Auto merge of #67096 - mark-i-m:fix-rustc-guide-2, r=ehuss

Update rustc-guide
diff --git a/Cargo.lock b/Cargo.lock
index 26727c5..113b7e7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2055,12 +2055,13 @@
 
 [[package]]
 name = "measureme"
-version = "0.4.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cd21b0e6e1af976b269ce062038fe5e1b9ca2f817ab7a3af09ec4210aebf0d30"
+checksum = "c420bbc064623934620b5ab2dc0cf96451b34163329e82f95e7fa1b7b99a6ac8"
 dependencies = [
  "byteorder",
  "memmap",
+ "parking_lot 0.9.0",
  "rustc-hash",
 ]
 
@@ -2072,9 +2073,9 @@
 
 [[package]]
 name = "memmap"
-version = "0.6.2"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2ffa2c986de11a9df78620c01eeaaf27d94d3ff02bf81bfcca953102dd0c6ff"
+checksum = "6585fd95e7bb50d6cc31e20d4cf9afb4e2ba16c5846fc76793f11218da9c475b"
 dependencies = [
  "libc",
  "winapi 0.3.8",
@@ -2213,6 +2214,7 @@
  "rand 0.7.0",
  "rustc-workspace-hack",
  "rustc_version",
+ "serde",
  "shell-escape",
  "vergen",
 ]
@@ -2575,9 +2577,9 @@
 
 [[package]]
 name = "polonius-engine"
-version = "0.10.0"
+version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "50fa9dbfd0d3d60594da338cfe6f94028433eecae4b11b7e83fd99759227bbfe"
+checksum = "1e478d7c38eb785c6416cbe58df12aa55d7aefa3759b6d3e044b2ed03f423cec"
 dependencies = [
  "datafrog",
  "log",
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 39d7ea9..7ea2bb1 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -810,6 +810,7 @@
                   !target.contains("emscripten") &&
                   !target.contains("wasm32") &&
                   !target.contains("nvptx") &&
+                  !target.contains("fortanix") &&
                   !target.contains("fuchsia") {
             Some(self.cc(target))
         } else {
diff --git a/src/ci/docker/README.md b/src/ci/docker/README.md
index a2d83ec..872f2c3 100644
--- a/src/ci/docker/README.md
+++ b/src/ci/docker/README.md
@@ -16,6 +16,13 @@
 
 Images will output artifacts in an `obj` dir at the root of a repository.
 
+**NOTE**: Re-using the same `obj` dir with different docker images with
+the same target triple (e.g. `dist-x86_64-linux` and `dist-various-1`)
+may result in strange linker errors, due shared library versions differing between platforms.
+
+If you encounter any issues when using multiple Docker images, try deleting your `obj` directory
+before running your command.
+
 ## Filesystem layout
 
 - Each directory, excluding `scripts` and `disabled`, corresponds to a docker image
diff --git a/src/libarena/lib.rs b/src/libarena/lib.rs
index 66d27a2..854942d 100644
--- a/src/libarena/lib.rs
+++ b/src/libarena/lib.rs
@@ -202,53 +202,18 @@
     #[inline]
     pub fn alloc_from_iter<I: IntoIterator<Item = T>>(&self, iter: I) -> &mut [T] {
         assert!(mem::size_of::<T>() != 0);
-        let mut iter = iter.into_iter();
-        let size_hint = iter.size_hint();
-
-        match size_hint {
-            (min, Some(max)) if min == max => {
-                // We know the exact number of elements the iterator will produce here
-                let len = min;
-
-                if len == 0 {
-                    return &mut [];
-                }
-
-                self.ensure_capacity(len);
-
-                let slice = self.ptr.get();
-
-                unsafe {
-                    let mut ptr = self.ptr.get();
-                    for _ in 0..len {
-                        // Write into uninitialized memory.
-                        ptr::write(ptr, iter.next().unwrap());
-                        // Advance the pointer.
-                        ptr = ptr.offset(1);
-                        // Update the pointer per iteration so if `iter.next()` panics
-                        // we destroy the correct amount
-                        self.ptr.set(ptr);
-                    }
-                    slice::from_raw_parts_mut(slice, len)
-                }
-            }
-            _ => {
-                cold_path(move || -> &mut [T] {
-                    let mut vec: SmallVec<[_; 8]> = iter.collect();
-                    if vec.is_empty() {
-                        return &mut [];
-                    }
-                    // Move the content to the arena by copying it and then forgetting
-                    // the content of the SmallVec
-                    unsafe {
-                        let len = vec.len();
-                        let start_ptr = self.alloc_raw_slice(len);
-                        vec.as_ptr().copy_to_nonoverlapping(start_ptr, len);
-                        vec.set_len(0);
-                        slice::from_raw_parts_mut(start_ptr, len)
-                    }
-                })
-            }
+        let mut vec: SmallVec<[_; 8]> = iter.into_iter().collect();
+        if vec.is_empty() {
+            return &mut [];
+        }
+        // Move the content to the arena by copying it and then forgetting
+        // the content of the SmallVec
+        unsafe {
+            let len = vec.len();
+            let start_ptr = self.alloc_raw_slice(len);
+            vec.as_ptr().copy_to_nonoverlapping(start_ptr, len);
+            vec.set_len(0);
+            slice::from_raw_parts_mut(start_ptr, len)
         }
     }
 
diff --git a/src/libcore/alloc.rs b/src/libcore/alloc.rs
index 4798769..20248f7 100644
--- a/src/libcore/alloc.rs
+++ b/src/libcore/alloc.rs
@@ -53,7 +53,7 @@
 
 impl Layout {
     /// Constructs a `Layout` from a given `size` and `align`,
-    /// or returns `LayoutErr` if either of the following conditions
+    /// or returns `LayoutErr` if any of the following conditions
     /// are not met:
     ///
     /// * `align` must not be zero,
@@ -137,7 +137,7 @@
     #[inline]
     pub fn for_value<T: ?Sized>(t: &T) -> Self {
         let (size, align) = (mem::size_of_val(t), mem::align_of_val(t));
-        // See rationale in `new` for why this us using an unsafe variant below
+        // See rationale in `new` for why this is using an unsafe variant below
         debug_assert!(Layout::from_size_align(size, align).is_ok());
         unsafe {
             Layout::from_size_align_unchecked(size, align)
@@ -196,7 +196,7 @@
         //    valid.
         //
         // 2. `len + align - 1` can overflow by at most `align - 1`,
-        //    so the &-mask wth `!(align - 1)` will ensure that in the
+        //    so the &-mask with `!(align - 1)` will ensure that in the
         //    case of overflow, `len_rounded_up` will itself be 0.
         //    Thus the returned padding, when added to `len`, yields 0,
         //    which trivially satisfies the alignment `align`.
diff --git a/src/libcore/bool.rs b/src/libcore/bool.rs
index 617bdd2..1b3c254 100644
--- a/src/libcore/bool.rs
+++ b/src/libcore/bool.rs
@@ -9,12 +9,12 @@
     /// ```
     /// #![feature(bool_to_option)]
     ///
-    /// assert_eq!(false.then(0), None);
-    /// assert_eq!(true.then(0), Some(0));
+    /// assert_eq!(false.then_some(0), None);
+    /// assert_eq!(true.then_some(0), Some(0));
     /// ```
     #[unstable(feature = "bool_to_option", issue = "64260")]
     #[inline]
-    pub fn then<T>(self, t: T) -> Option<T> {
+    pub fn then_some<T>(self, t: T) -> Option<T> {
         if self {
             Some(t)
         } else {
@@ -29,12 +29,12 @@
     /// ```
     /// #![feature(bool_to_option)]
     ///
-    /// assert_eq!(false.then_with(|| 0), None);
-    /// assert_eq!(true.then_with(|| 0), Some(0));
+    /// assert_eq!(false.then(|| 0), None);
+    /// assert_eq!(true.then(|| 0), Some(0));
     /// ```
     #[unstable(feature = "bool_to_option", issue = "64260")]
     #[inline]
-    pub fn then_with<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
+    pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
         if self {
             Some(f())
         } else {
diff --git a/src/libcore/convert.rs b/src/libcore/convert/mod.rs
similarity index 98%
rename from src/libcore/convert.rs
rename to src/libcore/convert/mod.rs
index 08802b3..5414d9a 100644
--- a/src/libcore/convert.rs
+++ b/src/libcore/convert/mod.rs
@@ -40,6 +40,11 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+mod num;
+
+#[unstable(feature = "convert_float_to_int", issue = "67057")]
+pub use num::FloatToInt;
+
 /// The identity function.
 ///
 /// Two things are important to note about this function:
@@ -562,6 +567,7 @@
 ///
 /// [#64715]: https://github.com/rust-lang/rust/issues/64715
 #[stable(feature = "convert_infallible", since = "1.34.0")]
+#[allow(unused_attributes)] // FIXME(#58633): do a principled fix instead.
 #[rustc_reservation_impl = "permitting this impl would forbid us from adding \
                             `impl<T> From<!> for T` later; see rust-lang/rust#64715 for details"]
 impl<T> From<!> for T {
diff --git a/src/libcore/convert/num.rs b/src/libcore/convert/num.rs
new file mode 100644
index 0000000..0877dac
--- /dev/null
+++ b/src/libcore/convert/num.rs
@@ -0,0 +1,369 @@
+use super::{From, TryFrom};
+use crate::num::TryFromIntError;
+
+mod private {
+    /// This trait being unreachable from outside the crate
+    /// prevents other implementations of the `FloatToInt` trait,
+    /// which allows potentially adding more trait methods after the trait is `#[stable]`.
+    #[unstable(feature = "convert_float_to_int", issue = "67057")]
+    pub trait Sealed {}
+}
+
+/// Supporting trait for inherent methods of `f32` and `f64` such as `round_unchecked_to`.
+/// Typically doesn’t need to be used directly.
+#[unstable(feature = "convert_float_to_int", issue = "67057")]
+pub trait FloatToInt<Int>: private::Sealed + Sized {
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[doc(hidden)]
+    unsafe fn approx_unchecked(self) -> Int;
+}
+
+macro_rules! impl_float_to_int {
+    ( $Float: ident => $( $Int: ident )+ ) => {
+        #[unstable(feature = "convert_float_to_int", issue = "67057")]
+        impl private::Sealed for $Float {}
+        $(
+            #[unstable(feature = "convert_float_to_int", issue = "67057")]
+            impl FloatToInt<$Int> for $Float {
+                #[cfg(not(bootstrap))]
+                #[doc(hidden)]
+                #[inline]
+                unsafe fn approx_unchecked(self) -> $Int {
+                    crate::intrinsics::float_to_int_approx_unchecked(self)
+                }
+            }
+        )+
+    }
+}
+
+impl_float_to_int!(f32 => u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize);
+impl_float_to_int!(f64 => u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize);
+
+// Conversion traits for primitive integer and float types
+// Conversions T -> T are covered by a blanket impl and therefore excluded
+// Some conversions from and to usize/isize are not implemented due to portability concerns
+macro_rules! impl_from {
+    ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
+        #[$attr]
+        #[doc = $doc]
+        impl From<$Small> for $Large {
+            #[inline]
+            fn from(small: $Small) -> $Large {
+                small as $Large
+            }
+        }
+    };
+    ($Small: ty, $Large: ty, #[$attr:meta]) => {
+        impl_from!($Small,
+                   $Large,
+                   #[$attr],
+                   concat!("Converts `",
+                           stringify!($Small),
+                           "` to `",
+                           stringify!($Large),
+                           "` losslessly."));
+    }
+}
+
+macro_rules! impl_from_bool {
+    ($target: ty, #[$attr:meta]) => {
+        impl_from!(bool, $target, #[$attr], concat!("Converts a `bool` to a `",
+            stringify!($target), "`. The resulting value is `0` for `false` and `1` for `true`
+values.
+
+# Examples
+
+```
+assert_eq!(", stringify!($target), "::from(true), 1);
+assert_eq!(", stringify!($target), "::from(false), 0);
+```"));
+    };
+}
+
+// Bool -> Any
+impl_from_bool! { u8, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { u16, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { u32, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { u64, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { u128, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { usize, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { i8, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { i16, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { i32, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { i64, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { i128, #[stable(feature = "from_bool", since = "1.28.0")] }
+impl_from_bool! { isize, #[stable(feature = "from_bool", since = "1.28.0")] }
+
+// Unsigned -> Unsigned
+impl_from! { u8, u16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, u128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u8, usize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u16, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u16, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u16, u128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u32, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u32, u128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u64, u128, #[stable(feature = "i128", since = "1.26.0")] }
+
+// Signed -> Signed
+impl_from! { i8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i8, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { i8, isize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i16, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { i32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { i32, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { i64, i128, #[stable(feature = "i128", since = "1.26.0")] }
+
+// Unsigned -> Signed
+impl_from! { u8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u8, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u16, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
+impl_from! { u32, i128, #[stable(feature = "i128", since = "1.26.0")] }
+impl_from! { u64, i128, #[stable(feature = "i128", since = "1.26.0")] }
+
+// The C99 standard defines bounds on INTPTR_MIN, INTPTR_MAX, and UINTPTR_MAX
+// which imply that pointer-sized integers must be at least 16 bits:
+// https://port70.net/~nsz/c/c99/n1256.html#7.18.2.4
+impl_from! { u16, usize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
+impl_from! { u8, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
+impl_from! { i16, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
+
+// RISC-V defines the possibility of a 128-bit address space (RV128).
+
+// CHERI proposes 256-bit “capabilities”. Unclear if this would be relevant to usize/isize.
+// https://www.cl.cam.ac.uk/research/security/ctsrd/pdfs/20171017a-cheri-poster.pdf
+// http://www.csl.sri.com/users/neumann/2012resolve-cheri.pdf
+
+
+// Note: integers can only be represented with full precision in a float if
+// they fit in the significand, which is 24 bits in f32 and 53 bits in f64.
+// Lossy float conversions are not implemented at this time.
+
+// Signed -> Float
+impl_from! { i8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { i8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { i16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { i16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { i32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+
+// Unsigned -> Float
+impl_from! { u8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { u8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { u16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { u16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+
+// Float -> Float
+impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
+
+// no possible bounds violation
+macro_rules! try_from_unbounded {
+    ($source:ty, $($target:ty),*) => {$(
+        #[stable(feature = "try_from", since = "1.34.0")]
+        impl TryFrom<$source> for $target {
+            type Error = TryFromIntError;
+
+            /// Try to create the target number type from a source
+            /// number type. This returns an error if the source value
+            /// is outside of the range of the target type.
+            #[inline]
+            fn try_from(value: $source) -> Result<Self, Self::Error> {
+                Ok(value as $target)
+            }
+        }
+    )*}
+}
+
+// only negative bounds
+macro_rules! try_from_lower_bounded {
+    ($source:ty, $($target:ty),*) => {$(
+        #[stable(feature = "try_from", since = "1.34.0")]
+        impl TryFrom<$source> for $target {
+            type Error = TryFromIntError;
+
+            /// Try to create the target number type from a source
+            /// number type. This returns an error if the source value
+            /// is outside of the range of the target type.
+            #[inline]
+            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
+                if u >= 0 {
+                    Ok(u as $target)
+                } else {
+                    Err(TryFromIntError(()))
+                }
+            }
+        }
+    )*}
+}
+
+// unsigned to signed (only positive bound)
+macro_rules! try_from_upper_bounded {
+    ($source:ty, $($target:ty),*) => {$(
+        #[stable(feature = "try_from", since = "1.34.0")]
+        impl TryFrom<$source> for $target {
+            type Error = TryFromIntError;
+
+            /// Try to create the target number type from a source
+            /// number type. This returns an error if the source value
+            /// is outside of the range of the target type.
+            #[inline]
+            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
+                if u > (<$target>::max_value() as $source) {
+                    Err(TryFromIntError(()))
+                } else {
+                    Ok(u as $target)
+                }
+            }
+        }
+    )*}
+}
+
+// all other cases
+macro_rules! try_from_both_bounded {
+    ($source:ty, $($target:ty),*) => {$(
+        #[stable(feature = "try_from", since = "1.34.0")]
+        impl TryFrom<$source> for $target {
+            type Error = TryFromIntError;
+
+            /// Try to create the target number type from a source
+            /// number type. This returns an error if the source value
+            /// is outside of the range of the target type.
+            #[inline]
+            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
+                let min = <$target>::min_value() as $source;
+                let max = <$target>::max_value() as $source;
+                if u < min || u > max {
+                    Err(TryFromIntError(()))
+                } else {
+                    Ok(u as $target)
+                }
+            }
+        }
+    )*}
+}
+
+macro_rules! rev {
+    ($mac:ident, $source:ty, $($target:ty),*) => {$(
+        $mac!($target, $source);
+    )*}
+}
+
+// intra-sign conversions
+try_from_upper_bounded!(u16, u8);
+try_from_upper_bounded!(u32, u16, u8);
+try_from_upper_bounded!(u64, u32, u16, u8);
+try_from_upper_bounded!(u128, u64, u32, u16, u8);
+
+try_from_both_bounded!(i16, i8);
+try_from_both_bounded!(i32, i16, i8);
+try_from_both_bounded!(i64, i32, i16, i8);
+try_from_both_bounded!(i128, i64, i32, i16, i8);
+
+// unsigned-to-signed
+try_from_upper_bounded!(u8, i8);
+try_from_upper_bounded!(u16, i8, i16);
+try_from_upper_bounded!(u32, i8, i16, i32);
+try_from_upper_bounded!(u64, i8, i16, i32, i64);
+try_from_upper_bounded!(u128, i8, i16, i32, i64, i128);
+
+// signed-to-unsigned
+try_from_lower_bounded!(i8, u8, u16, u32, u64, u128);
+try_from_lower_bounded!(i16, u16, u32, u64, u128);
+try_from_lower_bounded!(i32, u32, u64, u128);
+try_from_lower_bounded!(i64, u64, u128);
+try_from_lower_bounded!(i128, u128);
+try_from_both_bounded!(i16, u8);
+try_from_both_bounded!(i32, u16, u8);
+try_from_both_bounded!(i64, u32, u16, u8);
+try_from_both_bounded!(i128, u64, u32, u16, u8);
+
+// usize/isize
+try_from_upper_bounded!(usize, isize);
+try_from_lower_bounded!(isize, usize);
+
+#[cfg(target_pointer_width = "16")]
+mod ptr_try_from_impls {
+    use super::TryFromIntError;
+    use crate::convert::TryFrom;
+
+    try_from_upper_bounded!(usize, u8);
+    try_from_unbounded!(usize, u16, u32, u64, u128);
+    try_from_upper_bounded!(usize, i8, i16);
+    try_from_unbounded!(usize, i32, i64, i128);
+
+    try_from_both_bounded!(isize, u8);
+    try_from_lower_bounded!(isize, u16, u32, u64, u128);
+    try_from_both_bounded!(isize, i8);
+    try_from_unbounded!(isize, i16, i32, i64, i128);
+
+    rev!(try_from_upper_bounded, usize, u32, u64, u128);
+    rev!(try_from_lower_bounded, usize, i8, i16);
+    rev!(try_from_both_bounded, usize, i32, i64, i128);
+
+    rev!(try_from_upper_bounded, isize, u16, u32, u64, u128);
+    rev!(try_from_both_bounded, isize, i32, i64, i128);
+}
+
+#[cfg(target_pointer_width = "32")]
+mod ptr_try_from_impls {
+    use super::TryFromIntError;
+    use crate::convert::TryFrom;
+
+    try_from_upper_bounded!(usize, u8, u16);
+    try_from_unbounded!(usize, u32, u64, u128);
+    try_from_upper_bounded!(usize, i8, i16, i32);
+    try_from_unbounded!(usize, i64, i128);
+
+    try_from_both_bounded!(isize, u8, u16);
+    try_from_lower_bounded!(isize, u32, u64, u128);
+    try_from_both_bounded!(isize, i8, i16);
+    try_from_unbounded!(isize, i32, i64, i128);
+
+    rev!(try_from_unbounded, usize, u32);
+    rev!(try_from_upper_bounded, usize, u64, u128);
+    rev!(try_from_lower_bounded, usize, i8, i16, i32);
+    rev!(try_from_both_bounded, usize, i64, i128);
+
+    rev!(try_from_unbounded, isize, u16);
+    rev!(try_from_upper_bounded, isize, u32, u64, u128);
+    rev!(try_from_unbounded, isize, i32);
+    rev!(try_from_both_bounded, isize, i64, i128);
+}
+
+#[cfg(target_pointer_width = "64")]
+mod ptr_try_from_impls {
+    use super::TryFromIntError;
+    use crate::convert::TryFrom;
+
+    try_from_upper_bounded!(usize, u8, u16, u32);
+    try_from_unbounded!(usize, u64, u128);
+    try_from_upper_bounded!(usize, i8, i16, i32, i64);
+    try_from_unbounded!(usize, i128);
+
+    try_from_both_bounded!(isize, u8, u16, u32);
+    try_from_lower_bounded!(isize, u64, u128);
+    try_from_both_bounded!(isize, i8, i16, i32);
+    try_from_unbounded!(isize, i64, i128);
+
+    rev!(try_from_unbounded, usize, u32, u64);
+    rev!(try_from_upper_bounded, usize, u128);
+    rev!(try_from_lower_bounded, usize, i8, i16, i32, i64);
+    rev!(try_from_both_bounded, usize, i128);
+
+    rev!(try_from_unbounded, isize, u16, u32);
+    rev!(try_from_upper_bounded, isize, u64, u128);
+    rev!(try_from_unbounded, isize, i32, i64);
+    rev!(try_from_both_bounded, isize, i128);
+}
diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 19928f3..18aae59 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -1144,6 +1144,11 @@
     /// May assume inputs are finite.
     pub fn frem_fast<T>(a: T, b: T) -> T;
 
+    /// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range
+    /// https://github.com/rust-lang/rust/issues/10184
+    #[cfg(not(bootstrap))]
+    pub fn float_to_int_approx_unchecked<Float, Int>(value: Float) -> Int;
+
 
     /// Returns the number of bits set in an integer type `T`
     pub fn ctpop<T>(x: T) -> T;
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 188ea1a..8a514f1 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -102,6 +102,7 @@
 #![feature(staged_api)]
 #![feature(std_internals)]
 #![feature(stmt_expr_attributes)]
+#![cfg_attr(not(bootstrap), feature(track_caller))]
 #![feature(transparent_unions)]
 #![feature(unboxed_closures)]
 #![feature(unsized_locals)]
diff --git a/src/libcore/num/f32.rs b/src/libcore/num/f32.rs
index 913c0f9..ac06f95 100644
--- a/src/libcore/num/f32.rs
+++ b/src/libcore/num/f32.rs
@@ -7,9 +7,10 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(not(bootstrap))]
+use crate::convert::FloatToInt;
 #[cfg(not(test))]
 use crate::intrinsics;
-
 use crate::mem;
 use crate::num::FpCategory;
 
@@ -400,6 +401,35 @@
         intrinsics::minnumf32(self, other)
     }
 
+    /// Rounds toward zero and converts to any primitive integer type,
+    /// assuming that the value is finite and fits in that type.
+    ///
+    /// ```
+    /// #![feature(float_approx_unchecked_to)]
+    ///
+    /// let value = 4.6_f32;
+    /// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
+    /// assert_eq!(rounded, 4);
+    ///
+    /// let value = -128.9_f32;
+    /// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
+    /// assert_eq!(rounded, std::i8::MIN);
+    /// ```
+    ///
+    /// # Safety
+    ///
+    /// The value must:
+    ///
+    /// * Not be `NaN`
+    /// * Not be infinite
+    /// * Be representable in the return type `Int`, after truncating off its fractional part
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[inline]
+    pub unsafe fn approx_unchecked_to<Int>(self) -> Int where Self: FloatToInt<Int> {
+        FloatToInt::<Int>::approx_unchecked(self)
+    }
+
     /// Raw transmutation to `u32`.
     ///
     /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
diff --git a/src/libcore/num/f64.rs b/src/libcore/num/f64.rs
index 6ca830b..794f77f 100644
--- a/src/libcore/num/f64.rs
+++ b/src/libcore/num/f64.rs
@@ -7,9 +7,10 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(not(bootstrap))]
+use crate::convert::FloatToInt;
 #[cfg(not(test))]
 use crate::intrinsics;
-
 use crate::mem;
 use crate::num::FpCategory;
 
@@ -413,6 +414,35 @@
         intrinsics::minnumf64(self, other)
     }
 
+    /// Rounds toward zero and converts to any primitive integer type,
+    /// assuming that the value is finite and fits in that type.
+    ///
+    /// ```
+    /// #![feature(float_approx_unchecked_to)]
+    ///
+    /// let value = 4.6_f32;
+    /// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
+    /// assert_eq!(rounded, 4);
+    ///
+    /// let value = -128.9_f32;
+    /// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
+    /// assert_eq!(rounded, std::i8::MIN);
+    /// ```
+    ///
+    /// # Safety
+    ///
+    /// The value must:
+    ///
+    /// * Not be `NaN`
+    /// * Not be infinite
+    /// * Be representable in the return type `Int`, after truncating off its fractional part
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[inline]
+    pub unsafe fn approx_unchecked_to<Int>(self) -> Int where Self: FloatToInt<Int> {
+        FloatToInt::<Int>::approx_unchecked(self)
+    }
+
     /// Raw transmutation to `u64`.
     ///
     /// This is currently identical to `transmute::<f64, u64>(self)` on all platforms.
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 4313248..585f144 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -4,7 +4,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use crate::convert::TryFrom;
 use crate::fmt;
 use crate::intrinsics;
 use crate::mem;
@@ -4701,7 +4700,7 @@
 /// The error type returned when a checked integral type conversion fails.
 #[stable(feature = "try_from", since = "1.34.0")]
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub struct TryFromIntError(());
+pub struct TryFromIntError(pub(crate) ());
 
 impl TryFromIntError {
     #[unstable(feature = "int_error_internals",
@@ -4728,206 +4727,6 @@
     }
 }
 
-// no possible bounds violation
-macro_rules! try_from_unbounded {
-    ($source:ty, $($target:ty),*) => {$(
-        #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
-            type Error = TryFromIntError;
-
-            /// Try to create the target number type from a source
-            /// number type. This returns an error if the source value
-            /// is outside of the range of the target type.
-            #[inline]
-            fn try_from(value: $source) -> Result<Self, Self::Error> {
-                Ok(value as $target)
-            }
-        }
-    )*}
-}
-
-// only negative bounds
-macro_rules! try_from_lower_bounded {
-    ($source:ty, $($target:ty),*) => {$(
-        #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
-            type Error = TryFromIntError;
-
-            /// Try to create the target number type from a source
-            /// number type. This returns an error if the source value
-            /// is outside of the range of the target type.
-            #[inline]
-            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
-                if u >= 0 {
-                    Ok(u as $target)
-                } else {
-                    Err(TryFromIntError(()))
-                }
-            }
-        }
-    )*}
-}
-
-// unsigned to signed (only positive bound)
-macro_rules! try_from_upper_bounded {
-    ($source:ty, $($target:ty),*) => {$(
-        #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
-            type Error = TryFromIntError;
-
-            /// Try to create the target number type from a source
-            /// number type. This returns an error if the source value
-            /// is outside of the range of the target type.
-            #[inline]
-            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
-                if u > (<$target>::max_value() as $source) {
-                    Err(TryFromIntError(()))
-                } else {
-                    Ok(u as $target)
-                }
-            }
-        }
-    )*}
-}
-
-// all other cases
-macro_rules! try_from_both_bounded {
-    ($source:ty, $($target:ty),*) => {$(
-        #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
-            type Error = TryFromIntError;
-
-            /// Try to create the target number type from a source
-            /// number type. This returns an error if the source value
-            /// is outside of the range of the target type.
-            #[inline]
-            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
-                let min = <$target>::min_value() as $source;
-                let max = <$target>::max_value() as $source;
-                if u < min || u > max {
-                    Err(TryFromIntError(()))
-                } else {
-                    Ok(u as $target)
-                }
-            }
-        }
-    )*}
-}
-
-macro_rules! rev {
-    ($mac:ident, $source:ty, $($target:ty),*) => {$(
-        $mac!($target, $source);
-    )*}
-}
-
-// intra-sign conversions
-try_from_upper_bounded!(u16, u8);
-try_from_upper_bounded!(u32, u16, u8);
-try_from_upper_bounded!(u64, u32, u16, u8);
-try_from_upper_bounded!(u128, u64, u32, u16, u8);
-
-try_from_both_bounded!(i16, i8);
-try_from_both_bounded!(i32, i16, i8);
-try_from_both_bounded!(i64, i32, i16, i8);
-try_from_both_bounded!(i128, i64, i32, i16, i8);
-
-// unsigned-to-signed
-try_from_upper_bounded!(u8, i8);
-try_from_upper_bounded!(u16, i8, i16);
-try_from_upper_bounded!(u32, i8, i16, i32);
-try_from_upper_bounded!(u64, i8, i16, i32, i64);
-try_from_upper_bounded!(u128, i8, i16, i32, i64, i128);
-
-// signed-to-unsigned
-try_from_lower_bounded!(i8, u8, u16, u32, u64, u128);
-try_from_lower_bounded!(i16, u16, u32, u64, u128);
-try_from_lower_bounded!(i32, u32, u64, u128);
-try_from_lower_bounded!(i64, u64, u128);
-try_from_lower_bounded!(i128, u128);
-try_from_both_bounded!(i16, u8);
-try_from_both_bounded!(i32, u16, u8);
-try_from_both_bounded!(i64, u32, u16, u8);
-try_from_both_bounded!(i128, u64, u32, u16, u8);
-
-// usize/isize
-try_from_upper_bounded!(usize, isize);
-try_from_lower_bounded!(isize, usize);
-
-#[cfg(target_pointer_width = "16")]
-mod ptr_try_from_impls {
-    use super::TryFromIntError;
-    use crate::convert::TryFrom;
-
-    try_from_upper_bounded!(usize, u8);
-    try_from_unbounded!(usize, u16, u32, u64, u128);
-    try_from_upper_bounded!(usize, i8, i16);
-    try_from_unbounded!(usize, i32, i64, i128);
-
-    try_from_both_bounded!(isize, u8);
-    try_from_lower_bounded!(isize, u16, u32, u64, u128);
-    try_from_both_bounded!(isize, i8);
-    try_from_unbounded!(isize, i16, i32, i64, i128);
-
-    rev!(try_from_upper_bounded, usize, u32, u64, u128);
-    rev!(try_from_lower_bounded, usize, i8, i16);
-    rev!(try_from_both_bounded, usize, i32, i64, i128);
-
-    rev!(try_from_upper_bounded, isize, u16, u32, u64, u128);
-    rev!(try_from_both_bounded, isize, i32, i64, i128);
-}
-
-#[cfg(target_pointer_width = "32")]
-mod ptr_try_from_impls {
-    use super::TryFromIntError;
-    use crate::convert::TryFrom;
-
-    try_from_upper_bounded!(usize, u8, u16);
-    try_from_unbounded!(usize, u32, u64, u128);
-    try_from_upper_bounded!(usize, i8, i16, i32);
-    try_from_unbounded!(usize, i64, i128);
-
-    try_from_both_bounded!(isize, u8, u16);
-    try_from_lower_bounded!(isize, u32, u64, u128);
-    try_from_both_bounded!(isize, i8, i16);
-    try_from_unbounded!(isize, i32, i64, i128);
-
-    rev!(try_from_unbounded, usize, u32);
-    rev!(try_from_upper_bounded, usize, u64, u128);
-    rev!(try_from_lower_bounded, usize, i8, i16, i32);
-    rev!(try_from_both_bounded, usize, i64, i128);
-
-    rev!(try_from_unbounded, isize, u16);
-    rev!(try_from_upper_bounded, isize, u32, u64, u128);
-    rev!(try_from_unbounded, isize, i32);
-    rev!(try_from_both_bounded, isize, i64, i128);
-}
-
-#[cfg(target_pointer_width = "64")]
-mod ptr_try_from_impls {
-    use super::TryFromIntError;
-    use crate::convert::TryFrom;
-
-    try_from_upper_bounded!(usize, u8, u16, u32);
-    try_from_unbounded!(usize, u64, u128);
-    try_from_upper_bounded!(usize, i8, i16, i32, i64);
-    try_from_unbounded!(usize, i128);
-
-    try_from_both_bounded!(isize, u8, u16, u32);
-    try_from_lower_bounded!(isize, u64, u128);
-    try_from_both_bounded!(isize, i8, i16, i32);
-    try_from_unbounded!(isize, i64, i128);
-
-    rev!(try_from_unbounded, usize, u32, u64);
-    rev!(try_from_upper_bounded, usize, u128);
-    rev!(try_from_lower_bounded, usize, i8, i16, i32, i64);
-    rev!(try_from_both_bounded, usize, i128);
-
-    rev!(try_from_unbounded, isize, u16, u32);
-    rev!(try_from_upper_bounded, isize, u64, u128);
-    rev!(try_from_unbounded, isize, i32, i64);
-    rev!(try_from_both_bounded, isize, i128);
-}
-
 #[doc(hidden)]
 trait FromStrRadixHelper: PartialOrd + Copy {
     fn min_value() -> Self;
@@ -5110,131 +4909,3 @@
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use crate::num::dec2flt::ParseFloatError;
-
-// Conversion traits for primitive integer and float types
-// Conversions T -> T are covered by a blanket impl and therefore excluded
-// Some conversions from and to usize/isize are not implemented due to portability concerns
-macro_rules! impl_from {
-    ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
-        #[$attr]
-        #[doc = $doc]
-        impl From<$Small> for $Large {
-            #[inline]
-            fn from(small: $Small) -> $Large {
-                small as $Large
-            }
-        }
-    };
-    ($Small: ty, $Large: ty, #[$attr:meta]) => {
-        impl_from!($Small,
-                   $Large,
-                   #[$attr],
-                   concat!("Converts `",
-                           stringify!($Small),
-                           "` to `",
-                           stringify!($Large),
-                           "` losslessly."));
-    }
-}
-
-macro_rules! impl_from_bool {
-    ($target: ty, #[$attr:meta]) => {
-        impl_from!(bool, $target, #[$attr], concat!("Converts a `bool` to a `",
-            stringify!($target), "`. The resulting value is `0` for `false` and `1` for `true`
-values.
-
-# Examples
-
-```
-assert_eq!(", stringify!($target), "::from(true), 1);
-assert_eq!(", stringify!($target), "::from(false), 0);
-```"));
-    };
-}
-
-// Bool -> Any
-impl_from_bool! { u8, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { u16, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { u32, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { u64, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { u128, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { usize, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { i8, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { i16, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { i32, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { i64, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { i128, #[stable(feature = "from_bool", since = "1.28.0")] }
-impl_from_bool! { isize, #[stable(feature = "from_bool", since = "1.28.0")] }
-
-// Unsigned -> Unsigned
-impl_from! { u8, u16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, u128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u8, usize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u16, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u16, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u16, u128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u32, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u32, u128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u64, u128, #[stable(feature = "i128", since = "1.26.0")] }
-
-// Signed -> Signed
-impl_from! { i8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i8, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { i8, isize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i16, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { i32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { i32, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { i64, i128, #[stable(feature = "i128", since = "1.26.0")] }
-
-// Unsigned -> Signed
-impl_from! { u8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u8, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u16, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
-impl_from! { u32, i128, #[stable(feature = "i128", since = "1.26.0")] }
-impl_from! { u64, i128, #[stable(feature = "i128", since = "1.26.0")] }
-
-// The C99 standard defines bounds on INTPTR_MIN, INTPTR_MAX, and UINTPTR_MAX
-// which imply that pointer-sized integers must be at least 16 bits:
-// https://port70.net/~nsz/c/c99/n1256.html#7.18.2.4
-impl_from! { u16, usize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
-impl_from! { u8, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
-impl_from! { i16, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
-
-// RISC-V defines the possibility of a 128-bit address space (RV128).
-
-// CHERI proposes 256-bit “capabilities”. Unclear if this would be relevant to usize/isize.
-// https://www.cl.cam.ac.uk/research/security/ctsrd/pdfs/20171017a-cheri-poster.pdf
-// http://www.csl.sri.com/users/neumann/2012resolve-cheri.pdf
-
-
-// Note: integers can only be represented with full precision in a float if
-// they fit in the significand, which is 24 bits in f32 and 53 bits in f64.
-// Lossy float conversions are not implemented at this time.
-
-// Signed -> Float
-impl_from! { i8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { i8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { i16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { i16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { i32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-
-// Unsigned -> Float
-impl_from! { u8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { u8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { u16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { u16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
-
-// Float -> Float
-impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
diff --git a/src/libcore/panic.rs b/src/libcore/panic.rs
index 99b372d..e924ee2 100644
--- a/src/libcore/panic.rs
+++ b/src/libcore/panic.rs
@@ -177,6 +177,60 @@
 }
 
 impl<'a> Location<'a> {
+    /// Returns the source location of the caller of this function. If that function's caller is
+    /// annotated then its call location will be returned, and so on up the stack to the first call
+    /// within a non-tracked function body.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(track_caller)]
+    /// use core::panic::Location;
+    ///
+    /// /// Returns the [`Location`] at which it is called.
+    /// #[track_caller]
+    /// fn get_caller_location() -> &'static Location<'static> {
+    ///     Location::caller()
+    /// }
+    ///
+    /// /// Returns a [`Location`] from within this function's definition.
+    /// fn get_just_one_location() -> &'static Location<'static> {
+    ///     get_caller_location()
+    /// }
+    ///
+    /// let fixed_location = get_just_one_location();
+    /// assert_eq!(fixed_location.file(), file!());
+    /// assert_eq!(fixed_location.line(), 15);
+    /// assert_eq!(fixed_location.column(), 5);
+    ///
+    /// // running the same untracked function in a different location gives us the same result
+    /// let second_fixed_location = get_just_one_location();
+    /// assert_eq!(fixed_location.file(), second_fixed_location.file());
+    /// assert_eq!(fixed_location.line(), second_fixed_location.line());
+    /// assert_eq!(fixed_location.column(), second_fixed_location.column());
+    ///
+    /// let this_location = get_caller_location();
+    /// assert_eq!(this_location.file(), file!());
+    /// assert_eq!(this_location.line(), 29);
+    /// assert_eq!(this_location.column(), 21);
+    ///
+    /// // running the tracked function in a different location produces a different value
+    /// let another_location = get_caller_location();
+    /// assert_eq!(this_location.file(), another_location.file());
+    /// assert_ne!(this_location.line(), another_location.line());
+    /// assert_ne!(this_location.column(), another_location.column());
+    /// ```
+    #[cfg(not(bootstrap))]
+    #[unstable(feature = "track_caller",
+               reason = "uses #[track_caller] which is not yet stable",
+               issue = "47809")]
+    #[track_caller]
+    pub const fn caller() -> &'static Location<'static> {
+        crate::intrinsics::caller_location()
+    }
+}
+
+impl<'a> Location<'a> {
     #![unstable(feature = "panic_internals",
                 reason = "internal details of the implementation of the `panic!` \
                           and related macros",
diff --git a/src/libcore/tests/bool.rs b/src/libcore/tests/bool.rs
index 0f1e6e8..e89eb2c 100644
--- a/src/libcore/tests/bool.rs
+++ b/src/libcore/tests/bool.rs
@@ -1,7 +1,7 @@
 #[test]
 fn test_bool_to_option() {
-    assert_eq!(false.then(0), None);
-    assert_eq!(true.then(0), Some(0));
-    assert_eq!(false.then_with(|| 0), None);
-    assert_eq!(true.then_with(|| 0), Some(0));
+    assert_eq!(false.then_some(0), None);
+    assert_eq!(true.then_some(0), Some(0));
+    assert_eq!(false.then(|| 0), None);
+    assert_eq!(true.then(|| 0), Some(0));
 }
diff --git a/src/libfmt_macros/lib.rs b/src/libfmt_macros/lib.rs
index 900c6ed..2ecbe77 100644
--- a/src/libfmt_macros/lib.rs
+++ b/src/libfmt_macros/lib.rs
@@ -11,6 +11,7 @@
 #![feature(nll)]
 #![feature(rustc_private)]
 #![feature(unicode_internals)]
+#![feature(bool_to_option)]
 
 pub use Piece::*;
 pub use Position::*;
@@ -644,11 +645,7 @@
                 break;
             }
         }
-        if found {
-            Some(cur)
-        } else {
-            None
-        }
+        found.then_some(cur)
     }
 }
 
diff --git a/src/librustc/Cargo.toml b/src/librustc/Cargo.toml
index f8ad6f8..a4536bb 100644
--- a/src/librustc/Cargo.toml
+++ b/src/librustc/Cargo.toml
@@ -20,7 +20,7 @@
 log = { version = "0.4", features = ["release_max_level_info", "std"] }
 rustc-rayon = "0.3.0"
 rustc-rayon-core = "0.3.0"
-polonius-engine  = "0.10.0"
+polonius-engine = "0.11.0"
 rustc_apfloat = { path = "../librustc_apfloat" }
 rustc_feature = { path = "../librustc_feature" }
 rustc_target = { path = "../librustc_target" }
@@ -37,6 +37,6 @@
 chalk-engine = { version = "0.9.0", default-features=false }
 rustc_fs_util = { path = "../librustc_fs_util" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
-measureme = "0.4"
+measureme = "0.5"
 rustc_error_codes = { path = "../librustc_error_codes" }
 rustc_session = { path = "../librustc_session" }
diff --git a/src/librustc/arena.rs b/src/librustc/arena.rs
index 364a35f..eb7a170 100644
--- a/src/librustc/arena.rs
+++ b/src/librustc/arena.rs
@@ -23,17 +23,17 @@
             [] generics: rustc::ty::Generics,
             [] trait_def: rustc::ty::TraitDef,
             [] adt_def: rustc::ty::AdtDef,
-            [] steal_mir: rustc::ty::steal::Steal<rustc::mir::BodyCache<$tcx>>,
-            [] mir: rustc::mir::BodyCache<$tcx>,
+            [] steal_mir: rustc::ty::steal::Steal<rustc::mir::BodyAndCache<$tcx>>,
+            [] mir: rustc::mir::BodyAndCache<$tcx>,
             [] steal_promoted: rustc::ty::steal::Steal<
                 rustc_index::vec::IndexVec<
                     rustc::mir::Promoted,
-                    rustc::mir::BodyCache<$tcx>
+                    rustc::mir::BodyAndCache<$tcx>
                 >
             >,
             [] promoted: rustc_index::vec::IndexVec<
                 rustc::mir::Promoted,
-                rustc::mir::BodyCache<$tcx>
+                rustc::mir::BodyAndCache<$tcx>
             >,
             [] tables: rustc::ty::TypeckTables<$tcx>,
             [] const_allocs: rustc::mir::interpret::Allocation,
diff --git a/src/librustc/dep_graph/graph.rs b/src/librustc/dep_graph/graph.rs
index 0104507..d952bf7 100644
--- a/src/librustc/dep_graph/graph.rs
+++ b/src/librustc/dep_graph/graph.rs
@@ -710,14 +710,25 @@
                                 return None
                             }
                             None => {
-                                if !tcx.sess.has_errors() {
+                                if !tcx.sess.has_errors_or_delayed_span_bugs() {
                                     bug!("try_mark_previous_green() - Forcing the DepNode \
                                           should have set its color")
                                 } else {
-                                    // If the query we just forced has resulted
-                                    // in some kind of compilation error, we
-                                    // don't expect that the corresponding
-                                    // dep-node color has been updated.
+                                    // If the query we just forced has resulted in
+                                    // some kind of compilation error, we cannot rely on
+                                    // the dep-node color having been properly updated.
+                                    // This means that the query system has reached an
+                                    // invalid state. We let the compiler continue (by
+                                    // returning `None`) so it can emit error messages
+                                    // and wind down, but rely on the fact that this
+                                    // invalid state will not be persisted to the
+                                    // incremental compilation cache because of
+                                    // compilation errors being present.
+                                    debug!("try_mark_previous_green({:?}) - END - \
+                                            dependency {:?} resulted in compilation error",
+                                           dep_node,
+                                           dep_dep_node);
+                                    return None
                                 }
                             }
                         }
diff --git a/src/librustc/hir/map/blocks.rs b/src/librustc/hir/map/blocks.rs
index f25f3b5..8f9f398 100644
--- a/src/librustc/hir/map/blocks.rs
+++ b/src/librustc/hir/map/blocks.rs
@@ -147,13 +147,7 @@
             map::Node::Expr(e) => e.is_fn_like(),
             _ => false
         };
-        if fn_like {
-            Some(FnLikeNode {
-                node,
-            })
-        } else {
-            None
-        }
+        fn_like.then_some(FnLikeNode { node })
     }
 
     pub fn body(self) -> ast::BodyId {
diff --git a/src/librustc/infer/outlives/verify.rs b/src/librustc/infer/outlives/verify.rs
index 3110b02..3e28145 100644
--- a/src/librustc/infer/outlives/verify.rs
+++ b/src/librustc/infer/outlives/verify.rs
@@ -211,11 +211,7 @@
                 (r, p)
             );
             let p_ty = p.to_ty(tcx);
-            if compare_ty(p_ty) {
-                Some(ty::OutlivesPredicate(p_ty, r))
-            } else {
-                None
-            }
+            compare_ty(p_ty).then_some(ty::OutlivesPredicate(p_ty, r))
         });
 
         param_bounds
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index e708c5a..24b87ff 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -29,6 +29,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
 #![feature(arbitrary_self_types)]
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(const_fn)]
diff --git a/src/librustc/lint/builtin.rs b/src/librustc/lint/builtin.rs
index 1aba73e..c4bc977 100644
--- a/src/librustc/lint/builtin.rs
+++ b/src/librustc/lint/builtin.rs
@@ -329,7 +329,7 @@
 
 declare_lint! {
     pub UNUSED_LABELS,
-    Allow,
+    Warn,
     "detects labels that are never used"
 }
 
diff --git a/src/librustc/mir/cache.rs b/src/librustc/mir/cache.rs
index 95e9f09..0704771 100644
--- a/src/librustc/mir/cache.rs
+++ b/src/librustc/mir/cache.rs
@@ -115,16 +115,16 @@
 }
 
 #[derive(Clone, Debug, HashStable, RustcEncodable, RustcDecodable, TypeFoldable)]
-pub struct BodyCache<'tcx> {
-    cache: Cache,
+pub struct BodyAndCache<'tcx> {
     body: Body<'tcx>,
+    cache: Cache,
 }
 
-impl BodyCache<'tcx> {
+impl BodyAndCache<'tcx> {
     pub fn new(body: Body<'tcx>) -> Self {
         Self {
-            cache: Cache::new(),
             body,
+            cache: Cache::new(),
         }
     }
 }
@@ -139,7 +139,7 @@
     };
 }
 
-impl BodyCache<'tcx> {
+impl BodyAndCache<'tcx> {
     pub fn ensure_predecessors(&mut self) {
         self.cache.ensure_predecessors(&self.body);
     }
@@ -148,8 +148,8 @@
         self.cache.predecessors(&self.body)
     }
 
-    pub fn unwrap_read_only(&self) -> ReadOnlyBodyCache<'_, 'tcx> {
-        ReadOnlyBodyCache::new(&self.cache, &self.body)
+    pub fn unwrap_read_only(&self) -> ReadOnlyBodyAndCache<'_, 'tcx> {
+        ReadOnlyBodyAndCache::new(&self.body, &self.cache)
     }
 
     pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
@@ -163,7 +163,7 @@
     }
 }
 
-impl<'tcx> Index<BasicBlock> for BodyCache<'tcx> {
+impl<'tcx> Index<BasicBlock> for BodyAndCache<'tcx> {
     type Output = BasicBlockData<'tcx>;
 
     fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
@@ -171,13 +171,13 @@
     }
 }
 
-impl<'tcx> IndexMut<BasicBlock> for BodyCache<'tcx> {
+impl<'tcx> IndexMut<BasicBlock> for BodyAndCache<'tcx> {
     fn index_mut(&mut self, index: BasicBlock) -> &mut Self::Output {
         &mut self.basic_blocks_mut()[index]
     }
 }
 
-impl<'tcx> Deref for BodyCache<'tcx> {
+impl<'tcx> Deref for BodyAndCache<'tcx> {
     type Target = Body<'tcx>;
 
     fn deref(&self) -> &Self::Target {
@@ -185,26 +185,26 @@
     }
 }
 
-impl<'tcx> DerefMut for BodyCache<'tcx> {
+impl<'tcx> DerefMut for BodyAndCache<'tcx> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.body
     }
 }
 
 #[derive(Copy, Clone, Debug)]
-pub struct ReadOnlyBodyCache<'a, 'tcx> {
-    cache: &'a Cache,
+pub struct ReadOnlyBodyAndCache<'a, 'tcx> {
     body: &'a Body<'tcx>,
+    cache: &'a Cache,
 }
 
-impl ReadOnlyBodyCache<'a, 'tcx> {
-    fn new(cache: &'a Cache, body: &'a Body<'tcx>) -> Self {
+impl ReadOnlyBodyAndCache<'a, 'tcx> {
+    fn new(body: &'a Body<'tcx>, cache: &'a Cache) -> Self {
         assert!(
             cache.predecessors.is_some(),
-            "Cannot construct ReadOnlyBodyCache without computed predecessors");
+            "Cannot construct ReadOnlyBodyAndCache without computed predecessors");
         Self {
-            cache,
             body,
+            cache,
         }
     }
 
@@ -220,10 +220,6 @@
         self.cache.unwrap_predecessor_locations(loc, self.body)
     }
 
-    pub fn body(&self) -> &'a Body<'tcx> {
-        self.body
-    }
-
     pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
         &self.body.basic_blocks
     }
@@ -233,16 +229,16 @@
     }
 }
 
-impl graph::DirectedGraph for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::DirectedGraph for ReadOnlyBodyAndCache<'a, 'tcx> {
     type Node = BasicBlock;
 }
 
-impl graph::GraphPredecessors<'graph> for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::GraphPredecessors<'graph> for ReadOnlyBodyAndCache<'a, 'tcx> {
     type Item = BasicBlock;
     type Iter = IntoIter<BasicBlock>;
 }
 
-impl graph::WithPredecessors for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::WithPredecessors for ReadOnlyBodyAndCache<'a, 'tcx> {
     fn predecessors(
         &self,
         node: Self::Node,
@@ -251,19 +247,19 @@
     }
 }
 
-impl graph::WithNumNodes for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::WithNumNodes for ReadOnlyBodyAndCache<'a, 'tcx> {
     fn num_nodes(&self) -> usize {
         self.body.num_nodes()
     }
 }
 
-impl graph::WithStartNode for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::WithStartNode for ReadOnlyBodyAndCache<'a, 'tcx> {
     fn start_node(&self) -> Self::Node {
         self.body.start_node()
     }
 }
 
-impl graph::WithSuccessors for ReadOnlyBodyCache<'a, 'tcx> {
+impl graph::WithSuccessors for ReadOnlyBodyAndCache<'a, 'tcx> {
     fn successors(
         &self,
         node: Self::Node,
@@ -272,13 +268,13 @@
     }
 }
 
-impl<'a, 'b, 'tcx> graph::GraphSuccessors<'b> for ReadOnlyBodyCache<'a, 'tcx> {
+impl<'a, 'b, 'tcx> graph::GraphSuccessors<'b> for ReadOnlyBodyAndCache<'a, 'tcx> {
     type Item = BasicBlock;
     type Iter = iter::Cloned<Successors<'b>>;
 }
 
 
-impl Deref for ReadOnlyBodyCache<'a, 'tcx> {
+impl Deref for ReadOnlyBodyAndCache<'a, 'tcx> {
     type Target = &'a Body<'tcx>;
 
     fn deref(&self) -> &Self::Target {
diff --git a/src/librustc/mir/interpret/error.rs b/src/librustc/mir/interpret/error.rs
index 5573106..0dec7c0 100644
--- a/src/librustc/mir/interpret/error.rs
+++ b/src/librustc/mir/interpret/error.rs
@@ -370,6 +370,14 @@
     Unreachable,
     /// An enum discriminant was set to a value which was outside the range of valid values.
     InvalidDiscriminant(ScalarMaybeUndef),
+    /// A slice/array index projection went out-of-bounds.
+    BoundsCheckFailed { len: u64, index: u64 },
+    /// Something was divided by 0 (x / 0).
+    DivisionByZero,
+    /// Something was "remainded" by 0 (x % 0).
+    RemainderByZero,
+    /// Overflowing inbounds pointer arithmetic.
+    PointerArithOverflow,
 }
 
 impl fmt::Debug for UndefinedBehaviorInfo {
@@ -379,9 +387,18 @@
             Ub(msg) | UbExperimental(msg) =>
                 write!(f, "{}", msg),
             Unreachable =>
-                write!(f, "entered unreachable code"),
+                write!(f, "entering unreachable code"),
             InvalidDiscriminant(val) =>
-                write!(f, "encountered invalid enum discriminant {}", val),
+                write!(f, "encountering invalid enum discriminant {}", val),
+            BoundsCheckFailed { ref len, ref index } =>
+                write!(f, "indexing out of bounds: the len is {:?} but the index is {:?}",
+                    len, index),
+            DivisionByZero =>
+                write!(f, "dividing by zero"),
+            RemainderByZero =>
+                write!(f, "calculating the remainder with a divisor of zero"),
+            PointerArithOverflow =>
+                write!(f, "overflowing in-bounds pointer arithmetic"),
         }
     }
 }
diff --git a/src/librustc/mir/interpret/pointer.rs b/src/librustc/mir/interpret/pointer.rs
index 78320c7..0b27f51 100644
--- a/src/librustc/mir/interpret/pointer.rs
+++ b/src/librustc/mir/interpret/pointer.rs
@@ -1,6 +1,5 @@
 use super::{AllocId, InterpResult};
 
-use crate::mir;
 use crate::ty::layout::{self, HasDataLayout, Size};
 
 use rustc_macros::HashStable;
@@ -88,13 +87,13 @@
     #[inline]
     fn offset<'tcx>(&self, val: u64, i: u64) -> InterpResult<'tcx, u64> {
         let (res, over) = self.overflowing_offset(val, i);
-        if over { throw_panic!(Overflow(mir::BinOp::Add)) } else { Ok(res) }
+        if over { throw_ub!(PointerArithOverflow) } else { Ok(res) }
     }
 
     #[inline]
     fn signed_offset<'tcx>(&self, val: u64, i: i64) -> InterpResult<'tcx, u64> {
         let (res, over) = self.overflowing_signed_offset(val, i128::from(i));
-        if over { throw_panic!(Overflow(mir::BinOp::Add)) } else { Ok(res) }
+        if over { throw_ub!(PointerArithOverflow) } else { Ok(res) }
     }
 }
 
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index df5d499..a7f5a22 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -38,7 +38,7 @@
 use syntax_pos::{Span, DUMMY_SP};
 
 pub use crate::mir::interpret::AssertMessage;
-pub use crate::mir::cache::{BodyCache, ReadOnlyBodyCache};
+pub use crate::mir::cache::{BodyAndCache, ReadOnlyBodyAndCache};
 pub use crate::read_only;
 
 mod cache;
@@ -108,7 +108,7 @@
     pub yield_ty: Option<Ty<'tcx>>,
 
     /// Generator drop glue.
-    pub generator_drop: Option<Box<BodyCache<'tcx>>>,
+    pub generator_drop: Option<Box<BodyAndCache<'tcx>>>,
 
     /// The layout of a generator. Produced by the state transformation.
     pub generator_layout: Option<GeneratorLayout<'tcx>>,
@@ -242,11 +242,7 @@
     pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
         (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
-            if self.local_decls[local].is_user_variable() {
-                Some(local)
-            } else {
-                None
-            }
+            self.local_decls[local].is_user_variable().then_some(local)
         })
     }
 
@@ -2601,7 +2597,7 @@
     pub fn is_predecessor_of<'tcx>(
         &self,
         other: Location,
-        body: ReadOnlyBodyCache<'_, 'tcx>
+        body: ReadOnlyBodyAndCache<'_, 'tcx>
     ) -> bool {
         // If we are in the same block as the other location and are an earlier statement
         // then we are a predecessor of `other`.
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index 47a1d67..703e0cc 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -67,10 +67,10 @@
 
 macro_rules! body_cache_type {
     (mut $a:lifetime, $tcx:lifetime) => {
-        &mut BodyCache<$tcx>
+        &mut BodyAndCache<$tcx>
     };
     ($a:lifetime, $tcx:lifetime) => {
-        ReadOnlyBodyCache<$a, $tcx>
+        ReadOnlyBodyAndCache<$a, $tcx>
     };
 }
 
diff --git a/src/librustc/query/mod.rs b/src/librustc/query/mod.rs
index a6d7e5c..538b13c 100644
--- a/src/librustc/query/mod.rs
+++ b/src/librustc/query/mod.rs
@@ -106,30 +106,30 @@
 
         /// Fetch the MIR for a given `DefId` right after it's built - this includes
         /// unreachable code.
-        query mir_built(_: DefId) -> &'tcx Steal<mir::BodyCache<'tcx>> {}
+        query mir_built(_: DefId) -> &'tcx Steal<mir::BodyAndCache<'tcx>> {}
 
         /// Fetch the MIR for a given `DefId` up till the point where it is
         /// ready for const evaluation.
         ///
         /// See the README for the `mir` module for details.
-        query mir_const(_: DefId) -> &'tcx Steal<mir::BodyCache<'tcx>> {
+        query mir_const(_: DefId) -> &'tcx Steal<mir::BodyAndCache<'tcx>> {
             no_hash
         }
 
         query mir_validated(_: DefId) ->
             (
-                &'tcx Steal<mir::BodyCache<'tcx>>,
-                &'tcx Steal<IndexVec<mir::Promoted, mir::BodyCache<'tcx>>>
+                &'tcx Steal<mir::BodyAndCache<'tcx>>,
+                &'tcx Steal<IndexVec<mir::Promoted, mir::BodyAndCache<'tcx>>>
             ) {
             no_hash
         }
 
         /// MIR after our optimization passes have run. This is MIR that is ready
         /// for codegen. This is also the only query that can fetch non-local MIR, at present.
-        query optimized_mir(key: DefId) -> &'tcx mir::BodyCache<'tcx> {
+        query optimized_mir(key: DefId) -> &'tcx mir::BodyAndCache<'tcx> {
             cache_on_disk_if { key.is_local() }
             load_cached(tcx, id) {
-                let mir: Option<crate::mir::BodyCache<'tcx>>
+                let mir: Option<crate::mir::BodyAndCache<'tcx>>
                     = tcx.queries.on_disk_cache.try_load_query_result(tcx, id);
                 mir.map(|x| {
                     let cache = tcx.arena.alloc(x);
@@ -139,13 +139,13 @@
             }
         }
 
-        query promoted_mir(key: DefId) -> &'tcx IndexVec<mir::Promoted, mir::BodyCache<'tcx>> {
+        query promoted_mir(key: DefId) -> &'tcx IndexVec<mir::Promoted, mir::BodyAndCache<'tcx>> {
             cache_on_disk_if { key.is_local() }
             load_cached(tcx, id) {
                 let promoted: Option<
                     rustc_index::vec::IndexVec<
                         crate::mir::Promoted,
-                        crate::mir::BodyCache<'tcx>
+                        crate::mir::BodyAndCache<'tcx>
                     >> = tcx.queries.on_disk_cache.try_load_query_result(tcx, id);
                 promoted.map(|p| {
                     let cache = tcx.arena.alloc(p);
@@ -512,7 +512,7 @@
         /// in the case of closures, this will be redirected to the enclosing function.
         query region_scope_tree(_: DefId) -> &'tcx region::ScopeTree {}
 
-        query mir_shims(key: ty::InstanceDef<'tcx>) -> &'tcx mir::BodyCache<'tcx> {
+        query mir_shims(key: ty::InstanceDef<'tcx>) -> &'tcx mir::BodyAndCache<'tcx> {
             no_force
             desc { |tcx| "generating MIR shim for `{}`", tcx.def_path_str(key.def_id()) }
         }
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index ba44c6c..35017d6 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -363,11 +363,7 @@
             return None
         };
 
-        if tcx.has_attr(impl_def_id, sym::rustc_on_unimplemented) {
-            Some(impl_def_id)
-        } else {
-            None
-        }
+        tcx.has_attr(impl_def_id, sym::rustc_on_unimplemented).then_some(impl_def_id)
     }
 
     fn describe_generator(&self, body_id: hir::BodyId) -> Option<&'static str> {
@@ -2214,6 +2210,10 @@
         }
 
         let span = self.tcx.def_span(generator_did);
+        // Do not ICE on closure typeck (#66868).
+        if let None = self.tcx.hir().as_local_hir_id(generator_did) {
+            return false;
+        }
         let tables = self.tcx.typeck_tables_of(generator_did);
         debug!("note_obligation_cause_for_async_await: generator_did={:?} span={:?} ",
                generator_did, span);
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 6a0002c..f7e422b 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -8,6 +8,7 @@
 use crate::session::config::{BorrowckMode, OutputFilenames};
 use crate::session::config::CrateType;
 use crate::middle;
+use crate::middle::lang_items::PanicLocationLangItem;
 use crate::hir::{self, TraitCandidate, HirId, ItemKind, ItemLocalId, Node};
 use crate::hir::def::{Res, DefKind, Export};
 use crate::hir::def_id::{CrateNum, DefId, DefIndex, LOCAL_CRATE};
@@ -22,7 +23,7 @@
 use crate::middle::lang_items;
 use crate::middle::resolve_lifetime::{self, ObjectLifetimeDefault};
 use crate::middle::stability;
-use crate::mir::{BodyCache, Field, interpret, Local, Place, PlaceElem, ProjectionKind, Promoted};
+use crate::mir::{BodyAndCache, Field, interpret, Local, Place, PlaceElem, ProjectionKind, Promoted};
 use crate::mir::interpret::{ConstValue, Allocation, Scalar};
 use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef, Subst};
 use crate::ty::ReprOptions;
@@ -1083,17 +1084,17 @@
         &self.hir_map
     }
 
-    pub fn alloc_steal_mir(self, mir: BodyCache<'tcx>) -> &'tcx Steal<BodyCache<'tcx>> {
+    pub fn alloc_steal_mir(self, mir: BodyAndCache<'tcx>) -> &'tcx Steal<BodyAndCache<'tcx>> {
         self.arena.alloc(Steal::new(mir))
     }
 
-    pub fn alloc_steal_promoted(self, promoted: IndexVec<Promoted, BodyCache<'tcx>>) ->
-        &'tcx Steal<IndexVec<Promoted, BodyCache<'tcx>>> {
+    pub fn alloc_steal_promoted(self, promoted: IndexVec<Promoted, BodyAndCache<'tcx>>) ->
+        &'tcx Steal<IndexVec<Promoted, BodyAndCache<'tcx>>> {
         self.arena.alloc(Steal::new(promoted))
     }
 
-    pub fn intern_promoted(self, promoted: IndexVec<Promoted, BodyCache<'tcx>>) ->
-        &'tcx IndexVec<Promoted, BodyCache<'tcx>> {
+    pub fn intern_promoted(self, promoted: IndexVec<Promoted, BodyAndCache<'tcx>>) ->
+        &'tcx IndexVec<Promoted, BodyAndCache<'tcx>> {
         self.arena.alloc(promoted)
     }
 
@@ -1588,6 +1589,15 @@
     pub fn has_strict_asm_symbol_naming(&self) -> bool {
         self.sess.target.target.arch.contains("nvptx")
     }
+
+    /// Returns `&'static core::panic::Location<'static>`.
+    pub fn caller_location_ty(&self) -> Ty<'tcx> {
+        self.mk_imm_ref(
+            self.lifetimes.re_static,
+            self.type_of(self.require_lang_item(PanicLocationLangItem, None))
+                .subst(*self, self.mk_substs([self.lifetimes.re_static.into()].iter())),
+        )
+    }
 }
 
 impl<'tcx> GlobalCtxt<'tcx> {
diff --git a/src/librustc/ty/instance.rs b/src/librustc/ty/instance.rs
index 801dfa8..366951b 100644
--- a/src/librustc/ty/instance.rs
+++ b/src/librustc/ty/instance.rs
@@ -116,6 +116,10 @@
         }
         tcx.codegen_fn_attrs(self.def_id()).requests_inline()
     }
+
+    pub fn requires_caller_location(&self, tcx: TyCtxt<'_>) -> bool {
+        tcx.codegen_fn_attrs(self.def_id()).flags.contains(CodegenFnAttrFlags::TRACK_CALLER)
+    }
 }
 
 impl<'tcx> fmt::Display for Instance<'tcx> {
@@ -255,11 +259,8 @@
     ) -> Option<Instance<'tcx>> {
         debug!("resolve(def_id={:?}, substs={:?})", def_id, substs);
         Instance::resolve(tcx, param_env, def_id, substs).map(|mut resolved| {
-            let has_track_caller = |def| tcx.codegen_fn_attrs(def).flags
-                .contains(CodegenFnAttrFlags::TRACK_CALLER);
-
             match resolved.def {
-                InstanceDef::Item(def_id) if has_track_caller(def_id) => {
+                InstanceDef::Item(def_id) if resolved.def.requires_caller_location(tcx) => {
                     debug!(" => fn pointer created for function with #[track_caller]");
                     resolved.def = InstanceDef::ReifyShim(def_id);
                 }
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 7f93e8c..c7278dc 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -2434,6 +2434,7 @@
         cx: &C,
         sig: ty::PolyFnSig<'tcx>,
         extra_args: &[Ty<'tcx>],
+        caller_location: Option<Ty<'tcx>>,
         mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>,
     ) -> Self;
     fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
@@ -2448,13 +2449,19 @@
         + HasParamEnv<'tcx>,
 {
     fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
-        call::FnAbi::new_internal(cx, sig, extra_args, |ty, _| ArgAbi::new(cx.layout_of(ty)))
+        call::FnAbi::new_internal(cx, sig, extra_args, None, |ty, _| ArgAbi::new(cx.layout_of(ty)))
     }
 
     fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
         let sig = instance.fn_sig_for_fn_abi(cx.tcx());
 
-        call::FnAbi::new_internal(cx, sig, extra_args, |ty, arg_idx| {
+        let caller_location = if instance.def.requires_caller_location(cx.tcx()) {
+            Some(cx.tcx().caller_location_ty())
+        } else {
+            None
+        };
+
+        call::FnAbi::new_internal(cx, sig, extra_args, caller_location, |ty, arg_idx| {
             let mut layout = cx.layout_of(ty);
             // Don't pass the vtable, it's not an argument of the virtual fn.
             // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
@@ -2479,7 +2486,7 @@
                     'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
                         && !fat_pointer_layout.ty.is_region_ptr()
                     {
-                        'iter_fields: for i in 0..fat_pointer_layout.fields.count() {
+                        for i in 0..fat_pointer_layout.fields.count() {
                             let field_layout = fat_pointer_layout.field(cx, i);
 
                             if !field_layout.is_zst() {
@@ -2512,6 +2519,7 @@
         cx: &C,
         sig: ty::PolyFnSig<'tcx>,
         extra_args: &[Ty<'tcx>],
+        caller_location: Option<Ty<'tcx>>,
         mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>,
     ) -> Self {
         debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
@@ -2684,6 +2692,7 @@
                 .iter()
                 .cloned()
                 .chain(extra_args)
+                .chain(caller_location)
                 .enumerate()
                 .map(|(i, ty)| arg_of(ty, Some(i)))
                 .collect(),
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index c9a934e..78a31f4 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -18,7 +18,7 @@
 use crate::middle::cstore::CrateStoreDyn;
 use crate::middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
-use crate::mir::ReadOnlyBodyCache;
+use crate::mir::ReadOnlyBodyAndCache;
 use crate::mir::interpret::{GlobalId, ErrorHandled};
 use crate::mir::GeneratorLayout;
 use crate::session::CrateDisambiguator;
@@ -2784,11 +2784,7 @@
             }
         };
 
-        if is_associated_item {
-            Some(self.associated_item(def_id))
-        } else {
-            None
-        }
+        is_associated_item.then(|| self.associated_item(def_id))
     }
 
     fn associated_item_from_trait_item_ref(self,
@@ -2985,7 +2981,7 @@
     }
 
     /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
-    pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> ReadOnlyBodyCache<'tcx, 'tcx> {
+    pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> ReadOnlyBodyAndCache<'tcx, 'tcx> {
         match instance {
             ty::InstanceDef::Item(did) => {
                 self.optimized_mir(did).unwrap_read_only()
@@ -3253,7 +3249,7 @@
     let unnormalized_env = ty::ParamEnv::new(
         tcx.intern_predicates(&predicates),
         traits::Reveal::UserFacing,
-        if tcx.sess.opts.debugging_opts.chalk { Some(def_id) } else { None }
+        tcx.sess.opts.debugging_opts.chalk.then_some(def_id),
     );
 
     let body_id = tcx.hir().as_local_hir_id(def_id).map_or(hir::DUMMY_HIR_ID, |id| {
diff --git a/src/librustc/ty/query/job.rs b/src/librustc/ty/query/job.rs
index e5f4e79..2f30b79 100644
--- a/src/librustc/ty/query/job.rs
+++ b/src/librustc/ty/query/job.rs
@@ -303,13 +303,8 @@
         return true;
     }
 
-    visit_waiters(query, |_, successor| {
-        if connected_to_root(successor, visited) {
-            Some(None)
-        } else {
-            None
-        }
-    }).is_some()
+    visit_waiters(query, |_, successor| connected_to_root(successor, visited).then_some(None))
+        .is_some()
 }
 
 // Deterministically pick an query from a list
diff --git a/src/librustc_codegen_llvm/attributes.rs b/src/librustc_codegen_llvm/attributes.rs
index 33dc251..1ea9362 100644
--- a/src/librustc_codegen_llvm/attributes.rs
+++ b/src/librustc_codegen_llvm/attributes.rs
@@ -375,11 +375,7 @@
         let native_libs = tcx.native_libraries(cnum);
 
         let def_id_to_native_lib = native_libs.iter().filter_map(|lib|
-            if let Some(id) = lib.foreign_module {
-                Some((id, lib))
-            } else {
-                None
-            }
+            lib.foreign_module.map(|id| (id, lib))
         ).collect::<FxHashMap<_, _>>();
 
         let mut ret = FxHashMap::default();
diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index a05ba9c..ada29c3 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -22,7 +22,7 @@
 use rustc_data_structures::small_c_str::SmallCStr;
 use errors::{Handler, FatalError};
 
-use std::ffi::{CString, CStr};
+use std::ffi::CString;
 use std::fs;
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
@@ -833,8 +833,8 @@
             })
             .filter_map(|val| {
                 // Exclude some symbols that we know are not Rust symbols.
-                let name = CStr::from_ptr(llvm::LLVMGetValueName(val));
-                if ignored(name.to_bytes()) {
+                let name = llvm::get_value_name(val);
+                if ignored(name) {
                     None
                 } else {
                     Some((val, name))
@@ -842,7 +842,7 @@
             })
             .map(move |(val, name)| {
                 let mut imp_name = prefix.as_bytes().to_vec();
-                imp_name.extend(name.to_bytes());
+                imp_name.extend(name);
                 let imp_name = CString::new(imp_name).unwrap();
                 (imp_name, val)
             })
diff --git a/src/librustc_codegen_llvm/common.rs b/src/librustc_codegen_llvm/common.rs
index f38f9df..419e99d 100644
--- a/src/librustc_codegen_llvm/common.rs
+++ b/src/librustc_codegen_llvm/common.rs
@@ -245,11 +245,7 @@
             let (mut lo, mut hi) = (0u64, 0u64);
             let success = llvm::LLVMRustConstInt128Get(v, sign_ext,
                                                         &mut hi, &mut lo);
-            if success {
-                Some(hi_lo_to_u128(lo, hi))
-            } else {
-                None
-            }
+            success.then_some(hi_lo_to_u128(lo, hi))
         })
     }
 
diff --git a/src/librustc_codegen_llvm/consts.rs b/src/librustc_codegen_llvm/consts.rs
index 541b3d9..297aff9 100644
--- a/src/librustc_codegen_llvm/consts.rs
+++ b/src/librustc_codegen_llvm/consts.rs
@@ -21,7 +21,7 @@
 
 use rustc::hir::{self, CodegenFnAttrs, CodegenFnAttrFlags};
 
-use std::ffi::{CStr, CString};
+use std::ffi::CStr;
 
 pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll Value {
     let mut llvals = Vec::with_capacity(alloc.relocations().len() + 1);
@@ -392,16 +392,14 @@
             } else {
                 // If we created the global with the wrong type,
                 // correct the type.
-                let empty_string = const_cstr!("");
-                let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
-                let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
-                llvm::LLVMSetValueName(g, empty_string.as_ptr());
+                let name = llvm::get_value_name(g).to_vec();
+                llvm::set_value_name(g, b"");
 
                 let linkage = llvm::LLVMRustGetLinkage(g);
                 let visibility = llvm::LLVMRustGetVisibility(g);
 
                 let new_g = llvm::LLVMRustGetOrInsertGlobal(
-                    self.llmod, name_string.as_ptr(), val_llty);
+                    self.llmod, name.as_ptr().cast(), name.len(), val_llty);
 
                 llvm::LLVMRustSetLinkage(new_g, linkage);
                 llvm::LLVMRustSetVisibility(new_g, visibility);
diff --git a/src/librustc_codegen_llvm/debuginfo/mod.rs b/src/librustc_codegen_llvm/debuginfo/mod.rs
index c2359a2..a3782ec 100644
--- a/src/librustc_codegen_llvm/debuginfo/mod.rs
+++ b/src/librustc_codegen_llvm/debuginfo/mod.rs
@@ -32,7 +32,7 @@
 
 use libc::c_uint;
 use std::cell::RefCell;
-use std::ffi::{CStr, CString};
+use std::ffi::CString;
 
 use smallvec::SmallVec;
 use syntax_pos::{self, BytePos, Span, Pos};
@@ -255,23 +255,11 @@
             return;
         }
 
-        let old_name = unsafe {
-            CStr::from_ptr(llvm::LLVMGetValueName(value))
-        };
-        match old_name.to_str() {
-            Ok("") => {}
-            Ok(_) => {
-                // Avoid replacing the name if it already exists.
-                // While we could combine the names somehow, it'd
-                // get noisy quick, and the usefulness is dubious.
-                return;
-            }
-            Err(_) => return,
-        }
-
-        let cname = SmallCStr::new(name);
-        unsafe {
-            llvm::LLVMSetValueName(value, cname.as_ptr());
+        // Avoid replacing the name if it already exists.
+        // While we could combine the names somehow, it'd
+        // get noisy quick, and the usefulness is dubious.
+        if llvm::get_value_name(value).is_empty() {
+            llvm::set_value_name(value, name.as_bytes());
         }
     }
 }
diff --git a/src/librustc_codegen_llvm/declare.rs b/src/librustc_codegen_llvm/declare.rs
index 8b6fedc..fa9fc46 100644
--- a/src/librustc_codegen_llvm/declare.rs
+++ b/src/librustc_codegen_llvm/declare.rs
@@ -76,9 +76,8 @@
         name: &str, ty: &'ll Type
     ) -> &'ll Value {
         debug!("declare_global(name={:?})", name);
-        let namebuf = SmallCStr::new(name);
         unsafe {
-            llvm::LLVMRustGetOrInsertGlobal(self.llmod, namebuf.as_ptr(), ty)
+            llvm::LLVMRustGetOrInsertGlobal(self.llmod, name.as_ptr().cast(), name.len(), ty)
         }
     }
 
diff --git a/src/librustc_codegen_llvm/intrinsic.rs b/src/librustc_codegen_llvm/intrinsic.rs
index 9df75a8..1767ad1 100644
--- a/src/librustc_codegen_llvm/intrinsic.rs
+++ b/src/librustc_codegen_llvm/intrinsic.rs
@@ -516,9 +516,36 @@
                         return;
                     }
                 }
-
             },
 
+            "float_to_int_approx_unchecked" => {
+                if float_type_width(arg_tys[0]).is_none() {
+                    span_invalid_monomorphization_error(
+                        tcx.sess, span,
+                        &format!("invalid monomorphization of `float_to_int_approx_unchecked` \
+                                  intrinsic: expected basic float type, \
+                                  found `{}`", arg_tys[0]));
+                    return;
+                }
+                match int_type_width_signed(ret_ty, self.cx) {
+                    Some((width, signed)) => {
+                        if signed {
+                            self.fptosi(args[0].immediate(), self.cx.type_ix(width))
+                        } else {
+                            self.fptoui(args[0].immediate(), self.cx.type_ix(width))
+                        }
+                    }
+                    None => {
+                        span_invalid_monomorphization_error(
+                            tcx.sess, span,
+                            &format!("invalid monomorphization of `float_to_int_approx_unchecked` \
+                                      intrinsic:  expected basic integer type, \
+                                      found `{}`", ret_ty));
+                        return;
+                    }
+                }
+            }
+
             "discriminant_value" => {
                 args[0].deref(self.cx()).codegen_get_discr(self, ret_ty)
             }
diff --git a/src/librustc_codegen_llvm/lib.rs b/src/librustc_codegen_llvm/lib.rs
index 2ff5872..00a84f8 100644
--- a/src/librustc_codegen_llvm/lib.rs
+++ b/src/librustc_codegen_llvm/lib.rs
@@ -6,6 +6,7 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(const_cstr_unchecked)]
diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs
index 5362d18..5da3275 100644
--- a/src/librustc_codegen_llvm/llvm/ffi.rs
+++ b/src/librustc_codegen_llvm/llvm/ffi.rs
@@ -701,8 +701,8 @@
 
     // Operations on all values
     pub fn LLVMTypeOf(Val: &Value) -> &Type;
-    pub fn LLVMGetValueName(Val: &Value) -> *const c_char;
-    pub fn LLVMSetValueName(Val: &Value, Name: *const c_char);
+    pub fn LLVMGetValueName2(Val: &Value, Length: *mut size_t) -> *const c_char;
+    pub fn LLVMSetValueName2(Val: &Value, Name: *const c_char, NameLen: size_t);
     pub fn LLVMReplaceAllUsesWith(OldVal: &'a Value, NewVal: &'a Value);
     pub fn LLVMSetMetadata(Val: &'a Value, KindID: c_uint, Node: &'a Value);
 
@@ -774,7 +774,8 @@
     pub fn LLVMIsAGlobalVariable(GlobalVar: &Value) -> Option<&Value>;
     pub fn LLVMAddGlobal(M: &'a Module, Ty: &'a Type, Name: *const c_char) -> &'a Value;
     pub fn LLVMGetNamedGlobal(M: &Module, Name: *const c_char) -> Option<&Value>;
-    pub fn LLVMRustGetOrInsertGlobal(M: &'a Module, Name: *const c_char, T: &'a Type) -> &'a Value;
+    pub fn LLVMRustGetOrInsertGlobal(M: &'a Module, Name: *const c_char, NameLen: size_t,
+                                     T: &'a Type) -> &'a Value;
     pub fn LLVMRustInsertPrivateGlobal(M: &'a Module, T: &'a Type) -> &'a Value;
     pub fn LLVMGetFirstGlobal(M: &Module) -> Option<&Value>;
     pub fn LLVMGetNextGlobal(GlobalVar: &Value) -> Option<&Value>;
@@ -1811,7 +1812,7 @@
 
     pub fn LLVMRustPositionBuilderAtStart(B: &Builder<'a>, BB: &'a BasicBlock);
 
-    pub fn LLVMRustSetComdat(M: &'a Module, V: &'a Value, Name: *const c_char);
+    pub fn LLVMRustSetComdat(M: &'a Module, V: &'a Value, Name: *const c_char, NameLen: size_t);
     pub fn LLVMRustUnsetComdat(V: &Value);
     pub fn LLVMRustSetModulePICLevel(M: &Module);
     pub fn LLVMRustSetModulePIELevel(M: &Module);
diff --git a/src/librustc_codegen_llvm/llvm/mod.rs b/src/librustc_codegen_llvm/llvm/mod.rs
index 5781593..d2d4187 100644
--- a/src/librustc_codegen_llvm/llvm/mod.rs
+++ b/src/librustc_codegen_llvm/llvm/mod.rs
@@ -115,7 +115,8 @@
 // For more details on COMDAT sections see e.g., http://www.airs.com/blog/archives/52
 pub fn SetUniqueComdat(llmod: &Module, val: &'a Value) {
     unsafe {
-        LLVMRustSetComdat(llmod, val, LLVMGetValueName(val));
+        let name = get_value_name(val);
+        LLVMRustSetComdat(llmod, val, name.as_ptr().cast(), name.len());
     }
 }
 
@@ -217,6 +218,23 @@
     }
 }
 
+/// Safe wrapper for `LLVMGetValueName2` into a byte slice
+pub fn get_value_name(value: &'a Value) -> &'a [u8] {
+    unsafe {
+        let mut len = 0;
+        let data = LLVMGetValueName2(value, &mut len);
+        std::slice::from_raw_parts(data.cast(), len)
+    }
+}
+
+/// Safe wrapper for `LLVMSetValueName2` from a byte slice
+pub fn set_value_name(value: &Value, name: &[u8]) {
+    unsafe {
+        let data = name.as_ptr().cast();
+        LLVMSetValueName2(value, data, name.len());
+    }
+}
+
 pub fn build_string(f: impl FnOnce(&RustString)) -> Result<String, FromUtf8Error> {
     let sr = RustString {
         bytes: RefCell::new(Vec::new()),
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index 53d3c51..d489852 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -13,7 +13,7 @@
 bitflags = "1.2.1"
 cc = "1.0.1"
 num_cpus = "1.0"
-memmap = "0.6"
+memmap = "0.7"
 log = "0.4.5"
 libc = "0.2.44"
 jobserver = "0.1.11"
diff --git a/src/librustc_codegen_ssa/back/rpath.rs b/src/librustc_codegen_ssa/back/rpath.rs
index e27cb6d..cd3d999 100644
--- a/src/librustc_codegen_ssa/back/rpath.rs
+++ b/src/librustc_codegen_ssa/back/rpath.rs
@@ -119,11 +119,7 @@
     use std::path::Component;
 
     if path.is_absolute() != base.is_absolute() {
-        if path.is_absolute() {
-            Some(PathBuf::from(path))
-        } else {
-            None
-        }
+        path.is_absolute().then(|| PathBuf::from(path))
     } else {
         let mut ita = path.components();
         let mut itb = base.components();
diff --git a/src/librustc_codegen_ssa/back/symbol_export.rs b/src/librustc_codegen_ssa/back/symbol_export.rs
index f8b3e0f..cea5dc1 100644
--- a/src/librustc_codegen_ssa/back/symbol_export.rs
+++ b/src/librustc_codegen_ssa/back/symbol_export.rs
@@ -85,11 +85,7 @@
             match tcx.hir().get(hir_id) {
                 Node::ForeignItem(..) => {
                     let def_id = tcx.hir().local_def_id(hir_id);
-                    if tcx.is_statically_included_foreign_item(def_id) {
-                        Some(def_id)
-                    } else {
-                        None
-                    }
+                    tcx.is_statically_included_foreign_item(def_id).then_some(def_id)
                 }
 
                 // Only consider nodes that actually have exported symbols.
diff --git a/src/librustc_codegen_ssa/lib.rs b/src/librustc_codegen_ssa/lib.rs
index 9784d87..9919666 100644
--- a/src/librustc_codegen_ssa/lib.rs
+++ b/src/librustc_codegen_ssa/lib.rs
@@ -1,5 +1,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(core_intrinsics)]
@@ -68,22 +69,14 @@
                             emit_bc: bool,
                             emit_bc_compressed: bool,
                             outputs: &OutputFilenames) -> CompiledModule {
-        let object = if emit_obj {
-            Some(outputs.temp_path(OutputType::Object, Some(&self.name)))
-        } else {
-            None
-        };
-        let bytecode = if emit_bc {
-            Some(outputs.temp_path(OutputType::Bitcode, Some(&self.name)))
-        } else {
-            None
-        };
-        let bytecode_compressed = if emit_bc_compressed {
-            Some(outputs.temp_path(OutputType::Bitcode, Some(&self.name))
-                    .with_extension(RLIB_BYTECODE_EXTENSION))
-        } else {
-            None
-        };
+        let object = emit_obj
+            .then(|| outputs.temp_path(OutputType::Object, Some(&self.name)));
+        let bytecode = emit_bc
+            .then(|| outputs.temp_path(OutputType::Bitcode, Some(&self.name)));
+        let bytecode_compressed = emit_bc_compressed.then(|| {
+            outputs.temp_path(OutputType::Bitcode, Some(&self.name))
+                .with_extension(RLIB_BYTECODE_EXTENSION)
+        });
 
         CompiledModule {
             name: self.name.clone(),
diff --git a/src/librustc_codegen_ssa/mir/block.rs b/src/librustc_codegen_ssa/mir/block.rs
index 6dccf32..dabd097 100644
--- a/src/librustc_codegen_ssa/mir/block.rs
+++ b/src/librustc_codegen_ssa/mir/block.rs
@@ -153,7 +153,7 @@
     // a loop.
     fn maybe_sideeffect<Bx: BuilderMethods<'a, 'tcx>>(
         &self,
-        mir: mir::ReadOnlyBodyCache<'tcx, 'tcx>,
+        mir: mir::ReadOnlyBodyAndCache<'tcx, 'tcx>,
         bx: &mut Bx,
         targets: &[mir::BasicBlock],
     ) {
@@ -261,7 +261,11 @@
         if self.fn_abi.ret.layout.abi.is_uninhabited() {
             // Functions with uninhabited return values are marked `noreturn`,
             // so we should make sure that we never actually do.
+            // We play it safe by using a well-defined `abort`, but we could go for immediate UB
+            // if that turns out to be helpful.
             bx.abort();
+            // `abort` does not terminate the block, so we still need to generate
+            // an `unreachable` terminator after it.
             bx.unreachable();
             return;
         }
@@ -714,7 +718,7 @@
                     'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
                                     && !op.layout.ty.is_region_ptr()
                     {
-                        'iter_fields: for i in 0..op.layout.fields.count() {
+                        for i in 0..op.layout.fields.count() {
                             let field = op.extract_field(&mut bx, i);
                             if !field.layout.is_zst() {
                                 // we found the one non-zero-sized field that is allowed
@@ -770,6 +774,18 @@
                 &fn_abi.args[first_args.len()..])
         }
 
+        let needs_location =
+            instance.map_or(false, |i| i.def.requires_caller_location(self.cx.tcx()));
+        if needs_location {
+            assert_eq!(
+                fn_abi.args.len(), args.len() + 1,
+                "#[track_caller] fn's must have 1 more argument in their ABI than in their MIR",
+            );
+            let location = self.get_caller_location(&mut bx, span);
+            let last_arg = fn_abi.args.last().unwrap();
+            self.codegen_argument(&mut bx, location, &mut llargs, last_arg);
+        }
+
         let fn_ptr = match (llfn, instance) {
             (Some(llfn), _) => llfn,
             (None, Some(instance)) => bx.get_fn_addr(instance),
@@ -825,6 +841,8 @@
 
             mir::TerminatorKind::Abort => {
                 bx.abort();
+                // `abort` does not terminate the block, so we still need to generate
+                // an `unreachable` terminator after it.
                 bx.unreachable();
             }
 
@@ -1004,14 +1022,16 @@
         bx: &mut Bx,
         span: Span,
     ) -> OperandRef<'tcx, Bx::Value> {
-        let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
-        let caller = bx.tcx().sess.source_map().lookup_char_pos(topmost.lo());
-        let const_loc = bx.tcx().const_caller_location((
-            Symbol::intern(&caller.file.name.to_string()),
-            caller.line as u32,
-            caller.col_display as u32 + 1,
-        ));
-        OperandRef::from_const(bx, const_loc)
+        self.caller_location.unwrap_or_else(|| {
+            let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
+            let caller = bx.tcx().sess.source_map().lookup_char_pos(topmost.lo());
+            let const_loc = bx.tcx().const_caller_location((
+                Symbol::intern(&caller.file.name.to_string()),
+                caller.line as u32,
+                caller.col_display as u32 + 1,
+            ));
+            OperandRef::from_const(bx, const_loc)
+        })
     }
 
     fn get_personality_slot(
diff --git a/src/librustc_codegen_ssa/mir/mod.rs b/src/librustc_codegen_ssa/mir/mod.rs
index 3a157ca..e535aec 100644
--- a/src/librustc_codegen_ssa/mir/mod.rs
+++ b/src/librustc_codegen_ssa/mir/mod.rs
@@ -21,7 +21,7 @@
 pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     instance: Instance<'tcx>,
 
-    mir: mir::ReadOnlyBodyCache<'tcx, 'tcx>,
+    mir: mir::ReadOnlyBodyAndCache<'tcx, 'tcx>,
 
     debug_context: Option<FunctionDebugContext<Bx::DIScope>>,
 
@@ -77,6 +77,9 @@
     /// All `VarDebuginfo` from the MIR body, partitioned by `Local`.
     /// This is `None` if no variable debuginfo/names are needed.
     per_local_var_debug_info: Option<IndexVec<mir::Local, Vec<&'tcx mir::VarDebugInfo<'tcx>>>>,
+
+    /// Caller location propagated if this function has `#[track_caller]`.
+    caller_location: Option<OperandRef<'tcx, Bx::Value>>,
 }
 
 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
@@ -156,7 +159,7 @@
         }).collect();
 
     let (landing_pads, funclets) = create_funclets(&mir, &mut bx, &cleanup_kinds, &block_bxs);
-    let mir_body: &mir::Body<'_> = mir.body();
+    let mir_body: &mir::Body<'_> = *mir;
     let mut fx = FunctionCx {
         instance,
         mir,
@@ -172,13 +175,14 @@
         locals: IndexVec::new(),
         debug_context,
         per_local_var_debug_info: debuginfo::per_local_var_debug_info(cx.tcx(), mir_body),
+        caller_location: None,
     };
 
     let memory_locals = analyze::non_ssa_locals(&fx);
 
     // Allocate variable and temp allocas
     fx.locals = {
-        let args = arg_local_refs(&mut bx, &fx, &memory_locals);
+        let args = arg_local_refs(&mut bx, &mut fx, &memory_locals);
 
         let mut allocate_local = |local| {
             let decl = &mir_body.local_decls[local];
@@ -320,14 +324,14 @@
 /// indirect.
 fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx: &mut Bx,
-    fx: &FunctionCx<'a, 'tcx, Bx>,
+    fx: &mut FunctionCx<'a, 'tcx, Bx>,
     memory_locals: &BitSet<mir::Local>,
 ) -> Vec<LocalRef<'tcx, Bx::Value>> {
     let mir = fx.mir;
     let mut idx = 0;
     let mut llarg_idx = fx.fn_abi.ret.is_indirect() as usize;
 
-    mir.args_iter().enumerate().map(|(arg_index, local)| {
+    let args = mir.args_iter().enumerate().map(|(arg_index, local)| {
         let arg_decl = &mir.local_decls[local];
 
         if Some(local) == mir.spread_arg {
@@ -423,7 +427,27 @@
             bx.store_fn_arg(arg, &mut llarg_idx, tmp);
             LocalRef::Place(tmp)
         }
-    }).collect()
+    }).collect::<Vec<_>>();
+
+    if fx.instance.def.requires_caller_location(bx.tcx()) {
+        assert_eq!(
+            fx.fn_abi.args.len(), args.len() + 1,
+            "#[track_caller] fn's must have 1 more argument in their ABI than in their MIR",
+        );
+
+        let arg = fx.fn_abi.args.last().unwrap();
+        match arg.mode {
+            PassMode::Direct(_) => (),
+            _ => bug!("caller location must be PassMode::Direct, found {:?}", arg.mode),
+        }
+
+        fx.caller_location = Some(OperandRef {
+            val: OperandValue::Immediate(bx.get_param(llarg_idx)),
+            layout: arg.layout,
+        });
+    }
+
+    args
 }
 
 mod analyze;
diff --git a/src/librustc_codegen_ssa/mir/operand.rs b/src/librustc_codegen_ssa/mir/operand.rs
index 310b8ae..a6dec81 100644
--- a/src/librustc_codegen_ssa/mir/operand.rs
+++ b/src/librustc_codegen_ssa/mir/operand.rs
@@ -475,9 +475,10 @@
                             },
                         }
                         // Allow RalfJ to sleep soundly knowing that even refactorings that remove
-                        // the above error (or silence it under some conditions) will not cause UB
+                        // the above error (or silence it under some conditions) will not cause UB.
                         bx.abort();
-                        // We've errored, so we don't have to produce working code.
+                        // We still have to return an operand but it doesn't matter,
+                        // this code is unreachable.
                         let ty = self.monomorphize(&constant.literal.ty);
                         let layout = bx.cx().layout_of(ty);
                         bx.load_operand(PlaceRef::new_sized(
diff --git a/src/librustc_codegen_ssa/mir/place.rs b/src/librustc_codegen_ssa/mir/place.rs
index e250739..e60b886 100644
--- a/src/librustc_codegen_ssa/mir/place.rs
+++ b/src/librustc_codegen_ssa/mir/place.rs
@@ -333,6 +333,9 @@
         variant_index: VariantIdx
     ) {
         if self.layout.for_variant(bx.cx(), variant_index).abi.is_uninhabited() {
+            // We play it safe by using a well-defined `abort`, but we could go for immediate UB
+            // if that turns out to be helpful.
+            bx.abort();
             return;
         }
         match self.layout.variants {
@@ -488,10 +491,12 @@
                     },
                     Err(_) => {
                         // This is unreachable as long as runtime
-                        // and compile-time agree on values
+                        // and compile-time agree perfectly.
                         // With floats that won't always be true,
-                        // so we generate an abort.
+                        // so we generate a (safe) abort.
                         bx.abort();
+                        // We still have to return a place but it doesn't matter,
+                        // this code is unreachable.
                         let llval = bx.cx().const_undef(
                             bx.cx().type_ptr_to(bx.cx().backend_type(layout))
                         );
diff --git a/src/librustc_data_structures/Cargo.toml b/src/librustc_data_structures/Cargo.toml
index 0fd4711..7fa40b8 100644
--- a/src/librustc_data_structures/Cargo.toml
+++ b/src/librustc_data_structures/Cargo.toml
@@ -26,7 +26,7 @@
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_index = { path = "../librustc_index", package = "rustc_index" }
 bitflags = "1.2.1"
-measureme = "0.4"
+measureme = "0.5"
 
 [dependencies.parking_lot]
 version = "0.9"
diff --git a/src/librustc_data_structures/profiling.rs b/src/librustc_data_structures/profiling.rs
index 86f59bf..f9bfe5a 100644
--- a/src/librustc_data_structures/profiling.rs
+++ b/src/librustc_data_structures/profiling.rs
@@ -7,7 +7,7 @@
 use std::thread::ThreadId;
 use std::u32;
 
-use measureme::{StringId, TimestampKind};
+use measureme::{StringId};
 
 /// MmapSerializatioSink is faster on macOS and Linux
 /// but FileSerializationSink is faster on Windows
@@ -63,8 +63,8 @@
     ("incr-cache-load", EventFilter::INCR_CACHE_LOADS),
 ];
 
-fn thread_id_to_u64(tid: ThreadId) -> u64 {
-    unsafe { mem::transmute::<ThreadId, u64>(tid) }
+fn thread_id_to_u32(tid: ThreadId) -> u32 {
+    unsafe { mem::transmute::<ThreadId, u64>(tid) as u32 }
 }
 
 
@@ -149,11 +149,10 @@
     /// Record a query in-memory cache hit.
     #[inline(always)]
     pub fn query_cache_hit(&self, query_name: impl QueryName) {
-        self.non_guard_query_event(
+        self.instant_query_event(
             |profiler| profiler.query_cache_hit_event_kind,
             query_name,
             EventFilter::QUERY_CACHE_HITS,
-            TimestampKind::Instant,
         );
     }
 
@@ -184,22 +183,20 @@
     }
 
     #[inline(always)]
-    fn non_guard_query_event(
+    fn instant_query_event(
         &self,
         event_kind: fn(&SelfProfiler) -> StringId,
         query_name: impl QueryName,
         event_filter: EventFilter,
-        timestamp_kind: TimestampKind
     ) {
         drop(self.exec(event_filter, |profiler| {
             let event_id = SelfProfiler::get_query_name_string_id(query_name);
-            let thread_id = thread_id_to_u64(std::thread::current().id());
+            let thread_id = thread_id_to_u32(std::thread::current().id());
 
-            profiler.profiler.record_event(
+            profiler.profiler.record_instant_event(
                 event_kind(profiler),
                 event_id,
                 thread_id,
-                timestamp_kind,
             );
 
             TimingGuard::none()
@@ -306,7 +303,7 @@
         event_kind: StringId,
         event_id: StringId,
     ) -> TimingGuard<'a> {
-        let thread_id = thread_id_to_u64(std::thread::current().id());
+        let thread_id = thread_id_to_u32(std::thread::current().id());
         let raw_profiler = &profiler.profiler;
         let timing_guard = raw_profiler.start_recording_interval_event(event_kind,
                                                                        event_id,
diff --git a/src/librustc_data_structures/transitive_relation.rs b/src/librustc_data_structures/transitive_relation.rs
index a3926c1..bbf6999 100644
--- a/src/librustc_data_structures/transitive_relation.rs
+++ b/src/librustc_data_structures/transitive_relation.rs
@@ -373,6 +373,14 @@
         }
         matrix
     }
+
+    /// Lists all the base edges in the graph: the initial _non-transitive_ set of element
+    /// relations, which will be later used as the basis for the transitive closure computation.
+    pub fn base_edges(&self) -> impl Iterator<Item=(&T, &T)> {
+        self.edges
+            .iter()
+            .map(move |edge| (&self.elements[edge.source.0], &self.elements[edge.target.0]))
+    }
 }
 
 /// Pare down is used as a step in the LUB computation. It edits the
diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index 9e4b704..9c1bec3 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -18,7 +18,6 @@
 E0013: include_str!("./error_codes/E0013.md"),
 E0014: include_str!("./error_codes/E0014.md"),
 E0015: include_str!("./error_codes/E0015.md"),
-E0017: include_str!("./error_codes/E0017.md"),
 E0019: include_str!("./error_codes/E0019.md"),
 E0023: include_str!("./error_codes/E0023.md"),
 E0025: include_str!("./error_codes/E0025.md"),
diff --git a/src/librustc_error_codes/error_codes/E0017.md b/src/librustc_error_codes/error_codes/E0017.md
deleted file mode 100644
index d5e6857..0000000
--- a/src/librustc_error_codes/error_codes/E0017.md
+++ /dev/null
@@ -1,20 +0,0 @@
-References in statics and constants may only refer to immutable values.
-
-Erroneous code example:
-
-```compile_fail,E0017
-static X: i32 = 1;
-const C: i32 = 2;
-
-// these three are not allowed:
-const CR: &mut i32 = &mut C;
-static STATIC_REF: &'static mut i32 = &mut X;
-static CONST_REF: &'static mut i32 = &mut C;
-```
-
-Statics are shared everywhere, and if they refer to mutable data one might
-violate memory safety since holding multiple mutable references to shared data
-is not allowed.
-
-If you really want global mutable state, try using `static mut` or a global
-`UnsafeCell`.
diff --git a/src/librustc_feature/active.rs b/src/librustc_feature/active.rs
index fc880b9..363621b 100644
--- a/src/librustc_feature/active.rs
+++ b/src/librustc_feature/active.rs
@@ -523,6 +523,9 @@
     /// Allows the use of `#[cfg(sanitize = "option")]`; set when -Zsanitizer is used.
     (active, cfg_sanitize, "1.41.0", Some(39699), None),
 
+    /// Allows using `&mut` in constant functions.
+    (active, const_mut_refs, "1.41.0", Some(57349), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------
@@ -538,5 +541,4 @@
     sym::or_patterns,
     sym::let_chains,
     sym::raw_dylib,
-    sym::track_caller,
 ];
diff --git a/src/librustc_interface/lib.rs b/src/librustc_interface/lib.rs
index 76af434..9bb1878 100644
--- a/src/librustc_interface/lib.rs
+++ b/src/librustc_interface/lib.rs
@@ -1,3 +1,4 @@
+#![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(set_stdio)]
 #![feature(nll)]
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 2351843..2a4bc41 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -547,13 +547,7 @@
 }
 
 fn output_conflicts_with_dir(output_paths: &[PathBuf]) -> Option<PathBuf> {
-    let check = |output_path: &PathBuf| {
-        if output_path.is_dir() {
-            Some(output_path.clone())
-        } else {
-            None
-        }
-    };
+    let check = |output_path: &PathBuf| output_path.is_dir().then(|| output_path.clone());
     check_output(output_paths, check)
 }
 
diff --git a/src/librustc_interface/queries.rs b/src/librustc_interface/queries.rs
index 6103d42..e429b4d 100644
--- a/src/librustc_interface/queries.rs
+++ b/src/librustc_interface/queries.rs
@@ -22,7 +22,7 @@
 use syntax::{self, ast};
 
 /// Represent the result of a query.
-/// This result can be stolen with the `take` method and returned with the `give` method.
+/// This result can be stolen with the `take` method and generated with the `compute` method.
 pub struct Query<T> {
     result: RefCell<Option<Result<T>>>,
 }
@@ -37,7 +37,7 @@
     }
 
     /// Takes ownership of the query result. Further attempts to take or peek the query
-    /// result will panic unless it is returned by calling the `give` method.
+    /// result will panic unless it is generated by calling the `compute` method.
     pub fn take(&self) -> T {
         self.result
             .borrow_mut()
@@ -117,11 +117,9 @@
 
     pub fn dep_graph_future(&self) -> Result<&Query<Option<DepGraphFuture>>> {
         self.dep_graph_future.compute(|| {
-            Ok(if self.session().opts.build_dep_graph() {
-                Some(rustc_incremental::load_dep_graph(self.session()))
-            } else {
-                None
-            })
+            Ok(self.session().opts.build_dep_graph().then(|| {
+                rustc_incremental::load_dep_graph(self.session())
+            }))
         })
     }
 
diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index d8e20e1..8c225b8 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -107,11 +107,7 @@
 fn get_stack_size() -> Option<usize> {
     // FIXME: Hacks on hacks. If the env is trying to override the stack size
     // then *don't* set it explicitly.
-    if env::var_os("RUST_MIN_STACK").is_none() {
-        Some(STACK_SIZE)
-    } else {
-        None
-    }
+    env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
 }
 
 struct Sink(Arc<Mutex<Vec<u8>>>);
@@ -285,11 +281,7 @@
             } else {
                 "rustc"
             });
-            if candidate.exists() {
-                Some(candidate)
-            } else {
-                None
-            }
+            candidate.exists().then_some(candidate)
         })
         .next()
 }
diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index 0fd7145..10b00d3 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -1491,11 +1491,7 @@
             match pred {
                 ty::Predicate::TypeOutlives(outlives) => {
                     let outlives = outlives.skip_binder();
-                    if outlives.0.is_param(index) {
-                        Some(outlives.1)
-                    } else {
-                        None
-                    }
+                    outlives.0.is_param(index).then_some(outlives.1)
                 }
                 _ => None
             }
@@ -1554,11 +1550,7 @@
                             }),
                         _ => false,
                     };
-                    if is_inferred {
-                        Some((i, bound.span()))
-                    } else {
-                        None
-                    }
+                    is_inferred.then_some((i, bound.span()))
                 } else {
                     None
                 }
diff --git a/src/librustc_lint/lib.rs b/src/librustc_lint/lib.rs
index e60c025..b77f2cb 100644
--- a/src/librustc_lint/lib.rs
+++ b/src/librustc_lint/lib.rs
@@ -12,6 +12,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
 #![cfg_attr(test, feature(test))]
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(nll)]
@@ -340,7 +341,7 @@
         "converted into hard error, see https://github.com/rust-lang/rust/issues/46205");
     store.register_removed("legacy_constructor_visibility",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/39207");
-    store.register_removed("legacy_disrectory_ownership",
+    store.register_removed("legacy_directory_ownership",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/37872");
     store.register_removed("safe_extern_statics",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/36247");
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index b70cc52..88d1c50 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -12,7 +12,7 @@
 [dependencies]
 flate2 = "1.0"
 log = "0.4"
-memmap = "0.6"
+memmap = "0.7"
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index dbf2dcf..25bd2c4 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -802,11 +802,8 @@
         // First up we check for global allocators. Look at the crate graph here
         // and see what's a global allocator, including if we ourselves are a
         // global allocator.
-        let mut global_allocator = if self.cstore.has_global_allocator {
-            Some(Symbol::intern("this crate"))
-        } else {
-            None
-        };
+        let mut global_allocator = self.cstore.has_global_allocator
+            .then(|| Symbol::intern("this crate"));
         self.cstore.iter_crate_data(|_, data| {
             if !data.has_global_allocator() {
                 return
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index 8c0b734..aaaff7e 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -1,5 +1,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(core_intrinsics)]
 #![feature(crate_visibility_modifier)]
diff --git a/src/librustc_metadata/rmeta/decoder.rs b/src/librustc_metadata/rmeta/decoder.rs
index 6edd17f..0107a22 100644
--- a/src/librustc_metadata/rmeta/decoder.rs
+++ b/src/librustc_metadata/rmeta/decoder.rs
@@ -18,7 +18,7 @@
 use rustc_data_structures::svh::Svh;
 use rustc::dep_graph::{self, DepNodeIndex};
 use rustc::middle::lang_items;
-use rustc::mir::{self, BodyCache, interpret, Promoted};
+use rustc::mir::{self, BodyAndCache, interpret, Promoted};
 use rustc::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc::session::Session;
 use rustc::ty::{self, Ty, TyCtxt};
@@ -1079,7 +1079,7 @@
             self.root.per_def.mir.get(self, id).is_some()
     }
 
-    fn get_optimized_mir(&self, tcx: TyCtxt<'tcx>, id: DefIndex) -> BodyCache<'tcx> {
+    fn get_optimized_mir(&self, tcx: TyCtxt<'tcx>, id: DefIndex) -> BodyAndCache<'tcx> {
         let mut cache = self.root.per_def.mir.get(self, id)
             .filter(|_| !self.is_proc_macro(id))
             .unwrap_or_else(|| {
@@ -1094,7 +1094,7 @@
         &self,
         tcx: TyCtxt<'tcx>,
         id: DefIndex,
-    ) -> IndexVec<Promoted, BodyCache<'tcx>> {
+    ) -> IndexVec<Promoted, BodyAndCache<'tcx>> {
         let mut cache = self.root.per_def.promoted_mir.get(self, id)
             .filter(|_| !self.is_proc_macro(id))
             .unwrap_or_else(|| {
diff --git a/src/librustc_metadata/rmeta/mod.rs b/src/librustc_metadata/rmeta/mod.rs
index fdf43f0..5abae42 100644
--- a/src/librustc_metadata/rmeta/mod.rs
+++ b/src/librustc_metadata/rmeta/mod.rs
@@ -276,8 +276,8 @@
     // Also, as an optimization, a missing entry indicates an empty `&[]`.
     inferred_outlives: Table<DefIndex, Lazy!(&'tcx [(ty::Predicate<'tcx>, Span)])>,
     super_predicates: Table<DefIndex, Lazy!(ty::GenericPredicates<'tcx>)>,
-    mir: Table<DefIndex, Lazy!(mir::BodyCache<'tcx>)>,
-    promoted_mir: Table<DefIndex, Lazy!(IndexVec<mir::Promoted, mir::BodyCache<'tcx>>)>,
+    mir: Table<DefIndex, Lazy!(mir::BodyAndCache<'tcx>)>,
+    promoted_mir: Table<DefIndex, Lazy!(IndexVec<mir::Promoted, mir::BodyAndCache<'tcx>>)>,
 }
 
 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index 4afbb4d..7e3bd98 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -16,7 +16,7 @@
 itertools = "0.8"
 log = "0.4"
 log_settings = "0.1.1"
-polonius-engine  = "0.10.0"
+polonius-engine = "0.11.0"
 rustc = { path = "../librustc" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_mir/borrow_check/borrow_set.rs b/src/librustc_mir/borrow_check/borrow_set.rs
index 802464c..2980483 100644
--- a/src/librustc_mir/borrow_check/borrow_set.rs
+++ b/src/librustc_mir/borrow_check/borrow_set.rs
@@ -5,7 +5,7 @@
 use crate::dataflow::move_paths::MoveData;
 use rustc::mir::traversal;
 use rustc::mir::visit::{PlaceContext, Visitor, NonUseContext, MutatingUseContext};
-use rustc::mir::{self, Location, Body, Local, ReadOnlyBodyCache};
+use rustc::mir::{self, Location, Body, Local, ReadOnlyBodyAndCache};
 use rustc::ty::{RegionVid, TyCtxt};
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_index::vec::IndexVec;
@@ -90,7 +90,7 @@
 impl LocalsStateAtExit {
     fn build(
         locals_are_invalidated_at_exit: bool,
-        body: ReadOnlyBodyCache<'_, 'tcx>,
+        body: ReadOnlyBodyAndCache<'_, 'tcx>,
         move_data: &MoveData<'tcx>
     ) -> Self {
         struct HasStorageDead(BitSet<Local>);
@@ -124,7 +124,7 @@
 impl<'tcx> BorrowSet<'tcx> {
     pub fn build(
         tcx: TyCtxt<'tcx>,
-        body: ReadOnlyBodyCache<'_, 'tcx>,
+        body: ReadOnlyBodyAndCache<'_, 'tcx>,
         locals_are_invalidated_at_exit: bool,
         move_data: &MoveData<'tcx>,
     ) -> Self {
diff --git a/src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs b/src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs
index d14957b..a0f126f 100644
--- a/src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs
+++ b/src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs
@@ -240,15 +240,16 @@
                     let tcx = self.infcx.tcx;
                     let generics = tcx.generics_of(self.mir_def_id);
                     let param = generics.type_param(&param_ty, tcx);
-                    let generics = tcx.hir().get_generics(self.mir_def_id).unwrap();
-                    suggest_constraining_type_param(
-                        generics,
-                        &mut err,
-                        &param.name.as_str(),
-                        "Copy",
-                        tcx.sess.source_map(),
-                        span,
-                    );
+                    if let Some(generics) = tcx.hir().get_generics(self.mir_def_id) {
+                        suggest_constraining_type_param(
+                            generics,
+                            &mut err,
+                            &param.name.as_str(),
+                            "Copy",
+                            tcx.sess.source_map(),
+                            span,
+                        );
+                    }
                 }
                 let span = if let Some(local) = place.as_local() {
                     let decl = &self.body.local_decls[local];
diff --git a/src/librustc_mir/borrow_check/diagnostics/mutability_errors.rs b/src/librustc_mir/borrow_check/diagnostics/mutability_errors.rs
index 6449ae3..016a319 100644
--- a/src/librustc_mir/borrow_check/diagnostics/mutability_errors.rs
+++ b/src/librustc_mir/borrow_check/diagnostics/mutability_errors.rs
@@ -1,6 +1,6 @@
 use rustc::hir;
 use rustc::hir::Node;
-use rustc::mir::{self, ClearCrossCrate, Local, LocalInfo, Location, ReadOnlyBodyCache};
+use rustc::mir::{self, ClearCrossCrate, Local, LocalInfo, Location, ReadOnlyBodyAndCache};
 use rustc::mir::{Mutability, Place, PlaceRef, PlaceBase, ProjectionElem};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc_index::vec::Idx;
@@ -533,7 +533,7 @@
 // by trying (3.), then (2.) and finally falling back on (1.).
 fn suggest_ampmut<'tcx>(
     tcx: TyCtxt<'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     local: Local,
     local_decl: &mir::LocalDecl<'tcx>,
     opt_ty_info: Option<Span>,
diff --git a/src/librustc_mir/borrow_check/flows.rs b/src/librustc_mir/borrow_check/flows.rs
index ce5d2a1..57c544f 100644
--- a/src/librustc_mir/borrow_check/flows.rs
+++ b/src/librustc_mir/borrow_check/flows.rs
@@ -3,16 +3,15 @@
 //! FIXME: this might be better as a "generic" fixed-point combinator,
 //! but is not as ugly as it is right now.
 
-use rustc::mir::{BasicBlock, Local, Location};
-use rustc::ty::RegionVid;
+use rustc::mir::{BasicBlock, Location};
 use rustc_index::bit_set::BitIter;
 
 use crate::borrow_check::location::LocationIndex;
 
-use polonius_engine::Output;
+use crate::borrow_check::nll::PoloniusOutput;
 
 use crate::dataflow::indexes::BorrowIndex;
-use crate::dataflow::move_paths::{HasMoveData, MovePathIndex};
+use crate::dataflow::move_paths::HasMoveData;
 use crate::dataflow::Borrows;
 use crate::dataflow::EverInitializedPlaces;
 use crate::dataflow::MaybeUninitializedPlaces;
@@ -21,8 +20,6 @@
 use std::fmt;
 use std::rc::Rc;
 
-crate type PoloniusOutput = Output<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>;
-
 crate struct Flows<'b, 'tcx> {
     borrows: FlowAtLocation<'tcx, Borrows<'b, 'tcx>>,
     pub uninits: FlowAtLocation<'tcx, MaybeUninitializedPlaces<'b, 'tcx>>,
diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index a1932b5..427003f 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -9,8 +9,8 @@
 use rustc::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT};
 use rustc::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind};
 use rustc::mir::{
-    ClearCrossCrate, Local, Location, Body, BodyCache, Mutability, Operand, Place, PlaceBase,
-    PlaceElem, PlaceRef, ReadOnlyBodyCache, Static, StaticKind, read_only
+    ClearCrossCrate, Local, Location, Body, BodyAndCache, Mutability, Operand, Place, PlaceBase,
+    PlaceElem, PlaceRef, ReadOnlyBodyAndCache, Static, StaticKind, read_only
 };
 use rustc::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKind};
 use rustc::mir::{Terminator, TerminatorKind};
@@ -99,7 +99,7 @@
 fn do_mir_borrowck<'a, 'tcx>(
     infcx: &InferCtxt<'a, 'tcx>,
     input_body: &Body<'tcx>,
-    input_promoted: &IndexVec<Promoted, BodyCache<'tcx>>,
+    input_promoted: &IndexVec<Promoted, BodyAndCache<'tcx>>,
     def_id: DefId,
 ) -> BorrowCheckResult<'tcx> {
     debug!("do_mir_borrowck(def_id = {:?})", def_id);
@@ -161,7 +161,7 @@
     // will have a lifetime tied to the inference context.
     let body_clone: Body<'tcx> = input_body.clone();
     let mut promoted = input_promoted.clone();
-    let mut body = BodyCache::new(body_clone);
+    let mut body = BodyAndCache::new(body_clone);
     let free_regions =
         nll::replace_regions_in_mir(infcx, def_id, param_env, &mut body, &mut promoted);
     let body = read_only!(body); // no further changes
@@ -402,7 +402,7 @@
 
 crate struct MirBorrowckCtxt<'cx, 'tcx> {
     crate infcx: &'cx InferCtxt<'cx, 'tcx>,
-    body: ReadOnlyBodyCache<'cx, 'tcx>,
+    body: ReadOnlyBodyAndCache<'cx, 'tcx>,
     mir_def_id: DefId,
     param_env: ty::ParamEnv<'tcx>,
     move_data: &'cx MoveData<'tcx>,
@@ -493,7 +493,7 @@
     type FlowState = Flows<'cx, 'tcx>;
 
     fn body(&self) -> &'cx Body<'tcx> {
-        self.body.body()
+        *self.body
     }
 
     fn visit_block_entry(&mut self, bb: BasicBlock, flow_state: &Self::FlowState) {
diff --git a/src/librustc_mir/borrow_check/nll/facts.rs b/src/librustc_mir/borrow_check/nll/facts.rs
index 13e5769..a16c36d 100644
--- a/src/librustc_mir/borrow_check/nll/facts.rs
+++ b/src/librustc_mir/borrow_check/nll/facts.rs
@@ -1,6 +1,6 @@
 use crate::borrow_check::location::{LocationIndex, LocationTable};
 use crate::dataflow::indexes::{BorrowIndex, MovePathIndex};
-use polonius_engine::AllFacts as PoloniusAllFacts;
+use polonius_engine::AllFacts as PoloniusFacts;
 use polonius_engine::Atom;
 use rustc::mir::Local;
 use rustc::ty::{RegionVid, TyCtxt};
@@ -11,7 +11,18 @@
 use std::io::Write;
 use std::path::Path;
 
-crate type AllFacts = PoloniusAllFacts<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>;
+#[derive(Copy, Clone, Debug)]
+crate struct RustcFacts;
+
+impl polonius_engine::FactTypes for RustcFacts {
+    type Origin = RegionVid;
+    type Loan = BorrowIndex;
+    type Point = LocationIndex;
+    type Variable = Local;
+    type Path = MovePathIndex;
+}
+
+crate type AllFacts = PoloniusFacts<RustcFacts>;
 
 crate trait AllFactsExt {
     /// Returns `true` if there is a need to gather `AllFacts` given the
@@ -55,6 +66,7 @@
             wr.write_facts_to_path(self.[
                 borrow_region,
                 universal_region,
+                placeholder,
                 cfg_edge,
                 killed,
                 outlives,
@@ -69,6 +81,7 @@
                 initialized_at,
                 moved_out_at,
                 path_accessed_at,
+                known_subset,
             ])
         }
         Ok(())
diff --git a/src/librustc_mir/borrow_check/nll/invalidation.rs b/src/librustc_mir/borrow_check/nll/invalidation.rs
index 98679f2..2442bdf 100644
--- a/src/librustc_mir/borrow_check/nll/invalidation.rs
+++ b/src/librustc_mir/borrow_check/nll/invalidation.rs
@@ -11,7 +11,7 @@
 use crate::dataflow::indexes::BorrowIndex;
 use rustc::ty::{self, TyCtxt};
 use rustc::mir::visit::Visitor;
-use rustc::mir::{BasicBlock, Location, Body, Place, ReadOnlyBodyCache, Rvalue};
+use rustc::mir::{BasicBlock, Location, Body, Place, ReadOnlyBodyAndCache, Rvalue};
 use rustc::mir::{Statement, StatementKind};
 use rustc::mir::TerminatorKind;
 use rustc::mir::{Operand, BorrowKind};
@@ -22,7 +22,7 @@
     param_env: ty::ParamEnv<'tcx>,
     all_facts: &mut Option<AllFacts>,
     location_table: &LocationTable,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     borrow_set: &BorrowSet<'tcx>,
 ) {
     if all_facts.is_none() {
diff --git a/src/librustc_mir/borrow_check/nll/mod.rs b/src/librustc_mir/borrow_check/nll/mod.rs
index b936320..bbcb823 100644
--- a/src/librustc_mir/borrow_check/nll/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/mod.rs
@@ -1,10 +1,9 @@
 use crate::borrow_check::borrow_set::BorrowSet;
-use crate::borrow_check::location::{LocationIndex, LocationTable};
+use crate::borrow_check::location::LocationTable;
 use crate::borrow_check::nll::facts::AllFactsExt;
 use crate::borrow_check::nll::type_check::{MirTypeckResults, MirTypeckRegionConstraints};
 use crate::borrow_check::nll::region_infer::values::RegionValueElements;
-use crate::dataflow::indexes::BorrowIndex;
-use crate::dataflow::move_paths::{InitLocation, MoveData, MovePathIndex, InitKind};
+use crate::dataflow::move_paths::{InitLocation, MoveData, InitKind};
 use crate::dataflow::FlowAtLocation;
 use crate::dataflow::MaybeInitializedPlaces;
 use crate::transform::MirSource;
@@ -12,8 +11,8 @@
 use rustc::hir::def_id::DefId;
 use rustc::infer::InferCtxt;
 use rustc::mir::{ClosureOutlivesSubject, ClosureRegionRequirements,
-                 Local, Location, Body, BodyCache, LocalKind, BasicBlock,
-                 Promoted, ReadOnlyBodyCache};
+                 Local, Location, Body, BodyAndCache, LocalKind, BasicBlock,
+                 Promoted, ReadOnlyBodyAndCache};
 use rustc::ty::{self, RegionKind, RegionVid};
 use rustc_index::vec::IndexVec;
 use rustc_errors::Diagnostic;
@@ -43,10 +42,12 @@
 crate mod type_check;
 crate mod region_infer;
 
-use self::facts::AllFacts;
+use self::facts::{AllFacts, RustcFacts};
 use self::region_infer::RegionInferenceContext;
 use self::universal_regions::UniversalRegions;
 
+crate type PoloniusOutput = Output<RustcFacts>;
+
 /// Rewrites the regions in the MIR to use NLL variables, also
 /// scraping out the set of universal regions (e.g., region parameters)
 /// declared on the function. That set will need to be given to
@@ -55,8 +56,8 @@
     infcx: &InferCtxt<'cx, 'tcx>,
     def_id: DefId,
     param_env: ty::ParamEnv<'tcx>,
-    body: &mut BodyCache<'tcx>,
-    promoted: &mut IndexVec<Promoted, BodyCache<'tcx>>,
+    body: &mut BodyAndCache<'tcx>,
+    promoted: &mut IndexVec<Promoted, BodyAndCache<'tcx>>,
 ) -> UniversalRegions<'tcx> {
     debug!("replace_regions_in_mir(def_id={:?})", def_id);
 
@@ -158,8 +159,8 @@
     infcx: &InferCtxt<'cx, 'tcx>,
     def_id: DefId,
     universal_regions: UniversalRegions<'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
-    promoted: &IndexVec<Promoted, ReadOnlyBodyCache<'_, 'tcx>>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
+    promoted: &IndexVec<Promoted, ReadOnlyBodyAndCache<'_, 'tcx>>,
     local_names: &IndexVec<Local, Option<Symbol>>,
     upvars: &[Upvar],
     location_table: &LocationTable,
@@ -170,14 +171,10 @@
     errors_buffer: &mut Vec<Diagnostic>,
 ) -> (
     RegionInferenceContext<'tcx>,
-    Option<Rc<Output<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>>>,
+    Option<Rc<PoloniusOutput>>,
     Option<ClosureRegionRequirements<'tcx>>,
 ) {
-    let mut all_facts = if AllFacts::enabled(infcx.tcx) {
-        Some(AllFacts::default())
-    } else {
-        None
-    };
+    let mut all_facts = AllFacts::enabled(infcx.tcx).then_some(AllFacts::default());
 
     let universal_regions = Rc::new(universal_regions);
 
@@ -208,6 +205,39 @@
             .universal_region
             .extend(universal_regions.universal_regions());
         populate_polonius_move_facts(all_facts, move_data, location_table, &body);
+
+        // Emit universal regions facts, and their relations, for Polonius.
+        //
+        // 1: universal regions are modeled in Polonius as a pair:
+        // - the universal region vid itself.
+        // - a "placeholder loan" associated to this universal region. Since they don't exist in
+        //   the `borrow_set`, their `BorrowIndex` are synthesized as the universal region index
+        //   added to the existing number of loans, as if they succeeded them in the set.
+        //
+        let borrow_count = borrow_set.borrows.len();
+        debug!(
+            "compute_regions: polonius placeholders, num_universals={}, borrow_count={}",
+            universal_regions.len(),
+            borrow_count
+        );
+
+        for universal_region in universal_regions.universal_regions() {
+            let universal_region_idx = universal_region.index();
+            let placeholder_loan_idx = borrow_count + universal_region_idx;
+            all_facts.placeholder.push((universal_region, placeholder_loan_idx.into()));
+        }
+
+        // 2: the universal region relations `outlives` constraints are emitted as
+        //  `known_subset` facts.
+        for (fr1, fr2) in universal_region_relations.known_outlives() {
+            if fr1 != fr2 {
+                debug!(
+                    "compute_regions: emitting polonius `known_subset` fr1={:?}, fr2={:?}",
+                    fr1, fr2
+                );
+                all_facts.known_subset.push((*fr1, *fr2));
+            }
+        }
     }
 
     // Create the region inference context, taking ownership of the
@@ -269,7 +299,7 @@
 
         if infcx.tcx.sess.opts.debugging_opts.polonius {
             let algorithm = env::var("POLONIUS_ALGORITHM")
-                .unwrap_or_else(|_| String::from("Hybrid"));
+                .unwrap_or_else(|_| String::from("Naive"));
             let algorithm = Algorithm::from_str(&algorithm).unwrap();
             debug!("compute_regions: using polonius algorithm {:?}", algorithm);
             Some(Rc::new(Output::compute(
@@ -283,8 +313,15 @@
     });
 
     // Solve the region constraints.
-    let closure_region_requirements =
-        regioncx.solve(infcx, &body, local_names, upvars, def_id, errors_buffer);
+    let closure_region_requirements = regioncx.solve(
+        infcx,
+        &body,
+        local_names,
+        upvars,
+        def_id,
+        errors_buffer,
+        polonius_output.clone(),
+    );
 
     // Dump MIR results into a file, if that is enabled. This let us
     // write unit-tests, as well as helping with debugging.
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
index 85031d6..d62537b 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
@@ -44,7 +44,7 @@
 
 use self::values::{LivenessValues, RegionValueElements, RegionValues};
 use super::universal_regions::UniversalRegions;
-use super::ToRegionVid;
+use super::{PoloniusOutput, ToRegionVid};
 
 mod dump_mir;
 mod graphviz;
@@ -484,6 +484,7 @@
         upvars: &[Upvar],
         mir_def_id: DefId,
         errors_buffer: &mut Vec<Diagnostic>,
+        polonius_output: Option<Rc<PoloniusOutput>>,
     ) -> Option<ClosureRegionRequirements<'tcx>> {
         self.propagate_constraints(body);
 
@@ -493,7 +494,7 @@
         // functions below, which will trigger them to report errors
         // eagerly.
         let mut outlives_requirements =
-            if infcx.tcx.is_closure(mir_def_id) { Some(vec![]) } else { None };
+            infcx.tcx.is_closure(mir_def_id).then(|| vec![]);
 
         self.check_type_tests(
             infcx,
@@ -509,16 +510,33 @@
         // multiple problems.
         let mut region_naming = RegionErrorNamingCtx::new();
 
-        self.check_universal_regions(
-            infcx,
-            body,
-            local_names,
-            upvars,
-            mir_def_id,
-            outlives_requirements.as_mut(),
-            errors_buffer,
-            &mut region_naming,
-        );
+        // In Polonius mode, the errors about missing universal region relations are in the output
+        // and need to be emitted or propagated. Otherwise, we need to check whether the
+        // constraints were too strong, and if so, emit or propagate those errors.
+        if infcx.tcx.sess.opts.debugging_opts.polonius {
+            self.check_polonius_subset_errors(
+                infcx,
+                body,
+                local_names,
+                upvars,
+                mir_def_id,
+                outlives_requirements.as_mut(),
+                errors_buffer,
+                &mut region_naming,
+                polonius_output.expect("Polonius output is unavailable despite `-Z polonius`"),
+            );
+        } else {
+            self.check_universal_regions(
+                infcx,
+                body,
+                local_names,
+                upvars,
+                mir_def_id,
+                outlives_requirements.as_mut(),
+                errors_buffer,
+                &mut region_naming,
+            );
+        }
 
         self.check_member_constraints(infcx, mir_def_id, errors_buffer);
 
@@ -709,14 +727,11 @@
         let min = |r1: ty::RegionVid, r2: ty::RegionVid| -> Option<ty::RegionVid> {
             let r1_outlives_r2 = self.universal_region_relations.outlives(r1, r2);
             let r2_outlives_r1 = self.universal_region_relations.outlives(r2, r1);
-            if r1_outlives_r2 && r2_outlives_r1 {
-                Some(r1.min(r2))
-            } else if r1_outlives_r2 {
-                Some(r2)
-            } else if r2_outlives_r1 {
-                Some(r1)
-            } else {
-                None
+            match (r1_outlives_r2, r2_outlives_r1) {
+                (true, true) => Some(r1.min(r2)),
+                (true, false) => Some(r2),
+                (false, true) => Some(r1),
+                (false, false) => None,
             }
         };
         let mut min_choice = choice_regions[0];
@@ -1375,6 +1390,114 @@
         outlives_suggestion.add_suggestion(body, self, infcx, errors_buffer, region_naming);
     }
 
+    /// Checks if Polonius has found any unexpected free region relations.
+    ///
+    /// In Polonius terms, a "subset error" (or "illegal subset relation error") is the equivalent
+    /// of NLL's "checking if any region constraints were too strong": a placeholder origin `'a`
+    /// was unexpectedly found to be a subset of another placeholder origin `'b`, and means in NLL
+    /// terms that the "longer free region" `'a` outlived the "shorter free region" `'b`.
+    ///
+    /// More details can be found in this blog post by Niko:
+    /// http://smallcultfollowing.com/babysteps/blog/2019/01/17/polonius-and-region-errors/
+    ///
+    /// In the canonical example
+    ///
+    ///     fn foo<'a, 'b>(x: &'a u32) -> &'b u32 { x }
+    ///
+    /// returning `x` requires `&'a u32 <: &'b u32` and hence we establish (transitively) a
+    /// constraint that `'a: 'b`. It is an error that we have no evidence that this
+    /// constraint holds.
+    ///
+    /// If `propagated_outlives_requirements` is `Some`, then we will
+    /// push unsatisfied obligations into there. Otherwise, we'll
+    /// report them as errors.
+    fn check_polonius_subset_errors(
+        &self,
+        infcx: &InferCtxt<'_, 'tcx>,
+        body: &Body<'tcx>,
+        local_names: &IndexVec<Local, Option<Symbol>>,
+        upvars: &[Upvar],
+        mir_def_id: DefId,
+        mut propagated_outlives_requirements: Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
+        errors_buffer: &mut Vec<Diagnostic>,
+        region_naming: &mut RegionErrorNamingCtx,
+        polonius_output: Rc<PoloniusOutput>,
+    ) {
+        debug!(
+            "check_polonius_subset_errors: {} subset_errors",
+            polonius_output.subset_errors.len()
+        );
+
+        let mut outlives_suggestion = OutlivesSuggestionBuilder::new(mir_def_id, local_names);
+
+        // Similarly to `check_universal_regions`: a free region relation, which was not explicitly
+        // declared ("known") was found by Polonius, so emit an error, or propagate the
+        // requirements for our caller into the `propagated_outlives_requirements` vector.
+        //
+        // Polonius doesn't model regions ("origins") as CFG-subsets or durations, but the
+        // `longer_fr` and `shorter_fr` terminology will still be used here, for consistency with
+        // the rest of the NLL infrastructure. The "subset origin" is the "longer free region",
+        // and the "superset origin" is the outlived "shorter free region".
+        //
+        // Note: Polonius will produce a subset error at every point where the unexpected
+        // `longer_fr`'s "placeholder loan" is contained in the `shorter_fr`. This can be helpful
+        // for diagnostics in the future, e.g. to point more precisely at the key locations
+        // requiring this constraint to hold. However, the error and diagnostics code downstream
+        // expects that these errors are not duplicated (and that they are in a certain order).
+        // Otherwise, diagnostics messages such as the ones giving names like `'1` to elided or
+        // anonymous lifetimes for example, could give these names differently, while others like
+        // the outlives suggestions or the debug output from `#[rustc_regions]` would be
+        // duplicated. The polonius subset errors are deduplicated here, while keeping the
+        // CFG-location ordering.
+        let mut subset_errors: Vec<_> = polonius_output
+            .subset_errors
+            .iter()
+            .flat_map(|(_location, subset_errors)| subset_errors.iter())
+            .collect();
+        subset_errors.sort();
+        subset_errors.dedup();
+
+        for (longer_fr, shorter_fr) in subset_errors.into_iter() {
+            debug!("check_polonius_subset_errors: subset_error longer_fr={:?},\
+                shorter_fr={:?}", longer_fr, shorter_fr);
+
+            self.report_or_propagate_universal_region_error(
+                *longer_fr,
+                *shorter_fr,
+                infcx,
+                body,
+                local_names,
+                upvars,
+                mir_def_id,
+                &mut propagated_outlives_requirements,
+                &mut outlives_suggestion,
+                errors_buffer,
+                region_naming,
+            );
+        }
+
+        // Handle the placeholder errors as usual, until the chalk-rustc-polonius triumvirate has
+        // a more complete picture on how to separate this responsibility.
+        for (fr, fr_definition) in self.definitions.iter_enumerated() {
+            match fr_definition.origin {
+                NLLRegionVariableOrigin::FreeRegion => {
+                    // handled by polonius above
+                }
+
+                NLLRegionVariableOrigin::Placeholder(placeholder) => {
+                    self.check_bound_universal_region(infcx, body, mir_def_id, fr, placeholder);
+                }
+
+                NLLRegionVariableOrigin::Existential { .. } => {
+                    // nothing to check here
+                }
+            }
+        }
+
+        // Emit outlives suggestions
+        outlives_suggestion.add_suggestion(body, self, infcx, errors_buffer, region_naming);
+    }
+
     /// Checks the final value for the free region `fr` to see if it
     /// grew too large. In particular, examine what `end(X)` points
     /// wound up in `fr`'s final value; for each `end(X)` where `X !=
@@ -1474,8 +1597,37 @@
             return None;
         }
 
+        self.report_or_propagate_universal_region_error(
+            longer_fr,
+            shorter_fr,
+            infcx,
+            body,
+            local_names,
+            upvars,
+            mir_def_id,
+            propagated_outlives_requirements,
+            outlives_suggestion,
+            errors_buffer,
+            region_naming,
+        )
+    }
+
+    fn report_or_propagate_universal_region_error(
+        &self,
+        longer_fr: RegionVid,
+        shorter_fr: RegionVid,
+        infcx: &InferCtxt<'_, 'tcx>,
+        body: &Body<'tcx>,
+        local_names: &IndexVec<Local, Option<Symbol>>,
+        upvars: &[Upvar],
+        mir_def_id: DefId,
+        propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
+        outlives_suggestion: &mut OutlivesSuggestionBuilder<'_>,
+        errors_buffer: &mut Vec<Diagnostic>,
+        region_naming: &mut RegionErrorNamingCtx,
+    ) -> Option<ErrorReported> {
         debug!(
-            "check_universal_region_relation: fr={:?} does not outlive shorter_fr={:?}",
+            "report_or_propagate_universal_region_error: fr={:?} does not outlive shorter_fr={:?}",
             longer_fr, shorter_fr,
         );
 
@@ -1484,9 +1636,9 @@
             // We'll call it `fr-` -- it's ever so slightly smaller than
             // `longer_fr`.
 
-            if let Some(fr_minus) = self.universal_region_relations.non_local_lower_bound(longer_fr)
-            {
-                debug!("check_universal_region: fr_minus={:?}", fr_minus);
+            if let Some(fr_minus) =
+                self.universal_region_relations.non_local_lower_bound(longer_fr) {
+                debug!("report_or_propagate_universal_region_error: fr_minus={:?}", fr_minus);
 
                 let blame_span_category =
                     self.find_outlives_blame_span(body, longer_fr,
@@ -1495,9 +1647,13 @@
                 // Grow `shorter_fr` until we find some non-local regions. (We
                 // always will.)  We'll call them `shorter_fr+` -- they're ever
                 // so slightly larger than `shorter_fr`.
-                let shorter_fr_plus =
-                    self.universal_region_relations.non_local_upper_bounds(&shorter_fr);
-                debug!("check_universal_region: shorter_fr_plus={:?}", shorter_fr_plus);
+                let shorter_fr_plus = self
+                    .universal_region_relations
+                    .non_local_upper_bounds(&shorter_fr);
+                debug!(
+                    "report_or_propagate_universal_region_error: shorter_fr_plus={:?}",
+                    shorter_fr_plus
+                );
                 for &&fr in &shorter_fr_plus {
                     // Push the constraint `fr-: shorter_fr+`
                     propagated_outlives_requirements.push(ClosureOutlivesRequirement {
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/values.rs b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
index b4414c5..0bf0cd3 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/values.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
@@ -1,4 +1,4 @@
-use rustc::mir::{BasicBlock, Location, Body, ReadOnlyBodyCache};
+use rustc::mir::{BasicBlock, Location, Body, ReadOnlyBodyAndCache};
 use rustc::ty::{self, RegionVid};
 use rustc_index::bit_set::{HybridBitSet, SparseBitMatrix};
 use rustc_data_structures::fx::FxHashMap;
@@ -92,7 +92,7 @@
     /// Pushes all predecessors of `index` onto `stack`.
     crate fn push_predecessors(
         &self,
-        body: ReadOnlyBodyCache<'_, '_>,
+        body: ReadOnlyBodyAndCache<'_, '_>,
         index: PointIndex,
         stack: &mut Vec<PointIndex>,
     ) {
diff --git a/src/librustc_mir/borrow_check/nll/renumber.rs b/src/librustc_mir/borrow_check/nll/renumber.rs
index db15d2c..ba323b1 100644
--- a/src/librustc_mir/borrow_check/nll/renumber.rs
+++ b/src/librustc_mir/borrow_check/nll/renumber.rs
@@ -1,6 +1,6 @@
 use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
-use rustc::mir::{BodyCache, Location, PlaceElem, Promoted};
+use rustc::mir::{BodyAndCache, Location, PlaceElem, Promoted};
 use rustc::mir::visit::{MutVisitor, TyContext};
 use rustc::infer::{InferCtxt, NLLRegionVariableOrigin};
 use rustc_index::vec::IndexVec;
@@ -9,8 +9,8 @@
 /// inference variables, returning the number of variables created.
 pub fn renumber_mir<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
-    body: &mut BodyCache<'tcx>,
-    promoted: &mut IndexVec<Promoted, BodyCache<'tcx>>,
+    body: &mut BodyAndCache<'tcx>,
+    promoted: &mut IndexVec<Promoted, BodyAndCache<'tcx>>,
 ) {
     debug!("renumber_mir()");
     debug!("renumber_mir: body.arg_count={:?}", body.arg_count);
diff --git a/src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs b/src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs
index d18a8e8..8bb6838 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs
@@ -217,6 +217,11 @@
     crate fn regions_outlived_by(&self, fr1: RegionVid) -> Vec<&RegionVid> {
         self.outlives.reachable_from(&fr1)
     }
+
+    /// Returns the _non-transitive_ set of known `outlives` constraints between free regions.
+    crate fn known_outlives(&self) -> impl Iterator<Item=(&RegionVid, &RegionVid)> {
+        self.outlives.base_edges()
+    }
 }
 
 struct UniversalRegionRelationsBuilder<'this, 'tcx> {
diff --git a/src/librustc_mir/borrow_check/nll/type_check/liveness/local_use_map.rs b/src/librustc_mir/borrow_check/nll/type_check/liveness/local_use_map.rs
index d6aa314..ab8c6f2 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/liveness/local_use_map.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/liveness/local_use_map.rs
@@ -1,7 +1,7 @@
 use crate::borrow_check::nll::region_infer::values::{PointIndex, RegionValueElements};
 use crate::util::liveness::{categorize, DefUse};
 use rustc::mir::visit::{PlaceContext, Visitor};
-use rustc::mir::{Local, Location, ReadOnlyBodyCache};
+use rustc::mir::{Local, Location, ReadOnlyBodyAndCache};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_data_structures::vec_linked_list as vll;
 
@@ -60,7 +60,7 @@
     crate fn build(
         live_locals: &Vec<Local>,
         elements: &RegionValueElements,
-        body: ReadOnlyBodyCache<'_, '_>,
+        body: ReadOnlyBodyAndCache<'_, '_>,
     ) -> Self {
         let nones = IndexVec::from_elem_n(None, body.local_decls.len());
         let mut local_use_map = LocalUseMap {
diff --git a/src/librustc_mir/borrow_check/nll/type_check/liveness/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/liveness/mod.rs
index dfd505f..8f8e9af 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/liveness/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/liveness/mod.rs
@@ -7,7 +7,7 @@
 use crate::dataflow::move_paths::MoveData;
 use crate::dataflow::FlowAtLocation;
 use crate::dataflow::MaybeInitializedPlaces;
-use rustc::mir::{Body, Local, ReadOnlyBodyCache};
+use rustc::mir::{Body, Local, ReadOnlyBodyAndCache};
 use rustc::ty::{RegionVid, TyCtxt};
 use rustc_data_structures::fx::FxHashSet;
 use std::rc::Rc;
@@ -28,7 +28,7 @@
 /// performed before
 pub(super) fn generate<'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     elements: &Rc<RegionValueElements>,
     flow_inits: &mut FlowAtLocation<'tcx, MaybeInitializedPlaces<'_, 'tcx>>,
     move_data: &MoveData<'tcx>,
diff --git a/src/librustc_mir/borrow_check/nll/type_check/liveness/polonius.rs b/src/librustc_mir/borrow_check/nll/type_check/liveness/polonius.rs
index e67de6c..810811f 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/liveness/polonius.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/liveness/polonius.rs
@@ -3,7 +3,7 @@
 use crate::dataflow::move_paths::{LookupResult, MoveData};
 use crate::util::liveness::{categorize, DefUse};
 use rustc::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
-use rustc::mir::{Local, Location, Place, ReadOnlyBodyCache};
+use rustc::mir::{Local, Location, Place, ReadOnlyBodyAndCache};
 use rustc::ty::subst::GenericArg;
 use rustc::ty::Ty;
 
@@ -97,7 +97,7 @@
 
 pub(super) fn populate_access_facts(
     typeck: &mut TypeChecker<'_, 'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     location_table: &LocationTable,
     move_data: &MoveData<'_>,
     drop_used: &mut Vec<(Local, Location)>,
diff --git a/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs b/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
index 229cbed..ba6fd75 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
@@ -7,7 +7,7 @@
 use crate::dataflow::move_paths::MoveData;
 use crate::dataflow::{FlowAtLocation, FlowsAtLocation, MaybeInitializedPlaces};
 use rustc::infer::canonical::QueryRegionConstraints;
-use rustc::mir::{BasicBlock, ConstraintCategory, Local, Location, ReadOnlyBodyCache};
+use rustc::mir::{BasicBlock, ConstraintCategory, Local, Location, ReadOnlyBodyAndCache};
 use rustc::traits::query::dropck_outlives::DropckOutlivesResult;
 use rustc::traits::query::type_op::outlives::DropckOutlives;
 use rustc::traits::query::type_op::TypeOp;
@@ -32,7 +32,7 @@
 /// this respects `#[may_dangle]` annotations).
 pub(super) fn trace(
     typeck: &mut TypeChecker<'_, 'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     elements: &Rc<RegionValueElements>,
     flow_inits: &mut FlowAtLocation<'tcx, MaybeInitializedPlaces<'_, 'tcx>>,
     move_data: &MoveData<'tcx>,
@@ -71,7 +71,7 @@
     elements: &'me RegionValueElements,
 
     /// MIR we are analyzing.
-    body: ReadOnlyBodyCache<'me, 'tcx>,
+    body: ReadOnlyBodyAndCache<'me, 'tcx>,
 
     /// Mapping to/from the various indices used for initialization tracking.
     move_data: &'me MoveData<'tcx>,
@@ -249,7 +249,7 @@
         // Reverse DFS. But for drops, we do it a bit differently.
         // The stack only ever stores *terminators of blocks*. Within
         // a block, we walk back the statements in an inner loop.
-        'next_block: while let Some(term_point) = self.stack.pop() {
+        while let Some(term_point) = self.stack.pop() {
             self.compute_drop_live_points_for_block(mpi, term_point);
         }
     }
diff --git a/src/librustc_mir/borrow_check/nll/type_check/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
index de30420..8d4e76c 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
@@ -117,8 +117,8 @@
 pub(crate) fn type_check<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
-    promoted: &IndexVec<Promoted, ReadOnlyBodyCache<'_, 'tcx>>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
+    promoted: &IndexVec<Promoted, ReadOnlyBodyAndCache<'_, 'tcx>>,
     mir_def_id: DefId,
     universal_regions: &Rc<UniversalRegions<'tcx>>,
     location_table: &LocationTable,
@@ -196,8 +196,8 @@
     infcx: &'a InferCtxt<'a, 'tcx>,
     mir_def_id: DefId,
     param_env: ty::ParamEnv<'tcx>,
-    body: ReadOnlyBodyCache<'a, 'tcx>,
-    promoted: &'a IndexVec<Promoted, ReadOnlyBodyCache<'_, 'tcx>>,
+    body: ReadOnlyBodyAndCache<'a, 'tcx>,
+    promoted: &'a IndexVec<Promoted, ReadOnlyBodyAndCache<'_, 'tcx>>,
     region_bound_pairs: &'a RegionBoundPairs<'tcx>,
     implicit_region_bound: ty::Region<'tcx>,
     borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>,
@@ -206,7 +206,7 @@
 ) -> R {
     let mut checker = TypeChecker::new(
         infcx,
-        body.body(),
+        *body,
         mir_def_id,
         param_env,
         region_bound_pairs,
@@ -215,7 +215,7 @@
         universal_region_relations,
     );
     let errors_reported = {
-        let mut verifier = TypeVerifier::new(&mut checker, body.body(), promoted);
+        let mut verifier = TypeVerifier::new(&mut checker, *body, promoted);
         verifier.visit_body(body);
         verifier.errors_reported
     };
@@ -272,7 +272,7 @@
 struct TypeVerifier<'a, 'b, 'tcx> {
     cx: &'a mut TypeChecker<'b, 'tcx>,
     body: &'b Body<'tcx>,
-    promoted: &'b IndexVec<Promoted, ReadOnlyBodyCache<'b, 'tcx>>,
+    promoted: &'b IndexVec<Promoted, ReadOnlyBodyAndCache<'b, 'tcx>>,
     last_span: Span,
     mir_def_id: DefId,
     errors_reported: bool,
@@ -396,7 +396,7 @@
         }
     }
 
-    fn visit_body(&mut self, body: ReadOnlyBodyCache<'_, 'tcx>) {
+    fn visit_body(&mut self, body: ReadOnlyBodyAndCache<'_, 'tcx>) {
         self.sanitize_type(&"return type", body.return_ty());
         for local_decl in &body.local_decls {
             self.sanitize_type(local_decl, local_decl.ty);
@@ -412,7 +412,7 @@
     fn new(
         cx: &'a mut TypeChecker<'b, 'tcx>,
         body: &'b Body<'tcx>,
-        promoted: &'b IndexVec<Promoted, ReadOnlyBodyCache<'b, 'tcx>>,
+        promoted: &'b IndexVec<Promoted, ReadOnlyBodyAndCache<'b, 'tcx>>,
     ) -> Self {
         TypeVerifier {
             body,
@@ -548,14 +548,14 @@
 
     fn sanitize_promoted(
         &mut self,
-        promoted_body: ReadOnlyBodyCache<'b, 'tcx>,
+        promoted_body: ReadOnlyBodyAndCache<'b, 'tcx>,
         location: Location
     ) {
         // Determine the constraints from the promoted MIR by running the type
         // checker on the promoted MIR, then transfer the constraints back to
         // the main MIR, changing the locations to the provided location.
 
-        let parent_body = mem::replace(&mut self.body, promoted_body.body());
+        let parent_body = mem::replace(&mut self.body, *promoted_body);
 
         // Use new sets of constraints and closure bounds so that we can
         // modify their locations.
@@ -1378,7 +1378,7 @@
 
     fn check_stmt(
         &mut self,
-        body: ReadOnlyBodyCache<'_, 'tcx>,
+        body: ReadOnlyBodyAndCache<'_, 'tcx>,
         stmt: &Statement<'tcx>,
         location: Location)
     {
@@ -1994,7 +1994,7 @@
 
     fn check_rvalue(
         &mut self,
-        body: ReadOnlyBodyCache<'_, 'tcx>,
+        body: ReadOnlyBodyAndCache<'_, 'tcx>,
         rvalue: &Rvalue<'tcx>,
         location: Location)
     {
@@ -2766,7 +2766,7 @@
         })
     }
 
-    fn typeck_mir(&mut self, body: ReadOnlyBodyCache<'_, 'tcx>) {
+    fn typeck_mir(&mut self, body: ReadOnlyBodyAndCache<'_, 'tcx>) {
         self.last_span = body.span;
         debug!("run_on_mir: {:?}", body.span);
 
diff --git a/src/librustc_mir/borrow_check/prefixes.rs b/src/librustc_mir/borrow_check/prefixes.rs
index b58bf73..248faa5 100644
--- a/src/librustc_mir/borrow_check/prefixes.rs
+++ b/src/librustc_mir/borrow_check/prefixes.rs
@@ -11,7 +11,7 @@
 
 use rustc::hir;
 use rustc::ty::{self, TyCtxt};
-use rustc::mir::{Place, PlaceBase, PlaceRef, ProjectionElem, ReadOnlyBodyCache};
+use rustc::mir::{Place, PlaceBase, PlaceRef, ProjectionElem, ReadOnlyBodyAndCache};
 
 pub trait IsPrefixOf<'cx, 'tcx> {
     fn is_prefix_of(&self, other: PlaceRef<'cx, 'tcx>) -> bool;
@@ -26,7 +26,7 @@
 }
 
 pub(super) struct Prefixes<'cx, 'tcx> {
-    body: ReadOnlyBodyCache<'cx, 'tcx>,
+    body: ReadOnlyBodyAndCache<'cx, 'tcx>,
     tcx: TyCtxt<'tcx>,
     kind: PrefixSet,
     next: Option<PlaceRef<'cx, 'tcx>>,
diff --git a/src/librustc_mir/build/matches/test.rs b/src/librustc_mir/build/matches/test.rs
index c893d6f..e320811 100644
--- a/src/librustc_mir/build/matches/test.rs
+++ b/src/librustc_mir/build/matches/test.rs
@@ -680,7 +680,7 @@
                     }
                 })();
 
-                if no_overlap == Some(true) {
+                if let Some(true) = no_overlap {
                     // Testing range does not overlap with pattern range,
                     // so the pattern can be matched only if this test fails.
                     Some(1)
@@ -690,7 +690,7 @@
             }
 
             (&TestKind::Range(range), &PatKind::Constant { value }) => {
-                if self.const_range_contains(range, value) == Some(false) {
+                if let Some(false) = self.const_range_contains(range, value) {
                     // `value` is not contained in the testing range,
                     // so `value` can be matched only if this test fails.
                     Some(1)
diff --git a/src/librustc_mir/build/mod.rs b/src/librustc_mir/build/mod.rs
index b84461d..0009eb4 100644
--- a/src/librustc_mir/build/mod.rs
+++ b/src/librustc_mir/build/mod.rs
@@ -24,7 +24,7 @@
 use super::lints;
 
 /// Construct the MIR for a given `DefId`.
-pub fn mir_build(tcx: TyCtxt<'_>, def_id: DefId) -> BodyCache<'_> {
+pub fn mir_build(tcx: TyCtxt<'_>, def_id: DefId) -> BodyAndCache<'_> {
     let id = tcx.hir().as_local_hir_id(def_id).unwrap();
 
     // Figure out what primary body this item has.
@@ -196,7 +196,7 @@
 
         lints::check(tcx, &body, def_id);
 
-        let mut body = BodyCache::new(body);
+        let mut body = BodyAndCache::new(body);
         body.ensure_predecessors();
         body
     })
diff --git a/src/librustc_mir/const_eval.rs b/src/librustc_mir/const_eval.rs
index 968a8a7..b219fec 100644
--- a/src/librustc_mir/const_eval.rs
+++ b/src/librustc_mir/const_eval.rs
@@ -9,11 +9,10 @@
 
 use rustc::hir::def::DefKind;
 use rustc::hir::def_id::DefId;
-use rustc::middle::lang_items::PanicLocationLangItem;
 use rustc::mir::interpret::{ConstEvalErr, ErrorHandled, ScalarMaybeUndef};
 use rustc::mir;
 use rustc::ty::{self, Ty, TyCtxt, subst::Subst};
-use rustc::ty::layout::{self, LayoutOf, VariantIdx};
+use rustc::ty::layout::{self, HasTyCtxt, LayoutOf, VariantIdx};
 use rustc::traits::Reveal;
 use rustc_data_structures::fx::FxHashMap;
 use crate::interpret::eval_nullary_intrinsic;
@@ -348,7 +347,11 @@
                 //
                 // For the moment we only do this for functions which take no arguments
                 // (or all arguments are ZSTs) so that we don't memoize too much.
-                if args.iter().all(|a| a.layout.is_zst()) {
+                //
+                // Because `#[track_caller]` adds an implicit non-ZST argument, we also cannot
+                // perform this optimization on items tagged with it.
+                let no_implicit_args = !instance.def.requires_caller_location(ecx.tcx());
+                if args.iter().all(|a| a.layout.is_zst()) && no_implicit_args {
                     let gid = GlobalId { instance, promoted: None };
                     ecx.eval_const_fn_call(gid, ret)?;
                     return Ok(None);
@@ -366,7 +369,7 @@
         }
         // This is a const fn. Call it.
         Ok(Some(match ecx.load_mir(instance.def, None) {
-            Ok(body) => body.body(),
+            Ok(body) => *body,
             Err(err) => {
                 if let err_unsup!(NoMirFor(ref path)) = err.kind {
                     return Err(
@@ -559,11 +562,7 @@
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::reveal_all());
 
-    let loc_ty = tcx.mk_imm_ref(
-        tcx.lifetimes.re_static,
-        tcx.type_of(tcx.require_lang_item(PanicLocationLangItem, None))
-            .subst(tcx, tcx.mk_substs([tcx.lifetimes.re_static.into()].iter())),
-    );
+    let loc_ty = tcx.caller_location_ty();
     let loc_place = ecx.alloc_caller_location(file, line, col);
     intern_const_alloc_recursive(&mut ecx, None, loc_place).unwrap();
     let loc_const = ty::Const {
@@ -743,7 +742,7 @@
 
     let res = ecx.load_mir(cid.instance.def, cid.promoted);
     res.and_then(
-        |body| eval_body_using_ecx(&mut ecx, cid, body.body())
+        |body| eval_body_using_ecx(&mut ecx, cid, *body)
     ).and_then(|place| {
         Ok(RawConst {
             alloc_id: place.ptr.assert_ptr().alloc_id,
diff --git a/src/librustc_mir/dataflow/impls/storage_liveness.rs b/src/librustc_mir/dataflow/impls/storage_liveness.rs
index c4b97d1..b8abe6d 100644
--- a/src/librustc_mir/dataflow/impls/storage_liveness.rs
+++ b/src/librustc_mir/dataflow/impls/storage_liveness.rs
@@ -75,20 +75,20 @@
 /// Dataflow analysis that determines whether each local requires storage at a
 /// given location; i.e. whether its storage can go away without being observed.
 pub struct RequiresStorage<'mir, 'tcx> {
-    body: ReadOnlyBodyCache<'mir, 'tcx>,
+    body: ReadOnlyBodyAndCache<'mir, 'tcx>,
     borrowed_locals:
         RefCell<DataflowResultsRefCursor<'mir, 'tcx, HaveBeenBorrowedLocals<'mir, 'tcx>>>,
 }
 
 impl<'mir, 'tcx: 'mir> RequiresStorage<'mir, 'tcx> {
     pub fn new(
-        body: ReadOnlyBodyCache<'mir, 'tcx>,
+        body: ReadOnlyBodyAndCache<'mir, 'tcx>,
         borrowed_locals: &'mir DataflowResults<'tcx, HaveBeenBorrowedLocals<'mir, 'tcx>>,
     ) -> Self {
         RequiresStorage {
             body,
             borrowed_locals: RefCell::new(
-                DataflowResultsCursor::new(borrowed_locals, body.body())
+                DataflowResultsCursor::new(borrowed_locals, *body)
             ),
         }
     }
diff --git a/src/librustc_mir/hair/pattern/mod.rs b/src/librustc_mir/hair/pattern/mod.rs
index 92c7178..0086c3b 100644
--- a/src/librustc_mir/hair/pattern/mod.rs
+++ b/src/librustc_mir/hair/pattern/mod.rs
@@ -1154,13 +1154,7 @@
 ) -> Option<Ordering> {
     trace!("compare_const_vals: {:?}, {:?}", a, b);
 
-    let from_bool = |v: bool| {
-        if v {
-            Some(Ordering::Equal)
-        } else {
-            None
-        }
-    };
+    let from_bool = |v: bool| v.then_some(Ordering::Equal);
 
     let fallback = || from_bool(a == b);
 
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 9af47f3..653718c 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -312,7 +312,7 @@
         &self,
         instance: ty::InstanceDef<'tcx>,
         promoted: Option<mir::Promoted>,
-    ) -> InterpResult<'tcx, mir::ReadOnlyBodyCache<'tcx, 'tcx>> {
+    ) -> InterpResult<'tcx, mir::ReadOnlyBodyAndCache<'tcx, 'tcx>> {
         // do not continue if typeck errors occurred (can only occur in local crate)
         let did = instance.def_id();
         if did.is_local()
diff --git a/src/librustc_mir/interpret/intrinsics.rs b/src/librustc_mir/interpret/intrinsics.rs
index ad5df5a..67f0aed 100644
--- a/src/librustc_mir/interpret/intrinsics.rs
+++ b/src/librustc_mir/interpret/intrinsics.rs
@@ -112,6 +112,7 @@
         // `src/librustc/ty/constness.rs`
         match intrinsic_name {
             sym::caller_location => {
+                let span = self.find_closest_untracked_caller_location().unwrap_or(span);
                 let location = self.alloc_caller_location_for_span(span);
                 self.write_scalar(location.ptr, dest)?;
             }
diff --git a/src/librustc_mir/interpret/intrinsics/caller_location.rs b/src/librustc_mir/interpret/intrinsics/caller_location.rs
index ecf4b7a..ec843ef 100644
--- a/src/librustc_mir/interpret/intrinsics/caller_location.rs
+++ b/src/librustc_mir/interpret/intrinsics/caller_location.rs
@@ -6,6 +6,21 @@
 use crate::interpret::{Scalar, MemoryKind, MPlaceTy, intrinsics::{InterpCx, Machine}};
 
 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
+    /// Walks up the callstack from the intrinsic's callsite, searching for the first frame which is
+    /// not `#[track_caller]`.
+    crate fn find_closest_untracked_caller_location(&self) -> Option<Span> {
+        let mut caller_span = None;
+        for next_caller in self.stack.iter().rev() {
+            if !next_caller.instance.def.requires_caller_location(*self.tcx) {
+                return caller_span;
+            }
+            caller_span = Some(next_caller.span);
+        }
+
+        caller_span
+    }
+
+    /// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.
     crate fn alloc_caller_location(
         &mut self,
         filename: Symbol,
diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index ee7fb18..8f177ad 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -324,7 +324,7 @@
         size: Size,
         align: Align,
     ) -> InterpResult<'tcx, Option<Pointer<M::PointerTag>>> {
-        let align = if M::CHECK_ALIGN { Some(align) } else { None };
+        let align = M::CHECK_ALIGN.then_some(align);
         self.check_ptr_access_align(sptr, size, align, CheckInAllocMsg::MemoryAccessTest)
     }
 
diff --git a/src/librustc_mir/interpret/operator.rs b/src/librustc_mir/interpret/operator.rs
index 176b084..6800429 100644
--- a/src/librustc_mir/interpret/operator.rs
+++ b/src/librustc_mir/interpret/operator.rs
@@ -177,8 +177,8 @@
                 return Ok((Scalar::from_bool(op(&l, &r)), false, self.tcx.types.bool));
             }
             let op: Option<fn(i128, i128) -> (i128, bool)> = match bin_op {
-                Div if r == 0 => throw_panic!(DivisionByZero),
-                Rem if r == 0 => throw_panic!(RemainderByZero),
+                Div if r == 0 => throw_ub!(DivisionByZero),
+                Rem if r == 0 => throw_ub!(RemainderByZero),
                 Div => Some(i128::overflowing_div),
                 Rem => Some(i128::overflowing_rem),
                 Add => Some(i128::overflowing_add),
@@ -234,8 +234,8 @@
                     Add => u128::overflowing_add,
                     Sub => u128::overflowing_sub,
                     Mul => u128::overflowing_mul,
-                    Div if r == 0 => throw_panic!(DivisionByZero),
-                    Rem if r == 0 => throw_panic!(RemainderByZero),
+                    Div if r == 0 => throw_ub!(DivisionByZero),
+                    Rem if r == 0 => throw_ub!(RemainderByZero),
                     Div => u128::overflowing_div,
                     Rem => u128::overflowing_rem,
                     _ => bug!(),
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index 902472d..a600eb1 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -384,10 +384,8 @@
             layout::FieldPlacement::Array { stride, .. } => {
                 let len = base.len(self)?;
                 if field >= len {
-                    // This can be violated because the index (field) can be a runtime value
-                    // provided by the user.
-                    debug!("tried to access element {} of array/slice with length {}", field, len);
-                    throw_panic!(BoundsCheck { len, index: field });
+                    // This can only be reached in ConstProp and non-rustc-MIR.
+                    throw_ub!(BoundsCheckFailed { len, index: field });
                 }
                 stride * field
             }
diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs
index d749333..55b9427 100644
--- a/src/librustc_mir/interpret/step.rs
+++ b/src/librustc_mir/interpret/step.rs
@@ -157,9 +157,9 @@
             }
 
             BinaryOp(bin_op, ref left, ref right) => {
-                let layout = if binop_left_homogeneous(bin_op) { Some(dest.layout) } else { None };
+                let layout = binop_left_homogeneous(bin_op).then_some(dest.layout);
                 let left = self.read_immediate(self.eval_operand(left, layout)?)?;
-                let layout = if binop_right_homogeneous(bin_op) { Some(left.layout) } else { None };
+                let layout = binop_right_homogeneous(bin_op).then_some(left.layout);
                 let right = self.read_immediate(self.eval_operand(right, layout)?)?;
                 self.binop_ignore_overflow(
                     bin_op,
@@ -172,7 +172,7 @@
             CheckedBinaryOp(bin_op, ref left, ref right) => {
                 // Due to the extra boolean in the result, we can never reuse the `dest.layout`.
                 let left = self.read_immediate(self.eval_operand(left, None)?)?;
-                let layout = if binop_right_homogeneous(bin_op) { Some(left.layout) } else { None };
+                let layout = binop_right_homogeneous(bin_op).then_some(left.layout);
                 let right = self.read_immediate(self.eval_operand(right, layout)?)?;
                 self.binop_with_overflow(
                     bin_op,
diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs
index f4fb9a5..42b72b6 100644
--- a/src/librustc_mir/lib.rs
+++ b/src/librustc_mir/lib.rs
@@ -8,6 +8,7 @@
 #![feature(in_band_lifetimes)]
 #![feature(inner_deref)]
 #![feature(slice_patterns)]
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]
@@ -27,7 +28,6 @@
 #![feature(associated_type_bounds)]
 #![feature(range_is_empty)]
 #![feature(stmt_expr_attributes)]
-#![feature(bool_to_option)]
 #![feature(trait_alias)]
 #![feature(matches_macro)]
 
diff --git a/src/librustc_mir/monomorphize/partitioning.rs b/src/librustc_mir/monomorphize/partitioning.rs
index 42f0877..591f220 100644
--- a/src/librustc_mir/monomorphize/partitioning.rs
+++ b/src/librustc_mir/monomorphize/partitioning.rs
@@ -761,11 +761,7 @@
             .iter()
             .map(|part| part.data.as_symbol());
 
-        let volatile_suffix = if volatile {
-            Some("volatile")
-        } else {
-            None
-        };
+        let volatile_suffix = volatile.then_some("volatile");
 
         name_builder.build_cgu_name(def_path.krate, components, volatile_suffix)
     }).clone()
diff --git a/src/librustc_mir/shim.rs b/src/librustc_mir/shim.rs
index 5b208dd..47b0804 100644
--- a/src/librustc_mir/shim.rs
+++ b/src/librustc_mir/shim.rs
@@ -26,7 +26,7 @@
     providers.mir_shims = make_shim;
 }
 
-fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> &'tcx BodyCache<'tcx> {
+fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> &'tcx BodyAndCache<'tcx> {
     debug!("make_shim({:?})", instance);
 
     let mut result = match instance {
@@ -170,7 +170,7 @@
 
 fn build_drop_shim<'tcx>(
     tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>
-) -> BodyCache<'tcx> {
+) -> BodyAndCache<'tcx> {
     debug!("build_drop_shim(def_id={:?}, ty={:?})", def_id, ty);
 
     // Check if this is a generator, if so, return the drop glue for it
@@ -208,7 +208,7 @@
         sig.inputs().len(),
         span);
 
-    let mut body = BodyCache::new(body);
+    let mut body = BodyAndCache::new(body);
 
     if let Some(..) = ty {
         // The first argument (index 0), but add 1 for the return value.
@@ -322,7 +322,11 @@
 }
 
 /// Builds a `Clone::clone` shim for `self_ty`. Here, `def_id` is `Clone::clone`.
-fn build_clone_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> BodyCache<'tcx> {
+fn build_clone_shim<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: DefId,
+    self_ty: Ty<'tcx>,
+) -> BodyAndCache<'tcx> {
     debug!("build_clone_shim(def_id={:?})", def_id);
 
     let param_env = tcx.param_env(def_id);
@@ -351,7 +355,7 @@
         }
     };
 
-    BodyCache::new(builder.into_mir())
+    BodyAndCache::new(builder.into_mir())
 }
 
 struct CloneShimBuilder<'tcx> {
@@ -712,7 +716,7 @@
     rcvr_adjustment: Adjustment,
     call_kind: CallKind,
     untuple_args: Option<&[Ty<'tcx>]>,
-) -> BodyCache<'tcx> {
+) -> BodyAndCache<'tcx> {
     debug!("build_call_shim(instance={:?}, rcvr_adjustment={:?}, \
             call_kind={:?}, untuple_args={:?})",
            instance, rcvr_adjustment, call_kind, untuple_args);
@@ -853,10 +857,10 @@
     if let Abi::RustCall = sig.abi {
         body.spread_arg = Some(Local::new(sig.inputs().len()));
     }
-    BodyCache::new(body)
+    BodyAndCache::new(body)
 }
 
-pub fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> &BodyCache<'_> {
+pub fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> &BodyAndCache<'_> {
     debug_assert!(tcx.is_constructor(ctor_id));
 
     let span = tcx.hir().span_if_local(ctor_id)
@@ -940,7 +944,7 @@
         |_, _| Ok(()),
     );
 
-    let mut body = BodyCache::new(body);
+    let mut body = BodyAndCache::new(body);
     body.ensure_predecessors();
     tcx.arena.alloc(body)
 }
diff --git a/src/librustc_mir/transform/add_call_guards.rs b/src/librustc_mir/transform/add_call_guards.rs
index 35238e2..d1832eb 100644
--- a/src/librustc_mir/transform/add_call_guards.rs
+++ b/src/librustc_mir/transform/add_call_guards.rs
@@ -32,14 +32,14 @@
 
 impl<'tcx> MirPass<'tcx> for AddCallGuards {
     fn run_pass(
-        &self, _tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, _tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         self.add_call_guards(body);
     }
 }
 
 impl AddCallGuards {
-    pub fn add_call_guards(&self, body: &mut BodyCache<'_>) {
+    pub fn add_call_guards(&self, body: &mut BodyAndCache<'_>) {
         let pred_count: IndexVec<_, _> = body.predecessors().iter().map(|ps| ps.len()).collect();
 
         // We need a place to store the new blocks generated
diff --git a/src/librustc_mir/transform/add_moves_for_packed_drops.rs b/src/librustc_mir/transform/add_moves_for_packed_drops.rs
index 98c6a5e..861e7fe 100644
--- a/src/librustc_mir/transform/add_moves_for_packed_drops.rs
+++ b/src/librustc_mir/transform/add_moves_for_packed_drops.rs
@@ -40,14 +40,14 @@
 pub struct AddMovesForPackedDrops;
 
 impl<'tcx> MirPass<'tcx> for AddMovesForPackedDrops {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         debug!("add_moves_for_packed_drops({:?} @ {:?})", src, body.span);
         add_moves_for_packed_drops(tcx, body, src.def_id());
     }
 }
 
 pub fn add_moves_for_packed_drops<'tcx>(
-    tcx: TyCtxt<'tcx>, body: &mut BodyCache<'tcx>, def_id: DefId
+    tcx: TyCtxt<'tcx>, body: &mut BodyAndCache<'tcx>, def_id: DefId
 ) {
     let patch = add_moves_for_packed_drops_patch(tcx, body, def_id);
     patch.apply(body);
diff --git a/src/librustc_mir/transform/add_retag.rs b/src/librustc_mir/transform/add_retag.rs
index e6ad37a..dc21c67 100644
--- a/src/librustc_mir/transform/add_retag.rs
+++ b/src/librustc_mir/transform/add_retag.rs
@@ -59,7 +59,7 @@
 }
 
 impl<'tcx> MirPass<'tcx> for AddRetag {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         if !tcx.sess.opts.debugging_opts.mir_emit_retag {
             return;
         }
diff --git a/src/librustc_mir/transform/check_consts/mod.rs b/src/librustc_mir/transform/check_consts/mod.rs
index 82ffafb..89672e8 100644
--- a/src/librustc_mir/transform/check_consts/mod.rs
+++ b/src/librustc_mir/transform/check_consts/mod.rs
@@ -20,7 +20,7 @@
 /// Information about the item currently being const-checked, as well as a reference to the global
 /// context.
 pub struct Item<'mir, 'tcx> {
-    pub body: mir::ReadOnlyBodyCache<'mir, 'tcx>,
+    pub body: mir::ReadOnlyBodyAndCache<'mir, 'tcx>,
     pub tcx: TyCtxt<'tcx>,
     pub def_id: DefId,
     pub param_env: ty::ParamEnv<'tcx>,
@@ -31,7 +31,7 @@
     pub fn new(
         tcx: TyCtxt<'tcx>,
         def_id: DefId,
-        body: mir::ReadOnlyBodyCache<'mir, 'tcx>,
+        body: mir::ReadOnlyBodyAndCache<'mir, 'tcx>,
     ) -> Self {
         let param_env = tcx.param_env(def_id);
         let const_kind = ConstKind::for_item(tcx, def_id);
diff --git a/src/librustc_mir/transform/check_consts/ops.rs b/src/librustc_mir/transform/check_consts/ops.rs
index aec3cf0..393ae94 100644
--- a/src/librustc_mir/transform/check_consts/ops.rs
+++ b/src/librustc_mir/transform/check_consts/ops.rs
@@ -1,7 +1,6 @@
 //! Concrete error types for all operations which may be invalid in a certain const context.
 
 use rustc::hir::def_id::DefId;
-use rustc::mir::BorrowKind;
 use rustc::session::config::nightly_options;
 use rustc::ty::TyCtxt;
 use syntax::feature_gate::feature_err;
@@ -181,38 +180,53 @@
 }
 
 #[derive(Debug)]
-pub struct MutBorrow(pub BorrowKind);
-impl NonConstOp for MutBorrow {
+pub struct CellBorrow;
+impl NonConstOp for CellBorrow {
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        let kind = self.0;
-        if let BorrowKind::Mut { .. } = kind {
-            let mut err = struct_span_err!(item.tcx.sess, span, E0017,
-                                           "references in {}s may only refer \
-                                            to immutable values", item.const_kind());
-            err.span_label(span, format!("{}s require immutable values",
-                                                item.const_kind()));
-            if item.tcx.sess.teach(&err.get_code().unwrap()) {
-                err.note("References in statics and constants may only refer \
-                          to immutable values.\n\n\
-                          Statics are shared everywhere, and if they refer to \
-                          mutable data one might violate memory safety since \
-                          holding multiple mutable references to shared data \
-                          is not allowed.\n\n\
-                          If you really want global mutable state, try using \
-                          static mut or a global UnsafeCell.");
-            }
-            err.emit();
-        } else {
-            span_err!(item.tcx.sess, span, E0492,
-                      "cannot borrow a constant which may contain \
-                       interior mutability, create a static instead");
+        span_err!(item.tcx.sess, span, E0492,
+            "cannot borrow a constant which may contain \
+            interior mutability, create a static instead");
+    }
+}
+
+#[derive(Debug)]
+pub struct MutBorrow;
+impl NonConstOp for MutBorrow {
+    fn feature_gate(tcx: TyCtxt<'_>) -> Option<bool> {
+        Some(tcx.features().const_mut_refs)
+    }
+
+    fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
+        let mut err = feature_err(
+            &item.tcx.sess.parse_sess,
+            sym::const_mut_refs,
+            span,
+            &format!("references in {}s may only refer \
+                      to immutable values", item.const_kind())
+        );
+        err.span_label(span, format!("{}s require immutable values",
+                                            item.const_kind()));
+        if item.tcx.sess.teach(&err.get_code().unwrap()) {
+            err.note("References in statics and constants may only refer \
+                      to immutable values.\n\n\
+                      Statics are shared everywhere, and if they refer to \
+                      mutable data one might violate memory safety since \
+                      holding multiple mutable references to shared data \
+                      is not allowed.\n\n\
+                      If you really want global mutable state, try using \
+                      static mut or a global UnsafeCell.");
         }
+        err.emit();
     }
 }
 
 #[derive(Debug)]
 pub struct MutDeref;
-impl NonConstOp for MutDeref {}
+impl NonConstOp for MutDeref {
+    fn feature_gate(tcx: TyCtxt<'_>) -> Option<bool> {
+        Some(tcx.features().const_mut_refs)
+    }
+}
 
 #[derive(Debug)]
 pub struct Panic;
diff --git a/src/librustc_mir/transform/check_consts/validation.rs b/src/librustc_mir/transform/check_consts/validation.rs
index f44bac1..6261315 100644
--- a/src/librustc_mir/transform/check_consts/validation.rs
+++ b/src/librustc_mir/transform/check_consts/validation.rs
@@ -40,7 +40,7 @@
         let results =
             dataflow::Engine::new(item.tcx, &item.body, item.def_id, dead_unwinds, analysis)
                 .iterate_to_fixpoint();
-        let cursor = dataflow::ResultsCursor::new(item.body.body(), results);
+        let cursor = dataflow::ResultsCursor::new(*item.body, results);
 
         let mut in_any_value_of_ty = BitSet::new_empty(item.body.local_decls.len());
         for (local, decl) in item.body.local_decls.iter_enumerated() {
@@ -175,13 +175,13 @@
             item.def_id,
             &item.tcx.get_attrs(item.def_id),
             &dead_unwinds,
-            old_dataflow::IndirectlyMutableLocals::new(item.tcx, item.body.body(), item.param_env),
+            old_dataflow::IndirectlyMutableLocals::new(item.tcx, *item.body, item.param_env),
             |_, local| old_dataflow::DebugFormatted::new(&local),
         );
 
         let indirectly_mutable = old_dataflow::DataflowResultsCursor::new(
             indirectly_mutable,
-            item.body.body(),
+            *item.body,
         );
 
         let qualifs = Qualifs {
@@ -359,7 +359,11 @@
                 };
 
                 if !is_allowed {
-                    self.check_op(ops::MutBorrow(kind));
+                    if let BorrowKind::Mut{ .. } = kind {
+                        self.check_op(ops::MutBorrow);
+                    } else {
+                        self.check_op(ops::CellBorrow);
+                    }
                 }
             }
 
@@ -384,7 +388,11 @@
                 );
 
                 if borrowed_place_has_mut_interior {
-                    self.check_op(ops::MutBorrow(kind));
+                    if let BorrowKind::Mut{ .. } = kind {
+                        self.check_op(ops::MutBorrow);
+                    } else {
+                        self.check_op(ops::CellBorrow);
+                    }
                 }
             }
 
@@ -451,7 +459,6 @@
             }
         }
     }
-
     fn visit_projection_elem(
         &mut self,
         place_base: &PlaceBase<'tcx>,
diff --git a/src/librustc_mir/transform/check_unsafety.rs b/src/librustc_mir/transform/check_unsafety.rs
index 2c45dcf..284285c 100644
--- a/src/librustc_mir/transform/check_unsafety.rs
+++ b/src/librustc_mir/transform/check_unsafety.rs
@@ -658,7 +658,7 @@
     let mut unsafe_blocks: Vec<_> = unsafe_blocks.into_iter().collect();
     unsafe_blocks.sort_by_cached_key(|(hir_id, _)| tcx.hir().hir_to_node_id(*hir_id));
     let used_unsafe: FxHashSet<_> = unsafe_blocks.iter()
-        .flat_map(|&&(id, used)| if used { Some(id) } else { None })
+        .flat_map(|&&(id, used)| used.then_some(id))
         .collect();
     for &(block_id, is_used) in unsafe_blocks {
         if !is_used {
diff --git a/src/librustc_mir/transform/cleanup_post_borrowck.rs b/src/librustc_mir/transform/cleanup_post_borrowck.rs
index d9dd7c9..34519bc 100644
--- a/src/librustc_mir/transform/cleanup_post_borrowck.rs
+++ b/src/librustc_mir/transform/cleanup_post_borrowck.rs
@@ -16,7 +16,7 @@
 //! [`FakeRead`]: rustc::mir::StatementKind::FakeRead
 //! [`Nop`]: rustc::mir::StatementKind::Nop
 
-use rustc::mir::{BodyCache, BorrowKind, Rvalue, Location};
+use rustc::mir::{BodyAndCache, BorrowKind, Rvalue, Location};
 use rustc::mir::{Statement, StatementKind};
 use rustc::mir::visit::MutVisitor;
 use rustc::ty::TyCtxt;
@@ -30,7 +30,7 @@
 
 impl<'tcx> MirPass<'tcx> for CleanupNonCodegenStatements {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         let mut delete = DeleteNonCodegenStatements { tcx };
         delete.visit_body(body);
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index 95de635..8843125 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -7,9 +7,9 @@
 use rustc::hir::def::DefKind;
 use rustc::hir::def_id::DefId;
 use rustc::mir::{
-    AggregateKind, Constant, Location, Place, PlaceBase, Body, BodyCache, Operand, Local, UnOp,
-    Rvalue, StatementKind, Statement, LocalKind, TerminatorKind, Terminator,  ClearCrossCrate,
-    SourceInfo, BinOp, SourceScope, SourceScopeData, LocalDecl, BasicBlock, ReadOnlyBodyCache,
+    AggregateKind, Constant, Location, Place, PlaceBase, Body, BodyAndCache, Operand, Local, UnOp,
+    Rvalue, StatementKind, Statement, LocalKind, TerminatorKind, Terminator, ClearCrossCrate,
+    SourceInfo, BinOp, SourceScope, SourceScopeData, LocalDecl, BasicBlock, ReadOnlyBodyAndCache,
     read_only, RETURN_PLACE
 };
 use rustc::mir::visit::{
@@ -43,7 +43,7 @@
 
 impl<'tcx> MirPass<'tcx> for ConstProp {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         // will be evaluated by miri and produce its errors there
         if source.promoted.is_some() {
@@ -296,7 +296,7 @@
 
 impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     fn new(
-        body: ReadOnlyBodyCache<'_, 'tcx>,
+        body: ReadOnlyBodyAndCache<'_, 'tcx>,
         dummy_body: &'mir Body<'tcx>,
         tcx: TyCtxt<'tcx>,
         source: MirSource<'tcx>,
@@ -690,7 +690,7 @@
 
 impl CanConstProp {
     /// returns true if `local` can be propagated
-    fn check(body: ReadOnlyBodyCache<'_, '_>) -> IndexVec<Local, bool> {
+    fn check(body: ReadOnlyBodyAndCache<'_, '_>) -> IndexVec<Local, bool> {
         let mut cpv = CanConstProp {
             can_const_prop: IndexVec::from_elem(true, &body.local_decls),
             found_assignment: IndexVec::from_elem(false, &body.local_decls),
diff --git a/src/librustc_mir/transform/copy_prop.rs b/src/librustc_mir/transform/copy_prop.rs
index 5e4caf2..272f6e9 100644
--- a/src/librustc_mir/transform/copy_prop.rs
+++ b/src/librustc_mir/transform/copy_prop.rs
@@ -20,7 +20,7 @@
 //! future.
 
 use rustc::mir::{
-    Constant, Local, LocalKind, Location, Place, Body, BodyCache, Operand, Rvalue,
+    Constant, Local, LocalKind, Location, Place, Body, BodyAndCache, Operand, Rvalue,
     StatementKind, read_only
 };
 use rustc::mir::visit::MutVisitor;
@@ -32,7 +32,7 @@
 
 impl<'tcx> MirPass<'tcx> for CopyPropagation {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         // We only run when the MIR optimization level is > 1.
         // This avoids a slow pass, and messing up debug info.
@@ -250,7 +250,7 @@
     }
 
     fn perform(self,
-               body: &mut BodyCache<'tcx>,
+               body: &mut BodyAndCache<'tcx>,
                def_use_analysis: &DefUseAnalysis,
                dest_local: Local,
                location: Location,
diff --git a/src/librustc_mir/transform/deaggregator.rs b/src/librustc_mir/transform/deaggregator.rs
index 933936e..cd77c9c 100644
--- a/src/librustc_mir/transform/deaggregator.rs
+++ b/src/librustc_mir/transform/deaggregator.rs
@@ -7,7 +7,7 @@
 
 impl<'tcx> MirPass<'tcx> for Deaggregator {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
         let local_decls = &*local_decls;
diff --git a/src/librustc_mir/transform/dump_mir.rs b/src/librustc_mir/transform/dump_mir.rs
index 13b3bb6..221ced3 100644
--- a/src/librustc_mir/transform/dump_mir.rs
+++ b/src/librustc_mir/transform/dump_mir.rs
@@ -5,7 +5,7 @@
 use std::fs::File;
 use std::io;
 
-use rustc::mir::{Body, BodyCache};
+use rustc::mir::{Body, BodyAndCache};
 use rustc::session::config::{OutputFilenames, OutputType};
 use rustc::ty::TyCtxt;
 use crate::transform::{MirPass, MirSource};
@@ -19,7 +19,7 @@
     }
 
     fn run_pass(
-        &self, _tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, _body: &mut BodyCache<'tcx>
+        &self, _tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, _body: &mut BodyAndCache<'tcx>
     ) {}
 }
 
diff --git a/src/librustc_mir/transform/elaborate_drops.rs b/src/librustc_mir/transform/elaborate_drops.rs
index 42daba9..9970752 100644
--- a/src/librustc_mir/transform/elaborate_drops.rs
+++ b/src/librustc_mir/transform/elaborate_drops.rs
@@ -21,7 +21,7 @@
 pub struct ElaborateDrops;
 
 impl<'tcx> MirPass<'tcx> for ElaborateDrops {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         debug!("elaborate_drops({:?} @ {:?})", src, body.span);
 
         let def_id = src.def_id();
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index 882e674..1eef3f2 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -62,7 +62,7 @@
 pub struct EraseRegions;
 
 impl<'tcx> MirPass<'tcx> for EraseRegions {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         EraseRegionsVisitor::new(tcx).visit_body(body);
     }
 }
diff --git a/src/librustc_mir/transform/generator.rs b/src/librustc_mir/transform/generator.rs
index e55737e..3d15d04 100644
--- a/src/librustc_mir/transform/generator.rs
+++ b/src/librustc_mir/transform/generator.rs
@@ -378,7 +378,7 @@
 fn make_generator_state_argument_indirect<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: DefId,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
 ) {
     let gen_ty = body.local_decls.raw[1].ty;
 
@@ -401,7 +401,7 @@
     DerefArgVisitor { tcx }.visit_body(body);
 }
 
-fn make_generator_state_argument_pinned<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyCache<'tcx>) {
+fn make_generator_state_argument_pinned<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyAndCache<'tcx>) {
     let ref_gen_ty = body.local_decls.raw[1].ty;
 
     let pin_did = tcx.lang_items().pin_type().unwrap();
@@ -418,7 +418,7 @@
 
 fn replace_result_variable<'tcx>(
     ret_ty: Ty<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     tcx: TyCtxt<'tcx>,
 ) -> Local {
     let source_info = source_info(body);
@@ -481,7 +481,7 @@
 
 fn locals_live_across_suspend_points(
     tcx: TyCtxt<'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     source: MirSource<'tcx>,
     movable: bool,
 ) -> LivenessInfo {
@@ -751,7 +751,7 @@
     upvars: &Vec<Ty<'tcx>>,
     interior: Ty<'tcx>,
     movable: bool,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
 ) -> (
     FxHashMap<Local, (Ty<'tcx>, VariantIdx, usize)>,
     GeneratorLayout<'tcx>,
@@ -830,7 +830,7 @@
 }
 
 fn insert_switch<'tcx>(
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     cases: Vec<(usize, BasicBlock)>,
     transform: &TransformVisitor<'tcx>,
     default: TerminatorKind<'tcx>,
@@ -862,7 +862,7 @@
 }
 
 fn elaborate_generator_drops<'tcx>(
-    tcx: TyCtxt<'tcx>, def_id: DefId, body: &mut BodyCache<'tcx>
+    tcx: TyCtxt<'tcx>, def_id: DefId, body: &mut BodyAndCache<'tcx>
 ) {
     use crate::util::elaborate_drops::{elaborate_drop, Unwind};
     use crate::util::patch::MirPatch;
@@ -928,9 +928,9 @@
     def_id: DefId,
     source: MirSource<'tcx>,
     gen_ty: Ty<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     drop_clean: BasicBlock,
-) -> BodyCache<'tcx> {
+) -> BodyAndCache<'tcx> {
     let mut body = body.clone();
 
     let source_info = source_info(&body);
@@ -997,7 +997,7 @@
 }
 
 fn insert_term_block<'tcx>(
-    body: &mut BodyCache<'tcx>, kind: TerminatorKind<'tcx>
+    body: &mut BodyAndCache<'tcx>, kind: TerminatorKind<'tcx>
 ) -> BasicBlock {
     let term_block = BasicBlock::new(body.basic_blocks().len());
     let source_info = source_info(body);
@@ -1014,7 +1014,7 @@
 
 fn insert_panic_block<'tcx>(
     tcx: TyCtxt<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     message: AssertMessage<'tcx>,
 ) -> BasicBlock {
     let assert_block = BasicBlock::new(body.basic_blocks().len());
@@ -1048,7 +1048,7 @@
     transform: TransformVisitor<'tcx>,
     def_id: DefId,
     source: MirSource<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
 ) {
     // Poison the generator when it unwinds
     for block in body.basic_blocks_mut() {
@@ -1101,7 +1101,7 @@
     }
 }
 
-fn insert_clean_drop(body: &mut BodyCache<'_>) -> BasicBlock {
+fn insert_clean_drop(body: &mut BodyAndCache<'_>) -> BasicBlock {
     let return_block = insert_term_block(body, TerminatorKind::Return);
 
     // Create a block to destroy an unresumed generators. This can only destroy upvars.
@@ -1125,7 +1125,7 @@
 }
 
 fn create_cases<'tcx, F>(
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     transform: &TransformVisitor<'tcx>,
     target: F,
 ) -> Vec<(usize, BasicBlock)>
@@ -1170,7 +1170,7 @@
 
 impl<'tcx> MirPass<'tcx> for StateTransform {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         let yield_ty = if let Some(yield_ty) = body.yield_ty {
             yield_ty
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index 79cb7fb..9763913 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -39,7 +39,7 @@
 
 impl<'tcx> MirPass<'tcx> for Inline {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         if tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
             Inliner { tcx, source }.run_pass(body);
@@ -53,7 +53,7 @@
 }
 
 impl Inliner<'tcx> {
-    fn run_pass(&self, caller_body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, caller_body: &mut BodyAndCache<'tcx>) {
         // Keep a queue of callsites to try inlining on. We take
         // advantage of the fact that queries detect cycles here to
         // allow us to try and fetch the fully optimized MIR of a
@@ -230,6 +230,11 @@
 
         let codegen_fn_attrs = tcx.codegen_fn_attrs(callsite.callee);
 
+        if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::TRACK_CALLER) {
+            debug!("`#[track_caller]` present - not inlining");
+            return false;
+        }
+
         let hinted = match codegen_fn_attrs.inline {
             // Just treat inline(always) as a hint for now,
             // there are cases that prevent inlining that we
@@ -380,8 +385,8 @@
 
     fn inline_call(&self,
                    callsite: CallSite<'tcx>,
-                   caller_body: &mut BodyCache<'tcx>,
-                   mut callee_body: BodyCache<'tcx>) -> bool {
+                   caller_body: &mut BodyAndCache<'tcx>,
+                   mut callee_body: BodyAndCache<'tcx>) -> bool {
         let terminator = caller_body[callsite.bb].terminator.take().unwrap();
         match terminator.kind {
             // FIXME: Handle inlining of diverging calls
@@ -517,7 +522,7 @@
         &self,
         args: Vec<Operand<'tcx>>,
         callsite: &CallSite<'tcx>,
-        caller_body: &mut BodyCache<'tcx>,
+        caller_body: &mut BodyAndCache<'tcx>,
     ) -> Vec<Local> {
         let tcx = self.tcx;
 
@@ -590,7 +595,7 @@
         &self,
         arg: Operand<'tcx>,
         callsite: &CallSite<'tcx>,
-        caller_body: &mut BodyCache<'tcx>,
+        caller_body: &mut BodyAndCache<'tcx>,
     ) -> Local {
         // FIXME: Analysis of the usage of the arguments to avoid
         // unnecessary temporaries.
diff --git a/src/librustc_mir/transform/instcombine.rs b/src/librustc_mir/transform/instcombine.rs
index bd237b5..eca1b59 100644
--- a/src/librustc_mir/transform/instcombine.rs
+++ b/src/librustc_mir/transform/instcombine.rs
@@ -1,7 +1,7 @@
 //! Performs various peephole optimizations.
 
 use rustc::mir::{
-    Constant, Location, Place, PlaceBase, PlaceRef, Body, BodyCache, Operand, ProjectionElem,
+    Constant, Location, Place, PlaceBase, PlaceRef, Body, BodyAndCache, Operand, ProjectionElem,
     Rvalue, Local, read_only
 };
 use rustc::mir::visit::{MutVisitor, Visitor};
@@ -14,7 +14,7 @@
 pub struct InstCombine;
 
 impl<'tcx> MirPass<'tcx> for InstCombine {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         // We only run when optimizing MIR (at any level).
         if tcx.sess.opts.debugging_opts.mir_opt_level == 0 {
             return
diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs
index df4cb76..bedf2a9 100644
--- a/src/librustc_mir/transform/mod.rs
+++ b/src/librustc_mir/transform/mod.rs
@@ -1,7 +1,7 @@
 use crate::{build, shim};
 use rustc_index::vec::IndexVec;
 use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
-use rustc::mir::{BodyCache, MirPhase, Promoted, ConstQualifs};
+use rustc::mir::{BodyAndCache, MirPhase, Promoted, ConstQualifs};
 use rustc::ty::{TyCtxt, InstanceDef, TypeFoldable};
 use rustc::ty::query::Providers;
 use rustc::ty::steal::Steal;
@@ -97,7 +97,7 @@
     tcx.arena.alloc(set)
 }
 
-fn mir_built(tcx: TyCtxt<'_>, def_id: DefId) -> &Steal<BodyCache<'_>> {
+fn mir_built(tcx: TyCtxt<'_>, def_id: DefId) -> &Steal<BodyAndCache<'_>> {
     let mir = build::mir_build(tcx, def_id);
     tcx.alloc_steal_mir(mir)
 }
@@ -144,12 +144,12 @@
         default_name::<Self>()
     }
 
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>);
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>);
 }
 
 pub fn run_passes(
     tcx: TyCtxt<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     instance: InstanceDef<'tcx>,
     promoted: Option<Promoted>,
     mir_phase: MirPhase,
@@ -220,7 +220,7 @@
     validator.qualifs_in_return_place().into()
 }
 
-fn mir_const(tcx: TyCtxt<'_>, def_id: DefId) -> &Steal<BodyCache<'_>> {
+fn mir_const(tcx: TyCtxt<'_>, def_id: DefId) -> &Steal<BodyAndCache<'_>> {
     // Unsafety check uses the raw mir, so make sure it is run
     let _ = tcx.unsafety_check_result(def_id);
 
@@ -238,7 +238,7 @@
 fn mir_validated(
     tcx: TyCtxt<'tcx>,
     def_id: DefId,
-) -> (&'tcx Steal<BodyCache<'tcx>>, &'tcx Steal<IndexVec<Promoted, BodyCache<'tcx>>>) {
+) -> (&'tcx Steal<BodyAndCache<'tcx>>, &'tcx Steal<IndexVec<Promoted, BodyAndCache<'tcx>>>) {
     // Ensure that we compute the `mir_const_qualif` for constants at
     // this point, before we steal the mir-const result.
     let _ = tcx.mir_const_qualif(def_id);
@@ -257,7 +257,7 @@
 
 fn run_optimization_passes<'tcx>(
     tcx: TyCtxt<'tcx>,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     def_id: DefId,
     promoted: Option<Promoted>,
 ) {
@@ -319,7 +319,7 @@
     ]);
 }
 
-fn optimized_mir(tcx: TyCtxt<'_>, def_id: DefId) -> &BodyCache<'_> {
+fn optimized_mir(tcx: TyCtxt<'_>, def_id: DefId) -> &BodyAndCache<'_> {
     if tcx.is_constructor(def_id) {
         // There's no reason to run all of the MIR passes on constructors when
         // we can just output the MIR we want directly. This also saves const
@@ -339,7 +339,7 @@
     tcx.arena.alloc(body)
 }
 
-fn promoted_mir(tcx: TyCtxt<'_>, def_id: DefId) -> &IndexVec<Promoted, BodyCache<'_>> {
+fn promoted_mir(tcx: TyCtxt<'_>, def_id: DefId) -> &IndexVec<Promoted, BodyAndCache<'_>> {
     if tcx.is_constructor(def_id) {
         return tcx.intern_promoted(IndexVec::new());
     }
diff --git a/src/librustc_mir/transform/no_landing_pads.rs b/src/librustc_mir/transform/no_landing_pads.rs
index 5e1d29d..d4fe72f 100644
--- a/src/librustc_mir/transform/no_landing_pads.rs
+++ b/src/librustc_mir/transform/no_landing_pads.rs
@@ -17,12 +17,12 @@
 }
 
 impl<'tcx> MirPass<'tcx> for NoLandingPads<'tcx> {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         no_landing_pads(tcx, body)
     }
 }
 
-pub fn no_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyCache<'tcx>) {
+pub fn no_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyAndCache<'tcx>) {
     if tcx.sess.no_landing_pads() {
         NoLandingPads::new(tcx).visit_body(body);
     }
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index c758ccf..4c72319 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -41,11 +41,11 @@
 /// newly created `StaticKind::Promoted`.
 #[derive(Default)]
 pub struct PromoteTemps<'tcx> {
-    pub promoted_fragments: Cell<IndexVec<Promoted, BodyCache<'tcx>>>,
+    pub promoted_fragments: Cell<IndexVec<Promoted, BodyAndCache<'tcx>>>,
 }
 
 impl<'tcx> MirPass<'tcx> for PromoteTemps<'tcx> {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         // There's not really any point in promoting errorful MIR.
         //
         // This does not include MIR that failed const-checking, which we still try to promote.
@@ -742,7 +742,7 @@
 // FIXME(eddyb) remove the differences for promotability in `static`, `const`, `const fn`.
 pub fn validate_candidates(
     tcx: TyCtxt<'tcx>,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     def_id: DefId,
     temps: &IndexVec<Local, TempState>,
     candidates: &[Candidate],
@@ -775,8 +775,8 @@
 
 struct Promoter<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    source: &'a mut BodyCache<'tcx>,
-    promoted: BodyCache<'tcx>,
+    source: &'a mut BodyAndCache<'tcx>,
+    promoted: BodyAndCache<'tcx>,
     temps: &'a mut IndexVec<Local, TempState>,
 
     /// If true, all nested temps are also kept in the
@@ -924,7 +924,7 @@
         def_id: DefId,
         candidate: Candidate,
         next_promoted_id: usize,
-    ) -> Option<BodyCache<'tcx>> {
+    ) -> Option<BodyAndCache<'tcx>> {
         let mut operand = {
             let promoted = &mut self.promoted;
             let promoted_id = Promoted::new(next_promoted_id);
@@ -1045,11 +1045,11 @@
 
 pub fn promote_candidates<'tcx>(
     def_id: DefId,
-    body: &mut BodyCache<'tcx>,
+    body: &mut BodyAndCache<'tcx>,
     tcx: TyCtxt<'tcx>,
     mut temps: IndexVec<Local, TempState>,
     candidates: Vec<Candidate>,
-) -> IndexVec<Promoted, BodyCache<'tcx>> {
+) -> IndexVec<Promoted, BodyAndCache<'tcx>> {
     // Visit candidates in reverse, in case they're nested.
     debug!("promote_candidates({:?})", candidates);
 
@@ -1081,7 +1081,7 @@
         ).collect();
 
         let promoter = Promoter {
-            promoted: BodyCache::new(Body::new(
+            promoted: BodyAndCache::new(Body::new(
                 IndexVec::new(),
                 // FIXME: maybe try to filter this to avoid blowing up
                 // memory usage?
@@ -1150,7 +1150,7 @@
 crate fn should_suggest_const_in_array_repeat_expressions_attribute<'tcx>(
     tcx: TyCtxt<'tcx>,
     mir_def_id: DefId,
-    body: ReadOnlyBodyCache<'_, 'tcx>,
+    body: ReadOnlyBodyAndCache<'_, 'tcx>,
     operand: &Operand<'tcx>,
 ) -> bool {
     let mut rpo = traversal::reverse_postorder(&body);
diff --git a/src/librustc_mir/transform/qualify_min_const_fn.rs b/src/librustc_mir/transform/qualify_min_const_fn.rs
index 3030d2e..cf2e130 100644
--- a/src/librustc_mir/transform/qualify_min_const_fn.rs
+++ b/src/librustc_mir/transform/qualify_min_const_fn.rs
@@ -79,10 +79,14 @@
 fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span, fn_def_id: DefId) -> McfResult {
     for ty in ty.walk() {
         match ty.kind {
-            ty::Ref(_, _, hir::Mutability::Mutable) => return Err((
-                span,
-                "mutable references in const fn are unstable".into(),
-            )),
+            ty::Ref(_, _, hir::Mutability::Mutable) => {
+                if !tcx.features().const_mut_refs {
+                    return Err((
+                        span,
+                        "mutable references in const fn are unstable".into(),
+                    ))
+                }
+            }
             ty::Opaque(..) => return Err((span, "`impl Trait` in const fn is unstable".into())),
             ty::FnPtr(..) => {
                 if !tcx.const_fn_is_allowed_fn_ptr(fn_def_id) {
diff --git a/src/librustc_mir/transform/remove_noop_landing_pads.rs b/src/librustc_mir/transform/remove_noop_landing_pads.rs
index c636aba..5799d0c 100644
--- a/src/librustc_mir/transform/remove_noop_landing_pads.rs
+++ b/src/librustc_mir/transform/remove_noop_landing_pads.rs
@@ -9,7 +9,7 @@
 /// code for these.
 pub struct RemoveNoopLandingPads;
 
-pub fn remove_noop_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyCache<'tcx>) {
+pub fn remove_noop_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyAndCache<'tcx>) {
     if tcx.sess.no_landing_pads() {
         return
     }
@@ -19,7 +19,7 @@
 }
 
 impl<'tcx> MirPass<'tcx> for RemoveNoopLandingPads {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         remove_noop_landing_pads(tcx, body);
     }
 }
@@ -84,7 +84,7 @@
         }
     }
 
-    fn remove_nop_landing_pads(&self, body: &mut BodyCache<'_>) {
+    fn remove_nop_landing_pads(&self, body: &mut BodyAndCache<'_>) {
         // make sure there's a single resume block
         let resume_block = {
             let patch = MirPatch::new(body);
diff --git a/src/librustc_mir/transform/rustc_peek.rs b/src/librustc_mir/transform/rustc_peek.rs
index 794ced1..2a81e97 100644
--- a/src/librustc_mir/transform/rustc_peek.rs
+++ b/src/librustc_mir/transform/rustc_peek.rs
@@ -5,7 +5,7 @@
 
 use rustc::ty::{self, TyCtxt, Ty};
 use rustc::hir::def_id::DefId;
-use rustc::mir::{self, Body, BodyCache, Location, Local};
+use rustc::mir::{self, Body, BodyAndCache, Location, Local};
 use rustc_index::bit_set::BitSet;
 use crate::transform::{MirPass, MirSource};
 
@@ -26,7 +26,7 @@
 pub struct SanityCheck;
 
 impl<'tcx> MirPass<'tcx> for SanityCheck {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let def_id = src.def_id();
         if !tcx.has_attr(def_id, sym::rustc_mir) {
             debug!("skipping rustc_peek::SanityCheck on {}", tcx.def_path_str(def_id));
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index 900752d..eef39f8 100644
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -43,7 +43,7 @@
     }
 }
 
-pub fn simplify_cfg(body: &mut BodyCache<'_>) {
+pub fn simplify_cfg(body: &mut BodyAndCache<'_>) {
     CfgSimplifier::new(body).simplify();
     remove_dead_blocks(body);
 
@@ -57,7 +57,7 @@
     }
 
     fn run_pass(
-        &self, _tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, _tcx: TyCtxt<'tcx>, _src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         debug!("SimplifyCfg({:?}) - simplifying {:?}", self.label, body);
         simplify_cfg(body);
@@ -70,7 +70,7 @@
 }
 
 impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
-    pub fn new(body: &'a mut BodyCache<'tcx>) -> Self {
+    pub fn new(body: &'a mut BodyAndCache<'tcx>) -> Self {
         let mut pred_count = IndexVec::from_elem(0u32, body.basic_blocks());
 
         // we can't use mir.predecessors() here because that counts
@@ -262,7 +262,7 @@
     }
 }
 
-pub fn remove_dead_blocks(body: &mut BodyCache<'_>) {
+pub fn remove_dead_blocks(body: &mut BodyAndCache<'_>) {
     let mut seen = BitSet::new_empty(body.basic_blocks().len());
     for (bb, _) in traversal::preorder(body) {
         seen.insert(bb.index());
@@ -296,7 +296,7 @@
 
 impl<'tcx> MirPass<'tcx> for SimplifyLocals {
     fn run_pass(
-        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>
+        &self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>
     ) {
         trace!("running SimplifyLocals on {:?}", source);
         let locals = {
diff --git a/src/librustc_mir/transform/simplify_branches.rs b/src/librustc_mir/transform/simplify_branches.rs
index c8d0f37..aa3c5b0 100644
--- a/src/librustc_mir/transform/simplify_branches.rs
+++ b/src/librustc_mir/transform/simplify_branches.rs
@@ -19,7 +19,7 @@
         Cow::Borrowed(&self.label)
     }
 
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let param_env = tcx.param_env(src.def_id());
         for block in body.basic_blocks_mut() {
             let terminator = block.terminator_mut();
diff --git a/src/librustc_mir/transform/simplify_try.rs b/src/librustc_mir/transform/simplify_try.rs
index 2235de9..752e852 100644
--- a/src/librustc_mir/transform/simplify_try.rs
+++ b/src/librustc_mir/transform/simplify_try.rs
@@ -33,7 +33,7 @@
 pub struct SimplifyArmIdentity;
 
 impl<'tcx> MirPass<'tcx> for SimplifyArmIdentity {
-    fn run_pass(&self, _: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, _: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
         for bb in basic_blocks {
             // Need 3 statements:
@@ -151,7 +151,7 @@
 pub struct SimplifyBranchSame;
 
 impl<'tcx> MirPass<'tcx> for SimplifyBranchSame {
-    fn run_pass(&self, _: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, _: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let mut did_remove_blocks = false;
         let bbs = body.basic_blocks_mut();
         for bb_idx in bbs.indices() {
diff --git a/src/librustc_mir/transform/uniform_array_move_out.rs b/src/librustc_mir/transform/uniform_array_move_out.rs
index 3fc76ef..71dd405 100644
--- a/src/librustc_mir/transform/uniform_array_move_out.rs
+++ b/src/librustc_mir/transform/uniform_array_move_out.rs
@@ -37,7 +37,7 @@
 pub struct UniformArrayMoveOut;
 
 impl<'tcx> MirPass<'tcx> for UniformArrayMoveOut {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let mut patch = MirPatch::new(body);
         let param_env = tcx.param_env(src.def_id());
         {
@@ -186,7 +186,7 @@
 }
 
 impl<'tcx> MirPass<'tcx> for RestoreSubsliceArrayMoveOut<'tcx> {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, src: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         let mut patch = MirPatch::new(body);
         let param_env = tcx.param_env(src.def_id());
         {
diff --git a/src/librustc_mir/transform/uninhabited_enum_branching.rs b/src/librustc_mir/transform/uninhabited_enum_branching.rs
index de070d7..0bf0ff2 100644
--- a/src/librustc_mir/transform/uninhabited_enum_branching.rs
+++ b/src/librustc_mir/transform/uninhabited_enum_branching.rs
@@ -2,7 +2,7 @@
 
 use crate::transform::{MirPass, MirSource};
 use rustc::mir::{
-    BasicBlock, BasicBlockData, Body, BodyCache, Local, Operand, Rvalue, StatementKind,
+    BasicBlock, BasicBlockData, Body, BodyAndCache, Local, Operand, Rvalue, StatementKind,
     TerminatorKind,
 };
 use rustc::ty::layout::{Abi, TyLayout, Variants};
@@ -29,7 +29,7 @@
     // Only bother checking blocks which terminate by switching on a local.
     if let Some(local) = get_discriminant_local(&terminator.kind) {
         let stmt_before_term = (block_data.statements.len() > 0)
-            .then_with(|| &block_data.statements[block_data.statements.len() - 1].kind);
+            .then(|| &block_data.statements[block_data.statements.len() - 1].kind);
 
         if let Some(StatementKind::Assign(box (l, Rvalue::Discriminant(place)))) = stmt_before_term
         {
@@ -59,14 +59,14 @@
             .iter_enumerated()
             .filter_map(|(idx, layout)| {
                 (layout.abi != Abi::Uninhabited)
-                    .then_with(|| ty.discriminant_for_variant(tcx, idx).unwrap().val)
+                    .then(|| ty.discriminant_for_variant(tcx, idx).unwrap().val)
             })
             .collect(),
     }
 }
 
 impl<'tcx> MirPass<'tcx> for UninhabitedEnumBranching {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyCache<'tcx>) {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
         if source.promoted.is_some() {
             return;
         }
diff --git a/src/librustc_mir/util/collect_writes.rs b/src/librustc_mir/util/collect_writes.rs
index f94bea2..4006787 100644
--- a/src/librustc_mir/util/collect_writes.rs
+++ b/src/librustc_mir/util/collect_writes.rs
@@ -1,5 +1,5 @@
 use rustc::mir::{Local, Location};
-use rustc::mir::ReadOnlyBodyCache;
+use rustc::mir::ReadOnlyBodyAndCache;
 use rustc::mir::visit::PlaceContext;
 use rustc::mir::visit::Visitor;
 
@@ -9,7 +9,7 @@
     fn find_assignments(&self, local: Local) -> Vec<Location>;
 }
 
-impl<'a, 'tcx> FindAssignments for ReadOnlyBodyCache<'a, 'tcx>{
+impl<'a, 'tcx> FindAssignments for ReadOnlyBodyAndCache<'a, 'tcx>{
     fn find_assignments(&self, local: Local) -> Vec<Location>{
             let mut visitor = FindLocalAssignmentVisitor{ needle: local, locations: vec![]};
             visitor.visit_body(*self);
diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs
index 1907e9b..cf98755 100644
--- a/src/librustc_mir/util/def_use.rs
+++ b/src/librustc_mir/util/def_use.rs
@@ -1,6 +1,8 @@
 //! Def-use analysis.
 
-use rustc::mir::{Body, BodyCache, Local, Location, PlaceElem, ReadOnlyBodyCache, VarDebugInfo};
+use rustc::mir::{
+    Body, BodyAndCache, Local, Location, PlaceElem, ReadOnlyBodyAndCache, VarDebugInfo,
+};
 use rustc::mir::visit::{PlaceContext, MutVisitor, Visitor};
 use rustc::ty::TyCtxt;
 use rustc_index::vec::IndexVec;
@@ -30,7 +32,7 @@
         }
     }
 
-    pub fn analyze(&mut self, body: ReadOnlyBodyCache<'_, '_>) {
+    pub fn analyze(&mut self, body: ReadOnlyBodyAndCache<'_, '_>) {
         self.clear();
 
         let mut finder = DefUseFinder {
@@ -55,7 +57,7 @@
     fn mutate_defs_and_uses(
         &self,
         local: Local,
-        body: &mut BodyCache<'tcx>,
+        body: &mut BodyAndCache<'tcx>,
         new_local: Local,
         tcx: TyCtxt<'tcx>,
     ) {
@@ -73,7 +75,7 @@
     // FIXME(pcwalton): this should update the def-use chains.
     pub fn replace_all_defs_and_uses_with(&self,
                                           local: Local,
-                                          body: &mut BodyCache<'tcx>,
+                                          body: &mut BodyAndCache<'tcx>,
                                           new_local: Local,
                                           tcx: TyCtxt<'tcx>) {
         self.mutate_defs_and_uses(local, body, new_local, tcx)
diff --git a/src/librustc_mir/util/graphviz.rs b/src/librustc_mir/util/graphviz.rs
index 3a7ec9f..a44d401 100644
--- a/src/librustc_mir/util/graphviz.rs
+++ b/src/librustc_mir/util/graphviz.rs
@@ -202,7 +202,7 @@
     }
 
     for var_debug_info in &body.var_debug_info {
-        write!(w, r#"debug {} => {};<br align="left"/>"#,
+        write!(w, r#"debug {} =&gt; {};<br align="left"/>"#,
                var_debug_info.name, escape(&var_debug_info.place))?;
     }
 
diff --git a/src/librustc_mir/util/liveness.rs b/src/librustc_mir/util/liveness.rs
index 3349753..68c2e16 100644
--- a/src/librustc_mir/util/liveness.rs
+++ b/src/librustc_mir/util/liveness.rs
@@ -57,7 +57,7 @@
 /// Computes which local variables are live within the given function
 /// `mir`, including drops.
 pub fn liveness_of_locals(
-    body: ReadOnlyBodyCache<'_, '_>,
+    body: ReadOnlyBodyAndCache<'_, '_>,
 ) -> LivenessResult {
     let num_live_vars = body.local_decls.len();
 
diff --git a/src/librustc_mir/util/patch.rs b/src/librustc_mir/util/patch.rs
index 47bb0b6..575b6d2 100644
--- a/src/librustc_mir/util/patch.rs
+++ b/src/librustc_mir/util/patch.rs
@@ -127,7 +127,7 @@
         self.make_nop.push(loc);
     }
 
-    pub fn apply(self, body: &mut BodyCache<'tcx>) {
+    pub fn apply(self, body: &mut BodyAndCache<'tcx>) {
         debug!("MirPatch: make nops at: {:?}", self.make_nop);
         for loc in self.make_nop {
             body.make_statement_nop(loc);
diff --git a/src/librustc_parse/config.rs b/src/librustc_parse/config.rs
index 30e056e..1e9203f 100644
--- a/src/librustc_parse/config.rs
+++ b/src/librustc_parse/config.rs
@@ -8,18 +8,19 @@
 //!
 //! [#64197]: https://github.com/rust-lang/rust/issues/64197
 
-use crate::validate_attr;
+use crate::{parse_in, validate_attr};
 use rustc_feature::Features;
 use rustc_errors::Applicability;
 use syntax::attr::HasAttrs;
 use syntax::feature_gate::{feature_err, get_features};
 use syntax::attr;
-use syntax::ast;
+use syntax::ast::{self, Attribute, AttrItem, MetaItem};
 use syntax::edition::Edition;
 use syntax::mut_visit::*;
 use syntax::ptr::P;
 use syntax::sess::ParseSess;
 use syntax::util::map_in_place::MapInPlace;
+use syntax_pos::Span;
 use syntax_pos::symbol::sym;
 
 use smallvec::SmallVec;
@@ -72,10 +73,15 @@
     }
 }
 
+const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
+const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
+    <https://doc.rust-lang.org/reference/conditional-compilation.html\
+    #the-cfg_attr-attribute>";
+
 impl<'a> StripUnconfigured<'a> {
     pub fn configure<T: HasAttrs>(&mut self, mut node: T) -> Option<T> {
         self.process_cfg_attrs(&mut node);
-        if self.in_cfg(node.attrs()) { Some(node) } else { None }
+        self.in_cfg(node.attrs()).then_some(node)
     }
 
     /// Parse and expand all `cfg_attr` attributes into a list of attributes
@@ -97,34 +103,14 @@
     /// Gives a compiler warning when the `cfg_attr` contains no attributes and
     /// is in the original source file. Gives a compiler error if the syntax of
     /// the attribute is incorrect.
-    fn process_cfg_attr(&mut self, attr: ast::Attribute) -> Vec<ast::Attribute> {
+    fn process_cfg_attr(&mut self, attr: Attribute) -> Vec<Attribute> {
         if !attr.has_name(sym::cfg_attr) {
             return vec![attr];
         }
-        if let ast::MacArgs::Empty = attr.get_normal_item().args {
-            self.sess.span_diagnostic
-                .struct_span_err(
-                    attr.span,
-                    "malformed `cfg_attr` attribute input",
-                ).span_suggestion(
-                    attr.span,
-                    "missing condition and attribute",
-                    "#[cfg_attr(condition, attribute, other_attribute, ...)]".to_owned(),
-                    Applicability::HasPlaceholders,
-                ).note("for more information, visit \
-                       <https://doc.rust-lang.org/reference/conditional-compilation.html\
-                       #the-cfg_attr-attribute>")
-                .emit();
-            return vec![];
-        }
 
-        let res = crate::parse_in_attr(self.sess, &attr, |p| p.parse_cfg_attr());
-        let (cfg_predicate, expanded_attrs) = match res {
-            Ok(result) => result,
-            Err(mut e) => {
-                e.emit();
-                return vec![];
-            }
+        let (cfg_predicate, expanded_attrs) = match self.parse_cfg_attr(&attr) {
+            None => return vec![],
+            Some(r) => r,
         };
 
         // Lint on zero attributes in source.
@@ -135,24 +121,56 @@
         // At this point we know the attribute is considered used.
         attr::mark_used(&attr);
 
-        if attr::cfg_matches(&cfg_predicate, self.sess, self.features) {
-            // We call `process_cfg_attr` recursively in case there's a
-            // `cfg_attr` inside of another `cfg_attr`. E.g.
-            //  `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
-            expanded_attrs.into_iter()
-            .flat_map(|(item, span)| self.process_cfg_attr(attr::mk_attr_from_item(
-                attr.style,
-                item,
-                span,
-            )))
-            .collect()
-        } else {
-            vec![]
+        if !attr::cfg_matches(&cfg_predicate, self.sess, self.features) {
+            return vec![];
         }
+
+        // We call `process_cfg_attr` recursively in case there's a
+        // `cfg_attr` inside of another `cfg_attr`. E.g.
+        //  `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
+        expanded_attrs
+            .into_iter()
+            .flat_map(|(item, span)| {
+                let attr = attr::mk_attr_from_item(attr.style, item, span);
+                self.process_cfg_attr(attr)
+            })
+            .collect()
+    }
+
+    fn parse_cfg_attr(&self, attr: &Attribute) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
+        match attr.get_normal_item().args {
+            ast::MacArgs::Delimited(dspan, delim, ref tts) if !tts.is_empty() => {
+                let msg = "wrong `cfg_attr` delimiters";
+                validate_attr::check_meta_bad_delim(self.sess, dspan, delim, msg);
+                match parse_in(self.sess, tts.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
+                    Ok(r) => return Some(r),
+                    Err(mut e) => e
+                        .help(&format!("the valid syntax is `{}`", CFG_ATTR_GRAMMAR_HELP))
+                        .note(CFG_ATTR_NOTE_REF)
+                        .emit(),
+                }
+            }
+            _ => self.error_malformed_cfg_attr_missing(attr.span),
+        }
+        None
+    }
+
+    fn error_malformed_cfg_attr_missing(&self, span: Span) {
+        self.sess
+            .span_diagnostic
+            .struct_span_err(span, "malformed `cfg_attr` attribute input")
+            .span_suggestion(
+                span,
+                "missing condition and attribute",
+                CFG_ATTR_GRAMMAR_HELP.to_string(),
+                Applicability::HasPlaceholders,
+            )
+            .note(CFG_ATTR_NOTE_REF)
+            .emit();
     }
 
     /// Determines if a node with the given attributes should be included in this configuration.
-    pub fn in_cfg(&self, attrs: &[ast::Attribute]) -> bool {
+    pub fn in_cfg(&self, attrs: &[Attribute]) -> bool {
         attrs.iter().all(|attr| {
             if !is_cfg(attr) {
                 return true;
@@ -199,7 +217,7 @@
     }
 
     /// Visit attributes on expression and statements (but not attributes on items in blocks).
-    fn visit_expr_attrs(&mut self, attrs: &[ast::Attribute]) {
+    fn visit_expr_attrs(&mut self, attrs: &[Attribute]) {
         // flag the offending attributes
         for attr in attrs.iter() {
             self.maybe_emit_expr_attr_err(attr);
@@ -207,7 +225,7 @@
     }
 
     /// If attributes are not allowed on expressions, emit an error for `attr`
-    pub fn maybe_emit_expr_attr_err(&self, attr: &ast::Attribute) {
+    pub fn maybe_emit_expr_attr_err(&self, attr: &Attribute) {
         if !self.features.map(|features| features.stmt_expr_attributes).unwrap_or(true) {
             let mut err = feature_err(self.sess,
                                       sym::stmt_expr_attributes,
@@ -350,7 +368,7 @@
     }
 }
 
-fn is_cfg(attr: &ast::Attribute) -> bool {
+fn is_cfg(attr: &Attribute) -> bool {
     attr.check_name(sym::cfg)
 }
 
@@ -359,8 +377,8 @@
 pub fn process_configure_mod(
     sess: &ParseSess,
     cfg_mods: bool,
-    attrs: &[ast::Attribute],
-) -> (bool, Vec<ast::Attribute>) {
+    attrs: &[Attribute],
+) -> (bool, Vec<Attribute>) {
     // Don't perform gated feature checking.
     let mut strip_unconfigured = StripUnconfigured { sess, features: None };
     let mut attrs = attrs.to_owned();
diff --git a/src/librustc_parse/lib.rs b/src/librustc_parse/lib.rs
index a222f3f..faff386 100644
--- a/src/librustc_parse/lib.rs
+++ b/src/librustc_parse/lib.rs
@@ -1,5 +1,6 @@
 //! The main parser interface.
 
+#![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 
 use syntax::ast;
@@ -270,21 +271,13 @@
 }
 
 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
-pub fn parse_in_attr<'a, T>(
+pub fn parse_in<'a, T>(
     sess: &'a ParseSess,
-    attr: &ast::Attribute,
+    tts: TokenStream,
+    name: &'static str,
     mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 ) -> PResult<'a, T> {
-    let mut parser = Parser::new(
-        sess,
-        // FIXME(#66940, Centril | petrochenkov): refactor this function so it doesn't
-        // require reconstructing and immediately re-parsing delimiters.
-        attr.get_normal_item().args.outer_tokens(),
-        None,
-        false,
-        false,
-        Some("attribute"),
-    );
+    let mut parser = Parser::new(sess, tts, None, false, false, Some(name));
     let result = f(&mut parser)?;
     if parser.token != token::Eof {
         parser.unexpected()?;
diff --git a/src/librustc_parse/parser/attr.rs b/src/librustc_parse/parser/attr.rs
index b2ae934..00fd6b8 100644
--- a/src/librustc_parse/parser/attr.rs
+++ b/src/librustc_parse/parser/attr.rs
@@ -220,7 +220,7 @@
         Ok(attrs)
     }
 
-    pub(super) fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
+    crate fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
         let lit = self.parse_lit()?;
         debug!("checking if {:?} is unusuffixed", lit);
 
@@ -238,25 +238,36 @@
 
     /// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
     pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-
         let cfg_predicate = self.parse_meta_item()?;
         self.expect(&token::Comma)?;
 
         // Presumably, the majority of the time there will only be one attr.
         let mut expanded_attrs = Vec::with_capacity(1);
-
-        while !self.check(&token::CloseDelim(token::Paren)) {
-            let lo = self.token.span.lo();
+        while self.token.kind != token::Eof {
+            let lo = self.token.span;
             let item = self.parse_attr_item()?;
-            expanded_attrs.push((item, self.prev_span.with_lo(lo)));
-            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
+            expanded_attrs.push((item, lo.to(self.prev_span)));
+            if !self.eat(&token::Comma) {
+                break;
+            }
         }
 
-        self.expect(&token::CloseDelim(token::Paren))?;
         Ok((cfg_predicate, expanded_attrs))
     }
 
+    /// Matches `COMMASEP(meta_item_inner)`.
+    crate fn parse_meta_seq_top(&mut self) -> PResult<'a, Vec<ast::NestedMetaItem>> {
+        // Presumably, the majority of the time there will only be one attr.
+        let mut nmis = Vec::with_capacity(1);
+        while self.token.kind != token::Eof {
+            nmis.push(self.parse_meta_item_inner()?);
+            if !self.eat(&token::Comma) {
+                break;
+            }
+        }
+        Ok(nmis)
+    }
+
     /// Matches the following grammar (per RFC 1559).
     ///
     ///     meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;
diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index ccf78e6..34ef12e 100644
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -1181,6 +1181,7 @@
                         attrs,
                         vis: visibility,
                         kind: ForeignItemKind::Macro(mac),
+                        tokens: None,
                     }
                 )
             }
@@ -1211,6 +1212,7 @@
             id: DUMMY_NODE_ID,
             span: lo.to(hi),
             vis,
+            tokens: None,
         })
     }
 
@@ -1228,7 +1230,8 @@
             kind: ForeignItemKind::Ty,
             id: DUMMY_NODE_ID,
             span: lo.to(hi),
-            vis
+            vis,
+            tokens: None,
         })
     }
 
@@ -1727,9 +1730,10 @@
     /// Checks if current token is one of tokens which cannot be nested like `kw::Enum`. In case
     /// it is, we try to parse the item and report error about nested types.
     fn recover_nested_adt_item(&mut self, keyword: Symbol) -> PResult<'a, bool> {
-        if self.token.is_keyword(kw::Enum) ||
+        if (self.token.is_keyword(kw::Enum) ||
             self.token.is_keyword(kw::Struct) ||
-            self.token.is_keyword(kw::Union)
+            self.token.is_keyword(kw::Union))
+           && self.look_ahead(1, |t| t.is_ident())
         {
             let kw_token = self.token.clone();
             let kw_str = pprust::token_to_string(&kw_token);
@@ -1825,6 +1829,7 @@
             id: DUMMY_NODE_ID,
             span,
             vis,
+            tokens: None,
         })
     }
 
diff --git a/src/librustc_parse/parser/path.rs b/src/librustc_parse/parser/path.rs
index 70c3458..5334fc4 100644
--- a/src/librustc_parse/parser/path.rs
+++ b/src/librustc_parse/parser/path.rs
@@ -3,7 +3,6 @@
 use rustc_errors::{PResult, Applicability, pluralize};
 use syntax::ast::{self, QSelf, Path, PathSegment, Ident, ParenthesizedArgs, AngleBracketedArgs};
 use syntax::ast::{AnonConst, GenericArg, AssocTyConstraint, AssocTyConstraintKind, BlockCheckMode};
-use syntax::ast::MacArgs;
 use syntax::ThinVec;
 use syntax::token::{self, Token};
 use syntax_pos::source_map::{Span, BytePos};
@@ -109,42 +108,6 @@
         Ok(Path { segments, span: lo.to(self.prev_span) })
     }
 
-    /// Like `parse_path`, but also supports parsing `Word` meta items into paths for
-    /// backwards-compatibility. This is used when parsing derive macro paths in `#[derive]`
-    /// attributes.
-    fn parse_path_allowing_meta(&mut self, style: PathStyle) -> PResult<'a, Path> {
-        let meta_ident = match self.token.kind {
-            token::Interpolated(ref nt) => match **nt {
-                token::NtMeta(ref item) => match item.args {
-                    MacArgs::Empty => Some(item.path.clone()),
-                    _ => None,
-                },
-                _ => None,
-            },
-            _ => None,
-        };
-        if let Some(path) = meta_ident {
-            self.bump();
-            return Ok(path);
-        }
-        self.parse_path(style)
-    }
-
-    /// Parse a list of paths inside `#[derive(path_0, ..., path_n)]`.
-    pub fn parse_derive_paths(&mut self) -> PResult<'a, Vec<Path>> {
-        self.expect(&token::OpenDelim(token::Paren))?;
-        let mut list = Vec::new();
-        while !self.eat(&token::CloseDelim(token::Paren)) {
-            let path = self.parse_path_allowing_meta(PathStyle::Mod)?;
-            list.push(path);
-            if !self.eat(&token::Comma) {
-                self.expect(&token::CloseDelim(token::Paren))?;
-                break
-            }
-        }
-        Ok(list)
-    }
-
     pub(super) fn parse_path_segments(
         &mut self,
         segments: &mut Vec<PathSegment>,
diff --git a/src/librustc_parse/validate_attr.rs b/src/librustc_parse/validate_attr.rs
index 97e9cb8..94d3fe7 100644
--- a/src/librustc_parse/validate_attr.rs
+++ b/src/librustc_parse/validate_attr.rs
@@ -1,10 +1,13 @@
 //! Meta-syntax validation logic of attributes for post-expansion.
 
+use crate::parse_in;
+
 use rustc_errors::{PResult, Applicability};
 use rustc_feature::{AttributeTemplate, BUILTIN_ATTRIBUTE_MAP};
-use syntax::ast::{self, Attribute, AttrKind, Ident, MacArgs, MetaItem, MetaItemKind};
+use syntax::ast::{self, Attribute, AttrKind, Ident, MacArgs, MacDelimiter, MetaItem, MetaItemKind};
 use syntax::attr::mk_name_value_item_str;
 use syntax::early_buffered_lints::ILL_FORMED_ATTRIBUTE_INPUT;
+use syntax::tokenstream::DelimSpan;
 use syntax::sess::ParseSess;
 use syntax_pos::{Symbol, sym};
 
@@ -27,9 +30,20 @@
 pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, MetaItem> {
     Ok(match attr.kind {
         AttrKind::Normal(ref item) => MetaItem {
-            path: item.path.clone(),
-            kind: super::parse_in_attr(sess, attr, |p| p.parse_meta_item_kind())?,
             span: attr.span,
+            path: item.path.clone(),
+            kind: match &attr.get_normal_item().args {
+                MacArgs::Empty => MetaItemKind::Word,
+                MacArgs::Eq(_, t) => {
+                    let v = parse_in(sess, t.clone(), "name value", |p| p.parse_unsuffixed_lit())?;
+                    MetaItemKind::NameValue(v)
+                }
+                MacArgs::Delimited(dspan, delim, t) => {
+                    check_meta_bad_delim(sess, *dspan, *delim, "wrong meta list delimiters");
+                    let nmis = parse_in(sess, t.clone(), "meta list", |p| p.parse_meta_seq_top())?;
+                    MetaItemKind::List(nmis)
+                }
+            }
         },
         AttrKind::DocComment(comment) => {
             mk_name_value_item_str(Ident::new(sym::doc, attr.span), comment, attr.span)
@@ -37,6 +51,24 @@
     })
 }
 
+crate fn check_meta_bad_delim(sess: &ParseSess, span: DelimSpan, delim: MacDelimiter, msg: &str) {
+    if let ast::MacDelimiter::Parenthesis = delim {
+        return;
+    }
+
+    sess.span_diagnostic
+        .struct_span_err(span.entire(), msg)
+        .multipart_suggestion(
+            "the delimiters should be `(` and `)`",
+            vec![
+                (span.open, "(".to_string()),
+                (span.close, ")".to_string()),
+            ],
+            Applicability::MachineApplicable,
+        )
+        .emit();
+}
+
 /// Checks that the given meta-item is compatible with this `AttributeTemplate`.
 fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaItemKind) -> bool {
     match meta {
diff --git a/src/librustc_resolve/diagnostics.rs b/src/librustc_resolve/diagnostics.rs
index 4dcafb6..8dd45f5 100644
--- a/src/librustc_resolve/diagnostics.rs
+++ b/src/librustc_resolve/diagnostics.rs
@@ -422,11 +422,7 @@
                 Scope::MacroUsePrelude => {
                     suggestions.extend(this.macro_use_prelude.iter().filter_map(|(name, binding)| {
                         let res = binding.res();
-                        if filter_fn(res) {
-                            Some(TypoSuggestion::from_res(*name, res))
-                        } else {
-                            None
-                        }
+                        filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
                     }));
                 }
                 Scope::BuiltinAttrs => {
@@ -440,11 +436,7 @@
                 Scope::ExternPrelude => {
                     suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
                         let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
-                        if filter_fn(res) {
-                            Some(TypoSuggestion::from_res(ident.name, res))
-                        } else {
-                            None
-                        }
+                        filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
                     }));
                 }
                 Scope::ToolPrelude => {
@@ -467,11 +459,7 @@
                     suggestions.extend(
                         primitive_types.iter().flat_map(|(name, prim_ty)| {
                             let res = Res::PrimTy(*prim_ty);
-                            if filter_fn(res) {
-                                Some(TypoSuggestion::from_res(*name, res))
-                            } else {
-                                None
-                            }
+                            filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
                         })
                     )
                 }
diff --git a/src/librustc_resolve/late.rs b/src/librustc_resolve/late.rs
index 666c482..4f95d6f 100644
--- a/src/librustc_resolve/late.rs
+++ b/src/librustc_resolve/late.rs
@@ -496,11 +496,7 @@
                 GenericParamKind::Lifetime { .. } => None,
                 GenericParamKind::Type { ref default, .. } => {
                     found_default |= default.is_some();
-                    if found_default {
-                        Some((Ident::with_dummy_span(param.ident.name), Res::Err))
-                    } else {
-                        None
-                    }
+                    found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
                 }
             }));
 
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index be36e02..31f59e4 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -9,6 +9,7 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 #![feature(label_break_value)]
 #![feature(nll)]
diff --git a/src/librustc_session/session.rs b/src/librustc_session/session.rs
index 9369c17..150d207 100644
--- a/src/librustc_session/session.rs
+++ b/src/librustc_session/session.rs
@@ -752,11 +752,7 @@
     }
 
     pub fn incr_comp_session_dir_opt(&self) -> Option<cell::Ref<'_, PathBuf>> {
-        if self.opts.incremental.is_some() {
-            Some(self.incr_comp_session_dir())
-        } else {
-            None
-        }
+        self.opts.incremental.as_ref().map(|_| self.incr_comp_session_dir())
     }
 
     pub fn print_perf_stats(&self) {
@@ -1079,8 +1075,9 @@
                     None
                 }
             }
-        }
-        else { None };
+        } else {
+            None
+        };
 
     let host_triple = TargetTriple::from_triple(config::host_triple());
     let host = Target::search(&host_triple).unwrap_or_else(|e|
diff --git a/src/librustc_target/abi/call/aarch64.rs b/src/librustc_target/abi/call/aarch64.rs
index 45fe475..06c001e 100644
--- a/src/librustc_target/abi/call/aarch64.rs
+++ b/src/librustc_target/abi/call/aarch64.rs
@@ -20,14 +20,7 @@
             RegKind::Vector => size.bits() == 64 || size.bits() == 128
         };
 
-        if valid_unit {
-            Some(Uniform {
-                unit,
-                total: size
-            })
-        } else {
-            None
-        }
+        valid_unit.then_some(Uniform { unit, total: size })
     })
 }
 
diff --git a/src/librustc_target/abi/call/arm.rs b/src/librustc_target/abi/call/arm.rs
index ff929f3..36971c1 100644
--- a/src/librustc_target/abi/call/arm.rs
+++ b/src/librustc_target/abi/call/arm.rs
@@ -21,14 +21,7 @@
             RegKind::Vector => size.bits() == 64 || size.bits() == 128
         };
 
-        if valid_unit {
-            Some(Uniform {
-                unit,
-                total: size
-            })
-        } else {
-            None
-        }
+        valid_unit.then_some(Uniform { unit, total: size })
     })
 }
 
diff --git a/src/librustc_target/abi/call/mod.rs b/src/librustc_target/abi/call/mod.rs
index 6f53577..5119464 100644
--- a/src/librustc_target/abi/call/mod.rs
+++ b/src/librustc_target/abi/call/mod.rs
@@ -416,11 +416,7 @@
         // i686-pc-windows-msvc, it results in wrong stack offsets.
         // attrs.pointee_align = Some(self.layout.align.abi);
 
-        let extra_attrs = if self.layout.is_unsized() {
-            Some(ArgAttributes::new())
-        } else {
-            None
-        };
+        let extra_attrs = self.layout.is_unsized().then_some(ArgAttributes::new());
 
         self.mode = PassMode::Indirect(attrs, extra_attrs);
     }
diff --git a/src/librustc_target/abi/call/powerpc64.rs b/src/librustc_target/abi/call/powerpc64.rs
index f967a83..fe45948 100644
--- a/src/librustc_target/abi/call/powerpc64.rs
+++ b/src/librustc_target/abi/call/powerpc64.rs
@@ -32,14 +32,7 @@
             RegKind::Vector => arg.layout.size.bits() == 128
         };
 
-        if valid_unit {
-            Some(Uniform {
-                unit,
-                total: arg.layout.size
-            })
-        } else {
-            None
-        }
+        valid_unit.then_some(Uniform { unit, total: arg.layout.size })
     })
 }
 
diff --git a/src/librustc_target/abi/call/sparc64.rs b/src/librustc_target/abi/call/sparc64.rs
index fe2c427..32be7b8 100644
--- a/src/librustc_target/abi/call/sparc64.rs
+++ b/src/librustc_target/abi/call/sparc64.rs
@@ -20,14 +20,7 @@
             RegKind::Vector => arg.layout.size.bits() == 128
         };
 
-        if valid_unit {
-            Some(Uniform {
-                unit,
-                total: arg.layout.size
-            })
-        } else {
-            None
-        }
+        valid_unit.then_some(Uniform { unit, total: arg.layout.size })
     })
 }
 
diff --git a/src/librustc_target/lib.rs b/src/librustc_target/lib.rs
index 5582eaf..6a1498e 100644
--- a/src/librustc_target/lib.rs
+++ b/src/librustc_target/lib.rs
@@ -10,6 +10,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
 #![feature(box_syntax)]
+#![feature(bool_to_option)]
 #![feature(nll)]
 #![feature(slice_patterns)]
 
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index 901a219..253fc55 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -1284,6 +1284,10 @@
                     augment_error(&mut err);
                 }
 
+                if let Some(expr) = expression {
+                    fcx.emit_coerce_suggestions(&mut err, expr, found, expected);
+                }
+
                 // Error possibly reported in `check_assign` so avoid emitting error again.
                 err.emit_unless(expression.filter(|e| fcx.is_assign_to_bool(e, expected))
                     .is_some());
diff --git a/src/librustc_typeck/check/demand.rs b/src/librustc_typeck/check/demand.rs
index 32df6c4..16a55d2 100644
--- a/src/librustc_typeck/check/demand.rs
+++ b/src/librustc_typeck/check/demand.rs
@@ -15,6 +15,22 @@
 use super::method::probe;
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+
+    pub fn emit_coerce_suggestions(
+        &self,
+        err: &mut DiagnosticBuilder<'_>,
+        expr: &hir::Expr,
+        expr_ty: Ty<'tcx>,
+        expected: Ty<'tcx>
+    ) {
+        self.annotate_expected_due_to_let_ty(err, expr);
+        self.suggest_compatible_variants(err, expr, expected, expr_ty);
+        self.suggest_ref_or_into(err, expr, expected, expr_ty);
+        self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty);
+        self.suggest_missing_await(err, expr, expected, expr_ty);
+    }
+
+
     // Requires that the two types unify, and prints an error message if
     // they don't.
     pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
@@ -137,11 +153,7 @@
             return (expected, None)
         }
 
-        self.annotate_expected_due_to_let_ty(&mut err, expr);
-        self.suggest_compatible_variants(&mut err, expr, expected, expr_ty);
-        self.suggest_ref_or_into(&mut err, expr, expected, expr_ty);
-        self.suggest_boxing_when_appropriate(&mut err, expr, expected, expr_ty);
-        self.suggest_missing_await(&mut err, expr, expected, expr_ty);
+        self.emit_coerce_suggestions(&mut err, expr, expr_ty, expected);
 
         (expected, Some(err))
     }
diff --git a/src/librustc_typeck/check/intrinsic.rs b/src/librustc_typeck/check/intrinsic.rs
index 9f034e6..cec8311 100644
--- a/src/librustc_typeck/check/intrinsic.rs
+++ b/src/librustc_typeck/check/intrinsic.rs
@@ -1,7 +1,6 @@
 //! Type-checking for the rust-intrinsic and platform-intrinsic
 //! intrinsics that the compiler exposes.
 
-use rustc::middle::lang_items::PanicLocationLangItem;
 use rustc::traits::{ObligationCause, ObligationCauseCode};
 use rustc::ty::{self, TyCtxt, Ty};
 use rustc::ty::subst::Subst;
@@ -148,15 +147,7 @@
                  ], tcx.types.usize)
             }
             "rustc_peek" => (1, vec![param(0)], param(0)),
-            "caller_location" => (
-                0,
-                vec![],
-                tcx.mk_imm_ref(
-                    tcx.lifetimes.re_static,
-                    tcx.type_of(tcx.require_lang_item(PanicLocationLangItem, None))
-                        .subst(tcx, tcx.mk_substs([tcx.lifetimes.re_static.into()].iter())),
-                ),
-            ),
+            "caller_location" => (0, vec![], tcx.caller_location_ty()),
             "panic_if_uninhabited" => (1, Vec::new(), tcx.mk_unit()),
             "init" => (1, Vec::new(), param(0)),
             "uninit" => (1, Vec::new(), param(0)),
@@ -336,6 +327,7 @@
                 (1, vec![param(0), param(0)], param(0)),
             "fadd_fast" | "fsub_fast" | "fmul_fast" | "fdiv_fast" | "frem_fast" =>
                 (1, vec![param(0), param(0)], param(0)),
+            "float_to_int_approx_unchecked" => (2, vec![ param(0) ], param(1)),
 
             "assume" => (0, vec![tcx.types.bool], tcx.mk_unit()),
             "likely" => (0, vec![tcx.types.bool], tcx.types.bool),
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
index 9717190..9923081 100644
--- a/src/librustc_typeck/check/method/probe.rs
+++ b/src/librustc_typeck/check/method/probe.rs
@@ -1105,11 +1105,7 @@
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
                 pick.autoref = Some(mutbl);
-                pick.unsize = if step.unsize {
-                    Some(self_ty)
-                } else {
-                    None
-                };
+                pick.unsize = step.unsize.then_some(self_ty);
                 pick
             })
         })
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index c7a0190..a956aba 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4584,8 +4584,6 @@
             pointing_at_return_type = self.suggest_missing_return_type(
                 err, &fn_decl, expected, found, can_suggest);
         }
-        self.suggest_ref_or_into(err, expr, expected, found);
-        self.suggest_boxing_when_appropriate(err, expr, expected, found);
         pointing_at_return_type
     }
 
@@ -4957,7 +4955,9 @@
                     ty: expected,
                 }));
                 let obligation = traits::Obligation::new(self.misc(sp), self.param_env, predicate);
+                debug!("suggest_missing_await: trying obligation {:?}", obligation);
                 if self.infcx.predicate_may_hold(&obligation) {
+                    debug!("suggest_missing_await: obligation held: {:?}", obligation);
                     if let Ok(code) = self.sess().source_map().span_to_snippet(sp) {
                         err.span_suggestion(
                             sp,
@@ -4965,7 +4965,11 @@
                             format!("{}.await", code),
                             Applicability::MaybeIncorrect,
                         );
+                    } else {
+                        debug!("suggest_missing_await: no snippet for {:?}", sp);
                     }
+                } else {
+                    debug!("suggest_missing_await: obligation did not hold: {:?}", obligation)
                 }
             }
         }
diff --git a/src/librustc_typeck/check/upvar.rs b/src/librustc_typeck/check/upvar.rs
index 3002459..c5a6c07 100644
--- a/src/librustc_typeck/check/upvar.rs
+++ b/src/librustc_typeck/check/upvar.rs
@@ -114,11 +114,7 @@
         };
 
         let infer_kind = if let UpvarSubsts::Closure(closure_substs) = substs {
-            if self.closure_kind(closure_def_id, closure_substs).is_none() {
-                Some(closure_substs)
-            } else {
-                None
-            }
+            self.closure_kind(closure_def_id, closure_substs).is_none().then_some(closure_substs)
         } else {
             None
         };
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 6d6e768..b982979 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -2616,7 +2616,7 @@
                     tcx.sess,
                     attr.span,
                     E0737,
-                    "Rust ABI is required to use `#[track_caller]`"
+                    "`#[track_caller]` requires Rust ABI"
                 ).emit();
             }
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index c606fea..6a6294b 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -59,6 +59,7 @@
 
 #![allow(non_camel_case_types)]
 
+#![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]
diff --git a/src/librustdoc/clean/cfg.rs b/src/librustdoc/clean/cfg.rs
index 078948c..fb2cce3 100644
--- a/src/librustdoc/clean/cfg.rs
+++ b/src/librustdoc/clean/cfg.rs
@@ -209,6 +209,9 @@
 
 impl ops::BitAndAssign for Cfg {
     fn bitand_assign(&mut self, other: Cfg) {
+        if *self == other {
+            return;
+        }
         match (self, other) {
             (&mut Cfg::False, _) | (_, Cfg::True) => {},
             (s, Cfg::False) => *s = Cfg::False,
@@ -238,6 +241,9 @@
 
 impl ops::BitOrAssign for Cfg {
     fn bitor_assign(&mut self, other: Cfg) {
+        if *self == other {
+            return;
+        }
         match (self, other) {
             (&mut Cfg::True, _) | (_, Cfg::False) => {},
             (s, Cfg::True) => *s = Cfg::True,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 4d8d004..327be40 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -5,12 +5,12 @@
 
 pub mod inline;
 pub mod cfg;
-mod simplify;
 mod auto_trait;
 mod blanket_impl;
+mod simplify;
+pub mod types;
 
 use rustc_index::vec::{IndexVec, Idx};
-use rustc_target::spec::abi::Abi;
 use rustc_typeck::hir_ty_to_ty;
 use rustc::infer::region_constraints::{RegionConstraintData, Constraint};
 use rustc::middle::resolve_lifetime as rl;
@@ -24,46 +24,33 @@
 use rustc::ty::subst::{InternalSubsts, SubstsRef, GenericArgKind};
 use rustc::ty::{self, DefIdTree, TyCtxt, Region, RegionVid, Ty, AdtKind};
 use rustc::ty::fold::TypeFolder;
-use rustc::ty::layout::VariantIdx;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
-use syntax::ast::{self, Attribute, AttrStyle, AttrKind, Ident};
+use syntax::ast::{self, Ident};
 use syntax::attr;
-use syntax::util::comments;
-use syntax::source_map::DUMMY_SP;
 use syntax_pos::symbol::{Symbol, kw, sym};
 use syntax_pos::hygiene::MacroKind;
-use syntax_pos::{self, Pos, FileName};
+use syntax_pos::{self, Pos};
 
 use std::collections::hash_map::Entry;
-use std::fmt;
-use std::hash::{Hash, Hasher};
+use std::hash::Hash;
 use std::default::Default;
-use std::{mem, slice, vec};
-use std::num::NonZeroU32;
-use std::iter::FromIterator;
+use std::{mem, vec};
 use std::rc::Rc;
-use std::cell::RefCell;
-use std::sync::Arc;
 use std::u32;
 
 use crate::core::{self, DocContext, ImplTraitParam};
 use crate::doctree;
-use crate::html::render::{cache, ExternalLocation};
-use crate::html::item_type::ItemType;
 
-
-use self::cfg::Cfg;
 use self::auto_trait::AutoTraitFinder;
 use self::blanket_impl::BlanketImplFinder;
 
-pub use self::Type::*;
-pub use self::Mutability::*;
-pub use self::ItemEnum::*;
-pub use self::SelfTy::*;
-pub use self::FunctionRetTy::*;
-pub use self::Visibility::{Public, Inherited};
-
-thread_local!(pub static MAX_DEF_ID: RefCell<FxHashMap<CrateNum, DefId>> = Default::default());
+pub use self::types::*;
+pub use self::types::Type::*;
+pub use self::types::Mutability::*;
+pub use self::types::ItemEnum::*;
+pub use self::types::SelfTy::*;
+pub use self::types::FunctionRetTy::*;
+pub use self::types::Visibility::{Public, Inherited};
 
 const FN_OUTPUT_NAME: &'static str = "Output";
 
@@ -122,21 +109,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Crate {
-    pub name: String,
-    pub version: Option<String>,
-    pub src: FileName,
-    pub module: Option<Item>,
-    pub externs: Vec<(CrateNum, ExternalCrate)>,
-    pub primitives: Vec<(DefId, PrimitiveType, Attributes)>,
-    // These are later on moved into `CACHEKEY`, leaving the map empty.
-    // Only here so that they can be filtered through the rustdoc passes.
-    pub external_traits: Rc<RefCell<FxHashMap<DefId, Trait>>>,
-    pub masked_crates: FxHashSet<CrateNum>,
-    pub collapsed: bool,
-}
-
 pub fn krate(mut cx: &mut DocContext<'_>) -> Crate {
     use crate::visit_lib::LibEmbargoVisitor;
 
@@ -222,15 +194,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct ExternalCrate {
-    pub name: String,
-    pub src: FileName,
-    pub attrs: Attributes,
-    pub primitives: Vec<(DefId, PrimitiveType, Attributes)>,
-    pub keywords: Vec<(DefId, String, Attributes)>,
-}
-
 impl Clean<ExternalCrate> for CrateNum {
     fn clean(&self, cx: &DocContext<'_>) -> ExternalCrate {
         let root = DefId { krate: *self, index: CRATE_DEF_INDEX };
@@ -351,237 +314,6 @@
     }
 }
 
-/// Anything with a source location and set of attributes and, optionally, a
-/// name. That is, anything that can be documented. This doesn't correspond
-/// directly to the AST's concept of an item; it's a strict superset.
-#[derive(Clone)]
-pub struct Item {
-    /// Stringified span
-    pub source: Span,
-    /// Not everything has a name. E.g., impls
-    pub name: Option<String>,
-    pub attrs: Attributes,
-    pub inner: ItemEnum,
-    pub visibility: Visibility,
-    pub def_id: DefId,
-    pub stability: Option<Stability>,
-    pub deprecation: Option<Deprecation>,
-}
-
-impl fmt::Debug for Item {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-
-        let fake = MAX_DEF_ID.with(|m| m.borrow().get(&self.def_id.krate)
-                                   .map(|id| self.def_id >= *id).unwrap_or(false));
-        let def_id: &dyn fmt::Debug = if fake { &"**FAKE**" } else { &self.def_id };
-
-        fmt.debug_struct("Item")
-            .field("source", &self.source)
-            .field("name", &self.name)
-            .field("attrs", &self.attrs)
-            .field("inner", &self.inner)
-            .field("visibility", &self.visibility)
-            .field("def_id", def_id)
-            .field("stability", &self.stability)
-            .field("deprecation", &self.deprecation)
-            .finish()
-    }
-}
-
-impl Item {
-    /// Finds the `doc` attribute as a NameValue and returns the corresponding
-    /// value found.
-    pub fn doc_value(&self) -> Option<&str> {
-        self.attrs.doc_value()
-    }
-    /// Finds all `doc` attributes as NameValues and returns their corresponding values, joined
-    /// with newlines.
-    pub fn collapsed_doc_value(&self) -> Option<String> {
-        self.attrs.collapsed_doc_value()
-    }
-
-    pub fn links(&self) -> Vec<(String, String)> {
-        self.attrs.links(&self.def_id.krate)
-    }
-
-    pub fn is_crate(&self) -> bool {
-        match self.inner {
-            StrippedItem(box ModuleItem(Module { is_crate: true, ..})) |
-            ModuleItem(Module { is_crate: true, ..}) => true,
-            _ => false,
-        }
-    }
-    pub fn is_mod(&self) -> bool {
-        self.type_() == ItemType::Module
-    }
-    pub fn is_trait(&self) -> bool {
-        self.type_() == ItemType::Trait
-    }
-    pub fn is_struct(&self) -> bool {
-        self.type_() == ItemType::Struct
-    }
-    pub fn is_enum(&self) -> bool {
-        self.type_() == ItemType::Enum
-    }
-    pub fn is_variant(&self) -> bool {
-        self.type_() == ItemType::Variant
-    }
-    pub fn is_associated_type(&self) -> bool {
-        self.type_() == ItemType::AssocType
-    }
-    pub fn is_associated_const(&self) -> bool {
-        self.type_() == ItemType::AssocConst
-    }
-    pub fn is_method(&self) -> bool {
-        self.type_() == ItemType::Method
-    }
-    pub fn is_ty_method(&self) -> bool {
-        self.type_() == ItemType::TyMethod
-    }
-    pub fn is_typedef(&self) -> bool {
-        self.type_() == ItemType::Typedef
-    }
-    pub fn is_primitive(&self) -> bool {
-        self.type_() == ItemType::Primitive
-    }
-    pub fn is_union(&self) -> bool {
-        self.type_() == ItemType::Union
-    }
-    pub fn is_import(&self) -> bool {
-        self.type_() == ItemType::Import
-    }
-    pub fn is_extern_crate(&self) -> bool {
-        self.type_() == ItemType::ExternCrate
-    }
-    pub fn is_keyword(&self) -> bool {
-        self.type_() == ItemType::Keyword
-    }
-
-    pub fn is_stripped(&self) -> bool {
-        match self.inner { StrippedItem(..) => true, _ => false }
-    }
-    pub fn has_stripped_fields(&self) -> Option<bool> {
-        match self.inner {
-            StructItem(ref _struct) => Some(_struct.fields_stripped),
-            UnionItem(ref union) => Some(union.fields_stripped),
-            VariantItem(Variant { kind: VariantKind::Struct(ref vstruct)} ) => {
-                Some(vstruct.fields_stripped)
-            },
-            _ => None,
-        }
-    }
-
-    pub fn stability_class(&self) -> Option<String> {
-        self.stability.as_ref().and_then(|ref s| {
-            let mut classes = Vec::with_capacity(2);
-
-            if s.level == stability::Unstable {
-                classes.push("unstable");
-            }
-
-            if s.deprecation.is_some() {
-                classes.push("deprecated");
-            }
-
-            if classes.len() != 0 {
-                Some(classes.join(" "))
-            } else {
-                None
-            }
-        })
-    }
-
-    pub fn stable_since(&self) -> Option<&str> {
-        self.stability.as_ref().map(|s| &s.since[..])
-    }
-
-    pub fn is_non_exhaustive(&self) -> bool {
-        self.attrs.other_attrs.iter()
-            .any(|a| a.check_name(sym::non_exhaustive))
-    }
-
-    /// Returns a documentation-level item type from the item.
-    pub fn type_(&self) -> ItemType {
-        ItemType::from(self)
-    }
-
-    /// Returns the info in the item's `#[deprecated]` or `#[rustc_deprecated]` attributes.
-    ///
-    /// If the item is not deprecated, returns `None`.
-    pub fn deprecation(&self) -> Option<&Deprecation> {
-        self.deprecation
-            .as_ref()
-            .or_else(|| self.stability.as_ref().and_then(|s| s.deprecation.as_ref()))
-    }
-    pub fn is_default(&self) -> bool {
-        match self.inner {
-            ItemEnum::MethodItem(ref meth) => {
-                if let Some(defaultness) = meth.defaultness {
-                    defaultness.has_value() && !defaultness.is_final()
-                } else {
-                    false
-                }
-            }
-            _ => false,
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub enum ItemEnum {
-    ExternCrateItem(String, Option<String>),
-    ImportItem(Import),
-    StructItem(Struct),
-    UnionItem(Union),
-    EnumItem(Enum),
-    FunctionItem(Function),
-    ModuleItem(Module),
-    TypedefItem(Typedef, bool /* is associated type */),
-    OpaqueTyItem(OpaqueTy, bool /* is associated type */),
-    StaticItem(Static),
-    ConstantItem(Constant),
-    TraitItem(Trait),
-    TraitAliasItem(TraitAlias),
-    ImplItem(Impl),
-    /// A method signature only. Used for required methods in traits (ie,
-    /// non-default-methods).
-    TyMethodItem(TyMethod),
-    /// A method with a body.
-    MethodItem(Method),
-    StructFieldItem(Type),
-    VariantItem(Variant),
-    /// `fn`s from an extern block
-    ForeignFunctionItem(Function),
-    /// `static`s from an extern block
-    ForeignStaticItem(Static),
-    /// `type`s from an extern block
-    ForeignTypeItem,
-    MacroItem(Macro),
-    ProcMacroItem(ProcMacro),
-    PrimitiveItem(PrimitiveType),
-    AssocConstItem(Type, Option<String>),
-    AssocTypeItem(Vec<GenericBound>, Option<Type>),
-    /// An item that has been stripped by a rustdoc pass
-    StrippedItem(Box<ItemEnum>),
-    KeywordItem(String),
-}
-
-impl ItemEnum {
-    pub fn is_associated(&self) -> bool {
-        match *self {
-            ItemEnum::TypedefItem(_, _) |
-            ItemEnum::AssocTypeItem(_, _) => true,
-            _ => false,
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct Module {
-    pub items: Vec<Item>,
-    pub is_crate: bool,
-}
-
 impl Clean<Item> for doctree::Module<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let name = if self.name.is_some() {
@@ -645,465 +377,12 @@
     }
 }
 
-pub struct ListAttributesIter<'a> {
-    attrs: slice::Iter<'a, ast::Attribute>,
-    current_list: vec::IntoIter<ast::NestedMetaItem>,
-    name: Symbol,
-}
-
-impl<'a> Iterator for ListAttributesIter<'a> {
-    type Item = ast::NestedMetaItem;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if let Some(nested) = self.current_list.next() {
-            return Some(nested);
-        }
-
-        for attr in &mut self.attrs {
-            if let Some(list) = attr.meta_item_list() {
-                if attr.check_name(self.name) {
-                    self.current_list = list.into_iter();
-                    if let Some(nested) = self.current_list.next() {
-                        return Some(nested);
-                    }
-                }
-            }
-        }
-
-        None
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        let lower = self.current_list.len();
-        (lower, None)
-    }
-}
-
-pub trait AttributesExt {
-    /// Finds an attribute as List and returns the list of attributes nested inside.
-    fn lists(&self, name: Symbol) -> ListAttributesIter<'_>;
-}
-
-impl AttributesExt for [ast::Attribute] {
-    fn lists(&self, name: Symbol) -> ListAttributesIter<'_> {
-        ListAttributesIter {
-            attrs: self.iter(),
-            current_list: Vec::new().into_iter(),
-            name,
-        }
-    }
-}
-
-pub trait NestedAttributesExt {
-    /// Returns `true` if the attribute list contains a specific `Word`
-    fn has_word(self, word: Symbol) -> bool;
-}
-
-impl<I: IntoIterator<Item=ast::NestedMetaItem>> NestedAttributesExt for I {
-    fn has_word(self, word: Symbol) -> bool {
-        self.into_iter().any(|attr| attr.is_word() && attr.check_name(word))
-    }
-}
-
-/// A portion of documentation, extracted from a `#[doc]` attribute.
-///
-/// Each variant contains the line number within the complete doc-comment where the fragment
-/// starts, as well as the Span where the corresponding doc comment or attribute is located.
-///
-/// Included files are kept separate from inline doc comments so that proper line-number
-/// information can be given when a doctest fails. Sugared doc comments and "raw" doc comments are
-/// kept separate because of issue #42760.
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum DocFragment {
-    /// A doc fragment created from a `///` or `//!` doc comment.
-    SugaredDoc(usize, syntax_pos::Span, String),
-    /// A doc fragment created from a "raw" `#[doc=""]` attribute.
-    RawDoc(usize, syntax_pos::Span, String),
-    /// A doc fragment created from a `#[doc(include="filename")]` attribute. Contains both the
-    /// given filename and the file contents.
-    Include(usize, syntax_pos::Span, String, String),
-}
-
-impl DocFragment {
-    pub fn as_str(&self) -> &str {
-        match *self {
-            DocFragment::SugaredDoc(_, _, ref s) => &s[..],
-            DocFragment::RawDoc(_, _, ref s) => &s[..],
-            DocFragment::Include(_, _, _, ref s) => &s[..],
-        }
-    }
-
-    pub fn span(&self) -> syntax_pos::Span {
-        match *self {
-            DocFragment::SugaredDoc(_, span, _) |
-                DocFragment::RawDoc(_, span, _) |
-                DocFragment::Include(_, span, _, _) => span,
-        }
-    }
-}
-
-impl<'a> FromIterator<&'a DocFragment> for String {
-    fn from_iter<T>(iter: T) -> Self
-    where
-        T: IntoIterator<Item = &'a DocFragment>
-    {
-        iter.into_iter().fold(String::new(), |mut acc, frag| {
-            if !acc.is_empty() {
-                acc.push('\n');
-            }
-            match *frag {
-                DocFragment::SugaredDoc(_, _, ref docs)
-                    | DocFragment::RawDoc(_, _, ref docs)
-                    | DocFragment::Include(_, _, _, ref docs) =>
-                    acc.push_str(docs),
-            }
-
-            acc
-        })
-    }
-}
-
-#[derive(Clone, Debug, Default)]
-pub struct Attributes {
-    pub doc_strings: Vec<DocFragment>,
-    pub other_attrs: Vec<ast::Attribute>,
-    pub cfg: Option<Arc<Cfg>>,
-    pub span: Option<syntax_pos::Span>,
-    /// map from Rust paths to resolved defs and potential URL fragments
-    pub links: Vec<(String, Option<DefId>, Option<String>)>,
-    pub inner_docs: bool,
-}
-
-impl Attributes {
-    /// Extracts the content from an attribute `#[doc(cfg(content))]`.
-    fn extract_cfg(mi: &ast::MetaItem) -> Option<&ast::MetaItem> {
-        use syntax::ast::NestedMetaItem::MetaItem;
-
-        if let ast::MetaItemKind::List(ref nmis) = mi.kind {
-            if nmis.len() == 1 {
-                if let MetaItem(ref cfg_mi) = nmis[0] {
-                    if cfg_mi.check_name(sym::cfg) {
-                        if let ast::MetaItemKind::List(ref cfg_nmis) = cfg_mi.kind {
-                            if cfg_nmis.len() == 1 {
-                                if let MetaItem(ref content_mi) = cfg_nmis[0] {
-                                    return Some(content_mi);
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-        }
-
-        None
-    }
-
-    /// Reads a `MetaItem` from within an attribute, looks for whether it is a
-    /// `#[doc(include="file")]`, and returns the filename and contents of the file as loaded from
-    /// its expansion.
-    fn extract_include(mi: &ast::MetaItem)
-        -> Option<(String, String)>
-    {
-        mi.meta_item_list().and_then(|list| {
-            for meta in list {
-                if meta.check_name(sym::include) {
-                    // the actual compiled `#[doc(include="filename")]` gets expanded to
-                    // `#[doc(include(file="filename", contents="file contents")]` so we need to
-                    // look for that instead
-                    return meta.meta_item_list().and_then(|list| {
-                        let mut filename: Option<String> = None;
-                        let mut contents: Option<String> = None;
-
-                        for it in list {
-                            if it.check_name(sym::file) {
-                                if let Some(name) = it.value_str() {
-                                    filename = Some(name.to_string());
-                                }
-                            } else if it.check_name(sym::contents) {
-                                if let Some(docs) = it.value_str() {
-                                    contents = Some(docs.to_string());
-                                }
-                            }
-                        }
-
-                        if let (Some(filename), Some(contents)) = (filename, contents) {
-                            Some((filename, contents))
-                        } else {
-                            None
-                        }
-                    });
-                }
-            }
-
-            None
-        })
-    }
-
-    pub fn has_doc_flag(&self, flag: Symbol) -> bool {
-        for attr in &self.other_attrs {
-            if !attr.check_name(sym::doc) { continue; }
-
-            if let Some(items) = attr.meta_item_list() {
-                if items.iter().filter_map(|i| i.meta_item()).any(|it| it.check_name(flag)) {
-                    return true;
-                }
-            }
-        }
-
-        false
-    }
-
-    pub fn from_ast(diagnostic: &::errors::Handler,
-                    attrs: &[ast::Attribute]) -> Attributes {
-        let mut doc_strings = vec![];
-        let mut sp = None;
-        let mut cfg = Cfg::True;
-        let mut doc_line = 0;
-
-        /// If `attr` is a doc comment, strips the leading and (if present)
-        /// trailing comments symbols, e.g. `///`, `/**`, and `*/`. Otherwise,
-        /// returns `attr` unchanged.
-        pub fn with_doc_comment_markers_stripped<T>(
-            attr: &Attribute,
-            f: impl FnOnce(&Attribute) -> T
-        ) -> T {
-            match attr.kind {
-                AttrKind::Normal(_) => {
-                    f(attr)
-                }
-                AttrKind::DocComment(comment) => {
-                    let comment =
-                        Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str()));
-                    f(&Attribute {
-                        kind: AttrKind::DocComment(comment),
-                        id: attr.id,
-                        style: attr.style,
-                        span: attr.span,
-                    })
-                }
-            }
-        }
-
-        let other_attrs = attrs.iter().filter_map(|attr| {
-            with_doc_comment_markers_stripped(attr, |attr| {
-                if attr.check_name(sym::doc) {
-                    if let Some(mi) = attr.meta() {
-                        if let Some(value) = mi.value_str() {
-                            // Extracted #[doc = "..."]
-                            let value = value.to_string();
-                            let line = doc_line;
-                            doc_line += value.lines().count();
-
-                            if attr.is_doc_comment() {
-                                doc_strings.push(DocFragment::SugaredDoc(line, attr.span, value));
-                            } else {
-                                doc_strings.push(DocFragment::RawDoc(line, attr.span, value));
-                            }
-
-                            if sp.is_none() {
-                                sp = Some(attr.span);
-                            }
-                            return None;
-                        } else if let Some(cfg_mi) = Attributes::extract_cfg(&mi) {
-                            // Extracted #[doc(cfg(...))]
-                            match Cfg::parse(cfg_mi) {
-                                Ok(new_cfg) => cfg &= new_cfg,
-                                Err(e) => diagnostic.span_err(e.span, e.msg),
-                            }
-                            return None;
-                        } else if let Some((filename, contents)) = Attributes::extract_include(&mi)
-                        {
-                            let line = doc_line;
-                            doc_line += contents.lines().count();
-                            doc_strings.push(DocFragment::Include(line,
-                                                                  attr.span,
-                                                                  filename,
-                                                                  contents));
-                        }
-                    }
-                }
-                Some(attr.clone())
-            })
-        }).collect();
-
-        // treat #[target_feature(enable = "feat")] attributes as if they were
-        // #[doc(cfg(target_feature = "feat"))] attributes as well
-        for attr in attrs.lists(sym::target_feature) {
-            if attr.check_name(sym::enable) {
-                if let Some(feat) = attr.value_str() {
-                    let meta = attr::mk_name_value_item_str(
-                        Ident::with_dummy_span(sym::target_feature), feat, DUMMY_SP
-                    );
-                    if let Ok(feat_cfg) = Cfg::parse(&meta) {
-                        cfg &= feat_cfg;
-                    }
-                }
-            }
-        }
-
-        let inner_docs = attrs.iter()
-                              .filter(|a| a.check_name(sym::doc))
-                              .next()
-                              .map_or(true, |a| a.style == AttrStyle::Inner);
-
-        Attributes {
-            doc_strings,
-            other_attrs,
-            cfg: if cfg == Cfg::True { None } else { Some(Arc::new(cfg)) },
-            span: sp,
-            links: vec![],
-            inner_docs,
-        }
-    }
-
-    /// Finds the `doc` attribute as a NameValue and returns the corresponding
-    /// value found.
-    pub fn doc_value(&self) -> Option<&str> {
-        self.doc_strings.first().map(|s| s.as_str())
-    }
-
-    /// Finds all `doc` attributes as NameValues and returns their corresponding values, joined
-    /// with newlines.
-    pub fn collapsed_doc_value(&self) -> Option<String> {
-        if !self.doc_strings.is_empty() {
-            Some(self.doc_strings.iter().collect())
-        } else {
-            None
-        }
-    }
-
-    /// Gets links as a vector
-    ///
-    /// Cache must be populated before call
-    pub fn links(&self, krate: &CrateNum) -> Vec<(String, String)> {
-        use crate::html::format::href;
-
-        self.links.iter().filter_map(|&(ref s, did, ref fragment)| {
-            match did {
-                Some(did) => {
-                    if let Some((mut href, ..)) = href(did) {
-                        if let Some(ref fragment) = *fragment {
-                            href.push_str("#");
-                            href.push_str(fragment);
-                        }
-                        Some((s.clone(), href))
-                    } else {
-                        None
-                    }
-                }
-                None => {
-                    if let Some(ref fragment) = *fragment {
-                        let cache = cache();
-                        let url = match cache.extern_locations.get(krate) {
-                            Some(&(_, ref src, ExternalLocation::Local)) =>
-                                src.to_str().expect("invalid file path"),
-                            Some(&(_, _, ExternalLocation::Remote(ref s))) => s,
-                            Some(&(_, _, ExternalLocation::Unknown)) | None =>
-                                "https://doc.rust-lang.org/nightly",
-                        };
-                        // This is a primitive so the url is done "by hand".
-                        let tail = fragment.find('#').unwrap_or_else(|| fragment.len());
-                        Some((s.clone(),
-                              format!("{}{}std/primitive.{}.html{}",
-                                      url,
-                                      if !url.ends_with('/') { "/" } else { "" },
-                                      &fragment[..tail],
-                                      &fragment[tail..])))
-                    } else {
-                        panic!("This isn't a primitive?!");
-                    }
-                }
-            }
-        }).collect()
-    }
-}
-
-impl PartialEq for Attributes {
-    fn eq(&self, rhs: &Self) -> bool {
-        self.doc_strings == rhs.doc_strings &&
-        self.cfg == rhs.cfg &&
-        self.span == rhs.span &&
-        self.links == rhs.links &&
-        self.other_attrs.iter().map(|attr| attr.id).eq(rhs.other_attrs.iter().map(|attr| attr.id))
-    }
-}
-
-impl Eq for Attributes {}
-
-impl Hash for Attributes {
-    fn hash<H: Hasher>(&self, hasher: &mut H) {
-        self.doc_strings.hash(hasher);
-        self.cfg.hash(hasher);
-        self.span.hash(hasher);
-        self.links.hash(hasher);
-        for attr in &self.other_attrs {
-            attr.id.hash(hasher);
-        }
-    }
-}
-
-impl AttributesExt for Attributes {
-    fn lists(&self, name: Symbol) -> ListAttributesIter<'_> {
-        self.other_attrs.lists(name)
-    }
-}
-
 impl Clean<Attributes> for [ast::Attribute] {
     fn clean(&self, cx: &DocContext<'_>) -> Attributes {
         Attributes::from_ast(cx.sess().diagnostic(), self)
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum GenericBound {
-    TraitBound(PolyTrait, hir::TraitBoundModifier),
-    Outlives(Lifetime),
-}
-
-impl GenericBound {
-    fn maybe_sized(cx: &DocContext<'_>) -> GenericBound {
-        let did = cx.tcx.require_lang_item(lang_items::SizedTraitLangItem, None);
-        let empty = cx.tcx.intern_substs(&[]);
-        let path = external_path(cx, cx.tcx.item_name(did),
-            Some(did), false, vec![], empty);
-        inline::record_extern_fqn(cx, did, TypeKind::Trait);
-        GenericBound::TraitBound(PolyTrait {
-            trait_: ResolvedPath {
-                path,
-                param_names: None,
-                did,
-                is_generic: false,
-            },
-            generic_params: Vec::new(),
-        }, hir::TraitBoundModifier::Maybe)
-    }
-
-    fn is_sized_bound(&self, cx: &DocContext<'_>) -> bool {
-        use rustc::hir::TraitBoundModifier as TBM;
-        if let GenericBound::TraitBound(PolyTrait { ref trait_, .. }, TBM::None) = *self {
-            if trait_.def_id() == cx.tcx.lang_items().sized_trait() {
-                return true;
-            }
-        }
-        false
-    }
-
-    fn get_poly_trait(&self) -> Option<PolyTrait> {
-        if let GenericBound::TraitBound(ref p, _) = *self {
-            return Some(p.clone())
-        }
-        None
-    }
-
-    fn get_trait_type(&self) -> Option<Type> {
-        if let GenericBound::TraitBound(PolyTrait { ref trait_, .. }, _) = *self {
-            Some(trait_.clone())
-        } else {
-            None
-        }
-    }
-}
-
 impl Clean<GenericBound> for hir::GenericBound {
     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
         match *self {
@@ -1237,21 +516,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct Lifetime(String);
-
-impl Lifetime {
-    pub fn get_ref<'a>(&'a self) -> &'a str {
-        let Lifetime(ref s) = *self;
-        let s: &'a str = s;
-        s
-    }
-
-    pub fn statik() -> Lifetime {
-        Lifetime("'static".to_string())
-    }
-}
-
 impl Clean<Lifetime> for hir::Lifetime {
     fn clean(&self, cx: &DocContext<'_>) -> Lifetime {
         if self.hir_id != hir::DUMMY_HIR_ID {
@@ -1332,23 +596,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub enum WherePredicate {
-    BoundPredicate { ty: Type, bounds: Vec<GenericBound> },
-    RegionPredicate { lifetime: Lifetime, bounds: Vec<GenericBound> },
-    EqPredicate { lhs: Type, rhs: Type },
-}
-
-impl WherePredicate {
-    pub fn get_bounds(&self) -> Option<&[GenericBound]> {
-        match *self {
-            WherePredicate::BoundPredicate { ref bounds, .. } => Some(bounds),
-            WherePredicate::RegionPredicate { ref bounds, .. } => Some(bounds),
-            _ => None,
-        }
-    }
-}
-
 impl Clean<WherePredicate> for hir::WherePredicate {
     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
         match *self {
@@ -1470,73 +717,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum GenericParamDefKind {
-    Lifetime,
-    Type {
-        did: DefId,
-        bounds: Vec<GenericBound>,
-        default: Option<Type>,
-        synthetic: Option<hir::SyntheticTyParamKind>,
-    },
-    Const {
-        did: DefId,
-        ty: Type,
-    },
-}
-
-impl GenericParamDefKind {
-    pub fn is_type(&self) -> bool {
-        match *self {
-            GenericParamDefKind::Type { .. } => true,
-            _ => false,
-        }
-    }
-
-    // FIXME(eddyb) this either returns the default of a type parameter, or the
-    // type of a `const` parameter. It seems that the intention is to *visit*
-    // any embedded types, but `get_type` seems to be the wrong name for that.
-    pub fn get_type(&self) -> Option<Type> {
-        match self {
-            GenericParamDefKind::Type { default, .. } => default.clone(),
-            GenericParamDefKind::Const { ty, .. } => Some(ty.clone()),
-            GenericParamDefKind::Lifetime => None,
-        }
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct GenericParamDef {
-    pub name: String,
-
-    pub kind: GenericParamDefKind,
-}
-
-impl GenericParamDef {
-    pub fn is_synthetic_type_param(&self) -> bool {
-        match self.kind {
-            GenericParamDefKind::Lifetime |
-            GenericParamDefKind::Const { .. } => false,
-            GenericParamDefKind::Type { ref synthetic, .. } => synthetic.is_some(),
-        }
-    }
-
-    pub fn is_type(&self) -> bool {
-        self.kind.is_type()
-    }
-
-    pub fn get_type(&self) -> Option<Type> {
-        self.kind.get_type()
-    }
-
-    pub fn get_bounds(&self) -> Option<&[GenericBound]> {
-        match self.kind {
-            GenericParamDefKind::Type { ref bounds, .. } => Some(bounds),
-            _ => None,
-        }
-    }
-}
-
 impl Clean<GenericParamDef> for ty::GenericParamDef {
     fn clean(&self, cx: &DocContext<'_>) -> GenericParamDef {
         let (name, kind) = match self.kind {
@@ -1614,13 +794,6 @@
     }
 }
 
-// maybe use a Generic enum and use Vec<Generic>?
-#[derive(Clone, Debug, Default)]
-pub struct Generics {
-    pub params: Vec<GenericParamDef>,
-    pub where_predicates: Vec<WherePredicate>,
-}
-
 impl Clean<Generics> for hir::Generics {
     fn clean(&self, cx: &DocContext<'_>) -> Generics {
         // Synthetic type-parameters are inserted after normal ones.
@@ -1975,16 +1148,6 @@
     (all_types.into_iter().collect(), ret_types)
 }
 
-#[derive(Clone, Debug)]
-pub struct Method {
-    pub generics: Generics,
-    pub decl: FnDecl,
-    pub header: hir::FnHeader,
-    pub defaultness: Option<hir::Defaultness>,
-    pub all_types: Vec<Type>,
-    pub ret_types: Vec<Type>,
-}
-
 impl<'a> Clean<Method> for (&'a hir::FnSig, &'a hir::Generics, hir::BodyId,
                             Option<hir::Defaultness>) {
     fn clean(&self, cx: &DocContext<'_>) -> Method {
@@ -2003,24 +1166,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct TyMethod {
-    pub header: hir::FnHeader,
-    pub decl: FnDecl,
-    pub generics: Generics,
-    pub all_types: Vec<Type>,
-    pub ret_types: Vec<Type>,
-}
-
-#[derive(Clone, Debug)]
-pub struct Function {
-    pub decl: FnDecl,
-    pub generics: Generics,
-    pub header: hir::FnHeader,
-    pub all_types: Vec<Type>,
-    pub ret_types: Vec<Type>,
-}
-
 impl Clean<Item> for doctree::Function<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let (generics, decl) = enter_impl_trait(cx, || {
@@ -2053,49 +1198,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct FnDecl {
-    pub inputs: Arguments,
-    pub output: FunctionRetTy,
-    pub c_variadic: bool,
-    pub attrs: Attributes,
-}
-
-impl FnDecl {
-    pub fn self_type(&self) -> Option<SelfTy> {
-        self.inputs.values.get(0).and_then(|v| v.to_self())
-    }
-
-    /// Returns the sugared return type for an async function.
-    ///
-    /// For example, if the return type is `impl std::future::Future<Output = i32>`, this function
-    /// will return `i32`.
-    ///
-    /// # Panics
-    ///
-    /// This function will panic if the return type does not match the expected sugaring for async
-    /// functions.
-    pub fn sugared_async_return_type(&self) -> FunctionRetTy {
-        match &self.output {
-            FunctionRetTy::Return(Type::ImplTrait(bounds)) => {
-                match &bounds[0] {
-                    GenericBound::TraitBound(PolyTrait { trait_, .. }, ..) => {
-                        let bindings = trait_.bindings().unwrap();
-                        FunctionRetTy::Return(bindings[0].ty().clone())
-                    }
-                    _ => panic!("unexpected desugaring of async function"),
-                }
-            }
-            _ => panic!("unexpected desugaring of async function"),
-        }
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct Arguments {
-    pub values: Vec<Argument>,
-}
-
 impl<'a> Clean<Arguments> for (&'a [hir::Ty], &'a [ast::Ident]) {
     fn clean(&self, cx: &DocContext<'_>) -> Arguments {
         Arguments {
@@ -2167,42 +1269,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct Argument {
-    pub type_: Type,
-    pub name: String,
-}
-
-#[derive(Clone, PartialEq, Debug)]
-pub enum SelfTy {
-    SelfValue,
-    SelfBorrowed(Option<Lifetime>, Mutability),
-    SelfExplicit(Type),
-}
-
-impl Argument {
-    pub fn to_self(&self) -> Option<SelfTy> {
-        if self.name != "self" {
-            return None;
-        }
-        if self.type_.is_self_type() {
-            return Some(SelfValue);
-        }
-        match self.type_ {
-            BorrowedRef{ref lifetime, mutability, ref type_} if type_.is_self_type() => {
-                Some(SelfBorrowed(lifetime.clone(), mutability))
-            }
-            _ => Some(SelfExplicit(self.type_.clone()))
-        }
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum FunctionRetTy {
-    Return(Type),
-    DefaultReturn,
-}
-
 impl Clean<FunctionRetTy> for hir::FunctionRetTy {
     fn clean(&self, cx: &DocContext<'_>) -> FunctionRetTy {
         match *self {
@@ -2212,26 +1278,6 @@
     }
 }
 
-impl GetDefId for FunctionRetTy {
-    fn def_id(&self) -> Option<DefId> {
-        match *self {
-            Return(ref ty) => ty.def_id(),
-            DefaultReturn => None,
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct Trait {
-    pub auto: bool,
-    pub unsafety: hir::Unsafety,
-    pub items: Vec<Item>,
-    pub generics: Generics,
-    pub bounds: Vec<GenericBound>,
-    pub is_spotlight: bool,
-    pub is_auto: bool,
-}
-
 impl Clean<Item> for doctree::Trait<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let attrs = self.attrs.clean(cx);
@@ -2257,12 +1303,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct TraitAlias {
-    pub generics: Generics,
-    pub bounds: Vec<GenericBound>,
-}
-
 impl Clean<Item> for doctree::TraitAlias<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let attrs = self.attrs.clean(cx);
@@ -2541,321 +1581,6 @@
     }
 }
 
-/// A trait reference, which may have higher ranked lifetimes.
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct PolyTrait {
-    pub trait_: Type,
-    pub generic_params: Vec<GenericParamDef>,
-}
-
-/// A representation of a type suitable for hyperlinking purposes. Ideally, one can get the original
-/// type out of the AST/`TyCtxt` given one of these, if more information is needed. Most
-/// importantly, it does not preserve mutability or boxes.
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum Type {
-    /// Structs/enums/traits (most that would be an `hir::TyKind::Path`).
-    ResolvedPath {
-        path: Path,
-        param_names: Option<Vec<GenericBound>>,
-        did: DefId,
-        /// `true` if is a `T::Name` path for associated types.
-        is_generic: bool,
-    },
-    /// For parameterized types, so the consumer of the JSON don't go
-    /// looking for types which don't exist anywhere.
-    Generic(String),
-    /// Primitives are the fixed-size numeric types (plus int/usize/float), char,
-    /// arrays, slices, and tuples.
-    Primitive(PrimitiveType),
-    /// `extern "ABI" fn`
-    BareFunction(Box<BareFunctionDecl>),
-    Tuple(Vec<Type>),
-    Slice(Box<Type>),
-    Array(Box<Type>, String),
-    Never,
-    RawPointer(Mutability, Box<Type>),
-    BorrowedRef {
-        lifetime: Option<Lifetime>,
-        mutability: Mutability,
-        type_: Box<Type>,
-    },
-
-    // `<Type as Trait>::Name`
-    QPath {
-        name: String,
-        self_type: Box<Type>,
-        trait_: Box<Type>
-    },
-
-    // `_`
-    Infer,
-
-    // `impl TraitA + TraitB + ...`
-    ImplTrait(Vec<GenericBound>),
-}
-
-#[derive(Clone, PartialEq, Eq, Hash, Copy, Debug)]
-pub enum PrimitiveType {
-    Isize, I8, I16, I32, I64, I128,
-    Usize, U8, U16, U32, U64, U128,
-    F32, F64,
-    Char,
-    Bool,
-    Str,
-    Slice,
-    Array,
-    Tuple,
-    Unit,
-    RawPointer,
-    Reference,
-    Fn,
-    Never,
-}
-
-#[derive(Clone, Copy, Debug)]
-pub enum TypeKind {
-    Enum,
-    Function,
-    Module,
-    Const,
-    Static,
-    Struct,
-    Union,
-    Trait,
-    Typedef,
-    Foreign,
-    Macro,
-    Attr,
-    Derive,
-    TraitAlias,
-}
-
-pub trait GetDefId {
-    fn def_id(&self) -> Option<DefId>;
-}
-
-impl<T: GetDefId> GetDefId for Option<T> {
-    fn def_id(&self) -> Option<DefId> {
-        self.as_ref().and_then(|d| d.def_id())
-    }
-}
-
-impl Type {
-    pub fn primitive_type(&self) -> Option<PrimitiveType> {
-        match *self {
-            Primitive(p) | BorrowedRef { type_: box Primitive(p), ..} => Some(p),
-            Slice(..) | BorrowedRef { type_: box Slice(..), .. } => Some(PrimitiveType::Slice),
-            Array(..) | BorrowedRef { type_: box Array(..), .. } => Some(PrimitiveType::Array),
-            Tuple(ref tys) => if tys.is_empty() {
-                Some(PrimitiveType::Unit)
-            } else {
-                Some(PrimitiveType::Tuple)
-            },
-            RawPointer(..) => Some(PrimitiveType::RawPointer),
-            BorrowedRef { type_: box Generic(..), .. } => Some(PrimitiveType::Reference),
-            BareFunction(..) => Some(PrimitiveType::Fn),
-            Never => Some(PrimitiveType::Never),
-            _ => None,
-        }
-    }
-
-    pub fn is_generic(&self) -> bool {
-        match *self {
-            ResolvedPath { is_generic, .. } => is_generic,
-            _ => false,
-        }
-    }
-
-    pub fn is_self_type(&self) -> bool {
-        match *self {
-            Generic(ref name) => name == "Self",
-            _ => false
-        }
-    }
-
-    pub fn generics(&self) -> Option<Vec<Type>> {
-        match *self {
-            ResolvedPath { ref path, .. } => {
-                path.segments.last().and_then(|seg| {
-                    if let GenericArgs::AngleBracketed { ref args, .. } = seg.args {
-                        Some(args.iter().filter_map(|arg| match arg {
-                            GenericArg::Type(ty) => Some(ty.clone()),
-                            _ => None,
-                        }).collect())
-                    } else {
-                        None
-                    }
-                })
-            }
-            _ => None,
-        }
-    }
-
-    pub fn bindings(&self) -> Option<&[TypeBinding]> {
-        match *self {
-            ResolvedPath { ref path, .. } => {
-                path.segments.last().and_then(|seg| {
-                    if let GenericArgs::AngleBracketed { ref bindings, .. } = seg.args {
-                        Some(&**bindings)
-                    } else {
-                        None
-                    }
-                })
-            }
-            _ => None
-        }
-    }
-
-    pub fn is_full_generic(&self) -> bool {
-        match *self {
-            Type::Generic(_) => true,
-            _ => false,
-        }
-    }
-
-    pub fn projection(&self) -> Option<(&Type, DefId, &str)> {
-        let (self_, trait_, name) = match self {
-            QPath { ref self_type, ref trait_, ref name } => {
-                (self_type, trait_, name)
-            }
-            _ => return None,
-        };
-        let trait_did = match **trait_ {
-            ResolvedPath { did, .. } => did,
-            _ => return None,
-        };
-        Some((&self_, trait_did, name))
-    }
-
-}
-
-impl GetDefId for Type {
-    fn def_id(&self) -> Option<DefId> {
-        match *self {
-            ResolvedPath { did, .. } => Some(did),
-            Primitive(p) => crate::html::render::cache().primitive_locations.get(&p).cloned(),
-            BorrowedRef { type_: box Generic(..), .. } =>
-                Primitive(PrimitiveType::Reference).def_id(),
-            BorrowedRef { ref type_, .. } => type_.def_id(),
-            Tuple(ref tys) => if tys.is_empty() {
-                Primitive(PrimitiveType::Unit).def_id()
-            } else {
-                Primitive(PrimitiveType::Tuple).def_id()
-            },
-            BareFunction(..) => Primitive(PrimitiveType::Fn).def_id(),
-            Never => Primitive(PrimitiveType::Never).def_id(),
-            Slice(..) => Primitive(PrimitiveType::Slice).def_id(),
-            Array(..) => Primitive(PrimitiveType::Array).def_id(),
-            RawPointer(..) => Primitive(PrimitiveType::RawPointer).def_id(),
-            QPath { ref self_type, .. } => self_type.def_id(),
-            _ => None,
-        }
-    }
-}
-
-impl PrimitiveType {
-    fn from_str(s: &str) -> Option<PrimitiveType> {
-        match s {
-            "isize" => Some(PrimitiveType::Isize),
-            "i8" => Some(PrimitiveType::I8),
-            "i16" => Some(PrimitiveType::I16),
-            "i32" => Some(PrimitiveType::I32),
-            "i64" => Some(PrimitiveType::I64),
-            "i128" => Some(PrimitiveType::I128),
-            "usize" => Some(PrimitiveType::Usize),
-            "u8" => Some(PrimitiveType::U8),
-            "u16" => Some(PrimitiveType::U16),
-            "u32" => Some(PrimitiveType::U32),
-            "u64" => Some(PrimitiveType::U64),
-            "u128" => Some(PrimitiveType::U128),
-            "bool" => Some(PrimitiveType::Bool),
-            "char" => Some(PrimitiveType::Char),
-            "str" => Some(PrimitiveType::Str),
-            "f32" => Some(PrimitiveType::F32),
-            "f64" => Some(PrimitiveType::F64),
-            "array" => Some(PrimitiveType::Array),
-            "slice" => Some(PrimitiveType::Slice),
-            "tuple" => Some(PrimitiveType::Tuple),
-            "unit" => Some(PrimitiveType::Unit),
-            "pointer" => Some(PrimitiveType::RawPointer),
-            "reference" => Some(PrimitiveType::Reference),
-            "fn" => Some(PrimitiveType::Fn),
-            "never" => Some(PrimitiveType::Never),
-            _ => None,
-        }
-    }
-
-    pub fn as_str(&self) -> &'static str {
-        use self::PrimitiveType::*;
-        match *self {
-            Isize => "isize",
-            I8 => "i8",
-            I16 => "i16",
-            I32 => "i32",
-            I64 => "i64",
-            I128 => "i128",
-            Usize => "usize",
-            U8 => "u8",
-            U16 => "u16",
-            U32 => "u32",
-            U64 => "u64",
-            U128 => "u128",
-            F32 => "f32",
-            F64 => "f64",
-            Str => "str",
-            Bool => "bool",
-            Char => "char",
-            Array => "array",
-            Slice => "slice",
-            Tuple => "tuple",
-            Unit => "unit",
-            RawPointer => "pointer",
-            Reference => "reference",
-            Fn => "fn",
-            Never => "never",
-        }
-    }
-
-    pub fn to_url_str(&self) -> &'static str {
-        self.as_str()
-    }
-}
-
-impl From<ast::IntTy> for PrimitiveType {
-    fn from(int_ty: ast::IntTy) -> PrimitiveType {
-        match int_ty {
-            ast::IntTy::Isize => PrimitiveType::Isize,
-            ast::IntTy::I8 => PrimitiveType::I8,
-            ast::IntTy::I16 => PrimitiveType::I16,
-            ast::IntTy::I32 => PrimitiveType::I32,
-            ast::IntTy::I64 => PrimitiveType::I64,
-            ast::IntTy::I128 => PrimitiveType::I128,
-        }
-    }
-}
-
-impl From<ast::UintTy> for PrimitiveType {
-    fn from(uint_ty: ast::UintTy) -> PrimitiveType {
-        match uint_ty {
-            ast::UintTy::Usize => PrimitiveType::Usize,
-            ast::UintTy::U8 => PrimitiveType::U8,
-            ast::UintTy::U16 => PrimitiveType::U16,
-            ast::UintTy::U32 => PrimitiveType::U32,
-            ast::UintTy::U64 => PrimitiveType::U64,
-            ast::UintTy::U128 => PrimitiveType::U128,
-        }
-    }
-}
-
-impl From<ast::FloatTy> for PrimitiveType {
-    fn from(float_ty: ast::FloatTy) -> PrimitiveType {
-        match float_ty {
-            ast::FloatTy::F32 => PrimitiveType::F32,
-            ast::FloatTy::F64 => PrimitiveType::F64,
-        }
-    }
-}
-
 impl Clean<Type> for hir::Ty {
     fn clean(&self, cx: &DocContext<'_>) -> Type {
         use rustc::hir::*;
@@ -3310,14 +2035,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub enum Visibility {
-    Public,
-    Inherited,
-    Crate,
-    Restricted(DefId, Path),
-}
-
 impl Clean<Visibility> for hir::Visibility {
     fn clean(&self, cx: &DocContext<'_>) -> Visibility {
         match self.node {
@@ -3339,22 +2056,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Struct {
-    pub struct_type: doctree::StructType,
-    pub generics: Generics,
-    pub fields: Vec<Item>,
-    pub fields_stripped: bool,
-}
-
-#[derive(Clone, Debug)]
-pub struct Union {
-    pub struct_type: doctree::StructType,
-    pub generics: Generics,
-    pub fields: Vec<Item>,
-    pub fields_stripped: bool,
-}
-
 impl Clean<Item> for doctree::Struct<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3395,16 +2096,6 @@
     }
 }
 
-/// This is a more limited form of the standard Struct, different in that
-/// it lacks the things most items have (name, id, parameterization). Found
-/// only as a variant in an enum.
-#[derive(Clone, Debug)]
-pub struct VariantStruct {
-    pub struct_type: doctree::StructType,
-    pub fields: Vec<Item>,
-    pub fields_stripped: bool,
-}
-
 impl Clean<VariantStruct> for ::rustc::hir::VariantData {
     fn clean(&self, cx: &DocContext<'_>) -> VariantStruct {
         VariantStruct {
@@ -3415,13 +2106,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Enum {
-    pub variants: IndexVec<VariantIdx, Item>,
-    pub generics: Generics,
-    pub variants_stripped: bool,
-}
-
 impl Clean<Item> for doctree::Enum<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3441,11 +2125,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Variant {
-    pub kind: VariantKind,
-}
-
 impl Clean<Item> for doctree::Variant<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3504,13 +2183,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub enum VariantKind {
-    CLike,
-    Tuple(Vec<Type>),
-    Struct(VariantStruct),
-}
-
 impl Clean<VariantKind> for hir::VariantData {
     fn clean(&self, cx: &DocContext<'_>) -> VariantKind {
         match self {
@@ -3522,31 +2194,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Span {
-    pub filename: FileName,
-    pub loline: usize,
-    pub locol: usize,
-    pub hiline: usize,
-    pub hicol: usize,
-    pub original: syntax_pos::Span,
-}
-
-impl Span {
-    pub fn empty() -> Span {
-        Span {
-            filename: FileName::Anon(0),
-            loline: 0, locol: 0,
-            hiline: 0, hicol: 0,
-            original: syntax_pos::DUMMY_SP,
-        }
-    }
-
-    pub fn span(&self) -> syntax_pos::Span {
-        self.original
-    }
-}
-
 impl Clean<Span> for syntax_pos::Span {
     fn clean(&self, cx: &DocContext<'_>) -> Span {
         if self.is_dummy() {
@@ -3568,19 +2215,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct Path {
-    pub global: bool,
-    pub res: Res,
-    pub segments: Vec<PathSegment>,
-}
-
-impl Path {
-    pub fn last_name(&self) -> &str {
-        self.segments.last().expect("segments were empty").name.as_str()
-    }
-}
-
 impl Clean<Path> for hir::Path {
     fn clean(&self, cx: &DocContext<'_>) -> Path {
         Path {
@@ -3591,25 +2225,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum GenericArg {
-    Lifetime(Lifetime),
-    Type(Type),
-    Const(Constant),
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum GenericArgs {
-    AngleBracketed {
-        args: Vec<GenericArg>,
-        bindings: Vec<TypeBinding>,
-    },
-    Parenthesized {
-        inputs: Vec<Type>,
-        output: Option<Type>,
-    }
-}
-
 impl Clean<GenericArgs> for hir::GenericArgs {
     fn clean(&self, cx: &DocContext<'_>) -> GenericArgs {
         if self.parenthesized {
@@ -3638,12 +2253,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct PathSegment {
-    pub name: String,
-    pub args: GenericArgs,
-}
-
 impl Clean<PathSegment> for hir::PathSegment {
     fn clean(&self, cx: &DocContext<'_>) -> PathSegment {
         PathSegment {
@@ -3727,12 +2336,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Typedef {
-    pub type_: Type,
-    pub generics: Generics,
-}
-
 impl Clean<Item> for doctree::Typedef<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3751,12 +2354,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct OpaqueTy {
-    pub bounds: Vec<GenericBound>,
-    pub generics: Generics,
-}
-
 impl Clean<Item> for doctree::OpaqueTy<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3775,14 +2372,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct BareFunctionDecl {
-    pub unsafety: hir::Unsafety,
-    pub generic_params: Vec<GenericParamDef>,
-    pub decl: FnDecl,
-    pub abi: Abi,
-}
-
 impl Clean<BareFunctionDecl> for hir::BareFnTy {
     fn clean(&self, cx: &DocContext<'_>) -> BareFunctionDecl {
         let (generic_params, decl) = enter_impl_trait(cx, || {
@@ -3797,16 +2386,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Static {
-    pub type_: Type,
-    pub mutability: Mutability,
-    /// It's useful to have the value of a static documented, but I have no
-    /// desire to represent expressions (that'd basically be all of the AST,
-    /// which is huge!). So, have a string.
-    pub expr: String,
-}
-
 impl Clean<Item> for doctree::Static<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         debug!("cleaning static {}: {:?}", self.name.clean(cx), self);
@@ -3827,12 +2406,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Hash, Debug)]
-pub struct Constant {
-    pub type_: Type,
-    pub expr: String,
-}
-
 impl Clean<Item> for doctree::Constant<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -3851,12 +2424,6 @@
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Copy, Hash)]
-pub enum Mutability {
-    Mutable,
-    Immutable,
-}
-
 impl Clean<Mutability> for hir::Mutability {
     fn clean(&self, _: &DocContext<'_>) -> Mutability {
         match self {
@@ -3866,12 +2433,6 @@
     }
 }
 
-#[derive(Clone, PartialEq, Debug)]
-pub enum ImplPolarity {
-    Positive,
-    Negative,
-}
-
 impl Clean<ImplPolarity> for ty::ImplPolarity {
     fn clean(&self, _: &DocContext<'_>) -> ImplPolarity {
         match self {
@@ -3883,19 +2444,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Impl {
-    pub unsafety: hir::Unsafety,
-    pub generics: Generics,
-    pub provided_trait_methods: FxHashSet<String>,
-    pub trait_: Option<Type>,
-    pub for_: Type,
-    pub items: Vec<Item>,
-    pub polarity: Option<ImplPolarity>,
-    pub synthetic: bool,
-    pub blanket_impl: Option<Type>,
-}
-
 pub fn get_auto_trait_and_blanket_impls(
     cx: &DocContext<'tcx>,
     ty: Ty<'tcx>,
@@ -4115,20 +2663,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub enum Import {
-    // use source as str;
-    Simple(String, ImportSource),
-    // use source::*;
-    Glob(ImportSource)
-}
-
-#[derive(Clone, Debug)]
-pub struct ImportSource {
-    pub path: Path,
-    pub did: Option<DefId>,
-}
-
 impl Clean<Item> for doctree::ForeignItem<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let inner = match self.kind {
@@ -4340,12 +2874,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Macro {
-    pub source: String,
-    pub imported_from: Option<String>,
-}
-
 impl Clean<Item> for doctree::Macro<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let name = self.name.clean(cx);
@@ -4369,12 +2897,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct ProcMacro {
-    pub kind: MacroKind,
-    pub helpers: Vec<String>,
-}
-
 impl Clean<Item> for doctree::ProcMacro<'_> {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
@@ -4393,22 +2915,6 @@
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct Stability {
-    pub level: stability::StabilityLevel,
-    pub feature: Option<String>,
-    pub since: String,
-    pub deprecation: Option<Deprecation>,
-    pub unstable_reason: Option<String>,
-    pub issue: Option<NonZeroU32>,
-}
-
-#[derive(Clone, Debug)]
-pub struct Deprecation {
-    pub since: Option<String>,
-    pub note: Option<String>,
-}
-
 impl Clean<Stability> for attr::Stability {
     fn clean(&self, _: &DocContext<'_>) -> Stability {
         Stability {
@@ -4451,33 +2957,6 @@
     }
 }
 
-/// An type binding on an associated type (e.g., `A = Bar` in `Foo<A = Bar>` or
-/// `A: Send + Sync` in `Foo<A: Send + Sync>`).
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub struct TypeBinding {
-    pub name: String,
-    pub kind: TypeBindingKind,
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum TypeBindingKind {
-    Equality {
-        ty: Type,
-    },
-    Constraint {
-        bounds: Vec<GenericBound>,
-    },
-}
-
-impl TypeBinding {
-    pub fn ty(&self) -> &Type {
-        match self.kind {
-            TypeBindingKind::Equality { ref ty } => ty,
-            _ => panic!("expected equality type binding for parenthesized generic args"),
-        }
-    }
-}
-
 impl Clean<TypeBinding> for hir::TypeBinding {
     fn clean(&self, cx: &DocContext<'_>) -> TypeBinding {
         TypeBinding {
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
new file mode 100644
index 0000000..bd3f2a3
--- /dev/null
+++ b/src/librustdoc/clean/types.rs
@@ -0,0 +1,1545 @@
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::default::Default;
+use std::{slice, vec};
+use std::num::NonZeroU32;
+use std::iter::FromIterator;
+use std::rc::Rc;
+use std::cell::RefCell;
+use std::sync::Arc;
+
+use rustc::middle::lang_items;
+use rustc::middle::stability;
+use rustc::hir;
+use rustc::hir::def::Res;
+use rustc::hir::def_id::{CrateNum, DefId};
+use rustc::ty::layout::VariantIdx;
+use rustc::util::nodemap::{FxHashMap, FxHashSet};
+use rustc_index::vec::IndexVec;
+use rustc_target::spec::abi::Abi;
+use syntax::ast::{self, Attribute, AttrStyle, AttrKind, Ident};
+use syntax::attr;
+use syntax::util::comments;
+use syntax::source_map::DUMMY_SP;
+use syntax_pos::hygiene::MacroKind;
+use syntax_pos::symbol::{Symbol, sym};
+use syntax_pos::{self, FileName};
+
+use crate::core::DocContext;
+use crate::clean::cfg::Cfg;
+use crate::clean::inline;
+use crate::clean::external_path;
+use crate::clean::types::Type::{QPath, ResolvedPath};
+use crate::doctree;
+use crate::html::item_type::ItemType;
+use crate::html::render::{cache, ExternalLocation};
+
+use self::Type::*;
+use self::ItemEnum::*;
+use self::SelfTy::*;
+use self::FunctionRetTy::*;
+
+thread_local!(pub static MAX_DEF_ID: RefCell<FxHashMap<CrateNum, DefId>> = Default::default());
+
+#[derive(Clone, Debug)]
+pub struct Crate {
+    pub name: String,
+    pub version: Option<String>,
+    pub src: FileName,
+    pub module: Option<Item>,
+    pub externs: Vec<(CrateNum, ExternalCrate)>,
+    pub primitives: Vec<(DefId, PrimitiveType, Attributes)>,
+    // These are later on moved into `CACHEKEY`, leaving the map empty.
+    // Only here so that they can be filtered through the rustdoc passes.
+    pub external_traits: Rc<RefCell<FxHashMap<DefId, Trait>>>,
+    pub masked_crates: FxHashSet<CrateNum>,
+    pub collapsed: bool,
+}
+
+#[derive(Clone, Debug)]
+pub struct ExternalCrate {
+    pub name: String,
+    pub src: FileName,
+    pub attrs: Attributes,
+    pub primitives: Vec<(DefId, PrimitiveType, Attributes)>,
+    pub keywords: Vec<(DefId, String, Attributes)>,
+}
+
+/// Anything with a source location and set of attributes and, optionally, a
+/// name. That is, anything that can be documented. This doesn't correspond
+/// directly to the AST's concept of an item; it's a strict superset.
+#[derive(Clone)]
+pub struct Item {
+    /// Stringified span
+    pub source: Span,
+    /// Not everything has a name. E.g., impls
+    pub name: Option<String>,
+    pub attrs: Attributes,
+    pub inner: ItemEnum,
+    pub visibility: Visibility,
+    pub def_id: DefId,
+    pub stability: Option<Stability>,
+    pub deprecation: Option<Deprecation>,
+}
+
+impl fmt::Debug for Item {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let fake = MAX_DEF_ID.with(|m| m.borrow().get(&self.def_id.krate)
+                                   .map(|id| self.def_id >= *id).unwrap_or(false));
+        let def_id: &dyn fmt::Debug = if fake { &"**FAKE**" } else { &self.def_id };
+
+        fmt.debug_struct("Item")
+            .field("source", &self.source)
+            .field("name", &self.name)
+            .field("attrs", &self.attrs)
+            .field("inner", &self.inner)
+            .field("visibility", &self.visibility)
+            .field("def_id", def_id)
+            .field("stability", &self.stability)
+            .field("deprecation", &self.deprecation)
+            .finish()
+    }
+}
+
+impl Item {
+    /// Finds the `doc` attribute as a NameValue and returns the corresponding
+    /// value found.
+    pub fn doc_value(&self) -> Option<&str> {
+        self.attrs.doc_value()
+    }
+
+    /// Finds all `doc` attributes as NameValues and returns their corresponding values, joined
+    /// with newlines.
+    pub fn collapsed_doc_value(&self) -> Option<String> {
+        self.attrs.collapsed_doc_value()
+    }
+
+    pub fn links(&self) -> Vec<(String, String)> {
+        self.attrs.links(&self.def_id.krate)
+    }
+
+    pub fn is_crate(&self) -> bool {
+        match self.inner {
+            StrippedItem(box ModuleItem(Module { is_crate: true, ..})) |
+            ModuleItem(Module { is_crate: true, ..}) => true,
+            _ => false,
+        }
+    }
+    pub fn is_mod(&self) -> bool {
+        self.type_() == ItemType::Module
+    }
+    pub fn is_trait(&self) -> bool {
+        self.type_() == ItemType::Trait
+    }
+    pub fn is_struct(&self) -> bool {
+        self.type_() == ItemType::Struct
+    }
+    pub fn is_enum(&self) -> bool {
+        self.type_() == ItemType::Enum
+    }
+    pub fn is_variant(&self) -> bool {
+        self.type_() == ItemType::Variant
+    }
+    pub fn is_associated_type(&self) -> bool {
+        self.type_() == ItemType::AssocType
+    }
+    pub fn is_associated_const(&self) -> bool {
+        self.type_() == ItemType::AssocConst
+    }
+    pub fn is_method(&self) -> bool {
+        self.type_() == ItemType::Method
+    }
+    pub fn is_ty_method(&self) -> bool {
+        self.type_() == ItemType::TyMethod
+    }
+    pub fn is_typedef(&self) -> bool {
+        self.type_() == ItemType::Typedef
+    }
+    pub fn is_primitive(&self) -> bool {
+        self.type_() == ItemType::Primitive
+    }
+    pub fn is_union(&self) -> bool {
+        self.type_() == ItemType::Union
+    }
+    pub fn is_import(&self) -> bool {
+        self.type_() == ItemType::Import
+    }
+    pub fn is_extern_crate(&self) -> bool {
+        self.type_() == ItemType::ExternCrate
+    }
+    pub fn is_keyword(&self) -> bool {
+        self.type_() == ItemType::Keyword
+    }
+    pub fn is_stripped(&self) -> bool {
+        match self.inner { StrippedItem(..) => true, _ => false }
+    }
+    pub fn has_stripped_fields(&self) -> Option<bool> {
+        match self.inner {
+            StructItem(ref _struct) => Some(_struct.fields_stripped),
+            UnionItem(ref union) => Some(union.fields_stripped),
+            VariantItem(Variant { kind: VariantKind::Struct(ref vstruct)} ) => {
+                Some(vstruct.fields_stripped)
+            },
+            _ => None,
+        }
+    }
+
+    pub fn stability_class(&self) -> Option<String> {
+        self.stability.as_ref().and_then(|ref s| {
+            let mut classes = Vec::with_capacity(2);
+
+            if s.level == stability::Unstable {
+                classes.push("unstable");
+            }
+
+            if s.deprecation.is_some() {
+                classes.push("deprecated");
+            }
+
+            if classes.len() != 0 {
+                Some(classes.join(" "))
+            } else {
+                None
+            }
+        })
+    }
+
+    pub fn stable_since(&self) -> Option<&str> {
+        self.stability.as_ref().map(|s| &s.since[..])
+    }
+
+    pub fn is_non_exhaustive(&self) -> bool {
+        self.attrs.other_attrs.iter()
+            .any(|a| a.check_name(sym::non_exhaustive))
+    }
+
+    /// Returns a documentation-level item type from the item.
+    pub fn type_(&self) -> ItemType {
+        ItemType::from(self)
+    }
+
+    /// Returns the info in the item's `#[deprecated]` or `#[rustc_deprecated]` attributes.
+    ///
+    /// If the item is not deprecated, returns `None`.
+    pub fn deprecation(&self) -> Option<&Deprecation> {
+        self.deprecation
+            .as_ref()
+            .or_else(|| self.stability.as_ref().and_then(|s| s.deprecation.as_ref()))
+    }
+    pub fn is_default(&self) -> bool {
+        match self.inner {
+            ItemEnum::MethodItem(ref meth) => {
+                if let Some(defaultness) = meth.defaultness {
+                    defaultness.has_value() && !defaultness.is_final()
+                } else {
+                    false
+                }
+            }
+            _ => false,
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum ItemEnum {
+    ExternCrateItem(String, Option<String>),
+    ImportItem(Import),
+    StructItem(Struct),
+    UnionItem(Union),
+    EnumItem(Enum),
+    FunctionItem(Function),
+    ModuleItem(Module),
+    TypedefItem(Typedef, bool /* is associated type */),
+    OpaqueTyItem(OpaqueTy, bool /* is associated type */),
+    StaticItem(Static),
+    ConstantItem(Constant),
+    TraitItem(Trait),
+    TraitAliasItem(TraitAlias),
+    ImplItem(Impl),
+    /// A method signature only. Used for required methods in traits (ie,
+    /// non-default-methods).
+    TyMethodItem(TyMethod),
+    /// A method with a body.
+    MethodItem(Method),
+    StructFieldItem(Type),
+    VariantItem(Variant),
+    /// `fn`s from an extern block
+    ForeignFunctionItem(Function),
+    /// `static`s from an extern block
+    ForeignStaticItem(Static),
+    /// `type`s from an extern block
+    ForeignTypeItem,
+    MacroItem(Macro),
+    ProcMacroItem(ProcMacro),
+    PrimitiveItem(PrimitiveType),
+    AssocConstItem(Type, Option<String>),
+    AssocTypeItem(Vec<GenericBound>, Option<Type>),
+    /// An item that has been stripped by a rustdoc pass
+    StrippedItem(Box<ItemEnum>),
+    KeywordItem(String),
+}
+
+impl ItemEnum {
+    pub fn is_associated(&self) -> bool {
+        match *self {
+            ItemEnum::TypedefItem(_, _) |
+            ItemEnum::AssocTypeItem(_, _) => true,
+            _ => false,
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct Module {
+    pub items: Vec<Item>,
+    pub is_crate: bool,
+}
+
+pub struct ListAttributesIter<'a> {
+    attrs: slice::Iter<'a, ast::Attribute>,
+    current_list: vec::IntoIter<ast::NestedMetaItem>,
+    name: Symbol,
+}
+
+impl<'a> Iterator for ListAttributesIter<'a> {
+    type Item = ast::NestedMetaItem;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(nested) = self.current_list.next() {
+            return Some(nested);
+        }
+
+        for attr in &mut self.attrs {
+            if let Some(list) = attr.meta_item_list() {
+                if attr.check_name(self.name) {
+                    self.current_list = list.into_iter();
+                    if let Some(nested) = self.current_list.next() {
+                        return Some(nested);
+                    }
+                }
+            }
+        }
+
+        None
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let lower = self.current_list.len();
+        (lower, None)
+    }
+}
+
+pub trait AttributesExt {
+    /// Finds an attribute as List and returns the list of attributes nested inside.
+    fn lists(&self, name: Symbol) -> ListAttributesIter<'_>;
+}
+
+impl AttributesExt for [ast::Attribute] {
+    fn lists(&self, name: Symbol) -> ListAttributesIter<'_> {
+        ListAttributesIter {
+            attrs: self.iter(),
+            current_list: Vec::new().into_iter(),
+            name,
+        }
+    }
+}
+
+pub trait NestedAttributesExt {
+    /// Returns `true` if the attribute list contains a specific `Word`
+    fn has_word(self, word: Symbol) -> bool;
+}
+
+impl<I: IntoIterator<Item=ast::NestedMetaItem>> NestedAttributesExt for I {
+    fn has_word(self, word: Symbol) -> bool {
+        self.into_iter().any(|attr| attr.is_word() && attr.check_name(word))
+    }
+}
+
+/// A portion of documentation, extracted from a `#[doc]` attribute.
+///
+/// Each variant contains the line number within the complete doc-comment where the fragment
+/// starts, as well as the Span where the corresponding doc comment or attribute is located.
+///
+/// Included files are kept separate from inline doc comments so that proper line-number
+/// information can be given when a doctest fails. Sugared doc comments and "raw" doc comments are
+/// kept separate because of issue #42760.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum DocFragment {
+    /// A doc fragment created from a `///` or `//!` doc comment.
+    SugaredDoc(usize, syntax_pos::Span, String),
+    /// A doc fragment created from a "raw" `#[doc=""]` attribute.
+    RawDoc(usize, syntax_pos::Span, String),
+    /// A doc fragment created from a `#[doc(include="filename")]` attribute. Contains both the
+    /// given filename and the file contents.
+    Include(usize, syntax_pos::Span, String, String),
+}
+
+impl DocFragment {
+    pub fn as_str(&self) -> &str {
+        match *self {
+            DocFragment::SugaredDoc(_, _, ref s) => &s[..],
+            DocFragment::RawDoc(_, _, ref s) => &s[..],
+            DocFragment::Include(_, _, _, ref s) => &s[..],
+        }
+    }
+
+    pub fn span(&self) -> syntax_pos::Span {
+        match *self {
+            DocFragment::SugaredDoc(_, span, _) |
+                DocFragment::RawDoc(_, span, _) |
+                DocFragment::Include(_, span, _, _) => span,
+        }
+    }
+}
+
+impl<'a> FromIterator<&'a DocFragment> for String {
+    fn from_iter<T>(iter: T) -> Self
+    where
+        T: IntoIterator<Item = &'a DocFragment>
+    {
+        iter.into_iter().fold(String::new(), |mut acc, frag| {
+            if !acc.is_empty() {
+                acc.push('\n');
+            }
+            match *frag {
+                DocFragment::SugaredDoc(_, _, ref docs)
+                    | DocFragment::RawDoc(_, _, ref docs)
+                    | DocFragment::Include(_, _, _, ref docs) =>
+                    acc.push_str(docs),
+            }
+
+            acc
+        })
+    }
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct Attributes {
+    pub doc_strings: Vec<DocFragment>,
+    pub other_attrs: Vec<ast::Attribute>,
+    pub cfg: Option<Arc<Cfg>>,
+    pub span: Option<syntax_pos::Span>,
+    /// map from Rust paths to resolved defs and potential URL fragments
+    pub links: Vec<(String, Option<DefId>, Option<String>)>,
+    pub inner_docs: bool,
+}
+
+impl Attributes {
+    /// Extracts the content from an attribute `#[doc(cfg(content))]`.
+    pub fn extract_cfg(mi: &ast::MetaItem) -> Option<&ast::MetaItem> {
+        use syntax::ast::NestedMetaItem::MetaItem;
+
+        if let ast::MetaItemKind::List(ref nmis) = mi.kind {
+            if nmis.len() == 1 {
+                if let MetaItem(ref cfg_mi) = nmis[0] {
+                    if cfg_mi.check_name(sym::cfg) {
+                        if let ast::MetaItemKind::List(ref cfg_nmis) = cfg_mi.kind {
+                            if cfg_nmis.len() == 1 {
+                                if let MetaItem(ref content_mi) = cfg_nmis[0] {
+                                    return Some(content_mi);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        None
+    }
+
+    /// Reads a `MetaItem` from within an attribute, looks for whether it is a
+    /// `#[doc(include="file")]`, and returns the filename and contents of the file as loaded from
+    /// its expansion.
+    pub fn extract_include(mi: &ast::MetaItem) -> Option<(String, String)> {
+        mi.meta_item_list().and_then(|list| {
+            for meta in list {
+                if meta.check_name(sym::include) {
+                    // the actual compiled `#[doc(include="filename")]` gets expanded to
+                    // `#[doc(include(file="filename", contents="file contents")]` so we need to
+                    // look for that instead
+                    return meta.meta_item_list().and_then(|list| {
+                        let mut filename: Option<String> = None;
+                        let mut contents: Option<String> = None;
+
+                        for it in list {
+                            if it.check_name(sym::file) {
+                                if let Some(name) = it.value_str() {
+                                    filename = Some(name.to_string());
+                                }
+                            } else if it.check_name(sym::contents) {
+                                if let Some(docs) = it.value_str() {
+                                    contents = Some(docs.to_string());
+                                }
+                            }
+                        }
+
+                        if let (Some(filename), Some(contents)) = (filename, contents) {
+                            Some((filename, contents))
+                        } else {
+                            None
+                        }
+                    });
+                }
+            }
+
+            None
+        })
+    }
+
+    pub fn has_doc_flag(&self, flag: Symbol) -> bool {
+        for attr in &self.other_attrs {
+            if !attr.check_name(sym::doc) { continue; }
+
+            if let Some(items) = attr.meta_item_list() {
+                if items.iter().filter_map(|i| i.meta_item()).any(|it| it.check_name(flag)) {
+                    return true;
+                }
+            }
+        }
+
+        false
+    }
+
+    pub fn from_ast(diagnostic: &::errors::Handler, attrs: &[ast::Attribute]) -> Attributes {
+        let mut doc_strings = vec![];
+        let mut sp = None;
+        let mut cfg = Cfg::True;
+        let mut doc_line = 0;
+
+        /// If `attr` is a doc comment, strips the leading and (if present)
+        /// trailing comments symbols, e.g. `///`, `/**`, and `*/`. Otherwise,
+        /// returns `attr` unchanged.
+        pub fn with_doc_comment_markers_stripped<T>(
+            attr: &Attribute,
+            f: impl FnOnce(&Attribute) -> T,
+        ) -> T {
+            match attr.kind {
+                AttrKind::Normal(_) => {
+                    f(attr)
+                }
+                AttrKind::DocComment(comment) => {
+                    let comment =
+                        Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str()));
+                    f(&Attribute {
+                        kind: AttrKind::DocComment(comment),
+                        id: attr.id,
+                        style: attr.style,
+                        span: attr.span,
+                    })
+                }
+            }
+        }
+
+        let other_attrs = attrs.iter().filter_map(|attr| {
+            with_doc_comment_markers_stripped(attr, |attr| {
+                if attr.check_name(sym::doc) {
+                    if let Some(mi) = attr.meta() {
+                        if let Some(value) = mi.value_str() {
+                            // Extracted #[doc = "..."]
+                            let value = value.to_string();
+                            let line = doc_line;
+                            doc_line += value.lines().count();
+
+                            if attr.is_doc_comment() {
+                                doc_strings.push(DocFragment::SugaredDoc(line, attr.span, value));
+                            } else {
+                                doc_strings.push(DocFragment::RawDoc(line, attr.span, value));
+                            }
+
+                            if sp.is_none() {
+                                sp = Some(attr.span);
+                            }
+                            return None;
+                        } else if let Some(cfg_mi) = Attributes::extract_cfg(&mi) {
+                            // Extracted #[doc(cfg(...))]
+                            match Cfg::parse(cfg_mi) {
+                                Ok(new_cfg) => cfg &= new_cfg,
+                                Err(e) => diagnostic.span_err(e.span, e.msg),
+                            }
+                            return None;
+                        } else if let Some((filename, contents)) = Attributes::extract_include(&mi)
+                        {
+                            let line = doc_line;
+                            doc_line += contents.lines().count();
+                            doc_strings.push(DocFragment::Include(line,
+                                                                  attr.span,
+                                                                  filename,
+                                                                  contents));
+                        }
+                    }
+                }
+                Some(attr.clone())
+            })
+        }).collect();
+
+        // treat #[target_feature(enable = "feat")] attributes as if they were
+        // #[doc(cfg(target_feature = "feat"))] attributes as well
+        for attr in attrs.lists(sym::target_feature) {
+            if attr.check_name(sym::enable) {
+                if let Some(feat) = attr.value_str() {
+                    let meta = attr::mk_name_value_item_str(
+                        Ident::with_dummy_span(sym::target_feature), feat, DUMMY_SP
+                    );
+                    if let Ok(feat_cfg) = Cfg::parse(&meta) {
+                        cfg &= feat_cfg;
+                    }
+                }
+            }
+        }
+
+        let inner_docs = attrs.iter()
+                              .filter(|a| a.check_name(sym::doc))
+                              .next()
+                              .map_or(true, |a| a.style == AttrStyle::Inner);
+
+        Attributes {
+            doc_strings,
+            other_attrs,
+            cfg: if cfg == Cfg::True { None } else { Some(Arc::new(cfg)) },
+            span: sp,
+            links: vec![],
+            inner_docs,
+        }
+    }
+
+    /// Finds the `doc` attribute as a NameValue and returns the corresponding
+    /// value found.
+    pub fn doc_value(&self) -> Option<&str> {
+        self.doc_strings.first().map(|s| s.as_str())
+    }
+
+    /// Finds all `doc` attributes as NameValues and returns their corresponding values, joined
+    /// with newlines.
+    pub fn collapsed_doc_value(&self) -> Option<String> {
+        if !self.doc_strings.is_empty() {
+            Some(self.doc_strings.iter().collect())
+        } else {
+            None
+        }
+    }
+
+    /// Gets links as a vector
+    ///
+    /// Cache must be populated before call
+    pub fn links(&self, krate: &CrateNum) -> Vec<(String, String)> {
+        use crate::html::format::href;
+
+        self.links.iter().filter_map(|&(ref s, did, ref fragment)| {
+            match did {
+                Some(did) => {
+                    if let Some((mut href, ..)) = href(did) {
+                        if let Some(ref fragment) = *fragment {
+                            href.push_str("#");
+                            href.push_str(fragment);
+                        }
+                        Some((s.clone(), href))
+                    } else {
+                        None
+                    }
+                }
+                None => {
+                    if let Some(ref fragment) = *fragment {
+                        let cache = cache();
+                        let url = match cache.extern_locations.get(krate) {
+                            Some(&(_, ref src, ExternalLocation::Local)) =>
+                                src.to_str().expect("invalid file path"),
+                            Some(&(_, _, ExternalLocation::Remote(ref s))) => s,
+                            Some(&(_, _, ExternalLocation::Unknown)) | None =>
+                                "https://doc.rust-lang.org/nightly",
+                        };
+                        // This is a primitive so the url is done "by hand".
+                        let tail = fragment.find('#').unwrap_or_else(|| fragment.len());
+                        Some((s.clone(),
+                              format!("{}{}std/primitive.{}.html{}",
+                                      url,
+                                      if !url.ends_with('/') { "/" } else { "" },
+                                      &fragment[..tail],
+                                      &fragment[tail..])))
+                    } else {
+                        panic!("This isn't a primitive?!");
+                    }
+                }
+            }
+        }).collect()
+    }
+}
+
+impl PartialEq for Attributes {
+    fn eq(&self, rhs: &Self) -> bool {
+        self.doc_strings == rhs.doc_strings &&
+        self.cfg == rhs.cfg &&
+        self.span == rhs.span &&
+        self.links == rhs.links &&
+        self.other_attrs.iter().map(|attr| attr.id).eq(rhs.other_attrs.iter().map(|attr| attr.id))
+    }
+}
+
+impl Eq for Attributes {}
+
+impl Hash for Attributes {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.doc_strings.hash(hasher);
+        self.cfg.hash(hasher);
+        self.span.hash(hasher);
+        self.links.hash(hasher);
+        for attr in &self.other_attrs {
+            attr.id.hash(hasher);
+        }
+    }
+}
+
+impl AttributesExt for Attributes {
+    fn lists(&self, name: Symbol) -> ListAttributesIter<'_> {
+        self.other_attrs.lists(name)
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum GenericBound {
+    TraitBound(PolyTrait, hir::TraitBoundModifier),
+    Outlives(Lifetime),
+}
+
+impl GenericBound {
+    pub fn maybe_sized(cx: &DocContext<'_>) -> GenericBound {
+        let did = cx.tcx.require_lang_item(lang_items::SizedTraitLangItem, None);
+        let empty = cx.tcx.intern_substs(&[]);
+        let path = external_path(cx, cx.tcx.item_name(did),
+            Some(did), false, vec![], empty);
+        inline::record_extern_fqn(cx, did, TypeKind::Trait);
+        GenericBound::TraitBound(PolyTrait {
+            trait_: ResolvedPath {
+                path,
+                param_names: None,
+                did,
+                is_generic: false,
+            },
+            generic_params: Vec::new(),
+        }, hir::TraitBoundModifier::Maybe)
+    }
+
+    pub fn is_sized_bound(&self, cx: &DocContext<'_>) -> bool {
+        use rustc::hir::TraitBoundModifier as TBM;
+        if let GenericBound::TraitBound(PolyTrait { ref trait_, .. }, TBM::None) = *self {
+            if trait_.def_id() == cx.tcx.lang_items().sized_trait() {
+                return true;
+            }
+        }
+        false
+    }
+
+    pub fn get_poly_trait(&self) -> Option<PolyTrait> {
+        if let GenericBound::TraitBound(ref p, _) = *self {
+            return Some(p.clone())
+        }
+        None
+    }
+
+    pub fn get_trait_type(&self) -> Option<Type> {
+        if let GenericBound::TraitBound(PolyTrait { ref trait_, .. }, _) = *self {
+            Some(trait_.clone())
+        } else {
+            None
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct Lifetime(pub String);
+
+impl Lifetime {
+    pub fn get_ref<'a>(&'a self) -> &'a str {
+        let Lifetime(ref s) = *self;
+        let s: &'a str = s;
+        s
+    }
+
+    pub fn statik() -> Lifetime {
+        Lifetime("'static".to_string())
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum WherePredicate {
+    BoundPredicate { ty: Type, bounds: Vec<GenericBound> },
+    RegionPredicate { lifetime: Lifetime, bounds: Vec<GenericBound> },
+    EqPredicate { lhs: Type, rhs: Type },
+}
+
+impl WherePredicate {
+    pub fn get_bounds(&self) -> Option<&[GenericBound]> {
+        match *self {
+            WherePredicate::BoundPredicate { ref bounds, .. } => Some(bounds),
+            WherePredicate::RegionPredicate { ref bounds, .. } => Some(bounds),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum GenericParamDefKind {
+    Lifetime,
+    Type {
+        did: DefId,
+        bounds: Vec<GenericBound>,
+        default: Option<Type>,
+        synthetic: Option<hir::SyntheticTyParamKind>,
+    },
+    Const {
+        did: DefId,
+        ty: Type,
+    },
+}
+
+impl GenericParamDefKind {
+    pub fn is_type(&self) -> bool {
+        match *self {
+            GenericParamDefKind::Type { .. } => true,
+            _ => false,
+        }
+    }
+
+    // FIXME(eddyb) this either returns the default of a type parameter, or the
+    // type of a `const` parameter. It seems that the intention is to *visit*
+    // any embedded types, but `get_type` seems to be the wrong name for that.
+    pub fn get_type(&self) -> Option<Type> {
+        match self {
+            GenericParamDefKind::Type { default, .. } => default.clone(),
+            GenericParamDefKind::Const { ty, .. } => Some(ty.clone()),
+            GenericParamDefKind::Lifetime => None,
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct GenericParamDef {
+    pub name: String,
+    pub kind: GenericParamDefKind,
+}
+
+impl GenericParamDef {
+    pub fn is_synthetic_type_param(&self) -> bool {
+        match self.kind {
+            GenericParamDefKind::Lifetime |
+            GenericParamDefKind::Const { .. } => false,
+            GenericParamDefKind::Type { ref synthetic, .. } => synthetic.is_some(),
+        }
+    }
+
+    pub fn is_type(&self) -> bool {
+        self.kind.is_type()
+    }
+
+    pub fn get_type(&self) -> Option<Type> {
+        self.kind.get_type()
+    }
+
+    pub fn get_bounds(&self) -> Option<&[GenericBound]> {
+        match self.kind {
+            GenericParamDefKind::Type { ref bounds, .. } => Some(bounds),
+            _ => None,
+        }
+    }
+}
+
+// maybe use a Generic enum and use Vec<Generic>?
+#[derive(Clone, Debug, Default)]
+pub struct Generics {
+    pub params: Vec<GenericParamDef>,
+    pub where_predicates: Vec<WherePredicate>,
+}
+
+#[derive(Clone, Debug)]
+pub struct Method {
+    pub generics: Generics,
+    pub decl: FnDecl,
+    pub header: hir::FnHeader,
+    pub defaultness: Option<hir::Defaultness>,
+    pub all_types: Vec<Type>,
+    pub ret_types: Vec<Type>,
+}
+
+#[derive(Clone, Debug)]
+pub struct TyMethod {
+    pub header: hir::FnHeader,
+    pub decl: FnDecl,
+    pub generics: Generics,
+    pub all_types: Vec<Type>,
+    pub ret_types: Vec<Type>,
+}
+
+#[derive(Clone, Debug)]
+pub struct Function {
+    pub decl: FnDecl,
+    pub generics: Generics,
+    pub header: hir::FnHeader,
+    pub all_types: Vec<Type>,
+    pub ret_types: Vec<Type>,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct FnDecl {
+    pub inputs: Arguments,
+    pub output: FunctionRetTy,
+    pub c_variadic: bool,
+    pub attrs: Attributes,
+}
+
+impl FnDecl {
+    pub fn self_type(&self) -> Option<SelfTy> {
+        self.inputs.values.get(0).and_then(|v| v.to_self())
+    }
+
+    /// Returns the sugared return type for an async function.
+    ///
+    /// For example, if the return type is `impl std::future::Future<Output = i32>`, this function
+    /// will return `i32`.
+    ///
+    /// # Panics
+    ///
+    /// This function will panic if the return type does not match the expected sugaring for async
+    /// functions.
+    pub fn sugared_async_return_type(&self) -> FunctionRetTy {
+        match &self.output {
+            FunctionRetTy::Return(Type::ImplTrait(bounds)) => {
+                match &bounds[0] {
+                    GenericBound::TraitBound(PolyTrait { trait_, .. }, ..) => {
+                        let bindings = trait_.bindings().unwrap();
+                        FunctionRetTy::Return(bindings[0].ty().clone())
+                    }
+                    _ => panic!("unexpected desugaring of async function"),
+                }
+            }
+            _ => panic!("unexpected desugaring of async function"),
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct Arguments {
+    pub values: Vec<Argument>,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct Argument {
+    pub type_: Type,
+    pub name: String,
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub enum SelfTy {
+    SelfValue,
+    SelfBorrowed(Option<Lifetime>, Mutability),
+    SelfExplicit(Type),
+}
+
+impl Argument {
+    pub fn to_self(&self) -> Option<SelfTy> {
+        if self.name != "self" {
+            return None;
+        }
+        if self.type_.is_self_type() {
+            return Some(SelfValue);
+        }
+        match self.type_ {
+            BorrowedRef{ref lifetime, mutability, ref type_} if type_.is_self_type() => {
+                Some(SelfBorrowed(lifetime.clone(), mutability))
+            }
+            _ => Some(SelfExplicit(self.type_.clone()))
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum FunctionRetTy {
+    Return(Type),
+    DefaultReturn,
+}
+
+impl GetDefId for FunctionRetTy {
+    fn def_id(&self) -> Option<DefId> {
+        match *self {
+            Return(ref ty) => ty.def_id(),
+            DefaultReturn => None,
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct Trait {
+    pub auto: bool,
+    pub unsafety: hir::Unsafety,
+    pub items: Vec<Item>,
+    pub generics: Generics,
+    pub bounds: Vec<GenericBound>,
+    pub is_spotlight: bool,
+    pub is_auto: bool,
+}
+
+#[derive(Clone, Debug)]
+pub struct TraitAlias {
+    pub generics: Generics,
+    pub bounds: Vec<GenericBound>,
+}
+
+/// A trait reference, which may have higher ranked lifetimes.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct PolyTrait {
+    pub trait_: Type,
+    pub generic_params: Vec<GenericParamDef>,
+}
+
+/// A representation of a type suitable for hyperlinking purposes. Ideally, one can get the original
+/// type out of the AST/`TyCtxt` given one of these, if more information is needed. Most
+/// importantly, it does not preserve mutability or boxes.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum Type {
+    /// Structs/enums/traits (most that would be an `hir::TyKind::Path`).
+    ResolvedPath {
+        path: Path,
+        param_names: Option<Vec<GenericBound>>,
+        did: DefId,
+        /// `true` if is a `T::Name` path for associated types.
+        is_generic: bool,
+    },
+    /// For parameterized types, so the consumer of the JSON don't go
+    /// looking for types which don't exist anywhere.
+    Generic(String),
+    /// Primitives are the fixed-size numeric types (plus int/usize/float), char,
+    /// arrays, slices, and tuples.
+    Primitive(PrimitiveType),
+    /// `extern "ABI" fn`
+    BareFunction(Box<BareFunctionDecl>),
+    Tuple(Vec<Type>),
+    Slice(Box<Type>),
+    Array(Box<Type>, String),
+    Never,
+    RawPointer(Mutability, Box<Type>),
+    BorrowedRef {
+        lifetime: Option<Lifetime>,
+        mutability: Mutability,
+        type_: Box<Type>,
+    },
+
+    // `<Type as Trait>::Name`
+    QPath {
+        name: String,
+        self_type: Box<Type>,
+        trait_: Box<Type>
+    },
+
+    // `_`
+    Infer,
+
+    // `impl TraitA + TraitB + ...`
+    ImplTrait(Vec<GenericBound>),
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Copy, Debug)]
+pub enum PrimitiveType {
+    Isize, I8, I16, I32, I64, I128,
+    Usize, U8, U16, U32, U64, U128,
+    F32, F64,
+    Char,
+    Bool,
+    Str,
+    Slice,
+    Array,
+    Tuple,
+    Unit,
+    RawPointer,
+    Reference,
+    Fn,
+    Never,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub enum TypeKind {
+    Enum,
+    Function,
+    Module,
+    Const,
+    Static,
+    Struct,
+    Union,
+    Trait,
+    Typedef,
+    Foreign,
+    Macro,
+    Attr,
+    Derive,
+    TraitAlias,
+}
+
+pub trait GetDefId {
+    fn def_id(&self) -> Option<DefId>;
+}
+
+impl<T: GetDefId> GetDefId for Option<T> {
+    fn def_id(&self) -> Option<DefId> {
+        self.as_ref().and_then(|d| d.def_id())
+    }
+}
+
+impl Type {
+    pub fn primitive_type(&self) -> Option<PrimitiveType> {
+        match *self {
+            Primitive(p) | BorrowedRef { type_: box Primitive(p), ..} => Some(p),
+            Slice(..) | BorrowedRef { type_: box Slice(..), .. } => Some(PrimitiveType::Slice),
+            Array(..) | BorrowedRef { type_: box Array(..), .. } => Some(PrimitiveType::Array),
+            Tuple(ref tys) => if tys.is_empty() {
+                Some(PrimitiveType::Unit)
+            } else {
+                Some(PrimitiveType::Tuple)
+            },
+            RawPointer(..) => Some(PrimitiveType::RawPointer),
+            BorrowedRef { type_: box Generic(..), .. } => Some(PrimitiveType::Reference),
+            BareFunction(..) => Some(PrimitiveType::Fn),
+            Never => Some(PrimitiveType::Never),
+            _ => None,
+        }
+    }
+
+    pub fn is_generic(&self) -> bool {
+        match *self {
+            ResolvedPath { is_generic, .. } => is_generic,
+            _ => false,
+        }
+    }
+
+    pub fn is_self_type(&self) -> bool {
+        match *self {
+            Generic(ref name) => name == "Self",
+            _ => false
+        }
+    }
+
+    pub fn generics(&self) -> Option<Vec<Type>> {
+        match *self {
+            ResolvedPath { ref path, .. } => {
+                path.segments.last().and_then(|seg| {
+                    if let GenericArgs::AngleBracketed { ref args, .. } = seg.args {
+                        Some(args.iter().filter_map(|arg| match arg {
+                            GenericArg::Type(ty) => Some(ty.clone()),
+                            _ => None,
+                        }).collect())
+                    } else {
+                        None
+                    }
+                })
+            }
+            _ => None,
+        }
+    }
+
+    pub fn bindings(&self) -> Option<&[TypeBinding]> {
+        match *self {
+            ResolvedPath { ref path, .. } => {
+                path.segments.last().and_then(|seg| {
+                    if let GenericArgs::AngleBracketed { ref bindings, .. } = seg.args {
+                        Some(&**bindings)
+                    } else {
+                        None
+                    }
+                })
+            }
+            _ => None
+        }
+    }
+
+    pub fn is_full_generic(&self) -> bool {
+        match *self {
+            Type::Generic(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn projection(&self) -> Option<(&Type, DefId, &str)> {
+        let (self_, trait_, name) = match self {
+            QPath { ref self_type, ref trait_, ref name } => {
+                (self_type, trait_, name)
+            }
+            _ => return None,
+        };
+        let trait_did = match **trait_ {
+            ResolvedPath { did, .. } => did,
+            _ => return None,
+        };
+        Some((&self_, trait_did, name))
+    }
+
+}
+
+impl GetDefId for Type {
+    fn def_id(&self) -> Option<DefId> {
+        match *self {
+            ResolvedPath { did, .. } => Some(did),
+            Primitive(p) => crate::html::render::cache().primitive_locations.get(&p).cloned(),
+            BorrowedRef { type_: box Generic(..), .. } =>
+                Primitive(PrimitiveType::Reference).def_id(),
+            BorrowedRef { ref type_, .. } => type_.def_id(),
+            Tuple(ref tys) => if tys.is_empty() {
+                Primitive(PrimitiveType::Unit).def_id()
+            } else {
+                Primitive(PrimitiveType::Tuple).def_id()
+            },
+            BareFunction(..) => Primitive(PrimitiveType::Fn).def_id(),
+            Never => Primitive(PrimitiveType::Never).def_id(),
+            Slice(..) => Primitive(PrimitiveType::Slice).def_id(),
+            Array(..) => Primitive(PrimitiveType::Array).def_id(),
+            RawPointer(..) => Primitive(PrimitiveType::RawPointer).def_id(),
+            QPath { ref self_type, .. } => self_type.def_id(),
+            _ => None,
+        }
+    }
+}
+
+impl PrimitiveType {
+    pub fn from_str(s: &str) -> Option<PrimitiveType> {
+        match s {
+            "isize" => Some(PrimitiveType::Isize),
+            "i8" => Some(PrimitiveType::I8),
+            "i16" => Some(PrimitiveType::I16),
+            "i32" => Some(PrimitiveType::I32),
+            "i64" => Some(PrimitiveType::I64),
+            "i128" => Some(PrimitiveType::I128),
+            "usize" => Some(PrimitiveType::Usize),
+            "u8" => Some(PrimitiveType::U8),
+            "u16" => Some(PrimitiveType::U16),
+            "u32" => Some(PrimitiveType::U32),
+            "u64" => Some(PrimitiveType::U64),
+            "u128" => Some(PrimitiveType::U128),
+            "bool" => Some(PrimitiveType::Bool),
+            "char" => Some(PrimitiveType::Char),
+            "str" => Some(PrimitiveType::Str),
+            "f32" => Some(PrimitiveType::F32),
+            "f64" => Some(PrimitiveType::F64),
+            "array" => Some(PrimitiveType::Array),
+            "slice" => Some(PrimitiveType::Slice),
+            "tuple" => Some(PrimitiveType::Tuple),
+            "unit" => Some(PrimitiveType::Unit),
+            "pointer" => Some(PrimitiveType::RawPointer),
+            "reference" => Some(PrimitiveType::Reference),
+            "fn" => Some(PrimitiveType::Fn),
+            "never" => Some(PrimitiveType::Never),
+            _ => None,
+        }
+    }
+
+    pub fn as_str(&self) -> &'static str {
+        use self::PrimitiveType::*;
+        match *self {
+            Isize => "isize",
+            I8 => "i8",
+            I16 => "i16",
+            I32 => "i32",
+            I64 => "i64",
+            I128 => "i128",
+            Usize => "usize",
+            U8 => "u8",
+            U16 => "u16",
+            U32 => "u32",
+            U64 => "u64",
+            U128 => "u128",
+            F32 => "f32",
+            F64 => "f64",
+            Str => "str",
+            Bool => "bool",
+            Char => "char",
+            Array => "array",
+            Slice => "slice",
+            Tuple => "tuple",
+            Unit => "unit",
+            RawPointer => "pointer",
+            Reference => "reference",
+            Fn => "fn",
+            Never => "never",
+        }
+    }
+
+    pub fn to_url_str(&self) -> &'static str {
+        self.as_str()
+    }
+}
+
+impl From<ast::IntTy> for PrimitiveType {
+    fn from(int_ty: ast::IntTy) -> PrimitiveType {
+        match int_ty {
+            ast::IntTy::Isize => PrimitiveType::Isize,
+            ast::IntTy::I8 => PrimitiveType::I8,
+            ast::IntTy::I16 => PrimitiveType::I16,
+            ast::IntTy::I32 => PrimitiveType::I32,
+            ast::IntTy::I64 => PrimitiveType::I64,
+            ast::IntTy::I128 => PrimitiveType::I128,
+        }
+    }
+}
+
+impl From<ast::UintTy> for PrimitiveType {
+    fn from(uint_ty: ast::UintTy) -> PrimitiveType {
+        match uint_ty {
+            ast::UintTy::Usize => PrimitiveType::Usize,
+            ast::UintTy::U8 => PrimitiveType::U8,
+            ast::UintTy::U16 => PrimitiveType::U16,
+            ast::UintTy::U32 => PrimitiveType::U32,
+            ast::UintTy::U64 => PrimitiveType::U64,
+            ast::UintTy::U128 => PrimitiveType::U128,
+        }
+    }
+}
+
+impl From<ast::FloatTy> for PrimitiveType {
+    fn from(float_ty: ast::FloatTy) -> PrimitiveType {
+        match float_ty {
+            ast::FloatTy::F32 => PrimitiveType::F32,
+            ast::FloatTy::F64 => PrimitiveType::F64,
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum Visibility {
+    Public,
+    Inherited,
+    Crate,
+    Restricted(DefId, Path),
+}
+
+#[derive(Clone, Debug)]
+pub struct Struct {
+    pub struct_type: doctree::StructType,
+    pub generics: Generics,
+    pub fields: Vec<Item>,
+    pub fields_stripped: bool,
+}
+
+#[derive(Clone, Debug)]
+pub struct Union {
+    pub struct_type: doctree::StructType,
+    pub generics: Generics,
+    pub fields: Vec<Item>,
+    pub fields_stripped: bool,
+}
+
+/// This is a more limited form of the standard Struct, different in that
+/// it lacks the things most items have (name, id, parameterization). Found
+/// only as a variant in an enum.
+#[derive(Clone, Debug)]
+pub struct VariantStruct {
+    pub struct_type: doctree::StructType,
+    pub fields: Vec<Item>,
+    pub fields_stripped: bool,
+}
+
+#[derive(Clone, Debug)]
+pub struct Enum {
+    pub variants: IndexVec<VariantIdx, Item>,
+    pub generics: Generics,
+    pub variants_stripped: bool,
+}
+
+#[derive(Clone, Debug)]
+pub struct Variant {
+    pub kind: VariantKind,
+}
+
+#[derive(Clone, Debug)]
+pub enum VariantKind {
+    CLike,
+    Tuple(Vec<Type>),
+    Struct(VariantStruct),
+}
+
+#[derive(Clone, Debug)]
+pub struct Span {
+    pub filename: FileName,
+    pub loline: usize,
+    pub locol: usize,
+    pub hiline: usize,
+    pub hicol: usize,
+    pub original: syntax_pos::Span,
+}
+
+impl Span {
+    pub fn empty() -> Span {
+        Span {
+            filename: FileName::Anon(0),
+            loline: 0, locol: 0,
+            hiline: 0, hicol: 0,
+            original: syntax_pos::DUMMY_SP,
+        }
+    }
+
+    pub fn span(&self) -> syntax_pos::Span {
+        self.original
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct Path {
+    pub global: bool,
+    pub res: Res,
+    pub segments: Vec<PathSegment>,
+}
+
+impl Path {
+    pub fn last_name(&self) -> &str {
+        self.segments.last().expect("segments were empty").name.as_str()
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum GenericArg {
+    Lifetime(Lifetime),
+    Type(Type),
+    Const(Constant),
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum GenericArgs {
+    AngleBracketed {
+        args: Vec<GenericArg>,
+        bindings: Vec<TypeBinding>,
+    },
+    Parenthesized {
+        inputs: Vec<Type>,
+        output: Option<Type>,
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct PathSegment {
+    pub name: String,
+    pub args: GenericArgs,
+}
+
+#[derive(Clone, Debug)]
+pub struct Typedef {
+    pub type_: Type,
+    pub generics: Generics,
+}
+
+#[derive(Clone, Debug)]
+pub struct OpaqueTy {
+    pub bounds: Vec<GenericBound>,
+    pub generics: Generics,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct BareFunctionDecl {
+    pub unsafety: hir::Unsafety,
+    pub generic_params: Vec<GenericParamDef>,
+    pub decl: FnDecl,
+    pub abi: Abi,
+}
+
+#[derive(Clone, Debug)]
+pub struct Static {
+    pub type_: Type,
+    pub mutability: Mutability,
+    /// It's useful to have the value of a static documented, but I have no
+    /// desire to represent expressions (that'd basically be all of the AST,
+    /// which is huge!). So, have a string.
+    pub expr: String,
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
+pub struct Constant {
+    pub type_: Type,
+    pub expr: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Copy, Hash)]
+pub enum Mutability {
+    Mutable,
+    Immutable,
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub enum ImplPolarity {
+    Positive,
+    Negative,
+}
+
+#[derive(Clone, Debug)]
+pub struct Impl {
+    pub unsafety: hir::Unsafety,
+    pub generics: Generics,
+    pub provided_trait_methods: FxHashSet<String>,
+    pub trait_: Option<Type>,
+    pub for_: Type,
+    pub items: Vec<Item>,
+    pub polarity: Option<ImplPolarity>,
+    pub synthetic: bool,
+    pub blanket_impl: Option<Type>,
+}
+
+#[derive(Clone, Debug)]
+pub enum Import {
+    // use source as str;
+    Simple(String, ImportSource),
+    // use source::*;
+    Glob(ImportSource)
+}
+
+#[derive(Clone, Debug)]
+pub struct ImportSource {
+    pub path: Path,
+    pub did: Option<DefId>,
+}
+
+#[derive(Clone, Debug)]
+pub struct Macro {
+    pub source: String,
+    pub imported_from: Option<String>,
+}
+
+#[derive(Clone, Debug)]
+pub struct ProcMacro {
+    pub kind: MacroKind,
+    pub helpers: Vec<String>,
+}
+
+#[derive(Clone, Debug)]
+pub struct Stability {
+    pub level: stability::StabilityLevel,
+    pub feature: Option<String>,
+    pub since: String,
+    pub deprecation: Option<Deprecation>,
+    pub unstable_reason: Option<String>,
+    pub issue: Option<NonZeroU32>,
+}
+
+#[derive(Clone, Debug)]
+pub struct Deprecation {
+    pub since: Option<String>,
+    pub note: Option<String>,
+}
+
+/// An type binding on an associated type (e.g., `A = Bar` in `Foo<A = Bar>` or
+/// `A: Send + Sync` in `Foo<A: Send + Sync>`).
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct TypeBinding {
+    pub name: String,
+    pub kind: TypeBindingKind,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum TypeBindingKind {
+    Equality {
+        ty: Type,
+    },
+    Constraint {
+        bounds: Vec<GenericBound>,
+    },
+}
+
+impl TypeBinding {
+    pub fn ty(&self) -> &Type {
+        match self.kind {
+            TypeBindingKind::Equality { ref ty } => ty,
+            _ => panic!("expected equality type binding for parenthesized generic args"),
+        }
+    }
+}
diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 1f839f1..8db7bc1 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -54,7 +54,5 @@
         }
         println!("cargo:rustc-link-lib=c");
         println!("cargo:rustc-link-lib=compiler_rt");
-    } else if target.contains("hermit") {
-        println!("cargo:rustc-link-lib=hermit");
     }
 }
diff --git a/src/libstd/fs.rs b/src/libstd/fs.rs
index e5cf022..a109e38 100644
--- a/src/libstd/fs.rs
+++ b/src/libstd/fs.rs
@@ -2339,8 +2339,10 @@
         let filename = &tmpdir.join("file_that_does_not_exist.txt");
         let result = File::open(filename);
 
-        #[cfg(unix)]
+        #[cfg(all(unix, not(target_os = "vxworks")))]
         error!(result, "No such file or directory");
+        #[cfg(target_os = "vxworks")]
+        error!(result, "no such file or directory");
         #[cfg(windows)]
         error!(result, 2); // ERROR_FILE_NOT_FOUND
     }
@@ -2352,8 +2354,10 @@
 
         let result = fs::remove_file(filename);
 
-        #[cfg(unix)]
+        #[cfg(all(unix, not(target_os = "vxworks")))]
         error!(result, "No such file or directory");
+        #[cfg(target_os = "vxworks")]
+        error!(result, "no such file or directory");
         #[cfg(windows)]
         error!(result, 2); // ERROR_FILE_NOT_FOUND
     }
@@ -2553,7 +2557,10 @@
 
         check!(fs::set_permissions(filename, fs::Permissions::from_mode(0o1777)));
         let metadata1 = check!(fs::metadata(filename));
+        #[cfg(all(unix, not(target_os = "vxworks")))]
         assert_eq!(mask & metadata1.permissions().mode(), 0o1777);
+        #[cfg(target_os = "vxworks")]
+        assert_eq!(mask & metadata1.permissions().mode(), 0o0777);
     }
 
     #[test]
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 20c1c5c..a1a33ba 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -987,7 +987,6 @@
     /// #![feature(io_slice_advance)]
     ///
     /// use std::io::IoSliceMut;
-    /// use std::mem;
     /// use std::ops::Deref;
     ///
     /// let mut buf1 = [1; 8];
@@ -1000,7 +999,7 @@
     /// ][..];
     ///
     /// // Mark 10 bytes as read.
-    /// bufs = IoSliceMut::advance(mem::replace(&mut bufs, &mut []), 10);
+    /// bufs = IoSliceMut::advance(bufs, 10);
     /// assert_eq!(bufs[0].deref(), [2; 14].as_ref());
     /// assert_eq!(bufs[1].deref(), [3; 8].as_ref());
     /// ```
@@ -1090,20 +1089,19 @@
     /// #![feature(io_slice_advance)]
     ///
     /// use std::io::IoSlice;
-    /// use std::mem;
     /// use std::ops::Deref;
     ///
-    /// let mut buf1 = [1; 8];
-    /// let mut buf2 = [2; 16];
-    /// let mut buf3 = [3; 8];
+    /// let buf1 = [1; 8];
+    /// let buf2 = [2; 16];
+    /// let buf3 = [3; 8];
     /// let mut bufs = &mut [
-    ///     IoSlice::new(&mut buf1),
-    ///     IoSlice::new(&mut buf2),
-    ///     IoSlice::new(&mut buf3),
+    ///     IoSlice::new(&buf1),
+    ///     IoSlice::new(&buf2),
+    ///     IoSlice::new(&buf3),
     /// ][..];
     ///
     /// // Mark 10 bytes as written.
-    /// bufs = IoSlice::advance(mem::replace(&mut bufs, &mut []), 10);
+    /// bufs = IoSlice::advance(bufs, 10);
     /// assert_eq!(bufs[0].deref(), [2; 14].as_ref());
     /// assert_eq!(bufs[1].deref(), [3; 8].as_ref());
     #[unstable(feature = "io_slice_advance", issue = "62726")]
@@ -2415,7 +2413,6 @@
     use crate::cmp;
     use crate::io::prelude::*;
     use crate::io::{self, IoSlice, IoSliceMut};
-    use crate::mem;
     use crate::ops::Deref;
 
     #[test]
@@ -2731,26 +2728,26 @@
         ][..];
 
         // Only in a single buffer..
-        bufs = IoSliceMut::advance(mem::replace(&mut bufs, &mut []), 1);
+        bufs = IoSliceMut::advance(bufs, 1);
         assert_eq!(bufs[0].deref(), [1; 7].as_ref());
         assert_eq!(bufs[1].deref(), [2; 16].as_ref());
         assert_eq!(bufs[2].deref(), [3; 8].as_ref());
 
         // Removing a buffer, leaving others as is.
-        bufs = IoSliceMut::advance(mem::replace(&mut bufs, &mut []), 7);
+        bufs = IoSliceMut::advance(bufs, 7);
         assert_eq!(bufs[0].deref(), [2; 16].as_ref());
         assert_eq!(bufs[1].deref(), [3; 8].as_ref());
 
         // Removing a buffer and removing from the next buffer.
-        bufs = IoSliceMut::advance(mem::replace(&mut bufs, &mut []), 18);
+        bufs = IoSliceMut::advance(bufs, 18);
         assert_eq!(bufs[0].deref(), [3; 6].as_ref());
     }
 
     #[test]
     fn io_slice_mut_advance_empty_slice() {
-        let mut empty_bufs = &mut [][..];
+        let empty_bufs = &mut [][..];
         // Shouldn't panic.
-        IoSliceMut::advance(&mut empty_bufs, 1);
+        IoSliceMut::advance(empty_bufs, 1);
     }
 
     #[test]
@@ -2759,48 +2756,48 @@
         let mut bufs = &mut [IoSliceMut::new(&mut buf1)][..];
 
         // Going beyond the total length should be ok.
-        bufs = IoSliceMut::advance(mem::replace(&mut bufs, &mut []), 9);
+        bufs = IoSliceMut::advance(bufs, 9);
         assert!(bufs.is_empty());
     }
 
     #[test]
     fn io_slice_advance() {
-        let mut buf1 = [1; 8];
-        let mut buf2 = [2; 16];
-        let mut buf3 = [3; 8];
+        let buf1 = [1; 8];
+        let buf2 = [2; 16];
+        let buf3 = [3; 8];
         let mut bufs =
-            &mut [IoSlice::new(&mut buf1), IoSlice::new(&mut buf2), IoSlice::new(&mut buf3)][..];
+            &mut [IoSlice::new(&buf1), IoSlice::new(&buf2), IoSlice::new(&buf3)][..];
 
         // Only in a single buffer..
-        bufs = IoSlice::advance(mem::replace(&mut bufs, &mut []), 1);
+        bufs = IoSlice::advance(bufs, 1);
         assert_eq!(bufs[0].deref(), [1; 7].as_ref());
         assert_eq!(bufs[1].deref(), [2; 16].as_ref());
         assert_eq!(bufs[2].deref(), [3; 8].as_ref());
 
         // Removing a buffer, leaving others as is.
-        bufs = IoSlice::advance(mem::replace(&mut bufs, &mut []), 7);
+        bufs = IoSlice::advance(bufs, 7);
         assert_eq!(bufs[0].deref(), [2; 16].as_ref());
         assert_eq!(bufs[1].deref(), [3; 8].as_ref());
 
         // Removing a buffer and removing from the next buffer.
-        bufs = IoSlice::advance(mem::replace(&mut bufs, &mut []), 18);
+        bufs = IoSlice::advance(bufs, 18);
         assert_eq!(bufs[0].deref(), [3; 6].as_ref());
     }
 
     #[test]
     fn io_slice_advance_empty_slice() {
-        let mut empty_bufs = &mut [][..];
+        let empty_bufs = &mut [][..];
         // Shouldn't panic.
-        IoSlice::advance(&mut empty_bufs, 1);
+        IoSlice::advance(empty_bufs, 1);
     }
 
     #[test]
     fn io_slice_advance_beyond_total_length() {
-        let mut buf1 = [1; 8];
-        let mut bufs = &mut [IoSlice::new(&mut buf1)][..];
+        let buf1 = [1; 8];
+        let mut bufs = &mut [IoSlice::new(&buf1)][..];
 
         // Going beyond the total length should be ok.
-        bufs = IoSlice::advance(mem::replace(&mut bufs, &mut []), 9);
+        bufs = IoSlice::advance(bufs, 9);
         assert!(bufs.is_empty());
     }
 }
diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs
index 5b7bef9..de7ced3 100644
--- a/src/libstd/keyword_docs.rs
+++ b/src/libstd/keyword_docs.rs
@@ -57,7 +57,7 @@
 /// 'outer: for i in 1..=5 {
 ///     println!("outer iteration (i): {}", i);
 ///
-///     'inner: for j in 1..=200 {
+///     '_inner: for j in 1..=200 {
 ///         println!("    inner iteration (j): {}", j);
 ///         if j >= 3 {
 ///             // breaks from inner loop, let's outer loop continue.
@@ -178,7 +178,7 @@
 ///```rust
 /// // Print Odd numbers under 30 with unit <= 5
 /// 'tens: for ten in 0..3 {
-///     'units: for unit in 0..=9 {
+///     '_units: for unit in 0..=9 {
 ///         if unit % 2 == 0 {
 ///             continue;
 ///         }
diff --git a/src/libstd/net/parser.rs b/src/libstd/net/parser.rs
index 8106d1c..686fa8c 100644
--- a/src/libstd/net/parser.rs
+++ b/src/libstd/net/parser.rs
@@ -44,19 +44,6 @@
         self.read_atomically(move |p| cb(p).filter(|_| p.is_eof()))
     }
 
-    // Return result of first successful parser
-    fn read_or<T>(
-        &mut self,
-        parsers: &mut [Box<dyn FnMut(&mut Parser<'_>) -> Option<T> + 'static>],
-    ) -> Option<T> {
-        for pf in parsers {
-            if let Some(r) = self.read_atomically(|p: &mut Parser<'_>| pf(p)) {
-                return Some(r);
-            }
-        }
-        None
-    }
-
     // Apply 3 parsers sequentially
     fn read_seq_3<A, B, C, PA, PB, PC>(&mut self, pa: PA, pb: PB, pc: PC) -> Option<(A, B, C)>
     where
@@ -235,9 +222,8 @@
     }
 
     fn read_ip_addr(&mut self) -> Option<IpAddr> {
-        let ipv4_addr = |p: &mut Parser<'_>| p.read_ipv4_addr().map(IpAddr::V4);
-        let ipv6_addr = |p: &mut Parser<'_>| p.read_ipv6_addr().map(IpAddr::V6);
-        self.read_or(&mut [Box::new(ipv4_addr), Box::new(ipv6_addr)])
+        self.read_ipv4_addr().map(IpAddr::V4)
+            .or_else(|| self.read_ipv6_addr().map(IpAddr::V6))
     }
 
     fn read_socket_addr_v4(&mut self) -> Option<SocketAddrV4> {
@@ -268,9 +254,8 @@
     }
 
     fn read_socket_addr(&mut self) -> Option<SocketAddr> {
-        let v4 = |p: &mut Parser<'_>| p.read_socket_addr_v4().map(SocketAddr::V4);
-        let v6 = |p: &mut Parser<'_>| p.read_socket_addr_v6().map(SocketAddr::V6);
-        self.read_or(&mut [Box::new(v4), Box::new(v6)])
+        self.read_socket_addr_v4().map(SocketAddr::V4)
+            .or_else(|| self.read_socket_addr_v6().map(SocketAddr::V6))
     }
 }
 
diff --git a/src/libstd/sync/mutex.rs b/src/libstd/sync/mutex.rs
index 87c2318..e90da69 100644
--- a/src/libstd/sync/mutex.rs
+++ b/src/libstd/sync/mutex.rs
@@ -143,10 +143,8 @@
 #[must_use = "if unused the Mutex will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct MutexGuard<'a, T: ?Sized + 'a> {
-    // funny underscores due to how Deref/DerefMut currently work (they
-    // disregard field privacy).
-    __lock: &'a Mutex<T>,
-    __poison: poison::Guard,
+    lock: &'a Mutex<T>,
+    poison: poison::Guard,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -417,8 +415,8 @@
     unsafe fn new(lock: &'mutex Mutex<T>) -> LockResult<MutexGuard<'mutex, T>> {
         poison::map_result(lock.poison.borrow(), |guard| {
             MutexGuard {
-                __lock: lock,
-                __poison: guard,
+                lock: lock,
+                poison: guard,
             }
         })
     }
@@ -429,14 +427,14 @@
     type Target = T;
 
     fn deref(&self) -> &T {
-        unsafe { &*self.__lock.data.get() }
+        unsafe { &*self.lock.data.get() }
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> DerefMut for MutexGuard<'_, T> {
     fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.__lock.data.get() }
+        unsafe { &mut *self.lock.data.get() }
     }
 }
 
@@ -445,8 +443,8 @@
     #[inline]
     fn drop(&mut self) {
         unsafe {
-            self.__lock.poison.done(&self.__poison);
-            self.__lock.inner.raw_unlock();
+            self.lock.poison.done(&self.poison);
+            self.lock.inner.raw_unlock();
         }
     }
 }
@@ -466,11 +464,11 @@
 }
 
 pub fn guard_lock<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a sys::Mutex {
-    &guard.__lock.inner
+    &guard.lock.inner
 }
 
 pub fn guard_poison<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a poison::Flag {
-    &guard.__lock.poison
+    &guard.lock.poison
 }
 
 #[cfg(all(test, not(target_os = "emscripten")))]
diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
index b1b56f3..c217291 100644
--- a/src/libstd/sync/rwlock.rs
+++ b/src/libstd/sync/rwlock.rs
@@ -87,7 +87,7 @@
 #[must_use = "if unused the RwLock will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
-    __lock: &'a RwLock<T>,
+    lock: &'a RwLock<T>,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -108,8 +108,8 @@
 #[must_use = "if unused the RwLock will immediately unlock"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
-    __lock: &'a RwLock<T>,
-    __poison: poison::Guard,
+    lock: &'a RwLock<T>,
+    poison: poison::Guard,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -465,7 +465,7 @@
                   -> LockResult<RwLockReadGuard<'rwlock, T>> {
         poison::map_result(lock.poison.borrow(), |_| {
             RwLockReadGuard {
-                __lock: lock,
+                lock: lock,
             }
         })
     }
@@ -476,8 +476,8 @@
                   -> LockResult<RwLockWriteGuard<'rwlock, T>> {
         poison::map_result(lock.poison.borrow(), |guard| {
             RwLockWriteGuard {
-                __lock: lock,
-                __poison: guard,
+                lock: lock,
+                poison: guard,
             }
         })
     }
@@ -487,7 +487,7 @@
 impl<T: fmt::Debug> fmt::Debug for RwLockReadGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("RwLockReadGuard")
-            .field("lock", &self.__lock)
+            .field("lock", &self.lock)
             .finish()
     }
 }
@@ -503,7 +503,7 @@
 impl<T: fmt::Debug> fmt::Debug for RwLockWriteGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("RwLockWriteGuard")
-            .field("lock", &self.__lock)
+            .field("lock", &self.lock)
             .finish()
     }
 }
@@ -520,7 +520,7 @@
     type Target = T;
 
     fn deref(&self) -> &T {
-        unsafe { &*self.__lock.data.get() }
+        unsafe { &*self.lock.data.get() }
     }
 }
 
@@ -529,29 +529,29 @@
     type Target = T;
 
     fn deref(&self) -> &T {
-        unsafe { &*self.__lock.data.get() }
+        unsafe { &*self.lock.data.get() }
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> DerefMut for RwLockWriteGuard<'_, T> {
     fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.__lock.data.get() }
+        unsafe { &mut *self.lock.data.get() }
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Drop for RwLockReadGuard<'_, T> {
     fn drop(&mut self) {
-        unsafe { self.__lock.inner.read_unlock(); }
+        unsafe { self.lock.inner.read_unlock(); }
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Drop for RwLockWriteGuard<'_, T> {
     fn drop(&mut self) {
-        self.__lock.poison.done(&self.__poison);
-        unsafe { self.__lock.inner.write_unlock(); }
+        self.lock.poison.done(&self.poison);
+        unsafe { self.lock.inner.write_unlock(); }
     }
 }
 
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 75ddf10..92ba071 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -2488,14 +2488,14 @@
 ///
 /// The name might be a dummy name in case of anonymous items.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub struct Item {
+pub struct Item<K = ItemKind> {
     pub attrs: Vec<Attribute>,
     pub id: NodeId,
     pub span: Span,
     pub vis: Visibility,
     pub ident: Ident,
 
-    pub kind: ItemKind,
+    pub kind: K,
 
     /// Original tokens this item was parsed from. This isn't necessarily
     /// available for all items, although over time more and more items should
@@ -2650,16 +2650,7 @@
     }
 }
 
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub struct ForeignItem {
-    pub attrs: Vec<Attribute>,
-    pub id: NodeId,
-    pub span: Span,
-    pub vis: Visibility,
-    pub ident: Ident,
-
-    pub kind: ForeignItemKind,
-}
+pub type ForeignItem = Item<ForeignItemKind>;
 
 /// An item within an `extern` block.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index a947426..3617380 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -7,6 +7,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/",
        test(attr(deny(warnings))))]
 
+#![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(const_fn)]
 #![feature(const_transmute)]
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index 8889e5d..f8795d8 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -1053,7 +1053,7 @@
 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
     -> SmallVec<[ForeignItem; 1]>
 {
-    let ForeignItem { ident, attrs, kind, id, span, vis } = &mut item;
+    let ForeignItem { ident, attrs, id, kind, vis, span, tokens: _ } = &mut item;
     visitor.visit_ident(ident);
     visit_attrs(attrs, visitor);
     match kind {
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 4821bbd..b2e8d85 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -317,7 +317,7 @@
 }
 
 fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String {
-    let convert_dollar_crate = if convert_dollar_crate { Some(token.span) } else { None };
+    let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
     token_kind_to_string_ext(&token.kind, convert_dollar_crate)
 }
 
diff --git a/src/libsyntax/util/lev_distance.rs b/src/libsyntax/util/lev_distance.rs
index 4127a8c..efb3c23 100644
--- a/src/libsyntax/util/lev_distance.rs
+++ b/src/libsyntax/util/lev_distance.rs
@@ -77,6 +77,6 @@
     if let Some(candidate) = case_insensitive_match {
         Some(candidate) // exact case insensitive match has a higher priority
     } else {
-        if let Some((candidate, _)) = levenstein_match { Some(candidate) } else { None }
+        levenstein_match.map(|(candidate, _)| candidate)
     }
 }
diff --git a/src/libsyntax_expand/placeholders.rs b/src/libsyntax_expand/placeholders.rs
index 74ade1d..faea04e 100644
--- a/src/libsyntax_expand/placeholders.rs
+++ b/src/libsyntax_expand/placeholders.rs
@@ -65,6 +65,7 @@
             AstFragment::ForeignItems(smallvec![ast::ForeignItem {
                 id, span, ident, vis, attrs,
                 kind: ast::ForeignItemKind::Macro(mac_placeholder()),
+                tokens: None,
             }]),
         AstFragmentKind::Pat => AstFragment::Pat(P(ast::Pat {
             id, span, kind: ast::PatKind::Mac(mac_placeholder()),
diff --git a/src/libsyntax_expand/proc_macro.rs b/src/libsyntax_expand/proc_macro.rs
index 8e56e2b..520488c 100644
--- a/src/libsyntax_expand/proc_macro.rs
+++ b/src/libsyntax_expand/proc_macro.rs
@@ -1,7 +1,7 @@
 use crate::base::{self, *};
 use crate::proc_macro_server;
 
-use syntax::ast::{self, ItemKind, MacArgs};
+use syntax::ast::{self, ItemKind, MetaItemKind, NestedMetaItem};
 use syntax::errors::{Applicability, FatalError};
 use syntax::symbol::sym;
 use syntax::token;
@@ -171,34 +171,71 @@
         if !attr.has_name(sym::derive) {
             return true;
         }
-        if !attr.is_meta_item_list() {
-            cx.struct_span_err(attr.span, "malformed `derive` attribute input")
-                .span_suggestion(
-                    attr.span,
-                    "missing traits to be derived",
-                    "#[derive(Trait1, Trait2, ...)]".to_owned(),
-                    Applicability::HasPlaceholders,
-                ).emit();
-            return false;
-        }
 
-        let parse_derive_paths = |attr: &ast::Attribute| {
-            if let MacArgs::Empty = attr.get_normal_item().args {
-                return Ok(Vec::new());
+        // 1) First let's ensure that it's a meta item.
+        let nmis = match attr.meta_item_list() {
+            None => {
+                cx.struct_span_err(attr.span, "malformed `derive` attribute input")
+                    .span_suggestion(
+                        attr.span,
+                        "missing traits to be derived",
+                        "#[derive(Trait1, Trait2, ...)]".to_owned(),
+                        Applicability::HasPlaceholders,
+                    )
+                    .emit();
+                return false;
             }
-            rustc_parse::parse_in_attr(cx.parse_sess, attr, |p| p.parse_derive_paths())
+            Some(x) => x,
         };
 
-        match parse_derive_paths(attr) {
-            Ok(traits) => {
-                result.extend(traits);
-                true
-            }
-            Err(mut e) => {
-                e.emit();
-                false
-            }
-        }
+        let mut error_reported_filter_map = false;
+        let mut error_reported_map = false;
+        let traits = nmis
+            .into_iter()
+            // 2) Moreover, let's ensure we have a path and not `#[derive("foo")]`.
+            .filter_map(|nmi| match nmi {
+                NestedMetaItem::Literal(lit) => {
+                    error_reported_filter_map = true;
+                    cx.struct_span_err(lit.span, "expected path to a trait, found literal")
+                        .help("for example, write `#[derive(Debug)]` for `Debug`")
+                        .emit();
+                    None
+                }
+                NestedMetaItem::MetaItem(mi) => Some(mi),
+            })
+            // 3) Finally, we only accept `#[derive($path_0, $path_1, ..)]`
+            // but not e.g. `#[derive($path_0 = "value", $path_1(abc))]`.
+            // In this case we can still at least determine that the user
+            // wanted this trait to be derived, so let's keep it.
+            .map(|mi| {
+                let mut traits_dont_accept = |title, action| {
+                    error_reported_map = true;
+                    let sp = mi.span.with_lo(mi.path.span.hi());
+                    cx.struct_span_err(sp, title)
+                        .span_suggestion(
+                            sp,
+                            action,
+                            String::new(),
+                            Applicability::MachineApplicable,
+                        )
+                        .emit();
+                };
+                match &mi.kind {
+                    MetaItemKind::List(..) => traits_dont_accept(
+                        "traits in `#[derive(...)]` don't accept arguments",
+                        "remove the arguments",
+                    ),
+                    MetaItemKind::NameValue(..) => traits_dont_accept(
+                        "traits in `#[derive(...)]` don't accept values",
+                        "remove the value",
+                    ),
+                    MetaItemKind::Word => {}
+                }
+                mi.path
+            });
+
+        result.extend(traits);
+        !error_reported_filter_map && !error_reported_map
     });
     result
 }
diff --git a/src/libsyntax_ext/format_foreign.rs b/src/libsyntax_ext/format_foreign.rs
index 3d4f827..0d1d292 100644
--- a/src/libsyntax_ext/format_foreign.rs
+++ b/src/libsyntax_ext/format_foreign.rs
@@ -95,12 +95,12 @@
             };
 
             // Has a special form in Rust for numbers.
-            let fill = if c_zero { Some("0") } else { None };
+            let fill = c_zero.then_some("0");
 
-            let align = if c_left { Some("<") } else { None };
+            let align = c_left.then_some("<");
 
             // Rust doesn't have an equivalent to the `' '` flag.
-            let sign = if c_plus { Some("+") } else { None };
+            let sign = c_plus.then_some("+");
 
             // Not *quite* the same, depending on the type...
             let alt = c_alt;
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index b9287d2..55c7f3f 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -3,6 +3,7 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
 #![feature(nll)]
diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs
index c68e03b..e8f7a12 100644
--- a/src/libsyntax_pos/symbol.rs
+++ b/src/libsyntax_pos/symbol.rs
@@ -213,6 +213,7 @@
         const_indexing,
         const_in_array_repeat_expressions,
         const_let,
+        const_mut_refs,
         const_panic,
         const_raw_ptr_deref,
         const_raw_ptr_to_usize_cast,
diff --git a/src/libtest/lib.rs b/src/libtest/lib.rs
index 7647978..0097558 100644
--- a/src/libtest/lib.rs
+++ b/src/libtest/lib.rs
@@ -24,6 +24,7 @@
 #![cfg_attr(any(unix, target_os = "cloudabi"), feature(libc))]
 #![feature(rustc_private)]
 #![feature(nll)]
+#![feature(bool_to_option)]
 #![feature(set_stdio)]
 #![feature(panic_unwind)]
 #![feature(staged_api)]
@@ -562,11 +563,7 @@
         None
     };
 
-    let start = if report_time {
-        Some(Instant::now())
-    } else {
-        None
-    };
+    let start = report_time.then(Instant::now);
     let result = catch_unwind(AssertUnwindSafe(testfn));
     let exec_time = start.map(|start| {
         let duration = start.elapsed();
@@ -597,11 +594,7 @@
         let args = env::args().collect::<Vec<_>>();
         let current_exe = &args[0];
 
-        let start = if report_time {
-            Some(Instant::now())
-        } else {
-            None
-        };
+        let start = report_time.then(Instant::now);
         let output = match Command::new(current_exe)
             .env(SECONDARY_TEST_INVOKER_VAR, desc.name.as_slice())
             .output() {
diff --git a/src/llvm-project b/src/llvm-project
index de1a7db..2cb4100 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit de1a7dbf6c6b34f56e65732d45970ff27a8e84bf
+Subproject commit 2cb41005ed5c4747b10d2bf01d8779d3bb4ae32d
diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index a83ba9a..720928e 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -129,8 +129,9 @@
 }
 
 extern "C" LLVMValueRef
-LLVMRustGetOrInsertGlobal(LLVMModuleRef M, const char *Name, LLVMTypeRef Ty) {
-  return wrap(unwrap(M)->getOrInsertGlobal(Name, unwrap(Ty)));
+LLVMRustGetOrInsertGlobal(LLVMModuleRef M, const char *Name, size_t NameLen, LLVMTypeRef Ty) {
+  StringRef NameRef(Name, NameLen);
+  return wrap(unwrap(M)->getOrInsertGlobal(NameRef, unwrap(Ty)));
 }
 
 extern "C" LLVMValueRef
@@ -1287,11 +1288,12 @@
 }
 
 extern "C" void LLVMRustSetComdat(LLVMModuleRef M, LLVMValueRef V,
-                                  const char *Name) {
+                                  const char *Name, size_t NameLen) {
   Triple TargetTriple(unwrap(M)->getTargetTriple());
   GlobalObject *GV = unwrap<GlobalObject>(V);
   if (!TargetTriple.isOSBinFormatMachO()) {
-    GV->setComdat(unwrap(M)->getOrInsertComdat(Name));
+    StringRef NameRef(Name, NameLen);
+    GV->setComdat(unwrap(M)->getOrInsertComdat(NameRef));
   }
 }
 
diff --git a/src/test/codegen/set-discriminant-invalid.rs b/src/test/codegen/set-discriminant-invalid.rs
new file mode 100644
index 0000000..d9614f0
--- /dev/null
+++ b/src/test/codegen/set-discriminant-invalid.rs
@@ -0,0 +1,43 @@
+// compile-flags: -C opt-level=0
+#![crate_type = "lib"]
+
+pub enum ApiError {}
+#[allow(dead_code)]
+pub struct TokioError {
+    b: bool,
+}
+pub enum Error {
+    Api {
+        source: ApiError,
+    },
+    Ethereum,
+    Tokio {
+        source: TokioError,
+    },
+}
+struct Api;
+impl IntoError<Error> for Api
+{
+    type Source = ApiError;
+    // CHECK-LABEL: @into_error
+    // CHECK: llvm.trap()
+    // Also check the next two instructions to make sure we do not match against `trap`
+    // elsewhere in the code.
+    // CHECK-NEXT: load
+    // CHECK-NEXT: ret
+    #[no_mangle]
+    fn into_error(self, error: Self::Source) -> Error {
+        Error::Api {
+            source: (|v| v)(error),
+        }
+    }
+}
+
+pub trait IntoError<E>
+{
+    /// The underlying error
+    type Source;
+
+    /// Combine the information to produce the error
+    fn into_error(self, source: Self::Source) -> E;
+}
diff --git a/src/test/compile-fail/consts/const-err3.rs b/src/test/compile-fail/consts/const-err3.rs
index add4eef..fc10824 100644
--- a/src/test/compile-fail/consts/const-err3.rs
+++ b/src/test/compile-fail/consts/const-err3.rs
@@ -14,7 +14,6 @@
     //~^ ERROR const_err
     let _e = [5u8][1];
     //~^ ERROR const_err
-    //~| ERROR this expression will panic at runtime
     black_box(b);
     black_box(c);
     black_box(d);
diff --git a/src/test/compile-fail/consts/const-fn-error.rs b/src/test/compile-fail/consts/const-fn-error.rs
index 1a4fc72..5d26059 100644
--- a/src/test/compile-fail/consts/const-fn-error.rs
+++ b/src/test/compile-fail/consts/const-fn-error.rs
@@ -6,7 +6,7 @@
     let mut sum = 0;
     for i in 0..x {
         //~^ ERROR E0015
-        //~| ERROR E0017
+        //~| ERROR E0658
         //~| ERROR E0080
         //~| ERROR E0744
         //~| ERROR E0019
diff --git a/src/test/incremental/issue-61323.rs b/src/test/incremental/issue-61323.rs
new file mode 100644
index 0000000..448ce36
--- /dev/null
+++ b/src/test/incremental/issue-61323.rs
@@ -0,0 +1,15 @@
+// revisions: rpass cfail
+
+enum A {
+    //[cfail]~^ ERROR 3:1: 3:7: recursive type `A` has infinite size [E0072]
+    B(C),
+}
+
+#[cfg(rpass)]
+struct C(Box<A>);
+
+#[cfg(cfail)]
+struct C(A);
+//[cfail]~^ ERROR 12:1: 12:13: recursive type `C` has infinite size [E0072]
+
+fn main() {}
diff --git a/src/test/rustdoc-ui/issue-61732.rs b/src/test/rustdoc-ui/issue-61732.rs
new file mode 100644
index 0000000..d4835c0
--- /dev/null
+++ b/src/test/rustdoc-ui/issue-61732.rs
@@ -0,0 +1,4 @@
+// This previously triggered an ICE.
+
+pub(in crate::r#mod) fn main() {}
+//~^ ERROR expected module, found unresolved item
diff --git a/src/test/rustdoc-ui/issue-61732.stderr b/src/test/rustdoc-ui/issue-61732.stderr
new file mode 100644
index 0000000..6c8ba48
--- /dev/null
+++ b/src/test/rustdoc-ui/issue-61732.stderr
@@ -0,0 +1,11 @@
+error[E0577]: expected module, found unresolved item `crate::r#mod`
+  --> $DIR/issue-61732.rs:3:8
+   |
+LL | pub(in crate::r#mod) fn main() {}
+   |        ^^^^^^^^^^^^ not a module
+
+error: Compilation failed, aborting rustdoc
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0577`.
diff --git a/src/test/rustdoc/duplicate-cfg.rs b/src/test/rustdoc/duplicate-cfg.rs
new file mode 100644
index 0000000..505d6ee
--- /dev/null
+++ b/src/test/rustdoc/duplicate-cfg.rs
@@ -0,0 +1,15 @@
+#![crate_name = "foo"]
+#![feature(doc_cfg)]
+
+// @has 'foo/index.html'
+// @!has '-' '//*[@class="stab portability"]' 'feature="sync" and'
+// @has '-' '//*[@class="stab portability"]' 'feature="sync"'
+#[doc(cfg(feature = "sync"))]
+#[doc(cfg(feature = "sync"))]
+pub struct Foo;
+
+#[doc(cfg(feature = "sync"))]
+pub mod bar {
+    #[doc(cfg(feature = "sync"))]
+    pub struct Bar;
+}
diff --git a/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.rs b/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.rs
new file mode 100644
index 0000000..c8c2702
--- /dev/null
+++ b/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.rs
@@ -0,0 +1,15 @@
+// edition:2018
+
+struct Ia<S>(S);
+
+impl<S> Ia<S> {
+    fn partial(_: S) {}
+    fn full(self) {}
+
+    async fn crash(self) {
+        Self::partial(self.0);
+        Self::full(self); //~ ERROR use of moved value: `self`
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.stderr b/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.stderr
new file mode 100644
index 0000000..9177b83
--- /dev/null
+++ b/src/test/ui/async-await/issues/issue-66958-non-copy-infered-type-arg.stderr
@@ -0,0 +1,13 @@
+error[E0382]: use of moved value: `self`
+  --> $DIR/issue-66958-non-copy-infered-type-arg.rs:11:20
+   |
+LL |         Self::partial(self.0);
+   |                       ------ value moved here
+LL |         Self::full(self);
+   |                    ^^^^ value used here after partial move
+   |
+   = note: move occurs because `self.0` has type `S`, which does not implement the `Copy` trait
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0382`.
diff --git a/src/test/ui/async-await/suggest-missing-await.fixed b/src/test/ui/async-await/suggest-missing-await.fixed
index 7c02a90..1ec59d9 100644
--- a/src/test/ui/async-await/suggest-missing-await.fixed
+++ b/src/test/ui/async-await/suggest-missing-await.fixed
@@ -16,4 +16,15 @@
     //~| SUGGESTION x.await
 }
 
+async fn dummy() {}
+
+#[allow(unused)]
+async fn suggest_await_in_async_fn_return() {
+    dummy().await;
+    //~^ ERROR mismatched types [E0308]
+    //~| HELP try adding a semicolon
+    //~| HELP consider using `.await` here
+    //~| SUGGESTION dummy().await
+}
+
 fn main() {}
diff --git a/src/test/ui/async-await/suggest-missing-await.rs b/src/test/ui/async-await/suggest-missing-await.rs
index 91abd44..70cc1f1 100644
--- a/src/test/ui/async-await/suggest-missing-await.rs
+++ b/src/test/ui/async-await/suggest-missing-await.rs
@@ -16,4 +16,15 @@
     //~| SUGGESTION x.await
 }
 
+async fn dummy() {}
+
+#[allow(unused)]
+async fn suggest_await_in_async_fn_return() {
+    dummy()
+    //~^ ERROR mismatched types [E0308]
+    //~| HELP try adding a semicolon
+    //~| HELP consider using `.await` here
+    //~| SUGGESTION dummy().await
+}
+
 fn main() {}
diff --git a/src/test/ui/async-await/suggest-missing-await.stderr b/src/test/ui/async-await/suggest-missing-await.stderr
index 7a635a3..7ab0244 100644
--- a/src/test/ui/async-await/suggest-missing-await.stderr
+++ b/src/test/ui/async-await/suggest-missing-await.stderr
@@ -10,6 +10,23 @@
    = note:     expected type `u32`
            found opaque type `impl std::future::Future`
 
-error: aborting due to previous error
+error[E0308]: mismatched types
+  --> $DIR/suggest-missing-await.rs:23:5
+   |
+LL |     dummy()
+   |     ^^^^^^^ expected `()`, found opaque type
+   |
+   = note: expected unit type `()`
+            found opaque type `impl std::future::Future`
+help: try adding a semicolon
+   |
+LL |     dummy();
+   |            ^
+help: consider using `.await` here
+   |
+LL |     dummy().await
+   |
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/check-static-immutable-mut-slices.stderr b/src/test/ui/check-static-immutable-mut-slices.stderr
index 4f4bf16..39da824 100644
--- a/src/test/ui/check-static-immutable-mut-slices.stderr
+++ b/src/test/ui/check-static-immutable-mut-slices.stderr
@@ -1,9 +1,12 @@
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/check-static-immutable-mut-slices.rs:3:37
    |
 LL | static TEST: &'static mut [isize] = &mut [];
    |                                     ^^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0017`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/closures/closure-expected-type/expect-region-supply-region.polonius.stderr b/src/test/ui/closures/closure-expected-type/expect-region-supply-region.polonius.stderr
new file mode 100644
index 0000000..2a7461f
--- /dev/null
+++ b/src/test/ui/closures/closure-expected-type/expect-region-supply-region.polonius.stderr
@@ -0,0 +1,56 @@
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/expect-region-supply-region.rs:18:9
+   |
+LL |     let mut f: Option<&u32> = None;
+   |         ----- `f` is declared here, outside of the closure body
+LL |     closure_expecting_bound(|x| {
+   |                              - `x` is a reference that is only valid in the closure body
+LL |         f = Some(x);
+   |         ^^^^^^^^^^^ `x` escapes the closure body here
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/expect-region-supply-region.rs:28:9
+   |
+LL |     let mut f: Option<&u32> = None;
+   |         ----- `f` is declared here, outside of the closure body
+LL |     closure_expecting_bound(|x: &u32| {
+   |                              - `x` is a reference that is only valid in the closure body
+LL |         f = Some(x);
+   |         ^^^^^^^^^^^ `x` escapes the closure body here
+
+error: lifetime may not live long enough
+  --> $DIR/expect-region-supply-region.rs:37:30
+   |
+LL | fn expect_bound_supply_named<'x>() {
+   |                              -- lifetime `'x` defined here
+...
+LL |     closure_expecting_bound(|x: &'x u32| {
+   |                              ^  - let's call the lifetime of this reference `'1`
+   |                              |
+   |                              requires that `'1` must outlive `'x`
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/expect-region-supply-region.rs:42:9
+   |
+LL |     let mut f: Option<&u32> = None;
+   |         ----- `f` is declared here, outside of the closure body
+...
+LL |     closure_expecting_bound(|x: &'x u32| {
+   |                              - `x` is a reference that is only valid in the closure body
+...
+LL |         f = Some(x);
+   |         ^^^^^^^^^^^ `x` escapes the closure body here
+
+error: lifetime may not live long enough
+  --> $DIR/expect-region-supply-region.rs:37:30
+   |
+LL | fn expect_bound_supply_named<'x>() {
+   |                              -- lifetime `'x` defined here
+...
+LL |     closure_expecting_bound(|x: &'x u32| {
+   |                              ^ requires that `'x` must outlive `'static`
+   |
+   = help: consider replacing `'x` with `'static`
+
+error: aborting due to 5 previous errors
+
diff --git a/src/test/ui/conditional-compilation/cfg-attr-parse.rs b/src/test/ui/conditional-compilation/cfg-attr-parse.rs
index 93aef72..8ca31c1 100644
--- a/src/test/ui/conditional-compilation/cfg-attr-parse.rs
+++ b/src/test/ui/conditional-compilation/cfg-attr-parse.rs
@@ -1,11 +1,11 @@
 // Parse `cfg_attr` with varying numbers of attributes and trailing commas
 
 // Completely empty `cfg_attr` input
-#[cfg_attr()] //~ error: expected identifier, found `)`
+#[cfg_attr()] //~ error: malformed `cfg_attr` attribute input
 struct NoConfigurationPredicate;
 
 // Zero attributes, zero trailing comma (comma manatory here)
-#[cfg_attr(all())] //~ error: expected `,`, found `)`
+#[cfg_attr(all())] //~ error: expected `,`, found end of `cfg_attr`
 struct A0C0;
 
 // Zero attributes, one trailing comma
@@ -40,4 +40,16 @@
 #[cfg_attr(all(), must_use, deprecated,,)] //~ ERROR expected identifier
 struct A2C2;
 
+// Wrong delimiter `[`
+#[cfg_attr[all(),,]]
+//~^ ERROR wrong `cfg_attr` delimiters
+//~| ERROR expected identifier, found `,`
+struct BracketZero;
+
+// Wrong delimiter `{`
+#[cfg_attr{all(),,}]
+//~^ ERROR wrong `cfg_attr` delimiters
+//~| ERROR expected identifier, found `,`
+struct BraceZero;
+
 fn main() {}
diff --git a/src/test/ui/conditional-compilation/cfg-attr-parse.stderr b/src/test/ui/conditional-compilation/cfg-attr-parse.stderr
index 3dfbd6d..3a590d3 100644
--- a/src/test/ui/conditional-compilation/cfg-attr-parse.stderr
+++ b/src/test/ui/conditional-compilation/cfg-attr-parse.stderr
@@ -1,32 +1,86 @@
-error: expected identifier, found `)`
-  --> $DIR/cfg-attr-parse.rs:4:12
+error: malformed `cfg_attr` attribute input
+  --> $DIR/cfg-attr-parse.rs:4:1
    |
 LL | #[cfg_attr()]
-   |            ^ expected identifier
+   | ^^^^^^^^^^^^^ help: missing condition and attribute: `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
-error: expected `,`, found `)`
+error: expected `,`, found end of `cfg_attr` input
   --> $DIR/cfg-attr-parse.rs:8:17
    |
 LL | #[cfg_attr(all())]
    |                 ^ expected `,`
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error: expected identifier, found `,`
   --> $DIR/cfg-attr-parse.rs:16:18
    |
 LL | #[cfg_attr(all(),,)]
    |                  ^ expected identifier
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error: expected identifier, found `,`
   --> $DIR/cfg-attr-parse.rs:28:28
    |
 LL | #[cfg_attr(all(), must_use,,)]
    |                            ^ expected identifier
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error: expected identifier, found `,`
   --> $DIR/cfg-attr-parse.rs:40:40
    |
 LL | #[cfg_attr(all(), must_use, deprecated,,)]
    |                                        ^ expected identifier
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
-error: aborting due to 5 previous errors
+error: wrong `cfg_attr` delimiters
+  --> $DIR/cfg-attr-parse.rs:44:11
+   |
+LL | #[cfg_attr[all(),,]]
+   |           ^^^^^^^^^
+   |
+help: the delimiters should be `(` and `)`
+   |
+LL | #[cfg_attr(all(),,)]
+   |           ^       ^
+
+error: expected identifier, found `,`
+  --> $DIR/cfg-attr-parse.rs:44:18
+   |
+LL | #[cfg_attr[all(),,]]
+   |                  ^ expected identifier
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
+
+error: wrong `cfg_attr` delimiters
+  --> $DIR/cfg-attr-parse.rs:50:11
+   |
+LL | #[cfg_attr{all(),,}]
+   |           ^^^^^^^^^
+   |
+help: the delimiters should be `(` and `)`
+   |
+LL | #[cfg_attr(all(),,)]
+   |           ^       ^
+
+error: expected identifier, found `,`
+  --> $DIR/cfg-attr-parse.rs:50:18
+   |
+LL | #[cfg_attr{all(),,}]
+   |                  ^ expected identifier
+   |
+   = help: the valid syntax is `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
+
+error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/consts/array-literal-index-oob.stderr b/src/test/ui/consts/array-literal-index-oob.stderr
index 0ddc2a0..f4d4e6f 100644
--- a/src/test/ui/consts/array-literal-index-oob.stderr
+++ b/src/test/ui/consts/array-literal-index-oob.stderr
@@ -12,7 +12,7 @@
 LL |     &{[1, 2, 3][4]};
    |     --^^^^^^^^^^^^-
    |       |
-   |       index out of bounds: the len is 3 but the index is 4
+   |       indexing out of bounds: the len is 3 but the index is 4
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/consts/const-err2.rs b/src/test/ui/consts/const-err2.rs
index e5ee90f..ecbcc2a 100644
--- a/src/test/ui/consts/const-err2.rs
+++ b/src/test/ui/consts/const-err2.rs
@@ -23,7 +23,6 @@
     //~^ ERROR const_err
     let _e = [5u8][1];
     //~^ ERROR index out of bounds
-    //~| ERROR this expression will panic at runtime
     black_box(a);
     black_box(b);
     black_box(c);
diff --git a/src/test/ui/consts/const-err2.stderr b/src/test/ui/consts/const-err2.stderr
index 0a09a72..1d84d44 100644
--- a/src/test/ui/consts/const-err2.stderr
+++ b/src/test/ui/consts/const-err2.stderr
@@ -34,11 +34,5 @@
 LL |     let _e = [5u8][1];
    |              ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:24:14
-   |
-LL |     let _e = [5u8][1];
-   |              ^^^^^^^^ index out of bounds: the len is 1 but the index is 1
-
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/consts/const-err3.rs b/src/test/ui/consts/const-err3.rs
index 89373f9..a9cf04c 100644
--- a/src/test/ui/consts/const-err3.rs
+++ b/src/test/ui/consts/const-err3.rs
@@ -23,7 +23,6 @@
     //~^ ERROR const_err
     let _e = [5u8][1];
     //~^ ERROR const_err
-    //~| ERROR this expression will panic at runtime
     black_box(a);
     black_box(b);
     black_box(c);
diff --git a/src/test/ui/consts/const-err3.stderr b/src/test/ui/consts/const-err3.stderr
index 42de247..0602707 100644
--- a/src/test/ui/consts/const-err3.stderr
+++ b/src/test/ui/consts/const-err3.stderr
@@ -34,11 +34,5 @@
 LL |     let _e = [5u8][1];
    |              ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/const-err3.rs:24:14
-   |
-LL |     let _e = [5u8][1];
-   |              ^^^^^^^^ index out of bounds: the len is 1 but the index is 1
-
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/consts/const-eval/const_caller_location.rs b/src/test/ui/consts/const-eval/const_caller_location.rs
deleted file mode 100644
index c63822f..0000000
--- a/src/test/ui/consts/const-eval/const_caller_location.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-// run-pass
-
-#![feature(const_fn, core_intrinsics)]
-
-use std::{intrinsics::caller_location, panic::Location};
-
-const LOCATION: &Location = caller_location();
-const NESTED: &Location = {
-    const fn nested_location() -> &'static Location<'static> {
-        caller_location()
-    };
-    nested_location()
-};
-
-fn main() {
-    assert_eq!(LOCATION.file(), file!());
-    assert_eq!(LOCATION.line(), 7);
-    assert_eq!(LOCATION.column(), 29);
-
-    assert_eq!(NESTED.file(), file!());
-    assert_eq!(NESTED.line(), 10);
-    assert_eq!(NESTED.column(), 9);
-}
diff --git a/src/test/ui/consts/const-eval/issue-65394.stderr b/src/test/ui/consts/const-eval/issue-65394.stderr
index acf5cba..54b3507 100644
--- a/src/test/ui/consts/const-eval/issue-65394.stderr
+++ b/src/test/ui/consts/const-eval/issue-65394.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/issue-65394.rs:8:13
    |
 LL |     let r = &mut x;
    |             ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0493]: destructors cannot be evaluated at compile-time
   --> $DIR/issue-65394.rs:7:9
@@ -12,5 +15,5 @@
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0017, E0493.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0493, E0658.
+For more information about an error, try `rustc --explain E0493`.
diff --git a/src/test/ui/consts/const-eval/promoted_errors.rs b/src/test/ui/consts/const-eval/promoted_errors.rs
index 4594139..dfa6863 100644
--- a/src/test/ui/consts/const-eval/promoted_errors.rs
+++ b/src/test/ui/consts/const-eval/promoted_errors.rs
@@ -8,14 +8,12 @@
     //~^ ERROR const_err
     println!("{}", 1/(1-1));
     //~^ ERROR attempt to divide by zero [const_err]
-    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    //~| ERROR const_err
     let _x = 1/(1-1);
     //~^ ERROR const_err
-    //~| ERROR const_err
     println!("{}", 1/(false as u32));
     //~^ ERROR attempt to divide by zero [const_err]
-    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    //~| ERROR const_err
     let _x = 1/(false as u32);
     //~^ ERROR const_err
-    //~| ERROR const_err
 }
diff --git a/src/test/ui/consts/const-eval/promoted_errors.stderr b/src/test/ui/consts/const-eval/promoted_errors.stderr
index 40d5c73..848a880 100644
--- a/src/test/ui/consts/const-eval/promoted_errors.stderr
+++ b/src/test/ui/consts/const-eval/promoted_errors.stderr
@@ -20,7 +20,7 @@
   --> $DIR/promoted_errors.rs:9:20
    |
 LL |     println!("{}", 1/(1-1));
-   |                    ^^^^^^^ attempt to divide by zero
+   |                    ^^^^^^^ dividing by zero
 
 error: attempt to divide by zero
   --> $DIR/promoted_errors.rs:12:14
@@ -28,35 +28,23 @@
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:12:14
-   |
-LL |     let _x = 1/(1-1);
-   |              ^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:15:20
+  --> $DIR/promoted_errors.rs:14:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^
 
 error: reaching this expression at runtime will panic or abort
-  --> $DIR/promoted_errors.rs:15:20
+  --> $DIR/promoted_errors.rs:14:20
    |
 LL |     println!("{}", 1/(false as u32));
-   |                    ^^^^^^^^^^^^^^^^ attempt to divide by zero
+   |                    ^^^^^^^^^^^^^^^^ dividing by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:18:14
+  --> $DIR/promoted_errors.rs:17:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:18:14
-   |
-LL |     let _x = 1/(false as u32);
-   |              ^^^^^^^^^^^^^^^^ attempt to divide by zero
-
-error: aborting due to 9 previous errors
+error: aborting due to 7 previous errors
 
diff --git a/src/test/ui/consts/const-eval/promoted_errors2.rs b/src/test/ui/consts/const-eval/promoted_errors2.rs
index 7adb394..58b1794 100644
--- a/src/test/ui/consts/const-eval/promoted_errors2.rs
+++ b/src/test/ui/consts/const-eval/promoted_errors2.rs
@@ -9,14 +9,12 @@
     //~^ ERROR attempt to subtract with overflow
     println!("{}", 1/(1-1));
     //~^ ERROR attempt to divide by zero [const_err]
-    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    //~| ERROR const_err
     let _x = 1/(1-1);
     //~^ ERROR const_err
-    //~| ERROR const_err
     println!("{}", 1/(false as u32));
     //~^ ERROR attempt to divide by zero [const_err]
-    //~| ERROR reaching this expression at runtime will panic or abort [const_err]
+    //~| ERROR const_err
     let _x = 1/(false as u32);
     //~^ ERROR const_err
-    //~| ERROR const_err
 }
diff --git a/src/test/ui/consts/const-eval/promoted_errors2.stderr b/src/test/ui/consts/const-eval/promoted_errors2.stderr
index 2819e6e..6f4b1c0 100644
--- a/src/test/ui/consts/const-eval/promoted_errors2.stderr
+++ b/src/test/ui/consts/const-eval/promoted_errors2.stderr
@@ -26,7 +26,7 @@
   --> $DIR/promoted_errors2.rs:10:20
    |
 LL |     println!("{}", 1/(1-1));
-   |                    ^^^^^^^ attempt to divide by zero
+   |                    ^^^^^^^ dividing by zero
 
 error: attempt to divide by zero
   --> $DIR/promoted_errors2.rs:13:14
@@ -34,35 +34,23 @@
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/promoted_errors2.rs:13:14
-   |
-LL |     let _x = 1/(1-1);
-   |              ^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/promoted_errors2.rs:16:20
+  --> $DIR/promoted_errors2.rs:15:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^
 
 error: reaching this expression at runtime will panic or abort
-  --> $DIR/promoted_errors2.rs:16:20
+  --> $DIR/promoted_errors2.rs:15:20
    |
 LL |     println!("{}", 1/(false as u32));
-   |                    ^^^^^^^^^^^^^^^^ attempt to divide by zero
+   |                    ^^^^^^^^^^^^^^^^ dividing by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors2.rs:19:14
+  --> $DIR/promoted_errors2.rs:18:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/promoted_errors2.rs:19:14
-   |
-LL |     let _x = 1/(false as u32);
-   |              ^^^^^^^^^^^^^^^^ attempt to divide by zero
-
-error: aborting due to 10 previous errors
+error: aborting due to 8 previous errors
 
diff --git a/src/test/ui/consts/const-multi-ref.stderr b/src/test/ui/consts/const-multi-ref.stderr
index ed3837e..0809c77 100644
--- a/src/test/ui/consts/const-multi-ref.stderr
+++ b/src/test/ui/consts/const-multi-ref.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/const-multi-ref.rs:6:13
    |
 LL |     let p = &mut a;
    |             ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
   --> $DIR/const-multi-ref.rs:16:13
@@ -12,5 +15,5 @@
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0017, E0492.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0492, E0658.
+For more information about an error, try `rustc --explain E0492`.
diff --git a/src/test/ui/consts/const-mut-refs/const_mut_refs.rs b/src/test/ui/consts/const-mut-refs/const_mut_refs.rs
new file mode 100644
index 0000000..99006a2
--- /dev/null
+++ b/src/test/ui/consts/const-mut-refs/const_mut_refs.rs
@@ -0,0 +1,36 @@
+// run-pass
+
+#![feature(const_mut_refs)]
+
+struct Foo {
+    x: usize
+}
+
+const fn foo() -> Foo {
+    Foo { x: 0 }
+}
+
+impl Foo {
+    const fn bar(&mut self) -> usize {
+        self.x = 1;
+        self.x
+    }
+
+}
+
+const fn baz(foo: &mut Foo) -> usize {
+    let x = &mut foo.x;
+    *x = 2;
+    *x
+}
+
+const fn bazz(foo: &mut Foo) -> usize {
+    foo.x = 3;
+    foo.x
+}
+
+fn main() {
+    let _: [(); foo().bar()] = [(); 1];
+    let _: [(); baz(&mut foo())] = [(); 2];
+    let _: [(); bazz(&mut foo())] = [(); 3];
+}
diff --git a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs
new file mode 100644
index 0000000..2207599
--- /dev/null
+++ b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs
@@ -0,0 +1,7 @@
+fn main() {
+    foo(&mut 5);
+}
+
+const fn foo(x: &mut i32) -> i32 { //~ ERROR mutable references in const fn are unstable
+    *x + 1
+}
diff --git a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr
new file mode 100644
index 0000000..4fae119
--- /dev/null
+++ b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr
@@ -0,0 +1,12 @@
+error[E0723]: mutable references in const fn are unstable
+  --> $DIR/feature-gate-const_mut_refs.rs:5:14
+   |
+LL | const fn foo(x: &mut i32) -> i32 {
+   |              ^
+   |
+   = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
+   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0723`.
diff --git a/src/test/ui/consts/const-prop-ice.rs b/src/test/ui/consts/const-prop-ice.rs
index 48c4b7d..13309f9 100644
--- a/src/test/ui/consts/const-prop-ice.rs
+++ b/src/test/ui/consts/const-prop-ice.rs
@@ -1,4 +1,3 @@
 fn main() {
     [0; 3][3u64 as usize]; //~ ERROR the len is 3 but the index is 3
-    //~| ERROR this expression will panic at runtime
 }
diff --git a/src/test/ui/consts/const-prop-ice.stderr b/src/test/ui/consts/const-prop-ice.stderr
index 8ecc6f4..4b38801 100644
--- a/src/test/ui/consts/const-prop-ice.stderr
+++ b/src/test/ui/consts/const-prop-ice.stderr
@@ -6,11 +6,5 @@
    |
    = note: `#[deny(const_err)]` on by default
 
-error: this expression will panic at runtime
-  --> $DIR/const-prop-ice.rs:2:5
-   |
-LL |     [0; 3][3u64 as usize];
-   |     ^^^^^^^^^^^^^^^^^^^^^ index out of bounds: the len is 3 but the index is 3
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
diff --git a/src/test/ui/consts/const_let_assign3.stderr b/src/test/ui/consts/const_let_assign3.stderr
index 53b960b..7852874 100644
--- a/src/test/ui/consts/const_let_assign3.stderr
+++ b/src/test/ui/consts/const_let_assign3.stderr
@@ -4,17 +4,23 @@
 LL |         self.state = x;
    |         ^^^^^^^^^^^^^^
 
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/const_let_assign3.rs:16:5
    |
 LL |     s.foo(3);
    |     ^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/const_let_assign3.rs:22:13
    |
 LL |     let y = &mut x;
    |             ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0019]: constant contains unimplemented expression type
   --> $DIR/const_let_assign3.rs:24:5
@@ -24,5 +30,5 @@
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0017, E0019.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0019, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/consts/miri_unleashed/mutable_const.rs b/src/test/ui/consts/miri_unleashed/mutable_const.rs
index 44b4084..972f595 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_const.rs
+++ b/src/test/ui/consts/miri_unleashed/mutable_const.rs
@@ -1,6 +1,7 @@
 // compile-flags: -Zunleash-the-miri-inside-of-you
 
 #![feature(const_raw_ptr_deref)]
+#![feature(const_mut_refs)]
 #![deny(const_err)]
 
 use std::cell::UnsafeCell;
@@ -12,9 +13,7 @@
 const MUTATING_BEHIND_RAW: () = {
     // Test that `MUTABLE_BEHIND_RAW` is actually immutable, by doing this at const time.
     unsafe {
-        *MUTABLE_BEHIND_RAW = 99 //~ WARN skipping const checks
-        //~^ ERROR any use of this value will cause an error
-        //~^^ tried to modify constant memory
+        *MUTABLE_BEHIND_RAW = 99 //~ ERROR any use of this value will cause an error
     }
 };
 
diff --git a/src/test/ui/consts/miri_unleashed/mutable_const.stderr b/src/test/ui/consts/miri_unleashed/mutable_const.stderr
index 757f0ff..9daca76 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_const.stderr
+++ b/src/test/ui/consts/miri_unleashed/mutable_const.stderr
@@ -1,30 +1,23 @@
 warning: skipping const checks
-  --> $DIR/mutable_const.rs:9:38
+  --> $DIR/mutable_const.rs:10:38
    |
 LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _;
    |                                      ^^^^^^^^^^^^^^^^^^^^
 
-warning: skipping const checks
-  --> $DIR/mutable_const.rs:15:9
-   |
-LL |         *MUTABLE_BEHIND_RAW = 99
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^
-
 error: any use of this value will cause an error
-  --> $DIR/mutable_const.rs:15:9
+  --> $DIR/mutable_const.rs:16:9
    |
 LL | / const MUTATING_BEHIND_RAW: () = {
 LL | |     // Test that `MUTABLE_BEHIND_RAW` is actually immutable, by doing this at const time.
 LL | |     unsafe {
 LL | |         *MUTABLE_BEHIND_RAW = 99
    | |         ^^^^^^^^^^^^^^^^^^^^^^^^ tried to modify constant memory
-...  |
 LL | |     }
 LL | | };
    | |__-
    |
 note: lint level defined here
-  --> $DIR/mutable_const.rs:4:9
+  --> $DIR/mutable_const.rs:5:9
    |
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
diff --git a/src/test/ui/consts/miri_unleashed/mutable_references.rs b/src/test/ui/consts/miri_unleashed/mutable_references.rs
index 59dafcb..fe3c4ee 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_references.rs
+++ b/src/test/ui/consts/miri_unleashed/mutable_references.rs
@@ -1,20 +1,22 @@
 // compile-flags: -Zunleash-the-miri-inside-of-you
+#![feature(const_mut_refs)]
 #![allow(const_err)]
 
 use std::cell::UnsafeCell;
 
 // a test demonstrating what things we could allow with a smarter const qualification
 
+// this is fine because is not possible to mutate through an immutable reference.
 static FOO: &&mut u32 = &&mut 42;
-//~^ WARN: skipping const checks
 
+// this is fine because accessing an immutable static `BAR` is equivalent to accessing `*&BAR`
+// which puts the mutable reference behind an immutable one.
 static BAR: &mut () = &mut ();
-//~^ WARN: skipping const checks
 
 struct Foo<T>(T);
 
+// this is fine for the same reason as `BAR`.
 static BOO: &mut Foo<()> = &mut Foo(());
-//~^ WARN: skipping const checks
 
 struct Meh {
     x: &'static UnsafeCell<i32>,
@@ -27,8 +29,8 @@
     //~^ WARN: skipping const checks
 };
 
+// this is fine for the same reason as `BAR`.
 static OH_YES: &mut i32 = &mut 42;
-//~^ WARN: skipping const checks
 
 fn main() {
     unsafe {
diff --git a/src/test/ui/consts/miri_unleashed/mutable_references.stderr b/src/test/ui/consts/miri_unleashed/mutable_references.stderr
index b9c0af3..3e1300c 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_references.stderr
+++ b/src/test/ui/consts/miri_unleashed/mutable_references.stderr
@@ -1,35 +1,11 @@
 warning: skipping const checks
-  --> $DIR/mutable_references.rs:8:26
-   |
-LL | static FOO: &&mut u32 = &&mut 42;
-   |                          ^^^^^^^
-
-warning: skipping const checks
-  --> $DIR/mutable_references.rs:11:23
-   |
-LL | static BAR: &mut () = &mut ();
-   |                       ^^^^^^^
-
-warning: skipping const checks
-  --> $DIR/mutable_references.rs:16:28
-   |
-LL | static BOO: &mut Foo<()> = &mut Foo(());
-   |                            ^^^^^^^^^^^^
-
-warning: skipping const checks
-  --> $DIR/mutable_references.rs:26:8
+  --> $DIR/mutable_references.rs:28:8
    |
 LL |     x: &UnsafeCell::new(42),
    |        ^^^^^^^^^^^^^^^^^^^^
 
-warning: skipping const checks
-  --> $DIR/mutable_references.rs:30:27
-   |
-LL | static OH_YES: &mut i32 = &mut 42;
-   |                           ^^^^^^^
-
 error[E0594]: cannot assign to `*OH_YES`, as `OH_YES` is an immutable static item
-  --> $DIR/mutable_references.rs:37:5
+  --> $DIR/mutable_references.rs:39:5
    |
 LL |     *OH_YES = 99;
    |     ^^^^^^^^^^^^ cannot assign
diff --git a/src/test/ui/consts/miri_unleashed/read_from_static.rs b/src/test/ui/consts/miri_unleashed/read_from_static.rs
new file mode 100644
index 0000000..821c501
--- /dev/null
+++ b/src/test/ui/consts/miri_unleashed/read_from_static.rs
@@ -0,0 +1,11 @@
+// run-pass
+// compile-flags: -Zunleash-the-miri-inside-of-you
+#![feature(const_mut_refs)]
+#![allow(const_err)]
+
+static OH_YES: &mut i32 = &mut 42;
+
+fn main() {
+    // Make sure `OH_YES` can be read.
+    assert_eq!(*OH_YES, 42);
+}
diff --git a/src/test/ui/consts/projection_qualif.mut_refs.stderr b/src/test/ui/consts/projection_qualif.mut_refs.stderr
new file mode 100644
index 0000000..2353877
--- /dev/null
+++ b/src/test/ui/consts/projection_qualif.mut_refs.stderr
@@ -0,0 +1,12 @@
+error[E0658]: dereferencing raw pointers in constants is unstable
+  --> $DIR/projection_qualif.rs:11:18
+   |
+LL |         unsafe { *b = 5; }
+   |                  ^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/51911
+   = help: add `#![feature(const_raw_ptr_deref)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/projection_qualif.rs b/src/test/ui/consts/projection_qualif.rs
index dedb7db..cfe8e7f 100644
--- a/src/test/ui/consts/projection_qualif.rs
+++ b/src/test/ui/consts/projection_qualif.rs
@@ -1,11 +1,15 @@
+// revisions: stock mut_refs
+
+#![cfg_attr(mut_refs, feature(const_mut_refs))]
+
 use std::cell::Cell;
 
 const FOO: &u32 = {
     let mut a = 42;
     {
-        let b: *mut u32 = &mut a; //~ ERROR may only refer to immutable values
+        let b: *mut u32 = &mut a; //[stock]~ ERROR may only refer to immutable values
         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
-        //~^ contains unimplemented expression
+        //[stock]~^ contains unimplemented expression
     }
     &{a}
 };
diff --git a/src/test/ui/consts/projection_qualif.stderr b/src/test/ui/consts/projection_qualif.stderr
deleted file mode 100644
index 0efb6bf..0000000
--- a/src/test/ui/consts/projection_qualif.stderr
+++ /dev/null
@@ -1,25 +0,0 @@
-error[E0017]: references in constants may only refer to immutable values
-  --> $DIR/projection_qualif.rs:6:27
-   |
-LL |         let b: *mut u32 = &mut a;
-   |                           ^^^^^^ constants require immutable values
-
-error[E0658]: dereferencing raw pointers in constants is unstable
-  --> $DIR/projection_qualif.rs:7:18
-   |
-LL |         unsafe { *b = 5; }
-   |                  ^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/51911
-   = help: add `#![feature(const_raw_ptr_deref)]` to the crate attributes to enable
-
-error[E0019]: constant contains unimplemented expression type
-  --> $DIR/projection_qualif.rs:7:18
-   |
-LL |         unsafe { *b = 5; }
-   |                  ^^^^^^
-
-error: aborting due to 3 previous errors
-
-Some errors have detailed explanations: E0017, E0019, E0658.
-For more information about an error, try `rustc --explain E0017`.
diff --git a/src/test/ui/consts/projection_qualif.stock.stderr b/src/test/ui/consts/projection_qualif.stock.stderr
new file mode 100644
index 0000000..472d260
--- /dev/null
+++ b/src/test/ui/consts/projection_qualif.stock.stderr
@@ -0,0 +1,28 @@
+error[E0658]: references in constants may only refer to immutable values
+  --> $DIR/projection_qualif.rs:10:27
+   |
+LL |         let b: *mut u32 = &mut a;
+   |                           ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0658]: dereferencing raw pointers in constants is unstable
+  --> $DIR/projection_qualif.rs:11:18
+   |
+LL |         unsafe { *b = 5; }
+   |                  ^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/51911
+   = help: add `#![feature(const_raw_ptr_deref)]` to the crate attributes to enable
+
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/projection_qualif.rs:11:18
+   |
+LL |         unsafe { *b = 5; }
+   |                  ^^^^^^
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0019, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.mut_refs.stderr b/src/test/ui/consts/static_mut_containing_mut_ref2.mut_refs.stderr
new file mode 100644
index 0000000..b43fbc8
--- /dev/null
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.mut_refs.stderr
@@ -0,0 +1,9 @@
+error[E0080]: could not evaluate static initializer
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:45
+   |
+LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
+   |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ tried to modify a static's initial value from another static's initializer
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.rs b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
index ef378fa..74162fb 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.rs
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
@@ -1,7 +1,12 @@
+// revisions: stock mut_refs
+
+#![cfg_attr(mut_refs, feature(const_mut_refs))]
+
 static mut STDERR_BUFFER_SPACE: u8 = 0;
 
 pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
-//~^ ERROR references in statics may only refer to immutable values
-//~| ERROR static contains unimplemented expression type
+//[mut_refs]~^ ERROR could not evaluate static initializer
+//[stock]~^^ ERROR references in statics may only refer to immutable values
+//[stock]~| ERROR static contains unimplemented expression type
 
 fn main() {}
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr b/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
deleted file mode 100644
index ca691b0..0000000
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
+++ /dev/null
@@ -1,16 +0,0 @@
-error[E0017]: references in statics may only refer to immutable values
-  --> $DIR/static_mut_containing_mut_ref2.rs:3:46
-   |
-LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
-   |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^ statics require immutable values
-
-error[E0019]: static contains unimplemented expression type
-  --> $DIR/static_mut_containing_mut_ref2.rs:3:45
-   |
-LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
-   |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 2 previous errors
-
-Some errors have detailed explanations: E0017, E0019.
-For more information about an error, try `rustc --explain E0017`.
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.stock.stderr b/src/test/ui/consts/static_mut_containing_mut_ref2.stock.stderr
new file mode 100644
index 0000000..430cef9
--- /dev/null
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.stock.stderr
@@ -0,0 +1,19 @@
+error[E0658]: references in statics may only refer to immutable values
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:46
+   |
+LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
+   |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:45
+   |
+LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
+   |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0019, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/enum/union-in-enum.rs b/src/test/ui/enum/union-in-enum.rs
new file mode 100644
index 0000000..048913e
--- /dev/null
+++ b/src/test/ui/enum/union-in-enum.rs
@@ -0,0 +1,13 @@
+// This test checks that the union keyword
+// is accepted as the name of an enum variant
+// when not followed by an identifier
+// This special case exists because `union` is a contextual keyword.
+
+#![allow(warnings)]
+
+// check-pass
+
+enum A { union }
+enum B { union {} }
+enum C { union() }
+fn main(){}
diff --git a/src/test/ui/error-codes/E0017.rs b/src/test/ui/error-codes/E0017.rs
index 3bc518c..64be411 100644
--- a/src/test/ui/error-codes/E0017.rs
+++ b/src/test/ui/error-codes/E0017.rs
@@ -2,10 +2,10 @@
 const C: i32 = 2;
 static mut M: i32 = 3;
 
-const CR: &'static mut i32 = &mut C; //~ ERROR E0017
-static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0017
+const CR: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0658
                                               //~| ERROR E0019
                                               //~| ERROR cannot borrow
-static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0017
-static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M }; //~ ERROR E0017
+static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M }; //~ ERROR E0658
 fn main() {}
diff --git a/src/test/ui/error-codes/E0017.stderr b/src/test/ui/error-codes/E0017.stderr
index 8c8660a..9a87195 100644
--- a/src/test/ui/error-codes/E0017.stderr
+++ b/src/test/ui/error-codes/E0017.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/E0017.rs:5:30
    |
 LL | const CR: &'static mut i32 = &mut C;
    |                              ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0019]: static contains unimplemented expression type
   --> $DIR/E0017.rs:6:39
@@ -10,11 +13,14 @@
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:6:39
    |
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0596]: cannot borrow immutable static item `X` as mutable
   --> $DIR/E0017.rs:6:39
@@ -22,19 +28,25 @@
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^ cannot borrow as mutable
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:9:38
    |
 LL | static CONST_REF: &'static mut i32 = &mut C;
    |                                      ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:10:52
    |
 LL | static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M };
    |                                                    ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0017, E0019, E0596.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0019, E0596, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/error-codes/E0388.rs b/src/test/ui/error-codes/E0388.rs
new file mode 100644
index 0000000..5954e34
--- /dev/null
+++ b/src/test/ui/error-codes/E0388.rs
@@ -0,0 +1,10 @@
+static X: i32 = 1;
+const C: i32 = 2;
+
+const CR: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0658
+                                              //~| ERROR cannot borrow
+                                              //~| ERROR E0019
+static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0658
+
+fn main() {}
diff --git a/src/test/ui/error-codes/E0388.stderr b/src/test/ui/error-codes/E0388.stderr
new file mode 100644
index 0000000..986307d
--- /dev/null
+++ b/src/test/ui/error-codes/E0388.stderr
@@ -0,0 +1,43 @@
+error[E0658]: references in constants may only refer to immutable values
+  --> $DIR/E0388.rs:4:30
+   |
+LL | const CR: &'static mut i32 = &mut C;
+   |                              ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^
+
+error[E0658]: references in statics may only refer to immutable values
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0596]: cannot borrow immutable static item `X` as mutable
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^ cannot borrow as mutable
+
+error[E0658]: references in statics may only refer to immutable values
+  --> $DIR/E0388.rs:8:38
+   |
+LL | static CONST_REF: &'static mut i32 = &mut C;
+   |                                      ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0019, E0596, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/for-loop-while/label_break_value.rs b/src/test/ui/for-loop-while/label_break_value.rs
index eb5be77..18930ac 100644
--- a/src/test/ui/for-loop-while/label_break_value.rs
+++ b/src/test/ui/for-loop-while/label_break_value.rs
@@ -77,7 +77,7 @@
         }
         // Labeled breaking an outer loop still works
         'd: loop {
-            'e: {
+            {
                 if v == r {
                     break 'b;
                 }
diff --git a/src/test/ui/for-loop-while/loop-label-shadowing.rs b/src/test/ui/for-loop-while/loop-label-shadowing.rs
index acb53e2..9bedde6 100644
--- a/src/test/ui/for-loop-while/loop-label-shadowing.rs
+++ b/src/test/ui/for-loop-while/loop-label-shadowing.rs
@@ -5,6 +5,7 @@
 
 fn main() {
     let mut foo = Vec::new();
+    #[allow(unused_labels)]
     'foo: for i in &[1, 2, 3] {
         foo.push(*i);
     }
diff --git a/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr b/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr
index b388f38..ca61fb0 100644
--- a/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr
+++ b/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr
@@ -4,7 +4,10 @@
 LL | fn bar(x: usize) -> Option<usize> {
    |                     ------------- expected `std::option::Option<usize>` because of return type
 LL |     return x;
-   |            ^ expected enum `std::option::Option`, found `usize`
+   |            ^
+   |            |
+   |            expected enum `std::option::Option`, found `usize`
+   |            help: try using a variant of the expected enum: `Some(x)`
    |
    = note: expected enum `std::option::Option<usize>`
               found type `usize`
diff --git a/src/test/ui/hrtb/hrtb-perfect-forwarding.polonius.stderr b/src/test/ui/hrtb/hrtb-perfect-forwarding.polonius.stderr
new file mode 100644
index 0000000..558d643
--- /dev/null
+++ b/src/test/ui/hrtb/hrtb-perfect-forwarding.polonius.stderr
@@ -0,0 +1,68 @@
+warning: function cannot return without recursing
+  --> $DIR/hrtb-perfect-forwarding.rs:22:1
+   |
+LL | / fn no_hrtb<'b,T>(mut t: T)
+LL | |     where T : Bar<&'b isize>
+LL | | {
+LL | |     // OK -- `T : Bar<&'b isize>`, and thus the impl above ensures that
+LL | |     // `&mut T : Bar<&'b isize>`.
+LL | |     no_hrtb(&mut t);
+   | |     --------------- recursive call site
+LL | | }
+   | |_^ cannot return without recursing
+   |
+   = note: `#[warn(unconditional_recursion)]` on by default
+   = help: a `loop` may express intention better if this is on purpose
+
+warning: function cannot return without recursing
+  --> $DIR/hrtb-perfect-forwarding.rs:30:1
+   |
+LL | / fn bar_hrtb<T>(mut t: T)
+LL | |     where T : for<'b> Bar<&'b isize>
+LL | | {
+LL | |     // OK -- `T : for<'b> Bar<&'b isize>`, and thus the impl above
+...  |
+LL | |     bar_hrtb(&mut t);
+   | |     ---------------- recursive call site
+LL | | }
+   | |_^ cannot return without recursing
+   |
+   = help: a `loop` may express intention better if this is on purpose
+
+warning: function cannot return without recursing
+  --> $DIR/hrtb-perfect-forwarding.rs:39:1
+   |
+LL | / fn foo_hrtb_bar_not<'b,T>(mut t: T)
+LL | |     where T : for<'a> Foo<&'a isize> + Bar<&'b isize>
+LL | | {
+LL | |     // Not OK -- The forwarding impl for `Foo` requires that `Bar` also
+...  |
+LL | |     foo_hrtb_bar_not(&mut t);
+   | |     ------------------------ recursive call site
+LL | | }
+   | |_^ cannot return without recursing
+   |
+   = help: a `loop` may express intention better if this is on purpose
+
+error: higher-ranked subtype error
+  --> $DIR/hrtb-perfect-forwarding.rs:46:5
+   |
+LL |     foo_hrtb_bar_not(&mut t);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: function cannot return without recursing
+  --> $DIR/hrtb-perfect-forwarding.rs:49:1
+   |
+LL | / fn foo_hrtb_bar_hrtb<T>(mut t: T)
+LL | |     where T : for<'a> Foo<&'a isize> + for<'b> Bar<&'b isize>
+LL | | {
+LL | |     // OK -- now we have `T : for<'b> Bar&'b isize>`.
+LL | |     foo_hrtb_bar_hrtb(&mut t);
+   | |     ------------------------- recursive call site
+LL | | }
+   | |_^ cannot return without recursing
+   |
+   = help: a `loop` may express intention better if this is on purpose
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/hygiene/hygienic-labels-in-let.rs b/src/test/ui/hygiene/hygienic-labels-in-let.rs
index 5d22cf8..491855d 100644
--- a/src/test/ui/hygiene/hygienic-labels-in-let.rs
+++ b/src/test/ui/hygiene/hygienic-labels-in-let.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(unreachable_code)]
+#![allow(unused_labels)]
 
 // Test that labels injected by macros do not break hygiene.  This
 // checks cases where the macros invocations are under the rhs of a
diff --git a/src/test/ui/hygiene/hygienic-labels-in-let.stderr b/src/test/ui/hygiene/hygienic-labels-in-let.stderr
index d88470f..4acb34f 100644
--- a/src/test/ui/hygiene/hygienic-labels-in-let.stderr
+++ b/src/test/ui/hygiene/hygienic-labels-in-let.stderr
@@ -1,5 +1,5 @@
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:15:9
+  --> $DIR/hygienic-labels-in-let.rs:16:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -11,7 +11,7 @@
    |             ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:63:9
+  --> $DIR/hygienic-labels-in-let.rs:64:9
    |
 LL |         'x: loop {
    |         -- first declared here
@@ -20,7 +20,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:63:9
+  --> $DIR/hygienic-labels-in-let.rs:64:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -29,7 +29,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:15:9
+  --> $DIR/hygienic-labels-in-let.rs:16:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -41,7 +41,7 @@
    |             ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:15:9
+  --> $DIR/hygienic-labels-in-let.rs:16:9
    |
 LL |         'x: loop { $e }
    |         ^^
@@ -53,7 +53,7 @@
    |             ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:15:9
+  --> $DIR/hygienic-labels-in-let.rs:16:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -65,7 +65,7 @@
    |             ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:75:9
+  --> $DIR/hygienic-labels-in-let.rs:76:9
    |
 LL |         'x: loop {
    |         -- first declared here
@@ -74,7 +74,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:75:9
+  --> $DIR/hygienic-labels-in-let.rs:76:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -83,7 +83,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:75:9
+  --> $DIR/hygienic-labels-in-let.rs:76:9
    |
 LL |         'x: for _ in 0..1 {
    |         -- first declared here
@@ -92,7 +92,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:75:9
+  --> $DIR/hygienic-labels-in-let.rs:76:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -101,7 +101,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:26:9
+  --> $DIR/hygienic-labels-in-let.rs:27:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -113,7 +113,7 @@
    |             ---------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:26:9
+  --> $DIR/hygienic-labels-in-let.rs:27:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -125,7 +125,7 @@
    |             ---------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:26:9
+  --> $DIR/hygienic-labels-in-let.rs:27:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -137,7 +137,7 @@
    |             ---------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:26:9
+  --> $DIR/hygienic-labels-in-let.rs:27:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -149,7 +149,7 @@
    |             ---------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:26:9
+  --> $DIR/hygienic-labels-in-let.rs:27:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -161,7 +161,7 @@
    |             ---------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: loop {
    |         -- first declared here
@@ -170,7 +170,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -179,7 +179,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: for _ in 0..1 {
    |         -- first declared here
@@ -188,7 +188,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -197,7 +197,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: for _ in 0..1 {
    |         -- first declared here
@@ -206,7 +206,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:89:9
+  --> $DIR/hygienic-labels-in-let.rs:90:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         -- first declared here
@@ -215,7 +215,7 @@
    |         ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -227,7 +227,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -239,7 +239,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -251,7 +251,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -263,7 +263,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -275,7 +275,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         -- first declared here
@@ -287,7 +287,7 @@
    |             ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels-in-let.rs:38:9
+  --> $DIR/hygienic-labels-in-let.rs:39:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
diff --git a/src/test/ui/hygiene/hygienic-labels.rs b/src/test/ui/hygiene/hygienic-labels.rs
index 8eafb4c..c9f494b 100644
--- a/src/test/ui/hygiene/hygienic-labels.rs
+++ b/src/test/ui/hygiene/hygienic-labels.rs
@@ -1,5 +1,6 @@
 // run-pass
 #![allow(unreachable_code)]
+#![allow(unused_labels)]
 // Test that labels injected by macros do not break hygiene.
 
 // Issue #24278: The label/lifetime shadowing checker from #24162
diff --git a/src/test/ui/hygiene/hygienic-labels.stderr b/src/test/ui/hygiene/hygienic-labels.stderr
index 285e903..0833825 100644
--- a/src/test/ui/hygiene/hygienic-labels.stderr
+++ b/src/test/ui/hygiene/hygienic-labels.stderr
@@ -1,5 +1,5 @@
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:12:9
+  --> $DIR/hygienic-labels.rs:13:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -11,7 +11,7 @@
    |         ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:53:5
+  --> $DIR/hygienic-labels.rs:54:5
    |
 LL |     'x: for _ in 0..1 {
    |     -- first declared here
@@ -20,7 +20,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:53:5
+  --> $DIR/hygienic-labels.rs:54:5
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -29,7 +29,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:12:9
+  --> $DIR/hygienic-labels.rs:13:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -41,7 +41,7 @@
    |         ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:12:9
+  --> $DIR/hygienic-labels.rs:13:9
    |
 LL |         'x: loop { $e }
    |         ^^
@@ -53,7 +53,7 @@
    |         ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:12:9
+  --> $DIR/hygienic-labels.rs:13:9
    |
 LL |         'x: loop { $e }
    |         ^^ lifetime 'x already in scope
@@ -65,7 +65,7 @@
    |         ------------------ in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:62:5
+  --> $DIR/hygienic-labels.rs:63:5
    |
 LL |     'x: for _ in 0..1 {
    |     -- first declared here
@@ -74,7 +74,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:62:5
+  --> $DIR/hygienic-labels.rs:63:5
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -83,7 +83,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:62:5
+  --> $DIR/hygienic-labels.rs:63:5
    |
 LL |     'x: loop {
    |     -- first declared here
@@ -92,7 +92,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:62:5
+  --> $DIR/hygienic-labels.rs:63:5
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -101,7 +101,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:37:9
+  --> $DIR/hygienic-labels.rs:38:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -113,7 +113,7 @@
    |         ------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:37:9
+  --> $DIR/hygienic-labels.rs:38:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -125,7 +125,7 @@
    |         ------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:37:9
+  --> $DIR/hygienic-labels.rs:38:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -137,7 +137,7 @@
    |         ------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:37:9
+  --> $DIR/hygienic-labels.rs:38:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -149,7 +149,7 @@
    |         ------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:37:9
+  --> $DIR/hygienic-labels.rs:38:9
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         ^^ lifetime 'x already in scope
@@ -161,7 +161,7 @@
    |         ------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |     'x: for _ in 0..1 {
    |     -- first declared here
@@ -170,7 +170,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -179,7 +179,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |     'x: loop {
    |     -- first declared here
@@ -188,7 +188,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -197,7 +197,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |     'x: while 1 + 1 == 2 {
    |     -- first declared here
@@ -206,7 +206,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:72:5
+  --> $DIR/hygienic-labels.rs:73:5
    |
 LL |         'x: while 1 + 1 == 2 { $e }
    |         -- first declared here
@@ -215,7 +215,7 @@
    |     ^^ lifetime 'x already in scope
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -227,7 +227,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -239,7 +239,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -251,7 +251,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: loop { $e }
    |         -- first declared here
@@ -263,7 +263,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -275,7 +275,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
@@ -287,7 +287,7 @@
    |         ----------------------- in this macro invocation
 
 warning: label name `'x` shadows a label name that is already in scope
-  --> $DIR/hygienic-labels.rs:23:9
+  --> $DIR/hygienic-labels.rs:24:9
    |
 LL |         'x: for _ in 0..1 { $e }
    |         ^^ lifetime 'x already in scope
diff --git a/src/test/ui/impl-trait/multiple-lifetimes/error-handling.polonius.stderr b/src/test/ui/impl-trait/multiple-lifetimes/error-handling.polonius.stderr
new file mode 100644
index 0000000..72e8fa3
--- /dev/null
+++ b/src/test/ui/impl-trait/multiple-lifetimes/error-handling.polonius.stderr
@@ -0,0 +1,12 @@
+error: lifetime may not live long enough
+  --> $DIR/error-handling.rs:13:56
+   |
+LL | fn foo<'a, 'b, 'c>(x: &'static i32, mut y: &'a i32) -> E<'b, 'c> {
+   |        --  -- lifetime `'b` defined here               ^^^^^^^^^ opaque type requires that `'a` must outlive `'b`
+   |        |
+   |        lifetime `'a` defined here
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/issues/issue-17718-const-bad-values.stderr b/src/test/ui/issues/issue-17718-const-bad-values.stderr
index 8d875d3..7e4a62a 100644
--- a/src/test/ui/issues/issue-17718-const-bad-values.stderr
+++ b/src/test/ui/issues/issue-17718-const-bad-values.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/issue-17718-const-bad-values.rs:1:34
    |
 LL | const C1: &'static mut [usize] = &mut [];
    |                                  ^^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0013]: constants cannot refer to statics, use a constant instead
   --> $DIR/issue-17718-const-bad-values.rs:5:46
@@ -10,13 +13,16 @@
 LL | const C2: &'static mut usize = unsafe { &mut S };
    |                                              ^
 
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/issue-17718-const-bad-values.rs:5:41
    |
 LL | const C2: &'static mut usize = unsafe { &mut S };
    |                                         ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0013, E0017.
+Some errors have detailed explanations: E0013, E0658.
 For more information about an error, try `rustc --explain E0013`.
diff --git a/src/test/ui/issues/issue-2216.rs b/src/test/ui/issues/issue-2216.rs
index fa712ed..ad54107 100644
--- a/src/test/ui/issues/issue-2216.rs
+++ b/src/test/ui/issues/issue-2216.rs
@@ -5,7 +5,7 @@
 
     'foo: loop {
         'bar: loop {
-            'quux: loop {
+            loop {
                 if 1 == 2 {
                     break 'foo;
                 }
diff --git a/src/test/ui/issues/issue-46604.rs b/src/test/ui/issues/issue-46604.rs
index 4f1ad38..e1967eb 100644
--- a/src/test/ui/issues/issue-46604.rs
+++ b/src/test/ui/issues/issue-46604.rs
@@ -1,4 +1,4 @@
-static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];   //~ ERROR E0017
+static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];   //~ ERROR E0658
 fn write<T: AsRef<[u8]>>(buffer: T) { }
 
 fn main() {
diff --git a/src/test/ui/issues/issue-46604.stderr b/src/test/ui/issues/issue-46604.stderr
index c72f580..32c7ecb 100644
--- a/src/test/ui/issues/issue-46604.stderr
+++ b/src/test/ui/issues/issue-46604.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/issue-46604.rs:1:25
    |
 LL | static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];
    |                         ^^^^^^^^^^^^^^^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0594]: cannot assign to `buf[_]`, as `buf` is an immutable static item
   --> $DIR/issue-46604.rs:6:5
@@ -12,5 +15,5 @@
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0017, E0594.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0594, E0658.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/issues/issue-51632-try-desugar-incompatible-types.stderr b/src/test/ui/issues/issue-51632-try-desugar-incompatible-types.stderr
index aef6dc5..9ca983d 100644
--- a/src/test/ui/issues/issue-51632-try-desugar-incompatible-types.stderr
+++ b/src/test/ui/issues/issue-51632-try-desugar-incompatible-types.stderr
@@ -2,13 +2,18 @@
   --> $DIR/issue-51632-try-desugar-incompatible-types.rs:8:5
    |
 LL |     missing_discourses()?
-   |     ^^^^^^^^^^^^^^^^^^^^-
-   |     |                   |
-   |     |                   help: try removing this `?`
-   |     expected enum `std::result::Result`, found `isize`
+   |     ^^^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found `isize`
    |
    = note: expected enum `std::result::Result<isize, ()>`
               found type `isize`
+help: try removing this `?`
+   |
+LL |     missing_discourses()
+   |                        --
+help: try using a variant of the expected enum
+   |
+LL |     Ok(missing_discourses()?)
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-54348.rs b/src/test/ui/issues/issue-54348.rs
index e7221e2..68d8380 100644
--- a/src/test/ui/issues/issue-54348.rs
+++ b/src/test/ui/issues/issue-54348.rs
@@ -1,7 +1,5 @@
 fn main() {
     [1][0u64 as usize];
     [1][1.5 as usize]; //~ ERROR index out of bounds
-    //~| ERROR this expression will panic at runtime
     [1][1u64 as usize]; //~ ERROR index out of bounds
-    //~| ERROR this expression will panic at runtime
 }
diff --git a/src/test/ui/issues/issue-54348.stderr b/src/test/ui/issues/issue-54348.stderr
index 79320ef..fa77bd6 100644
--- a/src/test/ui/issues/issue-54348.stderr
+++ b/src/test/ui/issues/issue-54348.stderr
@@ -6,23 +6,11 @@
    |
    = note: `#[deny(const_err)]` on by default
 
-error: this expression will panic at runtime
-  --> $DIR/issue-54348.rs:3:5
-   |
-LL |     [1][1.5 as usize];
-   |     ^^^^^^^^^^^^^^^^^ index out of bounds: the len is 1 but the index is 1
-
 error: index out of bounds: the len is 1 but the index is 1
-  --> $DIR/issue-54348.rs:5:5
+  --> $DIR/issue-54348.rs:4:5
    |
 LL |     [1][1u64 as usize];
    |     ^^^^^^^^^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-54348.rs:5:5
-   |
-LL |     [1][1u64 as usize];
-   |     ^^^^^^^^^^^^^^^^^^ index out of bounds: the len is 1 but the index is 1
-
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-59756.rs b/src/test/ui/issues/issue-59756.rs
index cccae39..d6df059 100644
--- a/src/test/ui/issues/issue-59756.rs
+++ b/src/test/ui/issues/issue-59756.rs
@@ -1,4 +1,8 @@
 // run-rustfix
+// ignore-test
+//
+// FIXME: Re-enable this test once we support choosing
+// between multiple mutually exclusive suggestions for the same span
 
 #![allow(warnings)]
 
diff --git a/src/test/ui/issues/issue-59756.stderr b/src/test/ui/issues/issue-59756.stderr
index 150916c..9066e57 100644
--- a/src/test/ui/issues/issue-59756.stderr
+++ b/src/test/ui/issues/issue-59756.stderr
@@ -2,13 +2,18 @@
   --> $DIR/issue-59756.rs:13:5
    |
 LL |     foo()?
-   |     ^^^^^-
-   |     |    |
-   |     |    help: try removing this `?`
-   |     expected enum `std::result::Result`, found struct `A`
+   |     ^^^^^^ expected enum `std::result::Result`, found struct `A`
    |
    = note: expected enum `std::result::Result<A, B>`
             found struct `A`
+help: try removing this `?`
+   |
+LL |     foo()
+   |         --
+help: try using a variant of the expected enum
+   |
+LL |     Ok(foo()?)
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-8460-const.rs b/src/test/ui/issues/issue-8460-const.rs
index 4637814..71e2b58 100644
--- a/src/test/ui/issues/issue-8460-const.rs
+++ b/src/test/ui/issues/issue-8460-const.rs
@@ -23,19 +23,14 @@
     //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
     //~| ERROR this expression will panic at runtime
@@ -53,17 +48,12 @@
     //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
 }
diff --git a/src/test/ui/issues/issue-8460-const.stderr b/src/test/ui/issues/issue-8460-const.stderr
index 7e5a22e..c6750e6 100644
--- a/src/test/ui/issues/issue-8460-const.stderr
+++ b/src/test/ui/issues/issue-8460-const.stderr
@@ -70,179 +70,119 @@
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:24:36
-   |
-LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
-   |                                    ^^^^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:27:36
+  --> $DIR/issue-8460-const.rs:26:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:27:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
-   |                                    ^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:30:36
+  --> $DIR/issue-8460-const.rs:28:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
+error: attempt to divide by zero
   --> $DIR/issue-8460-const.rs:30:36
    |
-LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
-error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:33:36
-   |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:33:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:36:36
+  --> $DIR/issue-8460-const.rs:32:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:36:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:39:36
+  --> $DIR/issue-8460-const.rs:34:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:39:36
+  --> $DIR/issue-8460-const.rs:34:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:42:36
+  --> $DIR/issue-8460-const.rs:37:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:42:36
+  --> $DIR/issue-8460-const.rs:37:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:45:36
+  --> $DIR/issue-8460-const.rs:40:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:45:36
+  --> $DIR/issue-8460-const.rs:40:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:48:36
+  --> $DIR/issue-8460-const.rs:43:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:48:36
+  --> $DIR/issue-8460-const.rs:43:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:51:36
+  --> $DIR/issue-8460-const.rs:46:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:51:36
+  --> $DIR/issue-8460-const.rs:46:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:54:36
+  --> $DIR/issue-8460-const.rs:49:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:54:36
-   |
-LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
-   |                                    ^^^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:57:36
+  --> $DIR/issue-8460-const.rs:51:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^
 
-error: this expression will panic at runtime
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const.rs:53:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const.rs:55:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: attempt to calculate the remainder with a divisor of zero
   --> $DIR/issue-8460-const.rs:57:36
    |
-LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
-   |                                    ^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:60:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
-   |                                    ^^^^^^^^
-
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:60:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:63:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
-   |                                    ^^^^^^^^
-
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:63:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:66:36
-   |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:66:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: aborting due to 40 previous errors
+error: aborting due to 30 previous errors
 
diff --git a/src/test/ui/issues/issue-8460-const2.rs b/src/test/ui/issues/issue-8460-const2.rs
index c3f53e3..723a179 100644
--- a/src/test/ui/issues/issue-8460-const2.rs
+++ b/src/test/ui/issues/issue-8460-const2.rs
@@ -18,19 +18,14 @@
     //~^ ERROR attempt to divide with overflow
     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
@@ -43,17 +38,12 @@
     //~^ ERROR attempt to calculate the remainder with overflow
     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
-    //~| ERROR this expression will panic at runtime
 }
diff --git a/src/test/ui/issues/issue-8460-const2.stderr b/src/test/ui/issues/issue-8460-const2.stderr
index b688ec1..87b9b2d 100644
--- a/src/test/ui/issues/issue-8460-const2.stderr
+++ b/src/test/ui/issues/issue-8460-const2.stderr
@@ -40,149 +40,89 @@
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:19:36
-   |
-LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
-   |                                    ^^^^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const2.rs:22:36
+  --> $DIR/issue-8460-const2.rs:21:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:22:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
-   |                                    ^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const2.rs:25:36
+  --> $DIR/issue-8460-const2.rs:23:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
+error: attempt to divide by zero
   --> $DIR/issue-8460-const2.rs:25:36
    |
-LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
-error: attempt to divide by zero
-  --> $DIR/issue-8460-const2.rs:28:36
-   |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:28:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const2.rs:31:36
+  --> $DIR/issue-8460-const2.rs:27:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:31:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to divide by zero
-
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const2.rs:34:36
+  --> $DIR/issue-8460-const2.rs:29:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const2.rs:36:36
+  --> $DIR/issue-8460-const2.rs:31:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const2.rs:38:36
+  --> $DIR/issue-8460-const2.rs:33:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const2.rs:40:36
+  --> $DIR/issue-8460-const2.rs:35:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const2.rs:42:36
+  --> $DIR/issue-8460-const2.rs:37:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const2.rs:44:36
+  --> $DIR/issue-8460-const2.rs:39:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:44:36
-   |
-LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
-   |                                    ^^^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const2.rs:47:36
+  --> $DIR/issue-8460-const2.rs:41:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^
 
-error: this expression will panic at runtime
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:43:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: attempt to calculate the remainder with a divisor of zero
+  --> $DIR/issue-8460-const2.rs:45:36
+   |
+LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
+   |                                    ^^^^^^^^
+
+error: attempt to calculate the remainder with a divisor of zero
   --> $DIR/issue-8460-const2.rs:47:36
    |
-LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
-   |                                    ^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const2.rs:50:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
-   |                                    ^^^^^^^^
-
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:50:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const2.rs:53:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
-   |                                    ^^^^^^^^
-
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:53:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const2.rs:56:36
-   |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/issue-8460-const2.rs:56:36
-   |
-LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
-   |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
-
-error: aborting due to 30 previous errors
+error: aborting due to 20 previous errors
 
diff --git a/src/test/ui/macros/macro-lifetime-used-with-labels.rs b/src/test/ui/macros/macro-lifetime-used-with-labels.rs
index 86a3e9f..2e9da6f 100644
--- a/src/test/ui/macros/macro-lifetime-used-with-labels.rs
+++ b/src/test/ui/macros/macro-lifetime-used-with-labels.rs
@@ -1,6 +1,6 @@
 // run-pass
 #![allow(stable_features)]
-
+#![allow(unused_labels)]
 #![allow(unreachable_code)]
 
 macro_rules! x {
diff --git a/src/test/ui/malformed/malformed-derive-entry.rs b/src/test/ui/malformed/malformed-derive-entry.rs
index a6d8863..77fa2f5 100644
--- a/src/test/ui/malformed/malformed-derive-entry.rs
+++ b/src/test/ui/malformed/malformed-derive-entry.rs
@@ -1,7 +1,11 @@
-#[derive(Copy(Bad))] //~ ERROR expected one of `)`, `,`, or `::`, found `(`
+#[derive(Copy(Bad))]
+//~^ ERROR traits in `#[derive(...)]` don't accept arguments
+//~| ERROR the trait bound
 struct Test1;
 
-#[derive(Copy="bad")] //~ ERROR expected one of `)`, `,`, or `::`, found `=`
+#[derive(Copy="bad")]
+//~^ ERROR traits in `#[derive(...)]` don't accept values
+//~| ERROR the trait bound
 struct Test2;
 
 #[derive] //~ ERROR malformed `derive` attribute input
diff --git a/src/test/ui/malformed/malformed-derive-entry.stderr b/src/test/ui/malformed/malformed-derive-entry.stderr
index 8d750b6..1f1ee39 100644
--- a/src/test/ui/malformed/malformed-derive-entry.stderr
+++ b/src/test/ui/malformed/malformed-derive-entry.stderr
@@ -1,20 +1,33 @@
-error: expected one of `)`, `,`, or `::`, found `(`
+error: traits in `#[derive(...)]` don't accept arguments
   --> $DIR/malformed-derive-entry.rs:1:14
    |
 LL | #[derive(Copy(Bad))]
-   |              ^ expected one of `)`, `,`, or `::`
+   |              ^^^^^ help: remove the arguments
 
-error: expected one of `)`, `,`, or `::`, found `=`
-  --> $DIR/malformed-derive-entry.rs:4:14
+error: traits in `#[derive(...)]` don't accept values
+  --> $DIR/malformed-derive-entry.rs:6:14
    |
 LL | #[derive(Copy="bad")]
-   |              ^ expected one of `)`, `,`, or `::`
+   |              ^^^^^^ help: remove the value
 
 error: malformed `derive` attribute input
-  --> $DIR/malformed-derive-entry.rs:7:1
+  --> $DIR/malformed-derive-entry.rs:11:1
    |
 LL | #[derive]
    | ^^^^^^^^^ help: missing traits to be derived: `#[derive(Trait1, Trait2, ...)]`
 
-error: aborting due to 3 previous errors
+error[E0277]: the trait bound `Test1: std::clone::Clone` is not satisfied
+  --> $DIR/malformed-derive-entry.rs:1:10
+   |
+LL | #[derive(Copy(Bad))]
+   |          ^^^^ the trait `std::clone::Clone` is not implemented for `Test1`
 
+error[E0277]: the trait bound `Test2: std::clone::Clone` is not satisfied
+  --> $DIR/malformed-derive-entry.rs:6:10
+   |
+LL | #[derive(Copy="bad")]
+   |          ^^^^ the trait `std::clone::Clone` is not implemented for `Test2`
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/malformed/malformed-meta-delim.rs b/src/test/ui/malformed/malformed-meta-delim.rs
new file mode 100644
index 0000000..5b1614b
--- /dev/null
+++ b/src/test/ui/malformed/malformed-meta-delim.rs
@@ -0,0 +1,11 @@
+fn main() {}
+
+#[allow { foo_lint } ]
+//~^ ERROR wrong meta list delimiters
+//~| HELP the delimiters should be `(` and `)`
+fn delim_brace() {}
+
+#[allow [ foo_lint ] ]
+//~^ ERROR wrong meta list delimiters
+//~| HELP the delimiters should be `(` and `)`
+fn delim_bracket() {}
diff --git a/src/test/ui/malformed/malformed-meta-delim.stderr b/src/test/ui/malformed/malformed-meta-delim.stderr
new file mode 100644
index 0000000..407193d
--- /dev/null
+++ b/src/test/ui/malformed/malformed-meta-delim.stderr
@@ -0,0 +1,24 @@
+error: wrong meta list delimiters
+  --> $DIR/malformed-meta-delim.rs:3:9
+   |
+LL | #[allow { foo_lint } ]
+   |         ^^^^^^^^^^^^
+   |
+help: the delimiters should be `(` and `)`
+   |
+LL | #[allow ( foo_lint ) ]
+   |         ^          ^
+
+error: wrong meta list delimiters
+  --> $DIR/malformed-meta-delim.rs:8:9
+   |
+LL | #[allow [ foo_lint ] ]
+   |         ^^^^^^^^^^^^
+   |
+help: the delimiters should be `(` and `)`
+   |
+LL | #[allow ( foo_lint ) ]
+   |         ^          ^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/malformed/malformed-special-attrs.rs b/src/test/ui/malformed/malformed-special-attrs.rs
index e67fbdd..05b7ebe 100644
--- a/src/test/ui/malformed/malformed-special-attrs.rs
+++ b/src/test/ui/malformed/malformed-special-attrs.rs
@@ -1,7 +1,7 @@
 #[cfg_attr] //~ ERROR malformed `cfg_attr` attribute
 struct S1;
 
-#[cfg_attr = ""] //~ ERROR expected `(`, found `=`
+#[cfg_attr = ""] //~ ERROR malformed `cfg_attr` attribute
 struct S2;
 
 #[derive] //~ ERROR malformed `derive` attribute
diff --git a/src/test/ui/malformed/malformed-special-attrs.stderr b/src/test/ui/malformed/malformed-special-attrs.stderr
index 319c05e..6f535e0 100644
--- a/src/test/ui/malformed/malformed-special-attrs.stderr
+++ b/src/test/ui/malformed/malformed-special-attrs.stderr
@@ -6,11 +6,13 @@
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
-error: expected `(`, found `=`
-  --> $DIR/malformed-special-attrs.rs:4:12
+error: malformed `cfg_attr` attribute input
+  --> $DIR/malformed-special-attrs.rs:4:1
    |
 LL | #[cfg_attr = ""]
-   |            ^ expected `(`
+   | ^^^^^^^^^^^^^^^^ help: missing condition and attribute: `#[cfg_attr(condition, attribute, other_attribute, ...)]`
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error: malformed `derive` attribute input
   --> $DIR/malformed-special-attrs.rs:7:1
diff --git a/src/test/ui/mismatched_types/abridged.stderr b/src/test/ui/mismatched_types/abridged.stderr
index c208187..c731306 100644
--- a/src/test/ui/mismatched_types/abridged.stderr
+++ b/src/test/ui/mismatched_types/abridged.stderr
@@ -26,7 +26,10 @@
 LL | fn b() -> Option<Foo> {
    |           ----------- expected `std::option::Option<Foo>` because of return type
 LL |     Foo { bar: 1 }
-   |     ^^^^^^^^^^^^^^ expected enum `std::option::Option`, found struct `Foo`
+   |     ^^^^^^^^^^^^^^
+   |     |
+   |     expected enum `std::option::Option`, found struct `Foo`
+   |     help: try using a variant of the expected enum: `Some(Foo { bar: 1 })`
    |
    = note: expected enum `std::option::Option<Foo>`
             found struct `Foo`
@@ -37,7 +40,10 @@
 LL | fn c() -> Result<Foo, Bar> {
    |           ---------------- expected `std::result::Result<Foo, Bar>` because of return type
 LL |     Foo { bar: 1 }
-   |     ^^^^^^^^^^^^^^ expected enum `std::result::Result`, found struct `Foo`
+   |     ^^^^^^^^^^^^^^
+   |     |
+   |     expected enum `std::result::Result`, found struct `Foo`
+   |     help: try using a variant of the expected enum: `Ok(Foo { bar: 1 })`
    |
    = note: expected enum `std::result::Result<Foo, Bar>`
             found struct `Foo`
diff --git a/src/test/ui/nll/outlives-suggestion-simple.polonius.stderr b/src/test/ui/nll/outlives-suggestion-simple.polonius.stderr
new file mode 100644
index 0000000..8157446
--- /dev/null
+++ b/src/test/ui/nll/outlives-suggestion-simple.polonius.stderr
@@ -0,0 +1,121 @@
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:6:5
+   |
+LL | fn foo1<'a, 'b>(x: &'a usize) -> &'b usize {
+   |         --  -- lifetime `'b` defined here
+   |         |
+   |         lifetime `'a` defined here
+LL |     x
+   |     ^ returning this value requires that `'a` must outlive `'b`
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:10:5
+   |
+LL | fn foo2<'a>(x: &'a usize) -> &'static usize {
+   |         -- lifetime `'a` defined here
+LL |     x
+   |     ^ returning this value requires that `'a` must outlive `'static`
+   |
+   = help: consider replacing `'a` with `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:14:5
+   |
+LL | fn foo3<'a, 'b>(x: &'a usize, y: &'b usize) -> (&'b usize, &'a usize) {
+   |         --  -- lifetime `'b` defined here
+   |         |
+   |         lifetime `'a` defined here
+LL |     (x, y)
+   |     ^^^^^^ function was supposed to return data with lifetime `'b` but it is returning data with lifetime `'a`
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:14:5
+   |
+LL | fn foo3<'a, 'b>(x: &'a usize, y: &'b usize) -> (&'b usize, &'a usize) {
+   |         --  -- lifetime `'b` defined here
+   |         |
+   |         lifetime `'a` defined here
+LL |     (x, y)
+   |     ^^^^^^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'b`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+help: `'a` and `'b` must be the same: replace one with the other
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:22:5
+   |
+LL | fn foo4<'a, 'b, 'c>(x: &'a usize) -> (&'b usize, &'c usize) {
+   |         --  -- lifetime `'b` defined here
+   |         |
+   |         lifetime `'a` defined here
+...
+LL |     (x, x)
+   |     ^^^^^^ returning this value requires that `'a` must outlive `'b`
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:22:5
+   |
+LL | fn foo4<'a, 'b, 'c>(x: &'a usize) -> (&'b usize, &'c usize) {
+   |         --      -- lifetime `'c` defined here
+   |         |
+   |         lifetime `'a` defined here
+...
+LL |     (x, x)
+   |     ^^^^^^ returning this value requires that `'a` must outlive `'c`
+   |
+   = help: consider adding the following bound: `'a: 'c`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:31:9
+   |
+LL |     pub fn foo<'a>(x: &'a usize) -> Self {
+   |                -- lifetime `'a` defined here
+LL |         Foo { x }
+   |         ^^^^^^^^^ returning this value requires that `'a` must outlive `'static`
+   |
+   = help: consider replacing `'a` with `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:41:9
+   |
+LL | impl<'a> Bar<'a> {
+   |      -- lifetime `'a` defined here
+LL |     pub fn get<'b>(&self) -> &'b usize {
+   |                -- lifetime `'b` defined here
+LL |         self.x
+   |         ^^^^^^ returning this value requires that `'a` must outlive `'b`
+   |
+   = help: consider adding the following bound: `'a: 'b`
+
+error: lifetime may not live long enough
+  --> $DIR/outlives-suggestion-simple.rs:52:9
+   |
+LL | impl<'a> Baz<'a> {
+   |      -- lifetime `'a` defined here
+LL |     fn get<'b>(&'b self) -> &'a i32 {
+   |            -- lifetime `'b` defined here
+LL |         self.x
+   |         ^^^^^^ returning this value requires that `'b` must outlive `'a`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+error[E0521]: borrowed data escapes outside of function
+  --> $DIR/outlives-suggestion-simple.rs:73:9
+   |
+LL |     fn get_bar(&self) -> Bar2 {
+   |                -----
+   |                |
+   |                `self` is declared here, outside of the function body
+   |                `self` is a reference that is only valid in the function body
+LL |         Bar2::new(&self)
+   |         ^^^^^^^^^^^^^^^^ `self` escapes the function body here
+
+error: aborting due to 10 previous errors
+
diff --git a/src/test/ui/nll/polonius/subset-relations.rs b/src/test/ui/nll/polonius/subset-relations.rs
new file mode 100644
index 0000000..3f6f67e
--- /dev/null
+++ b/src/test/ui/nll/polonius/subset-relations.rs
@@ -0,0 +1,30 @@
+// Checks that Polonius can compute cases of universal regions errors:
+// "illegal subset relation errors", cases where analysis finds that
+// two free regions outlive each other, without any evidence that this
+// relation holds.
+
+// ignore-compare-mode-nll
+// compile-flags: -Z borrowck=mir -Zpolonius
+
+// returning `y` requires that `'b: 'a`, but it's not known to be true
+fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
+    y //~ ERROR
+}
+
+// `'b: 'a` is explicitly declared
+fn valid_subset<'a, 'b: 'a>(x: &'a u32, y: &'b u32) -> &'a u32 {
+    y
+}
+
+// because of `x`, it is implied that `'b: 'a` holds
+fn implied_bounds_subset<'a, 'b>(x: &'a &'b mut u32) -> &'a u32 {
+    x
+}
+
+// `'b: 'a` is declared, and `'a: 'c` is known via implied bounds:
+// `'b: 'c` is therefore known to hold transitively
+fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32  {
+    y
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/polonius/subset-relations.stderr b/src/test/ui/nll/polonius/subset-relations.stderr
new file mode 100644
index 0000000..6364510
--- /dev/null
+++ b/src/test/ui/nll/polonius/subset-relations.stderr
@@ -0,0 +1,14 @@
+error: lifetime may not live long enough
+  --> $DIR/subset-relations.rs:11:5
+   |
+LL | fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
+   |                   --  -- lifetime `'b` defined here
+   |                   |
+   |                   lifetime `'a` defined here
+LL |     y
+   |     ^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'b`
+   |
+   = help: consider adding the following bound: `'b: 'a`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/nll/user-annotations/closure-substs.polonius.stderr b/src/test/ui/nll/user-annotations/closure-substs.polonius.stderr
new file mode 100644
index 0000000..d5bcdf6
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/closure-substs.polonius.stderr
@@ -0,0 +1,60 @@
+error: lifetime may not live long enough
+  --> $DIR/closure-substs.rs:8:16
+   |
+LL | fn foo<'a>() {
+   |        -- lifetime `'a` defined here
+...
+LL |         return x;
+   |                ^ returning this value requires that `'a` must outlive `'static`
+   |
+   = help: consider replacing `'a` with `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/closure-substs.rs:15:16
+   |
+LL |     |x: &i32| -> &'static i32 {
+   |         - let's call the lifetime of this reference `'1`
+LL |         return x;
+   |                ^ returning this value requires that `'1` must outlive `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/closure-substs.rs:15:16
+   |
+LL |     |x: &i32| -> &'static i32 {
+   |         -        ------------ return type of closure is &'2 i32
+   |         |
+   |         let's call the lifetime of this reference `'1`
+LL |         return x;
+   |                ^ returning this value requires that `'1` must outlive `'2`
+
+error: lifetime may not live long enough
+  --> $DIR/closure-substs.rs:22:9
+   |
+LL | fn bar<'a>() {
+   |        -- lifetime `'a` defined here
+...
+LL |         b(x);
+   |         ^^^^ argument requires that `'a` must outlive `'static`
+   |
+   = help: consider replacing `'a` with `'static`
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/closure-substs.rs:29:9
+   |
+LL |     |x: &i32, b: fn(&'static i32)| {
+   |      - `x` is a reference that is only valid in the closure body
+LL |         b(x);
+   |         ^^^^ `x` escapes the closure body here
+
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/closure-substs.rs:29:9
+   |
+LL |     |x: &i32, b: fn(&'static i32)| {
+   |      -        - `b` is declared here, outside of the closure body
+   |      |
+   |      `x` is a reference that is only valid in the closure body
+LL |         b(x);
+   |         ^^^^ `x` escapes the closure body here
+
+error: aborting due to 6 previous errors
+
diff --git a/src/test/ui/on-unimplemented/expected-comma-found-token.rs b/src/test/ui/on-unimplemented/expected-comma-found-token.rs
index 77c0ea1..8fb34f2 100644
--- a/src/test/ui/on-unimplemented/expected-comma-found-token.rs
+++ b/src/test/ui/on-unimplemented/expected-comma-found-token.rs
@@ -6,7 +6,7 @@
 
 #[rustc_on_unimplemented(
     message="the message"
-    label="the label" //~ ERROR expected one of `)` or `,`, found `label`
+    label="the label" //~ ERROR expected `,`, found `label`
 )]
 trait T {}
 
diff --git a/src/test/ui/on-unimplemented/expected-comma-found-token.stderr b/src/test/ui/on-unimplemented/expected-comma-found-token.stderr
index 2e1d484..048b72e 100644
--- a/src/test/ui/on-unimplemented/expected-comma-found-token.stderr
+++ b/src/test/ui/on-unimplemented/expected-comma-found-token.stderr
@@ -1,11 +1,8 @@
-error: expected one of `)` or `,`, found `label`
+error: expected `,`, found `label`
   --> $DIR/expected-comma-found-token.rs:9:5
    |
 LL |     message="the message"
-   |                          -
-   |                          |
-   |                          expected one of `)` or `,`
-   |                          help: missing `,`
+   |                          - expected `,`
 LL |     label="the label"
    |     ^^^^^ unexpected token
 
diff --git a/src/test/ui/proc-macro/span-preservation.stderr b/src/test/ui/proc-macro/span-preservation.stderr
index cd6f0ea..a77e920 100644
--- a/src/test/ui/proc-macro/span-preservation.stderr
+++ b/src/test/ui/proc-macro/span-preservation.stderr
@@ -14,6 +14,11 @@
 LL |     match x {
 LL |         Some(x) => { return x },
    |                             ^ expected `usize`, found `isize`
+   |
+help: you can convert an `isize` to `usize` and panic if the converted value wouldn't fit
+   |
+LL |         Some(x) => { return x.try_into().unwrap() },
+   |                             ^^^^^^^^^^^^^^^^^^^^^
 
 error[E0308]: mismatched types
   --> $DIR/span-preservation.rs:33:22
diff --git a/src/test/ui/rfc-2091-track-caller/caller-location-intrinsic.rs b/src/test/ui/rfc-2091-track-caller/caller-location-intrinsic.rs
index 1c4d466..0a79aea 100644
--- a/src/test/ui/rfc-2091-track-caller/caller-location-intrinsic.rs
+++ b/src/test/ui/rfc-2091-track-caller/caller-location-intrinsic.rs
@@ -1,21 +1,27 @@
 // run-pass
 
-#![feature(core_intrinsics)]
+#![feature(track_caller)]
+
+#[inline(never)]
+#[track_caller]
+fn defeat_const_prop() -> &'static core::panic::Location<'static> {
+    core::panic::Location::caller()
+}
 
 macro_rules! caller_location_from_macro {
-    () => (core::intrinsics::caller_location());
+    () => (defeat_const_prop());
 }
 
 fn main() {
-    let loc = core::intrinsics::caller_location();
+    let loc = defeat_const_prop();
     assert_eq!(loc.file(), file!());
-    assert_eq!(loc.line(), 10);
+    assert_eq!(loc.line(), 16);
     assert_eq!(loc.column(), 15);
 
-    // `caller_location()` in a macro should behave similarly to `file!` and `line!`,
+    // `Location::caller()` in a macro should behave similarly to `file!` and `line!`,
     // i.e. point to where the macro was invoked, instead of the macro itself.
     let loc2 = caller_location_from_macro!();
     assert_eq!(loc2.file(), file!());
-    assert_eq!(loc2.line(), 17);
+    assert_eq!(loc2.line(), 23);
     assert_eq!(loc2.column(), 16);
 }
diff --git a/src/test/ui/rfc-2091-track-caller/const-caller-location.rs b/src/test/ui/rfc-2091-track-caller/const-caller-location.rs
new file mode 100644
index 0000000..0614c52
--- /dev/null
+++ b/src/test/ui/rfc-2091-track-caller/const-caller-location.rs
@@ -0,0 +1,41 @@
+// run-pass
+
+#![feature(const_fn, track_caller)]
+
+use std::panic::Location;
+
+const LOCATION: &Location = Location::caller();
+
+const TRACKED: &Location = tracked();
+#[track_caller]
+const fn tracked() -> &'static Location <'static>