Auto merge of #62094 - oli-obk:zst_intern, r=eddyb
Don't ICE on mutable zst slices
fixes #62045
diff --git a/src/librustc_mir/interpret/intern.rs b/src/librustc_mir/interpret/intern.rs
index 416b66d..f0d64e2 100644
--- a/src/librustc_mir/interpret/intern.rs
+++ b/src/librustc_mir/interpret/intern.rs
@@ -3,7 +3,6 @@
//! After a const evaluation has computed a value, before we destroy the const evaluator's session
//! memory, we need to extract all memory allocations to the global memory pool so they stay around.
-use rustc::ty::layout::LayoutOf;
use rustc::ty::{Ty, TyCtxt, ParamEnv, self};
use rustc::mir::interpret::{
InterpResult, ErrorHandled,
@@ -143,18 +142,15 @@
// Handle Reference types, as these are the only relocations supported by const eval.
// Raw pointers (and boxes) are handled by the `leftover_relocations` logic.
let ty = mplace.layout.ty;
- if let ty::Ref(_, _, mutability) = ty.sty {
+ if let ty::Ref(_, referenced_ty, mutability) = ty.sty {
let value = self.ecx.read_immediate(mplace.into())?;
// Handle trait object vtables
if let Ok(meta) = value.to_meta() {
- let layout = self.ecx.layout_of(ty.builtin_deref(true).unwrap().ty)?;
- if layout.is_unsized() {
- if let ty::Dynamic(..) = self.ecx.tcx.struct_tail(layout.ty).sty {
- if let Ok(vtable) = meta.unwrap().to_ptr() {
- // explitly choose `Immutable` here, since vtables are immutable, even
- // if the reference of the fat pointer is mutable
- self.intern_shallow(vtable, Mutability::Immutable)?;
- }
+ if let ty::Dynamic(..) = self.ecx.tcx.struct_tail(referenced_ty).sty {
+ if let Ok(vtable) = meta.unwrap().to_ptr() {
+ // explitly choose `Immutable` here, since vtables are immutable, even
+ // if the reference of the fat pointer is mutable
+ self.intern_shallow(vtable, Mutability::Immutable)?;
}
}
}
@@ -178,8 +174,14 @@
(InternMode::Static, hir::Mutability::MutMutable) => {},
// we statically prevent `&mut T` via `const_qualif` and double check this here
(InternMode::ConstBase, hir::Mutability::MutMutable) |
- (InternMode::Const, hir::Mutability::MutMutable) =>
- bug!("const qualif failed to prevent mutable references"),
+ (InternMode::Const, hir::Mutability::MutMutable) => {
+ match referenced_ty.sty {
+ ty::Array(_, n) if n.unwrap_usize(self.ecx.tcx.tcx) == 0 => {}
+ ty::Slice(_)
+ if value.to_meta().unwrap().unwrap().to_usize(self.ecx)? == 0 => {}
+ _ => bug!("const qualif failed to prevent mutable references"),
+ }
+ },
}
// Compute the mutability with which we'll start visiting the allocation. This is
// what gets changed when we encounter an `UnsafeCell`
diff --git a/src/test/ui/consts/issue-62045.rs b/src/test/ui/consts/issue-62045.rs
new file mode 100644
index 0000000..9f41ed9
--- /dev/null
+++ b/src/test/ui/consts/issue-62045.rs
@@ -0,0 +1,5 @@
+// compile-pass
+
+fn main() {
+ assert_eq!(&mut [0; 1][..], &mut []);
+}
diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs b/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs
index 4a77534..4fcd89a 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs
+++ b/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs
@@ -3,6 +3,7 @@
// rustc-env:RUST_BACKTRACE=0
// normalize-stderr-test "note: rustc 1.* running on .*" -> "note: rustc VERSION running on TARGET"
// normalize-stderr-test "note: compiler flags: .*" -> "note: compiler flags: FLAGS"
+// normalize-stderr-test "interpret/intern.rs:[0-9]*:[0-9]*" -> "interpret/intern.rs:LL:CC"
#![allow(const_err)]
diff --git a/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr b/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr
index ff2351e..82569e2 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr
+++ b/src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr
@@ -1,12 +1,12 @@
warning: skipping const checks
- --> $DIR/mutable_references_ice.rs:26:9
+ --> $DIR/mutable_references_ice.rs:27:9
|
LL | *MUH.x.get() = 99;
| ^^^^^^^^^^^^^^^^^
thread 'rustc' panicked at 'assertion failed: `(left != right)`
left: `Const`,
- right: `Const`: UnsafeCells are not allowed behind references in constants. This should have been prevented statically by const qualification. If this were allowed one would be able to change a constant at one use site and other use sites may arbitrarily decide to change, too.', src/librustc_mir/interpret/intern.rs:127:17
+ right: `Const`: UnsafeCells are not allowed behind references in constants. This should have been prevented statically by const qualification. If this were allowed one would be able to change a constant at one use site and other use sites may arbitrarily decide to change, too.', src/librustc_mir/interpret/intern.rs:LL:CC
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
error: internal compiler error: unexpected panic
