| #[cfg(bootstrap)] |
| #[doc(include = "panic.md")] |
| #[macro_export] |
| #[allow_internal_unstable(core_panic, track_caller)] |
| #[stable(feature = "core", since = "1.6.0")] |
| macro_rules! panic { |
| () => ( |
| $crate::panic!("explicit panic") |
| ); |
| ($msg:expr) => ( |
| $crate::panicking::panic($msg) |
| ); |
| ($msg:expr,) => ( |
| $crate::panic!($msg) |
| ); |
| ($fmt:expr, $($arg:tt)+) => ( |
| $crate::panicking::panic_fmt( |
| $crate::format_args!($fmt, $($arg)+), |
| $crate::panic::Location::caller(), |
| ) |
| ); |
| } |
| |
| #[cfg(not(bootstrap))] |
| #[doc(include = "panic.md")] |
| #[macro_export] |
| #[allow_internal_unstable(core_panic, track_caller)] |
| #[stable(feature = "core", since = "1.6.0")] |
| macro_rules! panic { |
| () => ( |
| $crate::panic!("explicit panic") |
| ); |
| ($msg:expr) => ( |
| $crate::panicking::panic($msg) |
| ); |
| ($msg:expr,) => ( |
| $crate::panic!($msg) |
| ); |
| ($fmt:expr, $($arg:tt)+) => ( |
| $crate::panicking::panic_fmt($crate::format_args!($fmt, $($arg)+)) |
| ); |
| } |
| |
| /// Asserts that two expressions are equal to each other (using [`PartialEq`]). |
| /// |
| /// On panic, this macro will print the values of the expressions with their |
| /// debug representations. |
| /// |
| /// Like [`assert!`], this macro has a second form, where a custom |
| /// panic message can be provided. |
| /// |
| /// [`PartialEq`]: cmp/trait.PartialEq.html |
| /// [`assert!`]: macro.assert.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let a = 3; |
| /// let b = 1 + 2; |
| /// assert_eq!(a, b); |
| /// |
| /// assert_eq!(a, b, "we are testing addition with {} and {}", a, b); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! assert_eq { |
| ($left:expr, $right:expr) => ({ |
| match (&$left, &$right) { |
| (left_val, right_val) => { |
| if !(*left_val == *right_val) { |
| // The reborrows below are intentional. Without them, the stack slot for the |
| // borrow is initialized even before the values are compared, leading to a |
| // noticeable slow down. |
| panic!(r#"assertion failed: `(left == right)` |
| left: `{:?}`, |
| right: `{:?}`"#, &*left_val, &*right_val) |
| } |
| } |
| } |
| }); |
| ($left:expr, $right:expr,) => ({ |
| $crate::assert_eq!($left, $right) |
| }); |
| ($left:expr, $right:expr, $($arg:tt)+) => ({ |
| match (&($left), &($right)) { |
| (left_val, right_val) => { |
| if !(*left_val == *right_val) { |
| // The reborrows below are intentional. Without them, the stack slot for the |
| // borrow is initialized even before the values are compared, leading to a |
| // noticeable slow down. |
| panic!(r#"assertion failed: `(left == right)` |
| left: `{:?}`, |
| right: `{:?}`: {}"#, &*left_val, &*right_val, |
| $crate::format_args!($($arg)+)) |
| } |
| } |
| } |
| }); |
| } |
| |
| /// Asserts that two expressions are not equal to each other (using [`PartialEq`]). |
| /// |
| /// On panic, this macro will print the values of the expressions with their |
| /// debug representations. |
| /// |
| /// Like [`assert!`], this macro has a second form, where a custom |
| /// panic message can be provided. |
| /// |
| /// [`PartialEq`]: cmp/trait.PartialEq.html |
| /// [`assert!`]: macro.assert.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let a = 3; |
| /// let b = 2; |
| /// assert_ne!(a, b); |
| /// |
| /// assert_ne!(a, b, "we are testing that the values are not equal"); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "assert_ne", since = "1.13.0")] |
| macro_rules! assert_ne { |
| ($left:expr, $right:expr) => ({ |
| match (&$left, &$right) { |
| (left_val, right_val) => { |
| if *left_val == *right_val { |
| // The reborrows below are intentional. Without them, the stack slot for the |
| // borrow is initialized even before the values are compared, leading to a |
| // noticeable slow down. |
| panic!(r#"assertion failed: `(left != right)` |
| left: `{:?}`, |
| right: `{:?}`"#, &*left_val, &*right_val) |
| } |
| } |
| } |
| }); |
| ($left:expr, $right:expr,) => { |
| $crate::assert_ne!($left, $right) |
| }; |
| ($left:expr, $right:expr, $($arg:tt)+) => ({ |
| match (&($left), &($right)) { |
| (left_val, right_val) => { |
| if *left_val == *right_val { |
| // The reborrows below are intentional. Without them, the stack slot for the |
| // borrow is initialized even before the values are compared, leading to a |
| // noticeable slow down. |
| panic!(r#"assertion failed: `(left != right)` |
| left: `{:?}`, |
| right: `{:?}`: {}"#, &*left_val, &*right_val, |
| $crate::format_args!($($arg)+)) |
| } |
| } |
| } |
| }); |
| } |
| |
| /// Asserts that a boolean expression is `true` at runtime. |
| /// |
| /// This will invoke the [`panic!`] macro if the provided expression cannot be |
| /// evaluated to `true` at runtime. |
| /// |
| /// Like [`assert!`], this macro also has a second version, where a custom panic |
| /// message can be provided. |
| /// |
| /// # Uses |
| /// |
| /// Unlike [`assert!`], `debug_assert!` statements are only enabled in non |
| /// optimized builds by default. An optimized build will not execute |
| /// `debug_assert!` statements unless `-C debug-assertions` is passed to the |
| /// compiler. This makes `debug_assert!` useful for checks that are too |
| /// expensive to be present in a release build but may be helpful during |
| /// development. The result of expanding `debug_assert!` is always type checked. |
| /// |
| /// An unchecked assertion allows a program in an inconsistent state to keep |
| /// running, which might have unexpected consequences but does not introduce |
| /// unsafety as long as this only happens in safe code. The performance cost |
| /// of assertions, is however, not measurable in general. Replacing [`assert!`] |
| /// with `debug_assert!` is thus only encouraged after thorough profiling, and |
| /// more importantly, only in safe code! |
| /// |
| /// [`panic!`]: macro.panic.html |
| /// [`assert!`]: macro.assert.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// // the panic message for these assertions is the stringified value of the |
| /// // expression given. |
| /// debug_assert!(true); |
| /// |
| /// fn some_expensive_computation() -> bool { true } // a very simple function |
| /// debug_assert!(some_expensive_computation()); |
| /// |
| /// // assert with a custom message |
| /// let x = true; |
| /// debug_assert!(x, "x wasn't true!"); |
| /// |
| /// let a = 3; let b = 27; |
| /// debug_assert!(a + b == 30, "a = {}, b = {}", a, b); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! debug_assert { |
| ($($arg:tt)*) => (if $crate::cfg!(debug_assertions) { $crate::assert!($($arg)*); }) |
| } |
| |
| /// Asserts that two expressions are equal to each other. |
| /// |
| /// On panic, this macro will print the values of the expressions with their |
| /// debug representations. |
| /// |
| /// Unlike [`assert_eq!`], `debug_assert_eq!` statements are only enabled in non |
| /// optimized builds by default. An optimized build will not execute |
| /// `debug_assert_eq!` statements unless `-C debug-assertions` is passed to the |
| /// compiler. This makes `debug_assert_eq!` useful for checks that are too |
| /// expensive to be present in a release build but may be helpful during |
| /// development. The result of expanding `debug_assert_eq!` is always type checked. |
| /// |
| /// [`assert_eq!`]: ../std/macro.assert_eq.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let a = 3; |
| /// let b = 1 + 2; |
| /// debug_assert_eq!(a, b); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! debug_assert_eq { |
| ($($arg:tt)*) => (if $crate::cfg!(debug_assertions) { $crate::assert_eq!($($arg)*); }) |
| } |
| |
| /// Asserts that two expressions are not equal to each other. |
| /// |
| /// On panic, this macro will print the values of the expressions with their |
| /// debug representations. |
| /// |
| /// Unlike [`assert_ne!`], `debug_assert_ne!` statements are only enabled in non |
| /// optimized builds by default. An optimized build will not execute |
| /// `debug_assert_ne!` statements unless `-C debug-assertions` is passed to the |
| /// compiler. This makes `debug_assert_ne!` useful for checks that are too |
| /// expensive to be present in a release build but may be helpful during |
| /// development. The result of expanding `debug_assert_ne!` is always type checked. |
| /// |
| /// [`assert_ne!`]: ../std/macro.assert_ne.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let a = 3; |
| /// let b = 2; |
| /// debug_assert_ne!(a, b); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "assert_ne", since = "1.13.0")] |
| macro_rules! debug_assert_ne { |
| ($($arg:tt)*) => (if $crate::cfg!(debug_assertions) { $crate::assert_ne!($($arg)*); }) |
| } |
| |
| /// Returns whether the given expression matches any of the given patterns. |
| /// |
| /// Like in a `match` expression, the pattern can be optionally followed by `if` |
| /// and a guard expression that has access to names bound by the pattern. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let foo = 'f'; |
| /// assert!(matches!(foo, 'A'..='Z' | 'a'..='z')); |
| /// |
| /// let bar = Some(4); |
| /// assert!(matches!(bar, Some(x) if x > 2)); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "matches_macro", since = "1.42.0")] |
| macro_rules! matches { |
| ($expression:expr, $( $pattern:pat )|+ $( if $guard: expr )?) => { |
| match $expression { |
| $( $pattern )|+ $( if $guard )? => true, |
| _ => false |
| } |
| } |
| } |
| |
| /// Unwraps a result or propagates its error. |
| /// |
| /// The `?` operator was added to replace `try!` and should be used instead. |
| /// Furthermore, `try` is a reserved word in Rust 2018, so if you must use |
| /// it, you will need to use the [raw-identifier syntax][ris]: `r#try`. |
| /// |
| /// [ris]: https://doc.rust-lang.org/nightly/rust-by-example/compatibility/raw_identifiers.html |
| /// |
| /// `try!` matches the given [`Result`]. In case of the `Ok` variant, the |
| /// expression has the value of the wrapped value. |
| /// |
| /// In case of the `Err` variant, it retrieves the inner error. `try!` then |
| /// performs conversion using `From`. This provides automatic conversion |
| /// between specialized errors and more general ones. The resulting |
| /// error is then immediately returned. |
| /// |
| /// Because of the early return, `try!` can only be used in functions that |
| /// return [`Result`]. |
| /// |
| /// [`Result`]: ../std/result/enum.Result.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io; |
| /// use std::fs::File; |
| /// use std::io::prelude::*; |
| /// |
| /// enum MyError { |
| /// FileWriteError |
| /// } |
| /// |
| /// impl From<io::Error> for MyError { |
| /// fn from(e: io::Error) -> MyError { |
| /// MyError::FileWriteError |
| /// } |
| /// } |
| /// |
| /// // The preferred method of quick returning Errors |
| /// fn write_to_file_question() -> Result<(), MyError> { |
| /// let mut file = File::create("my_best_friends.txt")?; |
| /// file.write_all(b"This is a list of my best friends.")?; |
| /// Ok(()) |
| /// } |
| /// |
| /// // The previous method of quick returning Errors |
| /// fn write_to_file_using_try() -> Result<(), MyError> { |
| /// let mut file = r#try!(File::create("my_best_friends.txt")); |
| /// r#try!(file.write_all(b"This is a list of my best friends.")); |
| /// Ok(()) |
| /// } |
| /// |
| /// // This is equivalent to: |
| /// fn write_to_file_using_match() -> Result<(), MyError> { |
| /// let mut file = r#try!(File::create("my_best_friends.txt")); |
| /// match file.write_all(b"This is a list of my best friends.") { |
| /// Ok(v) => v, |
| /// Err(e) => return Err(From::from(e)), |
| /// } |
| /// Ok(()) |
| /// } |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_deprecated(since = "1.39.0", reason = "use the `?` operator instead")] |
| #[doc(alias = "?")] |
| macro_rules! r#try { |
| ($expr:expr) => { |
| match $expr { |
| $crate::result::Result::Ok(val) => val, |
| $crate::result::Result::Err(err) => { |
| return $crate::result::Result::Err($crate::convert::From::from(err)); |
| } |
| } |
| }; |
| ($expr:expr,) => { |
| $crate::r#try!($expr) |
| }; |
| } |
| |
| /// Writes formatted data into a buffer. |
| /// |
| /// This macro accepts a format string, a list of arguments, and a 'writer'. Arguments will be |
| /// formatted according to the specified format string and the result will be passed to the writer. |
| /// The writer may be any value with a `write_fmt` method; generally this comes from an |
| /// implementation of either the [`std::fmt::Write`] or the [`std::io::Write`] trait. The macro |
| /// returns whatever the `write_fmt` method returns; commonly a [`std::fmt::Result`], or an |
| /// [`io::Result`]. |
| /// |
| /// See [`std::fmt`] for more information on the format string syntax. |
| /// |
| /// [`std::fmt`]: ../std/fmt/index.html |
| /// [`std::fmt::Write`]: ../std/fmt/trait.Write.html |
| /// [`std::io::Write`]: ../std/io/trait.Write.html |
| /// [`std::fmt::Result`]: ../std/fmt/type.Result.html |
| /// [`io::Result`]: ../std/io/type.Result.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io::Write; |
| /// |
| /// fn main() -> std::io::Result<()> { |
| /// let mut w = Vec::new(); |
| /// write!(&mut w, "test")?; |
| /// write!(&mut w, "formatted {}", "arguments")?; |
| /// |
| /// assert_eq!(w, b"testformatted arguments"); |
| /// Ok(()) |
| /// } |
| /// ``` |
| /// |
| /// A module can import both `std::fmt::Write` and `std::io::Write` and call `write!` on objects |
| /// implementing either, as objects do not typically implement both. However, the module must |
| /// import the traits qualified so their names do not conflict: |
| /// |
| /// ``` |
| /// use std::fmt::Write as FmtWrite; |
| /// use std::io::Write as IoWrite; |
| /// |
| /// fn main() -> Result<(), Box<dyn std::error::Error>> { |
| /// let mut s = String::new(); |
| /// let mut v = Vec::new(); |
| /// |
| /// write!(&mut s, "{} {}", "abc", 123)?; // uses fmt::Write::write_fmt |
| /// write!(&mut v, "s = {:?}", s)?; // uses io::Write::write_fmt |
| /// assert_eq!(v, b"s = \"abc 123\""); |
| /// Ok(()) |
| /// } |
| /// ``` |
| /// |
| /// Note: This macro can be used in `no_std` setups as well. |
| /// In a `no_std` setup you are responsible for the implementation details of the components. |
| /// |
| /// ```no_run |
| /// # extern crate core; |
| /// use core::fmt::Write; |
| /// |
| /// struct Example; |
| /// |
| /// impl Write for Example { |
| /// fn write_str(&mut self, _s: &str) -> core::fmt::Result { |
| /// unimplemented!(); |
| /// } |
| /// } |
| /// |
| /// let mut m = Example{}; |
| /// write!(&mut m, "Hello World").expect("Not written"); |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! write { |
| ($dst:expr, $($arg:tt)*) => ($dst.write_fmt($crate::format_args!($($arg)*))) |
| } |
| |
| /// Write formatted data into a buffer, with a newline appended. |
| /// |
| /// On all platforms, the newline is the LINE FEED character (`\n`/`U+000A`) alone |
| /// (no additional CARRIAGE RETURN (`\r`/`U+000D`). |
| /// |
| /// For more information, see [`write!`]. For information on the format string syntax, see |
| /// [`std::fmt`]. |
| /// |
| /// [`write!`]: macro.write.html |
| /// [`std::fmt`]: ../std/fmt/index.html |
| /// |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io::{Write, Result}; |
| /// |
| /// fn main() -> Result<()> { |
| /// let mut w = Vec::new(); |
| /// writeln!(&mut w)?; |
| /// writeln!(&mut w, "test")?; |
| /// writeln!(&mut w, "formatted {}", "arguments")?; |
| /// |
| /// assert_eq!(&w[..], "\ntest\nformatted arguments\n".as_bytes()); |
| /// Ok(()) |
| /// } |
| /// ``` |
| /// |
| /// A module can import both `std::fmt::Write` and `std::io::Write` and call `write!` on objects |
| /// implementing either, as objects do not typically implement both. However, the module must |
| /// import the traits qualified so their names do not conflict: |
| /// |
| /// ``` |
| /// use std::fmt::Write as FmtWrite; |
| /// use std::io::Write as IoWrite; |
| /// |
| /// fn main() -> Result<(), Box<dyn std::error::Error>> { |
| /// let mut s = String::new(); |
| /// let mut v = Vec::new(); |
| /// |
| /// writeln!(&mut s, "{} {}", "abc", 123)?; // uses fmt::Write::write_fmt |
| /// writeln!(&mut v, "s = {:?}", s)?; // uses io::Write::write_fmt |
| /// assert_eq!(v, b"s = \"abc 123\\n\"\n"); |
| /// Ok(()) |
| /// } |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[allow_internal_unstable(format_args_nl)] |
| macro_rules! writeln { |
| ($dst:expr) => ( |
| $crate::write!($dst, "\n") |
| ); |
| ($dst:expr,) => ( |
| $crate::writeln!($dst) |
| ); |
| ($dst:expr, $($arg:tt)*) => ( |
| $dst.write_fmt($crate::format_args_nl!($($arg)*)) |
| ); |
| } |
| |
| /// Indicates unreachable code. |
| /// |
| /// This is useful any time that the compiler can't determine that some code is unreachable. For |
| /// example: |
| /// |
| /// * Match arms with guard conditions. |
| /// * Loops that dynamically terminate. |
| /// * Iterators that dynamically terminate. |
| /// |
| /// If the determination that the code is unreachable proves incorrect, the |
| /// program immediately terminates with a [`panic!`]. |
| /// |
| /// The unsafe counterpart of this macro is the [`unreachable_unchecked`] function, which |
| /// will cause undefined behavior if the code is reached. |
| /// |
| /// [`panic!`]: ../std/macro.panic.html |
| /// [`unreachable_unchecked`]: ../std/hint/fn.unreachable_unchecked.html |
| /// [`std::hint`]: ../std/hint/index.html |
| /// |
| /// # Panics |
| /// |
| /// This will always [`panic!`] |
| /// |
| /// [`panic!`]: ../std/macro.panic.html |
| /// |
| /// # Examples |
| /// |
| /// Match arms: |
| /// |
| /// ``` |
| /// # #[allow(dead_code)] |
| /// fn foo(x: Option<i32>) { |
| /// match x { |
| /// Some(n) if n >= 0 => println!("Some(Non-negative)"), |
| /// Some(n) if n < 0 => println!("Some(Negative)"), |
| /// Some(_) => unreachable!(), // compile error if commented out |
| /// None => println!("None") |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Iterators: |
| /// |
| /// ``` |
| /// # #[allow(dead_code)] |
| /// fn divide_by_three(x: u32) -> u32 { // one of the poorest implementations of x/3 |
| /// for i in 0.. { |
| /// if 3*i < i { panic!("u32 overflow"); } |
| /// if x < 3*i { return i-1; } |
| /// } |
| /// unreachable!(); |
| /// } |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! unreachable { |
| () => ({ |
| panic!("internal error: entered unreachable code") |
| }); |
| ($msg:expr) => ({ |
| $crate::unreachable!("{}", $msg) |
| }); |
| ($msg:expr,) => ({ |
| $crate::unreachable!($msg) |
| }); |
| ($fmt:expr, $($arg:tt)*) => ({ |
| panic!($crate::concat!("internal error: entered unreachable code: ", $fmt), $($arg)*) |
| }); |
| } |
| |
| /// Indicates unimplemented code by panicking with a message of "not implemented". |
| /// |
| /// This allows your code to type-check, which is useful if you are prototyping or |
| /// implementing a trait that requires multiple methods which you don't plan of using all of. |
| /// |
| /// The difference between `unimplemented!` and [`todo!`](macro.todo.html) is that while `todo!` |
| /// conveys an intent of implementing the functionality later and the message is "not yet |
| /// implemented", `unimplemented!` makes no such claims. Its message is "not implemented". |
| /// Also some IDEs will mark `todo!`s. |
| /// |
| /// # Panics |
| /// |
| /// This will always [panic!](macro.panic.html) because `unimplemented!` is just a |
| /// shorthand for `panic!` with a fixed, specific message. |
| /// |
| /// Like `panic!`, this macro has a second form for displaying custom values. |
| /// |
| /// # Examples |
| /// |
| /// Say we have a trait `Foo`: |
| /// |
| /// ``` |
| /// trait Foo { |
| /// fn bar(&self) -> u8; |
| /// fn baz(&self); |
| /// fn qux(&self) -> Result<u64, ()>; |
| /// } |
| /// ``` |
| /// |
| /// We want to implement `Foo` for 'MyStruct', but for some reason it only makes sense |
| /// to implement the `bar()` function. `baz()` and `qux()` will still need to be defined |
| /// in our implementation of `Foo`, but we can use `unimplemented!` in their definitions |
| /// to allow our code to compile. |
| /// |
| /// We still want to have our program stop running if the unimplemented methods are |
| /// reached. |
| /// |
| /// ``` |
| /// # trait Foo { |
| /// # fn bar(&self) -> u8; |
| /// # fn baz(&self); |
| /// # fn qux(&self) -> Result<u64, ()>; |
| /// # } |
| /// struct MyStruct; |
| /// |
| /// impl Foo for MyStruct { |
| /// fn bar(&self) -> u8 { |
| /// 1 + 1 |
| /// } |
| /// |
| /// fn baz(&self) { |
| /// // It makes no sense to `baz` a `MyStruct`, so we have no logic here |
| /// // at all. |
| /// // This will display "thread 'main' panicked at 'not implemented'". |
| /// unimplemented!(); |
| /// } |
| /// |
| /// fn qux(&self) -> Result<u64, ()> { |
| /// // We have some logic here, |
| /// // We can add a message to unimplemented! to display our omission. |
| /// // This will display: |
| /// // "thread 'main' panicked at 'not implemented: MyStruct isn't quxable'". |
| /// unimplemented!("MyStruct isn't quxable"); |
| /// } |
| /// } |
| /// |
| /// fn main() { |
| /// let s = MyStruct; |
| /// s.bar(); |
| /// } |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| macro_rules! unimplemented { |
| () => (panic!("not implemented")); |
| ($($arg:tt)+) => (panic!("not implemented: {}", $crate::format_args!($($arg)+))); |
| } |
| |
| /// Indicates unfinished code. |
| /// |
| /// This can be useful if you are prototyping and are just looking to have your |
| /// code typecheck. |
| /// |
| /// The difference between [`unimplemented!`] and `todo!` is that while `todo!` conveys |
| /// an intent of implementing the functionality later and the message is "not yet |
| /// implemented", `unimplemented!` makes no such claims. Its message is "not implemented". |
| /// Also some IDEs will mark `todo!`s. |
| /// |
| /// [`unimplemented!`]: macro.unimplemented.html |
| /// |
| /// # Panics |
| /// |
| /// This will always [panic!](macro.panic.html) |
| /// |
| /// # Examples |
| /// |
| /// Here's an example of some in-progress code. We have a trait `Foo`: |
| /// |
| /// ``` |
| /// trait Foo { |
| /// fn bar(&self); |
| /// fn baz(&self); |
| /// } |
| /// ``` |
| /// |
| /// We want to implement `Foo` on one of our types, but we also want to work on |
| /// just `bar()` first. In order for our code to compile, we need to implement |
| /// `baz()`, so we can use `todo!`: |
| /// |
| /// ``` |
| /// # trait Foo { |
| /// # fn bar(&self); |
| /// # fn baz(&self); |
| /// # } |
| /// struct MyStruct; |
| /// |
| /// impl Foo for MyStruct { |
| /// fn bar(&self) { |
| /// // implementation goes here |
| /// } |
| /// |
| /// fn baz(&self) { |
| /// // let's not worry about implementing baz() for now |
| /// todo!(); |
| /// } |
| /// } |
| /// |
| /// fn main() { |
| /// let s = MyStruct; |
| /// s.bar(); |
| /// |
| /// // we aren't even using baz(), so this is fine. |
| /// } |
| /// ``` |
| #[macro_export] |
| #[stable(feature = "todo_macro", since = "1.40.0")] |
| macro_rules! todo { |
| () => (panic!("not yet implemented")); |
| ($($arg:tt)+) => (panic!("not yet implemented: {}", $crate::format_args!($($arg)+))); |
| } |
| |
| /// Definitions of built-in macros. |
| /// |
| /// Most of the macro properties (stability, visibility, etc.) are taken from the source code here, |
| /// with exception of expansion functions transforming macro inputs into outputs, |
| /// those functions are provided by the compiler. |
| pub(crate) mod builtin { |
| |
| /// Causes compilation to fail with the given error message when encountered. |
| /// |
| /// This macro should be used when a crate uses a conditional compilation strategy to provide |
| /// better error messages for erroneous conditions. It's the compiler-level form of [`panic!`], |
| /// but emits an error during *compilation* rather than at *runtime*. |
| /// |
| /// # Examples |
| /// |
| /// Two such examples are macros and `#[cfg]` environments. |
| /// |
| /// Emit better compiler error if a macro is passed invalid values. Without the final branch, |
| /// the compiler would still emit an error, but the error's message would not mention the two |
| /// valid values. |
| /// |
| /// ```compile_fail |
| /// macro_rules! give_me_foo_or_bar { |
| /// (foo) => {}; |
| /// (bar) => {}; |
| /// ($x:ident) => { |
| /// compile_error!("This macro only accepts `foo` or `bar`"); |
| /// } |
| /// } |
| /// |
| /// give_me_foo_or_bar!(neither); |
| /// // ^ will fail at compile time with message "This macro only accepts `foo` or `bar`" |
| /// ``` |
| /// |
| /// Emit compiler error if one of a number of features isn't available. |
| /// |
| /// ```compile_fail |
| /// #[cfg(not(any(feature = "foo", feature = "bar")))] |
| /// compile_error!("Either feature \"foo\" or \"bar\" must be enabled for this crate."); |
| /// ``` |
| /// |
| /// [`panic!`]: ../std/macro.panic.html |
| #[stable(feature = "compile_error_macro", since = "1.20.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! compile_error { |
| ($msg:expr) => {{ /* compiler built-in */ }}; |
| ($msg:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Constructs parameters for the other string-formatting macros. |
| /// |
| /// This macro functions by taking a formatting string literal containing |
| /// `{}` for each additional argument passed. `format_args!` prepares the |
| /// additional parameters to ensure the output can be interpreted as a string |
| /// and canonicalizes the arguments into a single type. Any value that implements |
| /// the [`Display`] trait can be passed to `format_args!`, as can any |
| /// [`Debug`] implementation be passed to a `{:?}` within the formatting string. |
| /// |
| /// This macro produces a value of type [`fmt::Arguments`]. This value can be |
| /// passed to the macros within [`std::fmt`] for performing useful redirection. |
| /// All other formatting macros ([`format!`], [`write!`], [`println!`], etc) are |
| /// proxied through this one. `format_args!`, unlike its derived macros, avoids |
| /// heap allocations. |
| /// |
| /// You can use the [`fmt::Arguments`] value that `format_args!` returns |
| /// in `Debug` and `Display` contexts as seen below. The example also shows |
| /// that `Debug` and `Display` format to the same thing: the interpolated |
| /// format string in `format_args!`. |
| /// |
| /// ```rust |
| /// let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2)); |
| /// let display = format!("{}", format_args!("{} foo {:?}", 1, 2)); |
| /// assert_eq!("1 foo 2", display); |
| /// assert_eq!(display, debug); |
| /// ``` |
| /// |
| /// For more information, see the documentation in [`std::fmt`]. |
| /// |
| /// [`Display`]: ../std/fmt/trait.Display.html |
| /// [`Debug`]: ../std/fmt/trait.Debug.html |
| /// [`fmt::Arguments`]: ../std/fmt/struct.Arguments.html |
| /// [`std::fmt`]: ../std/fmt/index.html |
| /// [`format!`]: ../std/macro.format.html |
| /// [`write!`]: ../std/macro.write.html |
| /// [`println!`]: ../std/macro.println.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::fmt; |
| /// |
| /// let s = fmt::format(format_args!("hello {}", "world")); |
| /// assert_eq!(s, format!("hello {}", "world")); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[allow_internal_unstable(fmt_internals)] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! format_args { |
| ($fmt:expr) => {{ /* compiler built-in */ }}; |
| ($fmt:expr, $($args:tt)*) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Same as `format_args`, but adds a newline in the end. |
| #[unstable( |
| feature = "format_args_nl", |
| issue = "none", |
| reason = "`format_args_nl` is only for internal \ |
| language use and is subject to change" |
| )] |
| #[allow_internal_unstable(fmt_internals)] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! format_args_nl { |
| ($fmt:expr) => {{ /* compiler built-in */ }}; |
| ($fmt:expr, $($args:tt)*) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Inspects an environment variable at compile time. |
| /// |
| /// This macro will expand to the value of the named environment variable at |
| /// compile time, yielding an expression of type `&'static str`. |
| /// |
| /// If the environment variable is not defined, then a compilation error |
| /// will be emitted. To not emit a compile error, use the [`option_env!`] |
| /// macro instead. |
| /// |
| /// [`option_env!`]: ../std/macro.option_env.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let path: &'static str = env!("PATH"); |
| /// println!("the $PATH variable at the time of compiling was: {}", path); |
| /// ``` |
| /// |
| /// You can customize the error message by passing a string as the second |
| /// parameter: |
| /// |
| /// ```compile_fail |
| /// let doc: &'static str = env!("documentation", "what's that?!"); |
| /// ``` |
| /// |
| /// If the `documentation` environment variable is not defined, you'll get |
| /// the following error: |
| /// |
| /// ```text |
| /// error: what's that?! |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! env { |
| ($name:expr) => {{ /* compiler built-in */ }}; |
| ($name:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Optionally inspects an environment variable at compile time. |
| /// |
| /// If the named environment variable is present at compile time, this will |
| /// expand into an expression of type `Option<&'static str>` whose value is |
| /// `Some` of the value of the environment variable. If the environment |
| /// variable is not present, then this will expand to `None`. See |
| /// [`Option<T>`][option] for more information on this type. |
| /// |
| /// A compile time error is never emitted when using this macro regardless |
| /// of whether the environment variable is present or not. |
| /// |
| /// [option]: ../std/option/enum.Option.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let key: Option<&'static str> = option_env!("SECRET_KEY"); |
| /// println!("the secret key might be: {:?}", key); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! option_env { |
| ($name:expr) => {{ /* compiler built-in */ }}; |
| ($name:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Concatenates identifiers into one identifier. |
| /// |
| /// This macro takes any number of comma-separated identifiers, and |
| /// concatenates them all into one, yielding an expression which is a new |
| /// identifier. Note that hygiene makes it such that this macro cannot |
| /// capture local variables. Also, as a general rule, macros are only |
| /// allowed in item, statement or expression position. That means while |
| /// you may use this macro for referring to existing variables, functions or |
| /// modules etc, you cannot define a new one with it. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(concat_idents)] |
| /// |
| /// # fn main() { |
| /// fn foobar() -> u32 { 23 } |
| /// |
| /// let f = concat_idents!(foo, bar); |
| /// println!("{}", f()); |
| /// |
| /// // fn concat_idents!(new, fun, name) { } // not usable in this way! |
| /// # } |
| /// ``` |
| #[unstable( |
| feature = "concat_idents", |
| issue = "29599", |
| reason = "`concat_idents` is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! concat_idents { |
| ($($e:ident),+) => {{ /* compiler built-in */ }}; |
| ($($e:ident,)+) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Concatenates literals into a static string slice. |
| /// |
| /// This macro takes any number of comma-separated literals, yielding an |
| /// expression of type `&'static str` which represents all of the literals |
| /// concatenated left-to-right. |
| /// |
| /// Integer and floating point literals are stringified in order to be |
| /// concatenated. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let s = concat!("test", 10, 'b', true); |
| /// assert_eq!(s, "test10btrue"); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! concat { |
| ($($e:expr),*) => {{ /* compiler built-in */ }}; |
| ($($e:expr,)*) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Expands to the line number on which it was invoked. |
| /// |
| /// With [`column!`] and [`file!`], these macros provide debugging information for |
| /// developers about the location within the source. |
| /// |
| /// The expanded expression has type `u32` and is 1-based, so the first line |
| /// in each file evaluates to 1, the second to 2, etc. This is consistent |
| /// with error messages by common compilers or popular editors. |
| /// The returned line is *not necessarily* the line of the `line!` invocation itself, |
| /// but rather the first macro invocation leading up to the invocation |
| /// of the `line!` macro. |
| /// |
| /// [`column!`]: macro.column.html |
| /// [`file!`]: macro.file.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let current_line = line!(); |
| /// println!("defined on line: {}", current_line); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! line { |
| () => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Expands to the column number at which it was invoked. |
| /// |
| /// With [`line!`] and [`file!`], these macros provide debugging information for |
| /// developers about the location within the source. |
| /// |
| /// The expanded expression has type `u32` and is 1-based, so the first column |
| /// in each line evaluates to 1, the second to 2, etc. This is consistent |
| /// with error messages by common compilers or popular editors. |
| /// The returned column is *not necessarily* the line of the `column!` invocation itself, |
| /// but rather the first macro invocation leading up to the invocation |
| /// of the `column!` macro. |
| /// |
| /// [`line!`]: macro.line.html |
| /// [`file!`]: macro.file.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let current_col = column!(); |
| /// println!("defined on column: {}", current_col); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! column { |
| () => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Expands to the file name in which it was invoked. |
| /// |
| /// With [`line!`] and [`column!`], these macros provide debugging information for |
| /// developers about the location within the source. |
| /// |
| /// |
| /// The expanded expression has type `&'static str`, and the returned file |
| /// is not the invocation of the `file!` macro itself, but rather the |
| /// first macro invocation leading up to the invocation of the `file!` |
| /// macro. |
| /// |
| /// [`line!`]: macro.line.html |
| /// [`column!`]: macro.column.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let this_file = file!(); |
| /// println!("defined in file: {}", this_file); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! file { |
| () => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Stringifies its arguments. |
| /// |
| /// This macro will yield an expression of type `&'static str` which is the |
| /// stringification of all the tokens passed to the macro. No restrictions |
| /// are placed on the syntax of the macro invocation itself. |
| /// |
| /// Note that the expanded results of the input tokens may change in the |
| /// future. You should be careful if you rely on the output. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let one_plus_one = stringify!(1 + 1); |
| /// assert_eq!(one_plus_one, "1 + 1"); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! stringify { |
| ($($t:tt)*) => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Includes a utf8-encoded file as a string. |
| /// |
| /// The file is located relative to the current file. (similarly to how |
| /// modules are found) |
| /// |
| /// This macro will yield an expression of type `&'static str` which is the |
| /// contents of the file. |
| /// |
| /// # Examples |
| /// |
| /// Assume there are two files in the same directory with the following |
| /// contents: |
| /// |
| /// File 'spanish.in': |
| /// |
| /// ```text |
| /// adiós |
| /// ``` |
| /// |
| /// File 'main.rs': |
| /// |
| /// ```ignore (cannot-doctest-external-file-dependency) |
| /// fn main() { |
| /// let my_str = include_str!("spanish.in"); |
| /// assert_eq!(my_str, "adiós\n"); |
| /// print!("{}", my_str); |
| /// } |
| /// ``` |
| /// |
| /// Compiling 'main.rs' and running the resulting binary will print "adiós". |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! include_str { |
| ($file:expr) => {{ /* compiler built-in */ }}; |
| ($file:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Includes a file as a reference to a byte array. |
| /// |
| /// The file is located relative to the current file. (similarly to how |
| /// modules are found) |
| /// |
| /// This macro will yield an expression of type `&'static [u8; N]` which is |
| /// the contents of the file. |
| /// |
| /// # Examples |
| /// |
| /// Assume there are two files in the same directory with the following |
| /// contents: |
| /// |
| /// File 'spanish.in': |
| /// |
| /// ```text |
| /// adiós |
| /// ``` |
| /// |
| /// File 'main.rs': |
| /// |
| /// ```ignore (cannot-doctest-external-file-dependency) |
| /// fn main() { |
| /// let bytes = include_bytes!("spanish.in"); |
| /// assert_eq!(bytes, b"adi\xc3\xb3s\n"); |
| /// print!("{}", String::from_utf8_lossy(bytes)); |
| /// } |
| /// ``` |
| /// |
| /// Compiling 'main.rs' and running the resulting binary will print "adiós". |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! include_bytes { |
| ($file:expr) => {{ /* compiler built-in */ }}; |
| ($file:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Expands to a string that represents the current module path. |
| /// |
| /// The current module path can be thought of as the hierarchy of modules |
| /// leading back up to the crate root. The first component of the path |
| /// returned is the name of the crate currently being compiled. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// mod test { |
| /// pub fn foo() { |
| /// assert!(module_path!().ends_with("test")); |
| /// } |
| /// } |
| /// |
| /// test::foo(); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! module_path { |
| () => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Evaluates boolean combinations of configuration flags at compile-time. |
| /// |
| /// In addition to the `#[cfg]` attribute, this macro is provided to allow |
| /// boolean expression evaluation of configuration flags. This frequently |
| /// leads to less duplicated code. |
| /// |
| /// The syntax given to this macro is the same syntax as the [`cfg`] |
| /// attribute. |
| /// |
| /// [`cfg`]: ../reference/conditional-compilation.html#the-cfg-attribute |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let my_directory = if cfg!(windows) { |
| /// "windows-specific-directory" |
| /// } else { |
| /// "unix-directory" |
| /// }; |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! cfg { |
| ($($cfg:tt)*) => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Parses a file as an expression or an item according to the context. |
| /// |
| /// The file is located relative to the current file (similarly to how |
| /// modules are found). |
| /// |
| /// Using this macro is often a bad idea, because if the file is |
| /// parsed as an expression, it is going to be placed in the |
| /// surrounding code unhygienically. This could result in variables |
| /// or functions being different from what the file expected if |
| /// there are variables or functions that have the same name in |
| /// the current file. |
| /// |
| /// # Examples |
| /// |
| /// Assume there are two files in the same directory with the following |
| /// contents: |
| /// |
| /// File 'monkeys.in': |
| /// |
| /// ```ignore (only-for-syntax-highlight) |
| /// ['🙈', '🙊', '🙉'] |
| /// .iter() |
| /// .cycle() |
| /// .take(6) |
| /// .collect::<String>() |
| /// ``` |
| /// |
| /// File 'main.rs': |
| /// |
| /// ```ignore (cannot-doctest-external-file-dependency) |
| /// fn main() { |
| /// let my_string = include!("monkeys.in"); |
| /// assert_eq!("🙈🙊🙉🙈🙊🙉", my_string); |
| /// println!("{}", my_string); |
| /// } |
| /// ``` |
| /// |
| /// Compiling 'main.rs' and running the resulting binary will print |
| /// "🙈🙊🙉🙈🙊🙉". |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! include { |
| ($file:expr) => {{ /* compiler built-in */ }}; |
| ($file:expr,) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Asserts that a boolean expression is `true` at runtime. |
| /// |
| /// This will invoke the [`panic!`] macro if the provided expression cannot be |
| /// evaluated to `true` at runtime. |
| /// |
| /// # Uses |
| /// |
| /// Assertions are always checked in both debug and release builds, and cannot |
| /// be disabled. See [`debug_assert!`] for assertions that are not enabled in |
| /// release builds by default. |
| /// |
| /// Unsafe code relies on `assert!` to enforce run-time invariants that, if |
| /// violated could lead to unsafety. |
| /// |
| /// Other use-cases of `assert!` include testing and enforcing run-time |
| /// invariants in safe code (whose violation cannot result in unsafety). |
| /// |
| /// # Custom Messages |
| /// |
| /// This macro has a second form, where a custom panic message can |
| /// be provided with or without arguments for formatting. See [`std::fmt`] |
| /// for syntax for this form. |
| /// |
| /// [`panic!`]: macro.panic.html |
| /// [`debug_assert!`]: macro.debug_assert.html |
| /// [`std::fmt`]: ../std/fmt/index.html |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// // the panic message for these assertions is the stringified value of the |
| /// // expression given. |
| /// assert!(true); |
| /// |
| /// fn some_computation() -> bool { true } // a very simple function |
| /// |
| /// assert!(some_computation()); |
| /// |
| /// // assert with a custom message |
| /// let x = true; |
| /// assert!(x, "x wasn't true!"); |
| /// |
| /// let a = 3; let b = 27; |
| /// assert!(a + b == 30, "a = {}, b = {}", a, b); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! assert { |
| ($cond:expr) => {{ /* compiler built-in */ }}; |
| ($cond:expr,) => {{ /* compiler built-in */ }}; |
| ($cond:expr, $($arg:tt)+) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Inline assembly. |
| /// |
| /// Read the [unstable book] for the usage. |
| /// |
| /// [unstable book]: ../unstable-book/library-features/asm.html |
| #[unstable( |
| feature = "asm", |
| issue = "70173", |
| reason = "inline assembly is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! asm { |
| ("assembly template" |
| : $("output"(operand),)* |
| : $("input"(operand),)* |
| : $("clobbers",)* |
| : $("options",)*) => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Inline assembly. |
| /// |
| /// Read the [unstable book] for the usage. |
| /// |
| /// [unstable book]: ../unstable-book/library-features/asm.html |
| #[cfg(bootstrap)] |
| #[unstable( |
| feature = "llvm_asm", |
| issue = "70173", |
| reason = "inline assembly is not stable enough for use and is subject to change" |
| )] |
| #[macro_export] |
| #[allow_internal_unstable(asm)] |
| macro_rules! llvm_asm { |
| // Redirect to asm! for stage0 |
| ($($arg:tt)*) => { $crate::asm!($($arg)*) } |
| } |
| |
| /// Inline assembly. |
| /// |
| /// Read the [unstable book] for the usage. |
| /// |
| /// [unstable book]: ../unstable-book/library-features/asm.html |
| #[cfg(not(bootstrap))] |
| #[unstable( |
| feature = "llvm_asm", |
| issue = "70173", |
| reason = "inline assembly is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! llvm_asm { |
| ("assembly template" |
| : $("output"(operand),)* |
| : $("input"(operand),)* |
| : $("clobbers",)* |
| : $("options",)*) => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Module-level inline assembly. |
| #[unstable( |
| feature = "global_asm", |
| issue = "35119", |
| reason = "`global_asm!` is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! global_asm { |
| ("assembly") => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Prints passed tokens into the standard output. |
| #[unstable( |
| feature = "log_syntax", |
| issue = "29598", |
| reason = "`log_syntax!` is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! log_syntax { |
| ($($arg:tt)*) => { |
| /* compiler built-in */ |
| }; |
| } |
| |
| /// Enables or disables tracing functionality used for debugging other macros. |
| #[unstable( |
| feature = "trace_macros", |
| issue = "29598", |
| reason = "`trace_macros` is not stable enough for use and is subject to change" |
| )] |
| #[rustc_builtin_macro] |
| #[macro_export] |
| macro_rules! trace_macros { |
| (true) => {{ /* compiler built-in */ }}; |
| (false) => {{ /* compiler built-in */ }}; |
| } |
| |
| /// Attribute macro applied to a function to turn it into a unit test. |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[allow_internal_unstable(test, rustc_attrs)] |
| #[rustc_builtin_macro] |
| pub macro test($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// Attribute macro applied to a function to turn it into a benchmark test. |
| #[unstable( |
| feature = "test", |
| issue = "50297", |
| soft, |
| reason = "`bench` is a part of custom test frameworks which are unstable" |
| )] |
| #[allow_internal_unstable(test, rustc_attrs)] |
| #[rustc_builtin_macro] |
| pub macro bench($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// An implementation detail of the `#[test]` and `#[bench]` macros. |
| #[unstable( |
| feature = "custom_test_frameworks", |
| issue = "50297", |
| reason = "custom test frameworks are an unstable feature" |
| )] |
| #[allow_internal_unstable(test, rustc_attrs)] |
| #[rustc_builtin_macro] |
| pub macro test_case($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// Attribute macro applied to a static to register it as a global allocator. |
| #[stable(feature = "global_allocator", since = "1.28.0")] |
| #[allow_internal_unstable(rustc_attrs)] |
| #[rustc_builtin_macro] |
| pub macro global_allocator($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// Keeps the item it's applied to if the passed path is accessible, and removes it otherwise. |
| #[cfg(not(bootstrap))] |
| #[unstable( |
| feature = "cfg_accessible", |
| issue = "64797", |
| reason = "`cfg_accessible` is not fully implemented" |
| )] |
| #[rustc_builtin_macro] |
| pub macro cfg_accessible($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// Unstable implementation detail of the `rustc` compiler, do not use. |
| #[rustc_builtin_macro] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[allow_internal_unstable(core_intrinsics, libstd_sys_internals)] |
| pub macro RustcDecodable($item:item) { |
| /* compiler built-in */ |
| } |
| |
| /// Unstable implementation detail of the `rustc` compiler, do not use. |
| #[rustc_builtin_macro] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[allow_internal_unstable(core_intrinsics)] |
| pub macro RustcEncodable($item:item) { |
| /* compiler built-in */ |
| } |
| } |