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Diffstat (limited to 'library/core/src/macros/mod.rs')
| -rw-r--r-- | library/core/src/macros/mod.rs | 1554 |
1 files changed, 1554 insertions, 0 deletions
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs new file mode 100644 index 000000000..3a115a8b8 --- /dev/null +++ b/library/core/src/macros/mod.rs @@ -0,0 +1,1554 @@ +#[doc = include_str!("panic.md")] +#[macro_export] +#[rustc_builtin_macro(core_panic)] +#[allow_internal_unstable(edition_panic)] +#[stable(feature = "core", since = "1.6.0")] +#[rustc_diagnostic_item = "core_panic_macro"] +macro_rules! panic { + // Expands to either `$crate::panic::panic_2015` or `$crate::panic::panic_2021` + // depending on the edition of the caller. + ($($arg:tt)*) => { + /* compiler built-in */ + }; +} + +/// 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. +/// +/// # 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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "assert_eq_macro")] +#[allow_internal_unstable(core_panic)] +macro_rules! assert_eq { + ($left:expr, $right:expr $(,)?) => { + match (&$left, &$right) { + (left_val, right_val) => { + if !(*left_val == *right_val) { + let kind = $crate::panicking::AssertKind::Eq; + // 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. + $crate::panicking::assert_failed(kind, &*left_val, &*right_val, $crate::option::Option::None); + } + } + } + }; + ($left:expr, $right:expr, $($arg:tt)+) => { + match (&$left, &$right) { + (left_val, right_val) => { + if !(*left_val == *right_val) { + let kind = $crate::panicking::AssertKind::Eq; + // 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. + $crate::panicking::assert_failed(kind, &*left_val, &*right_val, $crate::option::Option::Some($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. +/// +/// # 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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "assert_ne_macro")] +#[allow_internal_unstable(core_panic)] +macro_rules! assert_ne { + ($left:expr, $right:expr $(,)?) => { + match (&$left, &$right) { + (left_val, right_val) => { + if *left_val == *right_val { + let kind = $crate::panicking::AssertKind::Ne; + // 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. + $crate::panicking::assert_failed(kind, &*left_val, &*right_val, $crate::option::Option::None); + } + } + } + }; + ($left:expr, $right:expr, $($arg:tt)+) => { + match (&($left), &($right)) { + (left_val, right_val) => { + if *left_val == *right_val { + let kind = $crate::panicking::AssertKind::Ne; + // 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. + $crate::panicking::assert_failed(kind, &*left_val, &*right_val, $crate::option::Option::Some($crate::format_args!($($arg)+))); + } + } + } + }; +} + +/// Asserts that an 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. +/// +/// On panic, this macro will print the value of the expression with its +/// debug representation. +/// +/// Like [`assert!`], this macro has a second form, where a custom +/// panic message can be provided. +/// +/// # Examples +/// +/// ``` +/// #![feature(assert_matches)] +/// +/// use std::assert_matches::assert_matches; +/// +/// let a = 1u32.checked_add(2); +/// let b = 1u32.checked_sub(2); +/// assert_matches!(a, Some(_)); +/// assert_matches!(b, None); +/// +/// let c = Ok("abc".to_string()); +/// assert_matches!(c, Ok(x) | Err(x) if x.len() < 100); +/// ``` +#[unstable(feature = "assert_matches", issue = "82775")] +#[allow_internal_unstable(core_panic)] +#[rustc_macro_transparency = "semitransparent"] +pub macro assert_matches { + ($left:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => { + match $left { + $( $pattern )|+ $( if $guard )? => {} + ref left_val => { + $crate::panicking::assert_matches_failed( + left_val, + $crate::stringify!($($pattern)|+ $(if $guard)?), + $crate::option::Option::None + ); + } + } + }, + ($left:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )?, $($arg:tt)+) => { + match $left { + $( $pattern )|+ $( if $guard )? => {} + ref left_val => { + $crate::panicking::assert_matches_failed( + left_val, + $crate::stringify!($($pattern)|+ $(if $guard)?), + $crate::option::Option::Some($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, however, is not measurable in general. Replacing [`assert!`] +/// with `debug_assert!` is thus only encouraged after thorough profiling, and +/// more importantly, only in safe code! +/// +/// # 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")] +#[rustc_diagnostic_item = "debug_assert_macro"] +#[allow_internal_unstable(edition_panic)] +macro_rules! debug_assert { + ($($arg:tt)*) => { + if $crate::cfg!(debug_assertions) { + $crate::assert!($($arg)*); + } + }; +} + +/// Asserts that two expressions are equal to each other. +/// +/// On panic, this macro will print the values of the expressions with their +/// debug representations. +/// +/// Unlike [`assert_eq!`], `debug_assert_eq!` statements are only enabled in non +/// optimized builds by default. An optimized build will not execute +/// `debug_assert_eq!` statements unless `-C debug-assertions` is passed to the +/// compiler. This makes `debug_assert_eq!` useful for checks that are too +/// expensive to be present in a release build but may be helpful during +/// development. The result of expanding `debug_assert_eq!` is always type checked. +/// +/// # Examples +/// +/// ``` +/// let a = 3; +/// let b = 1 + 2; +/// debug_assert_eq!(a, b); +/// ``` +#[macro_export] +#[stable(feature = "rust1", since = "1.0.0")] +#[cfg_attr(not(test), rustc_diagnostic_item = "debug_assert_eq_macro")] +macro_rules! debug_assert_eq { + ($($arg:tt)*) => { + if $crate::cfg!(debug_assertions) { + $crate::assert_eq!($($arg)*); + } + }; +} + +/// Asserts that two expressions are not equal to each other. +/// +/// On panic, this macro will print the values of the expressions with their +/// debug representations. +/// +/// Unlike [`assert_ne!`], `debug_assert_ne!` statements are only enabled in non +/// optimized builds by default. An optimized build will not execute +/// `debug_assert_ne!` statements unless `-C debug-assertions` is passed to the +/// compiler. This makes `debug_assert_ne!` useful for checks that are too +/// expensive to be present in a release build but may be helpful during +/// development. The result of expanding `debug_assert_ne!` is always type checked. +/// +/// # Examples +/// +/// ``` +/// let a = 3; +/// let b = 2; +/// debug_assert_ne!(a, b); +/// ``` +#[macro_export] +#[stable(feature = "assert_ne", since = "1.13.0")] +#[cfg_attr(not(test), rustc_diagnostic_item = "debug_assert_ne_macro")] +macro_rules! debug_assert_ne { + ($($arg:tt)*) => { + if $crate::cfg!(debug_assertions) { + $crate::assert_ne!($($arg)*); + } + }; +} + +/// Asserts that an expression matches any of the given patterns. +/// +/// Like in a `match` expression, the pattern can be optionally followed by `if` +/// and a guard expression that has access to names bound by the pattern. +/// +/// On panic, this macro will print the value of the expression with its +/// debug representation. +/// +/// Unlike [`assert_matches!`], `debug_assert_matches!` statements are only +/// enabled in non optimized builds by default. An optimized build will not +/// execute `debug_assert_matches!` statements unless `-C debug-assertions` is +/// passed to the compiler. This makes `debug_assert_matches!` useful for +/// checks that are too expensive to be present in a release build but may be +/// helpful during development. The result of expanding `debug_assert_matches!` +/// is always type checked. +/// +/// # Examples +/// +/// ``` +/// #![feature(assert_matches)] +/// +/// use std::assert_matches::debug_assert_matches; +/// +/// let a = 1u32.checked_add(2); +/// let b = 1u32.checked_sub(2); +/// debug_assert_matches!(a, Some(_)); +/// debug_assert_matches!(b, None); +/// +/// let c = Ok("abc".to_string()); +/// debug_assert_matches!(c, Ok(x) | Err(x) if x.len() < 100); +/// ``` +#[macro_export] +#[unstable(feature = "assert_matches", issue = "82775")] +#[allow_internal_unstable(assert_matches)] +#[rustc_macro_transparency = "semitransparent"] +pub macro debug_assert_matches($($arg:tt)*) { + if $crate::cfg!(debug_assertions) { + $crate::assert_matches::assert_matches!($($arg)*); + } +} + +/// Returns whether the given expression matches any of the given patterns. +/// +/// Like in a `match` expression, the pattern can be optionally followed by `if` +/// and a guard expression that has access to names bound by the pattern. +/// +/// # Examples +/// +/// ``` +/// let foo = 'f'; +/// assert!(matches!(foo, 'A'..='Z' | 'a'..='z')); +/// +/// let bar = Some(4); +/// assert!(matches!(bar, Some(x) if x > 2)); +/// ``` +#[macro_export] +#[stable(feature = "matches_macro", since = "1.42.0")] +#[cfg_attr(not(test), rustc_diagnostic_item = "matches_macro")] +macro_rules! matches { + ($expression:expr, $(|)? $( $pattern:pat_param )|+ $( 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`]. +/// +/// # 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")] +#[deprecated(since = "1.39.0", note = "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)); + } + } + }; +} + +/// Writes formatted data into a buffer. +/// +/// This macro accepts a 'writer', a format string, and a list of arguments. 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 [`fmt::Write`] or the [`io::Write`] trait. The macro +/// returns whatever the `write_fmt` method returns; commonly a [`fmt::Result`], or an +/// [`io::Result`]. +/// +/// See [`std::fmt`] for more information on the format string syntax. +/// +/// [`std::fmt`]: ../std/fmt/index.html +/// [`fmt::Write`]: crate::fmt::Write +/// [`io::Write`]: ../std/io/trait.Write.html +/// [`fmt::Result`]: crate::fmt::Result +/// [`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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "write_macro")] +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`]. +/// +/// [`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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "writeln_macro")] +#[allow_internal_unstable(format_args_nl)] +macro_rules! writeln { + ($dst:expr $(,)?) => { + $crate::write!($dst, "\n") + }; + ($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. +/// +/// [`unreachable_unchecked`]: crate::hint::unreachable_unchecked +/// +/// # Panics +/// +/// This will always [`panic!`] because `unreachable!` is just a shorthand for `panic!` with a +/// fixed, specific message. +/// +/// Like `panic!`, this macro has a second form for displaying custom values. +/// +/// # 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!("The loop should always return"); +/// } +/// ``` +#[macro_export] +#[rustc_builtin_macro(unreachable)] +#[allow_internal_unstable(edition_panic)] +#[stable(feature = "rust1", since = "1.0.0")] +#[cfg_attr(not(test), rustc_diagnostic_item = "unreachable_macro")] +macro_rules! unreachable { + // Expands to either `$crate::panic::unreachable_2015` or `$crate::panic::unreachable_2021` + // depending on the edition of the caller. + ($($arg:tt)*) => { + /* compiler built-in */ + }; +} + +/// 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 to use all of. +/// +/// 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. +/// +/// # Panics +/// +/// This will always [`panic!`] 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. +/// +/// [`todo!`]: crate::todo +/// +/// # 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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "unimplemented_macro")] +#[allow_internal_unstable(core_panic)] +macro_rules! unimplemented { + () => { + $crate::panicking::panic("not implemented") + }; + ($($arg:tt)+) => { + $crate::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. +/// +/// # Panics +/// +/// This will always [`panic!`]. +/// +/// # 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")] +#[cfg_attr(not(test), rustc_diagnostic_item = "todo_macro")] +#[allow_internal_unstable(core_panic)] +macro_rules! todo { + () => { + $crate::panicking::panic("not yet implemented") + }; + ($($arg:tt)+) => { + $crate::panic!("not yet implemented: {}", $crate::format_args!($($arg)+)) + }; +} + +/// Definitions of built-in macros. +/// +/// Most of the macro properties (stability, visibility, etc.) are taken from the source code here, +/// with exception of expansion functions transforming macro inputs into outputs, +/// those functions are provided by the compiler. +pub(crate) mod builtin { + + /// Causes compilation to fail with the given error message when encountered. + /// + /// This macro should be used when a crate uses a conditional compilation strategy to provide + /// better error messages for erroneous conditions. It's the compiler-level form of [`panic!`], + /// but emits an error during *compilation* rather than at *runtime*. + /// + /// # Examples + /// + /// Two such examples are macros and `#[cfg]` environments. + /// + /// Emit a better compiler error if a macro is passed invalid values. Without the final branch, + /// the compiler would still emit an error, but the error's message would not mention the two + /// valid values. + /// + /// ```compile_fail + /// macro_rules! give_me_foo_or_bar { + /// (foo) => {}; + /// (bar) => {}; + /// ($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 a 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."); + /// ``` + #[stable(feature = "compile_error_macro", since = "1.20.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "compile_error_macro")] + macro_rules! compile_error { + ($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`]: crate::fmt::Display + /// [`Debug`]: crate::fmt::Debug + /// [`fmt::Arguments`]: crate::fmt::Arguments + /// [`std::fmt`]: ../std/fmt/index.html + /// [`format!`]: ../std/macro.format.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")] + #[cfg_attr(not(test), rustc_diagnostic_item = "format_args_macro")] + #[allow_internal_unsafe] + #[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 can be used in some const contexts. + /// + /// This macro is used by the panic macros for the `const_panic` feature. + /// + /// This macro will be removed once `format_args` is allowed in const contexts. + #[unstable(feature = "const_format_args", issue = "none")] + #[allow_internal_unstable(fmt_internals, const_fmt_arguments_new)] + #[rustc_builtin_macro] + #[macro_export] + macro_rules! const_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`. Use + /// [`std::env::var`] instead if you want to read the value at runtime. + /// + /// [`std::env::var`]: ../std/env/fn.var.html + /// + /// 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. + /// + /// # Examples + /// + /// ``` + /// let path: &'static str = env!("PATH"); + /// println!("the $PATH variable at the time of compiling was: {path}"); + /// ``` + /// + /// You can customize the error message by passing a string as the second + /// parameter: + /// + /// ```compile_fail + /// let doc: &'static str = env!("documentation", "what's that?!"); + /// ``` + /// + /// If the `documentation` environment variable is not defined, you'll get + /// the following error: + /// + /// ```text + /// error: what's that?! + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "env_macro")] + macro_rules! env { + ($name:expr $(,)?) => {{ /* compiler built-in */ }}; + ($name:expr, $error_msg:expr $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Optionally inspects an environment variable at compile time. + /// + /// If the named environment variable is present at compile time, this will + /// expand into an expression of type `Option<&'static str>` whose value is + /// `Some` of the value of the environment variable. If the environment + /// variable is not present, then this will expand to `None`. See + /// [`Option<T>`][Option] for more information on this type. Use + /// [`std::env::var`] instead if you want to read the value at runtime. + /// + /// [`std::env::var`]: ../std/env/fn.var.html + /// + /// A compile time error is never emitted when using this macro regardless + /// of whether the environment variable is present or not. + /// + /// # Examples + /// + /// ``` + /// let key: Option<&'static str> = option_env!("SECRET_KEY"); + /// println!("the secret key might be: {key:?}"); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "option_env_macro")] + macro_rules! option_env { + ($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),+ $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Concatenates literals into a byte slice. + /// + /// This macro takes any number of comma-separated literals, and concatenates them all into + /// one, yielding an expression of type `&[u8, _]`, which represents all of the literals + /// concatenated left-to-right. The literals passed can be any combination of: + /// + /// - byte literals (`b'r'`) + /// - byte strings (`b"Rust"`) + /// - arrays of bytes/numbers (`[b'A', 66, b'C']`) + /// + /// # Examples + /// + /// ``` + /// #![feature(concat_bytes)] + /// + /// # fn main() { + /// let s: &[u8; 6] = concat_bytes!(b'A', b"BC", [68, b'E', 70]); + /// assert_eq!(s, b"ABCDEF"); + /// # } + /// ``` + #[unstable(feature = "concat_bytes", issue = "87555")] + #[rustc_builtin_macro] + #[macro_export] + macro_rules! concat_bytes { + ($($e:literal),+ $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Concatenates literals into a static string slice. + /// + /// This macro takes any number of comma-separated literals, yielding an + /// expression of type `&'static str` which represents all of the literals + /// concatenated left-to-right. + /// + /// Integer and floating point literals are stringified in order to be + /// concatenated. + /// + /// # Examples + /// + /// ``` + /// let s = concat!("test", 10, 'b', true); + /// assert_eq!(s, "test10btrue"); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "concat_macro")] + macro_rules! concat { + ($($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. + /// + /// # Examples + /// + /// ``` + /// let current_line = line!(); + /// println!("defined on line: {current_line}"); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "line_macro")] + 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. + /// + /// # Examples + /// + /// ``` + /// let current_col = column!(); + /// println!("defined on column: {current_col}"); + /// ``` + /// + /// `column!` counts Unicode code points, not bytes or graphemes. As a result, the first two + /// invocations return the same value, but the third does not. + /// + /// ``` + /// let a = ("foobar", column!()).1; + /// let b = ("人之初性本善", column!()).1; + /// let c = ("f̅o̅o̅b̅a̅r̅", column!()).1; // Uses combining overline (U+0305) + /// + /// assert_eq!(a, b); + /// assert_ne!(b, c); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "column_macro")] + 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. + /// + /// # Examples + /// + /// ``` + /// let this_file = file!(); + /// println!("defined in file: {this_file}"); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "file_macro")] + 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] + #[cfg_attr(not(test), rustc_diagnostic_item = "stringify_macro")] + macro_rules! stringify { + ($($t:tt)*) => { + /* compiler built-in */ + }; + } + + /// Includes a UTF-8 encoded file as a string. + /// + /// The file is located relative to the current file (similarly to how + /// modules are found). The provided path is interpreted in a platform-specific + /// way at compile time. So, for instance, an invocation with a Windows path + /// containing backslashes `\` would not compile correctly on Unix. + /// + /// This macro will yield an expression of type `&'static str` which is the + /// contents of the file. + /// + /// # Examples + /// + /// Assume there are two files in the same directory with the following + /// contents: + /// + /// File 'spanish.in': + /// + /// ```text + /// adiós + /// ``` + /// + /// File 'main.rs': + /// + /// ```ignore (cannot-doctest-external-file-dependency) + /// fn main() { + /// let my_str = include_str!("spanish.in"); + /// assert_eq!(my_str, "adiós\n"); + /// print!("{my_str}"); + /// } + /// ``` + /// + /// Compiling 'main.rs' and running the resulting binary will print "adiós". + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "include_str_macro")] + macro_rules! include_str { + ($file:expr $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Includes a file as a reference to a byte array. + /// + /// The file is located relative to the current file (similarly to how + /// modules are found). The provided path is interpreted in a platform-specific + /// way at compile time. So, for instance, an invocation with a Windows path + /// containing backslashes `\` would not compile correctly on Unix. + /// + /// This macro will yield an expression of type `&'static [u8; N]` which is + /// the contents of the file. + /// + /// # Examples + /// + /// Assume there are two files in the same directory with the following + /// contents: + /// + /// File 'spanish.in': + /// + /// ```text + /// adiós + /// ``` + /// + /// File 'main.rs': + /// + /// ```ignore (cannot-doctest-external-file-dependency) + /// fn main() { + /// let bytes = include_bytes!("spanish.in"); + /// assert_eq!(bytes, b"adi\xc3\xb3s\n"); + /// print!("{}", String::from_utf8_lossy(bytes)); + /// } + /// ``` + /// + /// Compiling 'main.rs' and running the resulting binary will print "adiós". + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "include_bytes_macro")] + macro_rules! include_bytes { + ($file:expr $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Expands to a string that represents the current module path. + /// + /// The current module path can be thought of as the hierarchy of modules + /// leading back up to the crate root. The first component of the path + /// returned is the name of the crate currently being compiled. + /// + /// # Examples + /// + /// ``` + /// mod test { + /// pub fn foo() { + /// assert!(module_path!().ends_with("test")); + /// } + /// } + /// + /// test::foo(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "module_path_macro")] + macro_rules! module_path { + () => { + /* compiler built-in */ + }; + } + + /// Evaluates boolean combinations of configuration flags at compile-time. + /// + /// In addition to the `#[cfg]` attribute, this macro is provided to allow + /// boolean expression evaluation of configuration flags. This frequently + /// leads to less duplicated code. + /// + /// The syntax given to this macro is the same syntax as the [`cfg`] + /// attribute. + /// + /// `cfg!`, unlike `#[cfg]`, does not remove any code and only evaluates to true or false. For + /// example, all blocks in an if/else expression need to be valid when `cfg!` is used for + /// the condition, regardless of what `cfg!` is evaluating. + /// + /// [`cfg`]: ../reference/conditional-compilation.html#the-cfg-attribute + /// + /// # Examples + /// + /// ``` + /// let my_directory = if cfg!(windows) { + /// "windows-specific-directory" + /// } else { + /// "unix-directory" + /// }; + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "cfg_macro")] + macro_rules! cfg { + ($($cfg:tt)*) => { + /* compiler built-in */ + }; + } + + /// Parses a file as an expression or an item according to the context. + /// + /// The file is located relative to the current file (similarly to how + /// modules are found). The provided path is interpreted in a platform-specific + /// way at compile time. So, for instance, an invocation with a Windows path + /// containing backslashes `\` would not compile correctly on Unix. + /// + /// Using this macro is often a bad idea, because if the file is + /// parsed as an expression, it is going to be placed in the + /// surrounding code unhygienically. This could result in variables + /// or functions being different from what the file expected if + /// there are variables or functions that have the same name in + /// the current file. + /// + /// # Examples + /// + /// Assume there are two files in the same directory with the following + /// contents: + /// + /// File 'monkeys.in': + /// + /// ```ignore (only-for-syntax-highlight) + /// ['🙈', '🙊', '🙉'] + /// .iter() + /// .cycle() + /// .take(6) + /// .collect::<String>() + /// ``` + /// + /// File 'main.rs': + /// + /// ```ignore (cannot-doctest-external-file-dependency) + /// fn main() { + /// let my_string = include!("monkeys.in"); + /// assert_eq!("🙈🙊🙉🙈🙊🙉", my_string); + /// println!("{my_string}"); + /// } + /// ``` + /// + /// Compiling 'main.rs' and running the resulting binary will print + /// "🙈🙊🙉🙈🙊🙉". + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[cfg_attr(not(test), rustc_diagnostic_item = "include_macro")] + macro_rules! include { + ($file:expr $(,)?) => {{ /* compiler built-in */ }}; + } + + /// Asserts that a boolean expression is `true` at runtime. + /// + /// This will invoke the [`panic!`] macro if the provided expression cannot be + /// evaluated to `true` at runtime. + /// + /// # Uses + /// + /// Assertions are always checked in both debug and release builds, and cannot + /// be disabled. See [`debug_assert!`] for assertions that are not enabled in + /// release builds by default. + /// + /// Unsafe code may rely on `assert!` to enforce run-time invariants that, if + /// violated could lead to unsafety. + /// + /// Other use-cases of `assert!` include testing and enforcing run-time + /// invariants in safe code (whose violation cannot result in unsafety). + /// + /// # Custom Messages + /// + /// This macro has a second form, where a custom panic message can + /// be provided with or without arguments for formatting. See [`std::fmt`] + /// for syntax for this form. Expressions used as format arguments will only + /// be evaluated if the assertion fails. + /// + /// [`std::fmt`]: ../std/fmt/index.html + /// + /// # Examples + /// + /// ``` + /// // the panic message for these assertions is the stringified value of the + /// // expression given. + /// assert!(true); + /// + /// fn some_computation() -> bool { true } // a very simple function + /// + /// assert!(some_computation()); + /// + /// // assert with a custom message + /// let x = true; + /// assert!(x, "x wasn't true!"); + /// + /// let a = 3; let b = 27; + /// assert!(a + b == 30, "a = {}, b = {}", a, b); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + #[macro_export] + #[rustc_diagnostic_item = "assert_macro"] + #[allow_internal_unstable(core_panic, edition_panic)] + macro_rules! assert { + ($cond:expr $(,)?) => {{ /* compiler built-in */ }}; + ($cond:expr, $($arg:tt)+) => {{ /* 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 used to apply derive macros. + /// + /// See [the reference] for more info. + /// + /// [the reference]: ../../../reference/attributes/derive.html + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_builtin_macro] + pub macro derive($item:item) { + /* compiler built-in */ + } + + /// Attribute macro applied to a function to turn it into a unit test. + /// + /// See [the reference] for more info. + /// + /// [the reference]: ../../../reference/attributes/testing.html#the-test-attribute + #[stable(feature = "rust1", since = "1.0.0")] + #[allow_internal_unstable(test, rustc_attrs)] + #[rustc_builtin_macro] + pub macro test($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. + /// + /// See also [`std::alloc::GlobalAlloc`](../../../std/alloc/trait.GlobalAlloc.html). + #[stable(feature = "global_allocator", since = "1.28.0")] + #[allow_internal_unstable(rustc_attrs)] + #[rustc_builtin_macro] + pub macro global_allocator($item:item) { + /* compiler built-in */ + } + + /// Keeps the item it's applied to if the passed path is accessible, and removes it otherwise. + #[unstable( + feature = "cfg_accessible", + issue = "64797", + reason = "`cfg_accessible` is not fully implemented" + )] + #[rustc_builtin_macro] + pub macro cfg_accessible($item:item) { + /* compiler built-in */ + } + + /// Expands all `#[cfg]` and `#[cfg_attr]` attributes in the code fragment it's applied to. + #[unstable( + feature = "cfg_eval", + issue = "82679", + reason = "`cfg_eval` is a recently implemented feature" + )] + #[rustc_builtin_macro] + pub macro cfg_eval($($tt:tt)*) { + /* 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, rt)] + #[deprecated(since = "1.52.0", note = "rustc-serialize is deprecated and no longer supported")] + #[doc(hidden)] // While technically stable, using it is unstable, and deprecated. Hide it. + pub macro RustcDecodable($item:item) { + /* compiler built-in */ + } + + /// Unstable implementation detail of the `rustc` compiler, do not use. + #[rustc_builtin_macro] + #[stable(feature = "rust1", since = "1.0.0")] + #[allow_internal_unstable(core_intrinsics, rt)] + #[deprecated(since = "1.52.0", note = "rustc-serialize is deprecated and no longer supported")] + #[doc(hidden)] // While technically stable, using it is unstable, and deprecated. Hide it. + pub macro RustcEncodable($item:item) { + /* compiler built-in */ + } +} |