diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index 21cd4f1500926..03af574094855 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -2091,10 +2091,10 @@ impl From<*mut T> for AtomicPtr { } #[allow(unused_macros)] // This macro ends up being unused on some architectures. -macro_rules! if_not_8_bit { - (u8, $($tt:tt)*) => { "" }; - (i8, $($tt:tt)*) => { "" }; - ($_:ident, $($tt:tt)*) => { $($tt)* }; +macro_rules! if_8_bit { + (u8, $( yes = [$($yes:tt)*], )? $( no = [$($no:tt)*], )? ) => { concat!("", $($($yes)*)?) }; + (i8, $( yes = [$($yes:tt)*], )? $( no = [$($no:tt)*], )? ) => { concat!("", $($($yes)*)?) }; + ($_:ident, $( yes = [$($yes:tt)*], )? $( no = [$($no:tt)*], )? ) => { concat!("", $($($no)*)?) }; } #[cfg(target_has_atomic_load_store)] @@ -2116,18 +2116,24 @@ macro_rules! atomic_int { $int_type:ident $atomic_type:ident) => { /// An integer type which can be safely shared between threads. /// - /// This type has the same size and bit validity as the underlying - /// integer type, [` + /// This type has the same + #[doc = if_8_bit!( + $int_type, + yes = ["size, alignment, and bit validity"], + no = ["size and bit validity"], + )] + /// as the underlying integer type, [` #[doc = $s_int_type] /// `]. - #[doc = if_not_8_bit! { + #[doc = if_8_bit! { $int_type, - concat!( + no = [ "However, the alignment of this type is always equal to its ", "size, even on targets where [`", $s_int_type, "`] has a ", "lesser alignment." - ) + ], }] + /// /// For more about the differences between atomic types and /// non-atomic types as well as information about the portability of /// this type, please see the [module-level documentation]. @@ -2220,9 +2226,19 @@ macro_rules! atomic_int { /// /// # Safety /// - #[doc = concat!(" * `ptr` must be aligned to \ - `align_of::<", stringify!($atomic_type), ">()` (note that on some platforms this \ - can be bigger than `align_of::<", stringify!($int_type), ">()`).")] + /// * `ptr` must be aligned to + #[doc = concat!(" `align_of::<", stringify!($atomic_type), ">()`")] + #[doc = if_8_bit!{ + $int_type, + yes = [ + " (note that this is always true, since `align_of::<", + stringify!($atomic_type), ">() == 1`)." + ], + no = [ + " (note that on some platforms this can be bigger than `align_of::<", + stringify!($int_type), ">()`)." + ], + }] /// * `ptr` must be [valid] for both reads and writes for the whole lifetime `'a`. /// * You must adhere to the [Memory model for atomic accesses]. In particular, it is not /// allowed to mix atomic and non-atomic accesses, or atomic accesses of different sizes, @@ -2261,12 +2277,12 @@ macro_rules! atomic_int { #[doc = concat!("Get atomic access to a `&mut ", stringify!($int_type), "`.")] /// - #[doc = if_not_8_bit! { + #[doc = if_8_bit! { $int_type, - concat!( + no = [ "**Note:** This function is only available on targets where `", stringify!($int_type), "` has an alignment of ", $align, " bytes." - ) + ], }] /// /// # Examples