From a4b7ed7a42c716ab9f05e351f003d589124fd55d Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:18:58 +0200 Subject: Adding upstream version 1.68.2+dfsg1. Signed-off-by: Daniel Baumann --- library/core/src/any.rs | 5 +- library/core/src/array/iter.rs | 6 +- library/core/src/array/mod.rs | 4 +- library/core/src/borrow.rs | 2 +- library/core/src/cell.rs | 35 +- library/core/src/cell/lazy.rs | 8 +- library/core/src/cell/once.rs | 13 +- library/core/src/char/decode.rs | 2 +- library/core/src/cmp.rs | 82 ++-- library/core/src/const_closure.rs | 29 -- library/core/src/convert/num.rs | 20 + library/core/src/ffi/mod.rs | 55 ++- library/core/src/fmt/mod.rs | 13 +- library/core/src/future/future.rs | 1 + library/core/src/future/mod.rs | 9 +- library/core/src/hash/mod.rs | 4 +- library/core/src/hint.rs | 69 +++ library/core/src/intrinsics.rs | 69 +-- library/core/src/intrinsics/mir.rs | 302 ++++++++++++- library/core/src/iter/range.rs | 2 +- library/core/src/iter/sources/empty.rs | 7 +- library/core/src/iter/sources/from_generator.rs | 23 +- library/core/src/iter/sources/once_with.rs | 14 +- library/core/src/iter/sources/repeat_n.rs | 2 +- library/core/src/iter/sources/repeat_with.rs | 10 +- library/core/src/iter/traits/accum.rs | 8 + library/core/src/iter/traits/iterator.rs | 43 +- library/core/src/lib.rs | 30 +- library/core/src/macros/mod.rs | 46 +- library/core/src/marker.rs | 20 +- library/core/src/mem/mod.rs | 3 +- library/core/src/num/dec2flt/fpu.rs | 2 +- library/core/src/num/f32.rs | 2 +- library/core/src/num/f64.rs | 2 +- library/core/src/num/int_macros.rs | 111 +++-- library/core/src/ops/function.rs | 319 -------------- library/core/src/ops/index.rs | 2 +- library/core/src/ops/mod.rs | 10 +- library/core/src/ops/unsize.rs | 20 +- library/core/src/option.rs | 57 ++- library/core/src/panic.rs | 8 +- library/core/src/panic/panic_info.rs | 2 +- library/core/src/panicking.rs | 39 +- library/core/src/pin.rs | 50 ++- library/core/src/prelude/mod.rs | 8 +- library/core/src/prelude/v1.rs | 9 +- library/core/src/ptr/alignment.rs | 12 +- library/core/src/ptr/const_ptr.rs | 110 ++--- library/core/src/ptr/metadata.rs | 2 +- library/core/src/ptr/mod.rs | 54 ++- library/core/src/ptr/mut_ptr.rs | 110 ++--- library/core/src/ptr/non_null.rs | 17 +- library/core/src/result.rs | 7 +- library/core/src/slice/iter.rs | 12 +- library/core/src/slice/iter/macros.rs | 22 +- library/core/src/slice/mod.rs | 61 ++- library/core/src/slice/sort.rs | 544 +++++++++++++++++++++++- library/core/src/str/iter.rs | 185 ++++---- library/core/src/str/mod.rs | 8 +- library/core/src/sync/atomic.rs | 40 +- library/core/src/sync/exclusive.rs | 4 +- library/core/src/task/poll.rs | 2 +- library/core/src/task/wake.rs | 10 +- library/core/src/unicode/mod.rs | 2 +- 64 files changed, 1782 insertions(+), 997 deletions(-) (limited to 'library/core/src') diff --git a/library/core/src/any.rs b/library/core/src/any.rs index 1a379ecc1..c0fb0d993 100644 --- a/library/core/src/any.rs +++ b/library/core/src/any.rs @@ -148,7 +148,7 @@ //! ``` //! //! In this example, if the concrete type of `obj` in `use_my_trait` is `SomeConcreteType`, then -//! the `get_context_ref` call will return a reference to `obj.some_string` with type `&String`. +//! the `get_context_by_ref` call will return a reference to `obj.some_string` with type `&String`. #![stable(feature = "rust1", since = "1.0.0")] @@ -662,7 +662,8 @@ impl dyn Any + Send + Sync { /// While `TypeId` implements `Hash`, `PartialOrd`, and `Ord`, it is worth /// noting that the hashes and ordering will vary between Rust releases. Beware /// of relying on them inside of your code! -#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)] +#[derive(Clone, Copy, Debug, Hash, Eq)] +#[derive_const(PartialEq, PartialOrd, Ord)] #[stable(feature = "rust1", since = "1.0.0")] pub struct TypeId { t: u64, diff --git a/library/core/src/array/iter.rs b/library/core/src/array/iter.rs index b91c63018..8259c087d 100644 --- a/library/core/src/array/iter.rs +++ b/library/core/src/array/iter.rs @@ -109,8 +109,8 @@ impl IntoIter { /// use std::array::IntoIter; /// use std::mem::MaybeUninit; /// - /// # // Hi! Thanks for reading the code. This is restricted to `Copy` because - /// # // otherwise it could leak. A fully-general version this would need a drop + /// # // Hi! Thanks for reading the code. This is restricted to `Copy` because + /// # // otherwise it could leak. A fully-general version this would need a drop /// # // guard to handle panics from the iterator, but this works for an example. /// fn next_chunk( /// it: &mut impl Iterator, @@ -211,7 +211,7 @@ impl IntoIter { let initialized = 0..0; // SAFETY: We're telling it that none of the elements are initialized, - // which is trivially true. And ∀N: usize, 0 <= N. + // which is trivially true. And ∀N: usize, 0 <= N. unsafe { Self::new_unchecked(buffer, initialized) } } diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs index 94a1a1d32..2825e0bbb 100644 --- a/library/core/src/array/mod.rs +++ b/library/core/src/array/mod.rs @@ -69,7 +69,7 @@ where /// if any element creation was unsuccessful. /// /// The return type of this function depends on the return type of the closure. -/// If you return `Result` from the closure, you'll get a `Result<[T; N]; E>`. +/// If you return `Result` from the closure, you'll get a `Result<[T; N], E>`. /// If you return `Option` from the closure, you'll get an `Option<[T; N]>`. /// /// # Arguments @@ -522,7 +522,7 @@ impl [T; N] { /// return an array the same size as `self` or the first error encountered. /// /// The return type of this function depends on the return type of the closure. - /// If you return `Result` from the closure, you'll get a `Result<[T; N]; E>`. + /// If you return `Result` from the closure, you'll get a `Result<[T; N], E>`. /// If you return `Option` from the closure, you'll get an `Option<[T; N]>`. /// /// # Examples diff --git a/library/core/src/borrow.rs b/library/core/src/borrow.rs index fdd56cb4e..4a8302ee4 100644 --- a/library/core/src/borrow.rs +++ b/library/core/src/borrow.rs @@ -26,7 +26,7 @@ /// to be modified, it can additionally implement [`BorrowMut`]. /// /// Further, when providing implementations for additional traits, it needs -/// to be considered whether they should behave identical to those of the +/// to be considered whether they should behave identically to those of the /// underlying type as a consequence of acting as a representation of that /// underlying type. Generic code typically uses `Borrow` when it relies /// on the identical behavior of these additional trait implementations. diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs index 47cce2aa3..129213fde 100644 --- a/library/core/src/cell.rs +++ b/library/core/src/cell.rs @@ -568,7 +568,7 @@ impl Cell { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U> CoerceUnsized> for Cell {} impl Cell<[T]> { @@ -807,7 +807,8 @@ impl RefCell { /// /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently borrowed, or + /// if `self` and `other` point to the same `RefCell`. /// /// # Examples /// @@ -1193,7 +1194,7 @@ impl Default for RefCell { impl PartialEq for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn eq(&self, other: &RefCell) -> bool { *self.borrow() == *other.borrow() @@ -1207,7 +1208,7 @@ impl Eq for RefCell {} impl PartialOrd for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn partial_cmp(&self, other: &RefCell) -> Option { self.borrow().partial_cmp(&*other.borrow()) @@ -1215,7 +1216,7 @@ impl PartialOrd for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn lt(&self, other: &RefCell) -> bool { *self.borrow() < *other.borrow() @@ -1223,7 +1224,7 @@ impl PartialOrd for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn le(&self, other: &RefCell) -> bool { *self.borrow() <= *other.borrow() @@ -1231,7 +1232,7 @@ impl PartialOrd for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn gt(&self, other: &RefCell) -> bool { *self.borrow() > *other.borrow() @@ -1239,7 +1240,7 @@ impl PartialOrd for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn ge(&self, other: &RefCell) -> bool { *self.borrow() >= *other.borrow() @@ -1250,7 +1251,7 @@ impl PartialOrd for RefCell { impl Ord for RefCell { /// # Panics /// - /// Panics if the value in either `RefCell` is currently borrowed. + /// Panics if the value in either `RefCell` is currently mutably borrowed. #[inline] fn cmp(&self, other: &RefCell) -> Ordering { self.borrow().cmp(&*other.borrow()) @@ -1266,7 +1267,7 @@ impl const From for RefCell { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U> CoerceUnsized> for RefCell {} struct BorrowRef<'b> { @@ -1492,7 +1493,7 @@ impl<'b, T: ?Sized> Ref<'b, T> { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'b, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized> for Ref<'b, T> {} #[stable(feature = "std_guard_impls", since = "1.20.0")] @@ -1738,7 +1739,7 @@ impl DerefMut for RefMut<'_, T> { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'b, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized> for RefMut<'b, T> {} #[stable(feature = "std_guard_impls", since = "1.20.0")] @@ -1783,7 +1784,7 @@ impl fmt::Display for RefMut<'_, T> { /// until the reference expires. As a special exception, given an `&T`, any part of it that is /// inside an `UnsafeCell<_>` may be deallocated during the lifetime of the reference, after the /// last time the reference is used (dereferenced or reborrowed). Since you cannot deallocate a part -/// of what a reference points to, this means the memory an `&T` points to can be deallocted only if +/// of what a reference points to, this means the memory an `&T` points to can be deallocated only if /// *every part of it* (including padding) is inside an `UnsafeCell`. /// /// However, whenever a `&UnsafeCell` is constructed or dereferenced, it must still point to @@ -1993,7 +1994,7 @@ impl UnsafeCell { #[rustc_const_stable(feature = "const_unsafecell_get", since = "1.32.0")] pub const fn get(&self) -> *mut T { // We can just cast the pointer from `UnsafeCell` to `T` because of - // #[repr(transparent)]. This exploits libstd's special status, there is + // #[repr(transparent)]. This exploits std's special status, there is // no guarantee for user code that this will work in future versions of the compiler! self as *const UnsafeCell as *const T as *mut T } @@ -2051,7 +2052,7 @@ impl UnsafeCell { #[rustc_const_stable(feature = "unsafe_cell_raw_get", since = "1.56.0")] pub const fn raw_get(this: *const Self) -> *mut T { // We can just cast the pointer from `UnsafeCell` to `T` because of - // #[repr(transparent)]. This exploits libstd's special status, there is + // #[repr(transparent)]. This exploits std's special status, there is // no guarantee for user code that this will work in future versions of the compiler! this as *const T as *mut T } @@ -2074,7 +2075,7 @@ impl const From for UnsafeCell { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U> CoerceUnsized> for UnsafeCell {} /// [`UnsafeCell`], but [`Sync`]. @@ -2164,7 +2165,7 @@ impl const From for SyncUnsafeCell { } } -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] //#[unstable(feature = "sync_unsafe_cell", issue = "95439")] impl, U> CoerceUnsized> for SyncUnsafeCell {} diff --git a/library/core/src/cell/lazy.rs b/library/core/src/cell/lazy.rs index b355d94ce..65d12c25c 100644 --- a/library/core/src/cell/lazy.rs +++ b/library/core/src/cell/lazy.rs @@ -35,7 +35,7 @@ pub struct LazyCell T> { init: Cell>, } -impl LazyCell { +impl T> LazyCell { /// Creates a new lazy value with the given initializing function. /// /// # Examples @@ -51,13 +51,12 @@ impl LazyCell { /// /// assert_eq!(&*lazy, "HELLO, WORLD!"); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub const fn new(init: F) -> LazyCell { LazyCell { cell: OnceCell::new(), init: Cell::new(Some(init)) } } -} -impl T> LazyCell { /// Forces the evaluation of this lazy value and returns a reference to /// the result. /// @@ -75,6 +74,7 @@ impl T> LazyCell { /// assert_eq!(LazyCell::force(&lazy), &92); /// assert_eq!(&*lazy, &92); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn force(this: &LazyCell) -> &T { this.cell.get_or_init(|| match this.init.take() { @@ -87,6 +87,7 @@ impl T> LazyCell { #[unstable(feature = "once_cell", issue = "74465")] impl T> Deref for LazyCell { type Target = T; + #[inline] fn deref(&self) -> &T { LazyCell::force(self) } @@ -95,6 +96,7 @@ impl T> Deref for LazyCell { #[unstable(feature = "once_cell", issue = "74465")] impl Default for LazyCell { /// Creates a new lazy value using `Default` as the initializing function. + #[inline] fn default() -> LazyCell { LazyCell::new(T::default) } diff --git a/library/core/src/cell/once.rs b/library/core/src/cell/once.rs index 8c01643c7..7757068a4 100644 --- a/library/core/src/cell/once.rs +++ b/library/core/src/cell/once.rs @@ -37,8 +37,9 @@ pub struct OnceCell { impl OnceCell { /// Creates a new empty cell. - #[unstable(feature = "once_cell", issue = "74465")] + #[inline] #[must_use] + #[unstable(feature = "once_cell", issue = "74465")] pub const fn new() -> OnceCell { OnceCell { inner: UnsafeCell::new(None) } } @@ -46,6 +47,7 @@ impl OnceCell { /// Gets the reference to the underlying value. /// /// Returns `None` if the cell is empty. + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn get(&self) -> Option<&T> { // SAFETY: Safe due to `inner`'s invariant @@ -55,6 +57,7 @@ impl OnceCell { /// Gets the mutable reference to the underlying value. /// /// Returns `None` if the cell is empty. + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn get_mut(&mut self) -> Option<&mut T> { self.inner.get_mut().as_mut() @@ -82,6 +85,7 @@ impl OnceCell { /// /// assert!(cell.get().is_some()); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn set(&self, value: T) -> Result<(), T> { // SAFETY: Safe because we cannot have overlapping mutable borrows @@ -123,6 +127,7 @@ impl OnceCell { /// let value = cell.get_or_init(|| unreachable!()); /// assert_eq!(value, &92); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn get_or_init(&self, f: F) -> &T where @@ -205,6 +210,7 @@ impl OnceCell { /// cell.set("hello".to_string()).unwrap(); /// assert_eq!(cell.into_inner(), Some("hello".to_string())); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn into_inner(self) -> Option { // Because `into_inner` takes `self` by value, the compiler statically verifies @@ -233,6 +239,7 @@ impl OnceCell { /// assert_eq!(cell.take(), Some("hello".to_string())); /// assert_eq!(cell.get(), None); /// ``` + #[inline] #[unstable(feature = "once_cell", issue = "74465")] pub fn take(&mut self) -> Option { mem::take(self).into_inner() @@ -241,6 +248,7 @@ impl OnceCell { #[unstable(feature = "once_cell", issue = "74465")] impl Default for OnceCell { + #[inline] fn default() -> Self { Self::new() } @@ -258,6 +266,7 @@ impl fmt::Debug for OnceCell { #[unstable(feature = "once_cell", issue = "74465")] impl Clone for OnceCell { + #[inline] fn clone(&self) -> OnceCell { let res = OnceCell::new(); if let Some(value) = self.get() { @@ -272,6 +281,7 @@ impl Clone for OnceCell { #[unstable(feature = "once_cell", issue = "74465")] impl PartialEq for OnceCell { + #[inline] fn eq(&self, other: &Self) -> bool { self.get() == other.get() } @@ -283,6 +293,7 @@ impl Eq for OnceCell {} #[unstable(feature = "once_cell", issue = "74465")] impl const From for OnceCell { /// Creates a new `OnceCell` which already contains the given `value`. + #[inline] fn from(value: T) -> Self { OnceCell { inner: UnsafeCell::new(Some(value)) } } diff --git a/library/core/src/char/decode.rs b/library/core/src/char/decode.rs index 11f1c30f6..eeb088030 100644 --- a/library/core/src/char/decode.rs +++ b/library/core/src/char/decode.rs @@ -67,7 +67,7 @@ impl> Iterator for DecodeUtf16 { } // all ok, so lets decode it. - let c = (((u - 0xD800) as u32) << 10 | (u2 - 0xDC00) as u32) + 0x1_0000; + let c = (((u & 0x3ff) as u32) << 10 | (u2 & 0x3ff) as u32) + 0x1_0000; // SAFETY: we checked that it's a legal unicode value Some(Ok(unsafe { from_u32_unchecked(c) })) } diff --git a/library/core/src/cmp.rs b/library/core/src/cmp.rs index 949896e57..a7d6fec7d 100644 --- a/library/core/src/cmp.rs +++ b/library/core/src/cmp.rs @@ -24,8 +24,6 @@ use crate::const_closure::ConstFnMutClosure; use crate::marker::Destruct; -#[cfg(bootstrap)] -use crate::marker::StructuralPartialEq; use self::Ordering::*; @@ -333,7 +331,7 @@ pub struct AssertParamIsEq { /// assert_eq!(Ordering::Greater, result); /// ``` #[derive(Clone, Copy, Eq, Debug, Hash)] -#[cfg_attr(not(bootstrap), derive_const(PartialOrd, Ord, PartialEq))] +#[derive_const(PartialOrd, Ord, PartialEq)] #[stable(feature = "rust1", since = "1.0.0")] #[repr(i8)] pub enum Ordering { @@ -800,9 +798,12 @@ pub trait Ord: Eq + PartialOrd { Self: Sized, Self: ~const Destruct, { - // HACK(fee1-dead): go back to using `self.max_by(other, Ord::cmp)` - // when trait methods are allowed to be used when a const closure is - // expected. + #[cfg(not(bootstrap))] + { + max_by(self, other, Ord::cmp) + } + + #[cfg(bootstrap)] match self.cmp(&other) { Ordering::Less | Ordering::Equal => other, Ordering::Greater => self, @@ -827,9 +828,12 @@ pub trait Ord: Eq + PartialOrd { Self: Sized, Self: ~const Destruct, { - // HACK(fee1-dead): go back to using `self.min_by(other, Ord::cmp)` - // when trait methods are allowed to be used when a const closure is - // expected. + #[cfg(not(bootstrap))] + { + min_by(self, other, Ord::cmp) + } + + #[cfg(bootstrap)] match self.cmp(&other) { Ordering::Less | Ordering::Equal => self, Ordering::Greater => other, @@ -879,40 +883,6 @@ pub macro Ord($item:item) { /* compiler built-in */ } -#[stable(feature = "rust1", since = "1.0.0")] -#[cfg(bootstrap)] -impl StructuralPartialEq for Ordering {} - -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_const_unstable(feature = "const_cmp", issue = "92391")] -#[cfg(bootstrap)] -impl const PartialEq for Ordering { - #[inline] - fn eq(&self, other: &Self) -> bool { - (*self as i32).eq(&(*other as i32)) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_const_unstable(feature = "const_cmp", issue = "92391")] -#[cfg(bootstrap)] -impl const Ord for Ordering { - #[inline] - fn cmp(&self, other: &Ordering) -> Ordering { - (*self as i32).cmp(&(*other as i32)) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_const_unstable(feature = "const_cmp", issue = "92391")] -#[cfg(bootstrap)] -impl const PartialOrd for Ordering { - #[inline] - fn partial_cmp(&self, other: &Ordering) -> Option { - (*self as i32).partial_cmp(&(*other as i32)) - } -} - /// Trait for types that form a [partial order](https://en.wikipedia.org/wiki/Partial_order). /// /// The `lt`, `le`, `gt`, and `ge` methods of this trait can be called using @@ -1264,17 +1234,23 @@ where F: ~const Destruct, K: ~const Destruct, { - const fn imp K, K: ~const Ord>( - f: &mut F, - (v1, v2): (&T, &T), - ) -> Ordering - where - T: ~const Destruct, - K: ~const Destruct, - { - f(v1).cmp(&f(v2)) + cfg_if! { + if #[cfg(bootstrap)] { + const fn imp K, K: ~const Ord>( + f: &mut F, + (v1, v2): (&T, &T), + ) -> Ordering + where + T: ~const Destruct, + K: ~const Destruct, + { + f(v1).cmp(&f(v2)) + } + min_by(v1, v2, ConstFnMutClosure::new(&mut f, imp)) + } else { + min_by(v1, v2, const |v1, v2| f(v1).cmp(&f(v2))) + } } - min_by(v1, v2, ConstFnMutClosure::new(&mut f, imp)) } /// Compares and returns the maximum of two values. diff --git a/library/core/src/const_closure.rs b/library/core/src/const_closure.rs index 151c8e6d8..97900a486 100644 --- a/library/core/src/const_closure.rs +++ b/library/core/src/const_closure.rs @@ -1,5 +1,4 @@ use crate::marker::Destruct; -#[cfg(not(bootstrap))] use crate::marker::Tuple; /// Struct representing a closure with mutably borrowed data. @@ -46,33 +45,6 @@ impl<'a, CapturedData: ?Sized, Function> ConstFnMutClosure<&'a mut CapturedData, macro_rules! impl_fn_mut_tuple { ($($var:ident)*) => { - #[cfg(bootstrap)] - #[allow(unused_parens)] - impl<'a, $($var,)* ClosureArguments, Function, ClosureReturnValue> const - FnOnce for ConstFnMutClosure<($(&'a mut $var),*), Function> - where - Function: ~const Fn(($(&mut $var),*), ClosureArguments) -> ClosureReturnValue+ ~const Destruct, - { - type Output = ClosureReturnValue; - - extern "rust-call" fn call_once(mut self, args: ClosureArguments) -> Self::Output { - self.call_mut(args) - } - } - #[cfg(bootstrap)] - #[allow(unused_parens)] - impl<'a, $($var,)* ClosureArguments, Function, ClosureReturnValue> const - FnMut for ConstFnMutClosure<($(&'a mut $var),*), Function> - where - Function: ~const Fn(($(&mut $var),*), ClosureArguments)-> ClosureReturnValue, - { - extern "rust-call" fn call_mut(&mut self, args: ClosureArguments) -> Self::Output { - #[allow(non_snake_case)] - let ($($var),*) = &mut self.data; - (self.func)(($($var),*), args) - } - } - #[cfg(not(bootstrap))] #[allow(unused_parens)] impl<'a, $($var,)* ClosureArguments: Tuple, Function, ClosureReturnValue> const FnOnce for ConstFnMutClosure<($(&'a mut $var),*), Function> @@ -85,7 +57,6 @@ macro_rules! impl_fn_mut_tuple { self.call_mut(args) } } - #[cfg(not(bootstrap))] #[allow(unused_parens)] impl<'a, $($var,)* ClosureArguments: Tuple, Function, ClosureReturnValue> const FnMut for ConstFnMutClosure<($(&'a mut $var),*), Function> diff --git a/library/core/src/convert/num.rs b/library/core/src/convert/num.rs index 9c0d7e9a1..4da7c3234 100644 --- a/library/core/src/convert/num.rs +++ b/library/core/src/convert/num.rs @@ -168,6 +168,26 @@ impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0" // Float -> Float impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] } +// bool -> Float +#[stable(feature = "float_from_bool", since = "1.68.0")] +#[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")] +impl const From for f32 { + /// Converts `bool` to `f32` losslessly. + #[inline] + fn from(small: bool) -> Self { + small as u8 as Self + } +} +#[stable(feature = "float_from_bool", since = "1.68.0")] +#[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")] +impl const From for f64 { + /// Converts `bool` to `f64` losslessly. + #[inline] + fn from(small: bool) -> Self { + small as u8 as Self + } +} + // no possible bounds violation macro_rules! try_from_unbounded { ($source:ty, $($target:ty),*) => {$( diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs index ec1eaa99f..76daceecd 100644 --- a/library/core/src/ffi/mod.rs +++ b/library/core/src/ffi/mod.rs @@ -227,7 +227,12 @@ impl fmt::Debug for c_void { /// Basic implementation of a `va_list`. // The name is WIP, using `VaListImpl` for now. #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -251,7 +256,12 @@ pub struct VaListImpl<'f> { } #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -319,6 +329,25 @@ pub struct VaListImpl<'f> { _marker: PhantomData<&'f mut &'f c_void>, } +/// s390x ABI implementation of a `va_list`. +#[cfg(target_arch = "s390x")] +#[repr(C)] +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + gpr: i64, + fpr: i64, + overflow_arg_area: *mut c_void, + reg_save_area: *mut c_void, + _marker: PhantomData<&'f mut &'f c_void>, +} + /// x86_64 ABI implementation of a `va_list`. #[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(windows)))] #[repr(C)] @@ -352,6 +381,7 @@ pub struct VaList<'a, 'f: 'a> { all( not(target_arch = "aarch64"), not(target_arch = "powerpc"), + not(target_arch = "s390x"), not(target_arch = "x86_64") ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), @@ -363,7 +393,12 @@ pub struct VaList<'a, 'f: 'a> { inner: VaListImpl<'f>, #[cfg(all( - any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"), + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))), not(target_family = "wasm"), not(target_arch = "asmjs"), @@ -376,7 +411,12 @@ pub struct VaList<'a, 'f: 'a> { } #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -398,7 +438,12 @@ impl<'f> VaListImpl<'f> { } #[cfg(all( - any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"), + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))), not(target_family = "wasm"), not(target_arch = "asmjs"), diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs index 48b617743..fa5073e33 100644 --- a/library/core/src/fmt/mod.rs +++ b/library/core/src/fmt/mod.rs @@ -174,6 +174,11 @@ pub trait Write { /// This method should generally not be invoked manually, but rather through /// the [`write!`] macro itself. /// + /// # Errors + /// + /// This function will return an instance of [`Error`] on error. Please see + /// [write_str](Write::write_str) for details. + /// /// # Examples /// /// ``` @@ -405,7 +410,7 @@ impl<'a> Arguments<'a> { /// 1. The `pieces` slice must be at least as long as `fmt`. /// 2. Every [`rt::v1::Argument::position`] value within `fmt` must be a /// valid index of `args`. - /// 3. Every [`Count::Param`] within `fmt` must contain a valid index of + /// 3. Every [`rt::v1::Count::Param`] within `fmt` must contain a valid index of /// `args`. #[doc(hidden)] #[inline] @@ -558,7 +563,7 @@ impl Display for Arguments<'_> { /// /// Derived `Debug` formats are not stable, and so may change with future Rust /// versions. Additionally, `Debug` implementations of types provided by the -/// standard library (`libstd`, `libcore`, `liballoc`, etc.) are not stable, and +/// standard library (`std`, `core`, `alloc`, etc.) are not stable, and /// may also change with future Rust versions. /// /// # Examples @@ -2471,8 +2476,8 @@ impl Display for char { #[stable(feature = "rust1", since = "1.0.0")] impl Pointer for *const T { fn fmt(&self, f: &mut Formatter<'_>) -> Result { - // Cast is needed here because `.addr()` requires `T: Sized`. - pointer_fmt_inner((*self as *const ()).addr(), f) + // Cast is needed here because `.expose_addr()` requires `T: Sized`. + pointer_fmt_inner((*self as *const ()).expose_addr(), f) } } diff --git a/library/core/src/future/future.rs b/library/core/src/future/future.rs index f29d3e1e9..8c7111cb3 100644 --- a/library/core/src/future/future.rs +++ b/library/core/src/future/future.rs @@ -37,6 +37,7 @@ use crate::task::{Context, Poll}; pub trait Future { /// The type of value produced on completion. #[stable(feature = "futures_api", since = "1.36.0")] + #[rustc_diagnostic_item = "FutureOutput"] type Output; /// Attempt to resolve the future to a final value, registering diff --git a/library/core/src/future/mod.rs b/library/core/src/future/mod.rs index f2b961d62..c4fb36209 100644 --- a/library/core/src/future/mod.rs +++ b/library/core/src/future/mod.rs @@ -44,7 +44,7 @@ pub use poll_fn::{poll_fn, PollFn}; /// non-Send/Sync as well, and we don't want that. /// /// It also simplifies the HIR lowering of `.await`. -#[cfg_attr(not(bootstrap), lang = "ResumeTy")] +#[lang = "ResumeTy"] #[doc(hidden)] #[unstable(feature = "gen_future", issue = "50547")] #[derive(Debug, Copy, Clone)] @@ -61,7 +61,6 @@ unsafe impl Sync for ResumeTy {} /// This function returns a `GenFuture` underneath, but hides it in `impl Trait` to give /// better error messages (`impl Future` rather than `GenFuture<[closure.....]>`). // This is `const` to avoid extra errors after we recover from `const async fn` -#[cfg_attr(bootstrap, lang = "from_generator")] #[doc(hidden)] #[unstable(feature = "gen_future", issue = "50547")] #[rustc_const_unstable(feature = "gen_future", issue = "50547")] @@ -113,10 +112,14 @@ pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> { unsafe { &mut *cx.0.as_ptr().cast() } } -#[cfg_attr(not(bootstrap), lang = "identity_future")] +// FIXME(swatinem): This fn is currently needed to work around shortcomings +// in type and lifetime inference. +// See the comment at the bottom of `LoweringContext::make_async_expr` and +// . #[doc(hidden)] #[unstable(feature = "gen_future", issue = "50547")] #[inline] +#[lang = "identity_future"] pub const fn identity_future>(f: Fut) -> Fut { f } diff --git a/library/core/src/hash/mod.rs b/library/core/src/hash/mod.rs index c755afa39..71a0d1825 100644 --- a/library/core/src/hash/mod.rs +++ b/library/core/src/hash/mod.rs @@ -199,7 +199,7 @@ pub trait Hash { /// println!("Hash is {:x}!", hasher.finish()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] - fn hash(&self, state: &mut H); + fn hash(&self, state: &mut H); /// Feeds a slice of this type into the given [`Hasher`]. /// @@ -980,7 +980,7 @@ mod impls { #[rustc_const_unstable(feature = "const_hash", issue = "104061")] impl const Hash for &mut T { #[inline] - fn hash(&self, state: &mut H) { + fn hash(&self, state: &mut H) { (**self).hash(state); } } diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs index e8d724ab1..5a76e8669 100644 --- a/library/core/src/hint.rs +++ b/library/core/src/hint.rs @@ -219,6 +219,75 @@ pub fn spin_loop() { /// backend used. Programs cannot rely on `black_box` for *correctness* in any way. /// /// [`std::convert::identity`]: crate::convert::identity +/// +/// # When is this useful? +/// +/// First and foremost: `black_box` does _not_ guarantee any exact behavior and, in some cases, may +/// do nothing at all. As such, it **must not be relied upon to control critical program behavior.** +/// This _immediately_ precludes any direct use of this function for cryptographic or security +/// purposes. +/// +/// While not suitable in those mission-critical cases, `back_box`'s functionality can generally be +/// relied upon for benchmarking, and should be used there. It will try to ensure that the +/// compiler doesn't optimize away part of the intended test code based on context. For +/// example: +/// +/// ``` +/// fn contains(haystack: &[&str], needle: &str) -> bool { +/// haystack.iter().any(|x| x == &needle) +/// } +/// +/// pub fn benchmark() { +/// let haystack = vec!["abc", "def", "ghi", "jkl", "mno"]; +/// let needle = "ghi"; +/// for _ in 0..10 { +/// contains(&haystack, needle); +/// } +/// } +/// ``` +/// +/// The compiler could theoretically make optimizations like the following: +/// +/// - `needle` and `haystack` are always the same, move the call to `contains` outside the loop and +/// delete the loop +/// - Inline `contains` +/// - `needle` and `haystack` have values known at compile time, `contains` is always true. Remove +/// the call and replace with `true` +/// - Nothing is done with the result of `contains`: delete this function call entirely +/// - `benchmark` now has no purpose: delete this function +/// +/// It is not likely that all of the above happens, but the compiler is definitely able to make some +/// optimizations that could result in a very inaccurate benchmark. This is where `black_box` comes +/// in: +/// +/// ``` +/// use std::hint::black_box; +/// +/// // Same `contains` function +/// fn contains(haystack: &[&str], needle: &str) -> bool { +/// haystack.iter().any(|x| x == &needle) +/// } +/// +/// pub fn benchmark() { +/// let haystack = vec!["abc", "def", "ghi", "jkl", "mno"]; +/// let needle = "ghi"; +/// for _ in 0..10 { +/// // Adjust our benchmark loop contents +/// black_box(contains(black_box(&haystack), black_box(needle))); +/// } +/// } +/// ``` +/// +/// This essentially tells the compiler to block optimizations across any calls to `black_box`. So, +/// it now: +/// +/// - Treats both arguments to `contains` as unpredictable: the body of `contains` can no longer be +/// optimized based on argument values +/// - Treats the call to `contains` and its result as volatile: the body of `benchmark` cannot +/// optimize this away +/// +/// This makes our benchmark much more realistic to how the function would be used in situ, where +/// arguments are usually not known at compile time and the result is used in some way. #[inline] #[stable(feature = "bench_black_box", since = "1.66.0")] #[rustc_const_unstable(feature = "const_black_box", issue = "none")] diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs index 7ed7d767f..a315a28fb 100644 --- a/library/core/src/intrinsics.rs +++ b/library/core/src/intrinsics.rs @@ -55,7 +55,6 @@ #![allow(missing_docs)] use crate::marker::DiscriminantKind; -#[cfg(not(bootstrap))] use crate::marker::Tuple; use crate::mem; @@ -959,13 +958,13 @@ extern "rust-intrinsic" { #[rustc_safe_intrinsic] pub fn assert_zero_valid(); - /// A guard for unsafe functions that cannot ever be executed if `T` has invalid - /// bit patterns: This will statically either panic, or do nothing. + /// A guard for `std::mem::uninitialized`. This will statically either panic, or do nothing. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_assert_type2", issue = "none")] #[rustc_safe_intrinsic] - pub fn assert_uninit_valid(); + #[cfg(not(bootstrap))] + pub fn assert_mem_uninitialized_valid(); /// Gets a reference to a static `Location` indicating where it was called. /// @@ -2175,66 +2174,6 @@ extern "rust-intrinsic" { /// `unreachable_unchecked` is actually being reached. The bug is in *crate A*, /// which violates the principle that a `const fn` must behave the same at /// compile-time and at run-time. The unsafe code in crate B is fine. - #[cfg(bootstrap)] - #[rustc_const_unstable(feature = "const_eval_select", issue = "none")] - pub fn const_eval_select(arg: ARG, called_in_const: F, called_at_rt: G) -> RET - where - G: FnOnce, - F: FnOnce; - - /// Selects which function to call depending on the context. - /// - /// If this function is evaluated at compile-time, then a call to this - /// intrinsic will be replaced with a call to `called_in_const`. It gets - /// replaced with a call to `called_at_rt` otherwise. - /// - /// # Type Requirements - /// - /// The two functions must be both function items. They cannot be function - /// pointers or closures. The first function must be a `const fn`. - /// - /// `arg` will be the tupled arguments that will be passed to either one of - /// the two functions, therefore, both functions must accept the same type of - /// arguments. Both functions must return RET. - /// - /// # Safety - /// - /// The two functions must behave observably equivalent. Safe code in other - /// crates may assume that calling a `const fn` at compile-time and at run-time - /// produces the same result. A function that produces a different result when - /// evaluated at run-time, or has any other observable side-effects, is - /// *unsound*. - /// - /// Here is an example of how this could cause a problem: - /// ```no_run - /// #![feature(const_eval_select)] - /// #![feature(core_intrinsics)] - /// use std::hint::unreachable_unchecked; - /// use std::intrinsics::const_eval_select; - /// - /// // Crate A - /// pub const fn inconsistent() -> i32 { - /// fn runtime() -> i32 { 1 } - /// const fn compiletime() -> i32 { 2 } - /// - /// unsafe { - // // ⚠ This code violates the required equivalence of `compiletime` - /// // and `runtime`. - /// const_eval_select((), compiletime, runtime) - /// } - /// } - /// - /// // Crate B - /// const X: i32 = inconsistent(); - /// let x = inconsistent(); - /// if x != X { unsafe { unreachable_unchecked(); }} - /// ``` - /// - /// This code causes Undefined Behavior when being run, since the - /// `unreachable_unchecked` is actually being reached. The bug is in *crate A*, - /// which violates the principle that a `const fn` must behave the same at - /// compile-time and at run-time. The unsafe code in crate B is fine. - #[cfg(not(bootstrap))] #[rustc_const_unstable(feature = "const_eval_select", issue = "none")] pub fn const_eval_select( arg: ARG, @@ -2281,7 +2220,7 @@ macro_rules! assert_unsafe_precondition { fn runtime$(<$($tt)*>)?($($i:$ty),*) { if !$e { // don't unwind to reduce impact on code size - ::core::panicking::panic_str_nounwind( + ::core::panicking::panic_nounwind( concat!("unsafe precondition(s) violated: ", $name) ); } diff --git a/library/core/src/intrinsics/mir.rs b/library/core/src/intrinsics/mir.rs index 8ba1c1228..e3157b669 100644 --- a/library/core/src/intrinsics/mir.rs +++ b/library/core/src/intrinsics/mir.rs @@ -21,15 +21,14 @@ //! #[custom_mir(dialect = "built")] //! pub fn simple(x: i32) -> i32 { //! mir!( -//! let temp1: i32; -//! let temp2: _; +//! let temp2: i32; //! //! { -//! temp1 = x; -//! Goto(exit) +//! let temp1 = x; +//! Goto(my_second_block) //! } //! -//! exit = { +//! my_second_block = { //! temp2 = Move(temp1); //! RET = temp2; //! Return() @@ -38,22 +37,200 @@ //! } //! ``` //! -//! Hopefully most of this is fairly self-explanatory. Expanding on some notable details: +//! The `custom_mir` attribute tells the compiler to treat the function as being custom MIR. This +//! attribute only works on functions - there is no way to insert custom MIR into the middle of +//! another function. The `dialect` and `phase` parameters indicate which [version of MIR][dialect +//! docs] you are inserting here. Generally you'll want to use `#![custom_mir(dialect = "built")]` +//! if you want your MIR to be modified by the full MIR pipeline, or `#![custom_mir(dialect = +//! "runtime", phase = "optimized")] if you don't. //! -//! - The `custom_mir` attribute tells the compiler to treat the function as being custom MIR. This -//! attribute only works on functions - there is no way to insert custom MIR into the middle of -//! another function. -//! - The `dialect` and `phase` parameters indicate which version of MIR you are inserting here. -//! This will normally be the phase that corresponds to the thing you are trying to test. The -//! phase can be omitted for dialects that have just one. -//! - You should define your function signature like you normally would. Externally, this function -//! can be called like any other function. -//! - Type inference works - you don't have to spell out the type of all of your locals. +//! [dialect docs]: +//! https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/enum.MirPhase.html //! -//! For now, all statements and terminators are parsed from nested invocations of the special -//! functions provided in this module. We additionally want to (but do not yet) support more -//! "normal" Rust syntax in places where it makes sense. Also, most kinds of instructions are not -//! supported yet. +//! The input to the [`mir!`] macro is: +//! +//! - A possibly empty list of local declarations. Locals can also be declared inline on +//! assignments via `let`. Type inference generally works. Shadowing does not. +//! - A list of basic blocks. The first of these is the start block and is where execution begins. +//! All blocks other than the start block need to be given a name, so that they can be referred +//! to later. +//! - Each block is a list of semicolon terminated statements, followed by a terminator. The +//! syntax for the various statements and terminators is designed to be as similar as possible +//! to the syntax for analogous concepts in native Rust. See below for a list. +//! +//! # Examples +//! +#![cfg_attr(bootstrap, doc = "```rust,compile_fail")] +#![cfg_attr(not(bootstrap), doc = "```rust")] +//! #![feature(core_intrinsics, custom_mir)] +//! +//! extern crate core; +//! use core::intrinsics::mir::*; +//! +//! #[custom_mir(dialect = "built")] +//! pub fn choose_load(a: &i32, b: &i32, c: bool) -> i32 { +//! mir!( +//! { +//! match c { +//! true => t, +//! _ => f, +//! } +//! } +//! +//! t = { +//! let temp = a; +//! Goto(load_and_exit) +//! } +//! +//! f = { +//! temp = b; +//! Goto(load_and_exit) +//! } +//! +//! load_and_exit = { +//! RET = *temp; +//! Return() +//! } +//! ) +//! } +//! +//! #[custom_mir(dialect = "built")] +//! fn unwrap_unchecked(opt: Option) -> T { +//! mir!({ +//! RET = Move(Field(Variant(opt, 1), 0)); +//! Return() +//! }) +//! } +//! +//! #[custom_mir(dialect = "runtime", phase = "optimized")] +//! fn push_and_pop(v: &mut Vec, value: T) { +//! mir!( +//! let unused; +//! let popped; +//! +//! { +//! Call(unused, pop, Vec::push(v, value)) +//! } +//! +//! pop = { +//! Call(popped, drop, Vec::pop(v)) +//! } +//! +//! drop = { +//! Drop(popped, ret) +//! } +//! +//! ret = { +//! Return() +//! } +//! ) +//! } +//! ``` +//! +//! We can also set off compilation failures that happen in sufficiently late stages of the +//! compiler: +//! +//! ```rust,compile_fail +//! #![feature(core_intrinsics, custom_mir)] +//! +//! extern crate core; +//! use core::intrinsics::mir::*; +//! +//! #[custom_mir(dialect = "built")] +//! fn borrow_error(should_init: bool) -> i32 { +//! mir!( +//! let temp: i32; +//! +//! { +//! match should_init { +//! true => init, +//! _ => use_temp, +//! } +//! } +//! +//! init = { +//! temp = 0; +//! Goto(use_temp) +//! } +//! +//! use_temp = { +//! RET = temp; +//! Return() +//! } +//! ) +//! } +//! ``` +//! +//! ```text +//! error[E0381]: used binding is possibly-uninitialized +//! --> test.rs:24:13 +//! | +//! 8 | / mir!( +//! 9 | | let temp: i32; +//! 10 | | +//! 11 | | { +//! ... | +//! 19 | | temp = 0; +//! | | -------- binding initialized here in some conditions +//! ... | +//! 24 | | RET = temp; +//! | | ^^^^^^^^^^ value used here but it is possibly-uninitialized +//! 25 | | Return() +//! 26 | | } +//! 27 | | ) +//! | |_____- binding declared here but left uninitialized +//! +//! error: aborting due to previous error +//! +//! For more information about this error, try `rustc --explain E0381`. +//! ``` +//! +//! # Syntax +//! +//! The lists below are an exhaustive description of how various MIR constructs can be created. +//! Anything missing from the list should be assumed to not be supported, PRs welcome. +//! +//! #### Locals +//! +//! - The `_0` return local can always be accessed via `RET`. +//! - Arguments can be accessed via their regular name. +//! - All other locals need to be declared with `let` somewhere and then can be accessed by name. +//! +//! #### Places +//! - Locals implicit convert to places. +//! - Field accesses, derefs, and indexing work normally. +//! - Fields in variants can be accessed via the [`Variant`] and [`Field`] associated functions, +//! see their documentation for details. +//! +//! #### Operands +//! - Places implicitly convert to `Copy` operands. +//! - `Move` operands can be created via [`Move`]. +//! - Const blocks, literals, named constants, and const params all just work. +//! - [`Static`] and [`StaticMut`] can be used to create `&T` and `*mut T`s to statics. These are +//! constants in MIR and the only way to access statics. +//! +//! #### Statements +//! - Assign statements work via normal Rust assignment. +//! - [`Retag`] statements have an associated function. +//! +//! #### Rvalues +//! +//! - Operands implicitly convert to `Use` rvalues. +//! - `&`, `&mut`, `addr_of!`, and `addr_of_mut!` all work to create their associated rvalue. +//! - [`Discriminant`] has an associated function. +//! +//! #### Terminators +//! +//! Custom MIR does not currently support cleanup blocks or non-trivial unwind paths. As such, there +//! are no resume and abort terminators, and terminators that might unwind do not have any way to +//! indicate the unwind block. +//! +//! - [`Goto`], [`Return`], [`Unreachable`], [`Drop`](Drop()), and [`DropAndReplace`] have associated functions. +//! - `match some_int_operand` becomes a `SwitchInt`. Each arm should be `literal => basic_block` +//! - The exception is the last arm, which must be `_ => basic_block` and corresponds to the +//! otherwise branch. +//! - [`Call`] has an associated function as well. The third argument of this function is a normal +//! function call expresion, for example `my_other_function(a, 5)`. //! #![unstable( @@ -69,21 +246,93 @@ pub struct BasicBlock; macro_rules! define { - ($name:literal, $($sig:tt)*) => { + ($name:literal, $( #[ $meta:meta ] )* fn $($sig:tt)*) => { #[rustc_diagnostic_item = $name] - pub $($sig)* { panic!() } + $( #[ $meta ] )* + pub fn $($sig)* { panic!() } } } define!("mir_return", fn Return() -> BasicBlock); define!("mir_goto", fn Goto(destination: BasicBlock) -> BasicBlock); +define!("mir_unreachable", fn Unreachable() -> BasicBlock); +define!("mir_drop", fn Drop(place: T, goto: BasicBlock)); +define!("mir_drop_and_replace", fn DropAndReplace(place: T, value: T, goto: BasicBlock)); +define!("mir_call", fn Call(place: T, goto: BasicBlock, call: T)); +define!("mir_storage_live", fn StorageLive(local: T)); +define!("mir_storage_dead", fn StorageDead(local: T)); define!("mir_retag", fn Retag(place: T)); -define!("mir_retag_raw", fn RetagRaw(place: T)); define!("mir_move", fn Move(place: T) -> T); define!("mir_static", fn Static(s: T) -> &'static T); define!("mir_static_mut", fn StaticMut(s: T) -> *mut T); +define!( + "mir_discriminant", + /// Gets the discriminant of a place. + fn Discriminant(place: T) -> ::Discriminant +); +define!("mir_set_discriminant", fn SetDiscriminant(place: T, index: u32)); +define!( + "mir_field", + /// Access the field with the given index of some place. + /// + /// This only makes sense to use in conjunction with [`Variant`]. If the type you are looking to + /// access the field of does not have variants, you can use normal field projection syntax. + /// + /// There is no proper way to do a place projection to a variant in Rust, and so these two + /// functions are a workaround. You can access a field of a variant via `Field(Variant(place, + /// var_idx), field_idx)`, where `var_idx` and `field_idx` are appropriate literals. Some + /// caveats: + /// + /// - The return type of `Variant` is always `()`. Don't worry about that, the correct MIR will + /// still be generated. + /// - In some situations, the return type of `Field` cannot be inferred. You may need to + /// annotate it on the function in these cases. + /// - Since `Field` is a function call which is not a place expression, using this on the left + /// hand side of an expression is rejected by the compiler. [`place!`] is a macro provided to + /// work around that issue. Wrap the left hand side of an assignment in the macro to convince + /// the compiler that it's ok. + /// + /// # Examples + /// + #[cfg_attr(bootstrap, doc = "```rust,compile_fail")] + #[cfg_attr(not(bootstrap), doc = "```rust")] + /// #![feature(custom_mir, core_intrinsics)] + /// + /// extern crate core; + /// use core::intrinsics::mir::*; + /// + /// #[custom_mir(dialect = "built")] + /// fn unwrap_deref(opt: Option<&i32>) -> i32 { + /// mir!({ + /// RET = *Field::<&i32>(Variant(opt, 1), 0); + /// Return() + /// }) + /// } + /// + /// #[custom_mir(dialect = "built")] + /// fn set(opt: &mut Option) { + /// mir!({ + /// place!(Field(Variant(*opt, 1), 0)) = 5; + /// Return() + /// }) + /// } + /// ``` + fn Field(place: (), field: u32) -> F +); +define!( + "mir_variant", + /// Adds a variant projection with the given index to the place. + /// + /// See [`Field`] for documentation. + fn Variant(place: T, index: u32) -> () +); +define!( + "mir_make_place", + #[doc(hidden)] + fn __internal_make_place(place: T) -> *mut T +); -/// Convenience macro for generating custom MIR. +/// Macro for generating custom MIR. /// /// See the module documentation for syntax details. This macro is not magic - it only transforms /// your MIR into something that is easier to parse in the compiler. @@ -139,6 +388,13 @@ pub macro mir { }} } +/// Helper macro that allows you to treat a value expression like a place expression. +/// +/// See the documentation on [`Variant`] for why this is necessary and how to use it. +pub macro place($e:expr) { + (*::core::intrinsics::mir::__internal_make_place($e)) +} + /// Helper macro that extracts the `let` declarations out of a bunch of statements. /// /// This macro is written using the "statement muncher" strategy. Each invocation parses the first diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs index ac7b389b1..b5739f2f3 100644 --- a/library/core/src/iter/range.rs +++ b/library/core/src/iter/range.rs @@ -756,7 +756,7 @@ impl Iterator for ops::Range { where Self: TrustedRandomAccessNoCoerce, { - // SAFETY: The TrustedRandomAccess contract requires that callers only pass an index + // SAFETY: The TrustedRandomAccess contract requires that callers only pass an index // that is in bounds. // Additionally Self: TrustedRandomAccess is only implemented for Copy types // which means even repeated reads of the same index would be safe. diff --git a/library/core/src/iter/sources/empty.rs b/library/core/src/iter/sources/empty.rs index 98734c527..617dfd123 100644 --- a/library/core/src/iter/sources/empty.rs +++ b/library/core/src/iter/sources/empty.rs @@ -22,17 +22,12 @@ pub const fn empty() -> Empty { Empty(marker::PhantomData) } -// Newtype for use in `PhantomData` to avoid -// > error: const-stable function cannot use `#[feature(const_fn_fn_ptr_basics)]` -// in `const fn empty()` above. -struct FnReturning(fn() -> T); - /// An iterator that yields nothing. /// /// This `struct` is created by the [`empty()`] function. See its documentation for more. #[must_use = "iterators are lazy and do nothing unless consumed"] #[stable(feature = "iter_empty", since = "1.2.0")] -pub struct Empty(marker::PhantomData>); +pub struct Empty(marker::PhantomData T>); #[stable(feature = "core_impl_debug", since = "1.9.0")] impl fmt::Debug for Empty { diff --git a/library/core/src/iter/sources/from_generator.rs b/library/core/src/iter/sources/from_generator.rs index 8e7cbd34a..4cbe731b2 100644 --- a/library/core/src/iter/sources/from_generator.rs +++ b/library/core/src/iter/sources/from_generator.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::ops::{Generator, GeneratorState}; use crate::pin::Pin; @@ -23,14 +24,21 @@ use crate::pin::Pin; /// ``` #[inline] #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] -pub fn from_generator + Unpin>( - generator: G, -) -> impl Iterator { +pub fn from_generator + Unpin>(generator: G) -> FromGenerator { FromGenerator(generator) } -struct FromGenerator(G); +/// An iterator over the values yielded by an underlying generator. +/// +/// This `struct` is created by the [`iter::from_generator()`] function. See its documentation for +/// more. +/// +/// [`iter::from_generator()`]: from_generator +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] +#[derive(Clone)] +pub struct FromGenerator(G); +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] impl + Unpin> Iterator for FromGenerator { type Item = G::Yield; @@ -41,3 +49,10 @@ impl + Unpin> Iterator for FromGenerator { } } } + +#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] +impl fmt::Debug for FromGenerator { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("FromGenerator").finish() + } +} diff --git a/library/core/src/iter/sources/once_with.rs b/library/core/src/iter/sources/once_with.rs index d79f85c25..9309a06c8 100644 --- a/library/core/src/iter/sources/once_with.rs +++ b/library/core/src/iter/sources/once_with.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::iter::{FusedIterator, TrustedLen}; /// Creates an iterator that lazily generates a value exactly once by invoking @@ -66,12 +67,23 @@ pub fn once_with A>(gen: F) -> OnceWith { /// /// This `struct` is created by the [`once_with()`] function. /// See its documentation for more. -#[derive(Clone, Debug)] +#[derive(Clone)] #[stable(feature = "iter_once_with", since = "1.43.0")] pub struct OnceWith { gen: Option, } +#[stable(feature = "iter_once_with_debug", since = "1.68.0")] +impl fmt::Debug for OnceWith { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.gen.is_some() { + f.write_str("OnceWith(Some(_))") + } else { + f.write_str("OnceWith(None)") + } + } +} + #[stable(feature = "iter_once_with", since = "1.43.0")] impl A> Iterator for OnceWith { type Item = A; diff --git a/library/core/src/iter/sources/repeat_n.rs b/library/core/src/iter/sources/repeat_n.rs index fd8d25ce1..dc61d6065 100644 --- a/library/core/src/iter/sources/repeat_n.rs +++ b/library/core/src/iter/sources/repeat_n.rs @@ -126,7 +126,7 @@ impl Iterator for RepeatN { // zero so it won't be dropped later, and thus it's okay to take it here. unsafe { ManuallyDrop::take(&mut self.element) } } else { - A::clone(&mut self.element) + A::clone(&self.element) }) } diff --git a/library/core/src/iter/sources/repeat_with.rs b/library/core/src/iter/sources/repeat_with.rs index ab2d0472b..3f34105a3 100644 --- a/library/core/src/iter/sources/repeat_with.rs +++ b/library/core/src/iter/sources/repeat_with.rs @@ -1,3 +1,4 @@ +use crate::fmt; use crate::iter::{FusedIterator, TrustedLen}; use crate::ops::Try; @@ -71,12 +72,19 @@ pub fn repeat_with A>(repeater: F) -> RepeatWith { /// /// This `struct` is created by the [`repeat_with()`] function. /// See its documentation for more. -#[derive(Copy, Clone, Debug)] +#[derive(Copy, Clone)] #[stable(feature = "iterator_repeat_with", since = "1.28.0")] pub struct RepeatWith { repeater: F, } +#[stable(feature = "iterator_repeat_with_debug", since = "1.68.0")] +impl fmt::Debug for RepeatWith { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RepeatWith").finish_non_exhaustive() + } +} + #[stable(feature = "iterator_repeat_with", since = "1.28.0")] impl A> Iterator for RepeatWith { type Item = A; diff --git a/library/core/src/iter/traits/accum.rs b/library/core/src/iter/traits/accum.rs index 84d83ee39..e31669b39 100644 --- a/library/core/src/iter/traits/accum.rs +++ b/library/core/src/iter/traits/accum.rs @@ -10,6 +10,10 @@ use crate::num::Wrapping; /// [`sum()`]: Iterator::sum /// [`FromIterator`]: iter::FromIterator #[stable(feature = "iter_arith_traits", since = "1.12.0")] +#[rustc_on_unimplemented( + message = "a value of type `{Self}` cannot be made by summing an iterator over elements of type `{A}`", + label = "value of type `{Self}` cannot be made by summing a `std::iter::Iterator`" +)] pub trait Sum: Sized { /// Method which takes an iterator and generates `Self` from the elements by /// "summing up" the items. @@ -27,6 +31,10 @@ pub trait Sum: Sized { /// [`product()`]: Iterator::product /// [`FromIterator`]: iter::FromIterator #[stable(feature = "iter_arith_traits", since = "1.12.0")] +#[rustc_on_unimplemented( + message = "a value of type `{Self}` cannot be made by multiplying all elements of type `{A}` from an iterator", + label = "value of type `{Self}` cannot be made by multiplying all elements from a `std::iter::Iterator`" +)] pub trait Product: Sized { /// Method which takes an iterator and generates `Self` from the elements by /// multiplying the items. diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index 83c7e8977..a4a665d48 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -58,6 +58,11 @@ fn _assert_is_object_safe(_: &dyn Iterator) {} note = "if you want to iterate between `start` until a value `end`, use the exclusive range \ syntax `start..end` or the inclusive range syntax `start..=end`" ), + on( + _Self = "{float}", + note = "if you want to iterate between `start` until a value `end`, use the exclusive range \ + syntax `start..end` or the inclusive range syntax `start..=end`" + ), label = "`{Self}` is not an iterator", message = "`{Self}` is not an iterator" )] @@ -66,6 +71,7 @@ fn _assert_is_object_safe(_: &dyn Iterator) {} #[must_use = "iterators are lazy and do nothing unless consumed"] pub trait Iterator { /// The type of the elements being iterated over. + #[rustc_diagnostic_item = "IteratorItem"] #[stable(feature = "rust1", since = "1.0.0")] type Item; @@ -803,7 +809,7 @@ pub trait Iterator { /// (0..5).map(|x| x * 2 + 1) /// .for_each(move |x| tx.send(x).unwrap()); /// - /// let v: Vec<_> = rx.iter().collect(); + /// let v: Vec<_> = rx.iter().collect(); /// assert_eq!(v, vec![1, 3, 5, 7, 9]); /// ``` /// @@ -1380,8 +1386,8 @@ pub trait Iterator { Take::new(self, n) } - /// An iterator adapter similar to [`fold`] that holds internal state and - /// produces a new iterator. + /// An iterator adapter which, like [`fold`], holds internal state, but + /// unlike [`fold`], produces a new iterator. /// /// [`fold`]: Iterator::fold /// @@ -1393,20 +1399,25 @@ pub trait Iterator { /// /// On iteration, the closure will be applied to each element of the /// iterator and the return value from the closure, an [`Option`], is - /// yielded by the iterator. + /// returned by the `next` method. Thus the closure can return + /// `Some(value)` to yield `value`, or `None` to end the iteration. /// /// # Examples /// /// Basic usage: /// /// ``` - /// let a = [1, 2, 3]; + /// let a = [1, 2, 3, 4]; /// /// let mut iter = a.iter().scan(1, |state, &x| { - /// // each iteration, we'll multiply the state by the element + /// // each iteration, we'll multiply the state by the element ... /// *state = *state * x; /// - /// // then, we'll yield the negation of the state + /// // ... and terminate if the state exceeds 6 + /// if *state > 6 { + /// return None; + /// } + /// // ... else yield the negation of the state /// Some(-*state) /// }); /// @@ -1508,6 +1519,18 @@ pub trait Iterator { /// assert_eq!(merged, "alphabetagamma"); /// ``` /// + /// Flattening works on any `IntoIterator` type, including `Option` and `Result`: + /// + /// ``` + /// let options = vec![Some(123), Some(321), None, Some(231)]; + /// let flattened_options: Vec<_> = options.into_iter().flatten().collect(); + /// assert_eq!(flattened_options, vec![123, 321, 231]); + /// + /// let results = vec![Ok(123), Ok(321), Err(456), Ok(231)]; + /// let flattened_results: Vec<_> = results.into_iter().flatten().collect(); + /// assert_eq!(flattened_results, vec![123, 321, 231]); + /// ``` + /// /// Flattening only removes one level of nesting at a time: /// /// ``` @@ -1829,6 +1852,7 @@ pub trait Iterator { #[inline] #[stable(feature = "rust1", since = "1.0.0")] #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"] + #[cfg_attr(not(test), rustc_diagnostic_item = "iterator_collect_fn")] fn collect>(self) -> B where Self: Sized, @@ -2652,7 +2676,10 @@ pub trait Iterator { /// argument is a double reference. You can see this effect in the /// examples below, with `&&x`. /// + /// If you need the index of the element, see [`position()`]. + /// /// [`Some(element)`]: Some + /// [`position()`]: Iterator::position /// /// # Examples /// @@ -2733,7 +2760,7 @@ pub trait Iterator { /// the first true result or the first error. /// /// The return type of this method depends on the return type of the closure. - /// If you return `Result` from the closure, you'll get a `Result; E>`. + /// If you return `Result` from the closure, you'll get a `Result, E>`. /// If you return `Option` from the closure, you'll get an `Option>`. /// /// # Examples diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs index 1823fd300..8790649ab 100644 --- a/library/core/src/lib.rs +++ b/library/core/src/lib.rs @@ -38,18 +38,18 @@ //! which do not trigger a panic can be assured that this function is never //! called. The `lang` attribute is called `eh_personality`. -// Since libcore defines many fundamental lang items, all tests live in a -// separate crate, libcoretest, to avoid bizarre issues. +// Since core defines many fundamental lang items, all tests live in a +// separate crate, libcoretest (library/core/tests), to avoid bizarre issues. // // Here we explicitly #[cfg]-out this whole crate when testing. If we don't do // this, both the generated test artifact and the linked libtest (which -// transitively includes libcore) will both define the same set of lang items, +// transitively includes core) will both define the same set of lang items, // and this will cause the E0152 "found duplicate lang item" error. See // discussion in #50466 for details. // // This cfg won't affect doc tests. #![cfg(not(test))] -// To run libcore tests without x.py without ending up with two copies of libcore, Miri needs to be +// To run core tests without x.py without ending up with two copies of core, Miri needs to be // able to "empty" this crate. See . // rustc itself never sets the feature, so this line has no affect there. #![cfg(any(not(feature = "miri-test-libstd"), test, doctest))] @@ -158,6 +158,7 @@ #![feature(const_unsafecell_get_mut)] #![feature(const_waker)] #![feature(core_panic)] +#![feature(char_indices_offset)] #![feature(duration_consts_float)] #![feature(maybe_uninit_uninit_array)] #![feature(ptr_alignment_type)] @@ -166,6 +167,8 @@ #![feature(slice_ptr_get)] #![feature(slice_split_at_unchecked)] #![feature(str_internals)] +#![feature(str_split_remainder)] +#![feature(str_split_inclusive_remainder)] #![feature(strict_provenance)] #![feature(utf16_extra)] #![feature(utf16_extra_const)] @@ -188,13 +191,14 @@ #![feature(cfg_sanitize)] #![feature(cfg_target_has_atomic)] #![feature(cfg_target_has_atomic_equal_alignment)] +#![cfg_attr(not(bootstrap), feature(const_closures))] #![feature(const_fn_floating_point_arithmetic)] #![feature(const_mut_refs)] #![feature(const_precise_live_drops)] #![feature(const_refs_to_cell)] #![feature(decl_macro)] #![feature(deprecated_suggestion)] -#![cfg_attr(not(bootstrap), feature(derive_const))] +#![feature(derive_const)] #![feature(doc_cfg)] #![feature(doc_notable_trait)] #![feature(rustdoc_internals)] @@ -236,7 +240,6 @@ #![feature(arm_target_feature)] #![feature(avx512_target_feature)] #![feature(cmpxchg16b_target_feature)] -#![feature(f16c_target_feature)] #![feature(hexagon_target_feature)] #![feature(mips_target_feature)] #![feature(powerpc_target_feature)] @@ -245,6 +248,7 @@ #![feature(sse4a_target_feature)] #![feature(tbm_target_feature)] #![feature(wasm_target_feature)] +#![cfg_attr(bootstrap, feature(f16c_target_feature))] // allow using `core::` in intra-doc links #[allow(unused_extern_crates)] @@ -309,7 +313,7 @@ pub mod f64; #[macro_use] pub mod num; -/* The libcore prelude, not as all-encompassing as the libstd prelude */ +/* The core prelude, not as all-encompassing as the std prelude */ pub mod prelude; @@ -376,12 +380,12 @@ mod const_closure; #[stable(feature = "core_primitive", since = "1.43.0")] pub mod primitive; -// Pull in the `core_arch` crate directly into libcore. The contents of +// Pull in the `core_arch` crate directly into core. The contents of // `core_arch` are in a different repository: rust-lang/stdarch. // -// `core_arch` depends on libcore, but the contents of this module are +// `core_arch` depends on core, but the contents of this module are // set up in such a way that directly pulling it here works such that the -// crate uses the this crate as its libcore. +// crate uses the this crate as its core. #[path = "../../stdarch/crates/core_arch/src/mod.rs"] #[allow( missing_docs, @@ -400,12 +404,12 @@ mod core_arch; #[stable(feature = "simd_arch", since = "1.27.0")] pub mod arch; -// Pull in the `core_simd` crate directly into libcore. The contents of +// Pull in the `core_simd` crate directly into core. The contents of // `core_simd` are in a different repository: rust-lang/portable-simd. // -// `core_simd` depends on libcore, but the contents of this module are +// `core_simd` depends on core, but the contents of this module are // set up in such a way that directly pulling it here works such that the -// crate uses this crate as its libcore. +// crate uses this crate as its core. #[path = "../../portable-simd/crates/core_simd/src/mod.rs"] #[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn, unused_unsafe)] #[allow(rustdoc::bare_urls)] diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs index f29cd357d..3b026bc0e 100644 --- a/library/core/src/macros/mod.rs +++ b/library/core/src/macros/mod.rs @@ -1315,22 +1315,41 @@ pub(crate) mod builtin { /// 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. + /// **Warning**: For multi-file Rust projects, the `include!` macro is probably not what you + /// are looking for. Usually, multi-file Rust projects use + /// [modules](https://doc.rust-lang.org/reference/items/modules.html). Multi-file projects and + /// modules are explained in the Rust-by-Example book + /// [here](https://doc.rust-lang.org/rust-by-example/mod/split.html) and the module system is + /// explained in the Rust Book + /// [here](https://doc.rust-lang.org/book/ch07-02-defining-modules-to-control-scope-and-privacy.html). + /// + /// The included file is placed in the surrounding code + /// [unhygienically](https://doc.rust-lang.org/reference/macros-by-example.html#hygiene). If + /// the included file is parsed as an expression and variables or functions share names across + /// both files, it could result in variables or functions being different from what the + /// included file expected. + /// + /// The included 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. + /// # Uses + /// + /// The `include!` macro is primarily used for two purposes. It is used to include + /// documentation that is written in a separate file and it is used to include [build artifacts + /// usually as a result from the `build.rs` + /// script](https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script). + /// + /// When using the `include` macro to include stretches of documentation, remember that the + /// included file still needs to be a valid rust syntax. It is also possible to + /// use the [`include_str`] macro as `#![doc = include_str!("...")]` (at the module level) or + /// `#[doc = include_str!("...")]` (at the item level) to include documentation from a plain + /// text or markdown file. /// /// # Examples /// - /// Assume there are two files in the same directory with the following - /// contents: + /// Assume there are two files in the same directory with the following contents: /// /// File 'monkeys.in': /// @@ -1461,7 +1480,6 @@ pub(crate) mod builtin { /// [the reference]: ../../../reference/attributes/derive.html #[unstable(feature = "derive_const", issue = "none")] #[rustc_builtin_macro] - #[cfg(not(bootstrap))] pub macro derive_const($item:item) { /* compiler built-in */ } @@ -1516,7 +1534,6 @@ pub(crate) mod builtin { /// Attribute macro applied to a function to register it as a handler for allocation failure. /// /// See also [`std::alloc::handle_alloc_error`](../../../std/alloc/fn.handle_alloc_error.html). - #[cfg(not(bootstrap))] #[unstable(feature = "alloc_error_handler", issue = "51540")] #[allow_internal_unstable(rustc_attrs)] #[rustc_builtin_macro] @@ -1553,7 +1570,6 @@ pub(crate) mod builtin { issue = "23416", reason = "placeholder syntax for type ascription" )] - #[cfg(not(bootstrap))] pub macro type_ascribe($expr:expr, $ty:ty) { /* compiler built-in */ } diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs index 42c342801..1326fc9ab 100644 --- a/library/core/src/marker.rs +++ b/library/core/src/marker.rs @@ -96,7 +96,7 @@ unsafe impl Send for &T {} )] #[fundamental] // for Default, for example, which requires that `[T]: !Default` be evaluatable #[rustc_specialization_trait] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait Sized { // Empty. } @@ -126,9 +126,9 @@ pub trait Sized { /// [`Rc`]: ../../std/rc/struct.Rc.html /// [RFC982]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md /// [nomicon-coerce]: ../../nomicon/coercions.html -#[unstable(feature = "unsize", issue = "27732")] +#[unstable(feature = "unsize", issue = "18598")] #[lang = "unsize"] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait Unsize { // Empty. } @@ -623,6 +623,12 @@ impl !Sync for *mut T {} /// (ideally) or `PhantomData<*const T>` (if no lifetime applies), so /// as not to indicate ownership. /// +/// ## Layout +/// +/// For all `T`, the following are guaranteed: +/// * `size_of::>() == 0` +/// * `align_of::>() == 1` +/// /// [drop check]: ../../nomicon/dropck.html #[lang = "phantom_data"] #[stable(feature = "rust1", since = "1.0.0")] @@ -695,7 +701,7 @@ impl StructuralEq for PhantomData {} reason = "this trait is unlikely to ever be stabilized, use `mem::discriminant` instead" )] #[lang = "discriminant_kind"] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait DiscriminantKind { /// The type of the discriminant, which must satisfy the trait /// bounds required by `mem::Discriminant`. @@ -796,7 +802,7 @@ impl Unpin for *mut T {} #[lang = "destruct"] #[rustc_on_unimplemented(message = "can't drop `{Self}`", append_const_msg)] #[const_trait] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait Destruct {} /// A marker for tuple types. @@ -806,12 +812,12 @@ pub trait Destruct {} #[unstable(feature = "tuple_trait", issue = "none")] #[lang = "tuple_trait"] #[rustc_on_unimplemented(message = "`{Self}` is not a tuple")] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait Tuple {} /// A marker for things #[unstable(feature = "pointer_sized_trait", issue = "none")] -#[cfg_attr(not(bootstrap), lang = "pointer_sized")] +#[lang = "pointer_sized"] #[rustc_on_unimplemented( message = "`{Self}` needs to be a pointer-sized type", label = "`{Self}` needs to be a pointer-sized type" diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs index 383bdc7b6..5e01ccc07 100644 --- a/library/core/src/mem/mod.rs +++ b/library/core/src/mem/mod.rs @@ -682,7 +682,8 @@ pub unsafe fn zeroed() -> T { pub unsafe fn uninitialized() -> T { // SAFETY: the caller must guarantee that an uninitialized value is valid for `T`. unsafe { - intrinsics::assert_uninit_valid::(); + #[cfg(not(bootstrap))] // If the compiler hits this itself then it deserves the UB. + intrinsics::assert_mem_uninitialized_valid::(); let mut val = MaybeUninit::::uninit(); // Fill memory with 0x01, as an imperfect mitigation for old code that uses this function on diff --git a/library/core/src/num/dec2flt/fpu.rs b/library/core/src/num/dec2flt/fpu.rs index ec5fa45fd..3806977f7 100644 --- a/library/core/src/num/dec2flt/fpu.rs +++ b/library/core/src/num/dec2flt/fpu.rs @@ -26,7 +26,7 @@ mod fpu_precision { /// Developer's Manual (Volume 1). /// /// The only field which is relevant for the following code is PC, Precision Control. This - /// field determines the precision of the operations performed by the FPU. It can be set to: + /// field determines the precision of the operations performed by the FPU. It can be set to: /// - 0b00, single precision i.e., 32-bits /// - 0b10, double precision i.e., 64-bits /// - 0b11, double extended precision i.e., 80-bits (default state) diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs index 2c6a0ba64..1308b0770 100644 --- a/library/core/src/num/f32.rs +++ b/library/core/src/num/f32.rs @@ -428,7 +428,7 @@ impl f32 { self != self } - // FIXME(#50145): `abs` is publicly unavailable in libcore due to + // FIXME(#50145): `abs` is publicly unavailable in core due to // concerns about portability, so this implementation is for // private use internally. #[inline] diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs index fd3c18ce2..2a22c4302 100644 --- a/library/core/src/num/f64.rs +++ b/library/core/src/num/f64.rs @@ -427,7 +427,7 @@ impl f64 { self != self } - // FIXME(#50145): `abs` is publicly unavailable in libcore due to + // FIXME(#50145): `abs` is publicly unavailable in core due to // concerns about portability, so this implementation is for // private use internally. #[inline] diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs index 57096f439..2cae98b8e 100644 --- a/library/core/src/num/int_macros.rs +++ b/library/core/src/num/int_macros.rs @@ -1514,37 +1514,50 @@ macro_rules! int_impl { (a as Self, b) } - /// Calculates `self + rhs + carry` without the ability to overflow. + /// Calculates `self` + `rhs` + `carry` and checks for overflow. /// - /// Performs "signed ternary addition" which takes in an extra bit to add, and may return an - /// additional bit of overflow. This signed function is used only on the highest-ordered data, - /// for which the signed overflow result indicates whether the big integer overflowed or not. + /// Performs "ternary addition" of two integer operands and a carry-in + /// bit, and returns a tuple of the sum along with a boolean indicating + /// whether an arithmetic overflow would occur. On overflow, the wrapped + /// value is returned. /// - /// # Examples + /// This allows chaining together multiple additions to create a wider + /// addition, and can be useful for bignum addition. This method should + /// only be used for the most significant word; for the less significant + /// words the unsigned method + #[doc = concat!("[`", stringify!($UnsignedT), "::carrying_add`]")] + /// should be used. /// - /// Basic usage: + /// The output boolean returned by this method is *not* a carry flag, + /// and should *not* be added to a more significant word. /// - /// ``` - /// #![feature(bigint_helper_methods)] - #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".carrying_add(2, false), (7, false));")] - #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".carrying_add(2, true), (8, false));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.carrying_add(1, false), (", stringify!($SelfT), "::MIN, true));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.carrying_add(0, true), (", stringify!($SelfT), "::MIN, true));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.carrying_add(1, true), (", stringify!($SelfT), "::MIN + 1, true));")] - #[doc = concat!("assert_eq!(", - stringify!($SelfT), "::MAX.carrying_add(", stringify!($SelfT), "::MAX, true), ", - "(-1, true));" - )] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.carrying_add(-1, true), (", stringify!($SelfT), "::MIN, false));")] - #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".carrying_add(", stringify!($SelfT), "::MAX, true), (", stringify!($SelfT), "::MIN, true));")] - /// ``` + /// If the input carry is false, this method is equivalent to + /// [`overflowing_add`](Self::overflowing_add). /// - /// If `carry` is false, this method is equivalent to [`overflowing_add`](Self::overflowing_add): + /// # Examples /// /// ``` /// #![feature(bigint_helper_methods)] - #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".carrying_add(2, false), 5_", stringify!($SelfT), ".overflowing_add(2));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.carrying_add(1, false), ", stringify!($SelfT), "::MAX.overflowing_add(1));")] + /// // Only the most significant word is signed. + /// // + #[doc = concat!("// 10 MAX (a = 10 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")] + #[doc = concat!("// + -5 9 (b = -5 × 2^", stringify!($BITS), " + 9)")] + /// // --------- + #[doc = concat!("// 6 8 (sum = 6 × 2^", stringify!($BITS), " + 8)")] + /// + #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($UnsignedT), ") = (10, ", stringify!($UnsignedT), "::MAX);")] + #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($UnsignedT), ") = (-5, 9);")] + /// let carry0 = false; + /// + #[doc = concat!("// ", stringify!($UnsignedT), "::carrying_add for the less significant words")] + /// let (sum0, carry1) = a0.carrying_add(b0, carry0); + /// assert_eq!(carry1, true); + /// + #[doc = concat!("// ", stringify!($SelfT), "::carrying_add for the most significant word")] + /// let (sum1, overflow) = a1.carrying_add(b1, carry1); + /// assert_eq!(overflow, false); + /// + /// assert_eq!((sum1, sum0), (6, 8)); /// ``` #[unstable(feature = "bigint_helper_methods", issue = "85532")] #[rustc_const_unstable(feature = "const_bigint_helper_methods", issue = "85532")] @@ -1608,25 +1621,51 @@ macro_rules! int_impl { (a as Self, b) } - /// Calculates `self - rhs - borrow` without the ability to overflow. + /// Calculates `self` − `rhs` − `borrow` and checks for + /// overflow. /// - /// Performs "signed ternary subtraction" which takes in an extra bit to subtract, and may return an - /// additional bit of overflow. This signed function is used only on the highest-ordered data, - /// for which the signed overflow result indicates whether the big integer overflowed or not. + /// Performs "ternary subtraction" by subtracting both an integer + /// operand and a borrow-in bit from `self`, and returns a tuple of the + /// difference along with a boolean indicating whether an arithmetic + /// overflow would occur. On overflow, the wrapped value is returned. /// - /// # Examples + /// This allows chaining together multiple subtractions to create a + /// wider subtraction, and can be useful for bignum subtraction. This + /// method should only be used for the most significant word; for the + /// less significant words the unsigned method + #[doc = concat!("[`", stringify!($UnsignedT), "::borrowing_sub`]")] + /// should be used. /// - /// Basic usage: + /// The output boolean returned by this method is *not* a borrow flag, + /// and should *not* be subtracted from a more significant word. + /// + /// If the input borrow is false, this method is equivalent to + /// [`overflowing_sub`](Self::overflowing_sub). + /// + /// # Examples /// /// ``` /// #![feature(bigint_helper_methods)] - #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".borrowing_sub(2, false), (3, false));")] - #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".borrowing_sub(2, true), (2, false));")] - #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".borrowing_sub(1, false), (-1, false));")] - #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".borrowing_sub(1, true), (-2, false));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.borrowing_sub(1, true), (", stringify!($SelfT), "::MAX - 1, true));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.borrowing_sub(-1, false), (", stringify!($SelfT), "::MIN, true));")] - #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.borrowing_sub(-1, true), (", stringify!($SelfT), "::MAX, false));")] + /// // Only the most significant word is signed. + /// // + #[doc = concat!("// 6 8 (a = 6 × 2^", stringify!($BITS), " + 8)")] + #[doc = concat!("// - -5 9 (b = -5 × 2^", stringify!($BITS), " + 9)")] + /// // --------- + #[doc = concat!("// 10 MAX (diff = 10 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")] + /// + #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($UnsignedT), ") = (6, 8);")] + #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($UnsignedT), ") = (-5, 9);")] + /// let borrow0 = false; + /// + #[doc = concat!("// ", stringify!($UnsignedT), "::borrowing_sub for the less significant words")] + /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0); + /// assert_eq!(borrow1, true); + /// + #[doc = concat!("// ", stringify!($SelfT), "::borrowing_sub for the most significant word")] + /// let (diff1, overflow) = a1.borrowing_sub(b1, borrow1); + /// assert_eq!(overflow, false); + /// + #[doc = concat!("assert_eq!((diff1, diff0), (10, ", stringify!($UnsignedT), "::MAX));")] /// ``` #[unstable(feature = "bigint_helper_methods", issue = "85532")] #[rustc_const_unstable(feature = "const_bigint_helper_methods", issue = "85532")] diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs index 127b047db..b7e1aee9d 100644 --- a/library/core/src/ops/function.rs +++ b/library/core/src/ops/function.rs @@ -1,4 +1,3 @@ -#[cfg(not(bootstrap))] use crate::marker::Tuple; /// The version of the call operator that takes an immutable receiver. @@ -54,87 +53,6 @@ use crate::marker::Tuple; /// let double = |x| x * 2; /// assert_eq!(call_with_one(double), 2); /// ``` -#[cfg(bootstrap)] -#[lang = "fn"] -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_paren_sugar] -#[rustc_on_unimplemented( - on( - Args = "()", - note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" - ), - on( - _Self = "unsafe fn", - note = "unsafe function cannot be called generically without an unsafe block", - // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string - label = "call the function in a closure: `|| unsafe {{ /* code */ }}`" - ), - message = "expected a `{Fn}<{Args}>` closure, found `{Self}`", - label = "expected an `Fn<{Args}>` closure, found `{Self}`" -)] -#[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use = "closures are lazy and do nothing unless called"] -#[const_trait] -pub trait Fn: FnMut { - /// Performs the call operation. - #[unstable(feature = "fn_traits", issue = "29625")] - extern "rust-call" fn call(&self, args: Args) -> Self::Output; -} - -/// The version of the call operator that takes an immutable receiver. -/// -/// Instances of `Fn` can be called repeatedly without mutating state. -/// -/// *This trait (`Fn`) is not to be confused with [function pointers] -/// (`fn`).* -/// -/// `Fn` is implemented automatically by closures which only take immutable -/// references to captured variables or don't capture anything at all, as well -/// as (safe) [function pointers] (with some caveats, see their documentation -/// for more details). Additionally, for any type `F` that implements `Fn`, `&F` -/// implements `Fn`, too. -/// -/// Since both [`FnMut`] and [`FnOnce`] are supertraits of `Fn`, any -/// instance of `Fn` can be used as a parameter where a [`FnMut`] or [`FnOnce`] -/// is expected. -/// -/// Use `Fn` as a bound when you want to accept a parameter of function-like -/// type and need to call it repeatedly and without mutating state (e.g., when -/// calling it concurrently). If you do not need such strict requirements, use -/// [`FnMut`] or [`FnOnce`] as bounds. -/// -/// See the [chapter on closures in *The Rust Programming Language*][book] for -/// some more information on this topic. -/// -/// Also of note is the special syntax for `Fn` traits (e.g. -/// `Fn(usize, bool) -> usize`). Those interested in the technical details of -/// this can refer to [the relevant section in the *Rustonomicon*][nomicon]. -/// -/// [book]: ../../book/ch13-01-closures.html -/// [function pointers]: fn -/// [nomicon]: ../../nomicon/hrtb.html -/// -/// # Examples -/// -/// ## Calling a closure -/// -/// ``` -/// let square = |x| x * x; -/// assert_eq!(square(5), 25); -/// ``` -/// -/// ## Using a `Fn` parameter -/// -/// ``` -/// fn call_with_one(func: F) -> usize -/// where F: Fn(usize) -> usize { -/// func(1) -/// } -/// -/// let double = |x| x * 2; -/// assert_eq!(call_with_one(double), 2); -/// ``` -#[cfg(not(bootstrap))] #[lang = "fn"] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_paren_sugar] @@ -222,95 +140,6 @@ pub trait Fn: FnMut { /// /// assert_eq!(x, 5); /// ``` -#[cfg(bootstrap)] -#[lang = "fn_mut"] -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_paren_sugar] -#[rustc_on_unimplemented( - on( - Args = "()", - note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" - ), - on( - _Self = "unsafe fn", - note = "unsafe function cannot be called generically without an unsafe block", - // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string - label = "call the function in a closure: `|| unsafe {{ /* code */ }}`" - ), - message = "expected a `{FnMut}<{Args}>` closure, found `{Self}`", - label = "expected an `FnMut<{Args}>` closure, found `{Self}`" -)] -#[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use = "closures are lazy and do nothing unless called"] -#[const_trait] -pub trait FnMut: FnOnce { - /// Performs the call operation. - #[unstable(feature = "fn_traits", issue = "29625")] - extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output; -} - -/// The version of the call operator that takes a mutable receiver. -/// -/// Instances of `FnMut` can be called repeatedly and may mutate state. -/// -/// `FnMut` is implemented automatically by closures which take mutable -/// references to captured variables, as well as all types that implement -/// [`Fn`], e.g., (safe) [function pointers] (since `FnMut` is a supertrait of -/// [`Fn`]). Additionally, for any type `F` that implements `FnMut`, `&mut F` -/// implements `FnMut`, too. -/// -/// Since [`FnOnce`] is a supertrait of `FnMut`, any instance of `FnMut` can be -/// used where a [`FnOnce`] is expected, and since [`Fn`] is a subtrait of -/// `FnMut`, any instance of [`Fn`] can be used where `FnMut` is expected. -/// -/// Use `FnMut` as a bound when you want to accept a parameter of function-like -/// type and need to call it repeatedly, while allowing it to mutate state. -/// If you don't want the parameter to mutate state, use [`Fn`] as a -/// bound; if you don't need to call it repeatedly, use [`FnOnce`]. -/// -/// See the [chapter on closures in *The Rust Programming Language*][book] for -/// some more information on this topic. -/// -/// Also of note is the special syntax for `Fn` traits (e.g. -/// `Fn(usize, bool) -> usize`). Those interested in the technical details of -/// this can refer to [the relevant section in the *Rustonomicon*][nomicon]. -/// -/// [book]: ../../book/ch13-01-closures.html -/// [function pointers]: fn -/// [nomicon]: ../../nomicon/hrtb.html -/// -/// # Examples -/// -/// ## Calling a mutably capturing closure -/// -/// ``` -/// let mut x = 5; -/// { -/// let mut square_x = || x *= x; -/// square_x(); -/// } -/// assert_eq!(x, 25); -/// ``` -/// -/// ## Using a `FnMut` parameter -/// -/// ``` -/// fn do_twice(mut func: F) -/// where F: FnMut() -/// { -/// func(); -/// func(); -/// } -/// -/// let mut x: usize = 1; -/// { -/// let add_two_to_x = || x += 2; -/// do_twice(add_two_to_x); -/// } -/// -/// assert_eq!(x, 5); -/// ``` -#[cfg(not(bootstrap))] #[lang = "fn_mut"] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_paren_sugar] @@ -390,92 +219,6 @@ pub trait FnMut: FnOnce { /// /// // `consume_and_return_x` can no longer be invoked at this point /// ``` -#[cfg(bootstrap)] -#[lang = "fn_once"] -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_paren_sugar] -#[rustc_on_unimplemented( - on( - Args = "()", - note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" - ), - on( - _Self = "unsafe fn", - note = "unsafe function cannot be called generically without an unsafe block", - // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string - label = "call the function in a closure: `|| unsafe {{ /* code */ }}`" - ), - message = "expected a `{FnOnce}<{Args}>` closure, found `{Self}`", - label = "expected an `FnOnce<{Args}>` closure, found `{Self}`" -)] -#[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use = "closures are lazy and do nothing unless called"] -#[const_trait] -pub trait FnOnce { - /// The returned type after the call operator is used. - #[lang = "fn_once_output"] - #[stable(feature = "fn_once_output", since = "1.12.0")] - type Output; - - /// Performs the call operation. - #[unstable(feature = "fn_traits", issue = "29625")] - extern "rust-call" fn call_once(self, args: Args) -> Self::Output; -} - -/// The version of the call operator that takes a by-value receiver. -/// -/// Instances of `FnOnce` can be called, but might not be callable multiple -/// times. Because of this, if the only thing known about a type is that it -/// implements `FnOnce`, it can only be called once. -/// -/// `FnOnce` is implemented automatically by closures that might consume captured -/// variables, as well as all types that implement [`FnMut`], e.g., (safe) -/// [function pointers] (since `FnOnce` is a supertrait of [`FnMut`]). -/// -/// Since both [`Fn`] and [`FnMut`] are subtraits of `FnOnce`, any instance of -/// [`Fn`] or [`FnMut`] can be used where a `FnOnce` is expected. -/// -/// Use `FnOnce` as a bound when you want to accept a parameter of function-like -/// type and only need to call it once. If you need to call the parameter -/// repeatedly, use [`FnMut`] as a bound; if you also need it to not mutate -/// state, use [`Fn`]. -/// -/// See the [chapter on closures in *The Rust Programming Language*][book] for -/// some more information on this topic. -/// -/// Also of note is the special syntax for `Fn` traits (e.g. -/// `Fn(usize, bool) -> usize`). Those interested in the technical details of -/// this can refer to [the relevant section in the *Rustonomicon*][nomicon]. -/// -/// [book]: ../../book/ch13-01-closures.html -/// [function pointers]: fn -/// [nomicon]: ../../nomicon/hrtb.html -/// -/// # Examples -/// -/// ## Using a `FnOnce` parameter -/// -/// ``` -/// fn consume_with_relish(func: F) -/// where F: FnOnce() -> String -/// { -/// // `func` consumes its captured variables, so it cannot be run more -/// // than once. -/// println!("Consumed: {}", func()); -/// -/// println!("Delicious!"); -/// -/// // Attempting to invoke `func()` again will throw a `use of moved -/// // value` error for `func`. -/// } -/// -/// let x = String::from("x"); -/// let consume_and_return_x = move || x; -/// consume_with_relish(consume_and_return_x); -/// -/// // `consume_and_return_x` can no longer be invoked at this point -/// ``` -#[cfg(not(bootstrap))] #[lang = "fn_once"] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_paren_sugar] @@ -507,68 +250,6 @@ pub trait FnOnce { extern "rust-call" fn call_once(self, args: Args) -> Self::Output; } -#[cfg(bootstrap)] -mod impls { - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_fn_trait_ref_impls", issue = "101803")] - impl const Fn for &F - where - F: ~const Fn, - { - extern "rust-call" fn call(&self, args: A) -> F::Output { - (**self).call(args) - } - } - - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_fn_trait_ref_impls", issue = "101803")] - impl const FnMut for &F - where - F: ~const Fn, - { - extern "rust-call" fn call_mut(&mut self, args: A) -> F::Output { - (**self).call(args) - } - } - - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_fn_trait_ref_impls", issue = "101803")] - impl const FnOnce for &F - where - F: ~const Fn, - { - type Output = F::Output; - - extern "rust-call" fn call_once(self, args: A) -> F::Output { - (*self).call(args) - } - } - - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_fn_trait_ref_impls", issue = "101803")] - impl const FnMut for &mut F - where - F: ~const FnMut, - { - extern "rust-call" fn call_mut(&mut self, args: A) -> F::Output { - (*self).call_mut(args) - } - } - - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_fn_trait_ref_impls", issue = "101803")] - impl const FnOnce for &mut F - where - F: ~const FnMut, - { - type Output = F::Output; - extern "rust-call" fn call_once(self, args: A) -> F::Output { - (*self).call_mut(args) - } - } -} - -#[cfg(not(bootstrap))] mod impls { use crate::marker::Tuple; diff --git a/library/core/src/ops/index.rs b/library/core/src/ops/index.rs index 5e3dc48b6..228efb0bc 100644 --- a/library/core/src/ops/index.rs +++ b/library/core/src/ops/index.rs @@ -165,7 +165,7 @@ see chapter in The Book : Index { +pub trait IndexMut: ~const Index { /// Performs the mutable indexing (`container[index]`) operation. /// /// # Panics diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs index a5e5b13b3..97d9b750d 100644 --- a/library/core/src/ops/mod.rs +++ b/library/core/src/ops/mod.rs @@ -17,10 +17,10 @@ //! should have some resemblance to multiplication (and share expected //! properties like associativity). //! -//! Note that the `&&` and `||` operators short-circuit, i.e., they only -//! evaluate their second operand if it contributes to the result. Since this -//! behavior is not enforceable by traits, `&&` and `||` are not supported as -//! overloadable operators. +//! Note that the `&&` and `||` operators are currently not supported for +//! overloading. Due to their short circuiting nature, they require a different +//! design from traits for other operators like [`BitAnd`]. Designs for them are +//! under discussion. //! //! Many of the operators take their operands by value. In non-generic //! contexts involving built-in types, this is usually not a problem. @@ -201,7 +201,7 @@ pub(crate) use self::try_trait::{ChangeOutputType, NeverShortCircuit}; #[unstable(feature = "generator_trait", issue = "43122")] pub use self::generator::{Generator, GeneratorState}; -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] pub use self::unsize::CoerceUnsized; #[unstable(feature = "dispatch_from_dyn", issue = "none")] diff --git a/library/core/src/ops/unsize.rs b/library/core/src/ops/unsize.rs index a920b9165..b51f12580 100644 --- a/library/core/src/ops/unsize.rs +++ b/library/core/src/ops/unsize.rs @@ -31,41 +31,41 @@ use crate::marker::Unsize; /// [dst-coerce]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md /// [unsize]: crate::marker::Unsize /// [nomicon-coerce]: ../../nomicon/coercions.html -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] #[lang = "coerce_unsized"] pub trait CoerceUnsized { // Empty. } // &mut T -> &mut U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {} // &mut T -> &U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, 'b: 'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {} // &mut T -> *mut U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {} // &mut T -> *const U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {} // &T -> &U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, 'b: 'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<&'a U> for &'b T {} // &T -> *const U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl<'a, T: ?Sized + Unsize, U: ?Sized> CoerceUnsized<*const U> for &'a T {} // *mut T -> *mut U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U: ?Sized> CoerceUnsized<*mut U> for *mut T {} // *mut T -> *const U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U: ?Sized> CoerceUnsized<*const U> for *mut T {} // *const T -> *const U -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl, U: ?Sized> CoerceUnsized<*const U> for *const T {} /// `DispatchFromDyn` is used in the implementation of object safety checks (specifically allowing diff --git a/library/core/src/option.rs b/library/core/src/option.rs index 505d964e5..7cc00e3f8 100644 --- a/library/core/src/option.rs +++ b/library/core/src/option.rs @@ -72,6 +72,50 @@ //! } //! ``` //! +//! # The question mark operator, `?` +//! +//! Similar to the [`Result`] type, when writing code that calls many functions that return the +//! [`Option`] type, handling `Some`/`None` can be tedious. The question mark +//! operator, [`?`], hides some of the boilerplate of propagating values +//! up the call stack. +//! +//! It replaces this: +//! +//! ``` +//! # #![allow(dead_code)] +//! fn add_last_numbers(stack: &mut Vec) -> Option { +//! let a = stack.pop(); +//! let b = stack.pop(); +//! +//! match (a, b) { +//! (Some(x), Some(y)) => Some(x + y), +//! _ => None, +//! } +//! } +//! +//! ``` +//! +//! With this: +//! +//! ``` +//! # #![allow(dead_code)] +//! fn add_last_numbers(stack: &mut Vec) -> Option { +//! Some(stack.pop()? + stack.pop()?) +//! } +//! ``` +//! +//! *It's much nicer!* +//! +//! Ending the expression with [`?`] will result in the [`Some`]'s unwrapped value, unless the +//! result is [`None`], in which case [`None`] is returned early from the enclosing function. +//! +//! [`?`] can be used in functions that return [`Option`] because of the +//! early return of [`None`] that it provides. +//! +//! [`?`]: crate::ops::Try +//! [`Some`]: Some +//! [`None`]: None +//! //! # Representation //! //! Rust guarantees to optimize the following types `T` such that @@ -608,13 +652,14 @@ impl Option { /// /// # Examples /// - /// Converts an Option<[String]> into an Option<[usize]>, preserving - /// the original. The [`map`] method takes the `self` argument by value, consuming the original, - /// so this technique uses `as_ref` to first take an `Option` to a reference - /// to the value inside the original. + /// Calculates the length of an Option<[String]> as an Option<[usize]> + /// without moving the [`String`]. The [`map`] method takes the `self` argument by value, + /// consuming the original, so this technique uses `as_ref` to first take an `Option` to a + /// reference to the value inside the original. /// /// [`map`]: Option::map /// [String]: ../../std/string/struct.String.html "String" + /// [`String`]: ../../std/string/struct.String.html "String" /// /// ``` /// let text: Option = Some("Hello, world!".to_string()); @@ -902,8 +947,8 @@ impl Option { /// /// # Examples /// - /// Converts an Option<[String]> into an Option<[usize]>, consuming - /// the original: + /// Calculates the length of an Option<[String]> as an + /// Option<[usize]>, consuming the original: /// /// [String]: ../../std/string/struct.String.html "String" /// ``` diff --git a/library/core/src/panic.rs b/library/core/src/panic.rs index 461b70c32..8338a5d7e 100644 --- a/library/core/src/panic.rs +++ b/library/core/src/panic.rs @@ -90,14 +90,14 @@ pub macro unreachable_2021 { ), } -/// An internal trait used by libstd to pass data from libstd to `panic_unwind` -/// and other panic runtimes. Not intended to be stabilized any time soon, do -/// not use. +/// An internal trait used by std to pass data from std to `panic_unwind` and +/// other panic runtimes. Not intended to be stabilized any time soon, do not +/// use. #[unstable(feature = "std_internals", issue = "none")] #[doc(hidden)] pub unsafe trait BoxMeUp { /// Take full ownership of the contents. - /// The return type is actually `Box`, but we cannot use `Box` in libcore. + /// The return type is actually `Box`, but we cannot use `Box` in core. /// /// After this method got called, only some dummy default value is left in `self`. /// Calling this method twice, or calling `get` after calling this method, is an error. diff --git a/library/core/src/panic/panic_info.rs b/library/core/src/panic/panic_info.rs index 1923155eb..0d385c9d1 100644 --- a/library/core/src/panic/panic_info.rs +++ b/library/core/src/panic/panic_info.rs @@ -157,7 +157,7 @@ impl fmt::Display for PanicInfo<'_> { write!(formatter, "'{}', ", payload)? } // NOTE: we cannot use downcast_ref::() here - // since String is not available in libcore! + // since String is not available in core! // The payload is a String when `std::panic!` is called with multiple arguments, // but in that case the message is also available. diff --git a/library/core/src/panicking.rs b/library/core/src/panicking.rs index a704a00fa..48e90e6d7 100644 --- a/library/core/src/panicking.rs +++ b/library/core/src/panicking.rs @@ -1,8 +1,8 @@ -//! Panic support for libcore +//! Panic support for core //! //! The core library cannot define panicking, but it does *declare* panicking. This -//! means that the functions inside of libcore are allowed to panic, but to be -//! useful an upstream crate must define panicking for libcore to use. The current +//! means that the functions inside of core are allowed to panic, but to be +//! useful an upstream crate must define panicking for core to use. The current //! interface for panicking is: //! //! ``` @@ -13,7 +13,7 @@ //! This definition allows for panicking with any general message, but it does not //! allow for failing with a `Box` value. (`PanicInfo` just contains a `&(dyn Any + Send)`, //! for which we fill in a dummy value in `PanicInfo::internal_constructor`.) -//! The reason for this is that libcore is not allowed to allocate. +//! The reason for this is that core is not allowed to allocate. //! //! This module contains a few other panicking functions, but these are just the //! necessary lang items for the compiler. All panics are funneled through this @@ -64,12 +64,17 @@ pub const fn panic_fmt(fmt: fmt::Arguments<'_>) -> ! { unsafe { panic_impl(&pi) } } -/// Like panic_fmt, but without unwinding and track_caller to reduce the impact on codesize. -/// Also just works on `str`, as a `fmt::Arguments` needs more space to be passed. +/// Like `panic_fmt`, but for non-unwinding panics. +/// +/// Has to be a separate function so that it can carry the `rustc_nounwind` attribute. #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)] #[cfg_attr(feature = "panic_immediate_abort", inline)] +#[track_caller] +// This attribute has the key side-effect that if the panic handler ignores `can_unwind` +// and unwinds anyway, we will hit the "unwinding out of nounwind function" guard, +// which causes a "panic in a function that cannot unwind". #[rustc_nounwind] -pub fn panic_str_nounwind(msg: &'static str) -> ! { +pub fn panic_nounwind_fmt(fmt: fmt::Arguments<'_>) -> ! { if cfg!(feature = "panic_immediate_abort") { super::intrinsics::abort() } @@ -82,8 +87,6 @@ pub fn panic_str_nounwind(msg: &'static str) -> ! { } // PanicInfo with the `can_unwind` flag set to false forces an abort. - let pieces = [msg]; - let fmt = fmt::Arguments::new_v1(&pieces, &[]); let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), false); // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call. @@ -93,7 +96,7 @@ pub fn panic_str_nounwind(msg: &'static str) -> ! { // Next we define a bunch of higher-level wrappers that all bottom out in the two core functions // above. -/// The underlying implementation of libcore's `panic!` macro when no formatting is used. +/// The underlying implementation of core's `panic!` macro when no formatting is used. // never inline unless panic_immediate_abort to avoid code // bloat at the call sites as much as possible #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)] @@ -111,6 +114,15 @@ pub const fn panic(expr: &'static str) -> ! { panic_fmt(fmt::Arguments::new_v1(&[expr], &[])); } +/// Like `panic`, but without unwinding and track_caller to reduce the impact on codesize. +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cfg_attr(not(bootstrap), lang = "panic_nounwind")] // needed by codegen for non-unwinding panics +#[rustc_nounwind] +pub fn panic_nounwind(expr: &'static str) -> ! { + panic_nounwind_fmt(fmt::Arguments::new_v1(&[expr], &[])); +} + #[inline] #[track_caller] #[rustc_diagnostic_item = "panic_str"] @@ -153,10 +165,11 @@ fn panic_bounds_check(index: usize, len: usize) -> ! { /// any extra arguments (including those synthesized by track_caller). #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)] #[cfg_attr(feature = "panic_immediate_abort", inline)] -#[lang = "panic_no_unwind"] // needed by codegen for panic in nounwind function +#[cfg_attr(bootstrap, lang = "panic_no_unwind")] // needed by codegen for panic in nounwind function +#[cfg_attr(not(bootstrap), lang = "panic_cannot_unwind")] // needed by codegen for panic in nounwind function #[rustc_nounwind] -fn panic_no_unwind() -> ! { - panic_str_nounwind("panic in a function that cannot unwind") +fn panic_cannot_unwind() -> ! { + panic_nounwind("panic in a function that cannot unwind") } /// This function is used instead of panic_fmt in const eval. diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs index 4524fa4c4..febe57dc9 100644 --- a/library/core/src/pin.rs +++ b/library/core/src/pin.rs @@ -485,6 +485,16 @@ impl> Pin

{ /// /// Unlike `Pin::new_unchecked`, this method is safe because the pointer /// `P` dereferences to an [`Unpin`] type, which cancels the pinning guarantees. + /// + /// # Examples + /// + /// ``` + /// use std::pin::Pin; + /// + /// let mut val: u8 = 5; + /// // We can pin the value, since it doesn't care about being moved + /// let mut pinned: Pin<&mut u8> = Pin::new(&mut val); + /// ``` #[inline(always)] #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin", since = "1.33.0")] @@ -496,8 +506,20 @@ impl> Pin

{ /// Unwraps this `Pin

` returning the underlying pointer. /// - /// This requires that the data inside this `Pin` is [`Unpin`] so that we + /// This requires that the data inside this `Pin` implements [`Unpin`] so that we /// can ignore the pinning invariants when unwrapping it. + /// + /// # Examples + /// + /// ``` + /// use std::pin::Pin; + /// + /// let mut val: u8 = 5; + /// let pinned: Pin<&mut u8> = Pin::new(&mut val); + /// // Unwrap the pin to get a reference to the value + /// let r = Pin::into_inner(pinned); + /// assert_eq!(*r, 5); + /// ``` #[inline(always)] #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin_into_inner", since = "1.39.0")] @@ -600,9 +622,8 @@ impl Pin

{ /// that the closure is pinned. /// /// The better alternative is to avoid all that trouble and do the pinning in the outer function - /// instead (here using the unstable `pin` macro): + /// instead (here using the [`pin!`][crate::pin::pin] macro): /// ``` - /// #![feature(pin_macro)] /// use std::pin::pin; /// use std::task::Context; /// use std::future::Future; @@ -707,6 +728,18 @@ impl Pin

{ /// /// This overwrites pinned data, but that is okay: its destructor gets /// run before being overwritten, so no pinning guarantee is violated. + /// + /// # Example + /// + /// ``` + /// use std::pin::Pin; + /// + /// let mut val: u8 = 5; + /// let mut pinned: Pin<&mut u8> = Pin::new(&mut val); + /// println!("{}", pinned); // 5 + /// pinned.as_mut().set(10); + /// println!("{}", pinned); // 10 + /// ``` #[stable(feature = "pin", since = "1.33.0")] #[inline(always)] pub fn set(&mut self, value: P::Target) @@ -720,7 +753,7 @@ impl Pin

{ impl<'a, T: ?Sized> Pin<&'a T> { /// Constructs a new pin by mapping the interior value. /// - /// For example, if you wanted to get a `Pin` of a field of something, + /// For example, if you wanted to get a `Pin` of a field of something, /// you could use this to get access to that field in one line of code. /// However, there are several gotchas with these "pinning projections"; /// see the [`pin` module] documentation for further details on that topic. @@ -823,7 +856,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> { /// Construct a new pin by mapping the interior value. /// - /// For example, if you wanted to get a `Pin` of a field of something, + /// For example, if you wanted to get a `Pin` of a field of something, /// you could use this to get access to that field in one line of code. /// However, there are several gotchas with these "pinning projections"; /// see the [`pin` module] documentation for further details on that topic. @@ -992,7 +1025,6 @@ impl DispatchFromDyn> for Pin

where P: DispatchFromDyn {} /// ### Basic usage /// /// ```rust -/// #![feature(pin_macro)] /// # use core::marker::PhantomPinned as Foo; /// use core::pin::{pin, Pin}; /// @@ -1010,7 +1042,6 @@ impl DispatchFromDyn> for Pin

where P: DispatchFromDyn {} /// ### Manually polling a `Future` (without `Unpin` bounds) /// /// ```rust -/// #![feature(pin_macro)] /// use std::{ /// future::Future, /// pin::pin, @@ -1049,7 +1080,7 @@ impl DispatchFromDyn> for Pin

where P: DispatchFromDyn {} /// ### With `Generator`s /// /// ```rust -/// #![feature(generators, generator_trait, pin_macro)] +/// #![feature(generators, generator_trait)] /// use core::{ /// ops::{Generator, GeneratorState}, /// pin::pin, @@ -1092,7 +1123,6 @@ impl DispatchFromDyn> for Pin

where P: DispatchFromDyn {} /// The following, for instance, fails to compile: /// /// ```rust,compile_fail -/// #![feature(pin_macro)] /// use core::pin::{pin, Pin}; /// # use core::{marker::PhantomPinned as Foo, mem::drop as stuff}; /// @@ -1134,7 +1164,7 @@ impl DispatchFromDyn> for Pin

where P: DispatchFromDyn {} /// constructor. /// /// [`Box::pin`]: ../../std/boxed/struct.Box.html#method.pin -#[unstable(feature = "pin_macro", issue = "93178")] +#[stable(feature = "pin_macro", since = "1.68.0")] #[rustc_macro_transparency = "semitransparent"] #[allow_internal_unstable(unsafe_pin_internals)] pub macro pin($value:expr $(,)?) { diff --git a/library/core/src/prelude/mod.rs b/library/core/src/prelude/mod.rs index 3cd3a3b78..12f762ef1 100644 --- a/library/core/src/prelude/mod.rs +++ b/library/core/src/prelude/mod.rs @@ -1,8 +1,8 @@ -//! The libcore prelude +//! The core prelude //! -//! This module is intended for users of libcore which do not link to libstd as -//! well. This module is imported by default when `#![no_std]` is used in the -//! same manner as the standard library's prelude. +//! This module is intended for users of core which do not link to std as well. +//! This module is imported by default when `#![no_std]` is used in the same +//! manner as the standard library's prelude. #![stable(feature = "core_prelude", since = "1.4.0")] diff --git a/library/core/src/prelude/v1.rs b/library/core/src/prelude/v1.rs index 2d67d742c..10525a16f 100644 --- a/library/core/src/prelude/v1.rs +++ b/library/core/src/prelude/v1.rs @@ -75,14 +75,12 @@ pub use crate::macros::builtin::{RustcDecodable, RustcEncodable}; // Do not `doc(no_inline)` so that they become doc items on their own // (no public module for them to be re-exported from). -#[cfg(not(bootstrap))] #[stable(feature = "builtin_macro_prelude", since = "1.38.0")] -pub use crate::macros::builtin::alloc_error_handler; -#[stable(feature = "builtin_macro_prelude", since = "1.38.0")] -pub use crate::macros::builtin::{bench, derive, global_allocator, test, test_case}; +pub use crate::macros::builtin::{ + alloc_error_handler, bench, derive, global_allocator, test, test_case, +}; #[unstable(feature = "derive_const", issue = "none")] -#[cfg(not(bootstrap))] pub use crate::macros::builtin::derive_const; #[unstable( @@ -104,5 +102,4 @@ pub use crate::macros::builtin::cfg_eval; issue = "23416", reason = "placeholder syntax for type ascription" )] -#[cfg(not(bootstrap))] pub use crate::macros::builtin::type_ascribe; diff --git a/library/core/src/ptr/alignment.rs b/library/core/src/ptr/alignment.rs index 64a5290c3..2123147c7 100644 --- a/library/core/src/ptr/alignment.rs +++ b/library/core/src/ptr/alignment.rs @@ -10,8 +10,7 @@ use crate::{cmp, fmt, hash, mem, num}; /// are likely not to be supported by actual allocators and linkers. #[unstable(feature = "ptr_alignment_type", issue = "102070")] #[derive(Copy, Clone, Eq)] -#[cfg_attr(bootstrap, derive(PartialEq))] -#[cfg_attr(not(bootstrap), derive_const(PartialEq))] +#[derive_const(PartialEq)] #[repr(transparent)] pub struct Alignment(AlignmentEnum); @@ -203,8 +202,7 @@ type AlignmentEnum = AlignmentEnum32; type AlignmentEnum = AlignmentEnum64; #[derive(Copy, Clone, Eq)] -#[cfg_attr(bootstrap, derive(PartialEq))] -#[cfg_attr(not(bootstrap), derive_const(PartialEq))] +#[derive_const(PartialEq)] #[repr(u16)] enum AlignmentEnum16 { _Align1Shl0 = 1 << 0, @@ -226,8 +224,7 @@ enum AlignmentEnum16 { } #[derive(Copy, Clone, Eq)] -#[cfg_attr(bootstrap, derive(PartialEq))] -#[cfg_attr(not(bootstrap), derive_const(PartialEq))] +#[derive_const(PartialEq)] #[repr(u32)] enum AlignmentEnum32 { _Align1Shl0 = 1 << 0, @@ -265,8 +262,7 @@ enum AlignmentEnum32 { } #[derive(Copy, Clone, Eq)] -#[cfg_attr(bootstrap, derive(PartialEq))] -#[cfg_attr(not(bootstrap), derive_const(PartialEq))] +#[derive_const(PartialEq)] #[repr(u64)] enum AlignmentEnum64 { _Align1Shl0 = 1 << 0, diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs index d34813599..7b1cb5488 100644 --- a/library/core/src/ptr/const_ptr.rs +++ b/library/core/src/ptr/const_ptr.rs @@ -1,6 +1,6 @@ use super::*; use crate::cmp::Ordering::{self, Equal, Greater, Less}; -use crate::intrinsics; +use crate::intrinsics::{self, const_eval_select}; use crate::mem; use crate::slice::{self, SliceIndex}; @@ -34,12 +34,23 @@ impl *const T { #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] #[inline] pub const fn is_null(self) -> bool { - // Compare via a cast to a thin pointer, so fat pointers are only - // considering their "data" part for null-ness. - match (self as *const u8).guaranteed_eq(null()) { - None => false, - Some(res) => res, + #[inline] + fn runtime_impl(ptr: *const u8) -> bool { + ptr.addr() == 0 } + + #[inline] + const fn const_impl(ptr: *const u8) -> bool { + // Compare via a cast to a thin pointer, so fat pointers are only + // considering their "data" part for null-ness. + match (ptr).guaranteed_eq(null_mut()) { + None => false, + Some(res) => res, + } + } + + // SAFETY: The two versions are equivalent at runtime. + unsafe { const_eval_select((self as *const u8,), const_impl, runtime_impl) } } /// Casts to a pointer of another type. @@ -191,14 +202,11 @@ impl *const T { #[must_use] #[inline(always)] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn addr(self) -> usize - where - T: Sized, - { + pub fn addr(self) -> usize { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. // SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the // provenance). - unsafe { mem::transmute(self) } + unsafe { mem::transmute(self.cast::<()>()) } } /// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future @@ -228,12 +236,9 @@ impl *const T { #[must_use] #[inline(always)] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn expose_addr(self) -> usize - where - T: Sized, - { + pub fn expose_addr(self) -> usize { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. - self as usize + self.cast::<()>() as usize } /// Creates a new pointer with the given address. @@ -251,10 +256,7 @@ impl *const T { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn with_addr(self, addr: usize) -> Self - where - T: Sized, - { + pub fn with_addr(self, addr: usize) -> Self { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. // // In the mean-time, this operation is defined to be "as if" it was @@ -277,10 +279,7 @@ impl *const T { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self - where - T: Sized, - { + pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self { self.with_addr(f(self.addr())) } @@ -1008,7 +1007,7 @@ impl *const T { #[stable(feature = "pointer_methods", since = "1.26.0")] #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")] - #[inline] + #[inline(always)] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub const unsafe fn sub(self, count: usize) -> Self where @@ -1173,7 +1172,7 @@ impl *const T { #[stable(feature = "pointer_methods", since = "1.26.0")] #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")] - #[inline] + #[inline(always)] pub const fn wrapping_sub(self, count: usize) -> Self where T: Sized, @@ -1350,26 +1349,6 @@ impl *const T { panic!("align_offset: align is not a power-of-two"); } - #[cfg(bootstrap)] - { - fn rt_impl(p: *const T, align: usize) -> usize { - // SAFETY: `align` has been checked to be a power of 2 above - unsafe { align_offset(p, align) } - } - - const fn ctfe_impl(_: *const T, _: usize) -> usize { - usize::MAX - } - - // SAFETY: - // It is permissible for `align_offset` to always return `usize::MAX`, - // algorithm correctness can not depend on `align_offset` returning non-max values. - // - // As such the behaviour can't change after replacing `align_offset` with `usize::MAX`, only performance can. - unsafe { intrinsics::const_eval_select((self, align), ctfe_impl, rt_impl) } - } - - #[cfg(not(bootstrap))] { // SAFETY: `align` has been checked to be a power of 2 above unsafe { align_offset(self, align) } @@ -1406,8 +1385,7 @@ impl *const T { /// is never aligned if cast to a type with a stricter alignment than the reference's /// underlying allocation. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1433,8 +1411,7 @@ impl *const T { /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime /// pointer is aligned, even if the compiletime pointer wasn't aligned. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1460,8 +1437,7 @@ impl *const T { /// If a pointer is created from a fixed address, this function behaves the same during /// runtime and compiletime. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1537,8 +1513,7 @@ impl *const T { /// return `true` if the pointer is guaranteed to be aligned. This means that the pointer /// cannot be stricter aligned than the reference's underlying allocation. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1563,8 +1538,7 @@ impl *const T { /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime /// pointer is aligned, even if the compiletime pointer wasn't aligned. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1588,8 +1562,7 @@ impl *const T { /// If a pointer is created from a fixed address, this function behaves the same during /// runtime and compiletime. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1613,11 +1586,22 @@ impl *const T { panic!("is_aligned_to: align is not a power-of-two"); } - // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead. - // The cast to `()` is used to - // 1. deal with fat pointers; and - // 2. ensure that `align_offset` doesn't actually try to compute an offset. - self.cast::<()>().align_offset(align) == 0 + #[inline] + fn runtime_impl(ptr: *const (), align: usize) -> bool { + ptr.addr() & (align - 1) == 0 + } + + #[inline] + const fn const_impl(ptr: *const (), align: usize) -> bool { + // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead. + // The cast to `()` is used to + // 1. deal with fat pointers; and + // 2. ensure that `align_offset` doesn't actually try to compute an offset. + ptr.align_offset(align) == 0 + } + + // SAFETY: The two versions are equivalent at runtime. + unsafe { const_eval_select((self.cast::<()>(), align), const_impl, runtime_impl) } } } diff --git a/library/core/src/ptr/metadata.rs b/library/core/src/ptr/metadata.rs index a8604843e..2ea032d4a 100644 --- a/library/core/src/ptr/metadata.rs +++ b/library/core/src/ptr/metadata.rs @@ -50,7 +50,7 @@ use crate::hash::{Hash, Hasher}; /// /// [`to_raw_parts`]: *const::to_raw_parts #[lang = "pointee_trait"] -#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)] +#[rustc_deny_explicit_impl] pub trait Pointee { /// The type for metadata in pointers and references to `Self`. #[lang = "metadata_type"] diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs index 48b2e88da..1ad9af154 100644 --- a/library/core/src/ptr/mod.rs +++ b/library/core/src/ptr/mod.rs @@ -516,6 +516,27 @@ pub const fn null() -> *const T { from_raw_parts(invalid(0), ()) } +/// Creates a null mutable raw pointer. +/// +/// # Examples +/// +/// ``` +/// use std::ptr; +/// +/// let p: *mut i32 = ptr::null_mut(); +/// assert!(p.is_null()); +/// ``` +#[inline(always)] +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +#[rustc_promotable] +#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")] +#[rustc_allow_const_fn_unstable(ptr_metadata)] +#[rustc_diagnostic_item = "ptr_null_mut"] +pub const fn null_mut() -> *mut T { + from_raw_parts_mut(invalid_mut(0), ()) +} + /// Creates an invalid pointer with the given address. /// /// This is different from `addr as *const T`, which creates a pointer that picks up a previously @@ -663,25 +684,26 @@ where addr as *mut T } -/// Creates a null mutable raw pointer. +/// Convert a reference to a raw pointer. /// -/// # Examples -/// -/// ``` -/// use std::ptr; +/// This is equivalent to `r as *const T`, but is a bit safer since it will never silently change +/// type or mutability, in particular if the code is refactored. +#[inline(always)] +#[must_use] +#[unstable(feature = "ptr_from_ref", issue = "106116")] +pub fn from_ref(r: &T) -> *const T { + r +} + +/// Convert a mutable reference to a raw pointer. /// -/// let p: *mut i32 = ptr::null_mut(); -/// assert!(p.is_null()); -/// ``` +/// This is equivalent to `r as *mut T`, but is a bit safer since it will never silently change +/// type or mutability, in particular if the code is refactored. #[inline(always)] #[must_use] -#[stable(feature = "rust1", since = "1.0.0")] -#[rustc_promotable] -#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")] -#[rustc_allow_const_fn_unstable(ptr_metadata)] -#[rustc_diagnostic_item = "ptr_null_mut"] -pub const fn null_mut() -> *mut T { - from_raw_parts_mut(invalid_mut(0), ()) +#[unstable(feature = "ptr_from_ref", issue = "106116")] +pub fn from_mut(r: &mut T) -> *mut T { + r } /// Forms a raw slice from a pointer and a length. @@ -1679,7 +1701,7 @@ pub(crate) const unsafe fn align_offset(p: *const T, a: usize) -> usiz // offset is not a multiple of `stride`, the input pointer was misaligned and no pointer // offset will be able to produce a `p` aligned to the specified `a`. // - // The naive `-p (mod a)` equation inhibits LLVM's ability to select instructions + // The naive `-p (mod a)` equation inhibits LLVM's ability to select instructions // like `lea`. We compute `(round_up_to_next_alignment(p, a) - p)` instead. This // redistributes operations around the load-bearing, but pessimizing `and` instruction // sufficiently for LLVM to be able to utilize the various optimizations it knows about. diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs index c924a90b1..ed1e3bd48 100644 --- a/library/core/src/ptr/mut_ptr.rs +++ b/library/core/src/ptr/mut_ptr.rs @@ -1,6 +1,6 @@ use super::*; use crate::cmp::Ordering::{self, Equal, Greater, Less}; -use crate::intrinsics; +use crate::intrinsics::{self, const_eval_select}; use crate::slice::{self, SliceIndex}; impl *mut T { @@ -33,12 +33,23 @@ impl *mut T { #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] #[inline] pub const fn is_null(self) -> bool { - // Compare via a cast to a thin pointer, so fat pointers are only - // considering their "data" part for null-ness. - match (self as *mut u8).guaranteed_eq(null_mut()) { - None => false, - Some(res) => res, + #[inline] + fn runtime_impl(ptr: *mut u8) -> bool { + ptr.addr() == 0 } + + #[inline] + const fn const_impl(ptr: *mut u8) -> bool { + // Compare via a cast to a thin pointer, so fat pointers are only + // considering their "data" part for null-ness. + match (ptr).guaranteed_eq(null_mut()) { + None => false, + Some(res) => res, + } + } + + // SAFETY: The two versions are equivalent at runtime. + unsafe { const_eval_select((self as *mut u8,), const_impl, runtime_impl) } } /// Casts to a pointer of another type. @@ -197,14 +208,11 @@ impl *mut T { #[must_use] #[inline(always)] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn addr(self) -> usize - where - T: Sized, - { + pub fn addr(self) -> usize { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. // SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the // provenance). - unsafe { mem::transmute(self) } + unsafe { mem::transmute(self.cast::<()>()) } } /// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future @@ -234,12 +242,9 @@ impl *mut T { #[must_use] #[inline(always)] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn expose_addr(self) -> usize - where - T: Sized, - { + pub fn expose_addr(self) -> usize { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. - self as usize + self.cast::<()>() as usize } /// Creates a new pointer with the given address. @@ -257,10 +262,7 @@ impl *mut T { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn with_addr(self, addr: usize) -> Self - where - T: Sized, - { + pub fn with_addr(self, addr: usize) -> Self { // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic. // // In the mean-time, this operation is defined to be "as if" it was @@ -283,10 +285,7 @@ impl *mut T { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self - where - T: Sized, - { + pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self { self.with_addr(f(self.addr())) } @@ -1110,7 +1109,7 @@ impl *mut T { #[stable(feature = "pointer_methods", since = "1.26.0")] #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")] - #[inline] + #[inline(always)] #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces pub const unsafe fn sub(self, count: usize) -> Self where @@ -1275,7 +1274,7 @@ impl *mut T { #[stable(feature = "pointer_methods", since = "1.26.0")] #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")] - #[inline] + #[inline(always)] pub const fn wrapping_sub(self, count: usize) -> Self where T: Sized, @@ -1618,26 +1617,6 @@ impl *mut T { panic!("align_offset: align is not a power-of-two"); } - #[cfg(bootstrap)] - { - fn rt_impl(p: *mut T, align: usize) -> usize { - // SAFETY: `align` has been checked to be a power of 2 above - unsafe { align_offset(p, align) } - } - - const fn ctfe_impl(_: *mut T, _: usize) -> usize { - usize::MAX - } - - // SAFETY: - // It is permissible for `align_offset` to always return `usize::MAX`, - // algorithm correctness can not depend on `align_offset` returning non-max values. - // - // As such the behaviour can't change after replacing `align_offset` with `usize::MAX`, only performance can. - unsafe { intrinsics::const_eval_select((self, align), ctfe_impl, rt_impl) } - } - - #[cfg(not(bootstrap))] { // SAFETY: `align` has been checked to be a power of 2 above unsafe { align_offset(self, align) } @@ -1674,8 +1653,7 @@ impl *mut T { /// is never aligned if cast to a type with a stricter alignment than the reference's /// underlying allocation. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// #![feature(const_mut_refs)] @@ -1702,8 +1680,7 @@ impl *mut T { /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime /// pointer is aligned, even if the compiletime pointer wasn't aligned. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1730,8 +1707,7 @@ impl *mut T { /// If a pointer is created from a fixed address, this function behaves the same during /// runtime and compiletime. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1807,8 +1783,7 @@ impl *mut T { /// return `true` if the pointer is guaranteed to be aligned. This means that the pointer /// cannot be stricter aligned than the reference's underlying allocation. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// #![feature(const_mut_refs)] @@ -1834,8 +1809,7 @@ impl *mut T { /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime /// pointer is aligned, even if the compiletime pointer wasn't aligned. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1860,8 +1834,7 @@ impl *mut T { /// If a pointer is created from a fixed address, this function behaves the same during /// runtime and compiletime. /// - #[cfg_attr(bootstrap, doc = "```ignore")] - #[cfg_attr(not(bootstrap), doc = "```")] + /// ``` /// #![feature(pointer_is_aligned)] /// #![feature(const_pointer_is_aligned)] /// @@ -1885,11 +1858,22 @@ impl *mut T { panic!("is_aligned_to: align is not a power-of-two"); } - // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead. - // The cast to `()` is used to - // 1. deal with fat pointers; and - // 2. ensure that `align_offset` doesn't actually try to compute an offset. - self.cast::<()>().align_offset(align) == 0 + #[inline] + fn runtime_impl(ptr: *mut (), align: usize) -> bool { + ptr.addr() & (align - 1) == 0 + } + + #[inline] + const fn const_impl(ptr: *mut (), align: usize) -> bool { + // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead. + // The cast to `()` is used to + // 1. deal with fat pointers; and + // 2. ensure that `align_offset` doesn't actually try to compute an offset. + ptr.align_offset(align) == 0 + } + + // SAFETY: The two versions are equivalent at runtime. + unsafe { const_eval_select((self.cast::<()>(), align), const_impl, runtime_impl) } } } diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs index c4348169c..8c1a64886 100644 --- a/library/core/src/ptr/non_null.rs +++ b/library/core/src/ptr/non_null.rs @@ -268,10 +268,7 @@ impl NonNull { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn addr(self) -> NonZeroUsize - where - T: Sized, - { + pub fn addr(self) -> NonZeroUsize { // SAFETY: The pointer is guaranteed by the type to be non-null, // meaning that the address will be non-zero. unsafe { NonZeroUsize::new_unchecked(self.pointer.addr()) } @@ -286,10 +283,7 @@ impl NonNull { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn with_addr(self, addr: NonZeroUsize) -> Self - where - T: Sized, - { + pub fn with_addr(self, addr: NonZeroUsize) -> Self { // SAFETY: The result of `ptr::from::with_addr` is non-null because `addr` is guaranteed to be non-zero. unsafe { NonNull::new_unchecked(self.pointer.with_addr(addr.get()) as *mut _) } } @@ -303,10 +297,7 @@ impl NonNull { #[must_use] #[inline] #[unstable(feature = "strict_provenance", issue = "95228")] - pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self - where - T: Sized, - { + pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self { self.with_addr(f(self.addr())) } @@ -712,7 +703,7 @@ impl const Clone for NonNull { #[stable(feature = "nonnull", since = "1.25.0")] impl Copy for NonNull {} -#[unstable(feature = "coerce_unsized", issue = "27732")] +#[unstable(feature = "coerce_unsized", issue = "18598")] impl CoerceUnsized> for NonNull where T: Unsize {} #[unstable(feature = "dispatch_from_dyn", issue = "none")] diff --git a/library/core/src/result.rs b/library/core/src/result.rs index 3f33c5fd6..f00c40f35 100644 --- a/library/core/src/result.rs +++ b/library/core/src/result.rs @@ -209,11 +209,10 @@ //! //! *It's much nicer!* //! -//! Ending the expression with [`?`] will result in the unwrapped -//! success ([`Ok`]) value, unless the result is [`Err`], in which case -//! [`Err`] is returned early from the enclosing function. +//! Ending the expression with [`?`] will result in the [`Ok`]'s unwrapped value, unless the result +//! is [`Err`], in which case [`Err`] is returned early from the enclosing function. //! -//! [`?`] can only be used in functions that return [`Result`] because of the +//! [`?`] can be used in functions that return [`Result`] because of the //! early return of [`Err`] that it provides. //! //! [`expect`]: Result::expect diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs index 062289767..90ab43d12 100644 --- a/library/core/src/slice/iter.rs +++ b/library/core/src/slice/iter.rs @@ -6,7 +6,7 @@ mod macros; use crate::cmp; use crate::cmp::Ordering; use crate::fmt; -use crate::intrinsics::{assume, exact_div, unchecked_sub}; +use crate::intrinsics::assume; use crate::iter::{FusedIterator, TrustedLen, TrustedRandomAccess, TrustedRandomAccessNoCoerce}; use crate::marker::{PhantomData, Send, Sized, Sync}; use crate::mem::{self, SizedTypeProperties}; @@ -35,12 +35,6 @@ impl<'a, T> IntoIterator for &'a mut [T] { } } -// Macro helper functions -#[inline(always)] -fn size_from_ptr(_: *const T) -> usize { - mem::size_of::() -} - /// Immutable slice iterator /// /// This struct is created by the [`iter`] method on [slices]. @@ -65,7 +59,7 @@ fn size_from_ptr(_: *const T) -> usize { #[must_use = "iterators are lazy and do nothing unless consumed"] pub struct Iter<'a, T: 'a> { ptr: NonNull, - end: *const T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that + end: *const T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that // ptr == end is a quick test for the Iterator being empty, that works // for both ZST and non-ZST. _marker: PhantomData<&'a T>, @@ -186,7 +180,7 @@ impl AsRef<[T]> for Iter<'_, T> { #[must_use = "iterators are lazy and do nothing unless consumed"] pub struct IterMut<'a, T: 'a> { ptr: NonNull, - end: *mut T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that + end: *mut T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that // ptr == end is a quick test for the Iterator being empty, that works // for both ZST and non-ZST. _marker: PhantomData<&'a mut T>, diff --git a/library/core/src/slice/iter/macros.rs b/library/core/src/slice/iter/macros.rs index ce51d48e3..0fd57b197 100644 --- a/library/core/src/slice/iter/macros.rs +++ b/library/core/src/slice/iter/macros.rs @@ -9,30 +9,20 @@ macro_rules! is_empty { }; } -// To get rid of some bounds checks (see `position`), we compute the length in a somewhat -// unexpected way. (Tested by `codegen/slice-position-bounds-check`.) macro_rules! len { ($self: ident) => {{ #![allow(unused_unsafe)] // we're sometimes used within an unsafe block let start = $self.ptr; - let size = size_from_ptr(start.as_ptr()); - if size == 0 { - // This _cannot_ use `unchecked_sub` because we depend on wrapping + if T::IS_ZST { + // This _cannot_ use `ptr_sub` because we depend on wrapping // to represent the length of long ZST slice iterators. $self.end.addr().wrapping_sub(start.as_ptr().addr()) } else { - // We know that `start <= end`, so can do better than `offset_from`, - // which needs to deal in signed. By setting appropriate flags here - // we can tell LLVM this, which helps it remove bounds checks. - // SAFETY: By the type invariant, `start <= end` - let diff = unsafe { unchecked_sub($self.end.addr(), start.as_ptr().addr()) }; - // By also telling LLVM that the pointers are apart by an exact - // multiple of the type size, it can optimize `len() == 0` down to - // `start == end` instead of `(end - start) < size`. - // SAFETY: By the type invariant, the pointers are aligned so the - // distance between them must be a multiple of pointee size - unsafe { exact_div(diff, size) } + // To get rid of some bounds checks (see `position`), we use ptr_sub instead of + // offset_from (Tested by `codegen/slice-position-bounds-check`.) + // SAFETY: by the type invariant pointers are aligned and `start <= end` + unsafe { $self.end.sub_ptr(start.as_ptr()) } } }}; } diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs index d9281a925..d93a3a57e 100644 --- a/library/core/src/slice/mod.rs +++ b/library/core/src/slice/mod.rs @@ -29,13 +29,19 @@ use crate::slice; /// Pure rust memchr implementation, taken from rust-memchr pub mod memchr; +#[unstable( + feature = "slice_internals", + issue = "none", + reason = "exposed from core to be reused in std;" +)] +pub mod sort; + mod ascii; mod cmp; mod index; mod iter; mod raw; mod rotate; -mod sort; mod specialize; #[stable(feature = "rust1", since = "1.0.0")] @@ -703,7 +709,7 @@ impl [T] { // Because this function is first compiled in isolation, // this check tells LLVM that the indexing below is - // in-bounds. Then after inlining -- once the actual + // in-bounds. Then after inlining -- once the actual // lengths of the slices are known -- it's removed. let (a, b) = (&mut a[..n], &mut b[..n]); @@ -781,6 +787,22 @@ impl [T] { /// let mut iter = slice.windows(4); /// assert!(iter.next().is_none()); /// ``` + /// + /// There's no `windows_mut`, as that existing would let safe code violate the + /// "only one `&mut` at a time to the same thing" rule. However, you can sometimes + /// use [`Cell::as_slice_of_cells`](crate::cell::Cell::as_slice_of_cells) in + /// conjunction with `windows` to accomplish something similar: + /// ``` + /// use std::cell::Cell; + /// + /// let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5']; + /// let slice = &mut array[..]; + /// let slice_of_cells: &[Cell] = Cell::from_mut(slice).as_slice_of_cells(); + /// for w in slice_of_cells.windows(3) { + /// Cell::swap(&w[0], &w[2]); + /// } + /// assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn windows(&self, size: usize) -> Windows<'_, T> { @@ -893,7 +915,7 @@ impl [T] { #[stable(feature = "chunks_exact", since = "1.31.0")] #[inline] pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> { - assert_ne!(chunk_size, 0); + assert_ne!(chunk_size, 0, "chunks cannot have a size of zero"); ChunksExact::new(self, chunk_size) } @@ -935,7 +957,7 @@ impl [T] { #[stable(feature = "chunks_exact", since = "1.31.0")] #[inline] pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> { - assert_ne!(chunk_size, 0); + assert_ne!(chunk_size, 0, "chunks cannot have a size of zero"); ChunksExactMut::new(self, chunk_size) } @@ -1002,11 +1024,22 @@ impl [T] { /// assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]); /// assert_eq!(remainder, &['m']); /// ``` + /// + /// If you expect the slice to be an exact multiple, you can combine + /// `let`-`else` with an empty slice pattern: + /// ``` + /// #![feature(slice_as_chunks)] + /// let slice = ['R', 'u', 's', 't']; + /// let (chunks, []) = slice.as_chunks::<2>() else { + /// panic!("slice didn't have even length") + /// }; + /// assert_eq!(chunks, &[['R', 'u'], ['s', 't']]); + /// ``` #[unstable(feature = "slice_as_chunks", issue = "74985")] #[inline] #[must_use] pub fn as_chunks(&self) -> (&[[T; N]], &[T]) { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); let len = self.len() / N; let (multiple_of_n, remainder) = self.split_at(len * N); // SAFETY: We already panicked for zero, and ensured by construction @@ -1037,7 +1070,7 @@ impl [T] { #[inline] #[must_use] pub fn as_rchunks(&self) -> (&[T], &[[T; N]]) { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); let len = self.len() / N; let (remainder, multiple_of_n) = self.split_at(self.len() - len * N); // SAFETY: We already panicked for zero, and ensured by construction @@ -1076,7 +1109,7 @@ impl [T] { #[unstable(feature = "array_chunks", issue = "74985")] #[inline] pub fn array_chunks(&self) -> ArrayChunks<'_, T, N> { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); ArrayChunks::new(self) } @@ -1155,7 +1188,7 @@ impl [T] { #[inline] #[must_use] pub fn as_chunks_mut(&mut self) -> (&mut [[T; N]], &mut [T]) { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); let len = self.len() / N; let (multiple_of_n, remainder) = self.split_at_mut(len * N); // SAFETY: We already panicked for zero, and ensured by construction @@ -1192,7 +1225,7 @@ impl [T] { #[inline] #[must_use] pub fn as_rchunks_mut(&mut self) -> (&mut [T], &mut [[T; N]]) { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); let len = self.len() / N; let (remainder, multiple_of_n) = self.split_at_mut(self.len() - len * N); // SAFETY: We already panicked for zero, and ensured by construction @@ -1233,11 +1266,11 @@ impl [T] { #[unstable(feature = "array_chunks", issue = "74985")] #[inline] pub fn array_chunks_mut(&mut self) -> ArrayChunksMut<'_, T, N> { - assert_ne!(N, 0); + assert_ne!(N, 0, "chunks cannot have a size of zero"); ArrayChunksMut::new(self) } - /// Returns an iterator over overlapping windows of `N` elements of a slice, + /// Returns an iterator over overlapping windows of `N` elements of a slice, /// starting at the beginning of the slice. /// /// This is the const generic equivalent of [`windows`]. @@ -1265,7 +1298,7 @@ impl [T] { #[unstable(feature = "array_windows", issue = "75027")] #[inline] pub fn array_windows(&self) -> ArrayWindows<'_, T, N> { - assert_ne!(N, 0); + assert_ne!(N, 0, "windows cannot have a size of zero"); ArrayWindows::new(self) } @@ -2465,7 +2498,7 @@ impl [T] { let mid = left + size / 2; // SAFETY: the while condition means `size` is strictly positive, so - // `size/2 < size`. Thus `left + size/2 < left + size`, which + // `size/2 < size`. Thus `left + size/2 < left + size`, which // coupled with the `left + size <= self.len()` invariant means // we have `left + size/2 < self.len()`, and this is in-bounds. let cmp = f(unsafe { self.get_unchecked(mid) }); @@ -3795,7 +3828,7 @@ impl [T] { /// The slice is assumed to be partitioned according to the given predicate. /// This means that all elements for which the predicate returns true are at the start of the slice /// and all elements for which the predicate returns false are at the end. - /// For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0 + /// For example, `[7, 15, 3, 5, 4, 12, 6]` is partitioned under the predicate `x % 2 != 0` /// (all odd numbers are at the start, all even at the end). /// /// If this slice is not partitioned, the returned result is unspecified and meaningless, diff --git a/library/core/src/slice/sort.rs b/library/core/src/slice/sort.rs index 87f77b7f2..2181f9a81 100644 --- a/library/core/src/slice/sort.rs +++ b/library/core/src/slice/sort.rs @@ -3,8 +3,11 @@ //! This module contains a sorting algorithm based on Orson Peters' pattern-defeating quicksort, //! published at: //! -//! Unstable sorting is compatible with libcore because it doesn't allocate memory, unlike our +//! Unstable sorting is compatible with core because it doesn't allocate memory, unlike our //! stable sorting implementation. +//! +//! In addition it also contains the core logic of the stable sort used by `slice::sort` based on +//! TimSort. use crate::cmp; use crate::mem::{self, MaybeUninit, SizedTypeProperties}; @@ -18,9 +21,9 @@ struct CopyOnDrop { impl Drop for CopyOnDrop { fn drop(&mut self) { - // SAFETY: This is a helper class. - // Please refer to its usage for correctness. - // Namely, one must be sure that `src` and `dst` does not overlap as required by `ptr::copy_nonoverlapping`. + // SAFETY: This is a helper class. + // Please refer to its usage for correctness. + // Namely, one must be sure that `src` and `dst` does not overlap as required by `ptr::copy_nonoverlapping`. unsafe { ptr::copy_nonoverlapping(self.src, self.dest, 1); } @@ -831,6 +834,15 @@ fn partition_at_index_loop<'a, T, F>( ) where F: FnMut(&T, &T) -> bool, { + // Limit the amount of iterations and fall back to heapsort, similarly to `slice::sort_unstable`. + // This lowers the worst case running time from O(n^2) to O(n log n). + // FIXME: Investigate whether it would be better to use something like Median of Medians + // or Fast Deterministic Selection to guarantee O(n) worst case. + let mut limit = usize::BITS - v.len().leading_zeros(); + + // True if the last partitioning was reasonably balanced. + let mut was_balanced = true; + loop { // For slices of up to this length it's probably faster to simply sort them. const MAX_INSERTION: usize = 10; @@ -839,6 +851,18 @@ fn partition_at_index_loop<'a, T, F>( return; } + if limit == 0 { + heapsort(v, is_less); + return; + } + + // If the last partitioning was imbalanced, try breaking patterns in the slice by shuffling + // some elements around. Hopefully we'll choose a better pivot this time. + if !was_balanced { + break_patterns(v); + limit -= 1; + } + // Choose a pivot let (pivot, _) = choose_pivot(v, is_less); @@ -863,6 +887,7 @@ fn partition_at_index_loop<'a, T, F>( } let (mid, _) = partition(v, pivot, is_less); + was_balanced = cmp::min(mid, v.len() - mid) >= v.len() / 8; // Split the slice into `left`, `pivot`, and `right`. let (left, right) = v.split_at_mut(mid); @@ -883,6 +908,7 @@ fn partition_at_index_loop<'a, T, F>( } } +/// Reorder the slice such that the element at `index` is at its final sorted position. pub fn partition_at_index( v: &mut [T], index: usize, @@ -927,3 +953,513 @@ where let pivot = &mut pivot[0]; (left, pivot, right) } + +/// Inserts `v[0]` into pre-sorted sequence `v[1..]` so that whole `v[..]` becomes sorted. +/// +/// This is the integral subroutine of insertion sort. +fn insert_head(v: &mut [T], is_less: &mut F) +where + F: FnMut(&T, &T) -> bool, +{ + if v.len() >= 2 && is_less(&v[1], &v[0]) { + // SAFETY: Copy tmp back even if panic, and ensure unique observation. + unsafe { + // There are three ways to implement insertion here: + // + // 1. Swap adjacent elements until the first one gets to its final destination. + // However, this way we copy data around more than is necessary. If elements are big + // structures (costly to copy), this method will be slow. + // + // 2. Iterate until the right place for the first element is found. Then shift the + // elements succeeding it to make room for it and finally place it into the + // remaining hole. This is a good method. + // + // 3. Copy the first element into a temporary variable. Iterate until the right place + // for it is found. As we go along, copy every traversed element into the slot + // preceding it. Finally, copy data from the temporary variable into the remaining + // hole. This method is very good. Benchmarks demonstrated slightly better + // performance than with the 2nd method. + // + // All methods were benchmarked, and the 3rd showed best results. So we chose that one. + let tmp = mem::ManuallyDrop::new(ptr::read(&v[0])); + + // Intermediate state of the insertion process is always tracked by `hole`, which + // serves two purposes: + // 1. Protects integrity of `v` from panics in `is_less`. + // 2. Fills the remaining hole in `v` in the end. + // + // Panic safety: + // + // If `is_less` panics at any point during the process, `hole` will get dropped and + // fill the hole in `v` with `tmp`, thus ensuring that `v` still holds every object it + // initially held exactly once. + let mut hole = InsertionHole { src: &*tmp, dest: &mut v[1] }; + ptr::copy_nonoverlapping(&v[1], &mut v[0], 1); + + for i in 2..v.len() { + if !is_less(&v[i], &*tmp) { + break; + } + ptr::copy_nonoverlapping(&v[i], &mut v[i - 1], 1); + hole.dest = &mut v[i]; + } + // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`. + } + } + + // When dropped, copies from `src` into `dest`. + struct InsertionHole { + src: *const T, + dest: *mut T, + } + + impl Drop for InsertionHole { + fn drop(&mut self) { + // SAFETY: The caller must ensure that src and dest are correctly set. + unsafe { + ptr::copy_nonoverlapping(self.src, self.dest, 1); + } + } + } +} + +/// Merges non-decreasing runs `v[..mid]` and `v[mid..]` using `buf` as temporary storage, and +/// stores the result into `v[..]`. +/// +/// # Safety +/// +/// The two slices must be non-empty and `mid` must be in bounds. Buffer `buf` must be long enough +/// to hold a copy of the shorter slice. Also, `T` must not be a zero-sized type. +unsafe fn merge(v: &mut [T], mid: usize, buf: *mut T, is_less: &mut F) +where + F: FnMut(&T, &T) -> bool, +{ + let len = v.len(); + let v = v.as_mut_ptr(); + + // SAFETY: mid and len must be in-bounds of v. + let (v_mid, v_end) = unsafe { (v.add(mid), v.add(len)) }; + + // The merge process first copies the shorter run into `buf`. Then it traces the newly copied + // run and the longer run forwards (or backwards), comparing their next unconsumed elements and + // copying the lesser (or greater) one into `v`. + // + // As soon as the shorter run is fully consumed, the process is done. If the longer run gets + // consumed first, then we must copy whatever is left of the shorter run into the remaining + // hole in `v`. + // + // Intermediate state of the process is always tracked by `hole`, which serves two purposes: + // 1. Protects integrity of `v` from panics in `is_less`. + // 2. Fills the remaining hole in `v` if the longer run gets consumed first. + // + // Panic safety: + // + // If `is_less` panics at any point during the process, `hole` will get dropped and fill the + // hole in `v` with the unconsumed range in `buf`, thus ensuring that `v` still holds every + // object it initially held exactly once. + let mut hole; + + if mid <= len - mid { + // The left run is shorter. + + // SAFETY: buf must have enough capacity for `v[..mid]`. + unsafe { + ptr::copy_nonoverlapping(v, buf, mid); + hole = MergeHole { start: buf, end: buf.add(mid), dest: v }; + } + + // Initially, these pointers point to the beginnings of their arrays. + let left = &mut hole.start; + let mut right = v_mid; + let out = &mut hole.dest; + + while *left < hole.end && right < v_end { + // Consume the lesser side. + // If equal, prefer the left run to maintain stability. + + // SAFETY: left and right must be valid and part of v same for out. + unsafe { + let to_copy = if is_less(&*right, &**left) { + get_and_increment(&mut right) + } else { + get_and_increment(left) + }; + ptr::copy_nonoverlapping(to_copy, get_and_increment(out), 1); + } + } + } else { + // The right run is shorter. + + // SAFETY: buf must have enough capacity for `v[mid..]`. + unsafe { + ptr::copy_nonoverlapping(v_mid, buf, len - mid); + hole = MergeHole { start: buf, end: buf.add(len - mid), dest: v_mid }; + } + + // Initially, these pointers point past the ends of their arrays. + let left = &mut hole.dest; + let right = &mut hole.end; + let mut out = v_end; + + while v < *left && buf < *right { + // Consume the greater side. + // If equal, prefer the right run to maintain stability. + + // SAFETY: left and right must be valid and part of v same for out. + unsafe { + let to_copy = if is_less(&*right.sub(1), &*left.sub(1)) { + decrement_and_get(left) + } else { + decrement_and_get(right) + }; + ptr::copy_nonoverlapping(to_copy, decrement_and_get(&mut out), 1); + } + } + } + // Finally, `hole` gets dropped. If the shorter run was not fully consumed, whatever remains of + // it will now be copied into the hole in `v`. + + unsafe fn get_and_increment(ptr: &mut *mut T) -> *mut T { + let old = *ptr; + + // SAFETY: ptr.add(1) must still be a valid pointer and part of `v`. + *ptr = unsafe { ptr.add(1) }; + old + } + + unsafe fn decrement_and_get(ptr: &mut *mut T) -> *mut T { + // SAFETY: ptr.sub(1) must still be a valid pointer and part of `v`. + *ptr = unsafe { ptr.sub(1) }; + *ptr + } + + // When dropped, copies the range `start..end` into `dest..`. + struct MergeHole { + start: *mut T, + end: *mut T, + dest: *mut T, + } + + impl Drop for MergeHole { + fn drop(&mut self) { + // SAFETY: `T` is not a zero-sized type, and these are pointers into a slice's elements. + unsafe { + let len = self.end.sub_ptr(self.start); + ptr::copy_nonoverlapping(self.start, self.dest, len); + } + } + } +} + +/// This merge sort borrows some (but not all) ideas from TimSort, which used to be described in +/// detail [here](https://github.com/python/cpython/blob/main/Objects/listsort.txt). However Python +/// has switched to a Powersort based implementation. +/// +/// The algorithm identifies strictly descending and non-descending subsequences, which are called +/// natural runs. There is a stack of pending runs yet to be merged. Each newly found run is pushed +/// onto the stack, and then some pairs of adjacent runs are merged until these two invariants are +/// satisfied: +/// +/// 1. for every `i` in `1..runs.len()`: `runs[i - 1].len > runs[i].len` +/// 2. for every `i` in `2..runs.len()`: `runs[i - 2].len > runs[i - 1].len + runs[i].len` +/// +/// The invariants ensure that the total running time is *O*(*n* \* log(*n*)) worst-case. +pub fn merge_sort( + v: &mut [T], + is_less: &mut CmpF, + elem_alloc_fn: ElemAllocF, + elem_dealloc_fn: ElemDeallocF, + run_alloc_fn: RunAllocF, + run_dealloc_fn: RunDeallocF, +) where + CmpF: FnMut(&T, &T) -> bool, + ElemAllocF: Fn(usize) -> *mut T, + ElemDeallocF: Fn(*mut T, usize), + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), +{ + // Slices of up to this length get sorted using insertion sort. + const MAX_INSERTION: usize = 20; + // Very short runs are extended using insertion sort to span at least this many elements. + const MIN_RUN: usize = 10; + + // The caller should have already checked that. + debug_assert!(!T::IS_ZST); + + let len = v.len(); + + // Short arrays get sorted in-place via insertion sort to avoid allocations. + if len <= MAX_INSERTION { + if len >= 2 { + for i in (0..len - 1).rev() { + insert_head(&mut v[i..], is_less); + } + } + return; + } + + // Allocate a buffer to use as scratch memory. We keep the length 0 so we can keep in it + // shallow copies of the contents of `v` without risking the dtors running on copies if + // `is_less` panics. When merging two sorted runs, this buffer holds a copy of the shorter run, + // which will always have length at most `len / 2`. + let buf = BufGuard::new(len / 2, elem_alloc_fn, elem_dealloc_fn); + let buf_ptr = buf.buf_ptr; + + let mut runs = RunVec::new(run_alloc_fn, run_dealloc_fn); + + // In order to identify natural runs in `v`, we traverse it backwards. That might seem like a + // strange decision, but consider the fact that merges more often go in the opposite direction + // (forwards). According to benchmarks, merging forwards is slightly faster than merging + // backwards. To conclude, identifying runs by traversing backwards improves performance. + let mut end = len; + while end > 0 { + // Find the next natural run, and reverse it if it's strictly descending. + let mut start = end - 1; + if start > 0 { + start -= 1; + + // SAFETY: The v.get_unchecked must be fed with correct inbound indicies. + unsafe { + if is_less(v.get_unchecked(start + 1), v.get_unchecked(start)) { + while start > 0 && is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) { + start -= 1; + } + v[start..end].reverse(); + } else { + while start > 0 && !is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) + { + start -= 1; + } + } + } + } + + // Insert some more elements into the run if it's too short. Insertion sort is faster than + // merge sort on short sequences, so this significantly improves performance. + while start > 0 && end - start < MIN_RUN { + start -= 1; + insert_head(&mut v[start..end], is_less); + } + + // Push this run onto the stack. + runs.push(TimSortRun { start, len: end - start }); + end = start; + + // Merge some pairs of adjacent runs to satisfy the invariants. + while let Some(r) = collapse(runs.as_slice()) { + let left = runs[r + 1]; + let right = runs[r]; + // SAFETY: `buf_ptr` must hold enough capacity for the shorter of the two sides, and + // neither side may be on length 0. + unsafe { + merge(&mut v[left.start..right.start + right.len], left.len, buf_ptr, is_less); + } + runs[r] = TimSortRun { start: left.start, len: left.len + right.len }; + runs.remove(r + 1); + } + } + + // Finally, exactly one run must remain in the stack. + debug_assert!(runs.len() == 1 && runs[0].start == 0 && runs[0].len == len); + + // Examines the stack of runs and identifies the next pair of runs to merge. More specifically, + // if `Some(r)` is returned, that means `runs[r]` and `runs[r + 1]` must be merged next. If the + // algorithm should continue building a new run instead, `None` is returned. + // + // TimSort is infamous for its buggy implementations, as described here: + // http://envisage-project.eu/timsort-specification-and-verification/ + // + // The gist of the story is: we must enforce the invariants on the top four runs on the stack. + // Enforcing them on just top three is not sufficient to ensure that the invariants will still + // hold for *all* runs in the stack. + // + // This function correctly checks invariants for the top four runs. Additionally, if the top + // run starts at index 0, it will always demand a merge operation until the stack is fully + // collapsed, in order to complete the sort. + #[inline] + fn collapse(runs: &[TimSortRun]) -> Option { + let n = runs.len(); + if n >= 2 + && (runs[n - 1].start == 0 + || runs[n - 2].len <= runs[n - 1].len + || (n >= 3 && runs[n - 3].len <= runs[n - 2].len + runs[n - 1].len) + || (n >= 4 && runs[n - 4].len <= runs[n - 3].len + runs[n - 2].len)) + { + if n >= 3 && runs[n - 3].len < runs[n - 1].len { Some(n - 3) } else { Some(n - 2) } + } else { + None + } + } + + // Extremely basic versions of Vec. + // Their use is super limited and by having the code here, it allows reuse between the sort + // implementations. + struct BufGuard + where + ElemDeallocF: Fn(*mut T, usize), + { + buf_ptr: *mut T, + capacity: usize, + elem_dealloc_fn: ElemDeallocF, + } + + impl BufGuard + where + ElemDeallocF: Fn(*mut T, usize), + { + fn new( + len: usize, + elem_alloc_fn: ElemAllocF, + elem_dealloc_fn: ElemDeallocF, + ) -> Self + where + ElemAllocF: Fn(usize) -> *mut T, + { + Self { buf_ptr: elem_alloc_fn(len), capacity: len, elem_dealloc_fn } + } + } + + impl Drop for BufGuard + where + ElemDeallocF: Fn(*mut T, usize), + { + fn drop(&mut self) { + (self.elem_dealloc_fn)(self.buf_ptr, self.capacity); + } + } + + struct RunVec + where + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), + { + buf_ptr: *mut TimSortRun, + capacity: usize, + len: usize, + run_alloc_fn: RunAllocF, + run_dealloc_fn: RunDeallocF, + } + + impl RunVec + where + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), + { + fn new(run_alloc_fn: RunAllocF, run_dealloc_fn: RunDeallocF) -> Self { + // Most slices can be sorted with at most 16 runs in-flight. + const START_RUN_CAPACITY: usize = 16; + + Self { + buf_ptr: run_alloc_fn(START_RUN_CAPACITY), + capacity: START_RUN_CAPACITY, + len: 0, + run_alloc_fn, + run_dealloc_fn, + } + } + + fn push(&mut self, val: TimSortRun) { + if self.len == self.capacity { + let old_capacity = self.capacity; + let old_buf_ptr = self.buf_ptr; + + self.capacity = self.capacity * 2; + self.buf_ptr = (self.run_alloc_fn)(self.capacity); + + // SAFETY: buf_ptr new and old were correctly allocated and old_buf_ptr has + // old_capacity valid elements. + unsafe { + ptr::copy_nonoverlapping(old_buf_ptr, self.buf_ptr, old_capacity); + } + + (self.run_dealloc_fn)(old_buf_ptr, old_capacity); + } + + // SAFETY: The invariant was just checked. + unsafe { + self.buf_ptr.add(self.len).write(val); + } + self.len += 1; + } + + fn remove(&mut self, index: usize) { + if index >= self.len { + panic!("Index out of bounds"); + } + + // SAFETY: buf_ptr needs to be valid and len invariant upheld. + unsafe { + // the place we are taking from. + let ptr = self.buf_ptr.add(index); + + // Shift everything down to fill in that spot. + ptr::copy(ptr.add(1), ptr, self.len - index - 1); + } + self.len -= 1; + } + + fn as_slice(&self) -> &[TimSortRun] { + // SAFETY: Safe as long as buf_ptr is valid and len invariant was upheld. + unsafe { &*ptr::slice_from_raw_parts(self.buf_ptr, self.len) } + } + + fn len(&self) -> usize { + self.len + } + } + + impl core::ops::Index for RunVec + where + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), + { + type Output = TimSortRun; + + fn index(&self, index: usize) -> &Self::Output { + if index < self.len { + // SAFETY: buf_ptr and len invariant must be upheld. + unsafe { + return &*(self.buf_ptr.add(index)); + } + } + + panic!("Index out of bounds"); + } + } + + impl core::ops::IndexMut for RunVec + where + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), + { + fn index_mut(&mut self, index: usize) -> &mut Self::Output { + if index < self.len { + // SAFETY: buf_ptr and len invariant must be upheld. + unsafe { + return &mut *(self.buf_ptr.add(index)); + } + } + + panic!("Index out of bounds"); + } + } + + impl Drop for RunVec + where + RunAllocF: Fn(usize) -> *mut TimSortRun, + RunDeallocF: Fn(*mut TimSortRun, usize), + { + fn drop(&mut self) { + // As long as TimSortRun is Copy we don't need to drop them individually but just the + // whole allocation. + (self.run_dealloc_fn)(self.buf_ptr, self.capacity); + } + } +} + +/// Internal type used by merge_sort. +#[derive(Clone, Copy, Debug)] +pub struct TimSortRun { + len: usize, + start: usize, +} diff --git a/library/core/src/str/iter.rs b/library/core/src/str/iter.rs index 24083ee6a..d969475aa 100644 --- a/library/core/src/str/iter.rs +++ b/library/core/src/str/iter.rs @@ -585,16 +585,17 @@ where impl<'a, P: Pattern<'a>> SplitInternal<'a, P> { #[inline] fn get_end(&mut self) -> Option<&'a str> { - if !self.finished && (self.allow_trailing_empty || self.end - self.start > 0) { + if !self.finished { self.finished = true; - // SAFETY: `self.start` and `self.end` always lie on unicode boundaries. - unsafe { - let string = self.matcher.haystack().get_unchecked(self.start..self.end); - Some(string) + + if self.allow_trailing_empty || self.end - self.start > 0 { + // SAFETY: `self.start` and `self.end` always lie on unicode boundaries. + let string = unsafe { self.matcher.haystack().get_unchecked(self.start..self.end) }; + return Some(string); } - } else { - None } + + None } #[inline] @@ -716,14 +717,14 @@ impl<'a, P: Pattern<'a>> SplitInternal<'a, P> { } #[inline] - fn as_str(&self) -> &'a str { + fn remainder(&self) -> Option<&'a str> { // `Self::get_end` doesn't change `self.start` if self.finished { - return ""; + return None; } // SAFETY: `self.start` and `self.end` always lie on unicode boundaries. - unsafe { self.matcher.haystack().get_unchecked(self.start..self.end) } + Some(unsafe { self.matcher.haystack().get_unchecked(self.start..self.end) }) } } @@ -746,44 +747,48 @@ generate_pattern_iterators! { } impl<'a, P: Pattern<'a>> Split<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "Mary had a little lamb".split(' '); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// split.next(); - /// assert_eq!(split.as_str(), "had a little lamb"); + /// assert_eq!(split.remainder(), Some("had a little lamb")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } impl<'a, P: Pattern<'a>> RSplit<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "Mary had a little lamb".rsplit(' '); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// split.next(); - /// assert_eq!(split.as_str(), "Mary had a little"); + /// assert_eq!(split.remainder(), Some("Mary had a little")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } @@ -806,44 +811,48 @@ generate_pattern_iterators! { } impl<'a, P: Pattern<'a>> SplitTerminator<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "A..B..".split_terminator('.'); - /// assert_eq!(split.as_str(), "A..B.."); + /// assert_eq!(split.remainder(), Some("A..B..")); /// split.next(); - /// assert_eq!(split.as_str(), ".B.."); + /// assert_eq!(split.remainder(), Some(".B..")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } impl<'a, P: Pattern<'a>> RSplitTerminator<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "A..B..".rsplit_terminator('.'); - /// assert_eq!(split.as_str(), "A..B.."); + /// assert_eq!(split.remainder(), Some("A..B..")); /// split.next(); - /// assert_eq!(split.as_str(), "A..B"); + /// assert_eq!(split.remainder(), Some("A..B")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } @@ -905,8 +914,8 @@ impl<'a, P: Pattern<'a>> SplitNInternal<'a, P> { } #[inline] - fn as_str(&self) -> &'a str { - self.iter.as_str() + fn remainder(&self) -> Option<&'a str> { + self.iter.remainder() } } @@ -929,44 +938,48 @@ generate_pattern_iterators! { } impl<'a, P: Pattern<'a>> SplitN<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "Mary had a little lamb".splitn(3, ' '); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// split.next(); - /// assert_eq!(split.as_str(), "had a little lamb"); + /// assert_eq!(split.remainder(), Some("had a little lamb")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } impl<'a, P: Pattern<'a>> RSplitN<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_as_str)] + /// #![feature(str_split_remainder)] /// let mut split = "Mary had a little lamb".rsplitn(3, ' '); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// split.next(); - /// assert_eq!(split.as_str(), "Mary had a little"); + /// assert_eq!(split.remainder(), Some("Mary had a little")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } @@ -1239,22 +1252,22 @@ impl<'a> SplitWhitespace<'a> { /// # Examples /// /// ``` - /// #![feature(str_split_whitespace_as_str)] + /// #![feature(str_split_whitespace_remainder)] /// /// let mut split = "Mary had a little lamb".split_whitespace(); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// /// split.next(); - /// assert_eq!(split.as_str(), "had a little lamb"); + /// assert_eq!(split.remainder(), Some("had a little lamb")); /// /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] #[must_use] - #[unstable(feature = "str_split_whitespace_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.inner.iter.as_str() + #[unstable(feature = "str_split_whitespace_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.inner.iter.remainder() } } @@ -1290,32 +1303,34 @@ impl<'a> DoubleEndedIterator for SplitAsciiWhitespace<'a> { impl FusedIterator for SplitAsciiWhitespace<'_> {} impl<'a> SplitAsciiWhitespace<'a> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_whitespace_as_str)] + /// #![feature(str_split_whitespace_remainder)] /// /// let mut split = "Mary had a little lamb".split_ascii_whitespace(); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// /// split.next(); - /// assert_eq!(split.as_str(), "had a little lamb"); + /// assert_eq!(split.remainder(), Some("had a little lamb")); /// /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] #[must_use] - #[unstable(feature = "str_split_whitespace_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { + #[unstable(feature = "str_split_whitespace_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { if self.inner.iter.iter.finished { - return ""; + return None; } // SAFETY: Slice is created from str. - unsafe { crate::str::from_utf8_unchecked(&self.inner.iter.iter.v) } + Some(unsafe { crate::str::from_utf8_unchecked(&self.inner.iter.iter.v) }) } } @@ -1358,23 +1373,25 @@ impl<'a, P: Pattern<'a, Searcher: ReverseSearcher<'a>>> DoubleEndedIterator impl<'a, P: Pattern<'a>> FusedIterator for SplitInclusive<'a, P> {} impl<'a, P: Pattern<'a>> SplitInclusive<'a, P> { - /// Returns remainder of the split string + /// Returns remainder of the split string. + /// + /// If the iterator is empty, returns `None`. /// /// # Examples /// /// ``` - /// #![feature(str_split_inclusive_as_str)] + /// #![feature(str_split_inclusive_remainder)] /// let mut split = "Mary had a little lamb".split_inclusive(' '); - /// assert_eq!(split.as_str(), "Mary had a little lamb"); + /// assert_eq!(split.remainder(), Some("Mary had a little lamb")); /// split.next(); - /// assert_eq!(split.as_str(), "had a little lamb"); + /// assert_eq!(split.remainder(), Some("had a little lamb")); /// split.by_ref().for_each(drop); - /// assert_eq!(split.as_str(), ""); + /// assert_eq!(split.remainder(), None); /// ``` #[inline] - #[unstable(feature = "str_split_inclusive_as_str", issue = "77998")] - pub fn as_str(&self) -> &'a str { - self.0.as_str() + #[unstable(feature = "str_split_inclusive_remainder", issue = "77998")] + pub fn remainder(&self) -> Option<&'a str> { + self.0.remainder() } } diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs index 45fd2caae..ab2f8520e 100644 --- a/library/core/src/str/mod.rs +++ b/library/core/src/str/mod.rs @@ -368,7 +368,7 @@ impl str { #[inline(always)] pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] { // SAFETY: the cast from `&str` to `&[u8]` is safe since `str` - // has the same layout as `&[u8]` (only libstd can make this guarantee). + // has the same layout as `&[u8]` (only std can make this guarantee). // The pointer dereference is safe since it comes from a mutable reference which // is guaranteed to be valid for writes. unsafe { &mut *(self as *mut str as *mut [u8]) } @@ -970,8 +970,10 @@ impl str { /// An iterator over the lines of a string, as string slices. /// - /// Lines are ended with either a newline (`\n`) or a carriage return with - /// a line feed (`\r\n`). + /// Lines are split at line endings that are either newlines (`\n`) or + /// sequences of a carriage return followed by a line feed (`\r\n`). + /// + /// Line terminators are not included in the lines returned by the iterator. /// /// The final line ending is optional. A string that ends with a final line /// ending will return the same lines as an otherwise identical string diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index edc68d6fa..14367eb09 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -1786,6 +1786,42 @@ impl AtomicPtr { // SAFETY: data races are prevented by atomic intrinsics. unsafe { atomic_xor(self.p.get(), core::ptr::invalid_mut(val), order).cast() } } + + /// Returns a mutable pointer to the underlying pointer. + /// + /// Doing non-atomic reads and writes on the resulting integer can be a data race. + /// This method is mostly useful for FFI, where the function signature may use + /// `*mut *mut T` instead of `&AtomicPtr`. + /// + /// Returning an `*mut` pointer from a shared reference to this atomic is safe because the + /// atomic types work with interior mutability. All modifications of an atomic change the value + /// through a shared reference, and can do so safely as long as they use atomic operations. Any + /// use of the returned raw pointer requires an `unsafe` block and still has to uphold the same + /// restriction: operations on it must be atomic. + /// + /// # Examples + /// + /// ```ignore (extern-declaration) + /// #![feature(atomic_mut_ptr)] + //// use std::sync::atomic::AtomicPtr; + /// + /// extern "C" { + /// fn my_atomic_op(arg: *mut *mut u32); + /// } + /// + /// let mut value = 17; + /// let atomic = AtomicPtr::new(&mut value); + /// + /// // SAFETY: Safe as long as `my_atomic_op` is atomic. + /// unsafe { + /// my_atomic_op(atomic.as_mut_ptr()); + /// } + /// ``` + #[inline] + #[unstable(feature = "atomic_mut_ptr", reason = "recently added", issue = "66893")] + pub fn as_mut_ptr(&self) -> *mut *mut T { + self.p.get() + } } #[cfg(target_has_atomic_load_store = "8")] @@ -2678,9 +2714,9 @@ macro_rules! atomic_int { #[doc = concat!(" fn my_atomic_op(arg: *mut ", stringify!($int_type), ");")] /// } /// - #[doc = concat!("let mut atomic = ", stringify!($atomic_type), "::new(1);")] + #[doc = concat!("let atomic = ", stringify!($atomic_type), "::new(1);")] /// - // SAFETY: Safe as long as `my_atomic_op` is atomic. + /// // SAFETY: Safe as long as `my_atomic_op` is atomic. /// unsafe { /// my_atomic_op(atomic.as_mut_ptr()); /// } diff --git a/library/core/src/sync/exclusive.rs b/library/core/src/sync/exclusive.rs index c65c27500..301ad41c9 100644 --- a/library/core/src/sync/exclusive.rs +++ b/library/core/src/sync/exclusive.rs @@ -138,7 +138,7 @@ impl Exclusive { unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().inner) } } - /// Build a _mutable_ references to an `Exclusive` from + /// Build a _mutable_ reference to an `Exclusive` from /// a _mutable_ reference to a `T`. This allows you to skip /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] @@ -149,7 +149,7 @@ impl Exclusive { unsafe { &mut *(r as *mut T as *mut Exclusive) } } - /// Build a _pinned mutable_ references to an `Exclusive` from + /// Build a _pinned mutable_ reference to an `Exclusive` from /// a _pinned mutable_ reference to a `T`. This allows you to skip /// building an `Exclusive` with [`Exclusive::new`]. #[unstable(feature = "exclusive_wrapper", issue = "98407")] diff --git a/library/core/src/task/poll.rs b/library/core/src/task/poll.rs index f1dc4f7b5..25b61c0e6 100644 --- a/library/core/src/task/poll.rs +++ b/library/core/src/task/poll.rs @@ -9,7 +9,7 @@ use crate::task::Ready; /// scheduled to receive a wakeup instead. #[must_use = "this `Poll` may be a `Pending` variant, which should be handled"] #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)] -#[cfg_attr(not(bootstrap), lang = "Poll")] +#[lang = "Poll"] #[stable(feature = "futures_api", since = "1.36.0")] pub enum Poll { /// Represents that a value is immediately ready. diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs index 0cff972df..89adfccd9 100644 --- a/library/core/src/task/wake.rs +++ b/library/core/src/task/wake.rs @@ -104,7 +104,7 @@ pub struct RawWakerVTable { /// pointer. wake_by_ref: unsafe fn(*const ()), - /// This function gets called when a [`RawWaker`] gets dropped. + /// This function gets called when a [`Waker`] gets dropped. /// /// The implementation of this function must make sure to release any /// resources that are associated with this instance of a [`RawWaker`] and @@ -151,7 +151,7 @@ impl RawWakerVTable { /// /// # `drop` /// - /// This function gets called when a [`RawWaker`] gets dropped. + /// This function gets called when a [`Waker`] gets dropped. /// /// The implementation of this function must make sure to release any /// resources that are associated with this instance of a [`RawWaker`] and @@ -174,6 +174,7 @@ impl RawWakerVTable { /// Currently, `Context` only serves to provide access to a [`&Waker`](Waker) /// which can be used to wake the current task. #[stable(feature = "futures_api", since = "1.36.0")] +#[cfg_attr(not(bootstrap), lang = "Context")] pub struct Context<'a> { waker: &'a Waker, // Ensure we future-proof against variance changes by forcing @@ -181,6 +182,9 @@ pub struct Context<'a> { // are contravariant while return-position lifetimes are // covariant). _marker: PhantomData &'a ()>, + // Ensure `Context` is `!Send` and `!Sync` in order to allow + // for future `!Send` and / or `!Sync` fields. + _marker2: PhantomData<*mut ()>, } impl<'a> Context<'a> { @@ -190,7 +194,7 @@ impl<'a> Context<'a> { #[must_use] #[inline] pub const fn from_waker(waker: &'a Waker) -> Self { - Context { waker, _marker: PhantomData } + Context { waker, _marker: PhantomData, _marker2: PhantomData } } /// Returns a reference to the [`Waker`] for the current task. diff --git a/library/core/src/unicode/mod.rs b/library/core/src/unicode/mod.rs index 72fa059b7..e1faa407d 100644 --- a/library/core/src/unicode/mod.rs +++ b/library/core/src/unicode/mod.rs @@ -17,7 +17,7 @@ mod unicode_data; #[stable(feature = "unicode_version", since = "1.45.0")] pub const UNICODE_VERSION: (u8, u8, u8) = unicode_data::UNICODE_VERSION; -// For use in liballoc, not re-exported in libstd. +// For use in alloc, not re-exported in std. pub use unicode_data::{ case_ignorable::lookup as Case_Ignorable, cased::lookup as Cased, conversions, }; -- cgit v1.2.3