Merge ref 'a09fbe2c8372' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: a09fbe2
Filtered ref: e8da14f32630072c76aeb944454175f4d8266918

This merge was created using https://github.com/rust-lang/josh-sync.

Author: RalfJung

Cargo.lock

@@ -154,9 +154,8 @@
 /// [`String`]: ../../std/string/struct.String.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "Borrow"]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-pub trait Borrow<Borrowed: ?Sized> {
+pub const trait Borrow<Borrowed: ?Sized> {
     /// Immutably borrows from an owned value.
     ///
     /// # Examples
@@ -187,9 +186,8 @@ pub trait Borrow<Borrowed: ?Sized> {
 /// for more information on borrowing as another type.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "BorrowMut"]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-pub trait BorrowMut<Borrowed: ?Sized>: Borrow<Borrowed> {
+pub const trait BorrowMut<Borrowed: ?Sized>: Borrow<Borrowed> {
     /// Mutably borrows from an owned value.
     ///
     /// # Examples

core/src/borrow.rs

@@ -191,8 +191,7 @@ mod uninit;
 #[rustc_diagnostic_item = "Clone"]
 #[rustc_trivial_field_reads]
 #[rustc_const_unstable(feature = "const_clone", issue = "142757")]
-#[const_trait]
-pub trait Clone: Sized {
+pub const trait Clone: Sized {
     /// Returns a duplicate of the value.
     ///
     /// Note that what "duplicate" means varies by type:

core/src/clone.rs

@@ -247,9 +247,8 @@ use crate::ops::ControlFlow;
     append_const_msg
 )]
 #[rustc_diagnostic_item = "PartialEq"]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
-pub trait PartialEq<Rhs: PointeeSized = Self>: PointeeSized {
+pub const trait PartialEq<Rhs: PointeeSized = Self>: PointeeSized {
     /// Tests for `self` and `other` values to be equal, and is used by `==`.
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]

core/src/cmp.rs

@@ -17,7 +17,7 @@ use crate::num::NonZero;
 /// - Neither `Self` nor `Rhs` have provenance, so integer comparisons are correct.
 /// - `<Self as PartialEq<Rhs>>::{eq,ne}` are equivalent to comparing the bytes.
 #[rustc_specialization_trait]
-#[const_trait]
+#[const_trait] // FIXME(const_trait_impl): Migrate to `const unsafe trait` once #146122 is fixed.
 pub(crate) unsafe trait BytewiseEq<Rhs = Self>:
     [const] PartialEq<Rhs> + Sized
 {

core/src/cmp/bytewise.rs

@@ -216,9 +216,8 @@ pub const fn identity<T>(x: T) -> T {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "AsRef"]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-pub trait AsRef<T: PointeeSized>: PointeeSized {
+pub const trait AsRef<T: PointeeSized>: PointeeSized {
     /// Converts this type into a shared reference of the (usually inferred) input type.
     #[stable(feature = "rust1", since = "1.0.0")]
     fn as_ref(&self) -> &T;
@@ -369,9 +368,8 @@ pub trait AsRef<T: PointeeSized>: PointeeSized {
 /// `&mut Vec<u8>`, for example, is the better choice (callers need to pass the correct type then).
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "AsMut"]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-pub trait AsMut<T: PointeeSized>: PointeeSized {
+pub const trait AsMut<T: PointeeSized>: PointeeSized {
     /// Converts this type into a mutable reference of the (usually inferred) input type.
     #[stable(feature = "rust1", since = "1.0.0")]
     fn as_mut(&mut self) -> &mut T;
@@ -450,8 +448,7 @@ pub trait AsMut<T: PointeeSized>: PointeeSized {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(search_unbox)]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-#[const_trait]
-pub trait Into<T>: Sized {
+pub const trait Into<T>: Sized {
     /// Converts this type into the (usually inferred) input type.
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -587,8 +584,7 @@ pub trait Into<T>: Sized {
 ))]
 #[doc(search_unbox)]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-#[const_trait]
-pub trait From<T>: Sized {
+pub const trait From<T>: Sized {
     /// Converts to this type from the input type.
     #[rustc_diagnostic_item = "from_fn"]
     #[must_use]
@@ -616,8 +612,7 @@ pub trait From<T>: Sized {
 #[rustc_diagnostic_item = "TryInto"]
 #[stable(feature = "try_from", since = "1.34.0")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-#[const_trait]
-pub trait TryInto<T>: Sized {
+pub const trait TryInto<T>: Sized {
     /// The type returned in the event of a conversion error.
     #[stable(feature = "try_from", since = "1.34.0")]
     type Error;
@@ -696,8 +691,7 @@ pub trait TryInto<T>: Sized {
 #[rustc_diagnostic_item = "TryFrom"]
 #[stable(feature = "try_from", since = "1.34.0")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
-#[const_trait]
-pub trait TryFrom<T>: Sized {
+pub const trait TryFrom<T>: Sized {
     /// The type returned in the event of a conversion error.
     #[stable(feature = "try_from", since = "1.34.0")]
     type Error;

core/src/convert/mod.rs

@@ -103,9 +103,8 @@ use crate::ascii::Char as AsciiChar;
 /// ```
 #[rustc_diagnostic_item = "Default"]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[const_trait]
 #[rustc_const_unstable(feature = "const_default", issue = "143894")]
-pub trait Default: Sized {
+pub const trait Default: Sized {
     /// Returns the "default value" for a type.
     ///
     /// Default values are often some kind of initial value, identity value, or anything else that