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Constify conversion traits (part 1) #145279

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15 changes: 11 additions & 4 deletions library/alloc/src/borrow.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,9 +17,11 @@ use crate::fmt;
use crate::string::String;

#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, B: ?Sized> Borrow<B> for Cow<'a, B>
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a, B: ?Sized> const Borrow<B> for Cow<'a, B>
where
B: ToOwned,
B::Owned: [const] Borrow<B>,
{
fn borrow(&self) -> &B {
&**self
Expand Down Expand Up @@ -326,9 +328,10 @@ impl<B: ?Sized + ToOwned> Cow<'_, B> {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<B: ?Sized + ToOwned> Deref for Cow<'_, B>
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<B: ?Sized + ToOwned> const Deref for Cow<'_, B>
where
B::Owned: Borrow<B>,
B::Owned: [const] Borrow<B>,
{
type Target = B;

Expand Down Expand Up @@ -439,7 +442,11 @@ where
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized + ToOwned> AsRef<T> for Cow<'_, T> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized + ToOwned> const AsRef<T> for Cow<'_, T>
where
T::Owned: [const] Borrow<T>,
{
fn as_ref(&self) -> &T {
self
}
Expand Down
6 changes: 4 additions & 2 deletions library/alloc/src/collections/mod.rs
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Expand Up @@ -128,17 +128,19 @@ pub use realalloc::collections::TryReserveErrorKind;
reason = "Uncertain how much info should be exposed",
issue = "48043"
)]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
#[cfg(not(test))]
impl From<TryReserveErrorKind> for TryReserveError {
impl const From<TryReserveErrorKind> for TryReserveError {
#[inline]
fn from(kind: TryReserveErrorKind) -> Self {
Self { kind }
}
}

#[unstable(feature = "try_reserve_kind", reason = "new API", issue = "48043")]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
#[cfg(not(test))]
impl From<LayoutError> for TryReserveErrorKind {
impl const From<LayoutError> for TryReserveErrorKind {
/// Always evaluates to [`TryReserveErrorKind::CapacityOverflow`].
#[inline]
fn from(_: LayoutError) -> Self {
Expand Down
3 changes: 2 additions & 1 deletion library/alloc/src/lib.rs
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Expand Up @@ -107,10 +107,10 @@
#![feature(char_max_len)]
#![feature(clone_to_uninit)]
#![feature(coerce_unsized)]
#![feature(const_convert)]
#![feature(const_default)]
#![feature(const_eval_select)]
#![feature(const_heap)]
#![feature(const_trait_impl)]
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Was listed under library features, and is actually a language feature. Since the diff doesn't make that clear.

#![feature(core_intrinsics)]
#![feature(deprecated_suggestion)]
#![feature(deref_pure_trait)]
Expand Down Expand Up @@ -167,6 +167,7 @@
#![feature(allow_internal_unstable)]
#![feature(cfg_sanitize)]
#![feature(const_precise_live_drops)]
#![feature(const_trait_impl)]
#![feature(coroutine_trait)]
#![feature(decl_macro)]
#![feature(dropck_eyepatch)]
Expand Down
1 change: 1 addition & 0 deletions library/alloctests/lib.rs
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Expand Up @@ -46,6 +46,7 @@
// Language features:
// tidy-alphabetical-start
#![feature(cfg_sanitize)]
#![feature(const_trait_impl)]
#![feature(dropck_eyepatch)]
#![feature(lang_items)]
#![feature(min_specialization)]
Expand Down
26 changes: 17 additions & 9 deletions library/core/src/array/mod.rs
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Expand Up @@ -198,38 +198,42 @@ impl Error for TryFromSliceError {
}

#[stable(feature = "try_from_slice_error", since = "1.36.0")]
#[rustc_const_unstable(feature = "const_try", issue = "74935")]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const From<Infallible> for TryFromSliceError {
fn from(x: Infallible) -> TryFromSliceError {
match x {}
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T, const N: usize> AsRef<[T]> for [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const AsRef<[T]> for [T; N] {
#[inline]
fn as_ref(&self) -> &[T] {
&self[..]
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T, const N: usize> AsMut<[T]> for [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const AsMut<[T]> for [T; N] {
#[inline]
fn as_mut(&mut self) -> &mut [T] {
&mut self[..]
}
}

#[stable(feature = "array_borrow", since = "1.4.0")]
impl<T, const N: usize> Borrow<[T]> for [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const Borrow<[T]> for [T; N] {
fn borrow(&self) -> &[T] {
self
}
}

#[stable(feature = "array_borrow", since = "1.4.0")]
impl<T, const N: usize> BorrowMut<[T]> for [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const BorrowMut<[T]> for [T; N] {
fn borrow_mut(&mut self) -> &mut [T] {
self
}
Expand All @@ -248,7 +252,8 @@ impl<T, const N: usize> BorrowMut<[T]> for [T; N] {
/// assert_eq!(512, u16::from_le_bytes(bytes_tail));
/// ```
#[stable(feature = "try_from", since = "1.34.0")]
impl<T, const N: usize> TryFrom<&[T]> for [T; N]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const TryFrom<&[T]> for [T; N]
where
T: Copy,
{
Expand All @@ -273,7 +278,8 @@ where
/// assert_eq!(512, u16::from_le_bytes(bytes_tail));
/// ```
#[stable(feature = "try_from_mut_slice_to_array", since = "1.59.0")]
impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T, const N: usize> const TryFrom<&mut [T]> for [T; N]
where
T: Copy,
{
Expand All @@ -298,7 +304,8 @@ where
/// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
/// ```
#[stable(feature = "try_from", since = "1.34.0")]
impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a, T, const N: usize> const TryFrom<&'a [T]> for &'a [T; N] {
type Error = TryFromSliceError;

#[inline]
Expand All @@ -320,7 +327,8 @@ impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
/// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
/// ```
#[stable(feature = "try_from", since = "1.34.0")]
impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a, T, const N: usize> const TryFrom<&'a mut [T]> for &'a mut [T; N] {
type Error = TryFromSliceError;

#[inline]
Expand Down
2 changes: 1 addition & 1 deletion library/core/src/ascii/ascii_char.rs
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Expand Up @@ -1156,7 +1156,7 @@ macro_rules! into_int_impl {
($($ty:ty)*) => {
$(
#[unstable(feature = "ascii_char", issue = "110998")]
#[rustc_const_unstable(feature = "const_try", issue = "74935")]
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const From<AsciiChar> for $ty {
#[inline]
fn from(chr: AsciiChar) -> $ty {
Expand Down
19 changes: 14 additions & 5 deletions library/core/src/borrow.rs
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Expand Up @@ -154,6 +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> {
/// Immutably borrows from an owned value.
///
Expand Down Expand Up @@ -185,6 +187,8 @@ 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> {
/// Mutably borrows from an owned value.
///
Expand All @@ -206,36 +210,41 @@ pub trait BorrowMut<Borrowed: ?Sized>: Borrow<Borrowed> {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Borrow<T> for T {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized> const Borrow<T> for T {
#[rustc_diagnostic_item = "noop_method_borrow"]
fn borrow(&self) -> &T {
self
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> BorrowMut<T> for T {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized> const BorrowMut<T> for T {
fn borrow_mut(&mut self) -> &mut T {
self
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Borrow<T> for &T {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized> const Borrow<T> for &T {
fn borrow(&self) -> &T {
self
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Borrow<T> for &mut T {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized> const Borrow<T> for &mut T {
fn borrow(&self) -> &T {
self
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> BorrowMut<T> for &mut T {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized> const BorrowMut<T> for &mut T {
fn borrow_mut(&mut self) -> &mut T {
self
}
Expand Down
45 changes: 30 additions & 15 deletions library/core/src/bstr/mod.rs
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Expand Up @@ -63,14 +63,16 @@ impl ByteStr {
/// ```
#[inline]
#[unstable(feature = "bstr", issue = "134915")]
pub fn new<B: ?Sized + AsRef<[u8]>>(bytes: &B) -> &Self {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
pub const fn new<B: ?Sized + [const] AsRef<[u8]>>(bytes: &B) -> &Self {
ByteStr::from_bytes(bytes.as_ref())
}

#[doc(hidden)]
#[unstable(feature = "bstr_internals", issue = "none")]
#[inline]
pub fn from_bytes(slice: &[u8]) -> &Self {
#[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
pub const fn from_bytes(slice: &[u8]) -> &Self {
// SAFETY: `ByteStr` is a transparent wrapper around `[u8]`, so we can turn a reference to
// the wrapped type into a reference to the wrapper type.
unsafe { &*(slice as *const [u8] as *const Self) }
Expand All @@ -79,7 +81,8 @@ impl ByteStr {
#[doc(hidden)]
#[unstable(feature = "bstr_internals", issue = "none")]
#[inline]
pub fn from_bytes_mut(slice: &mut [u8]) -> &mut Self {
#[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
pub const fn from_bytes_mut(slice: &mut [u8]) -> &mut Self {
// SAFETY: `ByteStr` is a transparent wrapper around `[u8]`, so we can turn a reference to
// the wrapped type into a reference to the wrapper type.
unsafe { &mut *(slice as *mut [u8] as *mut Self) }
Expand All @@ -88,20 +91,23 @@ impl ByteStr {
#[doc(hidden)]
#[unstable(feature = "bstr_internals", issue = "none")]
#[inline]
pub fn as_bytes(&self) -> &[u8] {
#[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
pub const fn as_bytes(&self) -> &[u8] {
&self.0
}

#[doc(hidden)]
#[unstable(feature = "bstr_internals", issue = "none")]
#[inline]
pub fn as_bytes_mut(&mut self) -> &mut [u8] {
#[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
pub const fn as_bytes_mut(&mut self) -> &mut [u8] {
&mut self.0
}
}

#[unstable(feature = "bstr", issue = "134915")]
impl Deref for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const Deref for ByteStr {
type Target = [u8];

#[inline]
Expand All @@ -111,7 +117,8 @@ impl Deref for ByteStr {
}

#[unstable(feature = "bstr", issue = "134915")]
impl DerefMut for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const DerefMut for ByteStr {
#[inline]
fn deref_mut(&mut self) -> &mut [u8] {
&mut self.0
Expand Down Expand Up @@ -185,15 +192,17 @@ impl fmt::Display for ByteStr {
}

#[unstable(feature = "bstr", issue = "134915")]
impl AsRef<[u8]> for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const AsRef<[u8]> for ByteStr {
#[inline]
fn as_ref(&self) -> &[u8] {
&self.0
}
}

#[unstable(feature = "bstr", issue = "134915")]
impl AsRef<ByteStr> for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const AsRef<ByteStr> for ByteStr {
#[inline]
fn as_ref(&self) -> &ByteStr {
self
Expand All @@ -203,15 +212,17 @@ impl AsRef<ByteStr> for ByteStr {
// `impl AsRef<ByteStr> for [u8]` omitted to avoid widespread inference failures

#[unstable(feature = "bstr", issue = "134915")]
impl AsRef<ByteStr> for str {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const AsRef<ByteStr> for str {
#[inline]
fn as_ref(&self) -> &ByteStr {
ByteStr::new(self)
}
}

#[unstable(feature = "bstr", issue = "134915")]
impl AsMut<[u8]> for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const AsMut<[u8]> for ByteStr {
#[inline]
fn as_mut(&mut self) -> &mut [u8] {
&mut self.0
Expand All @@ -225,7 +236,8 @@ impl AsMut<[u8]> for ByteStr {
// `impl Borrow<ByteStr> for str` omitted to avoid widespread inference failures

#[unstable(feature = "bstr", issue = "134915")]
impl Borrow<[u8]> for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const Borrow<[u8]> for ByteStr {
#[inline]
fn borrow(&self) -> &[u8] {
&self.0
Expand All @@ -235,7 +247,8 @@ impl Borrow<[u8]> for ByteStr {
// `impl BorrowMut<ByteStr> for [u8]` omitted to avoid widespread inference failures

#[unstable(feature = "bstr", issue = "134915")]
impl BorrowMut<[u8]> for ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const BorrowMut<[u8]> for ByteStr {
#[inline]
fn borrow_mut(&mut self) -> &mut [u8] {
&mut self.0
Expand Down Expand Up @@ -303,7 +316,8 @@ impl<'a> Default for &'a mut ByteStr {
// }

#[unstable(feature = "bstr", issue = "134915")]
impl<'a> TryFrom<&'a ByteStr> for &'a str {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a> const TryFrom<&'a ByteStr> for &'a str {
type Error = crate::str::Utf8Error;

#[inline]
Expand All @@ -313,7 +327,8 @@ impl<'a> TryFrom<&'a ByteStr> for &'a str {
}

#[unstable(feature = "bstr", issue = "134915")]
impl<'a> TryFrom<&'a mut ByteStr> for &'a mut str {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a> const TryFrom<&'a mut ByteStr> for &'a mut str {
type Error = crate::str::Utf8Error;

#[inline]
Expand Down
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