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Constify conversion traits #144289

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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
18 changes: 12 additions & 6 deletions library/alloc/src/boxed.rs
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Expand Up @@ -1942,7 +1942,8 @@ impl<T: ?Sized, A: Allocator> fmt::Pointer for Box<T, A> {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized, A: Allocator> Deref for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const Deref for Box<T, A> {
type Target = T;

fn deref(&self) -> &T {
Expand All @@ -1951,7 +1952,8 @@ impl<T: ?Sized, A: Allocator> Deref for Box<T, A> {
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized, A: Allocator> DerefMut for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const DerefMut for Box<T, A> {
fn deref_mut(&mut self) -> &mut T {
&mut **self
}
Expand Down Expand Up @@ -2028,28 +2030,32 @@ unsafe impl<T: ?Sized, A: Allocator> PinCoerceUnsized for Box<T, A> {}
impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T, Global> {}

#[stable(feature = "box_borrow", since = "1.1.0")]
impl<T: ?Sized, A: Allocator> Borrow<T> for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const Borrow<T> for Box<T, A> {
fn borrow(&self) -> &T {
&**self
}
}

#[stable(feature = "box_borrow", since = "1.1.0")]
impl<T: ?Sized, A: Allocator> BorrowMut<T> for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const BorrowMut<T> for Box<T, A> {
fn borrow_mut(&mut self) -> &mut T {
&mut **self
}
}

#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")]
impl<T: ?Sized, A: Allocator> AsRef<T> for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const AsRef<T> for Box<T, A> {
fn as_ref(&self) -> &T {
&**self
}
}

#[stable(since = "1.5.0", feature = "smart_ptr_as_ref")]
impl<T: ?Sized, A: Allocator> AsMut<T> for Box<T, A> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<T: ?Sized, A: Allocator> const AsMut<T> for Box<T, A> {
fn as_mut(&mut self) -> &mut T {
&mut **self
}
Expand Down
28 changes: 21 additions & 7 deletions library/alloc/src/boxed/thin.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@

use core::error::Error;
use core::fmt::{self, Debug, Display, Formatter};
use core::intrinsics::const_eval_select;
#[cfg(not(no_global_oom_handling))]
use core::intrinsics::{const_allocate, const_make_global};
use core::marker::PhantomData;
Expand Down Expand Up @@ -138,7 +139,8 @@ impl<T: ?Sized + Display> Display for ThinBox<T> {
}

#[unstable(feature = "thin_box", issue = "92791")]
impl<T: ?Sized> Deref for ThinBox<T> {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
impl<T: ?Sized> const Deref for ThinBox<T> {
type Target = T;

fn deref(&self) -> &T {
Expand All @@ -150,6 +152,7 @@ impl<T: ?Sized> Deref for ThinBox<T> {
}

#[unstable(feature = "thin_box", issue = "92791")]
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
impl<T: ?Sized> DerefMut for ThinBox<T> {
fn deref_mut(&mut self) -> &mut T {
let value = self.data();
Expand All @@ -172,17 +175,20 @@ impl<T: ?Sized> Drop for ThinBox<T> {

#[unstable(feature = "thin_box", issue = "92791")]
impl<T: ?Sized> ThinBox<T> {
fn meta(&self) -> <T as Pointee>::Metadata {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
const fn meta(&self) -> <T as Pointee>::Metadata {
// Safety:
// - NonNull and valid.
unsafe { *self.with_header().header() }
}

fn data(&self) -> *mut u8 {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
const fn data(&self) -> *mut u8 {
self.with_header().value()
}

fn with_header(&self) -> &WithHeader<<T as Pointee>::Metadata> {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
const fn with_header(&self) -> &WithHeader<<T as Pointee>::Metadata> {
// SAFETY: both types are transparent to `NonNull<u8>`
unsafe { &*((&raw const self.ptr) as *const WithHeader<_>) }
}
Expand Down Expand Up @@ -398,7 +404,8 @@ impl<H> WithHeader<H> {
}
}

fn header(&self) -> *mut H {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
const fn header(&self) -> *mut H {
// Safety:
// - At least `size_of::<H>()` bytes are allocated ahead of the pointer.
// - We know that H will be aligned because the middle pointer is aligned to the greater
Expand All @@ -407,11 +414,18 @@ impl<H> WithHeader<H> {
// will always result in an aligned header pointer, it just may not point to the
// beginning of the allocation.
let hp = unsafe { self.0.as_ptr().sub(Self::header_size()) as *mut H };
debug_assert!(hp.is_aligned());

const fn ignore_alignment_const<H>(_hp: *mut H) {}
fn check_alignment_rt<H>(hp: *mut H) {
debug_assert!(hp.is_aligned());
}
const_eval_select((hp,), ignore_alignment_const, check_alignment_rt);

hp
}

fn value(&self) -> *mut u8 {
#[rustc_const_unstable(feature = "const_from", issue = "143773")]
const fn value(&self) -> *mut u8 {
self.0.as_ptr()
}

Expand Down
54 changes: 36 additions & 18 deletions library/alloc/src/bstr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,23 +48,27 @@ pub struct ByteString(pub Vec<u8>);

impl ByteString {
#[inline]
pub(crate) fn as_bytes(&self) -> &[u8] {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
pub(crate) const fn as_bytes(&self) -> &[u8] {
&self.0
}

#[inline]
pub(crate) fn as_bytestr(&self) -> &ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
pub(crate) const fn as_bytestr(&self) -> &ByteStr {
ByteStr::new(&self.0)
}

#[inline]
pub(crate) fn as_mut_bytestr(&mut self) -> &mut ByteStr {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
pub(crate) const fn as_mut_bytestr(&mut self) -> &mut ByteStr {
ByteStr::from_bytes_mut(&mut self.0)
}
}

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

#[inline]
Expand All @@ -74,7 +78,8 @@ impl Deref for ByteString {
}

#[unstable(feature = "bstr", issue = "134915")]
impl DerefMut for ByteString {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const DerefMut for ByteString {
#[inline]
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
Expand All @@ -101,47 +106,53 @@ impl fmt::Display for ByteString {
}

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

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

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

#[unstable(feature = "bstr", issue = "134915")]
impl AsMut<ByteStr> for ByteString {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const AsMut<ByteStr> for ByteString {
#[inline]
fn as_mut(&mut self) -> &mut ByteStr {
self.as_mut_bytestr()
}
}

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

#[unstable(feature = "bstr", issue = "134915")]
impl Borrow<ByteStr> for ByteString {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const Borrow<ByteStr> for ByteString {
#[inline]
fn borrow(&self) -> &ByteStr {
self.as_bytestr()
Expand All @@ -152,15 +163,17 @@ impl Borrow<ByteStr> for ByteString {
// `impl Borrow<ByteStr> for String` omitted to avoid inference failures

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

#[unstable(feature = "bstr", issue = "134915")]
impl BorrowMut<ByteStr> for ByteString {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const BorrowMut<ByteStr> for ByteString {
#[inline]
fn borrow_mut(&mut self) -> &mut ByteStr {
self.as_mut_bytestr()
Expand Down Expand Up @@ -211,7 +224,8 @@ impl Default for ByteString {
// }

#[unstable(feature = "bstr", issue = "134915")]
impl From<ByteString> for Vec<u8> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl const From<ByteString> for Vec<u8> {
#[inline]
fn from(s: ByteString) -> Self {
s.0
Expand Down Expand Up @@ -245,15 +259,17 @@ impl<'a> From<&'a ByteStr> for ByteString {
}

#[unstable(feature = "bstr", issue = "134915")]
impl<'a> From<ByteString> for Cow<'a, ByteStr> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a> const From<ByteString> for Cow<'a, ByteStr> {
#[inline]
fn from(s: ByteString) -> Self {
Cow::Owned(s)
}
}

#[unstable(feature = "bstr", issue = "134915")]
impl<'a> From<&'a ByteString> for Cow<'a, ByteStr> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a> const From<&'a ByteString> for Cow<'a, ByteStr> {
#[inline]
fn from(s: &'a ByteString) -> Self {
Cow::Borrowed(s.as_bytestr())
Expand Down Expand Up @@ -578,7 +594,8 @@ impl TryFrom<ByteString> for String {
}

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

#[inline]
Expand All @@ -598,7 +615,8 @@ impl Clone for Box<ByteStr> {
}

#[unstable(feature = "bstr", issue = "134915")]
impl<'a> From<&'a ByteStr> for Cow<'a, ByteStr> {
#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
impl<'a> const From<&'a ByteStr> for Cow<'a, ByteStr> {
#[inline]
fn from(s: &'a ByteStr) -> Self {
Cow::Borrowed(s)
Expand Down
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