Repository: rust
Issue: Tracking Issue for `Atomic*::from_ptr` and `const_atomic_from_ptr`
Labels: C-tracking-issue,T-libs,A-atomic

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Feature gate: `#![feature(atomic_from_ptr)]`, `#![feature(const_atomic_from_ptr)]`

This is a tracking issue for `Atomic*::from_ptr` set of functions.

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### Public API

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```rust
// core::atomic

impl AtomicBool { pub const unsafe fn from_ptr<'a>(ptr: *mut bool) -> &'a AtomicBool; }

impl<T> AtomicPtr<T> { pub const unsafe fn from_ptr<'a>(ptr: *mut *mut T) -> &'a AtomicPtr<T>; }

impl AtomicU8    { pub const unsafe fn from_ptr<'a>(ptr: *mut u8)    -> &'a AtomicU8;    }
impl AtomicU16   { pub const unsafe fn from_ptr<'a>(ptr: *mut u16)   -> &'a AtomicU16;   }
impl AtomicU32   { pub const unsafe fn from_ptr<'a>(ptr: *mut u32)   -> &'a AtomicU32;   }
impl AtomicU64   { pub const unsafe fn from_ptr<'a>(ptr: *mut u64)   -> &'a AtomicU64;   }
impl AtomicUsize { pub const unsafe fn from_ptr<'a>(ptr: *mut usize) -> &'a AtomicUsize; }

impl AtomicI8    { pub const unsafe fn from_ptr<'a>(ptr: *mut i8)    -> &'a AtomicI8;    }
impl AtomicI16   { pub const unsafe fn from_ptr<'a>(ptr: *mut i16)   -> &'a AtomicI16;   }
impl AtomicI32   { pub const unsafe fn from_ptr<'a>(ptr: *mut i32)   -> &'a AtomicI32;   }
impl AtomicI64   { pub const unsafe fn from_ptr<'a>(ptr: *mut i64)   -> &'a AtomicI64;   }
impl AtomicIsize { pub const unsafe fn from_ptr<'a>(ptr: *mut isize) -> &'a AtomicIsize; }
```

### Steps / History

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- [x] Implementation: #108540
- [x] Final comment period (FCP)[^1]
- [x] Stabilization PR - https://github.com/rust-lang/rust/pull/115719

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### Unresolved Questions

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- None yet.

[^1]: https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html