I find this more consistent with RefCell's equivalent method.

… r=m-ou-se

Stabilize span_open() and span_close().

This proposes to stabilize `Group::span_open()` and `Group::span_close()`.

These are part of the `proc_macro_span` feature gate tracked in rust-lang#54725

Most of the features gated behind `proc_macro_span` are about source location information (file path, line and column information), expansion information (parent()), source_text(), etc. Those are not ready for stabilizaiton. However, getting the span of the `(` and `)` separately instead of only of the entire `(...)` can be very useful in proc macros, and doesn't seem blocked on anything that all the other parts of `proc_macro_span` are blocked on. So, this renames the feature gate for those two functions to `proc_macro_group_span` and stabilizes them.

…hnTitor

Use as_secs_f64 in JunitFormatter

cc ``@andoriyu``

…d-versions-layout, r=GuillaumeGomez

Fix rustdoc stabilized versions layout

Fixes rust-lang#86342
r? ``@GuillaumeGomez``

…rtichaut

Add pattern walking support to THIR walker

Suggested in rust-lang#85263 (comment), this splits off the support for pattern walking in THIR from rust-lang#85263. This has no observable effect on THIR unsafety checking, since it is not currently possible to trigger unsafety from the THIR checker using the additional patterns or constants that are now walked. THIR patterns are walked in source code order.

r? `@LeSeulArtichaut`

Alter std::cell::Cell::get_mut documentation

I felt that there was some inconsistency between between Cell and RefCell with regards to their `get_mut` method documentation: `RefCell` flags this method as "unusual" in that it takes `&mut self`, while `Cell` does not. I attempted to flag this in `Cell`s documentation as well, and point to `RefCell`s method in the case where it is required.

Find relevant parts of docs and the new version below.

The current docs for `Cell::get_mut`:
> Returns a mutable reference to the underlying data.
This call borrows Cell mutably (at compile-time) which guarantees that we possess the only reference.

And `RefCell::get_mut`:
> Returns a mutable reference to the underlying data.
 This call borrows `RefCell` mutably (at compile-time) so there is no need for dynamic checks.
However be cautious: this method expects self to be mutable, which is generally not the case when using a `RefCell`. Take a look at the `borrow_mut` method instead if self isn’t mutable.
Also, please be aware that this method is only for special circumstances and is usually not what you want. In case of doubt, use `borrow_mut` instead.

My attempt to make `Cell::get_mut` clearer:
> Returns a mutable reference to the underlying data.
This call borrows `Cell` mutably (at compile-time) which guaranteesthat we possess the only reference.
However be cautious: this method expects `self` to be mutable, which is generally not the case when using a `Cell`. If you require interior mutability by reference, consider using `RefCell` which provides run-time checked mutable borrows through its `borrow_mut` method.

Use `map_or` instead of open-coding it

``@rustbot`` modify labels +C-cleanup +T-compiler

…=Aaron1011

Lint for unused borrows as part of UNUSED_MUST_USE

close rust-lang#76264

base on rust-lang#76894

r? `@RalfJung`

add various coments to explain how the TAIT code works

r? `@oli-obk`

…r=m-ou-se

Update library tracking issue for libs-api rename.

…tichaut

Fix ICE with `#[repr(simd)]` on enum

This pull request fixes rust-lang#83505. `#[repr(simd)]` may only be applied to structs, which correctly causes `E0517` for the example given in rust-lang#83505, but the compiler attempts to recover from this error, which leads to an ICE later, when `.non_enum_variant()` is called on the `AdtDef`. I have added a check that prevents this from happening.

stdlib: Fix typo in internal RefCell docs

`BorroeError` => `BorrowError` in [cell.rs](https://github.com/rust-lang/rust/blob/master/library/core/src/cell.rs#L581)