Ralf Jung b670b86353 Rollup merge of #76936 - danielhenrymantilla:unsafecell_get_mut, r=RalfJung ... Add non-`unsafe` `.get_mut()` for `Unsafecell` - Tracking issue: https://github.com/rust-lang/rust/issues/76943 As discussed in: https://internals.rust-lang.org/t/add-non-unsafe-get-mut-for-unsafecell/12407 - ### [Rendered documentation](https://modest-dubinsky-1f9f47.netlify.app/core/cell/struct.unsafecell) This PR tries to move the sound `&mut UnsafeCell<T> -> &mut T` projection that all the "downstream" constructions were already relying on, up to the root abstraction, where it rightfully belongs, and officially blessing it. - this **helps reduce the amount of `unsafe` snippets out there** (_c.f._, the second commit of this PR: 09503fd1b3) The fact that this getter is now expose for `UnsafeCell<T>` itself, will also help convey the idea that **`UnsafeCell` is not magical _w.r.t._ `&mut` accesses**, contrary to what some people incorrectly think. - Even the standard library itself at some point had such a confusion, _c.f._ this comment where there is a mention of multi-threaded (and thus _shared_) access despite dealing with exclusive references over unique ownership: 59fb88d061/library/core/src/cell.rs (L498-L499) r? @RalfJung		2020-09-21 10:40:37 +02:00
..
benches	flt2dec: properly handle uninitialized memory	2020-09-02 12:41:38 +02:00
src	Rollup merge of #76936 - danielhenrymantilla:unsafecell_get_mut, r=RalfJung	2020-09-21 10:40:37 +02:00
tests	Move const tests for Option to library\core	2020-09-20 22:42:14 +02:00
Cargo.toml