Tracking issue for `Cell::get_mut` and `RefCell::get_mut`

[tbu-]

These methods allow one to obtain a mutable reference to the interior of these cells if you have a mutable reference to the cells themselves.

[tbu-]

As stated in #32565 (comment), I think that a better name for these methods would be as_mut.

[alexcrichton]

🔔 This issue is now entering its final comment period for stabilization 🔔

The libs team was unfortunately a little late on stabilizations this cycle, but we're thinking of probably doing a backport of stabilizations partway through the beta cycle. This API also follows existing conventions so should be an easy stabilization!

[tbu-]

Looking through the naming convention again, it seems that get is only used for conversions or functions that are not cheap or free, e.g. accessing elements of containers, slices, checking the poisoning state of a mutex and returning the element (with the exception of Unique::get_mut, which isn't stabilized yet).

However, as is often used for this kind of conversion, e.g. Option::as_mut.

I don't think get fits here.

[alexcrichton]

Ah yes I forgot to mention, but the libs team did indeed discuss the name and concluded that get_mut is the convention here. The get_* prefix is used for containers such as vectors, maps, I/O wrappers, synchronization primitives, etc. The as_* prefix is intended for conversions.

Because these are "containers" and these methods aren't performing conversions, we concluded the appropriate name was get_mut

[alexcrichton]

The libs team discussed this issue during triage yesterday and the decision was to stabilize. We realize that the FCP for this issue was pretty short, however, so please comment with any objections you might have! We're very willing to backport an un-stabilization for the few APIs we have this cycle.