Tracking issue for associated functions and consts of std::char.

[eduardosm]

The std::char module defines functions that could be instead associated methods of the char type (e.g., decode_utf16). Making them associated to the char type allows to use directly char::method instead of std::char::method. Similarly, the std::char::MAX and std::char::REPLACEMENT_CHARACTER could also be associated constants (like done with integer constants in #68952).

[eduardosm]

I can help to implement to do this. This is what I would do:

• Move the functions and constants into impl char and make them unstable (with features assoc_char_funcs and assoc_char_consts).
• Implement the non-associated versions on top of the associated ones.

[eduardosm]

Implement the non-associated versions on top of the associated ones.

Given the module structure inside the core::char module, I think it would be better to implement the associated functions on top of the other functions.

[eduardosm]

This is currently the issue pointed as tracking issue for the new features added in #71854, so this issue should be reopened or a proper tracking issue should be created.

[kornelski]

Are there any blockers to stabilizing this?

[gilescope]

This would be great to stabilise as it trips new users up that the methods aren't available on char in stable rust at the moment.

[bstrie]

I'm assuming that no separate RFC is necessary here since, speaking as the author of RFC 2700, it was simple oversight on my part that the wannabe associated items on char were overlooked. I'll submit a stabilization PR for consideration.