Stabilize LocalKey::try_with

[ghost]

The LocalKey::try_with method is now stabilized.

LocalKey::state and LocalKeyState marked as deprecated. Although, is there any reason to keep them - should we perhaps remove them completely?

Closes #27716

r? @alexcrichton

[alexcrichton]

Thanks! Looks like there may be a tidy error though?

[ghost]

I had to switch LocalKey::try_with from feature thread_local_state to a new feature thread_local_try_with because tidy wants the whole future either stabilized or not.

Should be ok now.

[alexcrichton]

Oh hm looks like libstd is still using the deprecated items?

[ghost]

Passes on Travis now.

It seems LocalKeyState is only used by function print_to, which is called from macros print! and eprint!.

Do you think I should purge LocalKeyState from libstd? Is there any reason to deprecate, but still keep it?

[alexcrichton]

Nah I'd actually personally be on board with a complete removal of LocalKeyState if we can, the print_to function looks like it can for sure use try_with!

[alexcrichton]

@bors: r+

[bors]

📌 Commit 27fae2b has been approved by alexcrichton

[alexcrichton]

Looks like a libstd test may be failing?

[ghost]

Fixed. It was just a silly mistake - I accidentally deleted the HITS += 1 line.

[alexcrichton]

@bors: r+

[bors]

📌 Commit cb56b2d has been approved by alexcrichton