Use associated items of char instead of freestanding items in core::char

[lukas-code]

The associated functions and constants on char have been stable since 1.52 and the freestanding items have soft-deprecated since 1.62 (#95566). This PR marks them as "deprecated in future", similar to the integer and floating point modules (core::{i32, f32} etc) replaces all uses of core::char::* with char::* to prepare for future deprecation of core::char::*.

[rustbot]

r? @scottmcm

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If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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[scottmcm]

Is there a libs-api decision to do this? I think future-deprecated shows up in the docs, so it's probably up to them whether to do this.

Alternatively, if you wanted to split this into the changes to stop using those constants, in favour of the associated ones, and a separate one to actually do the deprecated, I'd be happy to sign of on no longer using these constants in other examples and such.

@rustbot author

[lukas-code]

Yeah, the idea was that the deprecation message shows up in the docs, because to me the current docs read like these are already deprecated.

But if the deprecation needs a libs-api decision we can land it separately. I've removed the deprecation from this PR for now, but kept the updates from core::char::* to char::*, including those in doc examples.

@rustbot ready

[scottmcm]

Thanks! Updating the library and particularly the docs like this is a great improvement. (And, unlike deprecations, something I can sign off on 🙃)

@bors r+ rollup

[bors]

📌 Commit 76e216f has been approved by scottmcm

It is now in the queue for this repository.

[bors]

⌛ Testing commit 76e216f with merge adb4bfd...

[bors]

☀️ Test successful - checks-actions
Approved by: scottmcm
Pushing adb4bfd to master...

[rust-timer]

Finished benchmarking commit (adb4bfd): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.1%	[-5.1%, -5.1%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.9%	[2.9%, 2.9%]	1
Regressions ❌ (secondary)	3.1%	[3.1%, 3.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.9%	[2.9%, 2.9%]	1

Cycles

This benchmark run did not return any relevant results for this metric.