Support setting file accessed/modified timestamps

[joshtriplett]

Add struct FileTimes to contain the relevant file timestamps, since
most platforms require setting all of them at once. (This also allows
for future platform-specific extensions such as setting creation time.)

Add File::set_file_time to set the timestamps for a File.

Implement the sys backends for UNIX, macOS (which needs to fall back
to futimes before macOS 10.13 because it lacks futimens), Windows,
and WASI.

[rust-highfive]

Hey! It looks like you've submitted a new PR for the library teams!

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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[rust-highfive]

r? @m-ou-se

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[m-ou-se]

@bors r+

[bors]

📌 Commit 8f3fc2e5de8d702b93bb5cf1432630ab721f78d8 has been approved by m-ou-se

[m-ou-se]

@bors r-

Actually, set_times should probably take FileTimes by value rather than by reference, since it's a Copy type. Then it's also consistent with the signature of set_permissions.

[m-ou-se]

@bors r+

[bors]

📌 Commit 585767d has been approved by m-ou-se

[JohnTitor]

Failed in rollup: #98347 (comment)
Seems some tweaks are needed on macOS.
@bors r-

[joshtriplett]

@bors r=m-ou-se

[bors]

📌 Commit 11d9be6 has been approved by m-ou-se

It is now in the queue for this repository.

[bors]

⌛ Testing commit 11d9be6 with merge da0c22e89b671e47e40ae8382a0f78a1d7b7a9c7...

[bors]

💔 Test failed - checks-actions

[joshtriplett]

@bors r=m-ou-se

[bors]

📌 Commit f8061dd has been approved by m-ou-se

It is now in the queue for this repository.

[bors]

⌛ Testing commit f8061dd with merge eb5c3654b416912da280a0808ac36499e50d3bfe...

[bors]

💥 Test timed out

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[joshtriplett]

@bors retry

[bors]

⌛ Testing commit f8061dd with merge 1f5d8d4...

[bors]

☀️ Test successful - checks-actions
Approved by: m-ou-se
Pushing 1f5d8d4 to master...

[rust-timer]

Finished benchmarking commit (1f5d8d4): comparison url.

Instruction count

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

Max RSS (memory usage)

Results

• Primary benchmarks: 🎉 relevant improvement found
• Secondary benchmarks: mixed results

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	2.5%	2.5%	1
Improvements 🎉 (primary)	-2.3%	-2.3%	1
Improvements 🎉 (secondary)	-2.9%	-3.4%	2
All 😿🎉 (primary)	-2.3%	-2.3%	1

Cycles

Results

• Primary benchmarks: no relevant changes found
• Secondary benchmarks: 🎉 relevant improvement found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-3.1%	-3.1%	1
All 😿🎉 (primary)	N/A	N/A	0

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

Footnotes

1. the arithmetic mean of the percent change ↩ ↩²

2. number of relevant changes ↩ ↩²