[experiment] Add MustClone and impl Copy+MustClone on Range{,From,Inclusive}.

[eddyb]

Background: (second half of) rust-lang/rfcs#2848 (comment).

I'm opening this for two reasons:

• demonstrating the (relatively simple) implementation (though it could use specialized diagnostics)
• doing a crater run just in case simply having Range<_>: Copy breaks something through e.g. inference

[rust-highfive]

r? @petrochenkov

(rust_highfive has picked a reviewer for you, use r? to override)

[eddyb]

@bors try

[bors]

⌛ Trying commit 6cdd05313a732178776903a10d41edf154eea341 with merge 715ad67e8b83d57e72e8d58387d01d804162f99a...

[eddyb]

Oh and since this may require a fast path to not regress perf: @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[eddyb]

@bors try

[bors]

⌛ Trying commit 346ede0 with merge 6dab9ef81bafc73ee769b24a6ad263eca85520b4...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: 6dab9ef81bafc73ee769b24a6ad263eca85520b4 (6dab9ef81bafc73ee769b24a6ad263eca85520b4)

[rust-timer]

Queued 6dab9ef81bafc73ee769b24a6ad263eca85520b4 with parent 521d8d8, future comparison URL.

[eddyb]

@craterbot check

[craterbot]

👌 Experiment pr-77180 created and queued.
🤖 Automatically detected try build 6dab9ef81bafc73ee769b24a6ad263eca85520b4
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[rust-timer]

Finished benchmarking try commit (6dab9ef81bafc73ee769b24a6ad263eca85520b4): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never

[craterbot]

🚧 Experiment pr-77180 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[petrochenkov]

I like the general direction here, but I also agree with rust-lang/rfcs#2848 (comment) that it feels more like an "attribute + lint" case rather than a "trait + move error (?)", especially given that the trait is not used in generic context, only on concrete instances of ranges.

[craterbot]

🎉 Experiment pr-77180 is completed!
📊 10 regressed and 7 fixed (123440 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[petrochenkov]

One root regression due to #![deny(missing_copy_implementations)], no regressions due to Copy bounds.
Other regressions are spurious.

[eddyb]

Thanks! At least it being a lint means it shouldn't impact any crates that depend on conrod_core / kiss3d_conrod.
And having that lint trip is a nice way to confirm that something is different.

So we should be able to proceed here with an RFC or similar - though at the moment I don't have the bandwidth for anything like that, but if someone is interested in writing a #[must_clone] / trait MustClone RFC, feel free to show me drafts etc.

[eddyb]

I'm closing this experiment PR, please continue discussion over at rust-lang/rfcs#2848 (comment), to avoid fragmentation.