add lint [incorrect_clone_impl_on_copy_type]

[Centri3]

Split off from #10788.

Closes #10700

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changelog: new lint [incorrect_clone_impl_on_copy_type]
#10925

[rustbot]

r? @xFrednet

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[xFrednet]

@Centri3, you're on a real PR creation spree, damn! I'll review this one over the coming week :D

[bors]

☔ The latest upstream changes (presumably #10921) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #10916) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #10827) made this pull request unmergeable. Please resolve the merge conflicts.

[xFrednet]

I have a few smaller comments, but all of them should hopefully be simple to solve :). Please reach out, if you have any questions :)

[bors]

☔ The latest upstream changes (presumably #10934) made this pull request unmergeable. Please resolve the merge conflicts.

[Centri3]

I've looked at ryu's emittance of this lint, and it appears it is indeed correct; it implements Copy but Clone calls Buffer::new.
https://github.com/dtolnay/ryu/blob/6cdb3d1a0aaf62f762acf391d6b03f9a41f56c0e/src/buffer/mod.rs#LL82C1-L89C2
I've tested it with *self instead and there's no difference.

Running miri as well shows nothing out of the ordinary (though it already reported a violation of stacked borrows without such a change). Not sure whether it's slower or not, though.

[xFrednet]

This looks good to me. Thank you for the new lint!

@bors r+

[bors]

📌 Commit 10cc168 has been approved by xFrednet

It is now in the queue for this repository.

[bors]

⌛ Testing commit 10cc168 with merge 87b5f89...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: xFrednet
Pushing 87b5f89 to master...