New lint: redundant_slicing

[Jarcho]

changelog: Added lint: redundant_slicing
fixes #6519

This will trigger on any type which implements Index<RangeFull> that returns the input type. This would be a false positive if the implementation does something other than return itself, but I'm not sure why you would ever want to do that.

[rust-highfive]

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[flip1995]

but I'm not sure why you would ever want to do that.

If I learned anything from maintaining Clippy, it is that someone out there always does something you don't expect. But your argument that this should be noted in the code is correct. And what better way to note this than with a clippy-allow?

[bors]

☔ The latest upstream changes (presumably #6538) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #6500) made this pull request unmergeable. Please resolve the merge conflicts.

[flip1995]

@bors r+

Thanks!

[bors]

📌 Commit 9146a77 has been approved by flip1995

[bors]

⌛ Testing commit 9146a77 with merge 990e2b3...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing 990e2b3 to master...