Fix some unnecessary_filter_map false positives

[smoelius]

This is a proposed fix for #4433.

It moves clone_or_copy_needed out of unnecessary_iter_cloned.rs and into methods::utils. It then adds a check of this function to unnecessary_filter_map::check.

Fixes #4433

changelog: none

[rust-highfive]

r? @llogiq

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[llogiq]

Good improvement! Thank you!

@bors r+

[bors]

📌 Commit d123ffc has been approved by llogiq

[bors]

⌛ Testing commit d123ffc with merge e511476...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: llogiq
Pushing e511476 to master...

[BartMassey]

@smoelius Thanks huge for the fix!

[smoelius]

@BartMassey No problem at all. By chance, have you had a chance to try it? (It's helpful to know a fix works on "real code.")

[BartMassey]

@smoelius Assuming the version of Clippy that has this PR has made it into nightly, I'm afraid it doesn't work for me. Do I need to build Clippy myself to try this?

[xFrednet]

Hey @BartMassey, I believe that this change has not yet made it into nightly yet. The repos are usually synced every two weeks. It should be available in one or two days (depending on when this will be done this week). 🙃

[smoelius]

Thanks for checking, @BartMassey. Thanks for responding, @xFrednet. :)

[BartMassey]

Thanks for the update! I can build it myself if needed, but it sounds like it's easier to just wait a bit at this point. Will let you know.

[xFrednet]

FYI @BartMassey, the fix has just been synced and should be available in the next nightly :)

[BartMassey]

@xFrednet Thanks! I'll give it a try shortly.