lint iterator.map(|x| x)

[matthiaskrgr]

This was most likely left over after some refactoring and can be removed entirely (at least I can't think of a reason to have .map(|x| x) in the code right now..)

[llogiq]

Note that this will apply type adjustments on x where applicable. However, the redundant_closure lint already has a check for adjustments which can be copied to this new lint.

[theo-lw]

I'd like to try my hand at this!

[giraffate]

Hi, is this issue already resolved? If so, it would be better to close this.

[JohnTitor]

Closing in favor of #5694.