from_iter_instead_of_collect / needless_collect interaction questionable

[matthiaskrgr]

for _i in Vec::from_iter([1, 2, 3].iter()) {}

clippy will suggest to use .collect() instead of from_iter() here but blindly replacing will not work because .collect() will need some kind of type hint.

Them again

for _i in [1, 2, 3].iter().collect::<Vec<&i32>>() {}

does not trigger clippy::needless_collect (although it should!; neither does the first example) because we can iterate over

for _i in [1, 2, 3].iter() {}

directly.

[camsteffen]

Re-labeling as the first issue is fixed in #6657.

[y21]

Seems to be fixed, the second case also lints now: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=99d5028b5d63461da7aeb8466999d9d4