Add hint for collect type

[Mark-Simulacrum]

This should hopefully fix rust-lang/rust#72054 (comment) I have not yet had a chance to run tests locally though (I believe this should fix the remaining problem though).

I guess in the future we'll fix this upstream but this beta cycle we can't do that unfortunately :/

changelog: none

[Mark-Simulacrum]

I think CI failure is because it's testing against master rustc?

r? @flip1995

[flip1995]

Yes, we didn't set up our CI for the beta branch (yet). I'll take a look at it in about an hour and merge it by hand.

[flip1995]

I think the second error:

error[E0277]: `std::vec::Vec<rustc_middle::ty::Predicate<'_>>` is not an iterator
   --> src/tools/clippy/clippy_lints/src/needless_pass_by_value.rs:114:58
    |
114 |         let preds = traits::elaborate_predicates(cx.tcx, cx.param_env.caller_bounds.to_vec())
    |                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `std::vec::Vec<rustc_middle::ty::Predicate<'_>>` is not an iterator
    |
    = help: the trait `std::iter::Iterator` is not implemented for `std::vec::Vec<rustc_middle::ty::Predicate<'_>>

should also be addressed here. I currently am compiling the rust PR to test this PR.

[Mark-Simulacrum]

I think I managed to address that upstream -- the PR on rust-lang/rust master changed that function to take impl Iterator but I changed it back to impl IntoIterator, there's not really a reason to force callers to .into_iter() on their side.

[flip1995]

Sorry for taking so long, had to compile LLVM... Local tests looked good.

I directly merged it in the beta branch, instead of branching it beforehand, since it will land in rustc beta branch anyway.

@Mark-Simulacrum please use commit d4092ac for the submodule update.