Addressing rust-lang#103894 (comment)

…rity, r=eholk

Check generics parity before collecting return-position `impl Trait`s in trait

The only thing is that this duplicates the error message for number of generics mismatch, but we already deduplicate that error message in Cargo. I could add a flag to delay the error if the reviewer cares.

Fixes rust-lang#104281

Also drive-by adds a few comments to the `collect_trait_impl_trait_tys` method, and removes an unused argument from `compare_number_of_generics`.

…md64, r=thomcc

Reduce exceptions overallocation on non Windows x86_64

Addressing rust-lang#103894 (comment)

…lowering, r=compiler-errors

Create def_id for async fns during lowering

r? `@compiler-errors`

…-bindings, r=cjgillot

Only declare bindings for if-let guards once per arm

Currently, each candidate for a match arm uses separate locals for the bindings in the if-let guard, causing problems (rust-lang#88015) when those branches converge in the arm body.

Fixes rust-lang#88015 (🤞)

…pty-hack, r=TaKO8Ki

Remove a lifetime resolution hack from `compare_predicate_entailment`

This is not needed anymore, probably due to rust-lang#102334 equating the function signatures fully in `collect_trait_impl_trait_tys`. Also, the assertion in in rust-lang#102903 makes sure that this is actually fixed, so I'm pretty confident this isn't needed.

…thomcc

disable strict-provenance-violating doctests in Miri

Most of these are on deprecated unstable functions anyway. This lets us run the remaining doctests with `-Zmiri-strict-provenance`, which I think is a win.

r? `@thomcc`