This is consistent with normal match guards.

…t constants

clarify safety documentation of ptr::swap and ptr::copy

Closes rust-lang#81005

…, r=cjgillot

Make if let guard parsing consistent with normal guards

- Add tests that struct expressions are not allowed in `if let` and `while let` (no change, consistent with `if` and `while`)
- Allow struct expressions in `if let` guards (consistent with `if` guards).

r? `@cjgillot`

Closes rust-lang#93817
cc rust-lang#51114

…rors

Implement SMIR generic parameter instantiation

Also demonstrates the use of it with a test.

This required a few smaller changes that may conflict with `@ericmarkmartin` work, but should be easy to resolve any conflicts on my end if their stuff lands first.

… r=aliemjay

implied bounds: do not ICE on unconstrained region vars

fixes rust-lang#112832

see tests/ui/implied-bounds/implied-bounds-unconstrained-2.rs for a minimal example showing why this is necessary.

r? types

cc `@compiler-errors` `@aliemjay` https://rust-lang.zulipchat.com/#narrow/stream/144729-t-types/topic/assoc.20type.20bound.20in.20super.20trait

Make Voldemort comments less cryptic

These comments stumbled me when I saw them and had to ask what they meant, so I changed them to be less cryptic.

r? `@davidtwco`