Rollup merge of #157215 - JonathanBrouwer:repr-target-checking3, r=mejrs

Implement argument-dependent target checking for the `#[repr]` parser

Fixes some of rust-lang/rust#156499
Fixes some of rust-lang/rust#153101
Alternative approach to rust-lang/rust#156569, which was suggested in the comments here: rust-lang/rust#156569 (review)

How do you feel about this approach?
r? @mejrs

Author: JonathanBrouwer