Rollup merge of #51952 - petrochenkov:transmark, r=alexcrichton

 hygiene: Decouple transparencies from expansion IDs

And remove fallback to parent modules during resolution of names in scope.

This is a breaking change for users of unstable macros 2.0 (both procedural and declarative), code like this:
```rust
#![feature(decl_macro)]

macro m($S: ident) {
    struct $S;
    mod m {
        type A = $S;
    }
}

fn main() {
    m!(S);
}
```
or equivalent
```rust
#![feature(decl_macro)]

macro m($S: ident) {
    mod m {
        type A = $S;
    }
}

fn main() {
    struct S;
    m!(S);
}
```
stops working due to module boundaries being properly enforced.

For proc macro derives this is still reported as a compatibility warning to give `actix_derive`, `diesel_derives` and `palette_derive` time to fix their issues.

Fixes https://github.com/rust-lang/rust/issues/50504 in accordance with [this comment](https://github.com/rust-lang/rust/issues/50504#issuecomment-399764767).

0 files changed, 0 insertions, 0 deletions