Auto merge of #31908 - jseyfried:disallow_shadowed_traits, r=nikomatsakis

Disallow methods from traits that are not in scope

This PR only allows a trait method to be used if the trait is in scope (fixes #31379).
This is a [breaking-change]. For example, the following would break:
```rust
mod foo {
    pub trait T { fn f(&self) {} }
    impl T for () {}
}

mod bar { pub use foo::T; }

fn main() {
    pub use bar::*;
    struct T; // This shadows the trait `T`,
    ().f() // making this an error.
}
```
r? @nikomatsakis

0 files changed, 0 insertions, 0 deletions