Auto merge of #31105 - jseyfried:fix_lexical_scoping, r=nrc

This fixes #23880, a scoping bug in which items in a block are shadowed by local variables and type parameters that are in scope.

After this PR, an item in a block will shadow any local variables or type parameters above the item in the scope hierarchy. Items in a block will continue to be shadowed by local variables in the same block (even if the item is defined after the local variable).

This is a [breaking-change]. For example, the following code breaks:
```rust
fn foo() {
    let mut f = 1;
    {
        fn f() {}
        f += 1; // This will resolve to the function instead of the local variable
    }
}

0 files changed, 0 insertions, 0 deletions