Labels scoped too highly

[evanrichter]

Hello, I believe I found a bug in how labels are defined to a scope. The same text abcd defines two distinct labels, each inside an anonymous scope using { ... }.

I tried this code:

fn main() {
    {
        'abcd: loop {
            break 'abcd;
        }
    }
    {
        'abcd: loop {
            break 'abcd;
        }
    }
}

(Playground)

Errors:

   Compiling playground v0.0.1 (/playground)
warning: label name `'abcd` shadows a label name that is already in scope
 --> src/main.rs:8:9
  |
3 |         'abcd: loop {
  |         ----- first declared here
...
8 |         'abcd: loop {
  |         ^^^^^ lifetime 'abcd already in scope

warning: 1 warning emitted

    Finished dev [unoptimized + debuginfo] target(s) in 0.42s
     Running `target/debug/playground`

I expected to see this happen: code compiles

Instead, this happened: labels are identified as the same, but they actually have different scopes

Meta

This appears to happen on both nightly and stable.

[abnormalmaps]

This seems to be intentional, as indicated by tests for this situation in src/test/compile-fail/loops-reject-duplicate-labels-2.rs, but I think it would be nice if there was someone else to discuss this with.

(also see #21633)

[jonas-schievink]

Yeah, this is working as intended. Feel free to discuss this on https://internals.rust-lang.org/ though.