Unexpected shadow label warning

[ghost]

This code produces the warning:

fn main() {
    if true {
        'a: loop {
            break 'a;
        }
    } else {
        'a: loop {
            break 'a;
        }
    }
}

Playground link.

[ehuss]

I believe this is intended behavior, see #21633 and https://internals.rust-lang.org/t/psa-rejecting-duplicate-loop-labels/1833.

I think the warning should be converted to a future-compatible lint if the lang team really wants to keep it.

[ghost]

The label isn't in the same scope and there isn't a way to disable/#[allow(...)] this warning. Plus this is accepted by the compiler.

[ehuss]

I think the intent is to make the entire function one scope, instead of using block scopes. You are correct that there isn't a way to allow it, and that should be fixed (this warning was added pre-1.0, a lot has changed since then).

[Nicholas-Baron]

@rustbot label: +A-diagnostics +A-lint.

[ehuss]

Closing as a duplicate of #31745.