Static rustc_lint_defs::builtin::BREAK_WITH_LABEL_AND_LOOP

pub static BREAK_WITH_LABEL_AND_LOOP: &'static Lint

The break_with_label_and_loop lint detects labeled break expressions with an unlabeled loop as their value expression.

Example

'label: loop {
    break 'label loop { break 42; };
};

{{produces}}

Explanation

In Rust, loops can have a label, and break expressions can refer to that label to break out of specific loops (and not necessarily the innermost one). break expressions can also carry a value expression, which can be another loop. A labeled break with an unlabeled loop as its value expression is easy to confuse with an unlabeled break with a labeled loop and is thus discouraged (but allowed for compatibility); use parentheses around the loop expression to silence this warning. Unlabeled break expressions with labeled loops yield a hard error, which can also be silenced by wrapping the expression in parentheses.