LYR-PAR0065

a 'continue', 'break' or 'return' where a value stands

error · spec 16-diagnostics

A jump stands where an expression is wanted — a match arm, a branch of an if expression —; it is a statement and goes in a block, => { continue; }.

Explanation

continue, break and return are statements: they leave, and give no value. Where an arm of a match or a branch of an if expression wants a value, a block holds the statement, and a block that leaves is worth never, which fits any arm. The compiler reads the jump as that block and checks the other arms as usual.

lyric fix writes the block: ' ' => continue, becomes ' ' => { continue; },.

Wrong

fn main(): void {
    for (c in "a b".chars()) {
        let n = match (c) {
            ' ' => continue,
            _ => 1,
        };
        let _ = n;
    }
}

Right

fn main(): void {
    for (c in "a b".chars()) {
        let n = match (c) {
            ' ' => { continue; },
            _ => 1,
        };
        let _ = n;
    }
}