LYR-SEM0146

a 'return' in a function returning 'never'

error · spec 06-errors

A function whose return type is 'never' contains a 'return', other than one returning a call that itself does not return.

Explanation

A function returning never promises that it does not return: every path ends in a panic, a throw, an endless loop, or a call of another never function. A return breaks that promise, and the caller's code after the call would run after all.

End the path with a panic, a throw or a call that does not return, or change the return type.

Wrong

fn stop(): never {
    return;
}

fn main(): void {
    stop();
}

Right

fn stop(): never {
    panic("stopped");
}

fn main(): void {
    stop();
}