E0571 - Error codes index
Description: Book listing all Rust error codes

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# Error code E0571

A `break` statement with an argument appeared in a non-`loop` loop.

Example of erroneous code:

    #![allow(unused)]
    fn main() {
    let mut i = 1;
    fn satisfied(n: usize) -> bool { n % 23 == 0 }
    let result = while true {
        if satisfied(i) {
            break 2 * i; // error: `break` with value from a `while` loop
        }
        i += 1;
    };
    }

The `break` statement can take an argument (which will be the value of the loop expression if the `break` statement is executed) in `loop` loops, but not `for`, `while`, or `while let` loops.

Make sure `break value;` statements only occur in `loop` loops:

    #![allow(unused)]
    fn main() {
    let mut i = 1;
    fn satisfied(n: usize) -> bool { n % 23 == 0 }
    let result = loop { // This is now a "loop" loop.
        if satisfied(i) {
            break 2 * i; // ok!
        }
        i += 1;
    };
    }