rust/src/test/run-pass/expr-alt-fail-all.rs

// When all branches of an alt expression result in fail, the entire
// alt expression results in fail.
fn main() {
    auto x =
        alt (true) {
            case (true) { 10 }
            case (false) {
                alt (true) { case (true) { fail } case (false) { fail } }
            }
        };
}