src/test/ui/borrowck/borrowck-migrate-to-nll.rs


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// This is a test of the borrowck migrate mode. It leverages #27282, a
// bug that is fixed by NLL: this code is (unsoundly) accepted by
// AST-borrowck, but is correctly rejected by the NLL borrowck.
//
// Therefore, for backwards-compatiblity, under borrowck=migrate the
// NLL checks will be emitted as *warnings*.

// NLL mode makes this compile-fail; we cannot currently encode a
// test that is run-pass or compile-fail based on compare-mode. So
// just ignore it instead:

// ignore-compare-mode-nll
// ignore-compare-mode-polonius

// revisions: zflag edition
//[zflag]compile-flags: -Z borrowck=migrate
//[edition]edition:2018
//[zflag] run-pass
//[edition] run-pass

fn main() {
    match Some(&4) {
        None => {},
        ref mut foo
            if {
                (|| { let bar = foo; bar.take() })();
                false
            } => {},
        Some(ref _s) => println!("Note this arm is bogus; the `Some` became `None` in the guard."),
        _ => println!("Here is some supposedly unreachable code."),
    }
}