src/test/ui/rfc-2008-non-exhaustive/borrowck-non-exhaustive.rs

// Test that the borrow checker considers `#[non_exhaustive]` when checking
// whether a match contains a discriminant read.

// aux-build:monovariants.rs
extern crate monovariants;

use monovariants::NonExhaustiveMonovariant;

fn main() {
    let mut x = NonExhaustiveMonovariant::Variant(1);
    let y = &mut x;
    match x {
        NonExhaustiveMonovariant::Variant(_) => {},
        //~^ ERROR cannot use `x` because it was mutably borrowed
        _ => {},
    }
    drop(y);
}