rust/src/test/mir-opt/match-arm-scopes.rs

// ignore-wasm32-bare compiled with panic=abort by default
// Test that StorageDead and Drops are generated properly for bindings in
// matches:
// * The MIR should only contain a single drop of `s` and `t`: at the end
//   of their respective arms.
// * StorageDead and StorageLive statements are correctly matched up on
//   non-unwind paths.
// * The visibility scopes of the match arms should be disjoint, and contain.
//   all of the bindings for that scope.
// * No drop flags are used.

// EMIT_MIR rustc.complicated_match.SimplifyCfg-initial.after.mir
// EMIT_MIR rustc.complicated_match.ElaborateDrops.after.mir
fn complicated_match(cond: bool, items: (bool, bool, String)) -> i32 {
    match items {
        (false, a, s) | (a, false, s) if if cond { return 3 } else { a } => 1,
        (true, b, t) | (false, b, t) => 2,
    }
}

const CASES: &[(bool, bool, bool, i32)] = &[
    (false, false, false, 2),
    (false, false, true, 1),
    (false, true, false, 1),
    (false, true, true, 2),
    (true, false, false, 3),
    (true, false, true, 3),
    (true, true, false, 3),
    (true, true, true, 2),
];

fn main() {
    for &(cond, items_1, items_2, result) in CASES {
        assert_eq!(complicated_match(cond, (items_1, items_2, String::new())), result,);
    }
}