rust/tests/mir-opt/dest-prop/union.rs

// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
//! Tests that we can propagate into places that are projections into unions
//@ compile-flags: -Zunsound-mir-opts -C debuginfo=full
fn val() -> u32 {
    1
}

// EMIT_MIR union.main.DestinationPropagation.diff
fn main() {
    // CHECK-LABEL: fn main(
    // CHECK: {{_.*}} = Un { us: const 1_u32 };
    union Un {
        us: u32,
    }

    let un = Un { us: val() };

    drop(unsafe { un.us });
}