rust/src/test/mir-opt/issue-41888.rs

// check that we clear the "ADT master drop flag" even when there are
// no fields to be dropped.

// EMIT_MIR rustc.main.ElaborateDrops.after.mir
fn main() {
    let e;
    if cond() {
        e = E::F(K);
        if let E::F(_k) = e {
            // older versions of rustc used to not clear the
            // drop flag for `e` in this path.
        }
    }
}

fn cond() -> bool { false }

struct K;

enum E {
    F(K),
    G(Box<E>)
}