// run-pass
// This used to segfault #30081

pub enum Instruction {
    Increment(i8),
    Loop(Box<Box<()>>),
}

fn main() {
    let instrs: Option<(u8, Box<Instruction>)> = None;
    instrs.into_iter()
        .map(|(_, instr)| instr)
        .map(|instr| match *instr { _other => {} })
        .last();
}