Segfault when matching on enums

[justinj]

This code (playground link) gives me a segfault on the current beta:

#[derive(Clone, Copy)]
enum Bar {
    C
}

#[derive(Clone, Copy)]
enum Foo {
    A {},
    B {
        y: f64,
        z: Bar
    },
}

fn f(s: &Foo) {
    match s {
        &Foo::A {} => {
        },
        &Foo::B { y: _y, z: ref _side } => {
        }
    }
}

const LIST: [(usize, Foo); 2] = [
    (51, Foo::B {
        y: 0.,
        z: Bar::C
    }),
    (52, Foo::B {
        y: 0.,
        z: Bar::C
    }),
];

pub fn main() {
    for &r in LIST.iter() {
        let (i, s) = r;
        println!("{}", i);
        f(&s);
    }
}

I've reduced it as much as I can, even removing the A constructor on the enum causes it to work.

I expect the output to be

51
52

(which it is on stable),
but instead I get

51
0
<segfault>

[sfackler]

Appears to be broken on nightly as well - I get a stack overflow on x86_64 darwin.

[frewsxcv]

FWIW, I don't get a segfault on beta or nightly with the playpen, I just get this output for both:

51
0

[TimNN]

The stackoverflow on x86_64 darwin goes away for me on any -C opt-level>0.

[TimNN]

This strongly reminds me of #37222 and #36401.