Regression in match patterns in beta

[Razican]

Hello, the pattern matching in match arms seems to have different behavior in stable than in beta/nightly.

I tried this code:

use std::i8;

fn main() {
    let a = Some(-50_i8);
    match a {
        Some(c @ i8::MIN...-101) | Some(c @ 101...i8::MAX) => println!("out of bounds, {}", c),
        _ => println!("OK"),
    }
}

I expected to see this happen: In all chains, it should print "OK".

Instead, this happened: It prints "OK" in stable, but it prints "out of bounds, -50" in beta/nightly.

Example in the playground

I understand that this code is not very idiomatic, but still, I think that the behavior should be consistent between Rust versions.

[Centril]

Reduced:

fn main() {
    assert_eq!(false, match -50_i8 { -128i8...-101i8 => true, _ => false, });
}

// also with if-let:
fn main() {
    assert_eq!(false, if let -128i8...-101i8 = -50_i8 { true } else { false });
}

cc @varkor

[jonas-schievink]

Introduced between nightly-2018-12-14 and nightly-2018-12-15, resp.

rustc 1.32.0-nightly (f4a421ee3 2018-12-13)

rustc 1.33.0-nightly (96d1334e5 2018-12-14)

Commits between those nightlies - indeed looks like #56695 is suspicious

[varkor]

#56695 does look like the culprit. I'll try to fix this tomorrow. Thanks @jonas-schievink!

[pnkfelix]

triage: P-high. Assigned to @varkor