Gccrs gets confused by mutable reference binding in match expressions

[liamnaddell]

Summary

I was trying to take a look at constexpr folding, and came across this bug. This seems to be due to a lack of ref mut support, i.e. #2082 's TODO list.

Rustc compiles this code happily

Reproducer

I tried this code:

extern "C" {
    fn printf(s: *const i8, ...);
}

enum Option {
    Some(i32), None
}

impl Option {
    fn add(&mut self) {
        match *self {
            Option::Some(ref mut a) => {*a += 1},
            Option::None => {},
        }
    }
}

fn main() {
    unsafe {
        let mut a = Option::None;
        a.add();
        let _s = "%d\n\0";
        let _s = _s as *const str;
        let s = _s as *const i8;
        printf(s,a);
    }
}

Does the code make use of any (1.49) nightly feature ?

• Nightly

Godbolt link

No response

Actual behavior

The current behavior is...

main.rs:12:41: error: expected reference type got i32
   12 |             Option::Some(ref mut a) => {*a += 1},
      |                                         ^
main.rs:12:41: error: cannot apply operator ‘+=’ to types <tyty::error> and <integer>

Expected behavior

Rustc compiles the code

GCC Version

483ee3a