Cannot infer type when assigning comptime generic field to a Field.

[iAmMichaelConnor]

The following panics when the annotation : Field is omitted.

fn be_bytes_to_field<LEN>(bytes: [u8; LEN]) -> Field {
    let mut f = 0;
    let mut b = 1;
    let mut len = LEN - 1; // FAILS
    // let mut len: Field = LEN - 1; // SUCCEEDS
    for i in 0..LEN {
        let j = len - i;
        f += (bytes[j] as Field) * b;
        b *= 256;
    }
    f
}

fn main(bytes: [u8; 8]) -> pub Field {
    let f: Field = be_bytes_to_field(bytes);
    f
}

#[test]
fn test_bytes_to_field() {
    let bytes: [u8; 8] = [0, 0, 0, 0, 0, 1, 3, 1];
    let f = main(bytes);
    std::println(f);
}

Running 1 test functions...
Testing test_bytes_to_field...
The application panicked (crashed).
Message:  internal error: entered unreachable code: Unexpected type error found
Location: crates/noirc_frontend/src/monomorphization/mod.rs:736

This is a bug. We may have already fixed this in newer versions of Nargo so try searching for similar issues at https://github.com/noir-lang/noir/issues/.
If there isn't an open issue for this bug, consider opening one at https://github.com/noir-lang/noir/issues/new?labels=bug&template=bug_report.yml

Using latest Noir master, commit 4ecf3c4.

nargo test --show-output