Rust Analyzer detects a syntax error when the code compiles and runs just fine

[itsKhalidHossain]

Here is the sample code:

fn collatz(n: u64) -> Option<u64> {
    const OVERFLOW_BARRIER: u64 = u64::MAX / 3;
    let mut n = n;
    for i in 0.. {
        n = match (n, n % 2) {
            (0, _) => break,
            (1, _) => return Some(i),
            (OVERFLOW_BARRIER.., 1) => 0, // <- Errors out here.
            (_, 0) => n / 2,
            _ => n * 3 + 1,
        }
    }
    None
}

Changing OVERFLOW_BARRIER.. to OVERFLOW_BARRIER..=u64::MAX seems to work.

But changing placement of match tuple works just fine:

pub fn collatz(n: u64) -> Option<u64> {
    const OVERFLOW_BARRIER: u64 = u64::MAX / 3;
    let mut n = n;
    for i in 0.. {
        n = match (n % 2, n) {
            (_, 0) => break,
            (_, 1) => return Some(i),
            (1, OVERFLOW_BARRIER..) => 0, // Detects no error.
            (0, _) => n / 2,
            _ => n * 3 + 1,
        }
    }
    None
}

But Rust compiler doesn't detect any error. It compiles just fine.

[Veykril]

I think this was reported before but I can't find where.

[jonas-schievink]

Maybe in #9066?