Comparison of a value that is never None with None

Built from the repository at commit a8614dc.

Only an optional can be None. Comparing a value of another type with None has a fixed answer, so Sisu reports it.

Why

A comparison that can only come out one way is a sign that the type is not what the writer thinks. Either the value should be optional, or the comparison should go.

Broken

fn main() {
    let n = 5
    print(n == None)
}

What sisu says

error[E0044]: `n` is not optional, so it is never `None`
 --> E0044.sisu:3:11
  |
3 |     print(n == None)
  |           ^^^^^^^^^

sisu: 1 error
sisu: for more on a code, run `sisu explain <code>`: E0044

Fixed

fn main() {
    let n: i64? = 5
    print(n == None)
}