missing-comparison

Flag x == missing / x != missing. missing propagates through ==, so the comparison is always missing no matter what x is, and using it as a condition raises a TypeError. Use ismissing (or the identity test === / !==) instead. The rule reports an unsafe fix rewriting == to === and != to !==: the rewrite turns a missing result into a Bool, which is the intent but is still a change in behavior.

Comparing against missing by value:

if x == missing
    1
end

warning: missing-comparison
 --> example.jl:1:4
  |
1 | if x == missing
  |    ^^^^^^^^^^^^ comparison against `missing` by value is always `missing`; use `ismissing` or `===`
  = help: Replace `==` with `===`