GHC suggests an out of scope variable in a parallel list comprehension
Summary
When you use a variable from one branch of a parallel list comprehension in another branch, ghc will correctly report it as an out of scope variable but suggest it as an alternative.
Steps to reproduce
ghci> :set -XParallelListComp
ghci> [ (a, b) | a <- [0 ..] | b <- "abcd", even a ]
<interactive>:5:44: error:
• Variable not in scope: a
• Perhaps you meant ‘a’ (line 5)
Expected behavior
It should not suggest the variable that is out of scope.
Environment
- GHC version used: 9.2.5, but also seen in 9.4.4 and 8.10.7
Optional:
- Operating System: Ubuntu 20.04.1
- System Architecture: x86_64