When I compile/link

{-# LANGUAGE BangPatterns #-}

module Main where

!(Just x) = Nothing

main = putStrLn "hi there!"

I get

rae:09:50:49 ~/temp> ghc Bug.hs
[1 of 1] Compiling Main             ( Bug.hs, Bug.o )
Linking Bug ...
ld: can't open output file for writing: Bug, errno=21 for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
`gcc' failed in phase `Linker'. (Exit code: 1)

This bogus code should be rejected more gracefully (and earlier). It actually also loads into GHCi, but shouldn't.

Will fix while I'm in the area.