the 'impossible' happened

$ cat bug.hs 
foo = do let bad = [True | x <- [] | y <- []]
$ ghc bug.hs 
[1 of 1] Compiling Main             ( bug.hs, bug.o )

bug.hs:1:10:ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for x86_64-apple-darwin):
	Prelude.undefined

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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