The 'impossible happened' compiling with -fext-core

This is what happened:

MrLemao :: Haskell/advanced-track/exercises ‹master*› » ghc --make -O ParTest0.hs -fext-core                  
[1 of 1] Compiling Main             ( ParTest0.hs, ParTest0.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-apple-darwin):
	MkExternalCore died: make_lit

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Trac metadata

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