Compiler hangs when reading interface file

Jeroen Weijers reports: I have two files Data.hs and Class.hs (Class depends on Data). When I compile Class.hs (ghc --make Class.hs) the ghc does what it should do. When I now make a change to Class.hs (add a newline to the end of the file for example) and try to run ghc --make Class.hs again the ghc gets stuck on recompiling Class.hs.

module Class where
  import Data
  foo :: Exp a
  foo = error "urk"

{-# LANGUAGE GADTs #-}
module Data where
  data Exp a where
     LamE :: (Exp a -> Exp b) -> Exp (Exp a -> Exp b)

Trac metadata

Trac field	Value
Version	7.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	jeroenweijers@gmail.com
Operating system
Architecture