[GHC] #906: "the `impossible' happened: Maybe.fromJust: Nothing" when using {-# SOURCE #-}

[GHC]

#906: "the `impossible' happened: Maybe.fromJust: Nothing" when using {-# SOURCE
#-}
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  Reporter:  Misha Aizatulin <avatar at hot.ee>  |          Owner:       
      Type:  bug                              |         Status:  new  
  Priority:  normal                           |      Milestone:       
 Component:  Compiler                         |        Version:  6.4.2
  Severity:  normal                           |     Resolution:       
  Keywords:                                   |             Os:  Linux
Difficulty:  Unknown                          |   Architecture:  x86  
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Comment (by simonpj):

 We know what is going on here; module A is being compiled before A.hs-
 boot, so when the latter is compiled it overwrites the in-memory record of
 the object code of A.

 Solution: add edge from A.hs-boot to A.hs.  This is a Good Thing anyway,
 because A.hs-boot should not depend on A.hs (i.e. adding the edge prevents
 another odd case).  But adding the edge also means that A.hs-boot will
 never overwrite A.hs in the HPT.


 Guaranteeing such a message is a bit more work.  See Task #914

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/906>
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