[GHC] #7355: panic when bang is misplaced: tc_hs_type: bang

[GHC]

#7355: panic when bang is misplaced: tc_hs_type: bang
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 Reporter:  elaforge            |          Owner:                  
     Type:  bug                 |         Status:  new             
 Priority:  normal              |      Component:  Compiler        
  Version:  7.6.1               |       Keywords:                  
       Os:  Unknown/Multiple    |   Architecture:  Unknown/Multiple
  Failure:  Compile-time crash  |       Testcase:                  
Blockedby:                      |       Blocking:                  
  Related:                      |  
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 The following file makes ghc panic:

 % cat t.hs

 newtype Scale = Scale (!Maybe Int)

 % ghc -c t.hs

 ghc: panic! (the 'impossible' happened)
   (GHC version 7.6.1 for x86_64-apple-darwin):
         tc_hs_type: bang

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


 I should have written 'Scale (!(Maybe Int))', but ghc should tell me so
 instead of crashing.
 Actually, come to think of it, why isn't '!Maybe Int' valid if it has no
 possible interpretation other than '!(Maybe Int)'?

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7355>
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