[GHC] #6025: GHC Panic On Recompile

[GHC]

#6025: GHC Panic On Recompile
---------------------------------+------------------------------------------
    Reporter:  scooty-puff       |       Owner:                    
        Type:  bug               |      Status:  new               
    Priority:  normal            |   Milestone:                    
   Component:  Compiler          |     Version:  7.4.1             
    Keywords:                    |          Os:  Unknown/Multiple  
Architecture:  Unknown/Multiple  |     Failure:  Compile-time crash
  Difficulty:  Unknown           |    Testcase:                    
   Blockedby:                    |    Blocking:                    
     Related:                    |  
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Comment(by scooty-puff):

 Other.hs:
 {{{
 {-# LANGUAGE DataKinds, GADTs #-}
 module Other (Other (..)) where

 data Other a where
   OTrue :: Other True
   OFalse :: Other False
 }}}

 It can probably also be recreated using KindSignatures, but I have not
 attempted this.

 Main.hs:
 {{{
 module Main (main) where

 import Other

 other = OTrue

 main :: IO ()
 main = return ()
 }}}

 To recreate:
 {{{
 ghc --make Main.hs
 touch Main.hs
 ghc --make Main.hs
 }}}

 Output:
 {{{
 $ ghc --make Main.hs
 [2 of 2] Compiling Main             ( Main.hs, Main.o )
 ghc.exe: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for i386-unknown-mingw32):
         tyThingTyCon Data constructor `ghc-prim:GHC.Types.True{(w) d 6u}'

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

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6025#comment:3>
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