[GHC] #5884: GHC panics while trying to derive a Generic instance for Complex a

[GHC]

#5884: GHC panics while trying to derive a Generic instance for Complex a
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 Reporter:  mux                 |          Owner:                  
     Type:  bug                 |         Status:  new             
 Priority:  normal              |      Component:  Compiler        
  Version:  7.4.1               |       Keywords:                  
       Os:  Unknown/Multiple    |   Architecture:  Unknown/Multiple
  Failure:  Compile-time crash  |       Testcase:                  
Blockedby:                      |       Blocking:                  
  Related:                      |  
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Comment(by mux):

 I should have said that GHC crashes similarly, since the output I gave
 shows that it was produced using GHCi (the "interpreted" bit). I initially
 thought the two error messages were identical but there's a single letter
 difference: ahY becomes ahZ. For the sake of completeness, here is the
 error I get using ghc --make on the same test case with a dummy main
 function:

 {{{
 [1 of 1] Compiling Main             ( TestCase.hs, TestCase.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for x86_64-unknown-freebsd):
         tcTyVarDetails
     ( a{tv ahZ} [tv] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5884#comment:2>
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