[GHC] #5439: Crash in TcEnv.lhs line 461

[GHC]

#5439: Crash in TcEnv.lhs line 461
-----------------------------------+----------------------------------------
    Reporter:  mikhail.vorozhtsov  |       Owner:                    
        Type:  bug                 |      Status:  new               
    Priority:  normal              |   Component:  Compiler          
     Version:  7.3                 |    Keywords:                    
    Testcase:                      |   Blockedby:                    
          Os:  Unknown/Multiple    |    Blocking:                    
Architecture:  Unknown/Multiple    |     Failure:  Compile-time crash
-----------------------------------+----------------------------------------
 The attached program makes GHC panic:
 {{{
 $ ghc-7.3.20110828 -fforce-recomp Bug.hs
 [1 of 1] Compiling Main             ( Bug.hs, Bug.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.3.20110828 for x86_64-unknown-linux):
         ASSERT failed! file compiler/typecheck/TcEnv.lhs line 461
 register{v amY} [lid]
 forall n{tv amZ} [tv].
 main:Main.HDropClass{tc r18} n{tv amZ} [tv] rs{tv amV} [ssk] =>
 ghc-prim:GHC.Types.Bool{(w) tc 3c}
 -> main:Main.Peano{tc ru} n{tv amZ} [tv]
 -> main:Main.WaitOps{tc ro}
      (main:Main.HDrop{tc r17} n{tv amZ} [tv] rs{tv amV} [ssk])
 -> ghc-prim:GHC.Types.IO{tc 32I} ghc-prim:GHC.Types.Bool{(w) tc 3c}

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

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5439>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler