[GHC] #5513: panic! (the 'impossible' happened) on ‘deriving instance lowercase_name a’

[GHC]

#5513: panic! (the 'impossible' happened) on ‘deriving instance lowercase_name a’
---------------------------------+------------------------------------------
    Reporter:  andersk           |       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
---------------------------------+------------------------------------------
 This bogus code:
 {{{
 {-# LANGUAGE StandaloneDeriving #-}
 deriving instance lowercase_name a
 }}}
 causes current GHC HEAD to panic:
 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.3.20110927 for x86_64-unknown-linux):
         nameModule lowercase_name{tv aar}

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

 I also tested GHC 7.0.3, which correctly diagnosed the problem:
 {{{
 crash.hs:2:19: Malformed instance header: lowercase_name a
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5513>
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