[GHC] #7931: Deriving Read of an empty datatype crashes

[GHC]

#7931: Deriving Read of an empty datatype crashes
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Reporter:  monoidal          |          Owner:                  
    Type:  bug               |         Status:  patch           
Priority:  normal            |      Component:  Compiler        
 Version:  7.6.3             |       Keywords:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  None/Unknown      |      Blockedby:                  
Blocking:                    |        Related:                  
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Comment(by monoidal):

 @parcs: What I get is:

 {{{
 g at g-lap:~/haskell/head$ ghc-7.7.20130515 X
 [1 of 1] Compiling Main             ( X.hs, X.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.7.20130515 for x86_64-unknown-linux):
         Prelude.foldr1: empty list

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

 g at g-lap:~/haskell/head$ ghci-7.7.20130515 X
 GHCi, version 7.7.20130515: http://www.haskell.org/ghc/  :? for help
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 [1 of 1] Compiling Main             ( X.hs, interpreted )
 *** Exception: Prelude.foldr1: empty list
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7931#comment:3>
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