#2394: deriving instance Data (a->b) leads to 'impossible' error instead of
"can't
do" message
------------------------+---------------------------------------------------
Reporter: claus | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.9 | Severity: normal
Keywords: | Testcase:
Architecture: Unknown | Os: Unknown
------------------------+---------------------------------------------------
{{{
$ cat Data.hs
{-# OPTIONS_GHC -fglasgow-exts #-}
import Data.Generics(Data)
deriving instance (Data a,Data b) => Data (a->b)
$ ghc --make Data.hs
[1 of 1] Compiling Main ( Data.hs, Data.o )
Data.hs:4:0:ghc.exe: panic! (the 'impossible' happened)
(GHC version 6.9.20080514 for i386-unknown-mingw32):
newTyConEtadRhs ghc-prim:GHC.Prim.(->){(w) tc 3D}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2394>
GHC <http://www.haskell.org/ghc/>
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