ghc-6.4.20050220: panic! eval_data2tag...

[Christian Maeder]

This happens when partially recompiling with "-O" (I thing I've send a 
similar bug-report that was kept in the moderator's queue because it was 
to slightly too large - over 40K )

Christian

Thomas Hallgren wrote:
> Hi,
> 
> I managed to distill my program into to the following small example that 
> still exhibits the problem:
> 
>    module Bug where
>    data S e = A | B | C | D | E | F | G | H | I deriving (Eq)
>    newtype R = T (S R) deriving (Eq)
> 
> The output from 'ghc -c -O Bug.hs' is:
> 
> ghc-6.4.20050220: panic! (the `impossible' happened, GHC version 
> 6.4.20050220):
>        eval_data2tag
>    GHCziPrim.dataToTagzh{(w) v 95f}
>      @ (Bug.S{tc r14v} <recnt>Bug.R{tc r14r})
>      (__coerce (Bug.S{tc r14v} <recnt>Bug.R{tc r14r}) a{v s1Cm})
> 
> Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org,
> or http://sourceforge.net/projects/ghc/.
>