ghc-6.4.20050220: panic! eval_data2tag...

[Simon Peyton-Jones]

Thanks very much for boiling it down.  The data2tag primop is a dark
corner, I'm afraid.   

Now fixed, and a test added (cg056)

Simon

| -----Original Message-----
| From: Thomas Hallgren [mailto:hallgren at cse.ogi.edu]
| Sent: 22 February 2005 23:20
| To: Simon Marlow; Simon Peyton-Jones
| Cc: glasgow-haskell-bugs at haskell.org
| Subject: Re: ghc-6.4.20050220: panic! eval_data2tag...
| 
| 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/.
| 
| --
| Thomas Hallgren