Bug report.

Simon Marlow simonmar at microsoft.com
Thu Mar 25 11:40:17 EST 2004

> Started getting:
> ghc- panic! (the `impossible' happened, GHC 
> version
>         mkTyVar a1 {- tv a75q -}
> Please report it as a compiler bug to 
> glasgow-haskell-bugs at haskell.org,
> or http://sourceforge.net/projects/ghc/.
> today... definitely a but to do with class inference, as it 
> started appearing
> aftyer changing some instance constraints and fundeps on classes.
> Can't really be a lot more specific as code is big. Let me 
> know if you want
> me to produce a small code extract which triggers it.

Could you send us enough code to reproduce the bug?  The smaller the
better, but don't worry if you can't reduce it.


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