GHC bug

[Sigbjorn Finne]

Hi,

the bug fixer may have contacted you separately, but for
the benefit of the mailing list and/or you, this one has now
been fixed (i.e., deriving empty datatypes is not permitted).
Thanks for reporting it.

--sigbjorn

----- Original Message ----- 
From: "Hal Daume III" <hdaume at ISI.EDU>
To: <glasgow-haskell-bugs at haskell.org>
Sent: Friday, November 30, 2001 09:24
Subject: GHC bug


> Prelude> :reload 
> Compiling XBar             ( /nfs/isd/hdaume/projects/XBar/XBar.hs,
> interpreted )
> ghc-5.02.1: panic! (the `impossible' happened, GHC version 5.02.1):
> TcGenDeriv:mk_FunMonoBind
> 
> Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org,
> or http://sourceforge.net/projects/ghc/.
> 
> This happened immediately after I change line 35 in the attached program
> from:
> 
>   data DummyHead
> 
> to
> 
>   data DummyHead deriving (Show, Eq)
> 
> I wasn't sure whether it would allow me to derive instances on a datatype
> with no constructors...I know this was recently added and I guess all the
> bugs haven't been worked out.  I'm using the solaris build of ghc.
> 
> --
> Hal Daume III
> 
>  "Computer science is no more about computers    | hdaume at isi.edu
>   than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume
>