"derive instance" panics ghc-6.7.20070404
I've been happy to see the support for "dervice instance". In the past I've had to make a copy of parsec, just to dervice Data and Typeable for the Pos type in order to do SYB on my AST.
Unfortunately "dervive instance" panics the 6.7 compiler at the moment (I need/want 6.7 since the -fhpc support rocks!).
> import Text.ParserCombinators.Parsec.Pos as PPos
> ...
> derive instance Data PPos.SourcePos
This produces:
TLACodeGen.hs:485:0:ghc-6.7.20070404: panic! (the 'impossible' happened)
(GHC version 6.7.20070404 for powerpc-apple-darwin):
newTyConRhs
main:Text.ParserCombinators.Parsec.Pos.SourcePos{tc r1R}
Details of my system:
yoghurt:~/sdev/specifica/australis reto$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.7.20070404
yoghurt:~/sdev/specifica/australis reto$ uname -a
Darwin yoghurt.local 8.8.0 Darwin Kernel Version 8.8.0: Fri Sep 8 17:18:57 PDT 2006; root:xnu-792.12.6.obj~1/RELEASE_PPC Power Macintosh powerpc
yoghurt:~/sdev/specifica/australis reto$ gcc -v
Reading specs from /usr/lib/gcc/powerpc-apple-darwin8/4.0.0/specs
Configured with: /private/var/tmp/gcc/gcc-4061.obj~8/src/configure --disable-checking --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^+.-]*$/s/$/-4.0/ --with-gxx-include-dir=/include/gcc/darwin/4.0/c++ --build=powerpc-apple-darwin8 --host=powerpc-apple-darwin8 --target=powerpc-apple-darwin8
Thread model: posix
gcc version 4.0.0 20041026 (Apple Computer, Inc. build 4061)