Bug in compiling large projects ?

[Simon Peyton-Jones]

I've not had time to look at this yet.  It does seem odd.
I'll get to it. Meanwhile, it's not a show-stopper for you, is it?

Simon

| -----Original Message-----
| From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-users-
| bounces at haskell.org] On Behalf Of Klaus Lüttich
| Sent: 25 August 2004 12:02
| To: glasgow-haskell-users at haskell.org
| Cc: glasgow-haskell-bugs at haskell.org
| Subject: Bug in compiling large projects ?
| 
| Hello,
| 
| I have send a message to these lists a weak ago with almost the same
| topic, but I have now additional observations: The problem is not
| related to option -O in GHC 6.2.1 ! We use in conjunction these command
| line switches for the compilation:
|   --make -fglasgow-exts -fallow-overlapping-instances
|   -fallow-undecidable-instances
| 
| and get this error message, when we try to compile the complete project:
| 
| Compiling Common.Lib.Rel   ( ./Common/Lib/Rel.hs, ./Common/Lib/Rel.o )
| 
| ./Common/Lib/Rel.hs:102:
|     Could not unambiguously deduce (Show (a, a))
| 	from the context (Show (Rel a), Show a, Ord a)
|       arising from use of `show' at ./Common/Lib/Rel.hs:102
|     The choice of (overlapping) instance declaration
| 	depends on the instantiation of `a'
|     Probable fix:
| 	Add (Show (a, a)) to the class or instance method `show'
| 	Or add an instance declaration for (Show (a, a))
|     In the first argument of `(.)', namely `show'
|     In the definition of `show':
| 	show = show . (Common.Lib.Set.fromList . toList)
|     In the definition for method `show'
| 
| When we issue the same ghc call again, Common/Lib/Rel is compiled
| without errors.
| Well, the needed tar-ball (4.2M) to reproduce the error is downloadable
| at
| http://www.informatik.uni-bremen.de/agbkb/forschung/formal_methods/CoFI/hets/hets-src.tgz
| 
| Cheers,
| 	Klaus
| --
| Klaus Lüttich    Email:   luettich at tzi.de
| FB 3             Phone:   +49-421-218-7129
| Uni Bremen
| _______________________________________________
| Glasgow-haskell-users mailing list
| Glasgow-haskell-users at haskell.org
| http://www.haskell.org/mailman/listinfo/glasgow-haskell-users