Bug in compiling large projects ?
luettich at tzi.de
Wed Aug 25 07:01:41 EDT 2004
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
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 )
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'
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
Well, the needed tar-ball (4.2M) to reproduce the error is downloadable
Klaus Lüttich Email: luettich at tzi.de
FB 3 Phone: +49-421-218-7129
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