Dear GHC team, I am testing the 7.02 candidate of ghc-7.0.1.20110217 -- compiled from source, compiled by itself, on Debian Linux, i386-family. On my DoCon program, it reports the following. 1. It requires `-fcontext-stack=_' to increase a certain stack: ... [67 of 83] Compiling Pfact__ ( Pfact__.hs, dist/build/Pfact__.o ) [68 of 83] Compiling RsePol_ ( RsePol_.hs, dist/build/RsePol_.o ) RsePol_.hs:214:28: Context reduction stack overflow; size = 21 Use -fcontext-stack=N to increase stack size to N $dSet :: Set (UPol (ResidueE Integer)) $dAddSemigroup :: AddSemigroup (UPol (ResidueE Integer)) $dAddMonoid :: AddMonoid (UPol (ResidueE Integer)) ... $dCast :: Prelude_.Cast (ResidueE (UPol (Pfact__.RseUPolRse Integer))) (UPol (Pfact__.RseUPolRse Integer)) In the first argument of `(.)', namely `ct c1' In the expression: ct c1 . toOverK . resRepr In an equation for `toC': toC = ct c1 . toOverK . resRepr ------------------------------------------- So, I add -fcontext-stack=30 to the ghc-options line in docon.cabal. Which one is better at this point, 7.0.1 or 7.0.1.20110217 ? 2. Then, DoCon is built, and the commands cd demotest ghc $doconCpOpt -O -rtsopts --make Main need to `make' the DoCon test under the DoCon library. This reports [ 1 of 17] Compiling T_detinterp ( T_detinterp.hs, T_detinterp.o ) [ 2 of 17] Compiling T_sphGeo ( T_sphGeo.hs, T_sphGeo.o ) [ 3 of 17] Compiling T_cubeext ( T_cubeext.hs, T_cubeext.o ) T_cubeext.hs:143:9: Overlapping instances for LinSolvRing (UPol k) arising from a use of `ct' Matching instances: instance [overlap ok] EuclideanRing a => LinSolvRing (UPol a) -- Defined in docon-2.12:Pol2_ instance [overlap ok] (LinSolvRing (Pol a), CommutativeRing a) => LinSolvRing (UPol (Pol a)) -- Defined in docon-2.12:Pol3_ (The choice depends on the instantiation of `k' To pick the first instance above, use -XIncoherentInstances when compiling the other instance declarations) In the first argument of `(.)', namely `ct unE' In the expression: ct unE . kToB In an equation for `kToE': kToE = ct unE . kToB -------------------------------------------------------------------- This looks like a bug of the kind appeared in a couple of earlier GHC versions. ghc-7.0.1 is free of both of these effects. What is your opinion about this? http://www.botik.ru/pub/local/Mechveliani/ghcBugs/702candBug.zip is the archive with the project to make and run under ghc-7.0.1, and ghc-7.0.1.20110217 (follow install.txt). Regards, ----------------- Serge Mechveliani mechvel@botik.ru