Dear GHC developers, Please, test ghc-7.10.1 on making docon-2.12 http://www.botik.ru/pub/local/Mechveliani/docon/ and running its demotest/Main (see install.txt). docon-2.12 has been tested under ghc-7.8.2, and it has extensions: ... OverlappingInstances in docon.cabal. Making with ghc-7.10.1 issues a warning and advises to set the related pragma individually to each corresponding instance. (1) First, I ignored this warning, and surprisingly, the library has been made. In the build/ subdirectory there are .hi and .o files, and there have newly appeared the "dyn" files: Matr0_.dyn_hi Matr0_.dyn_o Matr0_.hi Matr0_.o ... (I do not know what does it mean "dyn"). Then, > make install reports runghc Setup.hs install --user Installing library in /home/mechvel/docon/2.12/docon/source/inst/lib/x86_64-linux-ghc-7.10.1/docon_99cUeE74HI58Sb9XilYAZ2 Registering docon-2.12.1... Instead of the .a file, ls shows there docon_99cUeE74HI58Sb9XilYAZ2 docon_JzkSttB1MsX3R5AQ1eIgvC Are these names intended? Then I command
cd demotest ghc $doconCpOpt -O -rtsopts --make Main ./Main
It is built and runs. But breaks in the middle with a certain reasonable DoCon error message. The DoCon design is so that choosing a different instance among the overlapping ones may change the algorithm, and the computation cost, but still must produce the same result. It must -- unless DoCon has a bug in some of these instances. (2) All right, I need to set {-# OVERLAPPABLE #-} individually to each instance which may overlap with some other instance in DoCon. There is declared a great number of instances. And it occurs difficult for me to recall now: which instance does overlap with something and which does not (at least they all worked correct in ghc-7.8.2). Well, I can set {-# OVERLAPPABLE #-} to _each_ instance. But such a program does not look nice. And I would like to be more definite and to set {-# OVERLAPPING #-} to all appropriate places. Suppose that I forget that some instance overlaps with something and skipped this pragma. The above test shows that this can lead to a wrong program to run (is this feature intended?). And what will be the consequence if {-# OVERLAPPING #-} is set to an instance which does not overlap with anything? Can the compiler help to list the overlaps? Please, advise, ------ Sergei