#951: Incorrect error messages for non-existing dependencies ---------------------------------+------------------------------------------ Reporter: guest | Owner: Type: enhancement | Status: new Priority: normal | Milestone: cabal-install-0.16 Component: cabal-install tool | Version: 1.14.0 Severity: normal | Keywords: message, solver Difficulty: unknown | Ghcversion: 7.4.1 Platform: Linux | ---------------------------------+------------------------------------------
Comment(by kosmikus): It's really a question about which error message to choose. If you scan up in your log, you will see another "fail (backjumping ..." line before the one you've just shown. Currently, the solver tries backtracking to a limit, and if it fails, it will print the *first* error it encountered. This is based on the heuristic that usually, the first choices involve the least compromises, and are most likely to point to the actual problem. In this case, it actually points at a real problem (namely "transformers-3" being incompatible with your package), but that's not the main problem you're interested in. I do have something in mind that might fix this. I am planning to use the backtracking solver to generate several install plans and pick a "best" one according to heuristics. We could do the same for error messages. However, it's less clear to me how to define heuristics for what constitutes the best among several error messages. -- Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/951#comment:3> Hackage <http://haskell.org/cabal/> Hackage: Cabal and related projects _______________________________________________ cabal-devel mailing list cabal-devel@haskell.org http://www.haskell.org/mailman/listinfo/cabal-devel