#9267: Lack of type information in GHC error messages when the liberage coverage condition is unsatisfied -------------------------------------+------------------------------------- Reporter: danilo2 | Owner: Type: bug | Status: new Priority: high | Milestone: 7.10.1 Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Differential Revisions: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Comment (by simonpj): Interesting example. See all the discussion on #8634. The interesting thing here is that (using the vocabulary of #8634) * The initial error message might suggest `-XDysFunctionalDepenencies` * Adding `-XDysFunctionalDependencies` would yield the error in GHC 7.6 * Adding the suggested context to the instance declaration would remove the need for `-XDysFunctionalDependencies` again! If we implement the `DYSFUNCTIONAL` thing on a per-instance basis, as #8634 suggests, we should also warn when it is used but is not necessary. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9267#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler