#12860: GeneralizedNewtypeDeriving + MultiParamTypeClasses sends typechecker into an infinite loop -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Keywords: FunDeps, Resolution: | deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * cc: diatchki (added) Comment: Indeed, I suspect we need a more permissive check than `checkInstCoverage` which would reject `C b a` but not `Monoid w` in the `XMLGenT` example. Alas, I have no idea what that check would be. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12860#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler