#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: | -------------------------------------+------------------------------------- Comment (by dfeuer): Ryan mentions {{{#!hs newtype XMLGenT m a = XMLGenT (m a) deriving (MonadRWS r w s)` }}} I suspect what we want to do is collect the fundeps from the ''superclass constraints'' of `MonadRWS` before doing anything much else. I have the feeling (maybe wrong?) that we can get these more safely than we can fundeps of instance constraints. These should (at least in this case) be sufficient to satisfy the coverage condition. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12860#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler