#12860: GeneralizedNewtypeDeriving + MultiParamTypeClasses sends typechecker into an infinite loop -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: 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 Simon Peyton Jones <simonpj@…>): In [changeset:"f8c966c70bf4e6ca7482658d4eaca2dae367213f/ghc" f8c966c/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="f8c966c70bf4e6ca7482658d4eaca2dae367213f" Be a bit more selective about improvement This patch makes [W] constraints not participate in improvement. See Note [Do not do improvement for WOnly] in TcSMonad. Removes some senseless work duplication in some cases (notably Trac #12860); should not change behaviour. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12860#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler