#8129: Constraint solver panic due to derived type function equality --------------------------------------------+------------------------------ Reporter: adamgundry | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler (Type checker) | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:8cfbdccb7f8716c2b6b13b3c7884f52b1087d782/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="8cfbdccb7f8716c2b6b13b3c7884f52b1087d782" Accommodate Derived constraints in two places (fix Trac #8129, #8134) If we have class (F a ~ b) => C a b then we can produce *derived* CFunEqCans. These were not being treated properly in two places: a) in TcMType.zonkFlats (Trac #8134) b) in TcSMonad.prepareInertsForImplications (Trac #8129) This patch fixes both. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8129#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler