#15290: QuantifiedConstraints: panic "addTcEvBind NoEvBindsVar" -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Simpler test case: {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving, StandaloneDeriving, QuantifiedConstraints #-} module Bug where import Data.Coerce class C m where join :: m (m a) -> m a newtype T m a = MkT (m a) deriving instance (C m, forall p q. Coercible p q => Coercible (m p) (m q)) => C (T m) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15290#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler