#11732: Deriving Generic1 interacts poorly with TypeInType -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType, | Generics Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #5939 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * related: => #5939 Comment: OK, it sounds like we're converging on a consensus of being ultra- permissive in allowing GHC to unify visible type parameters when deriving instances. With that in mind, here's what we still need to do to fix this ticket: 1. When generating a `Rep`/`Rep1` instance [http://git.haskell.org/ghc.git/blob/eb6b7094c80fda5cc7c1d1ed3386486996f24bff... here], do the appropriate type variable substitutions depending on the types the user provides. 2. Remove the broken instantiation check [http://git.haskell.org/ghc.git/blob/eb6b7094c80fda5cc7c1d1ed3386486996f24bff... here]. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11732#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler