#15831: DerivingVia allows bogus implicit quantification in `via` type -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.6.1 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * milestone: => 8.8.1 Comment: I think I see what's going on here. The aforementioned validity check is currently implemented in the renamer (in [http://git.haskell.org/ghc.git/blob/331081b03f67c94b908136339aebf36d07d45c21... rnAndReportFloatingViaTvs]), but the renamer is completely oblivious to the existence of inferred kind variables (such as `k` in the original example). This leads me to believe that the renamer is the wrong place to put this check, and that it should really live in the typechecker, where we do know about the existence of `k`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15831#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler