#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: 9123, 14883 Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Ah, my apologies. I interpreted that list of bullet points as three separate criteria under which `deriving` would fail, not as a list of three conditions which must simultaneously hold. In that case, I feel much better about this idea (if this really is the only way forward). I've always thought that derived instance methods should use `InstanceSigs`, and this gives us a good excuse to do so. (And I think certain folks, possibly from Iceland, will find that more aesthetically pleasing to look at in `-ddump-deriv` output.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15290#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler