
#15052: DeriveAnyClass instances may skip TypeError constraints -------------------------------------+------------------------------------- Reporter: jcpetruzza | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.2 Resolution: | Keywords: | CustomTypeErrors 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 RyanGlScott): You've only presented me with the options that all three should be accepted, or all three should be rejected. I don't agree with either of those options. I think that, given the current established conventions for how `TypeError` works, the first option should be accepted, and the latter two options should be rejected. The first option is working in a fundamentally different way than the latter two, so it's foolhardy to try and equate them. I think there might be a different semantics for `TypeError` which would reject the first option. But I'd like to put an emphasis on "different". -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15052#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler