#13267: Constraint synonym instances -------------------------------------+------------------------------------- Reporter: ezyang | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.1 checker) | Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: GHC accepts | Test Case: invalid program | polykinds/T13267 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by niteria): I'd like to just note that https://github.com/niteria/dual- tree/blob/master/test/Test.hs now fails to build with: {{{ test/Test.hs:55:19: error: • Illegal instance for a type synonym A class instance must be for a class • In the stand-alone deriving instance for ‘Typeable1 Sum’ | 55 | deriving instance Typeable1 X.Sum | ^^^^^^^^^^^^^^^ test/Test.hs:56:19: error: • Illegal instance for a type synonym A class instance must be for a class • In the stand-alone deriving instance for ‘Typeable1 Product’ | 56 | deriving instance Typeable1 X.Product | ^^^^^^^^^^^^^^^^^^^ }}} I will attach a smaller example. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13267#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler