#7451: Constraint and * should not be distinct in FC ---------------------------------+------------------------------------------ Reporter: simonpj | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.7 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ With GHC 7.7 this program {{{ class B a where b :: a
newtype Additive a = Additive a instance B a => B (Additive a) where b = Additive b }}} produces a Core Lint error: {{{ *** Core Lint errors : in result of Simplifier *** {-# LINE 8 "T6117.hs #-}: Warning: [RHS of T6117.$fBAdditive :: forall a_aeG. T6117.B a_aeG => T6117.B (T6117.Additive a_aeG)] Bad axiom application (check_ki2 Sym (T6117.NTCo:B (T6117.NTCo:Additive <a_XeN>)) Constraint a_aeF *) T6117.NTCo:B (Sym (T6117.NTCo:B (T6117.NTCo:Additive <a_XeN>))) }}} The reason is that while kinds `Constraint` and `*` should be distinct so far as the type inference engine is concerned, they should not be distinguished in Core, ie System FC. This ticket is culled from #6117, which was really about something else. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7451> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs