#15954: LiberalTypeSynonyms unsaturation check doesn't kick in -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler (Type | Version: 8.6.2 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts | Unknown/Multiple invalid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Sorry to be slow. 1. Yes, this is a good message 2. I'm not so bothered here. Is it really better to say `Illegal polymorphic type: PolyId`? It doesn't look polymorphic. (In (1) would you have preferred `Illegal polymorphic type A`? That doesn't look polymorphic either. Also if we had {{{ type A = (forall a. a->a) -> Int foo :: F A foo = ... }}} we couldn't possibly report in terms of `A`. It's easy to see why it happens: we've moved synonym expansion first! 3. `tc149`. Yes I agree, it should have `Language LiberalTypeSynonyms` at the top. I think the test predates the flag. This change fixes an outright bug; and I think the regression is arguably and improvement. So let's do it! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15954#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler