Re: [GHC] #16391: "Quantified type's kind mentions quantified type variable" error with fancy-kinded GADT

#16391: "Quantified type's kind mentions quantified type variable" error with fancy-kinded GADT -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.10.1 Component: Compiler (Type | Version: 8.6.3 checker) | Resolution: fixed | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | dependent/should_compile/T16391a, | dependent/should_fail/T16391b Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | https://gitlab.haskell.org/ghc/ghc/merge_requests/503 -------------------------------------+------------------------------------- Comment (by Marge Bot ): In [changeset:"068b7e983f4a0b35f453aa5e609998efd0c3f334/ghc" 068b7e98/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="068b7e983f4a0b35f453aa5e609998efd0c3f334" Fix #16391 by using occCheckExpand in TcValidity The type-variables-escaping-their-scope-via-kinds check in `TcValidity` was failing to properly expand type synonyms, which led to #16391. This is easily fixed by using `occCheckExpand` before performing the validity check. Along the way, I refactored this check out into its own function, and sprinkled references to Notes to better explain all of the moving parts. Many thanks to @simonpj for the suggestions. Bumps the haddock submodule. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16391#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler