Re: [GHC] #15787: GHC panic using kind application

#15787: GHC panic using kind application -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5275 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Richard Eisenberg ): In [changeset:"4427315a65b25db22e1754d41b43dd4b782b022f/ghc" 4427315/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4427315a65b25db22e1754d41b43dd4b782b022f" Fix #15787 by squashing a coercion hole. In type-incorrect code, we can sometimes let a coercion hole make it through the zonker. If this coercion hole then ends up in the environment (e.g., in the type of a data constructor), then it causes trouble later. This patch avoids trouble by substituting the coercion hole for its representative CoVar. Really, any coercion would do, but the CoVar was very handy. test case: polykinds/T15787 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15787#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler