#15318: Core Lint error involving newtype family instances with wrappers -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.4.3 checker) | Resolution: | Keywords: TypeFamilies Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4902 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott <ryan.gl.scott@…>): In [changeset:"927518668111584a06f12bd9eb1b0910a38acf4f/ghc" 9275186/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="927518668111584a06f12bd9eb1b0910a38acf4f" Fix newtype instance GADTs Summary: This was taken from Richard's branch, which in turn was submitted to Phab by Matthew, which in turn was commandeered by Ryan. This fixes an issue with newtype instances in which too many coercions were being applied in the worker. This fixes the issue by removing the data family instance axiom from the worker and moving to the wrapper. Moreover, we now require all newtype instances to have wrappers, for symmetry with data instances. Reviewers: goldfire, bgamari, simonpj, mpickering Reviewed By: mpickering Subscribers: simonpj, rwbarton, thomie, carter GHC Trac Issues: #15318 Differential Revision: https://phabricator.haskell.org/D4902 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15318#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler