Re: [GHC] #14579: GeneralizedNewtypeDeriving produces ambiguously-kinded code

#14579: GeneralizedNewtypeDeriving produces ambiguously-kinded code -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.2 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4264 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott ): In [changeset:"649e777211fe08432900093002547d7358f92d82/ghc" 649e777/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="649e777211fe08432900093002547d7358f92d82" Make typeToLHsType produce kind signatures for tycon applications Summary: `GeneralizedNewtypeDeriving` generates calls to `coerce` which take visible type arguments. These types must be produced by way of `typeToLHsType`, which converts a `Type` to an `LHsType`. However, `typeToLHsType` was leaving off important kind information when a `Type` contained a poly-kinded tycon application, leading to incorrectly generated code in #14579. This fixes the issue by tweaking `typeToLHsType` to generate explicit kind signatures for tycon applications. This makes the generated code noisier, but at least the program from #14579 now works correctly. Test Plan: make test TEST=T14579 Reviewers: simonpj, bgamari Reviewed By: simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14579 Differential Revision: https://phabricator.haskell.org/D4264 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14579#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler