Re: [GHC] #14365: Panic with (bogus?) deriving in hs-boot: newTyConEtadArity

#14365: Panic with (bogus?) deriving in hs-boot: newTyConEtadArity -------------------------------------+------------------------------------- Reporter: happykitten | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4102 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott ): In [changeset:"101a8c770b9d3abd57ff289bffea3d838cf25c80/ghc" 101a8c7/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="101a8c770b9d3abd57ff289bffea3d838cf25c80" Error when deriving instances in hs-boot files Summary: According to the GHC users' guide, one cannot derive instances for data types in `.hs-boot` files. However, GHC was not enforcing this in practice, which led to #14365. Fix this by actually throwing an error if a derived instance is detected in an `.hs-boot` file (and recommend how to fix it in the error message.) Test Plan: make test TEST=T14365 Reviewers: ezyang, austin, bgamari, simonpj Reviewed By: simonpj Subscribers: simonpj, rwbarton, thomie GHC Trac Issues: #14365 Differential Revision: https://phabricator.haskell.org/D4102 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14365#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler