1. 19 Oct, 2017 1 commit
    • Ryan Scott's avatar
      Error when deriving instances in hs-boot files · 101a8c77
      Ryan Scott authored
      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
      101a8c77