[GHC] #10831: Document conditions on deriving Functor

[GHC]

#10831: Document conditions on deriving Functor
-------------------------------------+-------------------------------------
        Reporter:  htebalaka         |                Owner:  RyanGlScott
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler (Type    |              Version:  7.10.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1293
-------------------------------------+-------------------------------------

Comment (by Austin Seipp <austin@…>):

 In [changeset:"e5bfd704a6391e74f3797d78d19c4e4877f512da/ghc" e5bfd70/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e5bfd704a6391e74f3797d78d19c4e4877f512da"
 docs: overhaul Derive{Functor,Foldable,Traversable} notes

 The previous users' guide documentation was too implementation-oriented.
 This
 attempts to make it more accessible to those who aren't familiar with how
 `-XDeriveFunctor` and friends work (and more importantly, what will not
 work
 when using them).

 Fixes #10831.

 Reviewed By: austin

 Differential Revision: https://phabricator.haskell.org/D1293

 GHC Trac Issues: #10831
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10831#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler