[GHC] #12087: Inconsistency in GADTs?

[GHC]

#12087: Inconsistency in GADTs?
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  task              |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  GADTs
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11540            |  Differential Rev(s):  Phab:D3851
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"039fa1b994a8b0d6be25eb1bc711904db9661db2/ghc"
 039fa1b9/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="039fa1b994a8b0d6be25eb1bc711904db9661db2"
 Suggest how to fix illegally nested foralls in GADT constructor type
 signatures

 Summary:
 Although the code from #12087 isn't accepted by GHC, we can at least
 do a better job of letting users know what the problem is, and how to fix
 it.

 Test Plan: make test TEST=T12087

 Reviewers: goldfire, austin, bgamari

 Reviewed By: goldfire

 Subscribers: rwbarton, thomie

 GHC Trac Issues: #12087

 Differential Revision: https://phabricator.haskell.org/D3851
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12087#comment:10>
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