[GHC] #10873: Bad error message for incorrect pattern synonym signature

[GHC]

#10873: Bad error message for incorrect pattern synonym signature
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        Reporter:  mpickering        |                Owner:  rdragon
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  7.10.2
  checker)                           |             Keywords:
      Resolution:                    |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1866
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"116528c8429257a0ae855251fd266547bb23d01d/ghc" 116528c/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="116528c8429257a0ae855251fd266547bb23d01d"
 Improve pattern synonym error messages (add `PatSynOrigin`)

 Adds a new data constructor `PatSynOrigin Bool Name` to the `CtOrigin`
 data type. This allows for better error messages when the origin of a
 wanted constraint is a pattern synonym declaration.

 Fixes T10873.

 Reviewers: mpickering, simonpj, austin, thomie, bgamari

 Reviewed By: simonpj, thomie, bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1866

 GHC Trac Issues: #10873
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10873#comment:10>
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