[GHC] #14135: PatternSynonyms regression in GHC HEAD (expectJust mkOneConFull)

[GHC]

#14135: PatternSynonyms regression in GHC HEAD (expectJust mkOneConFull)
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3981
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"16c7d9dc9ea7505256e0792c958cab8ae7c8a5c4/ghc"
 16c7d9dc/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="16c7d9dc9ea7505256e0792c958cab8ae7c8a5c4"
 Fix #14135 by validity checking matches

 We filter the complete patterns given in a COMPLETE set to only those that
 subsume the type we are matching. Otherwise we end up introducing an ill-
 typed
 equation into the overlap checking, provoking a crash. This was the cause
 of
 Trac #14135.

 Reviewers: austin, bgamari, mpickering, gkaracha, simonpj, RyanGlScott,
 carlostome

 Reviewed By: bgamari

 Subscribers: carter, dfeuer, RyanGlScott, goldfire, rwbarton, thomie

 GHC Trac Issues: #14135

 Differential Revision: https://phabricator.haskell.org/D3981
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14135#comment:21>
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