[GHC] #4012: Compilation results are not deterministic

[GHC]

#4012: Compilation results are not deterministic
-------------------------------------+-------------------------------------
        Reporter:  kili              |                Owner:  niteria
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  6.12.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:  11362             |             Blocking:
 Related Tickets:  #10424            |  Differential Rev(s):  Phab:D910,
                                     |  Phab:D1073, Phab:D1133, Phab:D1192,
                                     |  Phab:D1268, Phab:D1360, Phab:D1373,
       Wiki Page:                    |  Phab:D1396, Phab:D1457, Phab:D1468,
  DeterministicBuilds                |  Phab:D1487, Phab:D1504, Phab:D1508
-------------------------------------+-------------------------------------

Comment (by Bartosz Nitka <niteria@…>):

 In [changeset:"21fe4ffd049c8ab4b9ee36af3cf8f70b46d6beda/ghc" 21fe4ff/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="21fe4ffd049c8ab4b9ee36af3cf8f70b46d6beda"
 Kill varSetElems in tcInferPatSynDecl

 varSetElems introduces unnecessary non-determinism and while
 I didn't estabilish experimentally that this matters here
 I'm convinced that it will, because I expect pattern synonyms
 to end up in interface files.

 Test Plan: ./validate

 Reviewers: austin, simonmar, bgamari, mpickering, simonpj

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2206

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:169>
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