[GHC] #4012: Compilation results are not deterministic

[GHC]

#4012: Compilation results are not deterministic
-------------------------------------+-------------------------------------
        Reporter:  kili              |                Owner:  niteria
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  6.12.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10424            |  Differential Rev(s):  Phab:D910,
                                     |  Phab:D1073, Phab:D1133, Phab:D1192,
                                     |  Phab:D1268, Phab:D1360, Phab:D1373,
                                     |  Phab:D1396, Phab:D1457, Phab:D1468,
       Wiki Page:                    |  Phab:D1487, Phab:D1504, Phab:D1508
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"6393dd8e437f68856b2e7889e576ed1bfb0a9678/ghc" 6393dd8/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="6393dd8e437f68856b2e7889e576ed1bfb0a9678"
 Make abstractVars deterministic in SetLevel

 This fixes a non-determinism bug where depending on the order
 of uniques allocated, the type variables would be in a different order
 when abstracted for the purpose of lifting out an expression.

 Test Plan:
 I've added a new testcase that reproduces the problem
 ./validate

 Reviewers: simonmar, austin, bgamari, simonpj

 Reviewed By: simonpj

 Subscribers: nomeata, thomie

 Differential Revision: https://phabricator.haskell.org/D1504

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:134>
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