[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:"13e40f998e15a626a4212bde0987ddbc98b3f56f/ghc"
 13e40f99/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="13e40f998e15a626a4212bde0987ddbc98b3f56f"
 Kill varEnvElts in tcPragExpr

 I had to refactor some things to take VarSet instead of [Var],
 but I think it's more precise this way.

 Test Plan: ./validate

 Reviewers: simonmar, simonpj, austin, bgamari, goldfire

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2227

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:174>
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