[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:"586d55815401c54f4687d053fb033e53865e0bf1/ghc" 586d558/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="586d55815401c54f4687d053fb033e53865e0bf1"
 Use UniqFM for SigOf

 Summary:
 The Ord instance for ModuleName is currently implemented in
 terms of Uniques causing potential determinism problems.
 I plan to change it to use the actual FastStrings and in
 preparation for that I'm switching to UniqFM where it's
 possible (you need *one* Unique per key, and you can't get
 the keys back), so that the performance doesn't suffer.

 Test Plan: ./validate

 Reviewers: simonmar, austin, ezyang, bgamari

 Reviewed By: bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2320

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:208>
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