[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:  7.12.1
       Component:  Compiler          |                 Version:  6.12.2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Other             |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D1073
-------------------------------------+-------------------------------------

Comment (by Simon Marlow <marlowsd@…>):

 In [changeset:"3448f9827d2364b91bc60134aa38b74849b9d54e/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="3448f9827d2364b91bc60134aa38b74849b9d54e"
 Reduce non-determinism in ABI hashes with RULES and instance decls

 Summary:
 Before this change the `RULES` would be attached to one for the names from
 the module that appear on the left hand side. The choice depended on the
 `uniq` that was generated, which are known to be non-deterministic (a
 separate, bigger problem). Now we use `OccName`s which should be stable.

 Analogously for instance declarations, but they are attached to one of
 the types involved.

 Test Plan:
 contbuild
 it made `Data.Text.Internal.Fusion.Common` interface stable, previously
 stream fusion rule would be attached either to `streamList` or
 `unstreamList` depending on if the module was compiled after `cabal
 clean` or after `find | grep '\.o$' | xargs rm`.

 Reviewers: simonpj, austin, bgamari, simonmar

 Subscribers: puffnfresh, thomie

 Differential Revision: https://phabricator.haskell.org/D1073

 GHC Trac Issues: #4012
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:111>
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