#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 ): In [changeset:"0497ee504cc9ac5d6babee9b98bf779b3fc50b98/ghc" 0497ee5/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="0497ee504cc9ac5d6babee9b98bf779b3fc50b98" Make the Ord Module independent of Unique order The `Ord Module` instance currently uses `Unique`s for comparison. We don't want to use the `Unique` order because it can introduce nondeterminism. This switches `Ord ModuleName` and `Ord UnitId` to use lexicographic ordering making `Ord Module` deterministic transitively. I've run `nofib` and it doesn't make a measurable difference. See also Note [ModuleEnv determinism and performance]. Test Plan: ./validate run nofib: P112 Reviewers: simonpj, simonmar, austin, bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2030 GHC Trac Issues: #4012 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/4012#comment:209 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler