#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:"82538f65f48f370764691264c3c71b975fd43e16/ghc" 82538f65/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="82538f65f48f370764691264c3c71b975fd43e16" Kill varSetElems in injImproveEqns We want to remove varSetElems at the source level because it might be a source of nondeterminism. I don't think it introduces nondeterminism here, but it's easy to do the same thing deterministically for the same price. instFlexiTcS :: [TKVar] -> TcS (TCvSubst, [TcType]) instFlexiTcS currently gives the range of the produced substitution as the second element of the tuple, but it's not used anywhere right now. If it started to be used in the code I'm modifying it would cause nondeterminism problems. Test Plan: ./validate Reviewers: austin, goldfire, bgamari, simonmar, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2149 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:154> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler