Make Reference concurrency safe - #880
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@swift-ci Please test Linux platform |
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The
Referencetype in theRegexBuildermodule uses an unprotectedstatic var counter: Intas a source of unique IDs, which can fail due to a race when used in concurrent contexts. This switches to using a newAtomicCountertype, which uses an (~internal) standard library entry point for loading/incrementing an atomic integer.Note that this only shows up as a bug when the race leads to multiple references inside a single builder
Regexwith identical IDs, which is considerably more rare than the race itself, so the last test inReferenceConcurrencyTests.swiftonly fails occasionally when run against the existing version.rdar://180971141