🐛 fix(tsan): initialise libxml2 at load time via C constructor#34
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Add `XMLNode.lineNumber: Int?` backed by `xmlGetLineNo()` from libxml2. Returns the 1-based source line number recorded during parsing, or `nil` when unavailable (programmatically created nodes or libxml2 returns 0). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Under ThreadSanitizer, TSan's pthread interceptors interfere with libxml2's internal pthread_once guard inside xmlInitParser(), leaving the encoding-handler table NULL when xmlGetCharEncodingHandler is called from a concurrent thread — causing a SEGV in the warm-up that was meant to prevent that very crash. Add an __attribute__((constructor)) in SwiftXMLCoderCShim.c that runs xmlInitParser() and the UTF-8 handler warm-up at library-load time, in a single-threaded context, before TSan instruments any pthread primitives. This guarantees libxml2's global tables are fully populated before any thread is created. LibXML2.initializeOnce now only calls xmlInitParser() as a no-op safeguard for static-linking configurations that do not run constructors. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
__attribute__((constructor))inSwiftXMLCoderCShim.cthat callsxmlInitParser()and pre-warms the UTF-8 encoding handler at library-load time, in a single-threaded contextswiftxmlcoder_warm_encoding_handlercall fromLibXML2.initializeOnce(now handled by the constructor)test_encodeDecode_concurrent_roundTripreported on PR ⬆️ chore: bump actions/github-script from 7 to 8 #31Root cause
Under TSan, its pthread interceptors interfere with libxml2's internal
pthread_onceguard insidexmlInitParser(). This leaves the encoding-handler table NULL whenxmlGetCharEncodingHandleris subsequently called — causing a SEGV in the very warm-up that was meant to prevent that crash. Moving initialisation to a C constructor ensures it runs before TSan instruments any pthread primitive.Test plan
Concurrency (TSan, ubuntu-22.04)) passes🤖 Generated with Claude Code