Wasm CI (nightly-main) keeps failing

[kkebo]

The CI job "Pull request / Test / Swift SDK for Wasm Build (nightly-main - jammy) (pull_request)" keeps failing.

Error log: https://github.com/swiftlang/swift-syntax/actions/runs/27970621243/job/82775581996

According to my experiments, there are two main problems.

Main problems:

1. Error: Trap: out of bounds memory access
   • These errors are caused by swift-build and do not occur when using --build-system native.
2. ParserTests.testSelfParse is failing (No file descriptors available)

   Test Case 'ParserTests.testSelfParse' started at 1970-01-09 19:01:59.743
   Self-parse tests - processing 327 source files
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSelfParse : failed - Self-parse tests: file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSFilePath=/home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift, NSURL=file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift, NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available"}
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSelfParse : failed - Self-parse tests: file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/Utils.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSFilePath=/home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/Utils.swift, NSURL=file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/Utils.swift, NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available"}
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSelfParse : failed - Self-parse tests: file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/MissingNodesError.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSFilePath=/home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/MissingNodesError.swift, NSURL=file:///home/kebo/swift-syntax/Sources/SwiftParserDiagnostics/MissingNodesError.swift, NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available"}
   ...
   

   • I think the root cause might be WasmKit's file descriptor leak.
   • ✅ wasmtime run --dir / -W max-wasm-stack=16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest succeeds. (wasmtime 37.0.2)
   • ✅ ~/WasmKit/.build/release/wasmkit-cli run --dir .build --dir / --stack-size 16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest --filter SwiftParserTest.ParserTests/testSelfParse succeeds. (WasmKit main branch a0010b6eb445d87b26942466a574e1e8202e2cdb)
     • This may be released as WasmKit 0.3.0.
   • ❌ wasmkit run --dir .build --dir / --stack-size 16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest --filter SwiftParserTest.ParserTests/testSelfParse fails. (WasmKit 0.2.1 included in the Swift toolchain)

Minor problems:

1. ParserTests.testSwiftTestsuite is failing (No file descriptors available)

   Test Case 'ParserTests.testSwiftTestsuite' started at 2026-06-27 12:53:34.199
   Swift tests - processing 6920 source files
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSwiftTestsuite : failed - Swift tests: file:///home/kebo/swift/test/Sema/typo_correction_limit.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available", NSFilePath=/home/kebo/swift/test/Sema/typo_correction_limit.swift, NSURL=file:///home/kebo/swift/test/Sema/typo_correction_limit.swift}
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSwiftTestsuite : failed - Swift tests: file:///home/kebo/swift/test/Sema/immutability_overload_async.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSURL=file:///home/kebo/swift/test/Sema/immutability_overload_async.swift, NSFilePath=/home/kebo/swift/test/Sema/immutability_overload_async.swift, NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available"}
   /home/kebo/swift-syntax/Tests/SwiftParserTest/ParserTests.swift:79: error: ParserTests.testSwiftTestsuite : failed - Swift tests: file:///home/kebo/swift/test/Sema/clang_types_in_ast.swift failed due to Error Domain=NSCocoaErrorDomain Code=256 "(null)"UserInfo={NSURL=file:///home/kebo/swift/test/Sema/clang_types_in_ast.swift, NSFilePath=/home/kebo/swift/test/Sema/clang_types_in_ast.swift, NSUnderlyingError=Error Domain=NSPOSIXErrorDomain Code=33 "No file descriptors available"}
   ...
   

   • Since this test only runs when swiftlang/swift is checked out, it doesn't affect the CI.
   • ✅ wasmtime run --dir / -W max-wasm-stack=16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest succeeds. (wasmtime 37.0.2)
   • ❌ Even ~/WasmKit/.build/release/wasmkit-cli run --dir .build --dir / --stack-size 16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest --filter SwiftParserTest.ParserTests/testSwiftTestsuite fails. (WasmKit main branch a0010b6eb445d87b26942466a574e1e8202e2cdb)
     • -> ✅ It succeeds in WasmKit main branch (d7093272b9852999ff59fac9642962c84fc8d27a).
   • ❌ wasmkit run --dir .build --dir / --stack-size 16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest --filter SwiftParserTest.ParserTests/testSwiftTestsuite fails. (WasmKit 0.2.1 included in the Swift toolchain)

[kkebo]

ParserTests.testSwiftTestsuite is failing (No file descriptors available)

It has been fixed in PR swiftwasm/WasmKit#363. (Not yet released)

$ ~/WasmKit/.build/release/wasmkit-cli run --dir .build --dir / --stack-size 16777216 .build/wasm32-unknown-wasip1/release/swift-syntaxPackageTests.xctest --filter SwiftParserTest.ParserTests/testSwiftTestsuite
Test Suite 'Selected tests' started at 2026-06-28 07:12:20.659
Test Suite 'ParserTests' started at 2026-06-28 07:12:20.770
Test Case 'ParserTests.testSwiftTestsuite' started at 2026-06-28 07:12:20.771
Swift tests - processing 14149 source files
Test Case 'ParserTests.testSwiftTestsuite' passed (240.06 seconds)
Test Suite 'ParserTests' passed at 2026-06-28 07:16:20.833
         Executed 1 test, with 0 failures (0 unexpected) in 240.06 (240.06) seconds
Test Suite 'Selected tests' passed at 2026-06-28 07:16:20.834
         Executed 1 test, with 0 failures (0 unexpected) in 240.06 (240.06) seconds

And all the other tests passed successfully. 🎉

[kkebo]

Thank you, @MaxDesiatov. However, I wonder if the "out of bounds memory access" error is also resolved.

[MaxDesiatov]

Thank you, @MaxDesiatov. However, I wonder if the "out of bounds memory access" error is also resolved.

We did bump default stack size in the driver here not so long ago, hopefully that helps: swiftlang/swift-driver#2026

[kkebo]

I tested with Swift main-snapshot-2026-07-11 and WasmKit 0.3.1 on Linux aarch64 locally. It appears that swift-syntax's Wasm CI is not fixed yet if swift-build is used.

Commit: b8e7d60

--build-system native:

$ swift test -c release --explicit-target-dependency-import-check error --swift-sdk "$(swiftc -print-target-info | jq -r '.swiftCompilerTag')_wasm" --toolset Toolsets/wasi-test-toolset.json --build-system native
(All tests passed successfully)

--build-system swiftbuild (default):

$ swift test -c release --explicit-target-dependency-import-check error --swift-sdk "$(swiftc -print-target-info | jq -r '.swiftCompilerTag')_wasm" --toolset Toolsets/wasi-test-toolset.json
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftBasicFormat/SwiftBasicFormat.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftIfConfig/SwiftIfConfig.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftLexicalLookup/SwiftLexicalLookup.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftOperators/SwiftOperators.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftParser/SwiftParser.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftSyntax/Documentation.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftSyntaxBuilder/Documentation.docc
warning: 'swift-syntax': found 1 file(s) which are unhandled; explicitly declare them as resources or exclude from the target
    /home/kebo/swift-syntax/Sources/SwiftSyntaxMacros/SwiftSyntaxMacros.docc
Building for production...
/home/kebo/.local/share/swiftly/toolchains/main-snapshot-2026-07-11/usr/bin/llvm-ar: error: /home/kebo/swift-syntax/.build/out/Products/Release-webassembly-wasm32/libSwiftSyntax.a: 'SwiftSyntax.o': invalid data symbol offset: `$s11SwiftSyntax16AbsolutePositionVSQAAMc` (offset: 136 segment size: 55)
error: Libtool /home/kebo/swift-syntax/.build/out/Products/Release-webassembly-wasm32/libSwiftSyntax.a normal failed with a nonzero exit code. Command line:     cd /home/kebo/swift-syntax
    /home/kebo/.local/share/swiftly/toolchains/main-snapshot-2026-07-11/usr/bin/llvm-ar rcs /home/kebo/swift-syntax/.build/out/Products/Release-webassembly-wasm32/libSwiftSyntax.a @/home/kebo/swift-syntax/.build/out/Intermediates.noindex/swift-syntax.build/Release-webassembly-wasm32/SwiftSyntax-product-p.build/Objects-normal/wasm32/SwiftSyntax.LinkFileList

error: Build failed
error: fatalError

I couldn't check if the out of bounds memory access error still happens due to this llvm-ar error.

In any case, I'm reopening this issue.

[MaxDesiatov]

It appears that swift-syntax's Wasm CI is not fixed yet if swift-build is used.

@kkebo Would you mind filing a separate issue on the SwiftPM repository for this with the reproduction steps? Thank you!

[kkebo]

I see. I'll do it if that's more convenient.