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Assertion failure in serialization when building swift-syntax with swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm #84140

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#84215
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Assertion failure in serialization when building swift-syntax with swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm#84140
#84215
Labels
bugA deviation from expected or documented behavior. Also: expected but undesirable behavior.crashBug: A crash, i.e., an abnormal termination of softwaretriage neededThis issue needs more specific labels
@kkebo

Description

@kkebo
kkebo
opened on Sep 6, 2025

Description

If I try to build swift-syntax with the latest Swift Wasm SDK (swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm), the compiler crashes every time. Other repositories don’t face such a problem.

Reproduction

$ git clone https://github.com/swiftlang/swift-syntax
...
$ cd swift-syntax
$ swiftly install --use -y main-snapshot-2025-09-04
...
$ swiftly list
Installed release toolchains
----------------------------
...

Installed snapshot toolchains
-----------------------------
main-snapshot-2025-09-04 (in use)
$ swift sdk install https://download.swift.org/development/wasm-sdk/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle.tar.gz --checksum 4b2e574579826af744fe1330fcd54e762fa406b71f0032959b4f7508265a9c03
...
$ swift sdk list
swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm
swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm-embedded
$ swift build --swift-sdk swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm
Building for debugging...
error: emit-module command failed due to signal 6 (use -v to see invocation)
Assertion failed: (llvm::isUInt<Width>(data) && "data value does not fit in the given bit width"), function assertValid, file BitcodeConvenience.h, line 94.
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.      Program arguments: /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend -frontend -emit-module -experimental-skip-non-inlinable-function-bodies-without-types /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/CompilerPluginMessageHandler.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/Diagnostics.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/CodingUtilities.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSON.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSONDecoding.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSONEncoding.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/LRUCache.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/Macros.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMacroExpansionContext.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMessageCompatibility.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMessages.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/StandardIOMessageConnection.swift -target wasm32-unknown-wasip1 -disable-objc-interop -sdk /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/WASI.sdk -I /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules -color-diagnostics -Xcc -fcolor-diagnostics -enable-testing -g -debug-info-format=dwarf -dwarf-version=4 -module-cache-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/ModuleCache -swift-version 6 -Onone -D SWIFT_PACKAGE -D DEBUG -D SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE -empty-abi-descriptor -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/plugins/testing -resource-dir /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/swift.z/usr/bin/swift-frontend+0x105a539f4)
 #1 0x0000000107f5a120 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a52120)
 #2 0x0000000107f5c03c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a5403c)
 #3 0x0000000197dc4704 (/usr/lib/system/libsystem_platform.dylib+0x1804d4704)
 #4 0x0000000197dba848 (/usr/lib/system/libsystem_pthread.dylib+0x1804ca848)
 #5 0x0000000197cc0808 (/usr/lib/system/libsystem_c.dylib+0x1803d0808)
 #6 0x0000000197cbfa3c (/usr/lib/system/libsystem_c.dylib+0x1803cfa3c)
 #7 0x0000000107f95abc (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a8dabc)
 #8 0x0000000102fd4b18 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100accb18)
 #9 0x0000000102fc70f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abf0f4)
#10 0x0000000102fbb194 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab3194)
#11 0x0000000102fbaed0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab2ed0)
#12 0x0000000102fbcbe8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4be8)
#13 0x0000000102fbca48 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4a48)
#14 0x0000000102fbe6b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab66b0)
#15 0x0000000102fc5358 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abd358)
#16 0x0000000102a43690 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10053b690)
#17 0x000000010256708c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10005f08c)
#18 0x0000000102a433e0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10053b3e0)
#19 0x00000001027cc638 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c4638)
#20 0x0000000103eb3ab0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1019abab0)
#21 0x00000001027cc5b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c45b0)
#22 0x00000001030e3c28 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100bdbc28)
#23 0x00000001035e8c34 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1010e0c34)
#24 0x00000001034cf6d8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc76d8)
#25 0x00000001034d206c (/Users/kebo/Library/Developer/Toolchahctoolchain/usr/lib/swift_static -use-static-resource-dir -enable-anonymous-context-mangled-names -file-compilation-dir /Users/kebo/swift-syntax -Xcc -fmodule-map-file=/Users/kebo/swift-syntax/Sources/_SwiftSyntaxCShims/include/module.modulemap -Xcc -I -Xcc /Users/kebo/swift-syntax/Sources/_SwiftSyntaxCShims/include -Xcc --sysroot -Xcc /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/WASI.sdk -Xcc -g -no-auto-bridging-header-chaining -module-name SwiftCompilerPluginMessageHandling -package-name swift_syntax -in-process-plugin-server-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/libSwiftInProcPluginServer.dylib -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/local/lib/swift/host/plugins -emit-module-doc-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftdoc -emit-module-source-info-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftsourceinfo -emit-objc-header-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/include/SwiftCompilerPluginMessageHandlinens/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fca06c)
#26 0x00000001034cc348 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc4348)
#27 0x00000001034cc2c8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc42c8)
#28 0x00000001034f3450 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100feb450)
#29 0x00000001034d3d44 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fcbd44)
#30 0x00000001034cc540 (/Users/kebo/Library/Developer/Toolchains/-Swift.h -serialize-diagnostics-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/SwiftCompilerPluginMessageHandling.emit-module.dia -emit-dependencies-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/SwiftCompilerPluginMessageHandling.emit-module.d -parse-as-library -o /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftmodule
1.      Apple Swift version 6.2-dev (LLVM d04575f608ab42f, Swift cbcef93a5469a1a)
2.      Compiling with the current language version
3.      While evaluating request ExecuteSILPipelineRequest(Run pipelines { Non-Diagnostic Mandatory Optimizations, Serialization } on SIL for SwiftCompilerPluginMessageHandling)
4.      While running pass #2155 SILModuleTransform "SerializeSILPass".
5.      While serializing 'wasmPump()' (at /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/CompilerPluginMessageHandler.swift:287:1)
 #0 0x0000000107f5b9f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a539f4)
 #1 0x0000000107f5a120 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a52120)
 #2 0x0000000107f5c03c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a5403c)
 #3 0x0000000197dc4704 (/usr/lib/system/libsystem_platform.dylib+0x1804d4704)
 #4 0x0000000197dba848 (/usr/lib/system/libsystem_pthread.dylib+0x1804ca848)
 #5 0x0000000197cc0808 (/usr/lib/system/libsystem_c.dylib+0x1803d0808)
 #6 0x0000000197cbfa3c (/usr/lib/system/libsystem_c.dylib+0x1803cfa3c)
 #7 0x0000000107f95abc (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a8dabc)
 #8 0x0000000102fd4b18 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100accb18)
 #9 0x0000000102fc70f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abf0f4)
#10 0x0000000102fbb194 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab3194)
#11 0x0000000102fbaed0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab2ed0)
#12 0x0000000102fbcbe8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4be8)
#13 0x0000000102fbca48 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4a48)
#14 0x0000000102fbe6b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab66b0)
#15 0x0000000102fc5358 (/Users/kebo/Library/Developer/Toswift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc4540)
#31 0x00000001034d5574 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fcd574)
#32 0x0000000102a10744 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100508744)
#33 0x00000001027c6588 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002be588)
#34 0x00000001027c6100 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002be100)
#35 0x00000001027d5e4c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002cde4c)
#36 0x00000001027c9a94 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c1a94)
#37 0x00000001027c71d0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002bf1d0)
#38 0x0000000102540510 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100038510)
#39 0x00000001979fd924
[345/366] Emitting module SwiftSyntaxMacrosTestSupport

Stack dump

Assertion failed: (llvm::isUInt<Width>(data) && "data value does not fit in the given bit width"), function assertValid, file BitcodeConvenience.h, line 94.
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.      Program arguments: /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend -frontend -emit-module -experimental-skip-non-inlinable-function-bodies-without-types /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/CompilerPluginMessageHandler.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/Diagnostics.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/CodingUtilities.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSON.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSONDecoding.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/JSON/JSONEncoding.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/LRUCache.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/Macros.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMacroExpansionContext.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMessageCompatibility.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/PluginMessages.swift /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/StandardIOMessageConnection.swift -target wasm32-unknown-wasip1 -disable-objc-interop -sdk /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/WASI.sdk -I /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules -color-diagnostics -Xcc -fcolor-diagnostics -enable-testing -g -debug-info-format=dwarf -dwarf-version=4 -module-cache-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/ModuleCache -swift-version 6 -Onone -D SWIFT_PACKAGE -D DEBUG -D SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE -empty-abi-descriptor -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/plugins/testing -resource-dir /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/swift.z/usr/bin/swift-frontend+0x105a539f4)
 #1 0x0000000107f5a120 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a52120)
 #2 0x0000000107f5c03c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a5403c)
 #3 0x0000000197dc4704 (/usr/lib/system/libsystem_platform.dylib+0x1804d4704)
 #4 0x0000000197dba848 (/usr/lib/system/libsystem_pthread.dylib+0x1804ca848)
 #5 0x0000000197cc0808 (/usr/lib/system/libsystem_c.dylib+0x1803d0808)
 #6 0x0000000197cbfa3c (/usr/lib/system/libsystem_c.dylib+0x1803cfa3c)
 #7 0x0000000107f95abc (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a8dabc)
 #8 0x0000000102fd4b18 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100accb18)
 #9 0x0000000102fc70f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abf0f4)
#10 0x0000000102fbb194 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab3194)
#11 0x0000000102fbaed0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab2ed0)
#12 0x0000000102fbcbe8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4be8)
#13 0x0000000102fbca48 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4a48)
#14 0x0000000102fbe6b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab66b0)
#15 0x0000000102fc5358 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abd358)
#16 0x0000000102a43690 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10053b690)
#17 0x000000010256708c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10005f08c)
#18 0x0000000102a433e0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x10053b3e0)
#19 0x00000001027cc638 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c4638)
#20 0x0000000103eb3ab0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1019abab0)
#21 0x00000001027cc5b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c45b0)
#22 0x00000001030e3c28 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100bdbc28)
#23 0x00000001035e8c34 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1010e0c34)
#24 0x00000001034cf6d8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc76d8)
#25 0x00000001034d206c (/Users/kebo/Library/Developer/Toolchahctoolchain/usr/lib/swift_static -use-static-resource-dir -enable-anonymous-context-mangled-names -file-compilation-dir /Users/kebo/swift-syntax -Xcc -fmodule-map-file=/Users/kebo/swift-syntax/Sources/_SwiftSyntaxCShims/include/module.modulemap -Xcc -I -Xcc /Users/kebo/swift-syntax/Sources/_SwiftSyntaxCShims/include -Xcc --sysroot -Xcc /Users/kebo/Library/org.swift.swiftpm/swift-sdks/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm.artifactbundle/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a_wasm/wasm32-unknown-wasip1/WASI.sdk -Xcc -g -no-auto-bridging-header-chaining -module-name SwiftCompilerPluginMessageHandling -package-name swift_syntax -in-process-plugin-server-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/libSwiftInProcPluginServer.dylib -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/local/lib/swift/host/plugins -emit-module-doc-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftdoc -emit-module-source-info-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftsourceinfo -emit-objc-header-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/include/SwiftCompilerPluginMessageHandlinens/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fca06c)
#26 0x00000001034cc348 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc4348)
#27 0x00000001034cc2c8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc42c8)
#28 0x00000001034f3450 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100feb450)
#29 0x00000001034d3d44 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fcbd44)
#30 0x00000001034cc540 (/Users/kebo/Library/Developer/Toolchains/-Swift.h -serialize-diagnostics-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/SwiftCompilerPluginMessageHandling.emit-module.dia -emit-dependencies-path /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/SwiftCompilerPluginMessageHandling.build/SwiftCompilerPluginMessageHandling.emit-module.d -parse-as-library -o /Users/kebo/swift-syntax/.build/wasm32-unknown-wasip1/debug/Modules/SwiftCompilerPluginMessageHandling.swiftmodule
1.      Apple Swift version 6.2-dev (LLVM d04575f608ab42f, Swift cbcef93a5469a1a)
2.      Compiling with the current language version
3.      While evaluating request ExecuteSILPipelineRequest(Run pipelines { Non-Diagnostic Mandatory Optimizations, Serialization } on SIL for SwiftCompilerPluginMessageHandling)
4.      While running pass #2155 SILModuleTransform "SerializeSILPass".
5.      While serializing 'wasmPump()' (at /Users/kebo/swift-syntax/Sources/SwiftCompilerPluginMessageHandling/CompilerPluginMessageHandler.swift:287:1)
 #0 0x0000000107f5b9f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a539f4)
 #1 0x0000000107f5a120 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a52120)
 #2 0x0000000107f5c03c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a5403c)
 #3 0x0000000197dc4704 (/usr/lib/system/libsystem_platform.dylib+0x1804d4704)
 #4 0x0000000197dba848 (/usr/lib/system/libsystem_pthread.dylib+0x1804ca848)
 #5 0x0000000197cc0808 (/usr/lib/system/libsystem_c.dylib+0x1803d0808)
 #6 0x0000000197cbfa3c (/usr/lib/system/libsystem_c.dylib+0x1803cfa3c)
 #7 0x0000000107f95abc (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x105a8dabc)
 #8 0x0000000102fd4b18 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100accb18)
 #9 0x0000000102fc70f4 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100abf0f4)
#10 0x0000000102fbb194 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab3194)
#11 0x0000000102fbaed0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab2ed0)
#12 0x0000000102fbcbe8 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4be8)
#13 0x0000000102fbca48 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab4a48)
#14 0x0000000102fbe6b0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100ab66b0)
#15 0x0000000102fc5358 (/Users/kebo/Library/Developer/Toswift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fc4540)
#31 0x00000001034d5574 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100fcd574)
#32 0x0000000102a10744 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100508744)
#33 0x00000001027c6588 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002be588)
#34 0x00000001027c6100 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002be100)
#35 0x00000001027d5e4c (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002cde4c)
#36 0x00000001027c9a94 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002c1a94)
#37 0x00000001027c71d0 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x1002bf1d0)
#38 0x0000000102540510 (/Users/kebo/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a.xctoolchain/usr/bin/swift-frontend+0x100038510)
#39 0x00000001979fd924

Expected behavior

It won't crash.

Environment

$ swiftc --version
Apple Swift version 6.2-dev (LLVM d04575f608ab42f, Swift cbcef93a5469a1a)
Target: arm64-apple-macosx26.0
Build config: +assertions

Additional information

Logs: https://github.com/kkebo/swift-syntax/actions/runs/17513797710/job/49748786341

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    bugA deviation from expected or documented behavior. Also: expected but undesirable behavior.crashBug: A crash, i.e., an abnormal termination of softwaretriage neededThis issue needs more specific labels

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