Reliable crash shortly after initialization on Windows

[z2oh]

I have stack traces this time!

The crash occurs on this line when trying to copy out a compiler flag from a deallocated buffer.

00 000000f1`762f9ac0 00007ffc`b0c2868d     vrfcore!VerifierStopMessageEx+0x81e
01 000000f1`762f9e20 00007ffc`a4717383     vrfcore!VfCoreRedirectedStopMessage+0x8d
02 000000f1`762f9eb0 00007ffc`c4e7636f     verifier!VerifierStopMessage+0xc3
03 000000f1`762f9f60 00007ffc`90f82853     ntdll!RtlApplicationVerifierStop+0xef
04 000000f1`762f9fd0 00007ffc`90f836a0     vfbasics!VerifierStopMessage+0x223
05 000000f1`762fa030 00007ffc`90f82bfa     vfbasics!AVrfpCheckFirstChanceException+0x148
06 000000f1`762fa0c0 00007ffc`c4e07a8a     vfbasics!AVrfpVectoredExceptionHandler+0x1a
07 000000f1`762fa110 00007ffc`c4dae242     ntdll!RtlpCallVectoredHandlers+0x112
08 000000f1`762fa1b0 00007ffc`c4e3340e     ntdll!RtlDispatchException+0x62
09 000000f1`762fa400 00007ffc`497211a3     ntdll!KiUserExceptionDispatch+0x2e
0a 000000f1`762fab38 00007ffb`bd224268     VCRUNTIME140!memcpy+0xe3 [D:\a\_work\1\s\src\vctools\crt\vcruntime\src\string\amd64\memcpy.asm @ 191] 
0b (Inline Function) --------`--------     sourcekitdInProc!std::_Char_traits<char,int>::copy+0x5 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xstring @ 64] 
0c 000000f1`762fab40 00007ffb`c04b364b     sourcekitdInProc!std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Construct<1,char const *>+0x48 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xstring @ 2663] 
0d (Inline Function) --------`--------     sourcekitdInProc!std::basic_string<char,std::char_traits<char>,std::allocator<char> >::{ctor}+0x1f [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xstring @ 2905] 
0e (Inline Function) --------`--------     sourcekitdInProc!std::_Default_allocator_traits<std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::construct+0x1f [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xmemory @ 723] 
0f (Inline Function) --------`--------     sourcekitdInProc!std::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::_Emplace_back_with_unused_capacity+0x1f [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\vector @ 798] 
10 000000f1`762fab70 00007ffb`c04d6529     sourcekitdInProc!std::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::_Emplace_one_at_back<llvm::StringRef &>+0x3b [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\vector @ 780] 
11 (Inline Function) --------`--------     sourcekitdInProc!std::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::emplace_back+0xd [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\vector @ 862] 
12 000000f1`762fabb0 00007ffb`c04e663d     sourcekitdInProc!swift::importer::addCommonInvocationArguments+0x869 [C:\a\swift-build\swift-build\SourceCache\swift\lib\ClangImporter\ClangImporter.cpp @ 842] 
13 000000f1`762fadb0 00007ffb`c04e5a5a     sourcekitdInProc!swift::ClangImporter::getClangDriverArguments+0xad [C:\a\swift-build\swift-build\SourceCache\swift\lib\ClangImporter\ClangImporter.cpp @ 1074] 
14 000000f1`762fae70 00007ffb`c04da8f9     sourcekitdInProc!swift::ClangImporter::getClangCC1Arguments+0x31a [C:\a\swift-build\swift-build\SourceCache\swift\lib\ClangImporter\ClangImporter.cpp @ 1130] 
15 000000f1`762fb120 00007ffb`bf10d1df     sourcekitdInProc!swift::ClangImporter::create+0x6c9 [C:\a\swift-build\swift-build\SourceCache\swift\lib\ClangImporter\ClangImporter.cpp @ 1267] 
16 000000f1`762fb9b0 00007ffb`bf10c846     sourcekitdInProc!swift::CompilerInstance::setUpModuleLoaders+0x4bf [C:\a\swift-build\swift-build\SourceCache\swift\lib\Frontend\Frontend.cpp @ 772] 
17 000000f1`762fd890 00007ffb`bf10e6df     sourcekitdInProc!swift::CompilerInstance::setUpASTContextIfNeeded+0x1f6 [C:\a\swift-build\swift-build\SourceCache\swift\lib\Frontend\Frontend.cpp @ 329] 
18 000000f1`762fd8f0 00007ffb`bcfe0e2a     sourcekitdInProc!swift::CompilerInstance::setup+0x35f [C:\a\swift-build\swift-build\SourceCache\swift\lib\Frontend\Frontend.cpp @ 532] 
19 (Inline Function) --------`--------     sourcekitdInProc!`anonymous namespace'::ASTBuildOperation::buildASTUnit+0x805 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 1102] 
1a (Inline Function) --------`--------     sourcekitdInProc!`anonymous namespace'::ASTBuildOperation::schedule::<lambda_6>::operator()+0x94e [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 1208] 
1b 000000f1`762fd990 00007ffb`bcf8f51e     sourcekitdInProc!SourceKit::WorkQueue::DispatchData::callAndDelete<`lambda at C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp:1180:7'>+0x97a [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\include\SourceKit\Support\Concurrency.h @ 214] 
1c 000000f1`762ffd00 00007ffb`bcf8f54e     sourcekitdInProc!executeBlock+0xe [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\Support\Concurrency-libdispatch.cpp @ 103] 
1d (Inline Function) --------`--------     sourcekitdInProc!llvm::thread::GenericThreadProxy<std::tuple<void (*)(void *),void *> >::<lambda_1>::operator()+0x6 [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 43] 
1e (Inline Function) --------`--------     sourcekitdInProc!std::invoke+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\type_traits @ 1741] 
1f (Inline Function) --------`--------     sourcekitdInProc!std::_Apply_impl+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\tuple @ 1077] 
20 (Inline Function) --------`--------     sourcekitdInProc!std::apply+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\tuple @ 1088] 
21 (Inline Function) --------`--------     sourcekitdInProc!llvm::thread::GenericThreadProxy+0x6 [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 41] 
22 000000f1`762ffd30 00007ffc`c2739363     sourcekitdInProc!llvm::thread::ThreadProxy<std::tuple<void (*)(void *),void *> >+0xe [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 65] 
23 000000f1`762ffd60 00007ffc`90f9786e     ucrtbase!thread_start<unsigned int (__cdecl*)(void *),1>+0x93
24 000000f1`762ffd90 00007ffc`c41b257d     vfbasics!AVrfpStandardThreadFunction+0x4e
25 000000f1`762ffdd0 00007ffc`c4deaa58     KERNEL32!BaseThreadInitThunk+0x1d
26 000000f1`762ffe00 00000000`00000000     ntdll!RtlUserThreadStart+0x28

The string ref into the argument list is captured here, but the compiler invocation object is decallocated with extant references stored in the ASTContext.

Here's a trace of the reference being captured:

00 000000f1`769f67a0 00007ffb`bf0feb3f     sourcekitdInProc!ParseSearchPathArgs+0x11df [C:\a\swift-build\swift-build\SourceCache\swift\lib\Frontend\CompilerInvocation.cpp @ 1970] 
01 000000f1`769f6c10 00007ffb`bef424fe     sourcekitdInProc!swift::CompilerInvocation::parseArgs+0x4bf [C:\a\swift-build\swift-build\SourceCache\swift\lib\Frontend\CompilerInvocation.cpp @ 3341] 
02 (Inline Function) --------`--------     sourcekitdInProc!swift::ide::initCompilerInvocation::__l2::<lambda_1>::operator()+0x7a [C:\a\swift-build\swift-build\SourceCache\swift\lib\IDETool\CompilerInvocation.cpp @ 185] 
03 000000f1`769f6e80 00007ffb`bfd3b615     sourcekitdInProc!llvm::function_ref<bool __cdecl(llvm::ArrayRef<char const *>)>::callback_fn<`swift::ide::initCompilerInvocation'::`2'::<lambda_1> >+0x7e [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\ADT\STLFunctionalExtras.h @ 47] 
04 (Inline Function) --------`--------     sourcekitdInProc!llvm::function_ref<bool __cdecl(llvm::ArrayRef<char const *>)>::operator()+0x1f [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\ADT\STLFunctionalExtras.h @ 68] 
05 000000f1`769f6ef0 00007ffb`bef43d1c     sourcekitdInProc!swift::driver::getSingleFrontendInvocationFromDriverArguments+0x7c5 [C:\a\swift-build\swift-build\SourceCache\swift\lib\Driver\FrontendUtil.cpp @ 144] 
06 000000f1`769f7260 00007ffb`bcfcac62     sourcekitdInProc!swift::ide::initCompilerInvocation+0x2cc [C:\a\swift-build\swift-build\SourceCache\swift\lib\IDETool\CompilerInvocation.cpp @ 192] 
07 (Inline Function) --------`--------     sourcekitdInProc!SourceKit::SwiftASTManager::initCompilerInvocation+0x9c [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 698] 
08 000000f1`769f76b0 00007ffb`bcfeefb4     sourcekitdInProc!SourceKit::SwiftASTManager::getTypecheckInvocation+0x392 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 754] 
09 000000f1`769ff430 00007ffb`bcf84bb7     sourcekitdInProc!SourceKit::SwiftLangSupport::getDiagnostics+0x104 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftSourceDocInfo.cpp @ 2241] 
0a (Inline Function) --------`--------     sourcekitdInProc!handleRequestDiagnostics::<lambda_26>::operator()+0x2dd [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 1893] 
0b (Inline Function) --------`--------     sourcekitdInProc!std::invoke+0x2dd [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\type_traits @ 1731] 
0c 000000f1`769ff5f0 00007ffb`bcf78fc7     sourcekitdInProc!std::_Func_impl_no_alloc<`lambda at C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp:1882:35',void>::_Do_call+0x2f7 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\functional @ 808] 
0d (Inline Function) --------`--------     sourcekitdInProc!std::_Func_class<void>::operator()+0xf [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\functional @ 854] 
0e (Inline Function) --------`--------     sourcekitdInProc!handleSemanticRequest::<lambda_33>::operator()+0xf [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 577] 
0f 000000f1`769ff840 00007ffb`bcf8f51e     sourcekitdInProc!SourceKit::WorkQueue::DispatchData::callAndDelete<`lambda at C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp:577:22'>+0x17 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\include\SourceKit\Support\Concurrency.h @ 215] 
10 000000f1`769ff870 00007ffb`bcf8f54e     sourcekitdInProc!executeBlock+0xe [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\Support\Concurrency-libdispatch.cpp @ 103] 
11 (Inline Function) --------`--------     sourcekitdInProc!llvm::thread::GenericThreadProxy<std::tuple<void (*)(void *),void *> >::<lambda_1>::operator()+0x6 [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 43] 
12 (Inline Function) --------`--------     sourcekitdInProc!std::invoke+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\type_traits @ 1741] 
13 (Inline Function) --------`--------     sourcekitdInProc!std::_Apply_impl+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\tuple @ 1077] 
14 (Inline Function) --------`--------     sourcekitdInProc!std::apply+0x6 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\tuple @ 1088] 
15 (Inline Function) --------`--------     sourcekitdInProc!llvm::thread::GenericThreadProxy+0x6 [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 41] 
16 000000f1`769ff8a0 00007ffc`c2739363     sourcekitdInProc!llvm::thread::ThreadProxy<std::tuple<void (*)(void *),void *> >+0xe [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Support\thread.h @ 65] 
17 000000f1`769ff8d0 00007ffc`90f9786e     ucrtbase!thread_start<unsigned int (__cdecl*)(void *),1>+0x93
18 000000f1`769ff900 00007ffc`c41b257d     vfbasics!AVrfpStandardThreadFunction+0x4e
19 000000f1`769ff940 00007ffc`c4deaa58     KERNEL32!BaseThreadInitThunk+0x1d
1a 000000f1`769ff970 00000000`00000000     ntdll!RtlUserThreadStart+0x28

and the backing argument list being subsequently deallocated:

00 (Inline Function) --------`--------     sourcekitdInProc!std::_Deallocate+0x18 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xmemory @ 264] 
01 (Inline Function) --------`--------     sourcekitdInProc!std::_Default_allocator_traits<std::allocator<std::_List_node<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,void *> > >::deallocate+0x18 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\xmemory @ 714] 
02 (Inline Function) --------`--------     sourcekitdInProc!std::_List_node<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,void *>::_Freenode0+0x18 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\list @ 312] 
03 (Inline Function) --------`--------     sourcekitdInProc!std::_List_node<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,void *>::_Freenode+0x52 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\list @ 318] 
04 000000f1`73ef6680 00007ffb`bfd3adcc     sourcekitdInProc!std::_List_node<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,void *>::_Free_non_head<std::allocator<std::_List_node<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,void *> > >+0x72 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\list @ 329] 
05 (Inline Function) --------`--------     sourcekitdInProc!std::list<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::_Tidy+0x13 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\list @ 1500] 
06 (Inline Function) --------`--------     sourcekitdInProc!std::list<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >::{dtor}+0x13 [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\list @ 1045] 
07 (Inline Function) --------`--------     sourcekitdInProc!llvm::opt::InputArgList::{dtor}+0x2a [C:\a\swift-build\swift-build\SourceCache\llvm-project\llvm\include\llvm\Option\ArgList.h @ 431] 
08 (Inline Function) --------`--------     sourcekitdInProc!std::default_delete<llvm::opt::InputArgList>::operator()+0x2a [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\memory @ 3170] 
09 000000f1`73ef66b0 00007ffb`bfd4f13b     sourcekitdInProc!std::unique_ptr<llvm::opt::InputArgList,std::default_delete<llvm::opt::InputArgList> >::~unique_ptr<llvm::opt::InputArgList,std::default_delete<llvm::opt::InputArgList> >+0x3c [C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.38.33130\include\memory @ 3280] 
0a 000000f1`73ef66e0 00007ffb`bfd3b66e     sourcekitdInProc!swift::driver::Compilation::~Compilation+0x6b [C:\a\swift-build\swift-build\SourceCache\swift\lib\Driver\Compilation.cpp @ 990] 
0b 000000f1`73ef6710 00007ffb`bef43d1c     sourcekitdInProc!swift::driver::getSingleFrontendInvocationFromDriverArguments+0x81e [C:\a\swift-build\swift-build\SourceCache\swift\lib\Driver\FrontendUtil.cpp @ 144] 
0c 000000f1`73ef6a80 00007ffb`bcfcac62     sourcekitdInProc!swift::ide::initCompilerInvocation+0x2cc [C:\a\swift-build\swift-build\SourceCache\swift\lib\IDETool\CompilerInvocation.cpp @ 192] 
0d (Inline Function) --------`--------     sourcekitdInProc!SourceKit::SwiftASTManager::initCompilerInvocation+0x9c [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 698] 
0e 000000f1`73ef6ed0 00007ffb`bcfca8bd     sourcekitdInProc!SourceKit::SwiftASTManager::getTypecheckInvocation+0x392 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 754] 
0f 000000f1`73efec50 00007ffb`bcfb44ed     sourcekitdInProc!SourceKit::SwiftASTManager::getTypecheckInvocation+0x5d [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftASTManager.cpp @ 739] 
10 (Inline Function) --------`--------     sourcekitdInProc!`anonymous namespace'::SwiftDocumentSemanticInfo::setCompilerArgs+0x96 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftEditor.cpp @ 685] 
11 000000f1`73efece0 00007ffb`bcfb8ee6     sourcekitdInProc!SourceKit::SwiftEditorDocument::initializeText+0x2ed [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftEditor.cpp @ 1990] 
12 000000f1`73efedf0 00007ffb`bcf6c038     sourcekitdInProc!SourceKit::SwiftLangSupport::editorOpen+0x316 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\lib\SwiftLang\SwiftEditor.cpp @ 2401] 
13 (Inline Function) --------`--------     sourcekitdInProc!editorOpen+0x18c [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 3581] 
14 (Inline Function) --------`--------     sourcekitdInProc!handleRequestEditorOpen+0x1050 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 821] 
15 (Inline Function) --------`--------     sourcekitdInProc!handleRequestImpl+0x2780 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 2088] 
16 000000f1`73efef80 00007ffb`bcf520d3     sourcekitdInProc!sourcekitd::handleRequest+0x28f8 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\lib\Service\Requests.cpp @ 400] 
17 (Inline Function) --------`--------     sourcekitdInProc!sourcekitd_send_request::<lambda_1>::operator()+0x2b [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\bin\InProc\sourcekitdInProc.cpp @ 170] 
18 000000f1`73eff620 00007ffc`83833b50     sourcekitdInProc!SourceKit::WorkQueue::DispatchData::callAndDelete<`lambda at C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\tools\sourcekitd\bin\InProc\sourcekitdInProc.cpp:169:18'>+0x33 [C:\a\swift-build\swift-build\SourceCache\swift\tools\SourceKit\include\SourceKit\Support\Concurrency.h @ 214] 
19 (Inline Function) --------`--------     dispatch!_dispatch_continuation_invoke_inline+0x8d [C:\a\swift-build\swift-build\SourceCache\swift-corelibs-libdispatch\src\inline_internal.h @ 2455] 
1a (Inline Function) --------`--------     dispatch!_dispatch_continuation_pop_inline+0xfb [C:\a\swift-build\swift-build\SourceCache\swift-corelibs-libdispatch\src\inline_internal.h @ 2498] 
1b (Inline Function) --------`--------     dispatch!_dispatch_root_queue_drain+0x1f0 [C:\a\swift-build\swift-build\SourceCache\swift-corelibs-libdispatch\src\queue.c @ 6114] 
1c (Inline Function) --------`--------     dispatch!_dispatch_worker_thread+0x2b3 [C:\a\swift-build\swift-build\SourceCache\swift-corelibs-libdispatch\src\queue.c @ 6249] 
1d 000000f1`73eff690 00007ffc`c2739363     dispatch!_dispatch_worker_thread_thunk+0x2e0 [C:\a\swift-build\swift-build\SourceCache\swift-corelibs-libdispatch\src\queue.c @ 6271] 
1e 000000f1`73eff750 00007ffc`90f9786e     ucrtbase!thread_start<unsigned int (__cdecl*)(void *),1>+0x93
1f 000000f1`73eff780 00007ffc`c41b257d     vfbasics!AVrfpStandardThreadFunction+0x4e
20 000000f1`73eff7c0 00007ffc`c4deaa58     KERNEL32!BaseThreadInitThunk+0x1d
21 000000f1`73eff7f0 00000000`00000000     ntdll!RtlUserThreadStart+0x28

I've been bisecting toolchain versions and it seems like this issue was introduced sometime around late February or early March (the toolchain we built on 2024/02/29 is good, but the one built on 2024/03/03 has this issue).

I'm continuing to investigate here, but wanted to flag early in case there's any insight or this has been reported elsewhere.

[ahoppen]

Thanks for investigating this @z2oh! I am not aware of any related issue.

[ahoppen]

Tracked in Apple’s issue tracker as rdar://125927586