error: clang frontend command failed due to signal (use -v to see invocation)

[debugzxcv]

clang++ -v -gcodeview -Xlinker "--pdb=" --static -Xclang -fasync-exceptions test.cc -o test.exe

Stack dump:
0.      Program arguments: G:/devenv/llvm-mingw-ucrt-x86_64/bin/clang-20.exe -cc1 -triple x86_64-w64-windows-gnu -emit-obj -dumpdir test.exe- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name test.cc -static-define -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -mms-bitfields -funwind-tables=2 -fno-sized-deallocation -fno-use-init-array -target-cpu x86-64 -tune-cpu generic -gno-column-info -gcodeview -debugger-tuning=gdb -fdebug-compilation-dir=G:/src/test -object-file-name=C:/Users/ADMINI~1/AppData/Local/Temp/test-befc2f.o -v -fcoverage-compilation-dir=G:/src/test -resource-dir G:/devenv/llvm-mingw-ucrt-x86_64/lib/clang/20 -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/x86_64-w64-mingw32/include/c++/v1 -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/include/c++/v1 -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/lib/clang/20/include -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/x86_64-w64-mingw32/include -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/x86_64-w64-mingw32/usr/include -internal-isystem G:/devenv/llvm-mingw-ucrt-x86_64/include -fdeprecated-macro -ferror-limit 19 -fmessage-length=120 -fno-use-cxa-atexit -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -exception-model=seh -fcolor-diagnostics -fasync-exceptions -faddrsig -o C:/Users/ADMINI~1/AppData/Local/Temp/test-befc2f.o -x c++ test.cc
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 'test.cc'.
4.      Running pass 'X86 DAG->DAG Instruction Selection' on function '@_ZN12SE_ExceptionD2Ev'
Exception Code: 0xC0000005
 #0 0x00007ffbabac2e63 llvm::FastISel::selectOperator(llvm::User const*, unsigned int) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x9d2e63)
 #1 0x00007ffbabac9725 llvm::FastISel::selectInstruction(llvm::Instruction const*) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x9d9725)
 #2 0x00007ffbabc8afb6 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0xb9afb6)
 #3 0x00007ffbabc8947c llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0xb9947c)
 #4 0x00007ffbada50c5d LLVMInitializeX86AsmPrinter (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x2960c5d)
 #5 0x00007ffbabc87b8d llvm::SelectionDAGISelLegacy::runOnMachineFunction(llvm::MachineFunction&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0xb97b8d)
 #6 0x00007ffbab6e22fb llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x5f22fb)
 #7 0x00007ffbab3d8cb6 llvm::FPPassManager::runOnFunction(llvm::Function&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x2e8cb6)
 #8 0x00007ffbab3e01a3 llvm::FPPassManager::runOnModule(llvm::Module&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x2f01a3)
 #9 0x00007ffbab3d9b19 llvm::legacy::PassManagerImpl::run(llvm::Module&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libLLVM-20.dll+0x2e9b19)
#10 0x00007ffbb7cc6bed clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::__1::unique_ptr<llvm::raw_pwrite_stream, std::__1::default_delete<llvm::raw_pwrite_stream>>, clang::BackendConsumer*) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x1366bed)
#11 0x00007ffbb80d183c clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x177183c)
#12 0x00007ffbb6b49f67 clang::ParseAST(clang::Sema&, bool, bool) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x1e9f67)
#13 0x00007ffbb8b65dcb clang::FrontendAction::Execute() (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x2205dcb)
#14 0x00007ffbb8ae3f04 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x2183f04)
#15 0x00007ffbb8be5ae2 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (G:\devenv\llvm-mingw-ucrt-x86_64\bin\libclang-cpp.dll+0x2285ae2)
#16 0x00007ff6a04568b5 (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x68b5)
#17 0x00007ff6a0453962 (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x3962)
#18 0x00007ff6a0452921 (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x2921)
#19 0x00007ff6a046063d (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x1063d)
#20 0x00007ff6a04510fe (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x10fe)
#21 0x00007ff6a04513b6 (G:\devenv\llvm-mingw-ucrt-x86_64\bin\clang-20.exe+0x13b6)
#22 0x00007ffc5f337374 (C:\Windows\System32\KERNEL32.DLL+0x17374)
#23 0x00007ffc5f47cc91 (C:\Windows\SYSTEM32\ntdll.dll+0x4cc91)
clang-20: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 20.1.7 (https://github.com/llvm/llvm-project.git 6146a88f60492b520a36f8f8f3231e15f3cc6082)
Target: x86_64-w64-windows-gnu
Thread model: posix

take from: https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/set-se-translator?view=msvc-170#example-catch-se_exception-error

#include <windows.h>
#include <eh.h>
#include <stdio.h>
#include <exception>

int thrower_func( int i ) {
   int y = 0;
   int *p = &y;
   *p = i / *p;
   return 0;
}

class SE_Exception : public std::exception
{
private:
    const unsigned int nSE;
public:
    SE_Exception() noexcept : SE_Exception{ 0 } {}
    SE_Exception( unsigned int n ) noexcept : nSE{ n } {}
    unsigned int getSeNumber() const noexcept { return nSE; }
};

class Scoped_SE_Translator
{
private:
    const _se_translator_function old_SE_translator;
public:
    Scoped_SE_Translator( _se_translator_function new_SE_translator ) noexcept
        : old_SE_translator{ _set_se_translator( new_SE_translator ) } {}
    ~Scoped_SE_Translator() noexcept { _set_se_translator( old_SE_translator ); }
};

#pragma unmanaged
void my_trans_func( unsigned int u, PEXCEPTION_POINTERS )
{
    throw SE_Exception( u );
}

void DoTest()
{
    try
    {
        thrower_func( 10 );
    }
    catch( const SE_Exception& e )
    {
        printf( "Caught SE_Exception, error %8.8x\n", e.getSeNumber() );
    }
    catch(...)
    {
        printf( "Caught unexpected SEH exception.\n" );
    }
}
#pragma managed

int main() {
    Scoped_SE_Translator scoped_se_translator{ my_trans_func };

    DoTest();
}

[mstorsjo]

The core here is that you're using -Xclang -fasync-exceptions - internal options enabled via -Xclang in cases where they're not supported, basically means that you're on your own.

The issue can be reduced down to a minimal repro:

struct exception {
  ~exception();
};
void my_trans_func() { exception(); }

This compiles fine in MSVC mode:

$ clang -target x86_64-windows-msvc -c repro.cpp -Xclang -fasync-exceptions

But fails in mingw mode:

$ clang -target x86_64-windows-gnu -c repro.cpp -Xclang -fasync-exceptions
clang: ../include/llvm/IR/BasicBlock.h:96: unsigned int llvm::BasicBlock::getNumber() const: Assertion `getParent() && "only basic blocks in functions have valid numbers"' failed.

Feel free to file an issue upstream at https://github.com/llvm/llvm-project/issues about it, but I doubt there'll be much effort spent on fixing it. The asynchronous exceptions mode is not very well supported overall, and there's probably no effort made to make it work in mingw mode.