clang frontend crash with exit code 139 when using modules with stdexec

### system info:
- CachyOS
- clang 22.1.8
- gcc 16.2.1
- xmake v3.1.1

### clang version:
```
❯ clang -v
clang version 22.1.8
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-pc-linux-gnu/15.3.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-pc-linux-gnu/16
Found candidate GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/15.3.0
Found candidate GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/16
Selected GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/16
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
Found CUDA installation: /opt/cuda, version
Found HIP installation: /opt/rocm, version 3.5.0
```

### gcc version:
```
❯ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/16/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --enable-languages=ada,c,c++,d,fortran,go,lto,m2,objc,obj-c++,rust,cobol --enable-bootstrap --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://github.com/CachyOS/CachyOS-PKGBUILDS/issues --with-build-config=bootstrap-lto --with-gcc-major-version-only --with-linker-hash-style=gnu --with-system-zlib --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-libstdcxx-backtrace --enable-link-serialization=1 --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-fixincludes --disable-libssp --disable-libstdcxx-pch --disable-werror
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.2.1 20260810 (GCC)
```

### crash logs :
```
❯ rm -rf .xmake .cache build
❯ xmake config --toolchain=clang
checking for platform ... linux (x86_64)
note: install or modify (m) these packages (pass -y to skip confirm)?
in xmake-repo:
-> stdexec 2026.07.06 [license:Apache-2.0]
please input: y (y/n/m)

=> install stdexec 2026.07.06 .. ok
❯ xmake -v
checking for flags (-fvisibility-inlines-hidden) ... ok
checking for flags (-O3) ... ok
checking for flags (-std=c++26) ... ok
checking for flags (-DNDEBUG) ... ok
[ 0%]: generating.module.deps src/implementation.cpp
checking for /usr/bin/clang-scan-deps ... ok
/usr/bin/clang-scan-deps --format=p1689 -- /usr/bin/clang++ -x c++ -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -c src/implementation.cpp -o build/.objs/test/linux/x86_64/release/src/implementation.cpp.o
[ 0%]: generating.module.deps src/interface.cpp
/usr/bin/clang-scan-deps --format=p1689 -- /usr/bin/clang++ -x c++ -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -c src/interface.cpp -o build/.objs/test/linux/x86_64/release/src/interface.cpp.o
[ 0%]: generating.module.deps src/main.cpp
/usr/bin/clang-scan-deps --format=p1689 -- /usr/bin/clang++ -x c++ -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -c src/main.cpp -o build/.objs/test/linux/x86_64/release/src/main.cpp.o
[ 0%]: generating.module.deps /usr/include/c++/16/bits/std.cc
/usr/bin/clang-scan-deps --format=p1689 -- /usr/bin/clang++ -x c++ -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -c /usr/include/c++/16/bits/std.cc -o build/.objs/test/linux/x86_64/release/usr/include/c++/16/bits/std.cc.o
[ 0%]: generating.module.deps /usr/include/c++/16/bits/std.compat.cc
/usr/bin/clang-scan-deps --format=p1689 -- /usr/bin/clang++ -x c++ -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -c /usr/include/c++/16/bits/std.compat.cc -o build/.objs/test/linux/x86_64/release/usr/include/c++/16/bits/std.compat.cc.o
checking for flags (clang_module_file) ... ok
checking for flags (clang_modules_reduced_bmi) ... ok
checking for flags (clang_module_output) ... ok
[ 8%]: compiling.module.bmi.release interface
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -x c++-module --precompile -o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/17fd3cadf5e23b17/interface.pcm src/interface.cpp
[ 8%]: compiling.module.bmi.release std
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -x c++-module --precompile -Wno-include-angled-in-module-purview -Wno-reserved-module-identifier -Wno-deprecated-declarations -o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/e9968aa214a321aa/std.pcm /usr/include/c++/16/bits/std.cc
[ 25%]: compiling.module.bmi.release implementation
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -fmodule-file=interface=build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/17fd3cadf5e23b17/interface.pcm -x c++-module --precompile -o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/371357a6c3f29794/implementation.pcm src/implementation.cpp
[ 34%]: compiling.release /usr/include/c++/16/bits/std.cc
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -Wno-include-angled-in-module-purview -Wno-reserved-module-identifier -Wno-deprecated-declarations -o build/.objs/test/linux/x86_64/release/usr/include/c++/16/bits/std.cc.o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/e9968aa214a321aa/std.pcm
[ 34%]: compiling.release src/implementation.cpp
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -fmodule-file=interface=build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/17fd3cadf5e23b17/interface.pcm -o build/.objs/test/linux/x86_64/release/src/implementation.cpp.o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/371357a6c3f29794/implementation.pcm
[ 43%]: compiling.release src/main.cpp
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -o build/.objs/test/linux/x86_64/release/src/main.cpp.o src/main.cpp
checking for flags (-MMD -MF) ... ok
[ 43%]: compiling.release src/interface.cpp
/usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -o build/.objs/test/linux/x86_64/release/src/interface.cpp.o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/17fd3cadf5e23b17/interface.pcm
create ok!
compile_commands.json updated!
error: PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: /usr/bin/clang++ -c -Qunused-arguments -m64 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -O3 -std=c++26 -isystem /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include -DNDEBUG -fmodule-file=interface=build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/17fd3cadf5e23b17/interface.pcm -fdiagnostics-color=always -o build/.objs/test/linux/x86_64/release/src/implementation.cpp.o build/.gens/test/linux/x86_64/release/rules/bmi/cache/interfaces/371357a6c3f29794/implementation.pcm
1. parser at end of file
2. Per-file LLVM IR generation
3. /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include/exec/../stdexec/__detail/__task.hpp:420:26: Generating code for declaration 'stdexec::task::__awaiter_base::__awaiter_base'
4. /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include/exec/../stdexec/__detail/__task.hpp:427:7: LLVM IR generation of compound statement ('{}')
5. /mnt/RootVerse/foosfs/build/.packages/s/stdexec/2026.07.06/ab18b9ce4cd3416f9b75d5e82d3be6df/include/exec/../stdexec/__detail/__task.hpp:440:9: LLVM IR generation of compound statement ('{}')
#0 0x00007fb2d7d9143a llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/libLLVM.so.22.1+0x839143a)
#1 0x00007fb2d7d911cb llvm::sys::CleanupOnSignal(unsigned long) (/usr/lib/libLLVM.so.22.1+0x83911cb)
#2 0x00007fb2d7d46b40 (/usr/lib/libLLVM.so.22.1+0x8346b40)
#3 0x00007fb2d7d46d5d (/usr/lib/libLLVM.so.22.1+0x8346d5d)
#4 0x00007fb2cf244e70 (/usr/lib/libc.so.6+0x44e70)
#5 0x00007fb2d639acc4 llvm::Type::isIntegerTy(unsigned int) const (/usr/lib/libLLVM.so.22.1+0x699acc4)
#6 0x00007fb2d996ea3d clang::CodeGen::CodeGenTypes::ConvertTypeForMem(clang::QualType) (/usr/lib/libclang-cpp.so.22.1+0xf6ea3d)
#7 0x00007fb2da2b97f0 (/usr/lib/libclang-cpp.so.22.1+0x18b97f0)
#8 0x00007fb2da2b9406 clang::CodeGen::CodeGenFunction::EmitCallExprLValue(clang::CallExpr const*, llvm::CallBase**) (/usr/lib/libclang-cpp.so.22.1+0x18b9406)
#9 0x00007fb2d9c2d799 (/usr/lib/libclang-cpp.so.22.1+0x122d799)
#10 0x00007fb2d9c2d3d4 clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/usr/lib/libclang-cpp.so.22.1+0x122d3d4)
#11 0x00007fb2d9c2d9fc (/usr/lib/libclang-cpp.so.22.1+0x122d9fc)
#12 0x00007fb2d9dd88e7 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef) (/usr/lib/libclang-cpp.so.22.1+0x13d88e7)
#13 0x00007fb2d9dd875d clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef) (/usr/lib/libclang-cpp.so.22.1+0x13d875d)
#14 0x00007fb2d9dcaec0 clang::CodeGen::CodeGenFunction::EmitIfStmt(clang::IfStmt const&) (/usr/lib/libclang-cpp.so.22.1+0x13caec0)
#15 0x00007fb2d9dd87d4 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef) (/usr/lib/libclang-cpp.so.22.1+0x13d87d4)
#16 0x00007fb2d9dd875d clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef) (/usr/lib/libclang-cpp.so.22.1+0x13d875d)
#17 0x00007fb2da048a6b clang::CodeGen::CodeGenFunction::EmitConstructorBody(clang::CodeGen::FunctionArgList&) (/usr/lib/libclang-cpp.so.22.1+0x1648a6b)
#18 0x00007fb2d9dd65e8 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/usr/lib/libclang-cpp.so.22.1+0x13d65e8)
#19 0x00007fb2da29c182 clang::CodeGen::CodeGenModule::codegenCXXStructor(clang::GlobalDecl) (/usr/lib/libclang-cpp.so.22.1+0x189c182)
#20 0x00007fb2da29bc48 (/usr/lib/libclang-cpp.so.22.1+0x189bc48)
#21 0x00007fb2da2acfb8 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib/libclang-cpp.so.22.1+0x18acfb8)
#22 0x00007fb2d9adc26f clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc26f)
#23 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#24 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#25 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#26 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#27 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#28 0x00007fb2d9adc2b9 clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib/libclang-cpp.so.22.1+0x10dc2b9)
#29 0x00007fb2d9adc540 clang::CodeGen::CodeGenModule::Release() (/usr/lib/libclang-cpp.so.22.1+0x10dc540)
#30 0x00007fb2d9adc480 (/usr/lib/libclang-cpp.so.22.1+0x10dc480)
#31 0x00007fb2da0bf3c1 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/usr/lib/libclang-cpp.so.22.1+0x16bf3c1)
#32 0x00007fb2d9ba51c8 clang::ParseAST(clang::Sema&, bool, bool) (/usr/lib/libclang-cpp.so.22.1+0x11a51c8)
#33 0x00007fb2d9e87dfe clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/usr/lib/libclang-cpp.so.22.1+0x1487dfe)
#34 0x00007fb2d9e8758a clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib/libclang-cpp.so.22.1+0x148758a)
#35 0x000055c7df10a280 cc1_main(llvm::ArrayRef, char const*, void*) (/usr/bin/clang+++0x11280)
#36 0x000055c7df109679 (/usr/bin/clang+++0x10679)
#37 0x000055c7df109556 (/usr/bin/clang+++0x10556)
#38 0x00007fb2db56721d (/usr/lib/libclang-cpp.so.22.1+0x2b6721d)
#39 0x00007fb2d7d46ada llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/usr/lib/libLLVM.so.22.1+0x8346ada)
#40 0x00007fb2da185bb2 clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (/usr/lib/libclang-cpp.so.22.1+0x1785bb2)
#41 0x00007fb2da06e4ff clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/usr/lib/libclang-cpp.so.22.1+0x166e4ff)
#42 0x00007fb2da06de92 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/usr/lib/libclang-cpp.so.22.1+0x166de92)
#43 0x000055c7df1080f9 clang_main(int, char**, llvm::ToolContext const&) (/usr/bin/clang+++0xf0f9)
#44 0x000055c7df10754b main (/usr/bin/clang+++0xe54b)
#45 0x00007fb2cf227d0e (/usr/lib/libc.so.6+0x27d0e)
#46 0x00007fb2cf227e4b __libc_start_main (/usr/lib/libc.so.6+0x27e4b)
#47 0x000055c7df10d1d5 _start (/usr/bin/clang+++0x141d5)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
clang version 22.1.8
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang++: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.
```

### minimal reproducible example :
`clang++: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.` -- so i coudnt get any preprocessed source to attach.

interface.cpp :
```cpp
module;

#include

export module interface;

export struct interface_t
{
virtual auto foo() -> stdexec::task
{
co_return false;
}

virtual ~interface_t() = default;
};
```

implementation.cpp :
```cpp
module;

#include

export module implementation;

import interface;

auto bar() -> stdexec::task
{
co_return true;
}

export struct implementation_t : public interface_t
{
auto foo() -> stdexec::task override
{
bool result = co_await bar();
co_return result;
}
};
```

This code crashes both clang and gcc compilers. The issue seems to happen only when using modules with stdexec, normal header based code compiles fine.

**Download minimal xmake project:** [clang_crasher.zip](https://github.com/user-attachments/files/32205121/clang_crasher.zip)

**For clean compiling:**
- cd to extracted code folder
- `rm -rf .xmake .cache build`
- `xmake config --toolchain=clang -v` (or `--toolchain=gcc` for testing gcc)
- `xmake -v` to build

Start by reproducing the reported clang++ command using the generated interface.pcm and implementation.pcm files, then inspect the crash path in stdexec/__detail/__task.hpp around lines 420-440. The stack points to LLVM IR generation and CodeGenTypes::ConvertTypeForMem; done means the same modules build no longer cause clang to crash with exit code 139.

Written by the indexing model from the issue text.