llvm/llvm-project

C++ Member pointer with module causing clang crash

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#167,638 opened on Nov 12, 2025

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clang:modulescrashhelp wantedplatform:windows

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Description

these code can reproduce the issue, using clang 21.1.5

module1

export module test;

export
struct foo{
	int v;
	int get() const noexcept{
		return v;
	}
};

module2

export module test_2;

import test;
import std;

export
void bar(){
	std::vector<foo> foos;
	[[maybe_unused]] auto itr = std::ranges::find(foos, 0, &foo::get);
}

main.cpp

import test_2;
import std;

int main() {
    bar();
}

Move the function bar into module test and import test; then the issue CANNOT be reproduced.

Both member pointer and member function pointer seem cause this issue.

My console output, conataining compile option

[  1%]: <mo_yanxi> generating.module.deps src\main.cpp
d:\lib\llvm\bin\clang-scan-deps.exe --format=p1689 -- D:\lib\LLVM\bin\clang++ -x c++ -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -c src\main.cpp -o build\.objs\mo_yanxi\windows\x64\debug\src\main.cpp.obj
[  1%]: <mo_yanxi> generating.module.deps src\test.ixx
d:\lib\llvm\bin\clang-scan-deps.exe --format=p1689 -- D:\lib\LLVM\bin\clang++ -x c++ -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -c src\test.ixx -o build\.objs\mo_yanxi\windows\x64\debug\src\test.ixx.obj
[ 25%]: <mo_yanxi> compiling.module.bmi.debug test
D:\lib\LLVM\bin\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -x c++-module --precompile -o build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\5df994ea6185f58f\test.pcm src\test.ixx
[ 34%]: <mo_yanxi> compiling.module.bmi.debug test_2
D:\lib\LLVM\bin\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -fmodule-file=std=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\af132e7790dc3ea1\std.pcm -fmodule-file=test=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\5df994ea6185f58f\test.pcm -x c++-module --precompile -o build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\effb05a9a0b27bb6\test_2.pcm src\test2.ixx
[ 43%]: compiling.debug src\test.ixx
D:\lib\LLVM\bin\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -o build\.objs\mo_yanxi\windows\x64\debug\src\test.ixx.obj build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\5df994ea6185f58f\test.pcm
[ 51%]: compiling.debug src\test2.ixx
D:\lib\LLVM\bin\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -fmodule-file=std=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\af132e7790dc3ea1\std.pcm -fmodule-file=test=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\5df994ea6185f58f\test.pcm -o build\.objs\mo_yanxi\windows\x64\debug\src\test2.ixx.obj build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\effb05a9a0b27bb6\test_2.pcm
[ 69%]: compiling.debug src\main.cpp
D:\lib\LLVM\bin\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -fmodule-file=std=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\af132e7790dc3ea1\std.pcm -fmodule-file=test_2=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\effb05a9a0b27bb6\test_2.pcm -fmodule-file=test=build\.gens\mo_yanxi\windows\x64\debug\rules\bmi\cache\interfaces\5df994ea6185f58f\test.pcm -o build\.objs\mo_yanxi\windows\x64\debug\src\main.cpp.obj src\main.cpp
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: D:\\lib\\LLVM\\bin\\clang++ -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -g -Wall -O0 -std=c++26 -fexceptions -fcxx-exceptions -finput-charset=UTF-8 -fexec-charset=UTF-8 -fmodule-file=std=build\\.gens\\mo_yanxi\\windows\\x64\\debug\\rules\\bmi\\cache\\interfaces\\af132e7790dc3ea1\\std.pcm -fmodule-file=test=build\\.gens\\mo_yanxi\\windows\\x64\\debug\\rules\\bmi\\cache\\interfaces\\5df994ea6185f58f\\test.pcm -fdiagnostics-color=always -o build\\.objs\\mo_yanxi\\windows\\x64\\debug\\src\\test2.ixx.obj build\\.gens\\mo_yanxi\\windows\\x64\\debug\\rules\\bmi\\cache\\interfaces\\effb05a9a0b27bb6\\test_2.pcm
1.      <eof> parser at end of file
2.      D:\projects\untitled\src\test2.ixx:7:6: LLVM IR generation of declaration 'bar'
3.      D:\projects\untitled\src\test2.ixx:7:6: Generating code for declaration 'bar'
Exception Code: 0xC0000005
 #0 0x00007ff766c084a7 (D:\lib\LLVM\bin\clang++.exe+0x17e84a7)
 #1 0x00007ff7654845df (D:\lib\LLVM\bin\clang++.exe+0x645df)
 #2 0x00007ff766e71201 (D:\lib\LLVM\bin\clang++.exe+0x1a51201)
 #3 0x00007ff766e8c5e4 (D:\lib\LLVM\bin\clang++.exe+0x1a6c5e4)
 #4 0x00007ff766e8ae89 (D:\lib\LLVM\bin\clang++.exe+0x1a6ae89)
 #5 0x00007ff766e86c01 (D:\lib\LLVM\bin\clang++.exe+0x1a66c01)
 #6 0x00007ff766e90bc9 (D:\lib\LLVM\bin\clang++.exe+0x1a70bc9)
 #7 0x00007ff766e7a1ac (D:\lib\LLVM\bin\clang++.exe+0x1a5a1ac)
 #8 0x00007ff7656f593e (D:\lib\LLVM\bin\clang++.exe+0x2d593e)
 #9 0x00007ff7656f564d (D:\lib\LLVM\bin\clang++.exe+0x2d564d)
#10 0x00007ff766e8cd3d (D:\lib\LLVM\bin\clang++.exe+0x1a6cd3d)
#11 0x00007ff766e8ced1 (D:\lib\LLVM\bin\clang++.exe+0x1a6ced1)
#12 0x00007ff766e8c965 (D:\lib\LLVM\bin\clang++.exe+0x1a6c965)
#13 0x00007ff76663a8a2 (D:\lib\LLVM\bin\clang++.exe+0x121a8a2)
#14 0x00007ff765430c6d (D:\lib\LLVM\bin\clang++.exe+0x10c6d)
#15 0x00007ff76542eefb (D:\lib\LLVM\bin\clang++.exe+0xeefb)
#16 0x00007ff7666328c9 (D:\lib\LLVM\bin\clang++.exe+0x12128c9)
#17 0x00007ff7666303ae (D:\lib\LLVM\bin\clang++.exe+0x12103ae)
#18 0x00007ff76662fefe (D:\lib\LLVM\bin\clang++.exe+0x120fefe)
#19 0x00007ff76662e515 (D:\lib\LLVM\bin\clang++.exe+0x120e515)
#20 0x00007ff76662bf4e (D:\lib\LLVM\bin\clang++.exe+0x120bf4e)
#21 0x00007ff76662b4cd (D:\lib\LLVM\bin\clang++.exe+0x120b4cd)
#22 0x00007ff766abef37 (D:\lib\LLVM\bin\clang++.exe+0x169ef37)
#23 0x00007ff766abbb12 (D:\lib\LLVM\bin\clang++.exe+0x169bb12)
#24 0x00007ff7673c0cbc (D:\lib\LLVM\bin\clang++.exe+0x1fa0cbc)
#25 0x00007ff7673b353f (D:\lib\LLVM\bin\clang++.exe+0x1f9353f)
#26 0x00007ff768a8fa80 (D:\lib\LLVM\bin\clang++.exe+0x366fa80)
#27 0x00007ff767d4d181 (D:\lib\LLVM\bin\clang++.exe+0x292d181)
#28 0x00007ff767359fa4 (D:\lib\LLVM\bin\clang++.exe+0x1f39fa4)
#29 0x00007ff765a4a493 (D:\lib\LLVM\bin\clang++.exe+0x62a493)
#30 0x00007ff765a4a0dd (D:\lib\LLVM\bin\clang++.exe+0x62a0dd)
#31 0x00007ff765a46d96 (D:\lib\LLVM\bin\clang++.exe+0x626d96)
#32 0x00007ff765a438f8 (D:\lib\LLVM\bin\clang++.exe+0x6238f8)
#33 0x00007ff765a4218e (D:\lib\LLVM\bin\clang++.exe+0x62218e)
#34 0x00007ff76632ee5d (D:\lib\LLVM\bin\clang++.exe+0xf0ee5d)
#35 0x00007ff765bd2685 (D:\lib\LLVM\bin\clang++.exe+0x7b2685)
#36 0x00007ff765bd2478 (D:\lib\LLVM\bin\clang++.exe+0x7b2478)
#37 0x00007ff7658f7825 (D:\lib\LLVM\bin\clang++.exe+0x4d7825)
#38 0x00007ff7658f716e (D:\lib\LLVM\bin\clang++.exe+0x4d716e)
#39 0x00007ff7658f6d4d (D:\lib\LLVM\bin\clang++.exe+0x4d6d4d)
#40 0x00007ff7658eda86 (D:\lib\LLVM\bin\clang++.exe+0x4cda86)
#41 0x00007ff7658eb023 (D:\lib\LLVM\bin\clang++.exe+0x4cb023)
#42 0x00007ff76740d0a0 (D:\lib\LLVM\bin\clang++.exe+0x1fed0a0)
#43 0x00007fff470ae8d7 (C:\WINDOWS\System32\KERNEL32.DLL+0x2e8d7)
#44 0x00007fff490cc53c (C:\WINDOWS\SYSTEM32\ntdll.dll+0x8c53c)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 21.1.5
Target: x86_64-unknown-windows-msvc
Thread model: posix
InstalledDir: D:\lib\LLVM\bin
clang++: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.

Contributor guide

Research direction
Investigate the code generation for member pointers across C++ module boundaries. Focus on the IR generation for std::ranges::find with member function pointer argument when the member function is defined in another module. Compare with the case where the function is in the same module to identify the cause of the crash.
Tech stack
cpp
Domain
tooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
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Over 1 week
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Active
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Clear
Prerequisites
GitC++
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