Bug 952938 – llvm-runtimes/libcxxabi-20.1.1: Fails to build using 23.0/llvm profile

• Status: UNCONFIRMED
• Product: Gentoo Linux

[Description Pablo Cholaky 2025-03-30 21:07:56 UTC]

Hi there,

I got this issue since LLVM/Clang 20 was released into Gentoo and I have no idea where is the issue, if someone can lend a hand, very appreciated.

The error in question:

----
ld.lld: error: undefined symbol: _Unwind_Resume
>>> referenced by cxa_guard.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_guard.cpp.o:(__cxa_guard_acquire)
>>> referenced by cxa_vector.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_vector.cpp.o:(__cxa_vec_new)
>>> referenced by cxa_vector.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_vector.cpp.o:(__cxa_vec_new2)
>>> referenced 32 more times

ld.lld: error: undefined symbol: _Unwind_RaiseException
>>> referenced by cxa_exception.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_exception.cpp.o:(__cxa_throw)
>>> referenced by cxa_exception.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_exception.cpp.o:(__cxa_rethrow)
>>> referenced by cxa_exception.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_exception.cpp.o:(__cxa_rethrow_primary_exception)

ld.lld: error: undefined symbol: _Unwind_DeleteException
>>> referenced by cxa_exception.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_exception.cpp.o:(__cxa_end_catch)

ld.lld: error: undefined symbol: _Unwind_SetGR
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)
>>> referenced 1 more times

ld.lld: error: undefined symbol: _Unwind_SetIP
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)

ld.lld: error: undefined symbol: _Unwind_GetLanguageSpecificData
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)

ld.lld: error: undefined symbol: _Unwind_GetIP
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)

ld.lld: error: undefined symbol: _Unwind_GetRegionStart
>>> referenced by cxa_personality.cpp
>>>               libcxxabi/src/CMakeFiles/cxxabi_shared_objects.dir/cxa_personality.cpp.o:(__gxx_personality_v0)
i686-pc-linux-gnu-clang++: error: linker command failed with exit code 1 (use -v to see invocation)
----

I can build LLVM/Clang 19 and 20 (including libunwind 19 or 20) without any issue, same with GCC and any other package, but when I have build clang-runtime 20, it fails at libcxxabi 20 (libcxx 20 also fails with oneshot with undefined symbol _unwind errors)

Any ideas?

Reproducible: Always

Steps to Reproduce:
1. Have a system with LLVM+Clang 19
2. Build LLVM 20
3. Build Clang 20
4. Build Clang Runtime
Actual Results:  
Fails with several _Unwind symbols

Expected Results:  
Build fine

[Comment 1 Pablo Cholaky 2025-03-30 21:09:52 UTC]

Created attachment 923303 [details]
libcxxabi-20.1.1 Build log

[Comment 2 Pablo Cholaky 2025-03-30 21:10:41 UTC]

Created attachment 923304 [details]
Libcxx 20.1.1 Build Log - Using oneshot