[llvm-dev] libc++ failed to link against musl

[Dmitry Golovin via llvm-dev]

I'm trying to build LLVM, Clang, LLD, compiler-rt, libc++, libc++abi and libunwind with musl-based toolchain.

The configuration is the following:

     LIBCXX_HAS_MUSL_LIBC=ON
     LIBCXX_HAS_GCC_S_LIB=OFF
     CLANG_DEFAULT_CXX_STDLIB=libc++
     CLANG_DEFAULT_LINKER=lld
     CLANG_DEFAULT_RTLIB=compiler-rt
     LLVM_DEFAULT_TARGET_TRIPLE=x86_64-pc-linux-musl
     LLVM_TARGET_ARCH=x86_64
     LLVM_TARGETS_TO_BUILD=X86

When linking libc++.so there are a lot of undefined references to __cxa_allocate_exception, __cxa_begin_catch, __cxa_end_catch, __cxa_free_exception, __cxa_guard_abort, __cxa_guard_acquire, __cxa_guard_release, __cxa_pure_virtual, __cxa_rethrow, __cxa_throw, __gxx_personality_v0, _Unwind_Resume, vtable for __cxxabiv1::__class_type_info, vtable for __cxxabiv1::__si_class_type_info, vtable for __cxxabiv1::__vmi_class_type_info. The full output of the linking command is too long and is attached gzipped. The linking command is the following:

x86_64-linux-musl-g++ -fPIC -fPIC -fvisibility-inlines-hidden -Werror=date-time -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers  -Wno-long-long -Wno-maybe-uninitialized -Wdelete-non-virtual-dtor -Wno-comment -ffunction-sections -fdata-sections -O3  -Wl,-z,defs  -fPIC -nodefaultlibs -shared -Wl,-soname,libc++.so.1 -o lib/libc++.so.1.0 projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/algorithm.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/any.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/bind.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/chrono.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/condition_variable.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/debug.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/exception.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/functional.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/future.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/hash.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/ios.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/iostream.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/locale.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/memory.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/mutex.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/new.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/optional.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/random.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/regex.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/shared_mutex.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/stdexcept.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/string.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/strstream.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/system_error.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/thread.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/typeinfo.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/utility.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/valarray.cpp.o projects/libcxx/lib/CMakeFiles/cxx_objects.dir/__/src/variant.cpp.o  -lpthread -lc -lm -lrt

Please suggest how to fix these linking errors.

Regards,
Dmitry
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