[cfe-dev] Libcxx cmake warning "Host compiler must support std::atomic!"

[Krzysztof Parzyszek via cfe-dev]

I'm seeing the following warning during cmake. I'm not sure when it started. Is this a known issue? Can it be safely ignored?

CMake Warning at projects/libcxx/cmake/Modules/CheckLibcxxAtomic.cmake:49 (message):
  Host compiler must support std::atomic!
Call Stack (most recent call first):
  projects/libcxx/cmake/config-ix.cmake:63 (include)
  projects/libcxx/CMakeLists.txt:476 (include)

It's also showing up in the upstream bots:
http://lab.llvm.org:8011/builders/libcxx-libcxxabi-x86_64-linux-debian/builds/1189/steps/cmake/logs/stdio

The linker errors (in my cmake) are actually:
CMakeFiles/cmTC_354e0.dir/src.cxx.o: In function `__clang_call_terminate':
src.cxx:(.text.__clang_call_terminate[__clang_call_terminate]+0x2): undefined reference to `__cxa_begin_catch'
src.cxx:(.text.__clang_call_terminate[__clang_call_terminate]+0xb): undefined reference to `std::terminate()'
CMakeFiles/cmTC_354e0.dir/src.cxx.o:(.data.DW.ref.__gxx_personality_v0[DW.ref.__gxx_personality_v0]+0x0): undefined reference to `__gxx_personality_v0'
clang-8: error: linker command failed with exit code 1 (use -v to see invocation)
CMakeFiles/cmTC_354e0.dir/build.make:97: recipe for target 'cmTC_354e0' failed

-- 
Krzysztof Parzyszek  kparzysz at quicinc.com   LLVM compiler development