ninja: Entering directory `out/gn'
[1/3981] ACTION //libcxx/include:write_config_site(//llvm/utils/gn/build/toolchain:unix)
FAILED: include/c++/v1/__config_site 
python3 ../../llvm/utils/gn/build/write_cmake_config.py -o include/c++/v1/__config_site ../../libcxx/include/__config_site.in _LIBCPP_ABI_FORCE_ITANIUM= _LIBCPP_ABI_FORCE_MICROSOFT= _LIBCPP_ABI_VERSION=1 _LIBCPP_EXTRA_SITE_DEFINES= _LIBCPP_HAS_FILESYSTEM=1 _LIBCPP_HAS_THREADS=1 _LIBCPP_HAS_MONOTONIC_CLOCK=1 _LIBCPP_HAS_MUSL_LIBC= _LIBCPP_HAS_THREAD_API_PTHREAD= _LIBCPP_HAS_THREAD_API_EXTERNAL= _LIBCPP_HAS_THREAD_API_WIN32= _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS= _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS= _LIBCPP_NO_VCRUNTIME= _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION= _LIBCPP_HAS_RANDOM_DEVICE=1 _LIBCPP_HAS_LOCALIZATION=1 _LIBCPP_HAS_UNICODE=1 _LIBCPP_HAS_WIDE_CHARACTERS=1 _LIBCPP_HAS_TERMINAL=1 _LIBCPP_INSTRUMENTED_WITH_ASAN= _LIBCPP_ABI_DEFINES= _LIBCPP_HARDENING_MODE_DEFAULT=_LIBCPP_HARDENING_MODE_NONE _LIBCPP_PSTL_BACKEND_LIBDISPATCH= _LIBCPP_PSTL_BACKEND_SERIAL= _LIBCPP_PSTL_BACKEND_STD_THREAD=1 _LIBCPP_ABI_NAMESPACE=__1 _LIBCPP_HAS_TIME_ZONE_DATABASE=
Traceback (most recent call last):
  File "/Users/thakis/src/llvm-project/out/gn/../../llvm/utils/gn/build/write_cmake_config.py", line 122, in <module>
    sys.exit(main())
  File "/Users/thakis/src/llvm-project/out/gn/../../llvm/utils/gn/build/write_cmake_config.py", line 72, in main
    in_line = var_re.sub(repl, in_line)
  File "/Users/thakis/src/llvm-project/out/gn/../../llvm/utils/gn/build/write_cmake_config.py", line 70, in repl
    return values[key]
KeyError: '_LIBCPP_ASSERTION_SEMANTIC_DEFAULT'
[2/3981] AR lib/libclangAPINotes.a
[3/3981] ACTION //lld/wasm:Options(//llvm/utils/gn/build/toolchain:unix)
[4/3980] ACTION //lld/MinGW:Options(//llvm/utils/gn/build/toolchain:unix)
[5/3978] ACTION //lld/COFF:Options(//llvm/utils/gn/build/toolchain:unix)
[6/3964] ACTION //lld/ELF:Options(//llvm/utils/gn/build/toolchain:unix)
[7/3961] ACTION //lld/MachO:Options(//llvm/utils/gn/build/toolchain:unix)
[8/3961] AR lib/libclangDriver.a
[9/3961] ACTION //lldb/source/Interpreter:InterpreterProperties(//llvm/utils/gn/build/toolchain:unix)
[10/3961] ACTION //lldb/source/Commands:CommandOptions(//llvm/utils/gn/build/toolchain:unix)
ninja: build stopped: subcommand failed.
Command '['ninja', '-C', 'out/gn']' returned non-zero exit status 1.