Performing C++ SOURCE FILE Test MSGPACK_ENABLE_GCC_CXX_ATOMIC failed with the following output:
Change Dir: /home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_ac23e/fast && make[4]: Entering directory '/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_ac23e.dir/build.make CMakeFiles/cmTC_ac23e.dir/build
make[5]: Entering directory '/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_ac23e.dir/src.cxx.o
/home/user/librerouteros-C7/staging_dir/toolchain-mips_24kc_gcc-7.5.0_musl/bin/mips-openwrt-linux-musl-g++    -DMSGPACK_DEFAULT_API_VERSION=3 -std=c++98 -Os -pipe -mno-branch-likely -mips32r2 -mtune=24kc -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -msoft-float -mips16 -minterlink-mips16 -iremap/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0:msgpack-c-cpp-3.3.0 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -DMSGPACK_ENABLE_GCC_CXX_ATOMIC   -o CMakeFiles/cmTC_ac23e.dir/src.cxx.o -c /home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp/src.cxx
/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp/src.cxx:2:10: fatal error: bits/atomicity.h: No such file or directory
 #include <bits/atomicity.h>
          ^~~~~~~~~~~~~~~~~~
compilation terminated.
make[5]: *** [CMakeFiles/cmTC_ac23e.dir/build.make:66: CMakeFiles/cmTC_ac23e.dir/src.cxx.o] Error 1
make[5]: Leaving directory '/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp'
make[4]: *** [Makefile:121: cmTC_ac23e/fast] Error 2
make[4]: Leaving directory '/home/user/librerouteros-C7/build_dir/target-mips_24kc_musl/msgpack-c-cpp-3.3.0/CMakeFiles/CMakeTmp'


Source file was:

#include <bits/atomicity.h>
int atomic_sub(int i) { return __gnu_cxx::__exchange_and_add(&i, -1) - 1; }
int atomic_add(int i) { return __gnu_cxx::__exchange_and_add(&i, 1) + 1; }
int main(int argc, char * argv[])
{
    atomic_sub(1);
    atomic_add(1);
}