CXXFLAGS — CMake 3.23.0-rc2 Documentation
cmake.org › cmake › helpThis is a CMake Environment Variable. Its initial value is taken from the calling process environment. Default compilation flags to be used when compiling CXX (C++) files. Will only be used by CMake on the first configuration to determine CXX default compilation flags, after which the value for CXXFLAGS is stored in the cache as CMAKE_CXX_FLAGS. For any configuration run ( including the first), the environment variable will be ignored if the CMAKE_CXX_FLAGS variable is defined.
CMAKE_<LANG>_FLAGS — CMake 3.23.0-rc3 Documentation
cmake.org › latest › variableFlags for all build types. <LANG> flags used regardless of the value of CMAKE_BUILD_TYPE. This is initialized for each language from environment variables: CMAKE_C_FLAGS : Initialized by the CFLAGS environment variable. CMAKE_CXX_FLAGS : Initialized by the CXXFLAGS environment variable. CMAKE_CUDA_FLAGS : Initialized by the CUDAFLAGS environment variable.