CXXFLAGSΒΆ
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.