CFLAGS

Also known as CMAKE_C_FLAGS_RELEASE, CMAKE_C_FLAGS_DEBUG, -DCMAKE_C_FLAGS_DEBUG, -DCMAKE_C_FLAGS_RELEASE

CFLAGS and CXXFLAGS are either the name of environment variables or of Makefile variables that can be set to specify additional switches to be passed to a compiler in the process of building computer software. FFLAGS fulfills a similar role.