CMAKE_COMPILER_IS_GNU<LANG>

True if the compiler is GNU.

If the selected <LANG> compiler is the GNU compiler then this is TRUE, if not it is FALSE. Unlike the other per-language variables, this uses the GNU syntax for identifying languages instead of the CMake syntax. Recognized values of the <LANG> suffix are:

CC = C compiler
CXX = C++ compiler
G77 = Fortran compiler