check_include_file("string.h" HAVE_STRING_H) find_package(Intl) add_library(getopt STATIC getopt.c getopt1.c) if(Intl_FOUND) target_include_directories(getopt PRIVATE ${Intl_INCLUDE_DIRS}) target_link_libraries(getopt PUBLIC ${Intl_LIBRARIES}) target_compile_definitions(getopt PRIVATE HAVE_LIBINTL_H) endif()