function(check_lto) if (DEFINED LTO_WORKS) return() endif() set(LTO_WORKS FALSE CACHE INTERNAL "LTO works") CHECK_CXX_COMPILER_FLAG("-flto" HAS_LTO_FLAG) if (NOT HAS_LTO_FLAG) return() endif() find_program(LTO_AR NAMES "${CMAKE_C_COMPILER}-ar" gcc-ar) find_program(LTO_RANLIB NAMES "${CMAKE_C_COMPILER}-ranlib" gcc-ranlib) if (NOT LTO_AR OR NOT LTO_RANLIB) return() endif() EXECUTE_PROCESS(COMMAND "${LTO_AR}" --version RESULT_VARIABLE ret OUTPUT_QUIET ERROR_QUIET) if (ret) return() endif() EXECUTE_PROCESS(COMMAND "${LTO_RANLIB}" --version RESULT_VARIABLE ret OUTPUT_QUIET ERROR_QUIET) if (ret) return() endif() set(LTO_WORKS TRUE CACHE INTERNAL "LTO works") endfunction()