-#if defined(PROCESSOR_CPU_LOAD_INFO) || defined(KERNEL_LINUX) || defined(HAVE_LIBKSTAT) || defined(HAVE_SYSCTLBYNAME)
-# define CPU_HAVE_READ 1
-#else
-# define CPU_HAVE_READ 0
+#if !PROCESSOR_CPU_LOAD_INFO && !KERNEL_LINUX && !HAVE_LIBKSTAT && !HAVE_SYSCTLBYNAME
+# error "No applicable input method."