confdefs.h: Only one clock or timer configuration parameter can be defined

Only one of the following can be defined.

+ CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
+ CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER
+ CONFIGURE_APPLICATION_NEEDS_TIMER_DRIVER

Otherwise it is a configuration error which can be detected at
compilation time.

cpukit/sapi/include/confdefs.h

@@ -2611,7 +2611,8 @@ rtems_fs_init_functions_t    rtems_fs_init_helper =
   #endif
 #endif
 
-#ifndef RTEMS_SCHEDSIM
+#if !defined(RTEMS_SCHEDSIM)
+  #if !defined(CONFIGURE_HAS_OWN_DEVICE_DRIVER_TABLE)
     /*
      *  You must either explicity include or exclude the clock driver.
      *  It is such a common newbie error to leave it out.  Maybe this
@@ -2622,14 +2623,23 @@ rtems_fs_init_functions_t    rtems_fs_init_helper =
      *        drivers are assumed to use the same "timer" hardware
      *        on many boards.
      */
-#if !defined(CONFIGURE_HAS_OWN_DEVICE_DRIVER_TABLE)
     #if !defined(CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER) && \
         !defined(CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER) && \
         !defined(CONFIGURE_APPLICATION_NEEDS_TIMER_DRIVER)
       #error "CONFIGURATION ERROR: Do you want the clock driver or not?!?"
      #endif
+
+    /*
+     * Only one of the following three configuration parameters should be
+     * defined at a time.
+     */
+    #if ((defined(CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER) + \
+          defined(CONFIGURE_APPLICATION_NEEDS_TIMER_DRIVER) + \
+          defined(CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER)) > 1)
+       #error "CONFIGURATION ERROR: More than one clock/timer driver configuration parameter specified?!?"
     #endif
-#endif
+  #endif /* !defined(CONFIGURE_HAS_OWN_DEVICE_DRIVER_TABLE) */
+#endif   /* !defined(RTEMS_SCHEDSIM) */
 
 /*
  *  These names have been obsoleted so make the user application stop compiling