Add macro UNUSED to eliminate warnings about variables that are set to unused values

ChangeLog

@@ -7076,4 +7076,6 @@
 	* configs/sama5d3x-ek:  Change all configuration names to board-
 	  specific names so that this are no name collisions with other
 	  boards that have similar configuration variables (2013-3-30).
-
+	* configs/nuttx/compiler.h:  Add macro UNUSED() that can be used
+	  to eliminate warnings about variables that are set to values
+	  that are not used (2014-3-30).

drivers/mtd/ramtron.c

@@ -352,8 +352,8 @@ static inline int ramtron_readid(struct ramtron_dev_s *priv)
      
   if (priv->part->name)
     {
-      (void)manufacturer; /* Eliminate warnings when debug is off */
-      (void)memory;       /* Eliminate warnings when debug is off */
+      UNUSED(manufacturer); /* Eliminate warnings when debug is off */
+      UNUSED(memory);       /* Eliminate warnings when debug is off */
 
       fvdbg("RAMTRON %s of size %d bytes (mf:%02x mem:%02x cap:%02x part:%02x)\n",
             priv->part->name, priv->part->size, manufacturer, memory, capacity, part);

drivers/usbdev/usbmsc_scsi.c

@@ -391,6 +391,7 @@ static void usbmsc_scsi_wait(FAR struct usbmsc_dev_s *priv)
     {
       ret = sem_wait(&priv->thwaitsem);
       DEBUGASSERT(ret == OK || errno == EINTR);
+      UNUSED(ret); /* Eliminate warnings when debug is off */
     }
   while (priv->thwaiting);
 

include/nuttx/compiler.h

@@ -58,6 +58,10 @@
 # define CONFIG_HAVE_FUNCTIONNAME 1 /* Has __FUNCTION__ */
 # define CONFIG_HAVE_FILENAME     1 /* Has __FILE__ */
 
+/* Indicate that a local variable is not used */
+
+# define UNUSED(a) ((void)(a))
+
 /* Attributes
  *
  * GCC supports weak symbols which can be used to reduce code size because