re PR target/65296 ([avr] fix various issues with specs file generation)

	PR target/65296
	* config/avr/driver-avr.c (avr_devicespecs_file): Don't specify a
	device specs file if "device-specs%s" didn't resolve to a path.

From-SVN: r221947

gcc/ChangeLog

+2015-04-09  Georg-Johann Lay  <avr@gjlay.de>
+
+	PR target/65296
+	* config/avr/driver-avr.c (avr_devicespecs_file): Don't specify a
+	device specs file if "device-specs%s" didn't resolve to a path.
+
 2015-04-09  Kirill Yukhin  <kirill.yukhin@intel.com>
 
 	PR target/65676

gcc/config/avr/driver-avr.c

@@ -80,6 +80,19 @@ avr_devicespecs_file (int argc, const char **argv)
       return X_NODEVLIB;
 
     case 1:
+      if (0 == strcmp ("device-specs", argv[0]))
+        {
+          /* FIXME:  This means "device-specs%s" from avr.h:DRIVER_SELF_SPECS
+             has not been resolved to a path.  That case can occur when the
+             c++ testsuite is run from the build directory.  DejaGNU's
+             libgloss.exp:get_multilibs runs $compiler without -B, i.e.runs
+             xgcc without specifying a prefix.  Without any prefix, there is
+             no means to find out where the specs files might be located.
+             get_multilibs runs xgcc --print-multi-lib, hence we don't actually
+             need information form a specs file and may skip it here.  */
+          return X_NODEVLIB;
+        }
+
       mmcu = AVR_MMCU_DEFAULT;
       break;