stdarg processing bug

optional output arg fubar

TODO

@@ -1,10 +1,7 @@
-- bandjoin is still broken
+- vips im_copy_set /home/john/GIT/nip2/test/tmp/t1.v
+  /home/john/GIT/nip2/test/tmp/cmyk.v 15 1 1 0 0
 
-running test_formats.sh:
-
-VIPS-WARNING **: object.c:763: VipsEmbed can't assign 'extend' after construct
-/home/john/GIT/nip2/test/scripts/test_formats.sh: line 16: 25707
-Trace/breakpoint trap   vips im_bandjoin $image $tmp/mono.v $tmp/t1.v
+  VIPS-WARNING **: object.c:775: VipsImage can only assign 'xoffset' once
 
 
 

libvips/iofuncs/operation.c

@@ -411,11 +411,15 @@ vips_operation_get_valist_optional( VipsOperation *operation, va_list ap )
 
 		VIPS_OPERATION_COLLECT_SET( pspec, argument_class, ap );
 
-		g_object_set_property( G_OBJECT( operation ), 
-			name, &value );
+		/* We must collect input args as we walk the name/value list,
+		 * but we don't do anything with them.
+		 */
 
 		VIPS_OPERATION_COLLECT_GET( pspec, argument_class, ap );
 
+		/* Here's an output arg.
+		 */
+
 #ifdef VIPS_DEBUG
 		printf( "\twriting %s to %p\n", 
 			g_param_spec_get_name( pspec ), arg );