updated for version 7.3.408
Problem:    Missing declaration.
Solution:   Add the declaration. (John Marriott)
diff --git a/src/gui_w48.c b/src/gui_w48.c
index 80fad9e..4d38c15 100644
--- a/src/gui_w48.c
+++ b/src/gui_w48.c
@@ -3286,6 +3286,7 @@
 {
     char_u *tmp;
     int len;
+    WCHAR *res;
 
     tmp = convert_filter(s);
     if (tmp == NULL)