patch 7.4.2244

Problem:    Adding pattern to ":oldfiles" is not a generic solution.
Solution:   Add the ":filter /pat/ cmd" command modifier.  Only works for some
            commands right now.

src/message.c

@@ -137,6 +137,11 @@ msg_attr_keep(
     int		retval;
     char_u	*buf = NULL;
 
+    /* Skip messages not matching ":filter pattern".
+     * Don't filter when there is an error. */
+    if (!emsg_on_display && message_filtered(s))
+	return TRUE;
+
 #ifdef FEAT_EVAL
     if (attr == 0)
 	set_vim_var_string(VV_STATUSMSG, s, -1);
@@ -2149,6 +2154,17 @@ msg_puts_display(
     msg_check();
 }
 
+/*
+ * Return TRUE when ":filter pattern" was used and "msg" does not match
+ * "pattern".
+ */
+    int
+message_filtered(char_u *msg)
+{
+    return cmdmod.filter_regmatch.regprog != NULL
+		     && !vim_regexec(&cmdmod.filter_regmatch, msg, (colnr_T)0);
+}
+
 /*
  * Scroll the screen up one line for displaying the next message line.
  */