Ticket #18450: doing_it_wrong.18450.diff

wp-includes/rewrite.php

@@ -1857 +1857 @@
          * @param bool $hard Whether to update .htaccess (hard flush) or just update rewrite_rules option (soft flush). Default is true (hard).
          */
         function flush_rules($hard = true) {
+                if ( !did_action( 'admin_init' ) ) {
+                        _doing_it_wrong( __( 'Never flush rules before admin_init, and NEVER on a front-end page load! Do it on plugin activation instead.' ) );
+                        return false;
+                }
+
                 delete_option('rewrite_rules');
                 $this->wp_rewrite_rules();
                 if ( $hard && function_exists('save_mod_rewrite_rules') )