Index: /trunk/resources/data/validator/highway.mapcss
===================================================================
--- /trunk/resources/data/validator/highway.mapcss	(revision 17940)
+++ /trunk/resources/data/validator/highway.mapcss	(revision 17941)
@@ -189,2 +189,9 @@
   assertNoMatch: "way turn:lanes:forward=sharp_left;left|left;through;slight_right|slight_right;right";
 }
+
+/* #20442 traffic signals or similar on roundabouts */
+node[highway=traffic_signals                     ][ traffic_signals=signal] < way[highway][junction=roundabout],
+node[highway=~/^(traffic_signals|stop|give_way)$/][!traffic_signals       ] < way[highway][junction=roundabout] {
+  throwWarning: tr("{0} without right of way", "{1.tag}");
+  suggestAlternative: "junction=circular";
+}