[Freeciv-Dev] Active Diplomat dumps core (with fix) (PR#1410)

["Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>]

The active diplomat code appears to assume old map_get_city() behaviour
that checks for unreal coordinates and returns NULL.

Needs a simple fix to do this explictly in caller code now (like many
other places, particularly those assuming sanity is stored in goto_dest
:-).

Cheers,
RossW
=====

 static void ai_manage_diplomat(struct player *pplayer, struct unit
*pdiplomat)
 {
   struct packet_diplomat_action dact;
-  struct city *ctarget, *pcity;
+  struct city *pcity, *ctarget = NULL;
   Unit_Type_id sanity = pdiplomat->id;
   bool broken_goto = FALSE;
 
   assert((pplayer != NULL) && (pdiplomat != NULL));
 
   /* Look for someone to bribe */
   broken_goto = ai_diplomat_bribe_nearby(pplayer, pdiplomat);
 
   /* Sanity check */
   if (find_unit_by_id(sanity) == NULL) { return; }
 
   /* If we are the only diplomat in a threatened city, stay to defend it. */
   pcity = map_get_city(pdiplomat->x, pdiplomat->y);
   if ((pcity != NULL)
       && (count_diplomats_on_tile(pdiplomat->x, pdiplomat->y) == 1)
       && ((pcity->ai.urgency > 0) || (pcity->ai.diplomat_threat))) {
     return;
   }
 
   /* Check if we can do the nasty diplomat stuff right now. */
-  ctarget = map_get_city(pdiplomat->goto_dest_x, pdiplomat->goto_dest_y);
+  if(normalize_map_pos(&pdiplomat->goto_dest_x, &pdiplomat->goto_dest_y)) {
+    ctarget = map_get_city(pdiplomat->goto_dest_x, pdiplomat->goto_dest_y);
#ifdef DEBUG
   freelog(LOG_DEBUG, "%s's diplomat %d aims for (%d,%d), and is at "
       "(%d,%d) with distance %d to %s (owned by %s)",
       pplayer->name, pdiplomat->id, 
       pdiplomat->goto_dest_x, pdiplomat->goto_dest_y, pdiplomat->x,
       pdiplomat->y, real_map_distance(pdiplomat->x, pdiplomat->y,
       pdiplomat->goto_dest_x, pdiplomat->goto_dest_y), ctarget ? 
       ctarget->name : "(none)", ctarget ? city_owner(ctarget)->name : "n/a");
 #endif
+  }
   if (ctarget && (real_map_distance(pdiplomat->x, pdiplomat->y,
       pdiplomat->goto_dest_x, pdiplomat->goto_dest_y) == 1) 
       && (pplayers_at_war(pplayer, city_owner(ctarget))