From a50f3f3218c618b4d68c5f58c6e1d59d2c84ca15 Mon Sep 17 00:00:00 2001
From: Alina Lenk <alina.v.lenk@gmail.com>
Date: Mon, 6 May 2024 17:20:48 +0200
Subject: [PATCH 2/2] Don't establish player contact via flagless units

See RM #558

Signed-off-by: Alina Lenk <alina.v.lenk@gmail.com>
---
 server/citytools.c |  2 +-
 server/plrhand.c   |  3 +++
 server/unithand.c  |  2 +-
 server/unittools.c | 23 ++++++++++++++++++++---
 server/unittools.h |  2 ++
 5 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/server/citytools.c b/server/citytools.c
index 24fc2bad71..aa416e31a1 100644
--- a/server/citytools.c
+++ b/server/citytools.c
@@ -689,7 +689,7 @@ static void transfer_unit(struct unit *punit, struct city *tocity,
       return;
     }
 
-    maybe_make_contact(utile, to_player);
+    unit_make_contact(punit, utile, to_player);
   }
   unit_change_homecity_handling(punit, tocity, rehome);
 }
diff --git a/server/plrhand.c b/server/plrhand.c
index 2ce80c4366..dcdb431a2d 100644
--- a/server/plrhand.c
+++ b/server/plrhand.c
@@ -2367,6 +2367,9 @@ void maybe_make_contact(struct tile *ptile, struct player *pplayer)
       make_contact(pplayer, city_owner(pcity), ptile);
     }
     unit_list_iterate_safe(tile1->units, punit) {
+      if (unit_has_type_flag(punit, UTYF_FLAGLESS)) {
+        continue; /* Flagless unit can't make contact */
+      }
       make_contact(pplayer, unit_owner(punit), ptile);
     } unit_list_iterate_safe_end;
   } square_iterate_end;
diff --git a/server/unithand.c b/server/unithand.c
index bbfeb3bf05..9e6ae577d9 100644
--- a/server/unithand.c
+++ b/server/unithand.c
@@ -3032,7 +3032,7 @@ static bool illegal_action_pay_price(struct player *pplayer,
        * distant target tile and maybe some contacts. */
       map_show_circle(pplayer, tgt_tile,
                       unit_type_get(act_unit)->vision_radius_sq);
-      maybe_make_contact(tgt_tile, pplayer);
+      unit_make_contact(act_unit, tgt_tile, pplayer);
     }
 
     if (act_unit->hp > 0) {
diff --git a/server/unittools.c b/server/unittools.c
index 5a00fd27d7..1978ba4f38 100644
--- a/server/unittools.c
+++ b/server/unittools.c
@@ -1736,7 +1736,7 @@ bool place_unit(struct unit *punit, struct player *pplayer,
 
   unit_list_prepend(pplayer->units, punit);
   unit_list_prepend(ptile->units, punit);
-  maybe_make_contact(ptile, unit_owner(punit));
+  unit_make_contact(punit, ptile, nullptr);
   if (pcity && !unit_has_type_flag(punit, UTYF_NOHOME)) {
     fc_assert(punit->homecity == pcity->id);
     fc_assert(city_owner(pcity) == pplayer);
@@ -3219,7 +3219,7 @@ bool do_paradrop(struct unit *punit, struct tile *ptile,
     char victim_link[MAX_LEN_LINK];
 
     map_show_circle(pplayer, ptile, act_utype->vision_radius_sq);
-    maybe_make_contact(ptile, pplayer);
+    unit_make_contact(punit, ptile, pplayer);
     notify_player(pplayer, ptile, E_UNIT_LOST_MISC, ftc_server,
                   _("Your %s was killed by enemy units at the "
                     "paradrop destination."),
@@ -4273,7 +4273,7 @@ bool unit_move(struct unit *punit, struct tile *pdesttile, int move_cost,
   if (unit_lives) {
     wakeup_neighbor_sentries(punit);
   }
-  maybe_make_contact(pdesttile, pplayer);
+  unit_make_contact(punit, pdesttile, pplayer);
 
   if (unit_lives) {
     /* Special checks for ground units in the ocean. */
@@ -5164,3 +5164,20 @@ void random_movements(struct player *pplayer)
 
   game.server.random_move_time = NULL;
 }
+
+/**********************************************************************//**
+  Make contact between a player and everyone adjacent to a tile via a unit
+  moving to that tile. Tile and player default to the unit's location and
+  owner if nullptr, but they may be different.
+**************************************************************************/
+void unit_make_contact(const struct unit *punit,
+                       struct tile *ptile, struct player *pplayer) {
+  fc_assert_ret(punit != nullptr);
+
+  if (unit_has_type_flag(punit, UTYF_FLAGLESS)) {
+    return; /* Flagless unit can't make contact */
+  }
+
+  maybe_make_contact(ptile ? ptile : unit_tile(punit),
+                     pplayer ? pplayer : unit_owner(punit));
+}
diff --git a/server/unittools.h b/server/unittools.h
index c2f8b60637..59acc4d0c3 100644
--- a/server/unittools.h
+++ b/server/unittools.h
@@ -124,6 +124,8 @@ void unit_assign_specific_activity_target(struct unit *punit,
                                           enum unit_activity *activity,
                                           struct extra_type **target);
 void unit_forget_last_activity(struct unit *punit);
+void unit_make_contact(const struct unit *punit,
+                       struct tile *ptile, struct player *pplayer);
 
 /* creation/deletion/upgrading */
 void transform_unit(struct unit *punit, const struct unit_type *to_unit,
-- 
2.34.1