Add: Setting to save a unique id for each savegame

src/genworld.cpp

@@ -105,6 +105,11 @@ static void _GenerateWorld(void *)
 		/* Set the Random() seed to generation_seed so we produce the same map with the same seed */
 		if (_settings_game.game_creation.generation_seed == GENERATE_NEW_SEED) _settings_game.game_creation.generation_seed = _settings_newgame.game_creation.generation_seed = InteractiveRandom();
 		_random.SetSeed(_settings_game.game_creation.generation_seed);
+
+		/* Generates a unique id for the savegame, to avoid accidentally overwriting a save */
+		/* We keep id 0 for old savegames that don't have an id */
+		_settings_game.game_creation.generation_unique_id = _interactive_random.Next(UINT32_MAX - 1) + 1; /* Generates between [1,UINT32_MAX] */
+
 		SetGeneratingWorldProgress(GWP_MAP_INIT, 2);
 		SetObjectToPlace(SPR_CURSOR_ZZZ, PAL_NONE, HT_NONE, WC_MAIN_WINDOW, 0);
 

src/saveload/afterload.cpp

@@ -3045,6 +3045,12 @@ bool AfterLoadGame()
 		}
 	}
 
+	if (IsSavegameVersionBefore(203)) {
+		/* Generate a random id for savegames that didn't have one */
+		/* We keep id 0 for old savegames that don't have an id */
+		_settings_game.game_creation.generation_unique_id = _interactive_random.Next(UINT32_MAX-1) + 1; /* Generates between [1;UINT32_MAX] */
+	}
+
 	/* Station acceptance is some kind of cache */
 	if (IsSavegameVersionBefore(127)) {
 		Station *st;

src/saveload/saveload.cpp

@@ -270,8 +270,9 @@
  *  200   #6805   Extend railtypes to 64, adding uint16 to map array.
  *  201   #6885   Extend NewGRF persistant storages.
  *  202   #6867   Increase industry cargo slots to 16 in, 16 out
+ *  203   #6973   Add unique id to savegames
  */
-extern const uint16 SAVEGAME_VERSION = 202; ///< Current savegame version of OpenTTD.
+extern const uint16 SAVEGAME_VERSION = 203; ///< Current savegame version of OpenTTD.
 
 SavegameType _savegame_type; ///< type of savegame we are loading
 FileToSaveLoad _file_to_saveload; ///< File to save or load in the openttd loop.

src/settings_type.h

@@ -283,6 +283,7 @@ struct NetworkSettings {
 /** Settings related to the creation of games. */
 struct GameCreationSettings {
 	uint32 generation_seed;                  ///< noise seed for world generation
+	uint32 generation_unique_id;             ///< random id to differentiate savegames
 	Year   starting_year;                    ///< starting date
 	uint8  map_x;                            ///< X size of map
 	uint8  map_y;                            ///< Y size of map

src/table/settings.ini

@@ -2208,6 +2208,15 @@ min      = 0
 max      = UINT32_MAX
 cat      = SC_EXPERT
 
+[SDT_VAR]
+base     = GameSettings
+var      = game_creation.generation_unique_id
+type     = SLE_UINT32
+from     = 203
+def      = 0
+min      = 0
+max      = UINT32_MAX
+
 [SDT_VAR]
 base     = GameSettings
 var      = game_creation.tree_placer