Move core.get_connected_players() implementation to C++

Keeping the ObjectRefs around in a table isn't ideal and this allows
removing the somewhat nonsensical is_player_connected() added in 86ef7147.

src/script/common/c_internal.h

@@ -103,5 +103,6 @@ int script_exception_wrapper(lua_State *L, lua_CFunction f);
 void script_error(lua_State *L, int pcall_result, const char *mod, const char *fxn);
 void script_run_callbacks_f(lua_State *L, int nargs,
 	RunCallbacksMode mode, const char *fxn);
+
 void log_deprecated(lua_State *L, const std::string &message,
 	int stack_depth=1);

src/script/lua_api/l_env.cpp

@@ -640,6 +640,23 @@ int ModApiEnvMod::l_add_item(lua_State *L)
 	return 1;
 }
 
+// get_connected_players()
+int ModApiEnvMod::l_get_connected_players(lua_State *L)
+{
+	GET_ENV_PTR;
+
+	lua_createtable(L, env->getPlayerCount(), 0);
+	u32 i = 0;
+	for (RemotePlayer *player : env->getPlayers()) {
+		PlayerSAO *sao = player->getPlayerSAO();
+		if (sao) {
+			getScriptApiBase(L)->objectrefGetOrCreate(L, sao);
+			lua_rawseti(L, -2, ++i);
+		}
+	}
+	return 1;
+}
+
 // get_player_by_name(name)
 int ModApiEnvMod::l_get_player_by_name(lua_State *L)
 {
@@ -647,7 +664,7 @@ int ModApiEnvMod::l_get_player_by_name(lua_State *L)
 
 	// Do it
 	const char *name = luaL_checkstring(L, 1);
-	RemotePlayer *player = dynamic_cast<RemotePlayer *>(env->getPlayer(name));
+	RemotePlayer *player = env->getPlayer(name);
 	if (player == NULL){
 		lua_pushnil(L);
 		return 1;
@@ -1319,6 +1336,7 @@ void ModApiEnvMod::Initialize(lua_State *L, int top)
 	API_FCT(find_nodes_with_meta);
 	API_FCT(get_meta);
 	API_FCT(get_node_timer);
+	API_FCT(get_connected_players);
 	API_FCT(get_player_by_name);
 	API_FCT(get_objects_inside_radius);
 	API_FCT(set_timeofday);

src/script/lua_api/l_env.h

@@ -101,6 +101,9 @@ private:
 	// pos = {x=num, y=num, z=num}
 	static int l_add_item(lua_State *L);
 
+	// get_connected_players()
+	static int l_get_connected_players(lua_State *L);
+
 	// get_player_by_name(name)
 	static int l_get_player_by_name(lua_State *L);
 

src/script/lua_api/l_object.cpp

@@ -1063,6 +1063,9 @@ int ObjectRef::l_get_luaentity(lua_State *L)
 int ObjectRef::l_is_player_connected(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
+	// This method was once added for a bugfix, but never documented
+	log_deprecated(L, "is_player_connected is undocumented and "
+		"will be removed in a future release");
 	ObjectRef *ref = checkobject(L, 1);
 	RemotePlayer *player = getplayer(ref);
 	lua_pushboolean(L, (player != NULL && player->getPeerId() != PEER_ID_INEXISTENT));

src/serverenvironment.h

@@ -358,6 +358,7 @@ public:
 
 	RemotePlayer *getPlayer(const session_t peer_id);
 	RemotePlayer *getPlayer(const char* name);
+	const std::vector<RemotePlayer *> getPlayers() const { return m_players; }
 	u32 getPlayerCount() const { return m_players.size(); }
 
 	static bool migratePlayersDatabase(const GameParams &game_params,