Use config::clear over assignment to default-constructed object

src/ai/configuration.cpp

@@ -48,7 +48,7 @@ void configuration::init(const config &game_config)
 	default_config_ = ais.child("default_config");
 	if (!default_config_) {
 		ERR_AI_CONFIGURATION << "Missing AI [default_config]. Therefore, default_config_ set to empty." << std::endl;
-		default_config_ = config();
+		default_config_.clear();
 	}
 
 
@@ -180,7 +180,7 @@ bool configuration::parse_side_config(side_number side, const config& original_c
 	LOG_AI_CONFIGURATION << "side "<< side <<": parsing AI configuration from config" << std::endl;
 
 	//leave only the [ai] children
-	cfg = config();
+	cfg.clear();
 	for (const config &aiparam : original_cfg.child_range("ai")) {
 		cfg.add_child("ai",aiparam);
 	}

src/carryover.cpp

@@ -224,7 +224,7 @@ void carryover_info::transfer_to(config& level)
 	}
 
 	next_scenario_ = "";
-	variables_ = config();
+	variables_.clear();
 	wml_menu_items_.clear();
 
 }

src/game_initialization/create_engine.cpp

@@ -156,8 +156,8 @@ random_map::random_map(const config& data)
 	, generator_name_(generate_whole_scenario_ ? data_["scenario_generation"] : data_["map_generation"])
 {
 	if(!data.has_child("generator")) {
-		data_ = config();
-		generator_data_= config();
+		data_.clear();
+		generator_data_.clear();
 		data_["description"] = "Error: Random map found with missing generator information. Scenario should have a [generator] child.";
 		data_["error_message"] = "missing [generator] tag";
 	} else {
@@ -165,8 +165,8 @@ random_map::random_map(const config& data)
 	}
 
 	if(!data.has_attribute("scenario_generation") && !data.has_attribute("map_generation")) {
-		data_ = config();
-		generator_data_= config();
+		data_.clear();
+		generator_data_.clear();
 		data_["description"] = "Error: Random map found with missing generator information. Scenario should have a [generator] child.";
 		data_["error_message"] = "couldn't find 'scenario_generation' or 'map_generation' attribute";
 	}

src/persist_var.cpp

@@ -108,7 +108,7 @@ static void set_global_variable(persist_context &ctx, const vconfig &pcfg)
 			}
 			catch(const invalid_variablename_exception&)
 			{
-				val = config();
+				val.clear();
 			}
 		} else {
 			for (size_t i = 0; i < arraylen; i++)

src/preferences/game.cpp

@@ -577,7 +577,7 @@ const config& options()
 		// It may be an invalid config, which would cause problems in
 		// multiplayer_create, so let's replace it with an empty but valid
 		// config
-		option_values = config();
+		option_values.clear();
 	} else {
 		option_values = preferences::get_child("options");
 	}

src/saved_game.cpp

@@ -243,7 +243,7 @@ void saved_game::expand_scenario()
 			set_defaults();
 		} else {
 			this->starting_pos_type_ = STARTINGPOS_INVALID;
-			this->starting_pos_ = config();
+			this->starting_pos_.clear();
 		}
 	}
 }
@@ -482,7 +482,7 @@ void saved_game::set_scenario(config scenario)
 void saved_game::remove_snapshot()
 {
 	this->starting_pos_type_ = STARTINGPOS_NONE;
-	this->starting_pos_ = config();
+	this->starting_pos_.clear();
 }
 
 config& saved_game::get_starting_pos()
@@ -523,7 +523,7 @@ void saved_game::convert_to_start_save()
 	has_carryover_expanded_ = false;
 
 	replay_data_ = replay_recorder_base();
-	replay_start_ = config();
+	replay_start_.clear();
 
 	remove_snapshot();
 }
@@ -643,14 +643,14 @@ void saved_game::set_data(config& cfg)
 		carryover_.swap(caryover_sides_start);
 		has_carryover_expanded_ = false;
 	} else {
-		carryover_ = config();
+		carryover_.clear();
 		has_carryover_expanded_ = false;
 	}
 
 	if(config& replay_start = cfg.child("replay_start")) {
 		replay_start_.swap(replay_start);
 	} else {
-		replay_start_ = config();
+		replay_start_.clear();
 	}
 
 	replay_data_ = replay_recorder_base();
@@ -670,7 +670,7 @@ void saved_game::set_data(config& cfg)
 		this->starting_pos_.swap(scenario);
 	} else {
 		this->starting_pos_type_ = STARTINGPOS_NONE;
-		this->starting_pos_ = config();
+		this->starting_pos_.clear();
 	}
 
 	LOG_NG << "scenario: '" << carryover_["next_scenario"].str() << "'\n";

src/tests/test_config.cpp

@@ -150,7 +150,7 @@ BOOST_AUTO_TEST_CASE ( test_config_attribute_value )
 		BOOST_CHECK_EQUAL(x_str, "123456789123");
 
 		// blank != "" test.
-	c = config();
+	c.clear();
 	BOOST_CHECK(!cc["x"].empty());
 	BOOST_CHECK(cc["x"].empty());
 	BOOST_CHECK(cc["x"].blank());

src/whiteboard/manager.cpp

@@ -619,7 +619,7 @@ void manager::send_network_data()
 		wb_cfg["side"] = static_cast<int>(team_index+1);
 		wb_cfg["to_sides"] = resources::gameboard->teams().at(team_index).allied_human_teams();
 
-		buf_cfg = config();
+		buf_cfg.clear();
 
 		resources::controller->send_to_wesnothd(packet, "whiteboard");