Code optimizations / refactor (#12704)

Co-authored-by: SmallJoker <SmallJoker@users.noreply.github.com>
Co-authored-by: sfan5 <sfan5@live.de>

src/client/camera.cpp

@@ -676,11 +676,12 @@ void Camera::drawNametags()
 			screen_pos.Y = screensize.Y *
 				(0.5 - transformed_pos[1] * zDiv * 0.5) - textsize.Height / 2;
 			core::rect<s32> size(0, 0, textsize.Width, textsize.Height);
-			core::rect<s32> bg_size(-2, 0, textsize.Width+2, textsize.Height);
 
 			auto bgcolor = nametag->getBgColor(m_show_nametag_backgrounds);
-			if (bgcolor.getAlpha() != 0)
+			if (bgcolor.getAlpha() != 0) {
+				core::rect<s32> bg_size(-2, 0, textsize.Width + 2, textsize.Height);
 				driver->draw2DRectangle(bgcolor, bg_size + screen_pos);
+			}
 
 			font->draw(
 				translate_string(utf8_to_wide(nametag->text)).c_str(),

src/client/clientlauncher.cpp

@@ -417,7 +417,7 @@ bool ClientLauncher::launch_game(std::string &error_message,
 		menudata.name                            = start_data.name;
 		menudata.password                        = start_data.password;
 		menudata.port                            = itos(start_data.socket_port);
-		menudata.script_data.errormessage        = error_message_lua;
+		menudata.script_data.errormessage        = std::move(error_message_lua);
 		menudata.script_data.reconnect_requested = reconnect_requested;
 
 		main_menu(&menudata);
@@ -582,8 +582,8 @@ void ClientLauncher::speed_tests()
 		TimeTaker timer("Testing std::string speed");
 		const u32 jj = 10000;
 		for (u32 j = 0; j < jj; j++) {
-			tempstring = "";
-			tempstring2 = "";
+			tempstring.clear();
+			tempstring2.clear();
 			const u32 ii = 10;
 			for (u32 i = 0; i < ii; i++) {
 				tempstring2 += "asd";

src/client/clientmap.cpp

@@ -840,8 +840,6 @@ void ClientMap::updateDrawListShadow(v3f shadow_light_pos, v3f shadow_light_dir,
 	v3s16 p_blocks_max;
 	getBlocksInViewRange(cam_pos_nodes, &p_blocks_min, &p_blocks_max, radius + length);
 
-	std::vector<v2s16> blocks_in_range;
-
 	for (auto &i : m_drawlist_shadow) {
 		MapBlock *block = i.second;
 		block->refDrop();

src/client/game.cpp

@@ -112,7 +112,7 @@ struct TextDestPlayerInventory : public TextDest
 	TextDestPlayerInventory(Client *client)
 	{
 		m_client = client;
-		m_formname = "";
+		m_formname.clear();
 	}
 	TextDestPlayerInventory(Client *client, const std::string &formname)
 	{
@@ -2985,14 +2985,15 @@ void Game::updateCamera(f32 dtime)
 	camera->update(player, dtime, tool_reload_ratio);
 	camera->step(dtime);
 
-	v3f camera_position = camera->getPosition();
-	v3f camera_direction = camera->getDirection();
 	f32 camera_fov = camera->getFovMax();
 	v3s16 camera_offset = camera->getOffset();
 
 	m_camera_offset_changed = (camera_offset != old_camera_offset);
 
 	if (!m_flags.disable_camera_update) {
+		v3f camera_position = camera->getPosition();
+		v3f camera_direction = camera->getDirection();
+
 		client->getEnv().getClientMap().updateCamera(camera_position,
 				camera_direction, camera_fov, camera_offset);
 
@@ -3149,7 +3150,7 @@ void Game::processPlayerInteraction(f32 dtime, bool show_hud)
 
 	runData.punching = false;
 
-	soundmaker->m_player_leftpunch_sound.name = "";
+	soundmaker->m_player_leftpunch_sound.name.clear();
 
 	// Prepare for repeating, unless we're not supposed to
 	if (isKeyDown(KeyType::PLACE) && !g_settings->getBool("safe_dig_and_place"))

src/client/hud.cpp

@@ -411,7 +411,7 @@ void Hud::drawLuaElements(const v3s16 &camera_offset)
 			case HUD_ELEM_WAYPOINT: {
 				if (!calculateScreenPos(camera_offset, e, &pos))
 					break;
-				v3f p_pos = player->getPosition() / BS;
+				
 				pos += v2s32(e->offset.X, e->offset.Y);
 				video::SColor color(255, (e->number >> 16) & 0xFF,
 										 (e->number >> 8)  & 0xFF,
@@ -429,6 +429,7 @@ void Hud::drawLuaElements(const v3s16 &camera_offset)
 				font->draw(text.c_str(), bounds + v2s32((e->align.X - 1.0) * bounds.getWidth() / 2, 0), color);
 				if (draw_precision) {
 					std::ostringstream os;
+					v3f p_pos = player->getPosition() / BS;
 					float distance = std::floor(precision * p_pos.getDistanceFrom(e->world_pos)) / precision;
 					os << distance << unit;
 					text = unescape_translate(utf8_to_wide(os.str()));

src/client/imagefilters.cpp

@@ -111,8 +111,6 @@ void imageCleanTransparent(video::IImage *src, u32 threshold)
 		if (bitmap.get(ctrx, ctry))
 			continue;
 
-		video::SColor c = src->getPixel(ctrx, ctry);
-
 		// Sample size and total weighted r, g, b values
 		u32 ss = 0, sr = 0, sg = 0, sb = 0;
 
@@ -137,6 +135,7 @@ void imageCleanTransparent(video::IImage *src, u32 threshold)
 
 		// Set pixel to average weighted by alpha
 		if (ss > 0) {
+			video::SColor c = src->getPixel(ctrx, ctry);
 			c.setRed(sr / ss);
 			c.setGreen(sg / ss);
 			c.setBlue(sb / ss);

src/client/keycode.cpp

@@ -332,7 +332,7 @@ KeyPress::KeyPress(const irr::SEvent::SKeyInput &in, bool prefer_character)
 		else
 			m_name = lookup_keychar(Char).Name;
 	} catch (UnknownKeycode &e) {
-		m_name = "";
+		m_name.clear();
 	};
 }
 

src/client/minimap.cpp

@@ -327,7 +327,7 @@ void Minimap::addMode(MinimapModeDef mode)
 	int zoom = -1;
 
 	// Build a default standard label
-	if (mode.label == "") {
+	if (mode.label.empty()) {
 		switch (mode.type) {
 			case MINIMAP_TYPE_OFF:
 				mode.label = gettext("Minimap hidden");
@@ -361,8 +361,8 @@ void Minimap::addMode(MinimapModeDef mode)
 	m_modes.push_back(mode);
 }
 
-void Minimap::addMode(MinimapType type, u16 size, std::string label,
-		std::string texture, u16 scale)
+void Minimap::addMode(MinimapType type, u16 size, const std::string &label,
+		const std::string &texture, u16 scale)
 {
 	MinimapModeDef mode;
 	mode.type = type;

src/client/minimap.h

@@ -130,8 +130,8 @@ public:
 
 	void clearModes() { m_modes.clear(); };
 	void addMode(MinimapModeDef mode);
-	void addMode(MinimapType type, u16 size = 0, std::string label = "",
-			std::string texture = "", u16 scale = 1);
+	void addMode(MinimapType type, u16 size = 0, const std::string &label = "",
+			const std::string &texture = "", u16 scale = 1);
 
 	void setModeIndex(size_t index);
 	size_t getModeIndex() const { return m_current_mode_index; };

src/client/shader.cpp

@@ -184,7 +184,7 @@ public:
 	ShaderCallback(const Factories &factories)
 	{
 		for (auto &&factory : factories)
-			m_setters.push_back(std::unique_ptr<IShaderConstantSetter>(factory->create()));
+			m_setters.emplace_back(factory->create());
 	}
 
 	virtual void OnSetConstants(video::IMaterialRendererServices *services, s32 userData) override
@@ -402,7 +402,7 @@ public:
 
 	void addShaderConstantSetterFactory(IShaderConstantSetterFactory *setter) override
 	{
-		m_setter_factories.push_back(std::unique_ptr<IShaderConstantSetterFactory>(setter));
+		m_setter_factories.emplace_back(setter);
 	}
 
 private:

src/client/sound_openal.cpp

@@ -409,7 +409,7 @@ public:
 		}
 		std::vector<SoundBuffer*> bufs;
 		bufs.push_back(buf);
-		m_buffers[name] = bufs;
+		m_buffers[name] = std::move(bufs);
 	}
 
 	SoundBuffer* getBuffer(const std::string &name)

src/client/tile.cpp

@@ -979,8 +979,9 @@ video::IImage* TextureSource::generateImage(const std::string &name)
 				<< std::endl;
 			return NULL;
 		}
-		core::dimension2d<u32> dim = tmp->getDimension();
+		
 		if (baseimg) {
+			core::dimension2d<u32> dim = tmp->getDimension();
 			blit_with_alpha(tmp, baseimg, v2s32(0, 0), v2s32(0, 0), dim);
 			tmp->drop();
 		} else {

src/content/mod_configuration.cpp

@@ -227,7 +227,7 @@ void ModConfiguration::resolveDependencies()
 
 	// Step 2: get dependencies (including optional dependencies)
 	// of each mod, split mods into satisfied and unsatisfied
-	std::list<ModSpec> satisfied;
+	std::vector<ModSpec> satisfied;
 	std::list<ModSpec> unsatisfied;
 	for (ModSpec mod : m_unsatisfied_mods) {
 		mod.unsatisfied_depends = mod.depends;

src/database/database-dummy.cpp

@@ -36,7 +36,7 @@ void Database_Dummy::loadBlock(const v3s16 &pos, std::string *block)
 	s64 i = getBlockAsInteger(pos);
 	auto it = m_database.find(i);
 	if (it == m_database.end()) {
-		*block = "";
+		block->clear();
 		return;
 	}
 

src/database/database-files.cpp

@@ -497,5 +497,5 @@ Json::Value *ModMetadataDatabaseFiles::getOrCreateJson(const std::string &modnam
 		}
 	}
 
-	return &(m_mod_meta[modname] = meta);
+	return &(m_mod_meta[modname] = std::move(meta));
 }

src/filesys.cpp

@@ -639,7 +639,7 @@ std::string RemoveLastPathComponent(const std::string &path,
 		std::string *removed, int count)
 {
 	if(removed)
-		*removed = "";
+		removed->clear();
 
 	size_t remaining = path.size();
 

src/gui/guiButton.cpp

@@ -329,10 +329,9 @@ void GUIButton::draw()
 
 	if (SpriteBank)
 	{
-		core::position2di pos(buttonCenter);
-
 		if (isEnabled())
 		{
+			core::position2di pos(buttonCenter);
 			// pressed / unpressed animation
 			EGUI_BUTTON_STATE state = Pressed ? EGBS_BUTTON_DOWN : EGBS_BUTTON_UP;
 			drawSprite(state, ClickTime, pos);

src/gui/guiEngine.cpp

@@ -195,7 +195,7 @@ GUIEngine::GUIEngine(JoystickController *joystick,
 
 	try {
 		m_script->setMainMenuData(&m_data->script_data);
-		m_data->script_data.errormessage = "";
+		m_data->script_data.errormessage.clear();
 
 		if (!loadMainMenuScript()) {
 			errorstream << "No future without main menu!" << std::endl;

src/gui/guiFormSpecMenu.cpp

@@ -694,7 +694,7 @@ void GUIFormSpecMenu::parseScrollBar(parserData* data, const std::string &elemen
 	e->setMax(max);
 	e->setMin(min);
 
-	e->setPos(stoi(parts[4]));
+	e->setPos(stoi(value));
 
 	e->setSmallStep(data->scrollbar_options.small_step);
 	e->setLargeStep(data->scrollbar_options.large_step);
@@ -1180,7 +1180,6 @@ void GUIFormSpecMenu::parseTable(parserData* data, const std::string &element)
 	std::string name = parts[2];
 	std::vector<std::string> items = split(parts[3],',');
 	std::string str_initial_selection;
-	std::string str_transparent = "false";
 
 	if (parts.size() >= 5)
 		str_initial_selection = parts[4];
@@ -2264,7 +2263,7 @@ void GUIFormSpecMenu::parseBackgroundColor(parserData* data, const std::string &
 	}
 
 	// bgcolor
-	if (parameter_count >= 1 && parts[0] != "")
+	if (parameter_count >= 1 && !parts[0].empty())
 		parseColorString(parts[0], m_bgcolor, false);
 
 	// fullscreen
@@ -2275,14 +2274,14 @@ void GUIFormSpecMenu::parseBackgroundColor(parserData* data, const std::string &
 		} else if (parts[1] == "neither") {
 			m_bgnonfullscreen = false;
 			m_bgfullscreen = false;
-		} else if (parts[1] != "" || m_formspec_version < 3) {
+		} else if (!parts[1].empty() || m_formspec_version < 3) {
 			m_bgfullscreen = is_yes(parts[1]);
 			m_bgnonfullscreen = !m_bgfullscreen;
 		}
 	}
 
 	// fbgcolor
-	if (parameter_count >= 3 && parts[2] != "")
+	if (parameter_count >= 3 && !parts[2].empty())
 		parseColorString(parts[2], m_fullscreen_bgcolor, false);
 }
 
@@ -3047,7 +3046,7 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 		}
 	} else {
 		// Don't keep old focus value
-		m_focused_element = "";
+		m_focused_element.clear();
 	}
 
 	// Remove children
@@ -3865,7 +3864,7 @@ void GUIFormSpecMenu::acceptInput(FormspecQuitMode quitmode)
 
 		if (!current_field_enter_pending.empty()) {
 			fields["key_enter_field"] = current_field_enter_pending;
-			current_field_enter_pending = "";
+			current_field_enter_pending.clear();
 		}
 
 		if (current_keys_pending.key_escape) {
@@ -4600,7 +4599,7 @@ bool GUIFormSpecMenu::OnEvent(const SEvent& event)
 				} else if (s.ftype == f_ScrollBar) {
 					s.fdefault = L"Changed";
 					acceptInput(quit_mode_no);
-					s.fdefault = L"";
+					s.fdefault.clear();
 				} else if (s.ftype == f_Unknown || s.ftype == f_HyperText) {
 					if (!s.sound.empty() && m_sound_manager)
 						m_sound_manager->playSound(SimpleSoundSpec(s.sound, 1.0f));

src/gui/guiScene.cpp

@@ -86,9 +86,10 @@ void GUIScene::draw()
 
 	core::rect<s32> oldViewPort = m_driver->getViewPort();
 	m_driver->setViewPort(getAbsoluteClippingRect());
-	core::recti borderRect = Environment->getRootGUIElement()->getAbsoluteClippingRect();
 
 	if (m_bgcolor != 0) {
+		core::recti borderRect =
+				Environment->getRootGUIElement()->getAbsoluteClippingRect();
 		Environment->getSkin()->draw3DSunkenPane(
 			this, m_bgcolor, false, true, borderRect, 0);
 	}

src/itemdef.cpp

@@ -99,14 +99,14 @@ void ItemDefinition::resetInitial()
 void ItemDefinition::reset()
 {
 	type = ITEM_NONE;
-	name = "";
-	description = "";
-	short_description = "";
-	inventory_image = "";
-	inventory_overlay = "";
-	wield_image = "";
-	wield_overlay = "";
-	palette_image = "";
+	name.clear();
+	description.clear();
+	short_description.clear();
+	inventory_image.clear();
+	inventory_overlay.clear();
+	wield_image.clear();
+	wield_overlay.clear();
+	palette_image.clear();
 	color = video::SColor(0xFFFFFFFF);
 	wield_scale = v3f(1.0, 1.0, 1.0);
 	stack_max = 99;
@@ -118,7 +118,7 @@ void ItemDefinition::reset()
 	sound_place = SimpleSoundSpec();
 	sound_place_failed = SimpleSoundSpec();
 	range = -1;
-	node_placement_prediction = "";
+	node_placement_prediction.clear();
 	place_param2 = 0;
 }
 
@@ -462,7 +462,7 @@ public:
 		//   "ignore" is the ignore node
 
 		ItemDefinition* hand_def = new ItemDefinition;
-		hand_def->name = "";
+		hand_def->name.clear();
 		hand_def->wield_image = "wieldhand.png";
 		hand_def->tool_capabilities = new ToolCapabilities;
 		m_item_definitions.insert(std::make_pair("", hand_def));

src/main.cpp

@@ -484,7 +484,7 @@ static bool setup_log_params(const Settings &cmd_args)
 			color_mode = color_mode_env;
 #endif
 	}
-	if (color_mode != "") {
+	if (!color_mode.empty()) {
 		if (color_mode == "auto") {
 			Logger::color_mode = LOG_COLOR_AUTO;
 		} else if (color_mode == "always") {
@@ -586,7 +586,7 @@ static void startup_message()
 static bool read_config_file(const Settings &cmd_args)
 {
 	// Path of configuration file in use
-	sanity_check(g_settings_path == "");	// Sanity check
+	sanity_check(g_settings_path.empty());	// Sanity check
 
 	if (cmd_args.exists("config")) {
 		bool r = g_settings->readConfigFile(cmd_args.get("config").c_str());
@@ -793,7 +793,7 @@ static bool auto_select_world(GameParams *game_params)
 		           << world_path << "]" << std::endl;
 	}
 
-	assert(world_path != "");	// Post-condition
+	assert(!world_path.empty());	// Post-condition
 	game_params->world_path = world_path;
 	return true;
 }
@@ -849,7 +849,7 @@ static bool determine_subgame(GameParams *game_params)
 {
 	SubgameSpec gamespec;
 
-	assert(game_params->world_path != "");	// Pre-condition
+	assert(!game_params->world_path.empty());	// Pre-condition
 
 	// If world doesn't exist
 	if (!game_params->world_path.empty()

src/map.cpp

@@ -533,7 +533,7 @@ void ServerMap::transformLiquids(std::map<v3s16, MapBlock*> &modified_blocks,
 		infostream<<"transformLiquids(): initial_size="<<initial_size<<std::endl;*/
 
 	// list of nodes that due to viscosity have not reached their max level height
-	std::deque<v3s16> must_reflow;
+	std::vector<v3s16> must_reflow;
 
 	std::vector<std::pair<v3s16, MapNode> > changed_nodes;
 
@@ -835,7 +835,7 @@ void ServerMap::transformLiquids(std::map<v3s16, MapBlock*> &modified_blocks,
 	}
 	//infostream<<"Map::transformLiquids(): loopcount="<<loopcount<<std::endl;
 
-	for (auto &iter : must_reflow)
+	for (const auto &iter : must_reflow)
 		m_transforming_liquid.push_back(iter);
 
 	voxalgo::update_lighting_nodes(this, changed_nodes, modified_blocks);

src/mapgen/mg_schematic.cpp

@@ -234,7 +234,6 @@ bool Schematic::placeOnVManip(MMVManip *vm, v3s16 p, u32 flags,
 void Schematic::placeOnMap(ServerMap *map, v3s16 p, u32 flags,
 	Rotation rot, bool force_place)
 {
-	std::map<v3s16, MapBlock *> lighting_modified_blocks;
 	std::map<v3s16, MapBlock *> modified_blocks;
 	std::map<v3s16, MapBlock *>::iterator it;
 

src/network/clientpackethandler.cpp

@@ -152,7 +152,7 @@ void Client::handleCommand_AuthAccept(NetworkPacket* pkt)
 	language code (e.g. "de" for German). */
 	std::string lang = gettext("LANG_CODE");
 	if (lang == "LANG_CODE")
-		lang = "";
+		lang.clear();
 
 	NetworkPacket resp_pkt(TOSERVER_INIT2, sizeof(u16) + lang.size());
 	resp_pkt << lang;

src/network/connection.cpp

@@ -64,7 +64,7 @@ BufferedPacketPtr makePacket(Address &address, const SharedBuffer<u8> &data,
 {
 	u32 packet_size = data.getSize() + BASE_HEADER_SIZE;
 
-	BufferedPacketPtr p(new BufferedPacket(packet_size));
+	auto p = std::make_shared<BufferedPacket>(packet_size);
 	p->address = address;
 
 	writeU32(&p->data[0], protocol_id);
@@ -492,10 +492,10 @@ SharedBuffer<u8> IncomingSplitBuffer::insert(BufferedPacketPtr &p_ptr, bool reli
 
 void IncomingSplitBuffer::removeUnreliableTimedOuts(float dtime, float timeout)
 {
-	std::deque<u16> remove_queue;
+	std::vector<u16> remove_queue;
 	{
 		MutexAutoLock listlock(m_map_mutex);
-		for (auto &i : m_buf) {
+		for (const auto &i : m_buf) {
 			IncomingSplitPacket *p = i.second;
 			// Reliable ones are not removed by timeout
 			if (p->reliable)

src/nodedef.cpp

@@ -354,12 +354,12 @@ void ContentFeatures::reset()
 		NOTE: Most of this is always overridden by the default values given
 		      in builtin.lua
 	*/
-	name = "";
+	name.clear();
 	groups.clear();
 	// Unknown nodes can be dug
 	groups["dig_immediate"] = 2;
 	drawtype = NDT_NORMAL;
-	mesh = "";
+	mesh.clear();
 #ifndef SERVER
 	for (auto &i : mesh_ptr)
 		i = NULL;
@@ -387,9 +387,9 @@ void ContentFeatures::reset()
 	leveled = 0;
 	leveled_max = LEVELED_MAX;
 	liquid_type = LIQUID_NONE;
-	liquid_alternative_flowing = "";
+	liquid_alternative_flowing.clear();
 	liquid_alternative_flowing_id = CONTENT_IGNORE;
-	liquid_alternative_source = "";
+	liquid_alternative_source.clear();
 	liquid_alternative_source_id = CONTENT_IGNORE;
 	liquid_viscosity = 0;
 	liquid_renewable = true;
@@ -410,7 +410,7 @@ void ContentFeatures::reset()
 	connects_to_ids.clear();
 	connect_sides = 0;
 	color = video::SColor(0xFFFFFFFF);
-	palette_name = "";
+	palette_name.clear();
 	palette = NULL;
 	node_dig_prediction = "air";
 	move_resistance = 0;
@@ -1355,7 +1355,7 @@ void NodeDefManager::eraseIdFromGroups(content_t id)
 content_t NodeDefManager::set(const std::string &name, const ContentFeatures &def)
 {
 	// Pre-conditions
-	assert(name != "");
+	assert(!name.empty());
 	assert(name != "ignore");
 	assert(name == def.name);
 
@@ -1395,7 +1395,7 @@ content_t NodeDefManager::set(const std::string &name, const ContentFeatures &de
 
 content_t NodeDefManager::allocateDummy(const std::string &name)
 {
-	assert(name != "");	// Pre-condition
+	assert(!name.empty());	// Pre-condition
 	ContentFeatures f;
 	f.name = name;
 	return set(name, f);
@@ -1405,7 +1405,7 @@ content_t NodeDefManager::allocateDummy(const std::string &name)
 void NodeDefManager::removeNode(const std::string &name)
 {
 	// Pre-condition
-	assert(name != "");
+	assert(!name.empty());
 
 	// Erase name from name ID mapping
 	content_t id = CONTENT_IGNORE;

src/nodetimer.h

@@ -93,15 +93,11 @@ public:
 		}
 	}
 	// Undefined behaviour if there already is a timer
-	void insert(NodeTimer timer) {
+	void insert(const NodeTimer &timer) {
 		v3s16 p = timer.position;
 		double trigger_time = m_time + (double)(timer.timeout - timer.elapsed);
-		std::multimap<double, NodeTimer>::iterator it =
-			m_timers.insert(std::pair<double, NodeTimer>(
-				trigger_time, timer
-			));
-		m_iterators.insert(
-			std::pair<v3s16, std::multimap<double, NodeTimer>::iterator>(p, it));
+		std::multimap<double, NodeTimer>::iterator it = m_timers.emplace(trigger_time, timer);
+		m_iterators.emplace(p, it);
 		if (m_next_trigger_time == -1. || trigger_time < m_next_trigger_time)
 			m_next_trigger_time = trigger_time;
 	}

src/script/common/c_content.cpp

@@ -481,7 +481,7 @@ TileDef read_tiledef(lua_State *L, int index, u8 drawtype)
 	else if(lua_istable(L, index))
 	{
 		// name="default_lava.png"
-		tiledef.name = "";
+		tiledef.name.clear();
 		getstringfield(L, index, "name", tiledef.name);
 		getstringfield(L, index, "image", tiledef.name); // MaterialSpec compat.
 		tiledef.backface_culling = getboolfield_default(

src/script/cpp_api/s_base.cpp

@@ -171,7 +171,7 @@ void ScriptApiBase::clientOpenLibs(lua_State *L)
 #endif
 	};
 
-	for (const std::pair<std::string, lua_CFunction> &lib : m_libs) {
+	for (const auto &lib : m_libs) {
 	    lua_pushcfunction(L, lib.second);
 	    lua_pushstring(L, lib.first.c_str());
 	    lua_call(L, 1, 0);

src/script/lua_api/l_client.cpp

@@ -237,7 +237,7 @@ int ModApiClient::l_get_language(lua_State *L)
 #endif
 	std::string lang = gettext("LANG_CODE");
 	if (lang == "LANG_CODE")
-		lang = "";
+		lang.clear();
 
 	lua_pushstring(L, locale);
 	lua_pushstring(L, lang.c_str());

src/script/lua_api/l_item.cpp

@@ -600,7 +600,7 @@ int ModApiItemMod::l_register_item_raw(lua_State *L)
 		if(def.type == ITEM_NODE)
 			def.node_placement_prediction = name;
 		else
-			def.node_placement_prediction = "";
+			def.node_placement_prediction.clear();
 	}
 
 	// Register item definition

src/server.cpp

@@ -424,7 +424,7 @@ void Server::init()
 	m_mod_storage_database->beginSave();
 
 	m_modmgr = std::make_unique<ServerModManager>(m_path_world);
-	std::vector<ModSpec> unsatisfied_mods = m_modmgr->getUnsatisfiedMods();
+
 	// complain about mods with unsatisfied dependencies
 	if (!m_modmgr->isConsistent()) {
 		std::string error = m_modmgr->getUnsatisfiedModsError();
@@ -1359,8 +1359,6 @@ void Server::Send(session_t peer_id, NetworkPacket *pkt)
 
 void Server::SendMovement(session_t peer_id)
 {
-	std::ostringstream os(std::ios_base::binary);
-
 	NetworkPacket pkt(TOCLIENT_MOVEMENT, 12 * sizeof(float), peer_id);
 
 	pkt << g_settings->getFloat("movement_acceleration_default");

src/tool.cpp

@@ -35,7 +35,7 @@ void ToolGroupCap::toJson(Json::Value &object) const
 	Json::Value times_object;
 	for (auto time : times)
 		times_object[time.first] = time.second;
-	object["times"] = times_object;
+	object["times"] = std::move(times_object);
 }
 
 void ToolGroupCap::fromJson(const Json::Value &json)
@@ -134,14 +134,13 @@ void ToolCapabilities::serializeJson(std::ostream &os) const
 	for (const auto &groupcap : groupcaps) {
 		groupcap.second.toJson(groupcaps_object[groupcap.first]);
 	}
-	root["groupcaps"] = groupcaps_object;
+	root["groupcaps"] = std::move(groupcaps_object);
 
 	Json::Value damage_groups_object;
-	DamageGroup::const_iterator dgiter;
-	for (dgiter = damageGroups.begin(); dgiter != damageGroups.end(); ++dgiter) {
-		damage_groups_object[dgiter->first] = dgiter->second;
+	for (const auto &damagegroup : damageGroups) {
+		damage_groups_object[damagegroup.first] = damagegroup.second;
 	}
-	root["damage_groups"] = damage_groups_object;
+	root["damage_groups"] = std::move(damage_groups_object);
 
 	fastWriteJson(root, os);
 }

src/unittest/test_filepath.cpp

@@ -238,7 +238,7 @@ void TestFilePath::testRemoveLastPathComponentWithTrailingDelimiter()
 
 void TestFilePath::testRemoveRelativePathComponent()
 {
-	std::string path, result, removed;
+	std::string path, result;
 
 	path = p("/home/user/minetest/bin");
 	result = fs::RemoveRelativePathComponents(path);

src/unittest/test_modmetadatadatabase.cpp

@@ -206,7 +206,6 @@ void TestModMetadataDatabase::testRecallFail()
 void TestModMetadataDatabase::testCreate()
 {
 	ModMetadataDatabase *mod_meta_db = mod_meta_provider->getModMetadataDatabase();
-	StringMap recalled;
 	UASSERT(mod_meta_db->setModEntry("mod1", "key1", "value1"));
 }
 
@@ -222,7 +221,6 @@ void TestModMetadataDatabase::testRecall()
 void TestModMetadataDatabase::testChange()
 {
 	ModMetadataDatabase *mod_meta_db = mod_meta_provider->getModMetadataDatabase();
-	StringMap recalled;
 	UASSERT(mod_meta_db->setModEntry("mod1", "key1", "value2"));
 }
 

src/util/quicktune_shortcutter.h

@@ -36,7 +36,7 @@ public:
 	std::string getMessage()
 	{
 		std::string s = m_message;
-		m_message = "";
+		m_message.clear();
 		if (!s.empty())
 			return std::string("[quicktune] ") + s;
 		return "";

src/util/string.h

@@ -610,7 +610,7 @@ std::vector<std::basic_string<T> > split(const std::basic_string<T> &s, T delim)
 		} else {
 			if (si == delim) {
 				tokens.push_back(current);
-				current = std::basic_string<T>();
+				current.clear();
 				last_was_escape = false;
 			} else if (si == '\\') {
 				last_was_escape = true;