Merge branch 'master' into jgrpp

# Conflicts:
#	regression/regression/result.txt
#	src/aircraft_cmd.cpp
#	src/airport_gui.cpp
#	src/articulated_vehicles.cpp
#	src/console_cmds.cpp
#	src/date_gui.cpp
#	src/engine.cpp
#	src/genworld_gui.cpp
#	src/gfx_layout_fallback.cpp
#	src/group_gui.cpp
#	src/hotkeys.cpp
#	src/network/core/tcp_connect.cpp
#	src/network/core/tcp_listen.h
#	src/newgrf.cpp
#	src/newgrf.h
#	src/newgrf_engine.cpp
#	src/newgrf_gui.cpp
#	src/newgrf_station.cpp
#	src/openttd.cpp
#	src/order_gui.cpp
#	src/os/macosx/osx_main.cpp
#	src/pathfinder/yapf/yapf_node_rail.hpp
#	src/rail_gui.cpp
#	src/saveload/afterload.cpp
#	src/saveload/cargopacket_sl.cpp
#	src/saveload/linkgraph_sl.cpp
#	src/saveload/station_sl.cpp
#	src/script/api/script_industrytype.cpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/settings_table.cpp
#	src/settingsgen/settingsgen.cpp
#	src/station.cpp
#	src/station_cmd.cpp
#	src/strings.cpp
#	src/timer/timer_game_calendar.cpp
#	src/timer/timer_game_calendar.h
#	src/timer/timer_manager.h
#	src/timer/timer_window.cpp
#	src/timetable_cmd.cpp
#	src/toolbar_gui.cpp
#	src/town_cmd.cpp
#	src/town_gui.cpp
#	src/train_gui.cpp
#	src/vehicle_cmd.h
#	src/vehicle_gui.cpp
#	src/viewport.cpp
#	src/widgets/dropdown.cpp
#	src/window_func.h
#	src/window_gui.h

src/widgets/dropdown.cpp

@@ -137,7 +137,7 @@ struct DropdownWindow : Window {
 	DropdownWindow(Window *parent, DropDownList &&list, int selected, int button, bool instant_close, const Point &position, const Dimension &size, Colours wi_colour, bool scroll, DropDownSyncFocus sync_parent_focus)
 			: Window(&_dropdown_desc), list(std::move(list))
 	{
-		assert(this->list.size() > 0);
+		assert(!this->list.empty());
 
 		this->position = position;
 		this->parent_wnd_class = parent->window_class;
@@ -179,7 +179,7 @@ struct DropdownWindow : Window {
 		this->scrolling_timer  = GUITimer(MILLISECONDS_PER_TICK);
 	}
 
-	void Close() override
+	void Close([[maybe_unused]] int data = 0) override
 	{
 		/* Make the dropdown "invisible", so it doesn't affect new window placement.
 		 * Also mark it dirty in case the callback deals with the screen. (e.g. screenshots). */
@@ -493,7 +493,7 @@ void ShowDropDownMenu(Window *w, const StringID *strings, int selected, int butt
 
 	for (uint i = 0; strings[i] != INVALID_STRING_ID; i++) {
 		if (i >= 32 || !HasBit(hidden_mask, i)) {
-			list.emplace_back(new DropDownListStringItem(strings[i], i, i < 32 && HasBit(disabled_mask, i)));
+			list.push_back(std::make_unique<DropDownListStringItem>(strings[i], i, i < 32 && HasBit(disabled_mask, i)));
 		}
 	}
 

src/widgets/slider.cpp

@@ -29,7 +29,7 @@ static const int SLIDER_WIDTH = 3;
 void DrawSliderWidget(Rect r, int min_value, int max_value, int value, const std::map<int, StringID> &labels)
 {
 	/* Allow space for labels. We assume they are in the small font. */
-	if (labels.size() > 0) r.bottom -= FONT_HEIGHT_SMALL + WidgetDimensions::scaled.hsep_normal;
+	if (!labels.empty()) r.bottom -= FONT_HEIGHT_SMALL + WidgetDimensions::scaled.hsep_normal;
 
 	max_value -= min_value;