Merge branch 'pr-270' into jgrpp

# Conflicts:
#	src/lang/english.txt
#	src/settings_type.h
#	src/table/settings.ini

src/lang/english.txt

@@ -1470,6 +1470,12 @@ STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE_OFF              :Off
 STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE_SIMPLE           :Simple
 STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE_DETAILED         :Detailed
 
+STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE                        :Ask before demolishing structures: {STRING2}
+STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_HELPTEXT               :Ask for confirmation before irreversibly demolishing structures.
+STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_OFF                    :Off
+STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_INDUSTRY               :Industries
+STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_ALL                    :Industries and rail stations
+
 STR_CONFIG_SETTING_ADV_SIG_BRIDGE_TUN_MODES                     :Enable signals on bridges/tunnels advanced modes: {STRING2}
 STR_CONFIG_SETTING_ADV_SIG_BRIDGE_TUN_MODES_HELPTEXT            :Enables use of advanced modes of signal simulation on bridges and tunnels. When disabled, bridges/tunnels which are not already in an advanced mode cannot be changed to an advanced mode, however other players may choose to enable this setting and use an advanced mode.
 
@@ -5571,6 +5577,10 @@ STR_ERROR_NAME_MUST_BE_UNIQUE                                   :{WHITE}Name mus
 STR_ERROR_GENERIC_OBJECT_IN_THE_WAY                             :{WHITE}{1:STRING} in the way
 STR_ERROR_NOT_ALLOWED_WHILE_PAUSED                              :{WHITE}Not allowed while paused
 
+# Clear area query
+STR_QUERY_CLEAR_AREA_CAPTION                                    :{WHITE}Clear area
+STR_CLEAR_AREA_CONFIRMATION_TEXT                                :{YELLOW}You are about to destroy an important structure. Are you sure?
+
 # Local authority errors
 STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS                 :{WHITE}{TOWN} local authority refuses to allow this
 STR_ERROR_LOCAL_AUTHORITY_REFUSES_AIRPORT                       :{WHITE}{TOWN} local authority refuses to allow another airport to be built in this town

src/settings_gui.cpp

@@ -1757,6 +1757,7 @@ static SettingsContainer &GetSettingsTree()
 				construction->Add(new SettingEntry("gui.quick_goto"));
 				construction->Add(new SettingEntry("gui.default_rail_type"));
 				construction->Add(new SettingEntry("gui.default_road_type"));
+				construction->Add(new SettingEntry("gui.demolish_confirm_mode"));
 			}
 
 			SettingsPage *departureboards = interface->Add(new SettingsPage(STR_CONFIG_SETTING_INTERFACE_DEPARTUREBOARDS));

src/settings_type.h

@@ -221,6 +221,7 @@ struct GUISettings : public TimeSettings {
 	uint8  vehicle_names;                    ///< Vehicle naming scheme
 	bool   shade_trees_on_slopes;            ///< Shade trees on slopes
 	uint8  station_rating_tooltip_mode;      ///< Station rating tooltip mode
+	uint8  demolish_confirm_mode;            ///< Demolition confirmation mode
 
 	uint16 console_backlog_timeout;          ///< the minimum amount of time items should be in the console backlog before they will be removed in ~3 seconds granularity.
 	uint16 console_backlog_length;           ///< the minimum amount of items in the console backlog before items will be removed.

src/table/settings.ini

@@ -5479,6 +5479,18 @@ max      = 2
 str      = STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE
 strhelp  = STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE_HELPTEXT
 strval   = STR_CONFIG_SETTING_STATION_RATING_TOOLTIP_MODE_OFF
+
+[SDTC_VAR]
+var      = gui.demolish_confirm_mode
+type     = SLE_UINT8
+flags    = SLF_NOT_IN_SAVE | SLF_NO_NETWORK_SYNC
+guiflags = SGF_MULTISTRING
+def      = 2
+min      = 0
+max      = 2
+str      = STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE
+strhelp  = STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_HELPTEXT
+strval   = STR_CONFIG_SETTING_DEMOLISH_CONFIRM_MODE_OFF
 cat      = SC_BASIC
 
 ; For the dedicated build we'll enable dates in logs by default.

src/terraform_gui.cpp

@@ -30,6 +30,7 @@
 #include "hotkeys.h"
 #include "engine_base.h"
 #include "terraform_gui.h"
+#include "cheat_func.h"
 #include "town_gui.h"
 #include "zoom_func.h"
 
@@ -39,6 +40,12 @@
 
 #include "safeguards.h"
 
+enum DemolishConfirmMode {
+	DCM_OFF,
+	DCM_INDUSTRY,
+	DCM_INDUSTRY_RAIL_STATION,
+};
+
 void CcTerraform(const CommandCost &result, TileIndex tile, uint32 p1, uint32 p2, uint64 p3, uint32 cmd)
 {
 	if (result.Succeeded()) {
@@ -95,6 +102,40 @@ static void GenerateRockyArea(TileIndex end, TileIndex start)
 	if (success && _settings_client.sound.confirm) SndPlayTileFx(SND_1F_CONSTRUCTION_OTHER, end);
 }
 
+/** Checks if the area contains any structures that are important enough to query about first */
+static bool IsQueryConfirmIndustryOrRailStationInArea(TileIndex start_tile, TileIndex end_tile, bool diagonal)
+{
+	if (_settings_client.gui.demolish_confirm_mode == DCM_OFF) return false;
+
+	std::unique_ptr<TileIterator> tile_iterator;
+
+	if (diagonal) {
+		tile_iterator = std::make_unique<DiagonalTileIterator>(end_tile, start_tile);
+	} else {
+		tile_iterator = std::make_unique<OrthogonalTileIterator>(end_tile, start_tile);
+	}
+
+	bool destroying_industry_or_station = false;
+
+	for (; *tile_iterator != INVALID_TILE; ++(*tile_iterator)) {
+		if ((_cheats.magic_bulldozer.value && IsTileType(*tile_iterator, MP_INDUSTRY)) ||
+				(_settings_client.gui.demolish_confirm_mode == DCM_INDUSTRY_RAIL_STATION && IsRailStationTile(*tile_iterator))) {
+			destroying_industry_or_station = true;
+			break;
+		}
+	}
+
+	return destroying_industry_or_station;
+}
+
+static CommandContainer _demolish_area_command;
+
+static void DemolishAreaConfirmationCallback(Window*, bool confirmed) {
+	if (confirmed) {
+		DoCommandP(&_demolish_area_command);
+	}
+}
+
 /**
  * A central place to handle all X_AND_Y dragged GUI functions.
  * @param proc       Procedure related to the dragging
@@ -114,9 +155,16 @@ bool GUIPlaceProcDragXY(ViewportDragDropSelectionProcess proc, TileIndex start_t
 	}
 
 	switch (proc) {
-		case DDSP_DEMOLISH_AREA:
+		case DDSP_DEMOLISH_AREA: {
-			DoCommandP(end_tile, start_tile, _ctrl_pressed ? 1 : 0, CMD_CLEAR_AREA | CMD_MSG(STR_ERROR_CAN_T_CLEAR_THIS_AREA), CcPlaySound_EXPLOSION);
+			_demolish_area_command = NewCommandContainerBasic(end_tile, start_tile, _ctrl_pressed ? 1 : 0, CMD_CLEAR_AREA | CMD_MSG(STR_ERROR_CAN_T_CLEAR_THIS_AREA), CcPlaySound_EXPLOSION);
+
+			if (IsQueryConfirmIndustryOrRailStationInArea(start_tile, end_tile, _ctrl_pressed)) {
+				ShowQuery(STR_QUERY_CLEAR_AREA_CAPTION, STR_CLEAR_AREA_CONFIRMATION_TEXT, nullptr, DemolishAreaConfirmationCallback);
+			} else {
+				DemolishAreaConfirmationCallback(nullptr, true);
+			}
 			break;
+		}
 		case DDSP_RAISE_AND_LEVEL_AREA:
 			DoCommandP(end_tile, start_tile, LM_RAISE << 1 | (_ctrl_pressed ? 1 : 0), CMD_LEVEL_LAND | CMD_MSG(STR_ERROR_CAN_T_RAISE_LAND_HERE), CcTerraform);
 			break;