(svn r11024) -Fix [FS#1173]: give a more correct error when building some things on tile 0; "Can't build on water" or "Too close to the edge" instead of "Vehicle in the way". Patch by SmatZ.

src/clear_cmd.cpp

@@ -403,8 +403,6 @@ CommandCost CmdPurchaseLandArea(TileIndex tile, uint32 flags, uint32 p1, uint32
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
-	if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 	if (IsOwnedLandTile(tile) && IsTileOwner(tile, _current_player)) {
 		return_cmd_error(STR_5807_YOU_ALREADY_OWN_IT);
 	}

src/tree_cmd.cpp

@@ -255,6 +255,11 @@ CommandCost CmdPlantTree(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 					cost.AddCost(_price.build_trees * 2);
 					break;
 
+				case MP_WATER:
+					msg = STR_3807_CAN_T_BUILD_ON_WATER;
+					continue;
+					break;
+
 				case MP_CLEAR:
 					if (!IsTileOwner(tile, OWNER_NONE) ||
 							IsBridgeAbove(tile)) {

src/water_cmd.cpp

@@ -67,12 +67,9 @@ CommandCost CmdBuildShipDepot(TileIndex tile, uint32 flags, uint32 p1, uint32 p2
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
-	if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 	Axis axis = Extract<Axis, 0>(p1);
 
 	tile2 = tile + (axis == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));
-	if (!EnsureNoVehicle(tile2)) return CMD_ERROR;
 
 	if (!IsClearWaterTile(tile) || !IsClearWaterTile(tile2))
 		return_cmd_error(STR_3801_MUST_BE_BUILT_ON_WATER);
@@ -289,15 +286,15 @@ static CommandCost ClearTile_Water(TileIndex tile, byte flags)
 		case WATER_TILE_CLEAR:
 			if (flags & DC_NO_WATER) return_cmd_error(STR_3807_CAN_T_BUILD_ON_WATER);
 
-			/* Make sure no vehicle is on the tile */
-			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 			/* Make sure it's not an edge tile. */
 			if (!IS_INT_INSIDE(TileX(tile), 1, MapMaxX() - 1) ||
 					!IS_INT_INSIDE(TileY(tile), 1, MapMaxY() - 1)) {
 				return_cmd_error(STR_0002_TOO_CLOSE_TO_EDGE_OF_MAP);
 			}
 
+			/* Make sure no vehicle is on the tile */
+			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
+
 			if (GetTileOwner(tile) != OWNER_WATER && GetTileOwner(tile) != OWNER_NONE && !CheckTileOwnership(tile)) return CMD_ERROR;
 
 			if (flags & DC_EXEC) DoClearSquare(tile);
@@ -309,12 +306,6 @@ static CommandCost ClearTile_Water(TileIndex tile, byte flags)
 			/* Make sure no vehicle is on the tile */
 			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
 
-			/* Make sure it's not an edge tile. */
-			if (!IS_INT_INSIDE(TileX(tile), 1, MapMaxX() - 1) ||
-					!IS_INT_INSIDE(TileY(tile), 1, MapMaxY() - 1)) {
-				return_cmd_error(STR_0002_TOO_CLOSE_TO_EDGE_OF_MAP);
-			}
-
 			if (flags & DC_EXEC) DoClearSquare(tile);
 			if (slope == SLOPE_N || slope == SLOPE_E || slope == SLOPE_S || slope == SLOPE_W) {
 				return CommandCost(_price.clear_water);