Feature: option to auto remove signals when in the way during rail construction (#8274)

1 files changed, 20 insertions, 6 deletions

diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index 34ad07d52..8af7871fc 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -262,10 +262,6 @@ static CommandCost CheckTrackCombination(TileIndex tile, TrackBits to_build, uin
 		return_cmd_error(STR_ERROR_ALREADY_BUILT);
 	}
 
-	/* Let's see if we may build this */
-	if (HasSignals(tile) && future != TRACK_BIT_HORZ && future != TRACK_BIT_VERT) {
-		return_cmd_error(STR_ERROR_MUST_REMOVE_SIGNALS_FIRST);
-	}
 	/* Normally, we may overlap and any combination is valid */
 	return CommandCost();
 }
@@ -432,7 +428,9 @@ static inline bool ValParamTrackOrientation(Track track)
  * @param tile tile  to build on
  * @param flags operation to perform
  * @param p1 railtype of being built piece (normal, mono, maglev)
- * @param p2 rail track to build
+ * @param p2 various bitstuffed elements
+ *           - (bit  0- 2) - track-orientation, valid values: 0-5 (@see Track)
+ *           - (bit  3)    - 0 = error on signal in the way, 1 = auto remove signals when in the way
  * @param text unused
  * @return the cost of this operation or an error
  */
@@ -440,6 +438,7 @@ CommandCost CmdBuildSingleRail(TileIndex tile, DoCommandFlag flags, uint32 p1, u
 {
 	RailType railtype = Extract<RailType, 0, 6>(p1);
 	Track track = Extract<Track, 0, 3>(p2);
+	bool auto_remove_signals = HasBit(p2, 3);
 	CommandCost cost(EXPENSES_CONSTRUCTION);
 
 	if (!ValParamRailtype(railtype) || !ValParamTrackOrientation(track)) return CMD_ERROR;
@@ -460,6 +459,19 @@ CommandCost CmdBuildSingleRail(TileIndex tile, DoCommandFlag flags, uint32 p1, u
 			if (ret.Succeeded()) ret = EnsureNoTrainOnTrack(tile, track);
 			if (ret.Failed()) return ret;
 
+			if (HasSignals(tile) && TracksOverlap(GetTrackBits(tile) | TrackToTrackBits(track))) {
+				/* If adding the new track causes any overlap, all signals must be removed first */
+				if (!auto_remove_signals) return_cmd_error(STR_ERROR_MUST_REMOVE_SIGNALS_FIRST);
+
+				for (Track track_it = TRACK_BEGIN; track_it < TRACK_END; track_it++) {
+					if (HasTrack(tile, track_it) && HasSignalOnTrack(tile, track_it)) {
+						CommandCost ret_remove_signals = DoCommand(tile, track_it, 0, flags, CMD_REMOVE_SIGNALS);
+						if (ret_remove_signals.Failed()) return ret_remove_signals;
+						cost.AddCost(ret_remove_signals);
+					}
+				}
+			}
+
 			ret = CheckRailSlope(tileh, trackbit, GetTrackBits(tile), tile);
 			if (ret.Failed()) return ret;
 			cost.AddCost(ret);
@@ -868,6 +880,7 @@ static CommandCost ValidateAutoDrag(Trackdir *trackdir, TileIndex start, TileInd
  * - p2 = (bit 6-8) - track-orientation, valid values: 0-5 (Track enum)
  * - p2 = (bit 9)   - 0 = build, 1 = remove tracks
  * - p2 = (bit 10)  - 0 = build up to an obstacle, 1 = fail if an obstacle is found (used for AIs).
+ * - p2 = (bit 11)  - 0 = error on signal in the way, 1 = auto remove signals when in the way
  * @param text unused
  * @return the cost of this operation or an error
  */
@@ -876,6 +889,7 @@ static CommandCost CmdRailTrackHelper(TileIndex tile, DoCommandFlag flags, uint3
 	CommandCost total_cost(EXPENSES_CONSTRUCTION);
 	Track track = Extract<Track, 6, 3>(p2);
 	bool remove = HasBit(p2, 9);
+	bool auto_remove_signals = HasBit(p2, 11);
 	RailType railtype = Extract<RailType, 0, 6>(p2);
 
 	if ((!remove && !ValParamRailtype(railtype)) || !ValParamTrackOrientation(track)) return CMD_ERROR;
@@ -889,7 +903,7 @@ static CommandCost CmdRailTrackHelper(TileIndex tile, DoCommandFlag flags, uint3
 	bool had_success = false;
 	CommandCost last_error = CMD_ERROR;
 	for (;;) {
-		CommandCost ret = DoCommand(tile, remove ? 0 : railtype, TrackdirToTrack(trackdir), flags, remove ? CMD_REMOVE_SINGLE_RAIL : CMD_BUILD_SINGLE_RAIL);
+		CommandCost ret = DoCommand(tile, remove ? 0 : railtype, TrackdirToTrack(trackdir) | (auto_remove_signals << 3), flags, remove ? CMD_REMOVE_SINGLE_RAIL : CMD_BUILD_SINGLE_RAIL);
 
 		if (ret.Failed()) {
 			last_error = ret;