(svn r13974) -Fix [YAPP]: A train crash could lead to stale reservations. (michi_cc)

1 files changed, 10 insertions, 1 deletions

diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index efdbd5c2a..dc7ff694c 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -3059,7 +3059,8 @@ bool TryPathReserve(Vehicle *v, bool mark_as_stuck, bool first_tile_okay)
 		}
 	}
 
-	PBSTileInfo origin = FollowTrainReservation(v);
+	Vehicle *other_train = NULL;
+	PBSTileInfo origin = FollowTrainReservation(v, &other_train);
 	/* If we have a reserved path and the path ends at a safe tile, we are finished already. */
 	if (origin.okay && (v->tile != origin.tile || first_tile_okay)) {
 		/* Can't be stuck then. */
@@ -3067,6 +3068,14 @@ bool TryPathReserve(Vehicle *v, bool mark_as_stuck, bool first_tile_okay)
 		ClrBit(v->u.rail.flags, VRF_TRAIN_STUCK);
 		return true;
 	}
+	/* The path we are driving on is alread blocked by some other train.
+	 * This can only happen when tracks and signals are changed. A crash
+	 * is probably imminent, don't do any further reservation because
+	 * it might cause stale reservations. */
+	if (other_train != NULL && v->tile != origin.tile) {
+		if (mark_as_stuck) MarkTrainAsStuck(v);
+		return false;
+	}
 
 	/* If we are in a depot, tentativly reserve the depot. */
 	if (v->u.rail.track & TRACK_BIT_DEPOT) {