Add a WarnCrush method to ICrushable which is called when a crusher begins to enter the cell.

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -142,6 +142,7 @@ namespace OpenRA.Traits
     public interface ICrushable
     {
         void OnCrush(Actor crusher);
+		void WarnCrush(Actor crusher);
 		bool CrushableBy(string[] crushClasses, Player owner);
     }
 

OpenRA.Mods.RA/Buildings/Wall.cs

@@ -32,6 +32,8 @@ namespace OpenRA.Mods.RA.Buildings
 			this.info = info;
 		}
 
+		public void WarnCrush(Actor crusher) {}
+
 		public bool CrushableBy(string[] crushClasses, Player crushOwner)
 		{
 			if (crushOwner.Stances[self.Owner] == Stance.Ally)

OpenRA.Mods.RA/Crate.cs

@@ -56,6 +56,8 @@ namespace OpenRA.Mods.RA
 			this.Info = info;
 		}
 
+		public void WarnCrush(Actor crusher) {}
+
 		public void OnCrush(Actor crusher)
 		{
 			var shares = self.TraitsImplementing<CrateAction>().Select(

OpenRA.Mods.RA/Mine.cs

@@ -40,6 +40,8 @@ namespace OpenRA.Mods.RA
 			this.location = init.Get<LocationInit,int2>();
 		}
 
+		public void WarnCrush(Actor crusher) {}
+
 		public void OnCrush(Actor crusher)
 		{
 			if (crusher.HasTrait<MineImmune>() || self.Owner.Stances[crusher.Owner] == Stance.Ally)

OpenRA.Mods.RA/Move/Mobile.cs

@@ -329,6 +329,17 @@ namespace OpenRA.Mods.RA.Move
             return Info.CanEnterCell(self.World, self.Owner, cell, ignoreActor, checkTransientActors);
         }
 
+		public void EnteringCell(Actor self)
+		{
+			var crushable = self.World.ActorMap.GetUnitsAt(toCell).Where(a => a != self && a.HasTrait<ICrushable>());
+            foreach (var a in crushable)
+            {
+				var crushActions = a.TraitsImplementing<ICrushable>().Where(b => b.CrushableBy(Info.Crushes, self.Owner));
+                foreach (var b in crushActions)
+					b.WarnCrush(self);
+			}
+		}
+
         public void FinishedMoving(Actor self)
         {
             var crushable = self.World.ActorMap.GetUnitsAt(toCell).Where(a => a != self && a.HasTrait<ICrushable>());

OpenRA.Mods.RA/Move/Move.cs

@@ -349,6 +349,7 @@ namespace OpenRA.Mods.RA.Move
 					mobile.Facing,
 					moveFraction - moveFractionTotal );
 				
+				mobile.EnteringCell(self);
 				mobile.SetLocation( mobile.toCell, mobile.__toSubCell, mobile.toCell, mobile.__toSubCell );
 				return ret2;
 			}