Paper/patches/server/0273-force-entity-dismount-during-teleportation.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Thu, 15 Nov 2018 13:38:37 +0000
Subject: [PATCH] force entity dismount during teleportation

Entities must be dismounted before teleportation in order to avoid
multiple issues in the server with regards to teleportation, shamefully,
too many plugins rely on the events firing, which means that not firing
these events caues more issues than it solves;

In order to counteract this, Entity dismount/exit vehicle events have
been modified to supress cancellation (and has a method to allow plugins
to check if this has been set), noting that cancellation will be silently
surpressed given that plugins are not expecting this event to not be cancellable.

This is a far from ideal scenario, however: given the current state of this
event and other alternatives causing issues elsewhere, I believe that
this is going to be the best soultion all around.

Improvements/suggestions welcome!

diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index d39aec1b3233e91aa5b953396d876e7466a9a5bc..28708e1e8ade8fbfec24120478d250ddf1351bf4 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2601,11 +2601,16 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
     }
 
     public void removeVehicle() {
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    public void stopRiding(boolean suppressCancellation) {
+        // Paper end - Force entity dismount during teleportation
         if (this.vehicle != null) {
             Entity entity = this.vehicle;
 
             this.vehicle = null;
-            if (!entity.removePassenger(this)) this.vehicle = entity; // CraftBukkit
+            if (!entity.removePassenger(this, suppressCancellation)) this.vehicle = entity; // CraftBukkit // Paper - Force entity dismount during teleportation
         }
 
     }
@@ -2636,7 +2641,10 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
         }
     }
 
-    protected boolean removePassenger(Entity entity) { // CraftBukkit
+    // Paper start - Force entity dismount during teleportation
+    protected boolean removePassenger(Entity entity) { return removePassenger(entity, false);}
+    protected boolean removePassenger(Entity entity, boolean suppressCancellation) { // CraftBukkit
+        // Paper end - Force entity dismount during teleportation
         if (entity.getVehicle() == this) {
             throw new IllegalStateException("Use x.stopRiding(y), not y.removePassenger(x)");
         } else {
@@ -2646,7 +2654,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
             if (this.getBukkitEntity() instanceof Vehicle && entity.getBukkitEntity() instanceof LivingEntity) {
                 VehicleExitEvent event = new VehicleExitEvent(
                         (Vehicle) this.getBukkitEntity(),
-                        (LivingEntity) entity.getBukkitEntity()
+                        (LivingEntity) entity.getBukkitEntity(), !suppressCancellation // Paper - Force entity dismount during teleportation
                 );
                 // Suppress during worldgen
                 if (this.valid) {
@@ -2659,7 +2667,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
                 }
             }
 
-            EntityDismountEvent event = new EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity());
+            EntityDismountEvent event = new EntityDismountEvent(entity.getBukkitEntity(), this.getBukkitEntity(), !suppressCancellation); // Paper - Force entity dismount during teleportation
             // Suppress during worldgen
             if (this.valid) {
                 Bukkit.getPluginManager().callEvent(event);
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index bac78415e34d41e3a5de482b86185f2202ecf068..a4eee658ecfc0f25e854c17a7715cb16715859b1 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3585,9 +3585,15 @@ public abstract class LivingEntity extends Entity implements Attackable {
 
     @Override
     public void stopRiding() {
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    @Override
+    public void stopRiding(boolean suppressCancellation) {
+        // Paper end - Force entity dismount during teleportation
         Entity entity = this.getVehicle();
 
-        super.stopRiding();
+        super.stopRiding(suppressCancellation); // Paper - Force entity dismount during teleportation
         if (entity != null && entity != this.getVehicle() && !this.level().isClientSide) {
             this.dismountVehicle(entity);
         }
diff --git a/src/main/java/net/minecraft/world/entity/player/Player.java b/src/main/java/net/minecraft/world/entity/player/Player.java
index b27a6719edd47f7ecb3f8c5560a36fc201efea36..bbafbeff99a7c1bd2d9e27982671a017071f829c 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -1150,7 +1150,13 @@ public abstract class Player extends LivingEntity {
 
     @Override
     public void removeVehicle() {
-        super.removeVehicle();
+        // Paper start - Force entity dismount during teleportation
+        stopRiding(false);
+    }
+    @Override
+    public void stopRiding(boolean suppressCancellation) {
+        super.stopRiding(suppressCancellation);
+        // Paper end - Force entity dismount during teleportation
         this.boardingCooldown = 0;
     }