Paper/patches/unapplied/server/0284-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 c46ad2013439f043145fb7fc67bbcd80728e3c16..f746829f1e94ee58821e56ec4192269add00395b 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2570,11 +2570,16 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
     }
 
     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
         }
 
     }
@@ -2605,7 +2610,10 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
         }
     }
 
-    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 {
@@ -2615,7 +2623,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
             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) {
@@ -2628,7 +2636,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
                 }
             }
 
-            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 1a328de32b69b69814e11a5b6bc55bfccf408d6b..4be7b136dd2b35b0637a1455985ab99bbd3af0a5 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3492,9 +3492,15 @@ 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 83c7ba56900ce40f71d98062bf15110a76597dce..3c3c953f05c18279d3245fe6bc8afef83cd62cd1 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -1141,7 +1141,13 @@ 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;
     }