Paper/patches/server/0912-Restore-vanilla-entity-drops-behavior.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Tue, 22 Mar 2022 09:34:41 -0700
Subject: [PATCH] Restore vanilla entity drops behavior

Instead of just tracking the itemstacks, this tracks with it, the
action to take with that itemstack to apply the correct logic
on dropping the item instead of generalizing it for all dropped
items like CB does.

diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index b65d816bb9feb18ecf74e10e9728c302e5657587..62ec627e80b87a92a2a51ba9fc3626a67636855f 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -976,20 +976,20 @@ public class ServerPlayer extends net.minecraft.world.entity.player.Player {
         if (this.isRemoved()) {
             return;
         }
-        java.util.List<org.bukkit.inventory.ItemStack> loot = new java.util.ArrayList<>(this.getInventory().getContainerSize());
+        List<DefaultDrop> loot = new java.util.ArrayList<>(this.getInventory().getContainerSize()); // Paper - Restore vanilla drops behavior
         boolean keepInventory = this.level().getGameRules().getBoolean(GameRules.RULE_KEEPINVENTORY) || this.isSpectator();
 
         if (!keepInventory) {
             for (ItemStack item : this.getInventory().getContents()) {
                 if (!item.isEmpty() && !EnchantmentHelper.has(item, EnchantmentEffectComponents.PREVENT_EQUIPMENT_DROP)) {
-                    loot.add(CraftItemStack.asCraftMirror(item).markForInventoryDrop());
+                    loot.add(new DefaultDrop(item, stack -> this.drop(stack, true, false, false))); // Paper - Restore vanilla drops behavior; drop function taken from Inventory#dropAll (don't fire drop event)
                 }
             }
         }
         if (this.shouldDropLoot() && this.level().getGameRules().getBoolean(GameRules.RULE_DOMOBLOOT)) { // Paper - fix player loottables running when mob loot gamerule is false
         // SPIGOT-5071: manually add player loot tables (SPIGOT-5195 - ignores keepInventory rule)
         this.dropFromLootTable(damageSource, this.lastHurtByPlayerTime > 0);
-        this.dropCustomDeathLoot(this.serverLevel(), damageSource, flag);
+        // Paper - Restore vanilla drops behaviour; custom death loot is a noop on server player, remove.
 
         loot.addAll(this.drops);
         this.drops.clear(); // SPIGOT-5188: make sure to clear
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index f163cb3c75e90b96b3794a7e0c5b803268814c8c..e88c88b6f87dddda8e8e3ed215a8f2c166afa3ef 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2562,6 +2562,25 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
 
     @Nullable
     public ItemEntity spawnAtLocation(ItemStack stack, float yOffset) {
+        // Paper start - Restore vanilla drops behavior
+        return this.spawnAtLocation(stack, yOffset, null);
+    }
+    public record DefaultDrop(Item item, org.bukkit.inventory.ItemStack stack, @Nullable java.util.function.Consumer<ItemStack> dropConsumer) {
+        public DefaultDrop(final ItemStack stack, final java.util.function.Consumer<ItemStack> dropConsumer) {
+            this(stack.getItem(), org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(stack), dropConsumer);
+        }
+
+        public void runConsumer(final java.util.function.Consumer<org.bukkit.inventory.ItemStack> fallback) {
+            if (this.dropConsumer == null || org.bukkit.craftbukkit.inventory.CraftItemType.bukkitToMinecraft(this.stack.getType()) != this.item) {
+                fallback.accept(this.stack);
+            } else {
+                this.dropConsumer.accept(org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(this.stack));
+            }
+        }
+    }
+    @Nullable
+    public ItemEntity spawnAtLocation(ItemStack stack, float yOffset, @Nullable java.util.function.Consumer<? super ItemEntity> delayedAddConsumer) {
+        // Paper end - Restore vanilla drops behavior
         if (stack.isEmpty()) {
             return null;
         } else if (this.level().isClientSide) {
@@ -2569,14 +2588,21 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
         } else {
             // CraftBukkit start - Capture drops for death event
             if (this instanceof net.minecraft.world.entity.LivingEntity && !((net.minecraft.world.entity.LivingEntity) this).forceDrops) {
-                ((net.minecraft.world.entity.LivingEntity) this).drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(stack)); // Paper - mirror so we can destroy it later
+                // Paper start - Restore vanilla drops behavior
+                ((net.minecraft.world.entity.LivingEntity) this).drops.add(new net.minecraft.world.entity.Entity.DefaultDrop(stack, itemStack -> {
+                    ItemEntity itemEntity = new ItemEntity(this.level, this.getX(), this.getY() + (double) yOffset, this.getZ(), itemStack); // stack is copied before consumer
+                    itemEntity.setDefaultPickUpDelay();
+                    this.level.addFreshEntity(itemEntity);
+                    if (delayedAddConsumer != null) delayedAddConsumer.accept(itemEntity);
+                }));
+                // Paper end - Restore vanilla drops behavior
                 return null;
             }
             // CraftBukkit end
             ItemEntity entityitem = new ItemEntity(this.level(), this.getX(), this.getY() + (double) yOffset, this.getZ(), stack.copy()); // Paper - copy so we can destroy original
             stack.setCount(0); // Paper - destroy this item - if this ever leaks due to game bugs, ensure it doesn't dupe
 
-            entityitem.setDefaultPickUpDelay();
+            entityitem.setDefaultPickUpDelay(); // Paper - diff on change (in dropConsumer)
             // Paper start - Call EntityDropItemEvent
             return this.spawnAtLocation(entityitem);
         }
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 0c67f04ae7eeaa10a90419031447ad5397c6b9e2..6b2dc430126713e11658f94762035ff10bbe018c 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -278,7 +278,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
     protected float appliedScale;
     // CraftBukkit start
     public int expToDrop;
-    public ArrayList<org.bukkit.inventory.ItemStack> drops = new ArrayList<org.bukkit.inventory.ItemStack>();
+    public ArrayList<DefaultDrop> drops = new ArrayList<>(); // Paper - Restore vanilla drops behavior
     public final org.bukkit.craftbukkit.attribute.CraftAttributeMap craftAttributes;
     public boolean collides = true;
     public Set<UUID> collidableExemptions = new HashSet<>();
diff --git a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
index 1b49090a466bc74d9e5f2815314955b6dfbb83dc..62271e74399a827a488159da234465ef18e15e6e 100644
--- a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
+++ b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
@@ -538,10 +538,9 @@ public class WitherBoss extends Monster implements PowerableMob, RangedAttackMob
     @Override
     protected void dropCustomDeathLoot(ServerLevel world, DamageSource source, boolean causedByPlayer) {
         super.dropCustomDeathLoot(world, source, causedByPlayer);
-        ItemEntity entityitem = this.spawnAtLocation((ItemLike) Items.NETHER_STAR);
-
+        ItemEntity entityitem = this.spawnAtLocation(new net.minecraft.world.item.ItemStack(Items.NETHER_STAR), 0, ItemEntity::setExtendedLifetime); // Paper - Restore vanilla drops behavior; spawnAtLocation returns null so modify the item entity with a consumer
         if (entityitem != null) {
-            entityitem.setExtendedLifetime();
+            entityitem.setExtendedLifetime(); // Paper - diff on change
         }
 
     }
diff --git a/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java b/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
index 5bcb9a53ebebeef4bd6ec2458df4b63002ebd804..2f398750bfee5758ad8b1367b6fc14364e4de776 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
@@ -621,7 +621,7 @@ public class ArmorStand extends LivingEntity {
         ItemStack itemstack = new ItemStack(Items.ARMOR_STAND);
 
         itemstack.set(DataComponents.CUSTOM_NAME, this.getCustomName());
-        this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asBukkitCopy(itemstack)); // CraftBukkit - add to drops
+        this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior
         return this.brokenByAnything(world, damageSource); // Paper
     }
 
@@ -635,7 +635,7 @@ public class ArmorStand extends LivingEntity {
         for (i = 0; i < this.handItems.size(); ++i) {
             itemstack = (ItemStack) this.handItems.get(i);
             if (!itemstack.isEmpty()) {
-                this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(itemstack)); // CraftBukkit - add to drops // Paper - mirror so we can destroy it later - though this call site was safe
+                this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition().above(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior; mirror so we can destroy it later - though this call site was safe & spawn drops correctly
                 this.handItems.set(i, ItemStack.EMPTY);
             }
         }
@@ -643,7 +643,7 @@ public class ArmorStand extends LivingEntity {
         for (i = 0; i < this.armorItems.size(); ++i) {
             itemstack = (ItemStack) this.armorItems.get(i);
             if (!itemstack.isEmpty()) {
-                this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(itemstack)); // CraftBukkit - add to drops // Paper - mirror so we can destroy it later - though this call site was safe
+                this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition().above(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior; mirror so we can destroy it later - though this call site was safe & spawn drops correctly
                 this.armorItems.set(i, ItemStack.EMPTY);
             }
         }
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index 2690c471b819f8308f6db44150025dfa323d4e0c..0d6cdb6b0dfd84f619a5e43150165b4606a96bcd 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -975,18 +975,24 @@ public class CraftEventFactory {
     }
 
     public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource) {
-        return CraftEventFactory.callEntityDeathEvent(victim, damageSource, new ArrayList<org.bukkit.inventory.ItemStack>(0));
+        return CraftEventFactory.callEntityDeathEvent(victim, damageSource, new ArrayList<>(0)); // Paper - Restore vanilla drops behavior
     }
 
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops) {
+    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<Entity.DefaultDrop> drops) { // Paper - Restore vanilla drops behavior
         // Paper start
         return CraftEventFactory.callEntityDeathEvent(victim, damageSource, drops, com.google.common.util.concurrent.Runnables.doNothing());
     }
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops, Runnable lootCheck) {
+
+    private static final java.util.function.Function<org.bukkit.inventory.ItemStack, Entity.DefaultDrop> FROM_FUNCTION = stack -> {
+        if (stack == null) return null;
+        return new Entity.DefaultDrop(CraftItemType.bukkitToMinecraft(stack.getType()), stack, null);
+    };
+
+    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<Entity.DefaultDrop> drops, Runnable lootCheck) { // Paper
         // Paper end
         CraftLivingEntity entity = (CraftLivingEntity) victim.getBukkitEntity();
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(damageSource);
-        EntityDeathEvent event = new EntityDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(damageSource.getEntity()));
+        EntityDeathEvent event = new EntityDeathEvent(entity, bukkitDamageSource, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward(damageSource.getEntity())); // Paper - Restore vanilla drops behavior
         populateFields(victim, event); // Paper - make cancellable
         CraftWorld world = (CraftWorld) entity.getWorld();
         Bukkit.getServer().getPluginManager().callEvent(event);
@@ -1000,20 +1006,24 @@ public class CraftEventFactory {
         victim.expToDrop = event.getDroppedExp();
         lootCheck.run(); // Paper - advancement triggers before destroying items
 
-        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
+        // Paper start - Restore vanilla drops behavior
+        for (Entity.DefaultDrop drop : drops) {
+            if (drop == null) continue;
+            final org.bukkit.inventory.ItemStack stack = drop.stack();
+            // Paper end - Restore vanilla drops behavior
             if (stack == null || stack.getType() == Material.AIR || stack.getAmount() == 0) continue;
 
-            world.dropItem(entity.getLocation(), stack); // Paper - note: dropItem already clones due to this being bukkit -> NMS
+            drop.runConsumer(s -> world.dropItem(entity.getLocation(), s)); // Paper - Restore vanilla drops behavior
             if (stack instanceof CraftItemStack) stack.setAmount(0); // Paper - destroy this item - if this ever leaks due to game bugs, ensure it doesn't dupe, but don't nuke bukkit stacks of manually added items
         }
 
         return event;
     }
 
-    public static PlayerDeathEvent callPlayerDeathEvent(ServerPlayer victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure
+    public static PlayerDeathEvent callPlayerDeathEvent(ServerPlayer victim, DamageSource damageSource, List<Entity.DefaultDrop> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure & Restore vanilla drops behavior
         CraftPlayer entity = victim.getBukkitEntity();
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(damageSource);
-        PlayerDeathEvent event = new PlayerDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(damageSource.getEntity()), 0, deathMessage);
+        PlayerDeathEvent event = new PlayerDeathEvent(entity, bukkitDamageSource, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward(damageSource.getEntity()), 0, deathMessage); // Paper - Restore vanilla drops behavior
         event.setKeepInventory(keepInventory);
         event.setKeepLevel(victim.keepLevel); // SPIGOT-2222: pre-set keepLevel
         populateFields(victim, event); // Paper - make cancellable
@@ -1031,16 +1041,14 @@ public class CraftEventFactory {
         victim.expToDrop = event.getDroppedExp();
         victim.newExp = event.getNewExp();
 
-        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
+        // Paper start - Restore vanilla drops behavior
+        for (Entity.DefaultDrop drop : drops) {
+            if (drop == null) continue;
+            final org.bukkit.inventory.ItemStack stack = drop.stack();
+            // Paper end - Restore vanilla drops behavior
             if (stack == null || stack.getType() == Material.AIR) continue;
 
-            if (stack instanceof CraftItemStack craftItemStack && craftItemStack.isForInventoryDrop()) {
-                victim.drop(CraftItemStack.asNMSCopy(stack), true, false, false); // SPIGOT-7800, SPIGOT-7801: Vanilla Behaviour for Player Inventory dropped items
-            } else {
-                victim.forceDrops = true;
-                victim.spawnAtLocation(CraftItemStack.asNMSCopy(stack)); // SPIGOT-7806: Vanilla Behaviour for items not related to Player Inventory dropped items
-                victim.forceDrops = false;
-            }
+            drop.runConsumer(s -> victim.drop(CraftItemStack.unwrap(s), true, false, false)); // Paper - Restore vanilla drops behavior
         }
 
         return event;
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
index c5a09f086d35f84c0a30266f78e06e2dfb5603e6..f33742ee06e8443a5f5adaaa987d7523dc193b5a 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
@@ -130,27 +130,6 @@ public final class CraftItemStack extends ItemStack {
         this.setItemMeta(itemMeta);
     }
 
-    /**
-     * Gets if the item is marked as an inventory drop in death events.
-     *
-     * @return true if the item is marked as an inventory drop
-     */
-    @ApiStatus.Internal
-    public boolean isForInventoryDrop() {
-        return this.isForInventoryDrop;
-    }
-
-    /**
-     * Marks this item as an inventory drop in death events.
-     *
-     * @return the ItemStack marked as an inventory drop
-     */
-    @ApiStatus.Internal
-    public ItemStack markForInventoryDrop() {
-        this.isForInventoryDrop = true;
-        return this;
-    }
-
     @Override
     public MaterialData getData() {
         return this.handle != null ? CraftMagicNumbers.getMaterialData(this.handle.getItem()) : super.getData();