PaperMC/Spigot-Server-Patches/0271-Don-t-call-getItemMeta-on-hasItemMeta.patch

From a9a10de78a820a47f07c2b62a31bc46ee49d0350 Mon Sep 17 00:00:00 2001
From: Hugo Manrique <hugmanrique@gmail.com>
Date: Thu, 26 Jul 2018 14:10:23 +0200
Subject: [PATCH] Don't call getItemMeta on hasItemMeta

Spigot 1.13 checks if any field (which are manually copied from the ItemStack's "tag" NBT tag) on the ItemMeta class of an ItemStack is set.

We could just check if the "tag" NBT tag is empty, albeit that would break some plugins. The only general tag added on 1.13 is "Damage", and we can just check if the "tag" NBT tag contains any other tag that's not "Damage" (https://minecraft.gamepedia.com/Player.dat_format#Item_structure) making the `hasItemStack` method behave as before.

Returns true if getDamage() == 0 or has damage tag or other tag is set.
Check the `ItemMetaTest#testTaggedButNotMeta` method to see how this method behaves.

diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
index 1609e6bbb..8a6a13537 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
@@ -536,7 +536,7 @@ public final class CraftItemStack extends ItemStack {
 
     @Override
     public boolean hasItemMeta() {
-        return hasItemMeta(handle) && !CraftItemFactory.instance().equals(getItemMeta(), null);
+        return hasItemMeta(handle) && (handle.getDamage() != 0 || (handle.getTag() != null && handle.getTag().map.size() >= (handle.getTag().hasKey(CraftMetaItem.DAMAGE.NBT) ? 2 : 1))); // Paper - keep 1.12 CraftBukkit behavior without calling getItemMeta
     }
 
     static boolean hasItemMeta(net.minecraft.server.ItemStack item) {
diff --git a/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java b/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
index 2a0852675..f30f74312 100644
--- a/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
+++ b/src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java
@@ -4,6 +4,7 @@ import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections; // Paper
 import java.util.List;
 import java.util.UUID;
 import com.destroystokyo.paper.inventory.meta.ArmorStandMeta; // Paper
@@ -180,7 +181,47 @@ public class ItemMetaTest extends AbstractTestingBase {
 
         assertThat("noTag and enchanted stacks should not be similar", noTag.isSimilar(enchanted), is(false));
         assertThat("noTag and enchanted stacks should not be equal", noTag.equals(enchanted), is(false));
+
+        // Paper start - test additional ItemMeta damage cases
+        ItemStack clone = CraftItemStack.asBukkitCopy(CraftItemStack.asNMSCopy(noDamage));
+        assertThat("Bukkit and craft stacks should be similar", noDamage.isSimilar(clone), is(true));
+        assertThat("Bukkit and craft stacks should be equal", noDamage.equals(clone), is(true));
+
+        ItemStack pureBukkit = new ItemStack(Material.DIAMOND_SWORD);
+        pureBukkit.setDurability((short) 2);
+        net.minecraft.server.ItemStack nms = CraftItemStack.asNMSCopy(pureBukkit);
+        ItemStack other = CraftItemStack.asBukkitCopy(nms);
+
+        assertThat("Bukkit and NMS ItemStack copies should be similar", pureBukkit.isSimilar(other), is(true));
+        assertThat("Bukkit and NMS ItemStack copies should be equal", pureBukkit.equals(other), is(true));
+    }
+
+    private void testItemMeta(ItemStack stack) {
+        assertThat("Should not have ItemMeta", stack.hasItemMeta(), is(false));
+
+        stack.setDurability((short) 0);
+        assertThat("ItemStack with zero durability should not have ItemMeta", stack.hasItemMeta(), is(false));
+
+        stack.setDurability((short) 2);
+        assertThat("ItemStack with non-zero durability should have ItemMeta", stack.hasItemMeta(), is(true));
+
+        stack.setLore(Collections.singletonList("Lore"));
+        assertThat("ItemStack with lore and durability should have ItemMeta", stack.hasItemMeta(), is(true));
+
+        stack.setDurability((short) 0);
+        assertThat("ItemStack with lore should have ItemMeta", stack.hasItemMeta(), is(true));
+
+        stack.setLore(null);
+    }
+
+    @Test
+    public void testHasItemMeta() {
+        ItemStack itemStack = new ItemStack(Material.SHEARS);
+
+        testItemMeta(itemStack);
+        testItemMeta(CraftItemStack.asCraftCopy(itemStack));
     }
+    // Paper end
 
     @Test
     public void testBlockStateMeta() {
-- 
2.21.0