SPIGOT-7654: ItemStack#isSimilar does not work with empty BlockStateMeta

By: md_5 <git@md-5.net>

paper-server/nms-patches/net/minecraft/world/level/block/entity/TileEntity.patch

@@ -49,7 +49,18 @@
          return nbttagcompound;
      }
  
-@@ -265,7 +289,7 @@
+@@ -260,12 +284,18 @@
+     }
+ 
+     public final void applyComponents(DataComponentMap datacomponentmap, DataComponentPatch datacomponentpatch) {
++        // CraftBukkit start
++        this.applyComponentsSet(datacomponentmap, datacomponentpatch);
++    }
++
++    public final Set<DataComponentType<?>> applyComponentsSet(DataComponentMap datacomponentmap, DataComponentPatch datacomponentpatch) {
++        // CraftBukkit end
+         final Set<DataComponentType<?>> set = new HashSet();
+ 
          set.add(DataComponents.BLOCK_ENTITY_DATA);
          final PatchedDataComponentMap patcheddatacomponentmap = PatchedDataComponentMap.fromPatch(datacomponentmap, datacomponentpatch);
  
@@ -58,7 +69,18 @@
              @Nullable
              @Override
              public <T> T get(DataComponentType<T> datacomponenttype) {
-@@ -317,6 +341,15 @@
+@@ -283,6 +313,10 @@
+         DataComponentPatch datacomponentpatch1 = datacomponentpatch.forget(set::contains);
+ 
+         this.components = datacomponentpatch1.split().added();
++        // CraftBukkit start
++        set.remove(DataComponents.BLOCK_ENTITY_DATA); // Remove as never actually added by applyImplicitComponents
++        return set;
++        // CraftBukkit end
+     }
+ 
+     protected void collectImplicitComponents(DataComponentMap.a datacomponentmap_a) {}
+@@ -317,6 +351,15 @@
          }
      }
  

paper-server/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java

@@ -1,8 +1,10 @@
 package org.bukkit.craftbukkit.block;
 
+import java.util.Set;
 import net.minecraft.core.IRegistryCustom;
 import net.minecraft.core.component.DataComponentMap;
 import net.minecraft.core.component.DataComponentPatch;
+import net.minecraft.core.component.DataComponentType;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.network.protocol.Packet;
 import net.minecraft.network.protocol.game.PacketListenerPlayOut;
@@ -60,9 +62,10 @@ public class CraftBlockEntityState<T extends TileEntity> extends CraftBlockState
         return snapshot;
     }
 
-    public void applyComponents(DataComponentMap datacomponentmap, DataComponentPatch datacomponentpatch) {
+    public Set<DataComponentType<?>> applyComponents(DataComponentMap datacomponentmap, DataComponentPatch datacomponentpatch) {
-        snapshot.applyComponents(datacomponentmap, datacomponentpatch);
+        Set<DataComponentType<?>> result = snapshot.applyComponentsSet(datacomponentmap, datacomponentpatch);
         load(snapshot);
+        return result;
     }
 
     public DataComponentMap collectComponents() {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java

@@ -4,8 +4,6 @@ import com.google.common.base.Objects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Sets;
-import java.util.HashSet;
-import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 import net.minecraft.core.BlockPosition;
@@ -137,32 +135,6 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
             Material.VAULT
     );
 
-    private static final class TrackedDataComponentMap implements DataComponentMap {
-
-        private final Set<DataComponentType<?>> seen = new HashSet<>();
-        private final DataComponentMap handle;
-
-        public TrackedDataComponentMap(DataComponentMap map) {
-            this.handle = map;
-        }
-
-        @Override
-        public <T> T get(DataComponentType<? extends T> type) {
-            seen.add(type);
-            return handle.get(type);
-        }
-
-        @Override
-        public Set<DataComponentType<?>> keySet() {
-            return handle.keySet();
-        }
-
-        @Override
-        public Iterator<TypedDataComponent<?>> iterator() {
-            return handle.iterator();
-        }
-    }
-
     static {
         // Add shulker boxes to the list of block state materials too
         BLOCK_STATE_MATERIALS.addAll(SHULKER_BOX_MATERIALS);
@@ -198,6 +170,7 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
         });
 
         if (!tag.isEmpty()) {
+            CraftBlockEntityState<?> blockEntityTag = this.blockEntityTag;
             if (blockEntityTag == null) {
                 blockEntityTag = getBlockState(material, null);
             }
@@ -205,14 +178,16 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
             // Convert to map
             PatchedDataComponentMap map = new PatchedDataComponentMap(DataComponentMap.EMPTY);
             map.applyPatch(tag);
-            // Setup tracking
-            TrackedDataComponentMap track = new TrackedDataComponentMap(map);
             // Apply
-            blockEntityTag.applyComponents(track, tag);
+            Set<DataComponentType<?>> applied = blockEntityTag.applyComponents(map, tag);
             // Mark applied components as handled
-            for (DataComponentType<?> seen : track.seen) {
+            for (DataComponentType<?> seen : applied) {
                 unhandledTags.clear(seen);
             }
+            // Only set blockEntityTag if something was applied
+            if (!applied.isEmpty()) {
+                this.blockEntityTag = blockEntityTag;
+            }
         }
     }