From eb8fe02a5ed96184ef47cfa50f00d5d4d2949a5f Mon Sep 17 00:00:00 2001
From: LexManos <LexManos@gmail.com>
Date: Wed, 13 Apr 2022 23:04:04 -0700
Subject: [PATCH] Fix intrusive handlers on dummy objects.

---
 .../registries/ForgeRegistry.java             | 25 +++++++++++++++++--
 .../minecraftforge/registries/GameData.java   |  2 +-
 .../registries/NamespacedHolderHelper.java    | 12 ++++++++-
 .../registries/RegistryManager.java           | 13 +++++++---
 4 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/src/main/java/net/minecraftforge/registries/ForgeRegistry.java b/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
index 3239ce03e8..657273679b 100644
--- a/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
+++ b/src/main/java/net/minecraftforge/registries/ForgeRegistry.java
@@ -876,6 +876,29 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
         if (this.dummyFactory == null)
             return false;
 
+        ForgeRegistry<V> active = RegistryManager.ACTIVE.getRegistry(getRegistryKey());
+        Optional<NamespacedHolderHelper<V>> holders = active.getHolderHelper();
+        if (holders.isPresent() && holders.get().isIntrusive() && holders.get().isFrozen())
+        {
+            try
+            {
+                // We have to unfreeze the ACTIVE registry because a lot of vanilla objects use intrusive handlers in object init.
+                holders.get().unfreeze();
+                createAndAddDummy(key, id);
+            }
+            finally
+            {
+                holders.get().freeze();
+            }
+        }
+        else
+            createAndAddDummy(key, id);
+
+        return true;
+    }
+
+    private void createAndAddDummy(ResourceLocation key, int id)
+    {
         V dummy = this.dummyFactory.createDummy(key);
         LOGGER.debug(REGISTRIES,"Registry {} Dummy Add: {} {} -> {}", this.name, key, id, dummy);
 
@@ -906,8 +929,6 @@ public class ForgeRegistry<V extends IForgeRegistryEntry<V>> implements IForgeRe
         if (realId != id)
             LOGGER.warn(REGISTRIES,"Registry {}: Object did not get ID it asked for. Name: {} Expected: {} Got: {}", this.name, key, id, realId);
         this.dummies.add(key);
-
-        return true;
     }
 
     //Public for tests
diff --git a/src/main/java/net/minecraftforge/registries/GameData.java b/src/main/java/net/minecraftforge/registries/GameData.java
index 9dd1632316..f58f39eb1b 100644
--- a/src/main/java/net/minecraftforge/registries/GameData.java
+++ b/src/main/java/net/minecraftforge/registries/GameData.java
@@ -737,7 +737,7 @@ public class GameData
             }
         }
 
-        RegistryManager STAGING = new RegistryManager("STAGING");
+        RegistryManager STAGING = new RegistryManager();
 
         final Map<ResourceLocation, Map<ResourceLocation, Integer[]>> remaps = Maps.newHashMap();
         final LinkedHashMap<ResourceLocation, Map<ResourceLocation, Integer>> missing = Maps.newLinkedHashMap();
diff --git a/src/main/java/net/minecraftforge/registries/NamespacedHolderHelper.java b/src/main/java/net/minecraftforge/registries/NamespacedHolderHelper.java
index c913272853..5c54bb3a1b 100644
--- a/src/main/java/net/minecraftforge/registries/NamespacedHolderHelper.java
+++ b/src/main/java/net/minecraftforge/registries/NamespacedHolderHelper.java
@@ -236,10 +236,20 @@ class NamespacedHolderHelper<T extends IForgeRegistryEntry<T>>
         this.frozen = false;
     }
 
+    boolean isFrozen()
+    {
+        return this.frozen;
+    }
+
+    boolean isIntrusive()
+    {
+        return this.holderLookup != null;
+    }
+
     @Nullable
     Holder<T> onAdded(RegistryManager stage, int id, T newValue, T oldValue)
     {
-        if (stage != RegistryManager.ACTIVE)
+        if (stage != RegistryManager.ACTIVE && (this.holderLookup == null || !stage.isStaging()))  // Intrusive handlers need updating in staging.
             return null; // Only do holder shit on the active registries, not pending or snapshots.
 
         ResourceKey<T> key = ResourceKey.create(this.self.key(), newValue.getRegistryName());
diff --git a/src/main/java/net/minecraftforge/registries/RegistryManager.java b/src/main/java/net/minecraftforge/registries/RegistryManager.java
index 5d0f455b94..486b0fb405 100644
--- a/src/main/java/net/minecraftforge/registries/RegistryManager.java
+++ b/src/main/java/net/minecraftforge/registries/RegistryManager.java
@@ -7,13 +7,11 @@ package net.minecraftforge.registries;
 
 import java.util.Collections;
 import java.util.HashMap;
-import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import com.google.common.collect.BiMap;
@@ -28,7 +26,6 @@ import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.core.Registry;
 import net.minecraftforge.fml.IModStateTransition;
-import net.minecraftforge.fml.ModContainer;
 import net.minecraftforge.network.HandshakeMessages;
 import net.minecraftforge.registries.ForgeRegistry.Snapshot;
 import org.apache.commons.lang3.tuple.Pair;
@@ -50,6 +47,11 @@ public class RegistryManager
     private Map<ResourceLocation, ResourceLocation> legacyNames = new HashMap<>();
     private final String name;
 
+    RegistryManager()
+    {
+        this("STAGING");
+    }
+
     public RegistryManager(String name)
     {
         this.name = name;
@@ -60,6 +62,11 @@ public class RegistryManager
         return this.name;
     }
 
+    boolean isStaging()
+    {
+        return "STAGING".equals(this.name);
+    }
+
     @SuppressWarnings("unchecked")
     public <V extends IForgeRegistryEntry<V>> Class<V> getSuperType(ResourceLocation key)
     {