Add registry context to LootTableLoadEvent

patches/net/minecraft/server/ReloadableServerRegistries.java.patch

@@ -1,7 +1,10 @@
 --- a/net/minecraft/server/ReloadableServerRegistries.java
 +++ b/net/minecraft/server/ReloadableServerRegistries.java
-@@ -61,8 +_,16 @@
+@@ -59,10 +_,19 @@
+     ) {
+         return CompletableFuture.supplyAsync(
              () -> {
++                var provider = net.neoforged.neoforge.common.CommonHooks.extractLookupProvider(p_336173_);
                  WritableRegistry<T> writableregistry = new MappedRegistry<>(p_335741_.registryKey(), Lifecycle.experimental());
                  Map<ResourceLocation, T> map = new HashMap<>();
 +                Map<ResourceLocation, Optional<T>> optionalMap = new HashMap<>();
@@ -11,7 +14,7 @@
 +                optionalMap.forEach((rl, optionalEntry) -> {
 +                    optionalEntry.ifPresent(entry -> p_335741_.idSetter().accept(entry, rl));
 +                    T value = optionalEntry.orElse(p_335741_.defaultValue());
-+                    if (value instanceof LootTable lootTable) value = (T) net.neoforged.neoforge.event.EventHooks.loadLootTable(rl, lootTable);
++                    if (value instanceof LootTable lootTable) value = (T) net.neoforged.neoforge.event.EventHooks.loadLootTable(rl, lootTable, provider);
 +                    if (value != null)
 +                    map.put(rl, value);
 +                });

src/main/java/net/neoforged/neoforge/common/CommonHooks.java

@@ -65,6 +65,7 @@
 import net.minecraft.network.protocol.game.ClientboundBlockUpdatePacket;
 import net.minecraft.network.protocol.game.ServerboundPlayerActionPacket;
 import net.minecraft.network.syncher.EntityDataSerializer;
+import net.minecraft.resources.RegistryOps;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.MinecraftServer;
@@ -1524,6 +1525,18 @@ public static <T> RegistryLookup<T> resolveLookup(ResourceKey<? extends Registry
         return null;
     }
 
+    /**
+     * Extracts a {@link HolderLookup.Provider} from the given {@code ops}, if possible.
+     *
+     * @throws IllegalArgumentException if the ops were not created using a {@linkplain HolderLookup.Provider}
+     */
+    public static HolderLookup.Provider extractLookupProvider(RegistryOps<?> ops) {
+        if (ops.lookupProvider instanceof RegistryOps.HolderLookupAdapter hla) {
+            return hla.lookupProvider;
+        }
+        throw new IllegalArgumentException("Registry ops has lookup provider " + ops.lookupProvider + " which is not a HolderLookupAdapter");
+    }
+
     /**
      * Creates a {@link UseOnContext} for {@link net.minecraft.core.dispenser.DispenseItemBehavior dispense behavior}.
      *

src/main/java/net/neoforged/neoforge/event/EventHooks.java

@@ -26,6 +26,7 @@
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.core.Holder;
+import net.minecraft.core.HolderLookup;
 import net.minecraft.core.HolderLookup.RegistryLookup;
 import net.minecraft.core.NonNullList;
 import net.minecraft.core.RegistryAccess;
@@ -688,10 +689,11 @@ public static boolean onProjectileImpact(Projectile projectile, HitResult ray) {
      * which maps to an empty {@link Optional} in {@link LootDataType#deserialize(ResourceLocation, DynamicOps, Object)}
      */
     @Nullable
-    public static LootTable loadLootTable(ResourceLocation name, LootTable table) {
+    @ApiStatus.Internal
+    public static LootTable loadLootTable(ResourceLocation name, LootTable table, HolderLookup.Provider registries) {
         if (table == LootTable.EMPTY) // Empty table has a null name, and shouldn't be modified anyway.
             return null;
-        LootTableLoadEvent event = new LootTableLoadEvent(name, table);
+        LootTableLoadEvent event = new LootTableLoadEvent(registries, name, table);
         if (NeoForge.EVENT_BUS.post(event).isCanceled() || event.getTable() == LootTable.EMPTY)
             return null;
         return event.getTable();

src/main/java/net/neoforged/neoforge/event/LootTableLoadEvent.java

@@ -6,12 +6,17 @@
 package net.neoforged.neoforge.event;
 
 import java.util.Objects;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.level.storage.loot.LootTable;
 import net.neoforged.bus.api.Event;
 import net.neoforged.bus.api.ICancellableEvent;
 import net.neoforged.fml.LogicalSide;
 import net.neoforged.neoforge.common.NeoForge;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Fired when a {@link LootTable} is loaded from JSON.
@@ -26,16 +31,36 @@
  * only on the {@linkplain LogicalSide#SERVER logical server}.</p>
  */
 public class LootTableLoadEvent extends Event implements ICancellableEvent {
+    private final HolderLookup.Provider registries;
     private final ResourceLocation name;
     private LootTable table;
 
-    public LootTableLoadEvent(ResourceLocation name, LootTable table) {
+    @Nullable
+    private ResourceKey<LootTable> key;
+
+    @ApiStatus.Internal
+    public LootTableLoadEvent(HolderLookup.Provider registries, ResourceLocation name, LootTable table) {
+        this.registries = registries;
         this.name = name;
         this.table = table;
     }
 
+    /**
+     * {@return a lookup provider that can be used to access registries}
+     */
+    public HolderLookup.Provider getRegistries() {
+        return registries;
+    }
+
     public ResourceLocation getName() {
-        return this.name;
+        return name;
+    }
+
+    public ResourceKey<LootTable> getKey() {
+        if (this.key == null) {
+            this.key = ResourceKey.create(Registries.LOOT_TABLE, name);
+        }
+        return this.key;
     }
 
     public LootTable getTable() {

src/main/resources/META-INF/accesstransformer.cfg

@@ -158,6 +158,9 @@ public net.minecraft.gametest.framework.GameTestHelper testInfo # testInfo
 public net.minecraft.gametest.framework.GameTestInfo sequences # sequences
 public net.minecraft.gametest.framework.GameTestSequence <init>(Lnet/minecraft/gametest/framework/GameTestInfo;)V # <init>
 protected net.minecraft.resources.RegistryOps <init>(Lcom/mojang/serialization/DynamicOps;Lnet/minecraft/resources/RegistryOps$RegistryInfoLookup;)V # constructor
+public net.minecraft.resources.RegistryOps lookupProvider
+public net.minecraft.resources.RegistryOps$HolderLookupAdapter
+public net.minecraft.resources.RegistryOps$HolderLookupAdapter lookupProvider
 public net.minecraft.resources.ResourceLocation validNamespaceChar(C)Z # validNamespaceChar
 protected net.minecraft.server.MinecraftServer nextTickTimeNanos # nextTickTimeNanos
 public net.minecraft.server.MinecraftServer$ReloadableResources

tests/src/main/java/net/neoforged/neoforge/debug/loot/LootPoolTest.java

@@ -92,7 +92,7 @@ static void pinkConcreteLootTableCanceled(final DynamicTest test, final Registra
                 event.getLookupProvider()));
 
         NeoForge.EVENT_BUS.addListener((final LootTableLoadEvent event) -> {
-            if (event.getName().equals(lootTableToUse.location())) {
+            if (event.getKey() == lootTableToUse) {
                 event.setCanceled(true);
             }
         });
@@ -131,7 +131,7 @@ static void orangeConcreteLootTableReplaced(final DynamicTest test, final Regist
                 event.getLookupProvider()));
 
         NeoForge.EVENT_BUS.addListener((final LootTableLoadEvent event) -> {
-            if (event.getName().equals(lootTableToUse.location())) {
+            if (event.getKey() == lootTableToUse) {
                 LootPoolSingletonContainer.Builder<?> entry = LootItem.lootTableItem(Items.BLUE_CONCRETE);
                 LootPool.Builder pool = LootPool.lootPool().setRolls(ConstantValue.exactly(1)).add(entry).when(ExplosionCondition.survivesExplosion());
                 event.setTable(new LootTable.Builder().withPool(pool).build());
@@ -172,7 +172,7 @@ static void yellowConcreteLootTableAppended(final DynamicTest test, final Regist
                 event.getLookupProvider()));
 
         NeoForge.EVENT_BUS.addListener((final LootTableLoadEvent event) -> {
-            if (event.getName().equals(lootTableToUse.location())) {
+            if (event.getKey() == lootTableToUse) {
                 LootPoolSingletonContainer.Builder<?> entry = LootItem.lootTableItem(Items.YELLOW_CONCRETE);
                 LootPool.Builder pool = LootPool.lootPool().setRolls(ConstantValue.exactly(1)).add(entry).when(ExplosionCondition.survivesExplosion());
                 event.getTable().addPool(pool.build());