Make FlowerPotBlock extensible and reusable for mods

- Change static lookup map to an instance variable
- Add an instance variable for the "empty pot" for the current block
- Keep one instance of the lookup map between the empty pot and all its full versions
- Convert everything to use delegates

patches/minecraft/net/minecraft/block/FlowerPotBlock.java.patch

@@ -1,11 +1,88 @@
 --- a/net/minecraft/block/FlowerPotBlock.java
 +++ b/net/minecraft/block/FlowerPotBlock.java
-@@ -19,7 +19,7 @@
+@@ -19,14 +19,35 @@
  import net.minecraft.world.World;
  
  public class FlowerPotBlock extends Block {
 -   private static final Map<Block, Block> field_196451_b = Maps.newHashMap();
-+   private static final Map<Block, Block> field_196451_b = Maps.newHashMap();  //TODO: Delegates
     protected static final VoxelShape field_196450_a = Block.func_208617_a(5.0D, 0.0D, 5.0D, 11.0D, 6.0D, 11.0D);
-    private final Block field_196452_c;
+-   private final Block field_196452_c;
++   private final FlowerPotBlock emptyPot;
++   private final Map<net.minecraftforge.registries.IRegistryDelegate<Block>, net.minecraftforge.registries.IRegistryDelegate<Block>> fullPots;
++   private final net.minecraftforge.registries.IRegistryDelegate<Block> field_196452_c;
  
++   @Deprecated // Mods should use the constructor below
+    public FlowerPotBlock(Block p_i48395_1_, Block.Properties p_i48395_2_) {
++      this((FlowerPotBlock) Blocks.field_150457_bL, p_i48395_1_, p_i48395_2_);
++   }
++
++   /**
++    * For mod use, eliminates the need to extend this class, and prevents modded
++    * flower pots from altering vanilla behavior.
++    * 
++    * @param emptyPot    The empty pot for this pot, or null for self.
++    * @param p_i48395_1_ The flower block.
++    * @param p_i48395_2_
++    */
++   public FlowerPotBlock(FlowerPotBlock emptyPot, Block p_i48395_1_, Block.Properties p_i48395_2_) {
+       super(p_i48395_2_);
+-      this.field_196452_c = p_i48395_1_;
+-      field_196451_b.put(p_i48395_1_, this);
++      this.field_196452_c = p_i48395_1_.delegate;
++      if (emptyPot == null) {
++         this.fullPots = Maps.newHashMap();
++         this.emptyPot = this;
++      } else {
++         this.emptyPot = emptyPot;
++         this.fullPots = emptyPot.fullPots;
++         this.fullPots.put(p_i48395_1_.delegate, this.delegate);
++      }
+    }
+ 
+    public VoxelShape func_220053_a(BlockState p_220053_1_, IBlockReader p_220053_2_, BlockPos p_220053_3_, ISelectionContext p_220053_4_) {
+@@ -40,9 +61,9 @@
+    public boolean func_220051_a(BlockState p_220051_1_, World p_220051_2_, BlockPos p_220051_3_, PlayerEntity p_220051_4_, Hand p_220051_5_, BlockRayTraceResult p_220051_6_) {
+       ItemStack itemstack = p_220051_4_.func_184586_b(p_220051_5_);
+       Item item = itemstack.func_77973_b();
+-      Block block = item instanceof BlockItem ? field_196451_b.getOrDefault(((BlockItem)item).func_179223_d(), Blocks.field_150350_a) : Blocks.field_150350_a;
++      Block block = item instanceof BlockItem ? fullPots.getOrDefault(((BlockItem)item).func_179223_d().delegate, Blocks.field_150350_a.delegate).get() : Blocks.field_150350_a;
+       boolean flag = block == Blocks.field_150350_a;
+-      boolean flag1 = this.field_196452_c == Blocks.field_150350_a;
++      boolean flag1 = this.field_196452_c.get() == Blocks.field_150350_a;
+       if (flag != flag1) {
+          if (flag1) {
+             p_220051_2_.func_180501_a(p_220051_3_, block.func_176223_P(), 3);
+@@ -51,14 +72,14 @@
+                itemstack.func_190918_g(1);
+             }
+          } else {
+-            ItemStack itemstack1 = new ItemStack(this.field_196452_c);
++            ItemStack itemstack1 = new ItemStack(this.field_196452_c.get());
+             if (itemstack.func_190926_b()) {
+                p_220051_4_.func_184611_a(p_220051_5_, itemstack1);
+             } else if (!p_220051_4_.func_191521_c(itemstack1)) {
+                p_220051_4_.func_71019_a(itemstack1, false);
+             }
+ 
+-            p_220051_2_.func_180501_a(p_220051_3_, Blocks.field_150457_bL.func_176223_P(), 3);
++            p_220051_2_.func_180501_a(p_220051_3_, emptyPot.func_176223_P(), 3);
+          }
+       }
+ 
+@@ -66,7 +87,7 @@
+    }
+ 
+    public ItemStack func_185473_a(IBlockReader p_185473_1_, BlockPos p_185473_2_, BlockState p_185473_3_) {
+-      return this.field_196452_c == Blocks.field_150350_a ? super.func_185473_a(p_185473_1_, p_185473_2_, p_185473_3_) : new ItemStack(this.field_196452_c);
++      return this.field_196452_c.get() == Blocks.field_150350_a ? super.func_185473_a(p_185473_1_, p_185473_2_, p_185473_3_) : new ItemStack(this.field_196452_c.get());
+    }
+ 
+    public BlockState func_196271_a(BlockState p_196271_1_, Direction p_196271_2_, BlockState p_196271_3_, IWorld p_196271_4_, BlockPos p_196271_5_, BlockPos p_196271_6_) {
+@@ -78,6 +99,6 @@
+    }
+ 
+    public Block func_220276_d() {
+-      return this.field_196452_c;
++      return this.field_196452_c.get();
+    }
+ }

src/main/resources/forge.exc

@@ -1,5 +1,5 @@
 net/minecraft/block/FireBlock.tryCatchFire(Lnet/minecraft/world/World;Lnet/minecraft/util/math/BlockPos;ILjava/util/Random;ILnet/minecraft/util/Direction;)V=|p_176536_1_,p_176536_2_,p_176536_3_,p_176536_4_,p_176536_5_,face
-
+net/minecraft/block/FlowerPotBlock.<init>(Lnet/minecraft/block/FlowerPotBlock;Lnet/minecraft/block/Block;Lnet/minecraft/block/Block$Properties;)V=|emptyPot,p_i48395_1_,p_i48395_2_
 net/minecraft/block/RedstoneWireBlock.canConnectTo(Lnet/minecraft/block/BlockState;Lnet/minecraft/world/IBlockReader;Lnet/minecraft/util/math/BlockPos;Lnet/minecraft/util/Direction;)Z=|p_176343_0_,world,pos,p_176343_1_
 
 net/minecraft/block/PoweredRailBlock.<init>(Lnet/minecraft/block/Block$Properties;Z)=|p_i48349_1_,isActivator

src/test/java/net/minecraftforge/debug/block/FlowerPotTest.java

@@ -0,0 +1,59 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.debug.block;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.Blocks;
+import net.minecraft.block.FlowerPotBlock;
+import net.minecraft.item.BlockItem;
+import net.minecraft.item.Item;
+import net.minecraftforge.event.RegistryEvent;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.Mod.EventBusSubscriber.Bus;
+import net.minecraftforge.registries.ObjectHolder;
+
+@Mod(FlowerPotTest.MODID)
+@Mod.EventBusSubscriber(bus = Bus.MOD)
+public class FlowerPotTest
+{
+    static final String MODID = "flower_pot_test";
+    static final String BLOCK_ID = "test_flower_pot";
+
+    @ObjectHolder(BLOCK_ID)
+    public static FlowerPotBlock EMPTY_FLOWER_POT;
+
+    @ObjectHolder(BLOCK_ID)
+    public static FlowerPotBlock OAK_FLOWER_POT;
+
+    @SubscribeEvent
+    public static void registerBlocks(RegistryEvent.Register<Block> event)
+    {
+        FlowerPotBlock empty = new FlowerPotBlock(null, Blocks.AIR, Block.Properties.from(Blocks.FLOWER_POT));
+        event.getRegistry().register(empty.setRegistryName(BLOCK_ID));
+        event.getRegistry().register(new FlowerPotBlock(empty, Blocks.OAK_SAPLING, Block.Properties.from(empty)).setRegistryName(BLOCK_ID + "_oak"));
+    }
+
+    @SubscribeEvent
+    public static void registerItems(RegistryEvent.Register<Item> event)
+    {
+        event.getRegistry().register(new BlockItem(EMPTY_FLOWER_POT, new Item.Properties()).setRegistryName(MODID, BLOCK_ID));
+    }
+}

src/test/java/net/minecraftforge/debug/block/StickyBlockTest.java

@@ -27,10 +27,11 @@ import net.minecraft.item.Item;
 import net.minecraftforge.event.RegistryEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.Mod.EventBusSubscriber.Bus;
 import net.minecraftforge.registries.ObjectHolder;
 
 @Mod(StickyBlockTest.MODID)
-@Mod.EventBusSubscriber
+@Mod.EventBusSubscriber(bus = Bus.MOD)
 public class StickyBlockTest
 {
     static final String MODID = "custom_slime_block_test";

src/test/resources/META-INF/mods.toml

@@ -51,3 +51,5 @@ loaderVersion="[28,)"
     modId="data_gen_test"
 [[mods]]
     modId="piston_event_test"
+[[mods]]
+    modId="flower_pot_test"

src/test/resources/assets/flower_pot_test/blockstates/test_flower_pot.json

@@ -0,0 +1,5 @@
+{
+    "variants": {
+        "": { "model": "block/flower_pot" }
+    }
+}

src/test/resources/assets/flower_pot_test/blockstates/test_flower_pot_oak.json

@@ -0,0 +1,5 @@
+{
+    "variants": {
+        "": { "model": "block/potted_oak_sapling" }
+    }
+}

src/test/resources/assets/flower_pot_test/models/item/test_flower_pot.json

@@ -0,0 +1,6 @@
+{
+    "parent": "item/generated",
+    "textures": {
+        "layer0": "item/flower_pot"
+    }
+}