Paper/patches/server/0935-Fix-creation-of-invalid-block-entity-during-world-ge.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Pierpaolo Coletta <p.coletta@glyart.com>
Date: Sat, 30 Mar 2024 21:06:10 +0100
Subject: [PATCH] Fix creation of invalid block entity during world generation


diff --git a/src/main/java/net/minecraft/server/level/WorldGenRegion.java b/src/main/java/net/minecraft/server/level/WorldGenRegion.java
index 2e72e92762877b28dd908711671e1dfb933de9b0..b7d29389a357f142237cecd75f8ca91cf1eb6b5b 100644
--- a/src/main/java/net/minecraft/server/level/WorldGenRegion.java
+++ b/src/main/java/net/minecraft/server/level/WorldGenRegion.java
@@ -324,7 +324,7 @@ public class WorldGenRegion implements WorldGenLevel {
             return false;
         } else {
             ChunkAccess ichunkaccess = this.getChunk(pos);
-            BlockState iblockdata1 = ichunkaccess.setBlockState(pos, state, false);
+            BlockState iblockdata1 = ichunkaccess.setBlockState(pos, state, false); final BlockState previousBlockState = iblockdata1; // Paper - Clear block entity before setting up a DUMMY block entity - obfhelper
 
             if (iblockdata1 != null) {
                 this.level.onBlockStateChange(pos, iblockdata1, state);
@@ -340,6 +340,17 @@ public class WorldGenRegion implements WorldGenLevel {
                         ichunkaccess.removeBlockEntity(pos);
                     }
                 } else {
+                    // Paper start - Clear block entity before setting up a DUMMY block entity
+                    // The concept of removing a block entity when the block itself changes is generally lifted
+                    // from LevelChunk#setBlockState.
+                    // It is however to note that this may only run if the block actually changes.
+                    // Otherwise a chest block entity generated by a structure template that is later "updated" to
+                    // be waterlogged would remove its existing block entity (see PaperMC/Paper#10750)
+                    // This logic is *also* found in LevelChunk#setBlockState.
+                    if (previousBlockState != null && !java.util.Objects.equals(previousBlockState.getBlock(), state.getBlock())) {
+                        ichunkaccess.removeBlockEntity(pos);
+                    }
+                    // Paper end - Clear block entity before setting up a DUMMY block entity
                     CompoundTag nbttagcompound = new CompoundTag();
 
                     nbttagcompound.putInt("x", pos.getX());
diff --git a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
index 7181acfafad91aa5f6ab7ce663d9be4a1b65b02a..5dd1df0da1f954778aebe0f40611ae0f3a7866ab 100644
--- a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
@@ -994,9 +994,14 @@ public class LevelChunk extends ChunkAccess {
                         if (this.blockEntity.getType().isValid(iblockdata)) {
                             this.ticker.tick(LevelChunk.this.level, this.blockEntity.getBlockPos(), iblockdata, this.blockEntity);
                             this.loggedInvalidBlockState = false;
-                        } else if (!this.loggedInvalidBlockState) {
-                            this.loggedInvalidBlockState = true;
-                            LevelChunk.LOGGER.warn("Block entity {} @ {} state {} invalid for ticking:", new Object[]{LogUtils.defer(this::getType), LogUtils.defer(this::getPos), iblockdata});
+                        // Paper start - Remove the Block Entity if it's invalid
+                        } else {
+                            LevelChunk.this.removeBlockEntity(this.getPos());
+                            if (!this.loggedInvalidBlockState) {
+                                this.loggedInvalidBlockState = true;
+                                LevelChunk.LOGGER.warn("Block entity {} @ {} state {} invalid for ticking:", new Object[]{LogUtils.defer(this::getType), LogUtils.defer(this::getPos), iblockdata});
+                            }
+                            // Paper end - Remove the Block Entity if it's invalid
                         }
 
                         gameprofilerfiller.pop();