From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Tue, 22 Dec 2020 22:41:12 +0000
Subject: [PATCH] Do not perform neighbour updates when using debug stick

CB blindly drops any update flags when recording block modifications,
this causes the debug stick to blindly update neighbouring blocks on usage
in order to control this, we will special case this item, however, this
ideally should be fixed by recording the actual update flags used,
but will induce ABI breaks...

This patch also maintains the behavior of the BlockPlaceEvent, this
behavior will NOT be guaranteed in the future, however.

diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
index 3adb29f004d2fee36f3ee9b21ee5417e84b64837..5a62ac72edc49cd032cd02fa8d007959517d063b 100644
--- a/src/main/java/net/minecraft/server/ItemStack.java
+++ b/src/main/java/net/minecraft/server/ItemStack.java
@@ -211,6 +211,7 @@ public final class ItemStack {
     }
 
     public EnumInteractionResult placeItem(ItemActionContext itemactioncontext, EnumHand enumhand) { // CraftBukkit - add hand
+        boolean doPhysicsUpdate = true; // Paper
         EntityHuman entityhuman = itemactioncontext.getEntity();
         BlockPosition blockposition = itemactioncontext.getClickPosition();
         ShapeDetectorBlock shapedetectorblock = new ShapeDetectorBlock(itemactioncontext.getWorld(), blockposition, false);
@@ -228,7 +229,11 @@ public final class ItemStack {
                 // special case bonemeal
                 if (this.getItem() == Items.BONE_MEAL) {
                     world.captureTreeGeneration = true;
+                    // Paper start
+                } else if (this.getItem() instanceof ItemDebugStick) {
+                    doPhysicsUpdate = false;
                 }
+                // Paper end
             }
             Item item = this.getItem();
             EnumInteractionResult enuminteractionresult = item.a(itemactioncontext);
@@ -316,7 +321,7 @@ public final class ItemStack {
                             block.getBlock().onPlace(block, world, newblockposition, oldBlock, true, itemactioncontext); // Paper - pass itemactioncontext
                         }
 
-                        world.notifyAndUpdatePhysics(newblockposition, null, oldBlock, block, world.getType(newblockposition), updateFlag, 512); // send null chunk as chunk.k() returns false by this point
+                        world.notifyAndUpdatePhysics(newblockposition, null, oldBlock, block, world.getType(newblockposition), updateFlag, 512 ^ (doPhysicsUpdate ? 0 : 16)); // send null chunk as chunk.k() returns false by this point // Paper
                     }
 
                     // Special case juke boxes as they update their tile entity. Copied from ItemRecord.