Spyglasses stay in use in spectator mode

Can confirm in 21w17a.

Can confirm in 1.17.

Can confirm in 1.17.1.

I can confirm this behavior in 1.18 Pre-release 4. Here are some extra details regarding this problem.

The Bug:

Players in spectator mode continue to use spyglasses shortly after switching game modes.

Steps to Reproduce:

• Obtain a spyglass.

• Use the spyglass and as your doing this, switch into spectator mode by pressing F3 + N.

• Take note as to whether or not you continue to use spyglasses shortly after switching game modes.

Observed Behavior:

Players in spectator mode continue to use spyglasses shortly after switching game modes.

Expected Behavior:

Players in spectator mode would not continue to use spyglasses shortly after switching game modes.

Can confirm in 1.18.

Can confirm in 1.18.1.

Here's a code analysis along with a fix regarding this issue.

Code Analysis:

The following is based on a decompiled version of Minecraft 1.19.2 using MCP-Reborn.

net.minecraft.server.level.ServerPlayer.java

public class ServerPlayer extends Player {
   ...
   public boolean setGameMode(GameType gameType) {
      if (!this.gameMode.changeGameModeForPlayer(gameType)) {
         return false;
      } else {
         this.connection.send(new ClientboundGameEventPacket(ClientboundGameEventPacket.CHANGE_GAME_MODE, (float)gameType.getId()));
         if (gameType == GameType.SPECTATOR) {
            this.removeEntitiesOnShoulder();
            this.stopRiding();
         } else {
            this.setCamera(this);
         }

         this.onUpdateAbilities();
         this.updateEffectVisibility();
         return true;
      }
   }
   ...

If we look at the above class, we can see that only two methods are called when a player switches into spectator mode. These methods are removeEntitiesOnShoulder() and stopRiding(). This basically means that when a player changes into spectator mode, any entities that are riding on their shoulders will be dismounted, along with the player themselves being dismounted if they are riding any entity. As a result of only these two methods being called, the player can continue to use items even after switching into spectator mode.

Fix:

Simply calling the stopUsingItem() method where appropriate within this piece of code will stop players from using items upon switching into spectator mode, thus resolving this problem. The following line code can be used to fix this issue.

this.stopUsingItem();