Fixing isLocalInstanceAuthoritative and getKnownMovement for EntityPlayerMPFakes (#2176)

Fixes:
- At least some spear attacks
- Mace attacks (not verified myself)
- Fall damage (#2198)

Possibly needs further checking that isLocalInstanceAuthoritative doesn't break other things, but I don't have the time right now.

Co-authored-by: altrisi <altrisi.trillosierra@gmail.com>

src/main/java/carpet/mixins/EntityMixin.java

@@ -38,7 +38,8 @@ public abstract class EntityMixin implements EntityInterface
     @Inject(method = "isLocalInstanceAuthoritative", at = @At("HEAD"), cancellable = true)
     private void isFakePlayer(CallbackInfoReturnable<Boolean> cir)
     {
-        if (getControllingPassenger() instanceof EntityPlayerMPFake) cir.setReturnValue(!level.isClientSide());
+        // getControllingPassenger() does not return the EntityPlayerMPFake if there are no passengers involved with it
+        if ((Object) this instanceof EntityPlayerMPFake || getControllingPassenger() instanceof EntityPlayerMPFake) cir.setReturnValue(!level.isClientSide());
     }
 
     @Shadow

src/main/java/carpet/mixins/ServerPlayer_fakeLastMovementMixin.java

@@ -0,0 +1,33 @@
+package carpet.mixins;
+
+import org.objectweb.asm.Opcodes;
+import org.spongepowered.asm.mixin.Debug;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import com.llamalad7.mixinextras.injector.ModifyExpressionValue;
+import com.mojang.authlib.GameProfile;
+
+import carpet.patches.EntityPlayerMPFake;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.Vec3;
+
+@Mixin(ServerPlayer.class)
+@Debug(export = true)
+public abstract class ServerPlayer_fakeLastMovementMixin extends Player {
+    public ServerPlayer_fakeLastMovementMixin(Level level, GameProfile gameProfile) {
+        super(level, gameProfile);
+        throw new AssertionError();
+    }
+
+    @ModifyExpressionValue(
+        method = {"getKnownMovement", "getKnownSpeed"}, // both because ServerPlayer overrides both to the same "movement" field
+        at = @At(value = "FIELD", target = "lastKnownClientMovement", opcode = Opcodes.GETFIELD),
+        require = 2
+    )
+    private Vec3 bypassClientMovementInfo(Vec3 original) {
+        return ((Player)this) instanceof EntityPlayerMPFake ? super.getKnownMovement() : original;
+    }
+}

src/main/java/carpet/patches/EntityPlayerMPFake.java

@@ -267,11 +267,6 @@ public class EntityPlayerMPFake extends ServerPlayer
         return CarpetSettings.allowListingFakePlayers;
     }
 
-    @Override
-    protected void checkFallDamage(double y, boolean onGround, BlockState state, BlockPos pos) {
-        doCheckFallDamage(0.0, y, 0.0, onGround);
-    }
-
     @Override
     public ServerPlayer teleport(TeleportTransition serverLevel)
     {

src/main/resources/carpet.mixins.json

@@ -49,6 +49,7 @@
     "MobMixin",
     "Villager_aiMixin",
     "Player_fakePlayersMixin",
+	"ServerPlayer_fakeLastMovementMixin",
     "TickRateManager_fakePlayersMixin",
     "ServerGamePacketListenerImpl_coreMixin",
     "MinecraftServer_scarpetMixin",