Mixin error: Cannot resolve method in target class

[SirEnder125]

Hey. I am trying to make a callback for the PlayerEntity class's kill() function. Here is my code:

import net.minecraft.client.MinecraftClient;
import net.minecraft.entity.EntityType;
import net.minecraft.entity.LivingEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.text.LiteralText;
import net.minecraft.world.World;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.injection.At;
import org.spongepowered.asm.mixin.injection.Inject;
import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;

@Mixin(PlayerEntity.class)
public abstract class PlayerEntityMixin extends LivingEntity
{
    protected PlayerEntityMixin(EntityType<? extends LivingEntity> entityType, World world)
    {
        super(entityType, world);
    }

    @Inject(at = @At("RETURN"), method = "Lnet/minecraft/entity/LivingEntity;kill()V")
    public void kill(CallbackInfo ci)
    {
        MinecraftClient.getInstance().player.sendMessage(new LiteralText("kill() called."), false);
    }
}

And here is the error that I get: Cannot resolve method 'Lnet/minecraft/entity/LivingEntity;kill()V' in target class

On running Minecraft Client:

Output

Exception in thread "main" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:236) at net.fabricmc.loader.launch.knot.Knot.launch(Knot.java:153) at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:28) at net.fabricmc.devlaunchinjector.Main.main(Main.java:86) Caused by: java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:567) at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:234) ... 3 more Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:208) at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:178) at org.spongepowered.asm.mixin.transformer.FabricMixinTransformerProxy.transformClassBytes(FabricMixinTransformerProxy.java:23) at net.fabricmc.loader.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:162) at net.fabricmc.loader.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:154) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519) at net.minecraft.client.main.Main.main(Main.java:129) ... 8 more Caused by: org.spongepowered.asm.mixin.throwables.MixinApplyError: Mixin [fabrictesting.mixins.json:PlayerEntityMixin] from phase [DEFAULT] in config [fabrictesting.mixins.json] FAILED during APPLY at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinError(MixinProcessor.java:642) at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinApplyError(MixinProcessor.java:594) at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:356) ... 15 more Caused by: org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException: @Inject annotation on kill specifies a target class 'net/minecraft/entity/LivingEntity', which is not supported [PREINJECT Applicator Phase -> fabrictesting.mixins.json:PlayerEntityMixin -> Prepare Injections -> -> handler$zhm000$kill(Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V -> Parse] at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.parseTargets(InjectionInfo.java:309) at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.readAnnotation(InjectionInfo.java:288) at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.(InjectionInfo.java:275) at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.(InjectionInfo.java:267) at org.spongepowered.asm.mixin.injection.struct.CallbackInjectionInfo.(CallbackInjectionInfo.java:46) at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:78) at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499) at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480) at org.spongepowered.asm.mixin.injection.struct.InjectionInfo$InjectorEntry.create(InjectionInfo.java:140) at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.parse(InjectionInfo.java:624) at org.spongepowered.asm.mixin.transformer.MixinTargetContext.prepareInjections(MixinTargetContext.java:1247) at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.prepareInjections(MixinApplicatorStandard.java:1033) at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyMixin(MixinApplicatorStandard.java:388) at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:320) at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:345) at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:569) at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:351) ... 15 more

[warjort]

The kill() method is in the LivingEntity class so you need:
@Mixin(LivingEntity.class)

If you just want it for player entities, you can override the method using normal java rules instead of an injection

@Mixin(PlayerEntity.class)
public abstract class PlayerEntityMixin extends LivingEntity  {
<snip/>
    @Override
    public void kill()
    {
        super.kill(); // LivingEntity.kill()
        MinecraftClient.getInstance().player.sendMessage(new LiteralText("kill() called."), false);
    }

But this might conflict with other mods if they do the same thing.

Also, the way you have written it doesn't work properly in general.
The kill() command runs on the server where MinecraftClient won't be available in dedicated server mode.

[SirEnder125]

Oh, lol. Alright. I was just using that code for an example of the error that I am getting. Thanks for the info. Also, could I use the LivingEntity class and check if this instanceof PlayerEntity? I am not experienced in the use of this keyword, so I am probably wrong.

[LlamaLad7]

Using instanceof is much better. The suggested answer will indeed conflict with other mods doing similar things.

[warjort]

Also, could I use the LivingEntity class and check if this instanceof PlayerEntity? I am not experienced in the use of this keyword, so I am probably wrong.

That's fine. Purists would say instanceof is a code smell (not proper OOP) but mixins aren't either.

[SirEnder125]

Oh, alright. Thanks again! :D

[SirEnder125]

For clarification, should I put this mixin in mixins, client, or server group in mixins.json?

[warjort]

For clarification, should I put this mixin in mixins, client, or server group in mixins.json?

As a rule of thumb, you should put it in "mixins" unless you know it only works on either the client (e.g. gui related) or the server.

[warjort]

unless you know it only works on either the client (e.g. gui related) or the server.

By server, I mean specific to dedicated server mode

[SirEnder125]

Alright. Thanks. :D Not sure when I would use dedicated server code, but I'll try to remember that.

[warjort]

Alright. Thanks. :D Not sure when I would use dedicated server code, but I'll try to remember that.

There are very few examples where dedicated server mode specific code is necessary.
One example is here:
https://github.com/FabricMC/fabric/blob/1.17/fabric-gametest-api-v1/src/main/java/net/fabricmc/fabric/mixin/gametest/server/MainMixin.java
which makes it easier to run fabric's own tests in dedicated server mode.