[4.1.beta3][GDScript] Cannot call virtual function because it hasn't been defined.

[adamscott]

Godot version

4.1.beta3

System information

Fedora Workstation 38 - Godot 4.1.beta3 - Vulkan (Forward+)

Issue description

This is an issue created by the production team, we're working on it

Currently, it's impossible to call virtual functions within GDScript.

This currently returns an error:

# a.gd
extends Node

func _process(delta: float) -> void:
	pass

# main.gd
extends Node

var my_node: Node = preload("res://a.gd").new()

func _process(delta: float) -> void:
	my_node._process(delta)  # Cannot call virtual function "_process()" because it hasn't been defined.

Steps to reproduce

1. Create a script (a.gd) based on Node that declares _process();
2. Create a main node;
3. Attach a script to the main node;
4. Initialize a variable with a new a.gd instance;
5. Try to run _process() on that node;
6. Find out that it returns an error.

Minimal reproduction project

virtual_functions.zip (updated)

[anvilfolk]

I think this might mean we need to partially revert #77324, without any replacement 😞

The issue is that at compile-time we cannot check whether any Object, Node or otherwise, has a script attached. The script is the one responsible for implementing virtual functions, so the base type is simply not enough. I'll have a PR ready momentarily.