Alpha 5 regression: Custom class typed array is broken.

[nabfrew]

Godot version

v4.0.alpha5.official [d7d528c]

System information

Windows 10

Issue description

When a function returning Array[CustomClass] to a variable expecting Array[CustomClass], the following error occurs:

'Trying to return a typed array with an array of different type.'

E 0:00:00:0829   _ready: Assignment of arrays of incompatible types.
  <C++ Error>    Method/function failed. Returning: false
  <C++ Source>   core/variant/array.cpp:221 @ _assign()
  <Stack Trace>  Node2D.gd:13 @ func_that_returns_custom_array()
                 Node2D.gd:6 @ _ready()

This worked fine on alpha 4. If you push past the breakpoint at the error, nothing is assigned to the variable.

Steps to reproduce

extends Node2D

func _ready() -> void:
	var int_array : Array[int] = func_that_returns_int_array()
	print(int_array)
	var custom_array : Array[CustomClass] = func_that_returns_custom_array()
	print(custom_array[0].number)
	
func func_that_returns_int_array() -> Array[int]:
	return [0, 1, 2]
	
func func_that_returns_custom_array() -> Array[CustomClass]:
	return [CustomClass.new(3), CustomClass.new(4), CustomClass.new(5)]

with a custom class, e.g.:

extends Node

class_name CustomClass

var number : int

func _init(n : int) -> void:
	number = n

Minimal reproduction project

CustomTypedArrayBug.zip

[nabfrew]

Don't know what changed, but this is fixed in Alpha 6.

[nabfrew]

Sorry, my mistake, it wasn't fixed, I just opened the wrong version of the reproduction project with bits commented out.

[nabfrew]

Two findings on further inspecting the bug:

• The error is caused by the hint in the function return type, has nothing to do with the variable the function's return value is assigned to. i.e. func return_array() -> Array[CustomClass]: causes error, func return_array(): does not.
• if you create an array of a custom type, custom_array, it's a String array according to typeof(custom_array)...