TypedArray argument is copied

[pkdawson]

Godot version

v4.1.beta2.mono.official [a2575cba4]

godot-cpp version

82edc89

System information

Windows 11 22H2

Issue description

If my method takes an Array parameter, it behaves as a reference to the original array which was passed in from GDScript, so it can be modified.

But if I change that to a TypedArray, the array is instead copied, and any changes are therefore lost.

void MyObject::AppendToArray(Array a)
{
    // works as expected
    a.append(100);
}

void MyObject::AppendToTypedArray(TypedArray<int> b)
{
    // original array is unchanged
    b.append(200);
}

var a = []
var b: Array[int] = []

MyObject.AppendToArray(a)
MyObject.AppendToTypedArray(b)

print(a) # [100]
print(b) # []

This is because the TypedArray constructors call a builtin Array constructor which makes a copy.

godot-cpp/include/godot_cpp/variant/typed_array.hpp

Lines 67 to 72 in 82edc89

	_FORCE_INLINE_ TypedArray(const Variant &p_variant) : \
	Array(p_variant.operator Array(), m_variant_type, StringName(), Variant()) { \
	} \
	_FORCE_INLINE_ TypedArray(const Array &p_array) : \
	Array(p_array, m_variant_type, StringName(), Variant()) { \
	} \

https://github.com/godotengine/godot/blob/7b170d12cf0f8b3a15572fd203aa5cba840975f3/core/variant/array.cpp#L756-L761

If I change those base constructor calls to the single-argument Array constructor, it fixes the issue for me, but I'm not sure what the proper fix should be.

Steps to reproduce

Bind a method which takes a TypedArray parameter and modifies the array.

Minimal reproduction project

N/A

[AThousandShips]

See also:

• C++ A deep copy (COW) of TypedArray is sometimes incorrectly made godot#89191

This will be fixed after the same fix is applied in the engine itself:

• [Core] Fix sharing of typed arrays from constructor godot#89197

Edit: Pushed the godot-cpp version of the fix now, but it'll have to wait for the core fix I suspect