GDScript 2.0: Type casting (as) not working with typed arrays

[Scony]

Godot version

4.0.dev.custom_build.3bebbcacd

System information

manjaro linux

Issue description

print([1,2.1] as Array[int])

yields

[1, 2.1]

while it should cast elements to int I believe.

Steps to reproduce

Run the above.

Minimal reproduction project

No response

[dalexeev]

In 4.0.3 this works for constants and literals, but the bug remains for variables. In fact, the as operator only works correctly with objects, it has always worked inconsistently with Variant types (raises a runtime error instead of returning a default value), we should probably change this behavior.

print(var_to_str([1, 2.1] as Array[int])) # Array[int]([1, 2])
var x = [1, 2.1]
print(var_to_str(x as Array[int])) # [1, 2.1]
var y: Array[float] = [1, 2.1]
print(var_to_str(x as Array[int])) # [1, 2.1]

Also note the difference between casting and conversion, as should not convert an array at runtime and creating a new one (except if no conversion is possible), it should allow the static analyzer to change the type interpretation. For conversion, there is Array.assign() method and there is PR #71336 for a typed constructor.

[dalexeev]

• See also Behavior of typed arrays godot-proposals#7364.

We have not resolved all the design issues of typed arrays, but I don’t think that type casting should not create new data, only change the static type of the expression (when casting to a supertype) and provide a safe value in case of a type mismatch at runtime (when casting to a subtype). However, we introduced this behavior for array literals.

In any case, we cannot move forward until a consensus is found in the discussion. It would be nice to document the current implementation, but I don't think it's urgent.