creative_object_interface no longer can be used with castable_subtype due to lack of <castable> specifier

General Issues and Bug Reporting
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1

Summary

Providing a class which implements the creative_object_interface as a value for the type castable_subtype(creative_object_interface) does not work to properly cast different creative objects into devices, props, etc (common workflow when using Verse tags).

Please select what you are reporting on:

Verse

What Type of Bug are you experiencing?

Verse

Steps to Reproduce

Use this code in your project.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

(InDevice:creative_object_interface).CastTo(cast_type:castable_subtype(creative_object_interface))<transacts><decides>:cast_type =
    cast_type[InDevice]

TestFunction(InAgent:agent, InDevice:creative_object_interface):void =
    if(TriggerDevice := InDevice.CastTo[trigger_device]):
        TriggerDevice.Trigger(InAgent)

Expected Result

Compiles and works as expected. Assumption and understanding is that implementations of creative_object_interface should be <castable> but they are not. Perhaps some clarification could be provided.

Observed Result

Does not compile. If statement has LSP error: This function parameter expects a value of type tuple(creative_object_interface,castable_subtype(creative_object_interface)), but this argument is an incompatible value of type tuple(creative_object_interface,type(trigger_device, trigger_device))

Platform(s)

windows

Additional Notes

Removing the castable_ part from the parametric argument castable_subtype(creative_object_interface) fixes the issue. It compiles and properly casts. However, it is unclear if this type of behavior and syntax is intentional from Epic/Verse. As mentioned before: some clarification should be provided if this is unintentional or intentional etc.

Functional snippet:

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

(InDevice:creative_object_interface).CastTo(cast_type:castable_subtype(creative_object_interface))<transacts><decides>:cast_type =
    cast_type[InDevice]

TestFunction(InAgent:agent, InDevice:creative_object_interface):void =
    if(TriggerDevice := InDevice.CastTo[trigger_device]):
        TriggerDevice.Trigger(InAgent)
2

FORT-950079 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.

3

My proposition: remove castable and castable_subtype, leave subtype castable by default and we have some kind of simplification of the language instead of making it more complex every update.