Tree Execution Error When Setting `InputPort` Value to Empty String with `std::optional<T>` Default Value as `std::nullopt` After Commit 789ce6ea0ad3627923bd2389b8fb9199ffab6d84

[KentaKato]

Following the changes made in commit 789ce6e, an error occurs during tree execution when std::nullopt is set as the default value for an InputPort of type std::optional<T>, and the InputPort's value is subsequently set to an empty string ("").

This issue is exemplified when T is set to std::optional<geometry_msgs::Pose>, resulting in the following error message:

You (maybe indirectly) called BT::convertFromString() for type [std::optional<geometry_msgs::Pose_<std::allocator<void> > >], but I can't find the template specialization.

[ERROR] [1707813348.400082594]: [port_utils::getInput] Failed to get input 'poses': You didn't implement the template specialization of convertFromString for this type: std::optional<geometry_msgs::Pose_<std::allocator<void> > >
[ERROR] [1707813348.400098635]: [BT][InputTest][InputTest](UID 1): failed to get inputs

In Groot2, when an InputPort doesn't explicitly have a value assigned by the user, the system automatically assigns an empty string (""). However, this automatic assignment leads to runtime errors when the InputPort is of type std::optional with std::nullopt set as its default value. Ideally, the system should detect when an empty string is auto-assigned to such InputPorts and instead utilize the user-defined std::nullopt default value to prevent these runtime errors.

[facontidavide]

I Will look into this

[facontidavide]

Check 83fce13

If the problem persists, please tell me how to extend the unit test Default_Issues_767_768 to cover your case.

[KentaKato]

@facontidavide
Thank you for your prompt response. However, the issue still persists. I have implemented a unit test to reproduce it and submitted a pull request #773.