resolve ${x} names to corresponding XML path reference in custom settings attributes

[tiritea]

Software and hardware versions

all

Problem description

Unlike custom instance, binding or body attributes, specifying a ${x} style question reference for custom settings attributes is not resolved to the corresponding XML path reference.

Steps to reproduce the problem

Create a new XLSForm and add a custom attribute - eg attribute::xyz - to the settings page, as described here: https://xlsform.org/en/#advanced-use-and-extensibility

For the value of the custom attribute, put a ${x} style reference to one of the questions in your form, eg "${name}"

After passing the form thru pyxform, the resulting attribute that is added to the root element in the resulting XML form is just an unmodified copy of this string; eg

<data customSettingsAttribute2="${name}" ...>
...
</data>

Expected behavior

The desired/expected behavior is that this ${name} reference would be resolved to the corresponding XML path for the element; eg

<data customSettingsAttribute2="/data/name" ...>
...
</data>

much as occurs already for custom instance, binding or body attributes.

Other information

There is an extensive discussion of this issue, with examples, on the ODK Forum here: https://forum.getodk.org/t/xlsform-spec-also-resolve-foo-names-in-custom-settings-attributes/48735