While it's improved, it would be nice to give users a list of valid options for $target expressions. For example, if a nonexistent variable is referenced ($foo), we could list the variables that *are* available. If a nonexistent field ($foo->field) is given, similarly we could list the valid ones. Etc. This would supplant the (uninstalled) loc2c-test widget.
I've added code to src/tapsets.cxx to: - list variables that exist when a non-existent target variable is accessed - list structure members that exist when a non-existent structure member is accessesd
For the first case, does the variable lister also add in the globalish variables reachable from parent scopes? It may need to traverse the die's upward in a similar way as find_variable_and_frame_base().