Whenever the "base" field of a "Param" is set, if "base" is strictly greater than the "level" field, we know the "Param" refers to a nested variable. We also know that its "base" will have to be updated when the "base" scope is exited. We can therefore add the "Param" to a list linked to the "base" scope.
Whenever a scope is exited, first check whether any "Param"s were added to its list. If yes, the "base" fields of these are updated (if the "Param"s are still named references). Then call a "scanendscope" that doesn't do anything special for named references. Or do it in the opposite order?
This assumes that "Params" are only ever freed by "scanendscope". If that's not the case, things get more complicated as one would also sometimes have to remove "Param"s from the scope lists.
I could try to prepare a patch that implements this but I would first need advice on the preferred way to implement the lists of "Param"s (linked list, new "Param" field, ...) and where/how to store them (global array, under special names in the parameter table, ...).
As a reminder, this would fix "ref2" in
this test such that the output for "ref3" is the same as the one for "ref1".
Philippe