This should now be handled in various visitors. Three cases come to my mind: First,treetransform.py this is needed so that this error will not re-appear in a test case like this

T=TypeVar("T",int,str)deffoo(x:T)->T:A=type[int]|strreturnx

Second,aststrip.py, be sure that when you switch imported names from types to variables, you do get an error about missing__or__ on update. Third,semanal_typeargs.py (usesMixedTraverserVisitor), since we should not carry malformed instances around (with number of type args), they may cause crashes, add a test just in case with a malformed instance in| alias.

And in general adding in to the basicTraverserVisitor is a good idea. Maybe just grep fordef visit_index_expr( and see where we useanalyzed.

Very good points! I'll fix these.