Saxon

Thanks for reporting this, but I don't think we'll be able to fix it without a full repro - in particular, the full schema, but ideally an XPath (or XQuery etc) that shows the failure reproducibly; we'll need that to ensure that any patch actually works.

I know what the general problem area is. When a simpleType is first encountered in a schema, it's not always possible to tell immediately whether it's an atomic, list, or union type. That's because we might not yet know anything about the base type. So we provisionally allocate a SimpleTypeDefinition object, to be resolved later. By the time we come to actually use a schema, there should be no SimpleTypeDefinition objects left, they should all have been replaced by an AtomicType, ListType, or UnionType. So something has gone wrong, but we don't know what.

It's a problem that used to crop up quite frequently but we haven't seen it for many years now.

Another observation: at the point of failure, it's parsing a type declaration in a "let" clause within a FLWOR expression. I'm having trouble reconciling that with your code fragment, which looks like an XQuery function declaration in an XQuery prolog; except that you wouldn't normally have an external function declaration for a built-in (internal) function like fn:data. I don't really understand what you are doing when the failure occurs.

we are calling the built-in (internal) function fn:data(...) with the parameter "Example"in the attached simple.xsd

I would love to get to the bottom of this issue but we can't solve it without more information, so I'm closing it as unresolved.

If you are able to get us a repro, please re-open the issue.