Saxon

We have an XPath expression containing an attribute predicate of the form:

[@foo = 3].

The 'foo' attribute in question has a named union type which is the union of xs:integer and an anonymous restriction of xs:string to a single enumerated value.

When the value of the attribute is the allowed string value we expect a type error from evaluation of the predicate but generating the error is giving an NPE from the type's toString in Saxon 9.7 (it was successful in Saxon 9.6).

The stack trace is:

java.lang.NullPointerException

at com.saxonica.ee.schema.UserAtomicType.toString(UserAtomicType.java:490)

at net.sf.saxon.type.Type.displayTypeName(Type.java:256)

at net.sf.saxon.expr.ValueComparison.compare(ValueComparison.java:720)

at net.sf.saxon.expr.GeneralComparison.compare(GeneralComparison.java:820)

at net.sf.saxon.expr.GeneralComparison.evaluateManyToOne(GeneralComparison.java:676)

at net.sf.saxon.expr.GeneralComparison.effectiveBooleanValue(GeneralComparison.java:625)

at net.sf.saxon.expr.FilterIterator$NonNumeric.matches(FilterIterator.java:198)

at net.sf.saxon.expr.FilterIterator.getNextMatchingItem(FilterIterator.java:81)

at net.sf.saxon.expr.FilterIterator.next(FilterIterator.java:64)

at net.sf.saxon.tree.iter.AtomizingIterator.next(AtomizingIterator.java:54)

at net.sf.saxon.tree.iter.AtomizingIterator.next(AtomizingIterator.java:27)

at com.saxonica.ee.optim.GeneralComparisonEE.effectiveBooleanValue(GeneralComparisonEE.java:113)

at net.sf.saxon.sxpath.XPathExpression.effectiveBooleanValue(XPathExpression.java:229)

at net.sf.saxon.s9api.XPathSelector.effectiveBooleanValue(XPathSelector.java:232)

... (non-Saxon code)