"instance of document-node(element(x))" in predicate

[Chris Hillery]

This is W3C test test/rbkt/w3c_testsuite/XQuery/PathExpr/Steps/Steps-leading-lone-slash-8a , which is:

  declare variable $var := document {<a>123</a>};
  $var[(/) instance of document-node(element(x))]

This returns <a>123</a>, but according to the W3C should return empty sequence. If you replace the "(/)" with just ".", you get the same result; but if you change $var to be an element instead of a document, you get the empty sequence. It seems as though perhaps the element(x) portion of the predicate is not being evaluated.

Assigned to Nicolae for the moment; re-assign as necessary.

(Note: This is a W3C failure that we were not previously detecting due to a testdriver bug, so it will appear as a regression in our conformance results.)