XPathEvaluator.evaluate() can miss errors with //

Found using the SimpleXPathAPI sample in XalanC (the last stable one, Xalan-
C_1_2-win32.zip from 17-Aug-2001 12:42), on Windows 2000, using VC6 SP5 to
compile.

With a context /

It accepts the following expressions
count(//)
count(//@*)
count(//@*|//)

but throws an exception on
count(//|//@*)

Have verified that the excpetion is being thrown by the call to
// OK, let's evaluate the expression...
const XObjectPtr theResult(
theEvaluator.evaluate(
theDOMSupport,
theContextNode,
XalanDOMString(argv[3]).c_str(),
0));
(from main() in SimpleXPathAPI.cpp)

and have traced it back inside XPathEvaluator::evaluate() where the exception
gets thrown out of
theProcessor.initXPath(
theXPath,
XalanDOMString(xpathString),
prefixResolver);
(in XPathEvaluator.cpp)

Haven't traced any further back yet.