Bug 11815

// #1: // An empty node value causes the substring() function to return true when it should return false. var strXML = '<data><record id="-a-"></record><record id="a-a">-hi-</record></data>'; var doc = (new DOMParser()).parseFromString(strXML, "text/xml"); var xpe = new XPathEvaluator(); var objResult = xpe.evaluate("//record[substring(.,1,1)='-']", doc, null, 0, null); var itm = null; var objNodes = []; while (itm = objResult.iterateNext()) objNodes.push(itm); assertEquals(1, objNodes.length); // Safari yields 2

// #2 // function name() does not work with attribute nodes var strXML = '<data><record id="-a-" a="v">???</record><record id="a-a">{abc}</record></data>'; var doc = (new DOMParser()).parseFromString(strXML, "text/xml"); var xpe = new XPathEvaluator(); var objResult = xpe.evaluate("//@*[name()='id']", doc, null, 0, null); var itm = null; var objNodes = []; while (itm = objResult.iterateNext()) objNodes.push(itm); assertEquals(2, objNodes.length); // Safari yields 0

I split this out in to two different issues. #2 is moved to bug 12340.

This appears to be a general problem in our XPath code - all C++ string literals are treated as boolean values. Easy to fix by adding another constructor to XPath::Value, but I cannot understand how this occurs; suspecting a gcc bug. Please tell me I'm wrong :-). Test case: ----------------------- #include <stdio.h> class String { public: String(const char*) {} }; class Value { public: Value(bool) { printf("bool\n"); } Value(const String&) { printf("String\n"); } }; int main() { Value val(""); } -----------------------

(In reply to comment #4) > This appears to be a general problem in our XPath code - all C++ string > literals are treated as boolean values. > > Easy to fix by adding another constructor to XPath::Value, but I cannot > understand how this occurs; suspecting a gcc bug. Please tell me I'm wrong :-). I believe this Google Groups thread answers it: http://groups.google.com/group/comp.lang.c++/browse_thread/thread/73ab483d2ef241c/487423eb73ee10d6%23487423eb73ee10d6

The replies in this thread point out that pointers can be converted to bool - but a string literal is not a pointer, it's "const char[n]" (with a deprecated conversion allowing it to be converted to char*). OTOH, the two transformations needed to get from a string literal to a bool fall into different categories (lvalue transformation and conversion), and are thus allowed in a standard conversion sequence, see section 13.3.3.1 of the standard. Not that I can claim complete understanding now, but I'm convinced.

Created attachment 12721 [details] proposed fix

Comment on attachment 12721 [details] proposed fix r=me

Committed revision 19225.