Description:
------------
Hi All,
   Firstly, this covers ground in <a href="http://bugs.php.net/bug.php?id=35028">bug #35028</a> and is related, but more specific. 

php 5.1.1 appears to interpret standard empty objects as "true" (as did 5.0.x). 
Unlike 5.0.x (and StdClass() in 5.1.1) empty objects returned from the simpleXML parser in 5.1.1 appear to be evaluated as "false" when queried in an if() statement.  

I know we should all be using isset(), but not all programmers play by these rules, and code which was made based on 5.0.x's way of doing it doesn't work. If I try and include this code in my app, it breaks. It could be argued that this logic is counter intuitive.

Reproduce code:
---------------
function runTest($object){
  if($object) { 
    echo "php 5.1.1 evaluates object as true\n";
  } else {
    echo "php 5.1.1 evaluates object as false\n";
  }
  var_dump($object);
}

$object0 = new StdClass();
$object1 = simplexml_load_string('<foo attr="value">bar</foo>');
$object2 = simplexml_load_string('<foo attr="value"></foo>');
$object3 = simplexml_load_string('<foo attr="value" />');

runTest($object0);
runTest($object1);
runTest($object2);
runTest($object3);


Expected result:
----------------
php 5.1.1 evaluates object as true
object(stdClass)#1 (0) {
}

php 5.1.1 evaluates object as true
object(SimpleXMLElement)#2 (1) {
  [0]=>
  string(3) "bar"
}

php 5.1.1 evaluates object as true
object(SimpleXMLElement)#2 (0) {
}

php 5.1.1 evaluates object as true
object(SimpleXMLElement)#2 (0) {
}

Actual result:
--------------
php 5.1.1 evaluates object as true
object(stdClass)#1 (0) {
}

php 5.1.1 evaluates object as true
object(SimpleXMLElement)#2 (1) {
  [0]=>
  string(3) "bar"
}

php 5.1.1 evaluates object as false
object(SimpleXMLElement)#2 (0) {
}

php 5.1.1 evaluates object as false
object(SimpleXMLElement)#2 (0) {
}