Hi,
I'm Shuxin. Recently I came across this test case in which BaseX returned an incorrect result. Currently I could not confirm it as a bug and is only a corner case which might not be of importance, but there are some interesting behaviors which I'm also curious about.
Give XML document
<A1 id="1"><B1 id="2"></B1><B1 id="3"></B1></A1>
and XPath query
//A1[((count(./*) idiv 3) * -1763118392 * 2144097893) != 1]
BaseX return empty result set while node A1 should be returned. This should be related to overflow since making either number smaller BaseX will then return correct result and therefore could be considered not a bug. But interestingly, this only occurs when the operand given after idiv (in this case 3) is greater than 2, which result is 0. If changed to (count(./*) idiv 2) or (count(./*) idiv 1), the operand is larger but correct results are still returned. Simply substituting the whole (count(./*) idiv 3) to constant either 0, 1, 2 all returns correct results. This indicates that BaseX should have the ability of handling this expression, but is somehow affected. The version of BaseX I produced this on is the latest development commit e607ecc.
Still, this is just a corner case which might not require a fix. I submit this report just for your reference. Thank you very much!
Best Regards, Shuxin Li 2023.4.5