[basex-talk] tail recursion issue in 9.4.3

Hello,

I have encountered a difference in behaviour between versions 9.3.3 and 9.4.3 for a certain query involving tail recursion. In 9.3.3 the compiled query plan correctly applied tail call optimization. But in 9.4.3 tail call optimization is not applied, resulting in a stack overflow during execution.

Here is a minimal query that demonstrates the issue:

declare function local:f($n, $xs) { if ($n = 0) then $xs else let $x := copy $node := <a/> modify ( rename node $node as 'x') return $node return local:f($n - 1, ($xs, $x)) }; local:f(2000, ())

Mark