Saxon

I have created the following test case FunctionCall-058:

         declare function local:f($callback as function(xs:integer) as xs:boolean) as xs:boolean {
             $callback(year-from-date(current-date()) div 1900)
         };
         local:f(function($d as xs:decimal) as xs:boolean { $d lt 0 })

This should fail because the $callback function requires an xs:integer but the supplied value (the result of the integer division) is an xs:decimal.

What is supposed to happen according to the spec is that the supplied function (which accepts an x:decimal) is coerced to the required type (which does not). The means that the function actually supplied to the $callback parameter is effectively:

function($d1 as xs:integer) as xs:boolean {
    function($d2 as xs:decimal) as xs:boolean { $d2 lt 0 } ($d1)
}

which should fail with a type error when called supplying an xs:decimal.

However, because the value supplied to the $callback parameter is an instance of the required type, Saxon skips the process of function coercion wrongly believing it to be unnecessary; his has the effect that the type error is not detected.