Why "ostream_iterator" will have a warning？ [closed]

void arrayList<T>::output(ostream &out) const {

    copy(element, element + listSize, ostream_iterator<T>(cout, " "));

}

I just use this old code to print some digital, but this code always has a warning which calls "Use of function template name with no prior declaration in function call with explicit template arguments is a C++20 extension"