MDEV-22744 *SAN: sql/item_xmlfunc.cc:791:43: runtime error: downcast of...

MDEV-22744 *SAN: sql/item_xmlfunc.cc:791:43: runtime error: downcast of address ... which does not point to an object of type 'Item_func' note: object is of type 'Item_bool' (on optimized builds)

In Item_nodeset_func_predicate::val_nodeset, args[1] is not necessarily
an Item_func descendant. It can be Item_bool.

Removing a wrong cast. It was not really needed anyway.

sql/item_xmlfunc.cc

@@ -797,7 +797,6 @@ String *Item_nodeset_func_attributebyname::val_nodeset(String *nodeset)
 String *Item_nodeset_func_predicate::val_nodeset(String *str)
 {
   Item_nodeset_func *nodeset_func= (Item_nodeset_func*) args[0];
-  Item_func *comp_func= (Item_func*)args[1];
   uint pos= 0, size;
   prepare(str);
   size= fltend - fltbeg;
@@ -807,7 +806,7 @@ String *Item_nodeset_func_predicate::val_nodeset(String *str)
     ((XPathFilter*)(&nodeset_func->context_cache))->append_element(flt->num,
                                                                    flt->pos,
                                                                    size);
-    if (comp_func->val_int())
+    if (args[1]->val_int())
       ((XPathFilter*)str)->append_element(flt->num, pos++);
   }
   return str;