I believe that these two tests (in prod-FunctionCall) can legitimately fail with a type error.

The first test contains the function:

declare function local:index-of($seq as xs:integer*, $item as xs:integer?) as xs:float* { 
        if (empty($item)) 
            then "item was empty" 
            else for $x at $p in $seq return if ($x eq $item) then $p else () 
        };

My interpretation of the rules for optimistic static type checking is that evaluation of the expression "item was empty" would necessarily raise a type error, and therefore the processor is allowed to raise the type error statically. (I concede that other readings of this rule are possible...)

Since the "then" branch is irrelevant to the purpose of the test, I suggest changing it to something like "then -1".

Similar reasoning applies to cbcl-promotion-004.