****** str=<AB>
--- re=<(?^u:..)>
matched
no captures
--- re=<(?^u:(.)(.))>
matched
with captures <A B>
--- re=<XY>
no match
no captures
--- re=<(X)Y>
no match
no captures
--- re=<>
matched
no captures
****** str=<>
--- re=<(?^u:..)>
no match
no captures
--- re=<(?^u:(.)(.))>
no match
no captures
--- re=<XY>
no match
no captures
--- re=<(X)Y>
no match
no captures
--- re=<>
matched
no captures