say $-[1], ': ', $1 while 'olololo' =~ /
    (?=
        (
            (.)(?-2)\g-1 | (.).\g-1 
        )
    )
/gx;

say '*';

say 'match' if 'olololo' =~ /
    ^
    ( 
        (
            (.)(?-3)\g-1 | (.).\g-1 
        )
        (?{ 
            say $-[2], ': ', $2
        })
    )
    (?#*F)
/x;