perl -MData::Dump::Streamer -le '@ary = (); x($ary[5],"foo"); sub x { $_[0] = $_[1] }; Dump(\@ary)'
$ARRAY1 = [
            ( undef ) x 5,
            'foo'
          ];
perl -MData::Dump::Streamer -le '@ary = (); x($ary[5],"foo"); sub x { $_[0] }; Dump(\@ary)'
$ARRAY1 = [];