use re Debug=> <qw(DUMP EXECUTE OFFSETS TRIEC);
my @tests=@(
  XY     =>  'X(A|[B]Q||C|D)Y' ,
  foobar =>  '[f][o][o][b][a][r]',
  x  =>  '.[XY].',
  'ABCD' => '(?:ABCP|ABCG|ABCE|ABCB|ABCA|ABCD)',
  'D:\dev/perl/ver/28321_/perl.exe'=>
  'm/(\.COM|\.EXE|\.BAT|\.CMD|\.VBS|\.VBE|\.JS|\.JSE|\.WSF|\.WSH|\.pyo|\.pyc|\.pyw|\.py)$/i',
  'q'=>'[q]',
);
while ((nelems @tests)) {
    my @($str,$pat)=@(splice @tests,0,2);
    print $^STDERR, "\n";
    $pat="m/$pat/" if substr($pat,0,2) ne 'm/';
    # string eval to get the free regex message in the right place.
    eval qq[
        print \$^STDERR, "$str"=~$pat ?? '\%MATCHED\%' !! '\%FAILED\%',"\n";
    ];
    die $^EVAL_ERROR if $^EVAL_ERROR;
}