use strict;
  use Test::More 'no_plan';

  my $string  = "Subject: Hello Jimbo Johnson\x0ADate: whatever";
  like($string, '/(?m:^Subject: Hello Jimbo Johnson$)/', "q{//}",);
  like($string, qr{(?m:^Subject: Hello Jimbo Johnson$)}, "qr{(?m:...)}",);
  like($string, qr{^Subject: Hello Jimbo Johnson$}m,     "qr{}m",);

  my $re_no_m = qr{^Subject: Hello Jimbo Johnson$};  # no /mg
  ok($string !~ m{$re_no_m}m, "should not match m{}m");