use 5.020;
use Data::Dumper;
my $tmp = qr/re/;

my @positive = grep {/$tmp/} 'rerere', 'foo';
my @negative = grep {/(?!$tmp)/} 'rerere', 'foo';

say Dumper \@positive; # 'rerere'
say Dumper \@negative; # 'rerere', 'foo'