It's not a bug in Perl but a bug in your expectations. The empty RE // always matches, see perlre resp. perlop. And the first match has nothing to do with it, as removing it still produces all matches:

#!/usr/bin/perl

my @strings = ('testing','','testing','testing');

foreach my $string (@strings) {
    my $q = $string;
    my $test = 'testing';
    warn "$test =~ /$q/?";
    warn $test =~ /\Q$q\E/;
}

__END__
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ //? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.

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Update: Actually, while my reply is not untrue, the real cause is told by Anonymous Monk below. The empty match will repeat the last match.

In reply to Re: Perl bug or feature? by Corion
in thread Perl bug or feature? by yegg

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