I don't have any problem running the example I posted in Perl 5.10:

#!/usr/bin/perl

use strict;
use warnings;
use Parse::RecDescent;

my $p2 = Parse::RecDescent->new(q(
                                hyphen     : "-"
                                option     : "a" | "b" | "c"
                                Format     : Entry(s)
                                Pre        : hyphen option
                                Post       : option hyphen
                                Entry      : Pre | Post
                                { use Data::Dumper; print Dumper \%ite
+m;}
));
$p2->Format('a-');
$p2->Format('-a');
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output:

$VAR1 = {
          'Post' => '-',
          '__RULE__' => 'Entry'
        };
[download]