Add tool to generate updated module list for perldelta

diff --git a/Porting/corelist-perldelta.pl b/Porting/corelist-perldelta.pl
new file mode 100755 (executable)
index 0000000..b3aa772
--- /dev/null
+++ b/Porting/corelist-perldelta.pl
@@ -0,0 +1,28 @@
+#!perl
+use 5.010;
+use strict;
+use warnings;
+use lib 'Porting';
+use Maintainers qw/%Modules/;
+use Module::CoreList;
+
+my $corelist = \%Module::CoreList::version;
+my @versions = sort keys %$corelist;
+
+# by default, compare latest two version in CoreList;
+my ($old, $new) = @ARGV;
+$old ||= $versions[-2];
+$new ||= $versions[-1];
+
+say "=head2 Updated Modules\n";
+say "=over 4\n";
+
+for my $mod ( sort { lc $a cmp lc $b } keys %Modules ) {
+  my $old_ver = $corelist->{$old}{$mod};
+  my $new_ver = $corelist->{$new}{$mod};
+  next unless defined $old_ver && defined $new_ver && $old_ver ne $new_ver;
+  say "=item C<$mod>\n";
+  say "Upgraded from version $old_ver to $new_ver.\n";
+}
+
+say "=back\n";