Rebuild old Perl Modules

To rebuild the perl libraries from AUR for pacmanager I use yaourt:

yaourt -S --asdeps perl-gnome2-gconf glade-perl perl-crypt-blowfish perl-gnome2-vte perl-expect perl-crypt-rijndael perl-gtk2-ex-simple-list perl-io-stty perl-io-tty perl-net-arp perl-yaml perl-crypt-cbc perl-gtk2-unique perl-socket6 uuid

so just replace the libraries with the ones pacman gave you:

yaourt -S --asdeps gscan2pdf perl-filesys-df perl-config-general perl-data-uuid perl-goo-canvas perl-gtk2-ex-simple-list perl-gtk2-imageview perl-pdf-api2 perl-sane perl-set-intspan

Update 2018 additional

the perl 5.28 update in Arch means that you have to rebuild all unsupported packages again. The solution to fix dependency errors is to remove the offending AUR perl application & then remove the orphan perl libraries & update your system:

sudo pacman -Rns $(pacman -Qtdq)
sudo pacman -Syu

Finally reinstall the AUR perl application.

Update 2019 additional

With the perl 5.30.0 update pacman now gives warnings about old perl libs. This time I had a big update & needed to do the following:

sudo pacman -R $conflicting_perl_mod_&_app
sudo pacman -Syu
# pacman now generates a warning for unused perl libs
pacman -R $(pacman -Qqo '/usr/lib/perl5/5.28')
pacman -S $perl_app
# optional remove orphaned packages
sudo pacman -Rns $(pacman -Qtdq)
sudo pacman -Syu

Adding onto Stuart Cardall's answer, make a .sh script to rebuild the listed perl modules, then you can just run that whenever you update perl and get that warning:

yaourt -S --asdeps --noconfirm $(pacman -Qqo '/usr/lib/perl5/vendor_perl')
yaourt -S --asdeps --noconfirm $(pacman -Qqo '/usr/lib/perl5/site_perl')