Bug#747628: perl: module deprecations / removals in 5.20

[Niko Tyni]

Package: perl

As of 5.19.11, the following modules are becoming deprecated in 5.20:

cpan/CGI/lib/CGI.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Apache.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Carp.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Cookie.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Fast.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Pretty.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Push.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Switch.pm:use if $] >= 5.019, 'deprecate';
cpan/CGI/lib/CGI/Util.pm:use if $] >= 5.019, 'deprecate';
cpan/Module-Build/lib/Module/Build.pm:use if $] >= 5.019, 'deprecate';
cpan/Module-Build/lib/inc/latest.pm:use if $] >= 5.019, 'deprecate';
cpan/Module-Build/lib/inc/latest/private.pm:use if $] >= 5.019, 'deprecate';
cpan/Package-Constants/lib/Package/Constants.pm:use if $] >= 5.019006, 'deprecate';

So we need to package Package-Constants separately, and start recommending
libcgi-pm-perl, libmodule-build-perl, and libpackage-constants-perl.

Module-Build deprecation warnings are probably going to be numerous in
build logs.

I'm not quite sure how we should treat those modules that have been
removed between 5.18 and 5.20. In #702096 I wrote

> We probably need to package all of these separately. If jessie is going
> to release with Perl 5.18, adding them as recommendations to the perl
> package should be enough. If we release with something later we probably
> need real dependencies for one release cycle.

Now that we're aiming for 5.20 in jessie, do we need to bite the bullet
and add the hard dependencies? I sort of think recommendations might
be enough after all.

AIUI, the concern is that without the dependencies, users upgrading from
wheezy will have their programs silently broken by disappeared modules,
as they are skipping those upstream releases with deprecation warnings.
But why aren't recommendations adequate for that? Users that have
configured apt to ignore recommendations have explicitly indicated that
they prefer disk space savings over safety guards, IMO.

The other POV is that upstream manages module removals carefully, making
sure that users will see the warnings, and we should be as careful not
undermine that.

A full list of relevant removals is

 libarchive-extract-perl 
 libb-lint-perl
 libcpanplus-perl
 libfile-checktree-perl
 liblog-message-perl
 libmodule-pluggable-perl
 libobject-accessor-perl
 libpod-latex-perl
 libterm-ui-perl
 libtext-soundex-perl

(I note that we don't have a separate package for Version::Requirements,
 the only module that was removed in 5.18. This is as discussed in
 http://lists.alioth.debian.org/pipermail/perl-maintainers/2013-March/003495.html
)
-- 
Niko Tyni   ntyni at debian.org