Changes/Perl replace MODULE COMPAT by generator

Perl: Replace versioned MODULE_COMPAT_ requires by RPM dependency generator

Summary

A perl(:MODULE_COMPAT_%(eval "`%{__perl} -V:version`"; echo $version)) run-time dependency will be removed from all Perl spec files. The replacement will be generated by dependency generator which will be placed in perl-generators.

The result of generator will be based on content of the binary packages. That will significantly shrink an amount of Perl packages required to be rebuilt with each Perl upgrade.

Owner

• Name: Jitka Plesnikova
• Email: <jplesnik@redhat.com>

Current status

• Targeted release: Fedora Linux 38
• Last updated: 2023-02-01
• devel thread
• FESCo issue: #2898
• Tracker bug: #2158233
• Release notes tracker: #943

Completed items

• Add the file /usr/lib/rpm/fileattrs/perlcompat.attr to perl-generators in F38
• Add the file /usr/lib/rpm/fileattrs/perlcompat.attr to perl-generators in F37
• Add the file /usr/lib/rpm/fileattrs/perlcompat.attr to perl-generators in F36
• Update Fedora Packaging Guidelines for Perl
• Remove perl(:MODULE_COMPAT_XXX) from run-time in all F38 spec files (3259)
• Create the package perl-generators-epel which provides the functionality for EPEL 7/8/9
• Add perl-generators-epel to epel-rpm-macros (EPEL7, EPEL8, EPEL9)

Items in progress

• Update fedora-review to not check perl(MODULE_COMPAT_XXX) in spec files (BZ#2161280)

Detailed Description

The list of packages that need to be rebuilt with the new major version of Perl is determined according to the dependency on perl(:MODULE_COMPAT_XXX) now.

In Fedora, all Perl modules run-require the versioned perl(:MODULE_COMPAT_XXX) provided by perl-libs now.

However, only packages with compiled code need to have a dependency on the particular version of Perl it was built against, or on a newer version of Perl that provides backward compatibility with it. For those packages, we need to ensure that the packages will use the right version of libperl.so for the Perl used during the rebuild.

The other packages don't need to be rebuilt against each new major version of Perl, they only have to require non-versioned perl-libs which includes all directories used by all Perl modules.

The new generator will generate runtime requirements based on files which are in the package.

The content of /usr/lib/rpm/fileattrs/perlcompat.attr will be:

%__perlcompat_requires() %{lua:
   if macros[1]:match('.+%.so$') and macros.perl_version then
      print('perl(:MODULE_COMPAT_' .. macros.perl_version .. ')')
   else
      print('perl-libs')
   end
}
%__perlcompat_path ^(%{perl_vendorarch}|%{perl_vendorlib}|%{perl_privlib}|%{perl_archlib})/.+

The file will be placed in perl-generators which requires perl-macros. Since RPM 4.15, perl-macros provides definition of perl_vendor*, perl_privlib and perl_archlib and it requires perl-interpreter. The Fedora guidelines already require Perl modules to BuildRequire perl-generators.

The generator will evaluate to the correct value. There is a known, yet harmless, imperfection: The generator will evaluate to perl-libs for each package which contains any (non *.so) file in the given paths. It means the packages with compiled code will usually require both perl(:MODULE_COMPAT_<perl_version>) and perl-libs.

This generator will work for all supported Fedoras.

I'll add perl-generators-epel which provides the similar behavior for EPEL 7/8/9.

Benefit to Fedora

It will simplify the rebuild and reduce the number of packages which have to be rebuild from 3259 to approximately 600. It should currently be enough to rebuild only multi-arch packages and those that are part of the Perl itself (dual-life packages). Here we need to ensure that the packages will use the right libperl.so for the Perl used. The generator approach will also be shorter and clearer for packagers.

Scope

• Proposal owners:
  • Submit Fedora Packaging Guidelines for Perl update to Fedora Packaging Committee.
  • Update and rebuild perl-generators source package.
  • Add /usr/lib/rpm/fileattrs/perlcompat.attr to perl-generators package in older Fedoras.
  • Remove Requires perl(:MODULE_COMPAT_XXX) in all spec files.

• Other developers: Get familiar with new Fedora Packaging Guidelines for Perl.

• Release engineering: No action needed. #Releng issue number

• Policies and guidelines: N/A (not needed for this Change)

• Trademark approval: N/A (not needed for this Change)

• Alignment with Objectives:

Upgrade/compatibility impact

N/A

How To Test

All packages with compiled code should run-require perl(:MODULE_COMPAT_%{perl_version}) and probably also perl-libs - it is explaned in Detailed Description. The other packages should run-require perl-libs only.

User Experience

There should not be any remarkable change in user experience.

Dependencies

This change will affect 3259 source packages and all binary noarch packages. The rebuild of affected packages will be done by mass rebuild of Fedora 38. There is no dependency on other Fedora changes.

Contingency Plan

• Contingency mechanism: The change will be reverted.
• Contingency deadline: Before Mass Rebuild.
• Blocks release? No.