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Perl 5.38


A new perl 5.38 version brings a lot of changes done over a year of development. Perl 5.38 was released on July 3rd 2023. See perldelta for 5.38.0 for more details about new release.


Current status

Completed Items

  • Get dedicated build-root from rel-engs (f39-perl)
  • Upstream to release Perl 5.38
  • Define perl_bootstrap in perl-srpm-macros
  • Rebase perl to 5.38.0
  • Rebuild all dual-lived packages (83) - otherwise dnf recommends --skip-broken and fails
  • Rebuild packages needed for minimal build-root
  • Rebuild packages needed for building source packages from git repository
  • Rebuild packages requiring or versioned perl(MODULE_COMPAT): Use Fedora::Rebuild dependency solver
  • Undefine perl_bootstrap
  • Rebuild packages having perl_bootstrap condition in spec file (51 packages)
  • Rebuild all updated packages
  • Final lists of results
  • Merge dedicated build-root to rawhide and remove the dedicated one by rel-engs
  • Synchronize packages upgraded in f39 build root

Items in Progress

  • Rebuild Perl packages: 604 of 606 done (99.66 %)
  • Failed packages (2):

Items to Be Done

Detailed Description

New perl is released every year and updates containing mainly bug fixes follow during the year. The 5.38.0 version is stable release this year.

Benefit to Fedora

Up-to-date and latest perl release will be delivered to Fedora users.


Every Perl package will be rebuilt in a dedicated f39-perl build-root against perl 5.38.0 and then if no major problem emerges the packages will be merged back to f39 build-root.

  • Proposal owners: New perl and all packages requiring or versioned perl(MODULE_COMPAT) will be rebuilt into f39-perl build-root.
  • Other developers: Owners of packages that fail to rebuild, mainly perl-sig users, will be asked using Bugzilla to fix or remove their packages from the distribution.

Release engineers will be asked for new f39-perl build-root inheriting from f39 build-root. After successful finishing the rebuild, they will be asked to merge f39-perl packages back to f39 build-root.

  • 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

Vast majority of functionality will be preserved. Only the packages that failed to build against perl 5.38 will be removed from the distribution. That will require to remove those packages from the existing systems otherwise a package manager will encounter unsatisfied dependencies. The developers in Perl language are advised to install perl-doc and perl-debugger packages.

How To Test

Try upgrading from Fedora 38 to 39. Try some Perl application to verify they work as expected. Try embedded perl in slapd or snmpd.

User Experience

There should not be any remarkable change in user experience. With the exception that previously locally installed modules with a CPAN clients will need a reinstallation.


There is more than 3500 packages depending on perl. It is the first rebuild where we will rebuild only all dual-lived packages and packages which require or versioned perl(MODULE_COMPAT). It means only about 600 packages needs to rebuild. Most of them are expected not to break. Finishing this change can be endangered only by critical changes in a toolchain. noarch packages don't need to be rebuilt now.

Contingency Plan

  • Contingency mechanism: If we find perl 5.38 is not suitable for Fedora 39, we will revert back to perl 5.36 and we drop the temporary build-root with already rebuilt packages.
  • Contingency deadline: branching Fedora 39 from Rawhide.
  • Blocks release? No.


Release Notes

  • Core Enhancements
    • New class feature - new experimental syntax is now available for defining object classes, where per-instance data is stored in "field" variables that behave like lexicals.
    • Unicode 15.0 is supported
    • Deprecation warnings now have specific subcategories - it is still possible to disable all deprecation warnings in a single statement, but now is possible to have a finer grained control.
    • %{^HOOK} API introduced - this hash contains coderefs which are called when various perl keywords which are hard or impossible to wrap are called. The keys of this hash are named after the keyword that is being hooked, followed by two underbars and then a phase term; either "before" or "after".
    • New environment variable PERL_RAND_SEED which can be used to cause a perl program which uses rand without using srand() explicitly or which uses srand() with no arguments to be repeatable.
    • Defined-or and logical-or assignment default expressions in signatures
    • @INC Hook Enhancements and $INC and INCDIR
    • Forbidden control flow out of defer or finally now detected at compile-time
    • Optimistic eval in patterns - the use of (?{ ... }) and (??{ ... }) in a pattern disables various optimisations globally in that pattern. This may or may not be desired by the programmer. This release adds the (*{ ... }) equivalent. The only difference is that it does not and will never disable any optimisations in the regex engine.
    • REG_INF has been raised from 65,536 to 2,147,483,647
    • New API functions optimize_optree and finalize_optree for operating on optree fragments
    • Some gotos are now permitted in defer and finally blocks
    • New regexp variable ${^LAST_SUCCESSFUL_PATTERN} - this allows access to the last successful pattern that matched in the current scope
    • Locale category LC_NAME now supported on participating platforms
  • Incompatible Changes
    • readline() no longer clears the stream error and eof flags
    • INIT blocks no longer run after an exit() in BEGIN
    • Syntax errors will no longer produce "phantom error messages".
    • utf8::upgrade() - starting in this release, if the input string is undef, it remains undef
  • Deprecations
    • Use of ' as a package name separator is deprecated, will be removed in Perl 5.42
    • switch and smartmatch operator ~~ is deprecated, will be removed in Perl 5.42
  • Lots of modules were updated