You are viewing the version of this documentation from Perl 5.39.2. This is a development version of Perl.



perldelta - what is new for perl v5.39.2


This document describes differences between the 5.39.1 release and the 5.39.2 release.

If you are upgrading from an earlier release such as 5.39.0, first read perl5391delta, which describes differences between 5.39.0 and 5.39.1.

Core Enhancements

New __CLASS__ Keyword

When using the new class feature, code inside a method, ADJUST block or field initializer expression is now permitted to use the new __CLASS__ keyword. This yields a class name, similar to __PACKAGE__, but whereas that gives the compile-time package that the code appears in, the __CLASS__ keyword is aware of the actual run-time class that the object instance is a member of. This makes it useful for method dispatch on that class, especially during constructors, where access to $self is not permitted.

For more information, see "__CLASS__" in perlfunc.

Modules and Pragmata

Updated Modules and Pragmata


The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see perldiag.

New Diagnostics

New Errors

New Warnings

Configuration and Compilation


Tests were added and changed to reflect the other additions and changes in this release.

Platform Support

Platform-Specific Notes

Serenity OS

Out of the box support for Serenity OS was added.


Workaround a bug in most 32-bit Mingw builds, where the generated code, including the code in the gcc support library, assumes 16-byte stack alignment, which 32-bit Windows does not preserve. [GH #21313]

Internal Changes

Selected Bug Fixes


Perl 5.39.2 represents approximately 4 weeks of development since Perl 5.39.1 and contains approximately 38,000 lines of changes across 510 files from 24 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 27,000 lines of changes to 370 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.39.2:

Beckett Normington, Dagfinn Ilmari Mannsåker, David Golden, David Mitchell, Elvin Aslanov, Erik Huelsmann, Greg Kennedy, H.Merijn Brand, James E Keenan, James Raspass, Karen Etheridge, Karl Williamson, Leon Timmermans, Lukas Mai, Nicolas Mendoza, Nicolas R, OpossumPetya, Paul Evans, Raul E Rangel, Ricardo Signes, Richard Leach, Steve Hay, Tony Cook, Yves Orton.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the perl bug database at There may also be information at, the Perl Home Page.

If you believe you have an unreported bug, please open an issue at Be sure to trim your bug down to a tiny but sufficient test case.

If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.

Give Thanks

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the perlthanks program:


This will send an email to the Perl 5 Porters list with your show of thanks.


The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.