You are viewing the version of this documentation from Perl 5.39.4. This is a development version of Perl.



perldelta - what is new for perl v5.39.4


This document describes differences between the 5.39.3 release and the 5.39.4 release.

If you are upgrading from an earlier release such as 5.39.2, first read perl5393delta, which describes differences between 5.39.2 and 5.39.3.

Modules and Pragmata

New Modules and Pragmata

Updated Modules and Pragmata


Changes to Existing Documentation

We have attempted to update the documentation to reflect the changes listed in this document. If you find any we have missed, open an issue at

Additionally, the following selected changes have been made:




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


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

Platform Support

Platform-Specific Notes


Fixed the configure "installation prefix" prompt to accept a string rather than yes/no.

Fixed compilation by defining proper value for perl_lc_all_category_positions_init.

Increased buffer size when reading config_H.SH to fix compilation under clang.

Internal Changes

Selected Bug Fixes


Perl 5.39.4 represents approximately 5 weeks of development since Perl 5.39.3 and contains approximately 46,000 lines of changes across 460 files from 20 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 44,000 lines of changes to 390 .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 5.39.4:

Abe Timmerman, Amory Meltzer, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Jacobson, Elvin Aslanov, Gianni Ceccarelli, Graham Knop, Jake Hamby, James E Keenan, Joe McMahon, Karl Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Paul Evans, Peter John Acklam, Tony Cook, William Lyu, 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.