You are viewing the version of this documentation from Perl 5.34.0-RC1. This is a development release of Perl.



perldelta - what is new for perl v5.34.0


This document describes differences between the 5.32.0 release and the 5.34.0 release.

If you are upgrading from an earlier release such as 5.30.0, first read perl5320delta, which describes differences between 5.30.0 and 5.32.0.

Core Enhancements

Experimental Try/Catch Syntax

An initial experimental attempt at providing try/catch notation has been added.

use feature 'try';

try {
catch ($e) {
    warn "An error occurred: $e";

For more information, see "Try Catch Exception Handling" in perlsyn.

qr/{,n}/ is now accepted

An empty lower bound is now accepted for regular expression quantifiers, like {,3}.

Blanks freely allowed within but adjacent to curly braces

(in double-quotish contexts and regular expression patterns)

This means you can write things like \x{ FFFC } if you like. This applies to all such constructs, namely \b{}, \g{}, \k{}, \N{}, \o{}, and \x{}; as well as the regular expression quantifier {m,n}. \p{} and \P{} retain their already-existing, even looser, rules mandated by the Unicode standard (see "Properties accessible through \p{} and \P{}" in perluniprops).

This ability is in effect regardless of the presence of the /x regular expression pattern modifier.

Additionally, the comma in a regular expression braced quantifier may have blanks (tabs or spaces) before and/or after the comma, like qr/a{ 5, 7 }/.

New octal syntax 0oddddd

It is now possible to specify octal literals with 0o prefixes, as in 0o123_456, parallel to the existing construct to specify hexadecimal literal 0xddddd and binary literal 0bddddd. Also, the builtin oct() function now accepts this new syntax.

See "Scalar value constructors" in perldata and "oct EXPR" in perlfunc.

Performance Enhancements

Modules and Pragmata

New Modules and Pragmata

Updated Modules and Pragmata


New Documentation

perldocstyle has been added to pod/.

This document is a guide for the authorship and maintenance of the documentation that ships with Perl.


This document describes the goals, scope, system, and rules for Perl's new governance model.

Other pod files, most notably perlpolicy, were amended to reflect its adoption.

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

New Warnings

Changes to Existing Diagnostics

Utility Changes (the debugger)

Configuration and Compilation


Tests were added and changed to reflect the other additions and changes in this release. Furthermore, these significant changes were made:

Platform Support

New Platforms


Allow building Perl on i386 9front systems (fork of plan9).

Updated Platforms


Improve support for Plan9 on i386 platforms.

MacOS (Darwin)

The hints file for darwin has been updated to handle future MacOS versions beyond 10. GH #17946

Discontinued Platforms


Support code relating to Symbian has been removed. Symbian was an operating system for mobile devices. The port was last updated in July 2009, and the platform itself in October 2012.

Platform-Specific Notes


Tests were updated to workaround DragonFlyBSD bugs in tc*() functions and ctime updates.

Mac OS X

A number of system libraries no longer exist as actual files on Big Sur, even though dlopen will pretend they do, so now we fall back to dlopen if a library file can not be found. [GH #18407]


Reading non-ASCII characters from the console when its codepage was set to 65001 (UTF-8) was broken due to a bug in Windows. A workaround for this problem has been implemented. [GH #18701]

Building with compilers (version 3.4.5 or later) using mingw runtime versions < 3.22 now works again. This was broken in Perl 5.31.4.

Building with compilers (version 3.4.5 or later) using mingw runtime versions >= 3.21 now works (for compilers up to version 5.3.0)., and thus support for dmake, has been removed. It is still possible to build Perl on Windows using nmake (Makefile) and GNU make (GNUmakefile). [GH #18511]

perl can now be built with USE_QUADMATH on MS Windows using (32-bit and 64-bit) mingw-w64 ports of gcc. [GH #18465]

The utility now needs to use ExtUtils::PL2Bat. This could cause failures in parallel builds.

Windows now supports symlink() and readlink(), and lstat() is no longer an alias for stat(). [GH #18005].

Unlike POSIX systems, creating a symbolic link on Windows requires either elevated privileges or Windows 10 1703 or later with Developer Mode enabled.

stat(), including stat FILEHANDLE, and lstat() now uses our own implementation that populates the device dev and inode numbers ino returned rather than always returning zero. The number of links nlink field is now always populated.

${^WIN32_SLOPPY_STAT} previously controlled whether the nlink field was populated requiring a separate Windows API call to fetch, since nlink and the other information required for stat() is now retrieved in a single API call.

The -r and -w operators now return true for the STDIN, STDOUT and STDERR handles. Unfortunately it still won't return true for duplicates of those handles. [GH #8502].

The times returned by stat() and lstat() are no longer incorrect across Daylight Savings Time adjustments. [GH #6080].

-x on a filehandle should now match -x on the corresponding filename on Vista or later. [GH #4145].

-e '"' no longer incorrectly returns true. [GH #12431].

The same manifest is now used for Visual C++ and gcc builds.

Previously, MSVC builds were using the /manifestdependency flag instead of embedding perlexe.manifest, which caused issues such as GetVersionEx() returning the wrong version number on Windows 10.


The locale categories LC_SYNTAX and LC_TOD are now recognized. Perl doesn't do anything with these, except it now allows you to specify them. They are included in LC_ALL.

Internal Changes

Selected Bug Fixes

Known Problems


Errata From Previous Releases



Kent Fredric (KENTNL) passed away in February 2021. A native of New Zealand and a self-described "huge geek," Kent was the author or maintainer of 178 CPAN distributions, the Perl maintainer for the Gentoo Linux distribution and a contributor to the Perl core distribution. He is mourned by his family, friends and open source software communities worldwide.


Perl 5.34.0 represents approximately 10 months of development since Perl 5.32.0 and contains approximately 280,000 lines of changes across 2,100 files from 77 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 150,000 lines of changes to 1,300 .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 5.34.0:

Aaron Crane, Adam Hartley, Andy Dougherty, Ben Cornett, Branislav Zahradník, brian d foy, Chris 'BinGOs' Williams, Christian Walde (Mithaldu), Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Book, Daniel Böhmer, Daniel Laügt, Dan Kogai, David Cantrell, David Mitchell, Dominic Hamon, E. Choroba, Ed J, Eric Herman, Eric Lindblad, Eugene Alvin Villar, Felipe Gasper, Giovanni Tataranni, Graham Knop, Graham Ollis, Hauke D, H.Merijn Brand, Hugo van der Sanden, Ichinose Shogo, Ivan Baidakou, Jae Bradley, James E Keenan, Jason McIntosh, jkahrman, John Karr, John Lightsey, Kang-min Liu, Karen Etheridge, Karl Williamson, Keith Thompson, Leon Timmermans, Marc Reisner, Marcus Holland-Moritz, Max Maischein, Michael G Schwern, Nicholas Clark, Nicolas R., Paul Evans, Petr Písař, raiph, Renee Baecker, Ricardo Signes, Richard Leach, Romano, Ryan Voots, Samanta Navarro, Samuel Thibault, Sawyer X, Scott Baker, Sergey Poznyakoff, Sevan Janiyan, Shlomi Fish, Sisyphus, Sizhe Zhao, Steve Hay, TAKAI Kousuke, Thibault Duponchelle, Todd Rinaldo, Tomasz Konojacki, Tom Hukins, Tom Stellard, Tony Cook, vividsnow, Yves Orton, Zakariyya Mughal, Михаил Козачков.

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.