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perl5219delta - what is new for perl v5.21.9


This document describes differences between the 5.21.8 release and the 5.21.9 release.

If you are upgrading from an earlier release such as 5.21.7, first read perl5218delta, which describes differences between 5.21.7 and 5.21.8.


With this release we are now in the user-visible changes portion of the code freeze as we prepare for the next stable release of Perl 5.

Core Enhancements

qr/\b{gcb}/ is now handled in regular expressions

gcb stands for Grapheme Cluster Boundary. It is a Unicode property that finds the boundary between sequences of characters that look like a single character to a native speaker of a language. Perl has long had the ability to deal with these through the \X regular escape sequence. Now, there is an alternative way of handling these. See "\b{}, \b, \B{}, \B" in perlrebackslash for details.

qr/\b{wb}/ is now handled in regular expressions

wb stands for Word Boundary. It is a Unicode property that finds the boundary between words. This is similar to the plain \b (without braces) but is more suitable for natural language processing. It knows, for example that apostrophes can occur in the middle of words. See "\b{}, \b, \B{}, \B" in perlrebackslash for details.

qr/\b{sb}/ is now handled in regular expressions

sb stands for Sentence Boundary. It is a Unicode property to aid in parsing natural language sentences. See "\b{}, \b, \B{}, \B" in perlrebackslash for details.

New bitwise operators

A new experimental facility has been added that makes the four standard bitwise operators (& | ^ ~) treat their operands consistently as numbers, and introduces four new dotted operators (&. |. ^. ~.) that treat their operands consistently as strings. The same applies to the assignment variants (&= |= ^= &.= |.= ^.=).

To use this, enable the "bitwise" feature and disable the "experimental::bitwise" warnings category. See "Bitwise String Operators" in perlop for details. [ #123466]

no re covers more and is lexical

Previously running no re would only turn off a few things. Now it turns off all the enabled things. For example, previously, you couldn't turn off debugging, once enabled, inside the same block.

Incompatible Changes

There are no changes intentionally incompatible with 5.21.8. If any exist, they are bugs, and we request that you submit a report. See "Reporting Bugs" below.

Modules and Pragmata

Updated Modules and Pragmata


New Documentation




Changes to Existing Documentation








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 Warnings

Changes to Existing Diagnostics

Utility Changes



Configuration and Compilation



Support for new warnings categories outside of "all"

The new option for warnings outside the all category in the warnings pragma has been removed for now.

For more context, you can refer to the following discussion thread.

Platform Support

Platform-Specific Notes



Look for the Sun Studio compiler in both /opt/solstudio* and /opt/solarisstudio*.


Selected Bug Fixes


Perl 5.21.9 represents approximately 4 weeks of development since Perl 5.21.8 and contains approximately 170,000 lines of changes across 520 files from 32 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 160,000 lines of changes to 270 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.21.9:

Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, David Golden, David Mitchell, Father Chrysostomos, H.Merijn Brand, Hugo van der Sanden, James E Keenan, James Raspass, Jarkko Hietaniemi, Karen Etheridge, Karl Williamson, Kent Fredric, Lajos Veres, Leon Timmermans, Lukas Mai, Mathieu Arnold, Matthew Horsfall, Peter Martini, Petr Písař, Randy Stauner, Ricardo Signes, Sawyer X, Shlomi Fish, Sisyphus, Steve Hay, Tony Cook, Yves Orton, Ævar Arnfjörð Bjarmason.

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 articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at . There may also be information at , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.


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.