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perl52110delta - what is new for perl v5.21.10


This document describes differences between the 5.21.9 release and the 5.21.10 release.

If you are upgrading from an earlier release such as 5.21.8, first read perl5219delta, which describes differences between 5.21.8 and 5.21.9.

Incompatible Changes

(?[...]) operators now follow standard Perl precedence

This experimental feature allows set operations in regular expression patterns. Prior to this, the intersection operator had the same precedence as the other binary operators. Now it has higher precedence. This could lead to different outcomes than existing code expects (though the documentation has always noted that this change might happen, recommending fully parenthesizing the expressions). See "Extended Bracketed Character Classes" in perlrecharclass.

Performance Enhancements

Modules and Pragmata

Updated Modules and Pragmata


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 Errors


Platform Support

New Platforms

z/OS running EBCDIC Code Page 1047

Core perl now works on this EBCDIC platform. Early perls also worked, but, even though support wasn't officially withdrawn, recent perls would not compile and run well. Perl 5.20 would work, but had many bugs which have now been fixed. Many CPAN modules that ship with Perl still fail tests, including Pod::Simple. However the version of Pod::Simple currently on CPAN should work; it was fixed too late to include in Perl 5.22. Work is under way to fix many of the still-broken CPAN modules, which likely will be installed on CPAN when completed, so that you may not have to wait until Perl 5.24 to get a working version.

Platform-Specific Notes


The archname now distinguishes use64bitint from use64bitall.

Internal Changes

Selected Bug Fixes

Known Problems


Perl 5.21.10 represents approximately 4 weeks of development since Perl 5.21.9 and contains approximately 170,000 lines of changes across 860 files from 27 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 170,000 lines of changes to 610 .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 5.21.10:

Chris 'BinGOs' Williams, David Golden, David Mitchell, David Wheeler, Father Chrysostomos, H.Merijn Brand, Hugo van der Sanden, James E Keenan, Jarkko Hietaniemi, Jasmine Ngan, Jerry D. Hedden, John Goodyear, Karen Etheridge, Karl Williamson, Lukas Mai, Matthew Horsfall, Nicholas Clark, Petr Písař, Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Sawyer X, Steffen Müller, Steve Hay, Sullivan Beck, Tony Cook, Vincent Pit.

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.