You are viewing the version of this documentation from Perl 5.22.0. View the latest version



perl5213delta - what is new for perl v5.21.3


This document describes differences between the 5.21.2 release and the 5.21.3 release.

If you are upgrading from an earlier release such as 5.21.1, first read perl5212delta, which describes differences between 5.21.1 and 5.21.2.

Core Enhancements

defined(@array = LIST) is no longer fatal

In 5.21.1, defined(@array) was made fatal. This has been relaxed to not die if the argument is assigning to an array.

Floating point parsing has been improved

Parsing and printing of floating point values has been improved.

As a completely new feature, hexadecimal floating point literals (like 0x1.23p-4) are now supported, and they can be output with printf %a.


The Safe module could allow outside packages to be replaced

Critical bugfix: outside packages could be replaced. Safe has been patched to 2.38 to address this.

Incompatible Changes

use UNIVERSAL '...' is now a fatal error

Importing functions from UNIVERSAL has been deprecated since v5.12, and is now a fatal error. "use UNIVERSAL" without any arguments is still allowed.

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

New Warnings

Changes to Existing Diagnostics

Configuration and Compilation

Platform Support

Platform-Specific Notes


Build support has been improved for cross-compiling in general and for Android in particular.


c99 options have been cleaned up, hints look for solstudio as well as SUNWspro, and support for native setenv has been added.


finite, finitel, and isfinite detection has been added to, environment handling has had some minor changes, and a fix for legacy feature checking status.


%I64d is now being used instead of %lld for MinGW.

Internal Changes

Selected Bug Fixes


Perl 5.21.3 represents approximately 4 weeks of development since Perl 5.21.2 and contains approximately 21,000 lines of changes across 250 files from 25 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 18,000 lines of changes to 160 .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 5.21.3:

Aaron Crane, Abigail, Alberto Simões, Andy Dougherty, Brian Fraser, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, David Mitchell, Father Chrysostomos, H.Merijn Brand, James E Keenan, Jan Dubois, Jarkko Hietaniemi, Karen Etheridge, Karl Williamson, Lukas Mai, Peter Martini, Rafael Garcia-Suarez, syber, Tony Cook, Vladimir Marek, 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 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.