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perl51310delta - what is new for perl v5.13.10


This document describes differences between the 5.13.9 release and the 5.13.10 release.

If you are upgrading from an earlier release such as 5.13.8, first read perl5139delta, which describes differences between 5.13.8 and 5.13.9.

Core Enhancements

The new regular expression modifiers available in suffix form

Various releases of the 5.13.x series have added new regular expression modifiers, /a, /d, /l, and /u. They were only available in infix form (e.g., (?a:...)) until this release; now they are usable in suffix form. This change was made too late to change all the affected documentation, so there are a number of places that erroneously say these must be used in infix form.

However, there is an ambiguity with the construct, s/foo/bar/le.... Due to backward compatibility constraints, in Perl 5.14 only, it will be resolved as s/foo/bar/ le..., that is, as meaning to take the result of the substitution, and see if it is stringwise less-than-or-equal-to what follows. In Perl 5.16 and later, it will instead be resolved as meaning to do the pattern match using the rules of the current locale, and evaluate the rhs as an expression when doing the substitution. In 5.14, if you want the latter interpretation, you can write "el" instead.

Add \p{Titlecase} as a synonym for \p{Title}

This synonym is added for symmetry with the Unicode property names \p{Uppercase} and \p{Lowercase}.

New regular expression modifier option /aa

Doubling the /a regular expression modifier increases its effect, so that in case-insensitive matching, no ASCII character will match a non-ASCII character. For example, normally,

'k' =~ /\N{KELVIN SIGN}/i

will match; it won't under /aa.

New warnings categories for problematic (non-)Unicode code points.

Three new warnings subcategories of <utf8> have been added. These allow you to turn off warnings for their covered events, while allowing the other UTF-8 warnings to remain on. The three categories are: surrogate when UTF-16 surrogates are encountered; nonchar when Unicode non-character code points are encountered; and non_unicode when code points that are above the legal Unicode maximum of 0x10FFFF are encountered.

Incompatible Changes

Most \p{} properties are now immune from case-insensitive matching

For most Unicode properties, it doesn't make sense to have them match differently under /i case-insensitive matching than not. And doing so leads to unexpected results and potential security holes. For example


could previously match non-ASCII characters because of the Unicode matching rules. There were a number of bugs in this feature until an earlier release in the 5.13 series. Now this release reverts, and removes the feature completely except for the few properties where people have come to expect it, namely the ones where casing is an integral part of their functionality, such as m/\p{Uppercase}/i and m/\p{Lowercase}/i, both of which match the exact same code points, namely those matched by m/\p{Cased}/i. Details are in "Unicode Properties" in perlrecharclass.

User-defined property handlers that need to match differently under /i must change to read the new boolean parameter passed it which is non-zero if case-insensitive matching is in effect; 0 if not. See "User-Defined Character Properties" in perluniprops.

regex: \p{} in pattern implies Unicode semantics

Now, a Unicode property match specified in the pattern will indicate that the pattern is meant for matching according to Unicode rules (e40e74f)

add GvCV_set() and GvGP_set() macros and change GvGP()

This allows a future commit to eliminate some backref magic between GV and CVs, which will require complete control over assignment to the gp_cv slot.

If you've been using GvGP() in lvalue context this change will break your code, you should use GvGP_set() instead. (c43ae56)

_swash_inversion_hash is no longer exported as part of the API

This function shouldn't be called from XS code. (4c2e113)

Unreferenced objects in global destruction

The fix for [perl #36347], which made sure that destructors were called on unreferenced objects, broke the tests for three CPAN modules, which apparently rely on the bug.

To provide more time for fixing them (as this is such a minor bug), we have reverted the fix until after perl 5.14.0.

This resolves [perl #82542] and other related tickets.

close on shared pipes

The close function no longer waits for the child process to exit if the underlying file descriptor is still in use by another thread, to avoid deadlocks. It returns true in such cases.


Deprecated Modules

The following modules will be removed from the core distribution in a future release, and should be installed from CPAN instead. Distributions on CPAN which require these should add them to their prerequisites. The core versions of these modules warnings will issue a deprecation warning.

If you ship a packaged version of Perl, either alone or as part of a larger system, then you should carefully consider the repercussions of core module deprecations. You may want to consider shipping your default build of Perl with packages for some or all deprecated modules which install into vendor or site perl library directories. This will inhibit the deprecation warnings.

Alternatively, you may want to consider patching lib/ to provide deprecation warnings specific to your packaging system or distribution of Perl, consistent with how your packaging system or distribution manages a staged transition from a release where the installation of a single package provides the given functionality, to a later release where the system administrator needs to know to install multiple packages to get that same functionality.

You can silence these deprecation warnings by installing the modules in question from CPAN. To install the latest version of all of them, just install Task::Deprecations::5_14.


We strongly recommend that you install and used Devel::NYTProf in preference, as it offers significantly improved profiling and reporting.

User-defined case-mapping

This feature is being deprecated due to its many issues, as documented in "User-Defined Case Mappings (for serious hackers only)" in perlunicode. It is planned to remove this feature in Perl 5.16. A CPAN module providing improved functionality is being prepared for release by the time 5.14 is.

Modules and Pragmata

New Modules and Pragmata

Updated Modules and Pragmata


Changes to Existing Documentation


perlhack and perlrepository





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

"\b{" is deprecated; use "\b\{" instead
"\B{" is deprecated; use "\B\{" instead

Use of an unescaped "{" immediately following a \b or \B is now deprecated so as to reserve its use for Perl itself in a future release.

regcomp: Add warning if \p is used under locale. (fb2e24c)

\p implies Unicode matching rules, which are likely going to be different than the locale's.

panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries

This new error is triggered if a destructor called on an object in a typeglob that is being freed creates a new typeglob entry containing an object with a destructor that creates a new entry containing an object....

refcnt: fd %d%s

This new error only occurs if a internal consistency check fails when a pipe is about to be closed.

Changes to Existing Diagnostics

Utility Changes


Configuration and Compilation


Platform Support

Platform-Specific Notes

  • The test-prep build target now depends on pod/perltoc.pod to allow the t/porting/buildtoc.t test to run successfully.

  • [perl #82988] Skip hanging taint.t test on MirBSD 10 (1fb83d0)

    Skip a hanging test under MirBSD that was already being skipped under OpenBSD.

  • Previously if you build perl with a shared on MirBSD (the default config), it will work up to the installation; however, once installed, it will be unable to find libperl. Treat path handling like in the other BSD dialects.

Internal Changes

Selected Bug Fixes


Perl 5.13.10 represents approximately one month of development since Perl 5.13.9 and contains approximately 63000 lines of changes across 609 files from 38 authors and committers:

Abigail, Alexander Hartmaier, brian d foy, Charles Bailey, Chip Salzenberg, Chris 'BinGOs' Williams, Craig A. Berry, Curtis Jewell, Dave Rolsky, David Golden, David Leadbeater, David Mitchell, David Wheeler, Father Chrysostomos, Florian Ragwitz, Franz Fasching, George Greer, H.Merijn Brand, Hongwen Qiu, Hugo van der Sanden, Jay Hannah, Jesse Vincent, Karl Williamson, Larwan Berke, Leon Timmermans, Michael Breen, Michael Stevens, Nicholas Clark, Noirin Shirley, Paul Evans, Peter John Acklam, Ricardo Signes, Robin Barker, Steven Schubiger, Tom Christiansen, Tony Cook, Zsbán Ambrus and Ævar Arnfjörð Bjarmason

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 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.