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perldelta - what is new for perl v5.15.9


This document describes differences between the 5.15.8 release and the 5.15.9 release.

If you are upgrading from an earlier release such as 5.15.7, first read perl5158delta, which describes differences between 5.15.7 and 5.15.8.


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Core Enhancements

no feature; now means reset to default

no feature now resets to the default feature set. To disable all features (which is likely to be a pretty special-purpose request, since it presumably won't match any named set of semantics) you can now write no feature ':all'.


Malformed UTF-8 input could cause attempts to read beyond the end of the buffer

Two new XS-accessible functions, utf8_to_uvchr_buf() and utf8_to_uvuni_buf() are now available to prevent this, and the Perl core has been converted to use them. See "Internal Changes".

Incompatible Changes

no feature;

no feature; now means reset to default.


Literal "{" characters in regular expressions.

It has been documented that the current plans include requiring a literal "{" to be escaped: 5.18 will emit deprecation warnings, and it will be required in 5.20.

XS functions utf8_to_uvchr() and utf8_to_uvuni()

Use utf8_to_uvchr_buf() and utf8_to_uvuni_buf() instead. See "Internal Changes".

Performance Enhancements

  • Fix a slowdown in freeing nested hashes. This may speedup the exit of certain programs.

Modules and Pragmata

Updated Modules and Pragmata

  • attributes has been upgraded from version 0.17 to 0.18.

  • charnames has been upgraded from version 1.29 to 1.30.

  • feature has been upgraded from version 1.26 to 1.27.

    no feature; now means reset to default. The code has been refactored to reduce duplication.

  • B::Deparse has been upgraded from version 1.12 to 1.13.

  • B::Lint has been upgraded from version 1.13 to 1.14.

  • CPAN::Meta has been upgraded from version 2.120351 to 2.120630.

  • CPANPLUS has been upgraded from version 0.9118 to 0.9121.

  • Data::Dumper has been upgraded from version 2.135_05 to 2.135_06.

  • Digest::SHA has been upgraded from version 5.70 to 5.71.

  • ExtUtils::CBuilder has been upgraded from version 0.280205 to 0.280206.

  • HTTP::Tiny has been upgraded from version 0.016 to 0.017.

  • Module::CoreList has been upgraded from version 2.60 to 2.65.

  • Pod::Html has been upgraded from version 1.14 to 1.1501.

  • Pod::Perldoc has been upgraded from version 3.15_15 to 3.17.

  • Pod::Simple has been upgraded from version 3.19 to 3.20.

  • Socket has been upgraded from version 1.98 to 2.000.

  • Term::ReadLine has been upgraded from version 1.08 to 1.09.

    Term::ReadLine now optionally integrates with event loops other than Tk.

  • Unicode::Collate has been upgraded from version 0.87 to 0.89.

  • Unicode::Normalize has been upgraded from version 1.13 to 1.14.

  • Unicode::UCD has been upgraded from version 0.41 to 0.42.

  • XS::APItest has been upgraded from version 0.36 to 0.37.


There has been no significant change in the documentation between 5.15.8 and 5.15.9.


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

Compared to 5.15.8, 5.15.9 does not introduce new errors.

New Warnings

Compared to 5.15.8, 5.15.9 does not introduce new warnings, but see "Changes to Existing Diagnostics"

Changes to Existing Diagnostics

Utility Changes

No utilities changed between 5.15.8 and 5.15.9.

Configuration and Compilation

  • perlfunc.html is now being generated again. [perl #107870]


  • t/op/require_37033.t has been added, to test that require always closes the file handle that it opens. Previously, it had been leaking the file handle if it happened to have file descriptor 0, which would happen if require was called (explicitly or implicitly) when STDIN had been closed.

Platform Support

There have been no changes to Perl's support of various platforms between 5.15.8 and 5.15.9.

Internal Changes

  • Two new functions utf8_to_uvchr_buf() and utf8_to_uvuni_buf() have been added. These are the same as utf8_to_uvchr and utf8_to_uvuni (which are now deprecated), but take an extra parameter that is used to guard against reading beyond the end of the input string. See "utf8_to_uvchr_buf" in perlapi and "utf8_to_uvuni_buf" in perlapi.

  • The regular expression engine now does TRIE case insensitive matches under Unicode. This may change the output of use re 'debug';, and will speed up various things.

Selected Bug Fixes

  • Takri now matches two more characters under the Script_Extensions property. This corrects a Unicode 6.1 omission.

  • perlfunc.html is now being generated again. [perl #107870]

  • $$ is no longer tainted. Since this value comes directly from getpid(), it is always safe.

  • Fix leaking a file handle. [perl #37033]

  • An off-by-one error caused /[:upper:]/ and /[:punct:]/ to unexpectedly match characters with code points above 255. This has been rectified. [perl 111400].

  • (?foo: ...) no longer loses passed in character set.

  • Allow attributes to set :lvalue on a defined sub. [perl 107366].

  • die; with a non-reference, non-string value in $@ now properly propagates that value [perl #111654].

Known Problems

This is a list of some significant unfixed bugs, which need to be resolved before 5.16.0

op/sigdispatch.t fails alarm test 14 and gets killed [perl #89718]

Perl crash due to wrong delimiter in PATH environment [perl #94846]

It's possible to crash perl under Win32 if the wrong delimiter is used.

Corrupt UTF8 [perl #79960, #100058]

It is possible to read an invalid UTF8 character, but have it marked valid, or to incorrectly read UTF8 characters if $/ is set to read fixed length records.

UTF8 patches for 5.16 [perl #107008]

Brian Fraser's work on UTF8 needs further integration.

eval { 'fork()' } is broken on Windows [perl #109718]

This is a known test failure to be fixed before 5.16.0.

Warnings from cpan/IO-Compress [perl #110736]

Some tests in cpan/IO-Compress/t/cz-03zlib-v1.t issues a "isn't numeric" warning in blead, but not in maint.

Pod-Html test failures on Windows.

A number of tests for Pod::Html fail under Windows, due to an incorrect assumption by the test scripts about capitalization of the network drive.


Perl 5.15.9 represents approximately 4 weeks of development since Perl 5.15.8 and contains approximately 79,000 lines of changes across 530 files from 23 authors.

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 5.15.9:

Aaron Crane, Abigail, Chris 'BinGOs' Williams, Craig A. Berry, Dave Rolsky, David Cantrell, David Golden, David Mitchell, Eric Brine, Father Chrysostomos, Florian Ragwitz, James E Keenan, Jesse Vincent, Karl Williamson, Marc Green, Max Maischein, Nicholas Clark, Pau Amma, Reini Urban, Ricardo Signes, Tony Cook, Yves Orton, Zefram.

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 http://rt.perl.org/perlbug/ . There may also be information at http://www.perl.org/ , 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 perlbug@perl.org 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 perl5-security-report@perl.org. 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.