++ed by:

179 PAUSE users
175 non-PAUSE users.

Chris Williams
and 1 contributors


perl5275delta - what is new for perl v5.27.5


This document describes differences between the 5.27.4 release and the 5.27.5 release.

If you are upgrading from an earlier release such as 5.27.3, first read perl5274delta, which describes differences between 5.27.3 and 5.27.4.

Incompatible Changes

Subroutines no longer need typeglobs

Perl 5.22.0 introduced an optimization allowing subroutines to be stored in packages as simple sub refs, not requiring a full typeglob (thus potentially saving large amounts of memeory). However, the optimization was flawed: it only applied to the main package.

This optimization has now been extended to all packages. This may break compatibility with introspection code that looks inside stashes and expects everything in them to be a typeglob.

When this optimization happens, the typeglob still notionally exists, so accessing it will cause the stash entry to be upgraded to a typeglob. The optimization does not apply to XSUBs or exported subroutines, and calling a method will undo it, since method calls cache things in typeglobs.

[perl #129916] [perl #132252]

Performance Enhancements

  • Calls to require for an already loaded module are now slightly faster. [perl #132171]

Modules and Pragmata

Updated Modules and Pragmata

  • arybase has been upgraded from version 0.13 to 0.14.

  • B has been upgraded from version 1.69 to 1.70.

  • B::Concise has been upgraded from version 1.001 to 1.002.

  • B::Deparse has been upgraded from version 1.42 to 1.43.

  • Config::Perl::V has been upgraded from version 0.28 to 0.29.

  • Digest::SHA has been upgraded from version 5.96 to 5.98.

  • Encode has been upgraded from version 2.92 to 2.93.

  • encoding has been upgraded from version 2.20 to 2.21.

  • File::Fetch has been upgraded from version 0.52 to 0.54.

  • File::Path has been upgraded from version 2.14 to 2.15.

  • List::Util has been upgraded from version 1.48 to 1.49.

  • Locale::Codes has been upgraded from version 3.52 to 3.54.

  • Math::BigInt has been upgraded from version 1.999806 to 1.999811.

  • Math::BigInt::FastCalc has been upgraded from version 0.5005 to 0.5006.

  • Module::CoreList has been upgraded from version 5.20170920 to 5.20171020.

  • NEXT has been upgraded from version 0.67 to 0.67_01.

  • Pod::Perldoc has been upgraded from version 3.28 to 3.2801.

  • POSIX has been upgraded from version 1.77 to 1.78.

  • Scalar::Util has been upgraded from version 1.48 to 1.49.

  • Sub::Util has been upgraded from version 1.48 to 1.49.

  • Sys::Hostname has been upgraded from version 1.20 to 1.21.

  • Test::Simple has been upgraded from version 1.302073 to 1.302103.

  • Time::HiRes has been upgraded from version 1.9743 to 1.9746.

  • Time::Piece has been upgraded from version 1.3201 to 1.3202.

Platform Support

Platform-Specific Notes


Compilation on CentOS 5 is now fixed.

Selected Bug Fixes

  • Calling exec PROGRAM LIST with an empty LIST has been fixed. This should call execvp() with an empty argv array (containing only the terminating NULL pointer), but was instead just returning false (and not setting $!). [perl #131730]

  • The gv_fetchmeth_sv C function stopped working properly in Perl 5.22 when fetching a constant with a UTF-8 name if that constant subroutine was stored in the stash as a simple scalar reference, rather than a full typeglob. This has been corrected.

  • Single-letter debugger commands followed by an argument which starts with punctuation (e.g. p$^V and x@ARGV) now work again. They had been wrongly requiring a space between the command and the argument. [perl #120174]

  • splice now throws an exception ("Modification of a read-only value attempted") when modifying a read-only array. Until now it had been silently modifying the array. The new behaviour is consistent with the behaviour of push and unshift. [perl #131000]


Perl 5.27.5 represents approximately 4 weeks of development since Perl 5.27.4 and contains approximately 29,000 lines of changes across 430 files from 20 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 17,000 lines of changes to 340 .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 5.27.5:

Aaron Crane, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dmitry Ulanov, Dominic Hargreaves, Father Chrysostomos, H.Merijn Brand, James E Keenan, John P. Linderman, John SJ Anderson, Lukas Mai, Nicolas R., Sawyer X, Smylers, Steve Hay, Tom Hukins, 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 perl bug database at https://rt.perl.org/ . 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 see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.

Give Thanks

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the perlthanks program:


This will send an email to the Perl 5 Porters list with your show of thanks.


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.