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perldelta - what is new for perl v5.27.6


This document describes differences between the 5.27.5 release and the 5.27.6 release.

If you are upgrading from an earlier release such as 5.27.4, first read perl5275delta, which describes differences between 5.27.4 and 5.27.5.

Core Enhancements ^

Initialisation of aggregate state variables

A persistent lexical array or hash variable can now be initialized, by an expression such as state @a = qw(x y z). Initialization of a list of persistent lexical variables is still not possible.

Full-size inode numbers

On platforms where inode numbers are of a type larger than perl's native integer numerical types, stat will preserve the full content of large inode numbers by returning them in the form of strings of decimal digits. Exact comparison of inode numbers can thus be achieved by comparing with eq rather than ==. Comparison with ==, and other numerical operations (which are usually meaningless on inode numbers), work as well as they did before, which is to say they fall back to floating point, and ultimately operate on a fairly useless rounded inode number if the real inode number is too big for the floating point format.

Incompatible Changes ^

Yada-yada is now strictly a statement

By the time of its initial stable release in Perl 5.12, the ... (yada-yada) operator was explicitly intended to serve as a statement, not an expression. However, the original implementation was confused on this point, leading to inconsistent parsing. The operator was accidentally accepted in a few situations where it did not serve as a complete statement, such as

    ... . "foo";
    ... if $a < $b;

The parsing has now been made consistent, permitting yada-yada only as a statement. Affected code can use do{...} to put a yada-yada into an arbitrary expression context.

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.

(This change actually happened in perl 5.27.5 but was omitted from its perldelta.)

[perl #129916] [perl #132252]

Sort algorithm can no longer be specified

Since Perl 5.8, the sort pragma has had subpragmata _mergesort, _quicksort, and _qsort that can be used to specify which algorithm perl should use to implement the sort builtin. This was always considered a dubious feature that might not last, hence the underscore spellings, and they were documented as not being portable beyond Perl 5.8. These subpragmata have now been deleted, and any attempt to use them is an error. The sort pragma otherwise remains, and the algorithm-neutral stable subpragma can be used to control sorting behaviour. [perl #119635]

Performance Enhancements ^

Modules and Pragmata ^

Key highlights in this release across several modules:

Removal of use vars

The usage of use vars has been discouraged since the introduction of our in Perl 5.6.0. Where possible the usage of this pragma has now been removed from the Perl source code.

This had a slight effect (for the better) on the output of WARNING_BITS in B::Deparse.

Use of DynaLoader changed to XSLoader in many modules

XSLoader is more modern, and most modules already require perl 5.6 or greater, so no functionality is lost by switching. In some cases, we have also made changes to the local implementation that may not be reflected in the version on CPAN due to a desire to maintain more backwards compatibility.

Updated Modules and Pragmata

Documentation ^

Changes to Existing Documentation

We have attempted to update the documentation to reflect the changes listed in this document. If you find any we have missed, send email to

Additionally, the following selected changes have been made:

Diagnostics ^

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.

Changes to Existing Diagnostics

Utility Changes ^


Configuration and Compilation ^

C89 requirement

Perl has been documented as requiring a C89 compiler to build since October 1998. A variety of simplifications have now been made to Perl's internals to rely on the features specified by the C89 standard. We believe that this internal change hasn't altered the set of platforms that Perl builds on, but please report a bug if Perl now has new problems building on your platform.

New probes

Packaging ^

For the past few years we have released perl using three different archive formats: bzip (.bz2), LZMA2 (.xz) and gzip (.gz). Since xz compresses better and decompresses faster, and gzip is more compatible and uses less memory, we have dropped the .bz2 archive format with this release. (If this poses a problem, do let us know; see "Reporting Bugs", below.)

Platform Support ^

Discontinued Platforms

PowerUX / Power MAX OS

Compiler hints and other support for these apparently long-defunct platforms has been removed.

Platform-Specific Notes


Visual C++ compiler version detection has been improved to work on non-English language systems.

Internal Changes ^

Selected Bug Fixes ^

Errata From Previous Releases ^

Acknowledgements ^

Perl 5.27.6 represents approximately 4 weeks of development since Perl 5.27.5 and contains approximately 110,000 lines of changes across 1,100 files from 30 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 20,000 lines of changes to 430 .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 5.27.6:

Aaron Crane, Andrew Fresh, Ask Bjöern Hansen, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, David Cantrell, David Mitchell, Dominic Hargreaves, Father Chrysostomos, Harald Jörg, H.Merijn Brand, James E Keenan, Jarkko Hietaniemi, J. Nick Koston, John Lightsey, Karen Etheridge, Karl Williamson, Lukas Mai, Matthew Horsfall, Nicolas R., Paul Marquess, Sawyer X, Slaven Rezic, Steve Hay, Todd Rinaldo, 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 . 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 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.

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