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Source   Latest Release: perl-5.26.0-RC2


perl5257delta - what is new for perl v5.25.7


This document describes differences between the 5.25.6 release and the 5.25.7 release.

If you are upgrading from an earlier release such as 5.25.5, first read perl5256delta, which describes differences between 5.25.5 and 5.25.6.

Core Enhancements ^

Indented Here-documents

This adds a new modifier '~' to here-docs that tells the parser that it should look for /^\s*$DELIM\n/ as the closing delimiter.

These syntaxes are all supported:

    <<~ 'EOF';
    <<~ "EOF";
    <<~ `EOF`;

The '~' modifier will strip, from each line in the here-doc, the same whitespace that appears before the delimiter.

Newlines will be copied as is, and lines that don't include the proper beginning whitespace will cause perl to croak.

For example:

    if (1) {
      print <<~EOF;
        Hello there

prints "Hello there\n" with no leading whitespace.

'.' and @INC

Perl now provides a way to build perl without . in @INC by default. If you want this feature, you can build with -Ddefault_inc_excludes_dot

Because the testing / make process for perl modules do not function well with . missing from @INC, Perl now supports the environment variable PERL_USE_UNSAFE_INC=1 which makes Perl behave as it previously did, returning . to @INC in all child processes.

WARNING: PERL_USE_UNSAFE_INC has been provided during the perl 5.25 development cycle and is not guaranteed to function in perl 5.26.

create a safer utf8_hop() called utf8_hop_safe()

Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after the end of the supplied buffer.

Fix taint handling in list assignment

commit v5.25.6-79-gb09ed99 reworked list assignment, and accidentally broke taint handling at the same time.


@{^CAPTURE} exposes the capture buffers of the last match as an array. So $1 is ${^CAPTURE}[0].

%{^CAPTURE} is the equivalent to %+ (ie named captures)

%{^CAPTURE_ALL} is the equivalent to %- (ie all named captures).

op.c: silence compiler warning in fold_constants()

    op.c: In function ‘S_fold_constants’:
    op.c:4374:28: warning: argument ‘o’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Wclobbered]
     S_fold_constants(pTHX_ OP *o)

This warning has been silenced.

Performance Enhancements ^

Modules and Pragmata ^

Updated Modules and Pragmata

Documentation ^

Changes to Existing Documentation












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 ^

Testing ^

Platform Support ^

Platform-Specific Notes


don't treat -Dprefix=/usr as special, instead require an extra option -Ddarwin_distribution to produce the same results.


Finish removing POSIX deprecated functions.


OS X El Capitan doesn't implement the clock_gettime() or clock_getres() APIs, emulate them as necessary.


Deprecated syscall(2) on macOS 10.12.


Several tests have been updated to work (or be skipped) on EBCDIC platforms.


Net::Ping UDP test is skipped on HP-UX.


Move _pDEPTH and _aDEPTH after config.h otherwise DEBUGGING may not be defined yet.

VAXC has not been a possibility for a good long while, and the versions of the DEC/Compaq/HP/VSI C compiler that report themselves as "DEC" in a listing file are 15 years or more out-of-date and can be safely desupported.

VMS And Win32

Fix some breakage, add 'undef' value for default_inc_excludes_dot in build scripts.


Drop support for Linux a.out Linux has used ELF for over twenty years.


Test fixes and minor updates.

Account for lack of inf, nan, and -0.0 support.


fp definitions have been updated.

OpenBSD 6

OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO. Make sure this is accounted for.


t/uni/overload.t: Skip hanging test on FreeBSD.

Internal Changes ^

Selected Bug Fixes ^

Acknowledgements ^

Perl 5.25.7 represents approximately 4 weeks of development since Perl 5.25.6 and contains approximately 83,000 lines of changes across 630 files from 26 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 13,000 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 5.25.7:

Aaron Crane, Abigail, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Collins, Dave Rolsky, David Mitchell, Hauke D, H.Merijn Brand, Hugo van der Sanden, James E Keenan, Jarkko Hietaniemi, Karl Williamson, Lukas Mai, Matthew Horsfall, Nicolas R., Stefan Seifert, Steve Hay, Todd Rinaldo, Tony Cook, 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 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.


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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