PERL5161DELTA(1)

💖 perl5161delta — bestie, it's the tea on perl v5.16.1 💖

okay so you're here for PERL5161DELTA(1), the manual page that spills everything about what is new for perl v5.16.1. pull up a chair, grab a boba, we're doing this together 🧋✨

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🌸 DESCRIPTION 🌸

So basically this doc is the gossip between the 5.16.0 release and the 5.16.1 release. That's it, that's the whole vibe.

But hmm, if you're upgrading from something earlier, like from 5.14.0? bestie, stop, do not pass go — go read perl5160delta first, because that one explains the glow-up from 5.14.0 to 5.16.0. you need that context, fr fr.

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🔒 Security 🔒

an off-by-two error in Scalar-List-Util has been fixed

the fix landed in Scalar-List-Util 1.23_04, and perl 5.16.1 ships with Scalar-List-Util 1.25. an off-by-two?? in this economy?? anyway it's fixed, we're slaying 💅

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🚫 Incompatible Changes 🚫

There are no changes intentionally incompatible with 5.16.0. literally zero, on purpose.

but listen — if any do exist, they're bugs, not features, and we're begging you to submit a report. check out "Reporting Bugs" below 👇

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📦 Modules and Pragmata 📦

Updated Modules and Pragmata

• Scalar::Util and List::Util have been upgraded from version 1.23 to version 1.25. glow up ✨
• B::Deparse has been updated from version 1.14 to 1.14_01. An "uninitialized" warning emitted by B::Deparse has been squashed [perl #113464]. not the warning getting deleted from the group chat 💀

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🛠️ Configuration and Compilation 🛠️

• Building perl with some Windows compilers used to fail due to a problem with miniperl's "glob" operator (which uses the "perlglob" program) deleting the PATH environment variable [perl #113798]. imagine just deleting PATH. the audacity. anyway, fixed 🙈

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🖥️ Platform Support 🖥️

Platform-Specific Notes

VMS — All C header files from the top-level directory of the distribution are now installed on VMS, providing consistency with a long-standing practice on other platforms. Previously only a subset were installed, which broke non-core extension builds for extensions that depended on the missing include files. VMS said "i want what they have" and honestly? valid. 👑

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🐛 Selected Bug Fixes 🐛

• A regression introduced in Perl v5.16.0 involving "tr/SEARCHLIST/REPLACEMENTLIST/" has been fixed. Only the first instance is supposed to be meaningful if a character appears more than once in "SEARCHLIST". Under some circumstances, the final instance was overriding all earlier ones. [perl #113584] — last one in was stealing the whole show, main character energy gone wrong 😭
• "B::COP::stashlen" has been added. This provides access to an internal field added in perl 5.16 under threaded builds. It was broken at the last minute before 5.16 was released [perl #113034]. last-minute chaos, we've all been there 🫶
• The re pragma will no longer clobber $_. [perl #113750] — hands off $_, bestie, that's mine 💅
• Unicode 6.1 published an incorrect alias for one of the Canonical_Combining_Class property's values (which range between 0 and 254). The alias "CCC133" should have been "CCC132". Perl now overrides the data file furnished by Unicode to give the correct value. Unicode typo'd and Perl said "i got u" 🎀
• Duplicating scalar filehandles works again. [perl #113764] — she's back and better 💖
• Under threaded perls, a runtime code block in a regular expression could corrupt the package name stored in the op tree, resulting in bad reads in "caller", and possibly crashes [perl #113060]. yeah that's a 💀 moment.
• For efficiency's sake, many operators and built-in functions return the same scalar each time. Lvalue subroutines and subroutines in the CORE:: namespace were allowing this implementation detail to leak through. "print &CORE::uc("a"), &CORE::uc("b")" used to print "BB". The same thing would happen with an lvalue subroutine returning the return value of "uc". Now the value is copied in such cases [perl #113044]. printing "BB" when you asked for "AB"?? not the plot twist we wanted 🔥 now it's copied, periodt.
• "__SUB__" now works in special blocks ("BEGIN", "END", etc.). ✨
• Formats that reference lexical variables from outside no longer result in crashes. no more crashing, we simply don't do that here 🌈

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🤔 Known Problems 🤔

There are no new known problems, but go consult "Known Problems" in perl5160delta to see the ones identified back in the 5.16.0 release. old problems, still iconic, still there.

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🫶 Acknowledgements 🫶

Perl 5.16.1 represents approximately 2 months of development since Perl 5.16.0 and contains approximately 14,000 lines of changes across 96 files from 8 authors. that's a whole lotta commits, bestie 😤

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 5.16.1:

Chris 'BinGOs' Williams, Craig A. Berry, Father Chrysostomos, Karl Williamson, Paul Johnson, Reini Urban, Ricardo Signes, Tony Cook.

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. y'all are seen and loved 🥹💖

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. CPAN, you ate. 👑

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

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📮 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. tiny but sufficient test case, that's the rule, we love a minimal repro 🎀

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.

okay that's a lot of words but the point is: security stuff goes to the private address, not the public one. iykyk 🔒

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👀 SEE ALSO 👀

• 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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and that's the whole page, bestie 💅✨ this was perl v5.42.3, dated 2026-08-03 — mwah, go forth and upgrade responsibly 🦋💖🌸