PERL5124DELTA(1)

💖 PERL5124DELTA 💖

okay bestie, welcome to the perl5124delta page — it's the tea on what's new for perl v5.12.4 ✨ (also this lives in the Perl Programmers Reference Guide, iykyk 🎀)

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🌸 DESCRIPTION 🌸

So this doc spills the differences between the 5.12.3 release and the 5.12.4 release. periodt.

If you're upgrading from an earlier release, like say 5.12.2, bestie you gotta read perl5123delta first — that one covers the glow-up from 5.12.2 to 5.12.3. And the major changes from 5.12.0? Those live in perl5120delta. no skipping ✋

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💀 Incompatible Changes 💀

Good news fr fr: there are no changes intentionally incompatible with 5.12.3. None. Zero. If any exist, they're literally bugs and reports are welcome 🫶

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🔥 Selected Bug Fixes 🔥

• So when strict "refs" mode is off, %{...} in rvalue context returns undef if its argument is undefined. But there was this optimisation added in Perl 5.12.0 to make keys %{...} faster when it's used as a boolean, and it just… didn't take that into account 😭 which meant keys %{+undef} (and keys %$foo when $foo is undefined) threw an error — and it should only be an error in strict mode, bestie. [perl #81750]
• lc, uc, lcfirst, and ucfirst no longer return untainted strings when the argument is tainted. This has been broken since perl 5.8.9 💅 [perl #87336]
• Fixed a case where it was possible that a freed buffer may have been read from when parsing a here document. yeah. that one. 🙈

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🎀 Modules and Pragmata 🎀

Module::CoreList has been upgraded from version 2.43 to 2.50. glow up ✨

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🧚 Testing 🧚

The cpan/CGI/t/http.t test script has been fixed so it works when the environment has HTTPS_* environment variables, such as HTTPS_PROXY. it was giving chaos, now it's giving functionality 💜

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📖 Documentation 📖

Updated the documentation for rand() in perlfunc to note that it is not cryptographically secure. important!! noted!! 👑

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🌈 Platform Specific Notes 🌈

Linux

Support Ubuntu 11.04's new multi-arch library layout. we love to see it 🐧

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👑 Acknowledgements 👑

Perl 5.12.4 represents approximately 5 months of development since Perl 5.12.3 and contains approximately 200 lines of changes across 11 files from 8 authors. the math is mathing.

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 5.12.4:

Andy Dougherty, David Golden, David Leadbeater, Father Chrysostomos, Florian Ragwitz, Jesse Vincent, Leon Brocard, Zsbán Ambrus.

absolute icons, every single one 🫶⭐

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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.

🚨 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 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.

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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 vibe check bestie 💅 this was perl v5.42.3, dated 2026-08-03, and honestly? iconic. mwah 🎀💖✨