perldelta - what is new for perl v5.33.9


This document describes differences between the 5.33.8 release and the 5.33.9 release.

If you are upgrading from an earlier release such as 5.33.7, first read perl5338delta, which describes differences between 5.33.7 and 5.33.8.

Modules and Pragmata

Updated Modules and Pragmata

  • Data::Dumper has been upgraded from version 2.177 to 2.178.

  • ExtUtils::MakeMaker has been upgraded from version 7.60 to 7.62.

  • ExtUtils::ParseXS has been upgraded from version 3.42 to 3.43.

  • ExtUtils::Typemaps has been upgraded from version 3.38 to 3.43.

  • feature has been upgraded from version 1.63 to 1.64.

  • Module::CoreList has been upgraded from version 5.20210320 to 5.20210420.

  • NEXT has been upgraded from version 0.67_01 to 0.68.

  • perlfaq has been upgraded from version 5.20201107 to 5.20210411.

  • XS::APItest has been upgraded from version 1.15 to 1.16.


  • perlguts now explains in greater detail the need to consult SvUTF8 when calling SvPV (or variants). A new "How do I pass a Perl string to a C library?" section in the same document discusses when to use which style of macro to read an SV's string value.

    perlapi, perlguts, perlxs, and perlxstut now prefer SvPVbyte over SvPV.

  • References to Pumpking have been replaced with a more accurate term or Steering Council where appropriate.

  • perldiag now documents additional examples of "not imported" warnings.

  • The Perl Steering Council is now the fallback contact for security issues.

  • Simplify the split() documentation by removing the join()s from the examples (#18676)

    Remove join() from split() examples as it confuses the concepts

    split() is a very basic function, and the documentation should be simple for novinces. The split() documentation contains a lot of join() in the examples which only serve to muddle the concepts. This replaces the join() in the example with output in comments.


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.

New Diagnostics

New Warnings

Configuration and Compilation

  • Prevented incpath to spill into libpth

    - Use realpath if available.
    - This might catch more duplicate paths.
    - Only include real existing paths.
    - Filter inc paths out of libpth.

Platform Support

Platform-Specific Notes


Reading non-ASCII characters from the console when its codepage was set to 65001 (UTF-8) was broken due to a bug in Windows. A workaround for this problem has been implemented. [GH #18701]

Internal Changes

  • Corrected handling of double and long double parameters for perl's implementation of formatted output for -Dusequadmath builds.

    This applies to PerlIO_printf(), croak(), warn(), sv_catpvf() and their variants.

    Previously in quadmath builds, code like:

      PerlIO_printf(PerlIO_stderr(), "%g", somedouble);


      PerlIO_printf(PerlIO_stderr(), "%Lg", somelongdouble);

    would erroneously throw an exception "panic: quadmath invalid format ...", since the code added for quadmath builds assumed NVs were the only floating point format passed into these functions.

    This code would also process the standard C long double specifier L as if it expected an NV (__float128 for quadmath builds), resulting in undefined behaviour.

    These functions now correctly accept doubles, long doubles and NVs.

  • Previously the right operand of bitwise shift operators (shift amount) was implicitly cast from IV to int, but it might lead wrong results if IV does not fit in int.

    And also, shifting INT_MIN bits used to yield the shiftee unchanged (treated as 0-bit shift instead of negative shift).

Selected Bug Fixes

  • Setting %ENV now properly handles upgraded strings in the key. Previously Perl sent the SV's internal PV directly to the OS; now it will handle keys as it has handled values since 5.18: attempt to downgrade the string first; if that fails then warn and use the utf8 form.


Perl 5.33.9 represents approximately 4 weeks of development since Perl 5.33.8 and contains approximately 3,900 lines of changes across 190 files from 23 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 780 lines of changes to 82 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.33.9:

Dan Book, Dominic Hamon, E. Choroba, Ed J, Felipe Gasper, H.Merijn Brand, Hugo van der Sanden, James E Keenan, John Lightsey, Karen Etheridge, Karl Williamson, Marc Reisner, Max Maischein, Nicolas R., Paul Evans, Ricardo Signes, Richard Leach, Scott Baker, TAKAI Kousuke, Todd Rinaldo, Tomasz Konojacki, Tony Cook, Михаил Козачков.

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 open an issue at Be sure to trim your bug down to a tiny but sufficient test case.

If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, 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.