man > PERL5121DELTA(1)

PERL5121DELTA(1)                  Perl Programmers Reference Guide                  PERL5121DELTA(1)

NAME
       perl5121delta - what is new for perl v5.12.1

DESCRIPTION
       This document describes differences between the 5.12.0 release and the 5.12.1 release.

       If you are upgrading from an earlier release such as 5.10.1, first read perl5120delta, which
       describes differences between 5.10.0 and 5.12.0.

Incompatible Changes
       There are no changes intentionally incompatible with 5.12.0. If any incompatibilities with
       5.12.0 exist, they are bugs. Please report them.

Core Enhancements
       Other than the bug fixes listed below, there should be no user-visible changes to the core
       language in this release.

Modules and Pragmata
   Pragmata Changes
       •   We fixed exporting of "is_strict" and "is_lax" from version.

           These  were being exported with a wrapper that treated them as method calls, which caused
           them to fail.  They are just functions, are documented  as  such,  and  should  never  be
           subclassed, so this patch just exports them directly as functions without the wrapper.

   Updated Modules
       •   We  upgraded  CGI  to version 3.49 to incorporate fixes for regressions introduced in the
           release we shipped with Perl 5.12.0.

       •   We upgraded Pod::Simple to version 3.14 to get an improvement to \C\<\< \>\> parsing.

       •   We made a small fix to the CPANPLUS  test  suite  to  fix  an  occasional  spurious  test
           failure.

       •   We upgraded Safe to version 2.27 to wrap coderefs returned by reval() and rdo().

Changes to Existing Documentation
       •   We added the new maintenance release policy to perlpolicy

       •   We've clarified the multiple-angle-bracket construct in the spec for POD in perlpodspec

       •   We added a missing explanation for a warning about ":=" to perldiag

       •   We removed a false claim in perlunitut that all text strings are Unicode strings in Perl.

       •   We updated the GitHub mirror link in perlrepository to mirrors/perl, not github/perl

       •   We fixed a minor error in perl5114delta.

       •   We replaced a mention of the now-obsolete Switch with given/when.

       •   We improved documentation about $sitelibexp/sitecustomize.pl in perlrun.

       •   We corrected perlmodlib which had unintentionally omitted a number of modules.

       •   We  updated  the documentation for 'require' in perlfunc relating to putting Perl code in
           @INC.

       •   We reinstated some erroneously-removed documentation about quotemeta in perlfunc.

       •   We fixed an a2p example in perlutil.

       •   We filled in a blank in perlport with the release date of Perl 5.12.

       •   We fixed broken links in a number of perldelta files.

       •   The documentation for Carp incorrectly stated  that  the  $Carp::Verbose  variable  makes
           cluck generate stack backtraces.

       •   We fixed a number of typos in Pod::Functions

       •   We improved documentation of case-changing functions in perlfunc

       •   We corrected perlgpl to contain the correct version of the GNU General Public License.

Testing
   Testing Improvements
       •   t/op/sselect.t is now less prone to clock jitter during timing checks on Windows.

           sleep() time on Win32 may be rounded down to multiple of the clock tick interval.

       •   lib/blib.t and lib/locale.t: Fixes for test failures on Darwin/PPC

       •   perl5db.t: Fix for test failures when "Term::ReadLine::Gnu" is installed.

Installation and Configuration Improvements
   Configuration improvements
       •   We  updated  INSTALL  with  notes  about  how  to deal with broken dbm.h on OpenSUSE (and
           possibly other platforms)

Bug Fixes
       •   A bug in how we process filetest operations could  cause  a  segfault.   Filetests  don't
           always  expect  an  op on the stack, so we now use TOPs only if we're sure that we're not
           stat'ing the _ filehandle.  This is indicated by OPf_KIDS (as checked in ck_ftst).

           See also: <https://github.com/Perl/perl5/issues/10335>

       •   When deparsing a nextstate op that has both a change of package (relative to the previous
           nextstate) and a label, the package declaration is  now  emitted  first,  because  it  is
           syntactically impermissible for a label to prefix a package declaration.

       •   XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS

           See also: <http://rt.cpan.org/Public/Bug/Display.html?id=55049>

       •   utf8::is_utf8 now respects GMAGIC (e.g. $1)

       •   XS  code using fputc() or fputs(): on Windows could cause an error due to their arguments
           being swapped.

           See also: <https://github.com/Perl/perl5/issues/10156>

       •   We fixed a small bug in lex_stuff_pvn() that caused spurious syntax errors in an  obscure
           situation.   It  happened  when stuffing was performed on the last line of a file and the
           line ended with a statement that lacked a terminating semicolon.

           See also: <https://github.com/Perl/perl5/issues/10273>

       •   We fixed a bug that could cause \N{} constructs followed by  a  single  .  to  be  parsed
           incorrectly.

           See also: <https://github.com/Perl/perl5/issues/10367>

       •   We fixed a bug that caused when(scalar) without an argument not to be treated as a syntax
           error.

           See also: <https://github.com/Perl/perl5/issues/10287>

       •   We  fixed a regression in the handling of labels immediately before string evals that was
           introduced in Perl 5.12.0.

           See also: <https://github.com/Perl/perl5/issues/10301>

       •   We fixed a regression in  case-insensitive  matching  of  folded  characters  in  regular
           expressions introduced in Perl 5.10.1.

           See also: <https://github.com/Perl/perl5/issues/10193>

Platform Specific Notes
   HP-UX
       •   Perl now allows -Duse64bitint without promoting to use64bitall on HP-UX

   AIX
       •   Perl now builds on AIX 4.2

           The  changes required work around AIX 4.2s' lack of support for IPv6, and limited support
           for POSIX sigaction().

   FreeBSD 7
       •   FreeBSD 7 no longer contains /usr/bin/objformat.  At  build  time,  Perl  now  skips  the
           objformat check for versions 7 and higher and assumes ELF.

   VMS
       •   It's now possible to build extensions on older (pre 7.3-2) VMS systems.

           DCL  symbol  length was limited to 1K up until about seven years or so ago, but there was
           no particularly deep reason to prevent those older systems from configuring and  building
           Perl.

       •   We fixed the previously-broken "-Uuseperlio" build on VMS.

           We  were  checking  a  variable  that  doesn't exist in the non-default case of disabling
           perlio.  Now we only look at it when it exists.

       •   We fixed the -Uuseperlio command-line option in configure.com.

           Formerly it only  worked  if  you  went  through  all  the  questions  interactively  and
           explicitly answered no.

Known Problems
       •   "List::Util::first"  misbehaves  in the presence of a lexical $_ (typically introduced by
           "my $_" or implicitly by "given"). The variable which gets set for each iteration is  the
           package variable $_, not the lexical $_.

           A  similar  issue may occur in other modules that provide functions which take a block as
           their first argument, like

               foo { ... $_ ...} list

           See also: <https://github.com/Perl/perl5/issues/9798>

       •   "Module::Load::Conditional" and "version" have an unfortunate interaction which can cause
           "CPANPLUS" to crash when it encounters  an  unparseable  version  string.   Upgrading  to
           "CPANPLUS" 0.9004 or "Module::Load::Conditional" 0.38 from CPAN will resolve this issue.

Acknowledgements
       Perl 5.12.1 represents approximately four weeks of development since Perl 5.12.0 and contains
       approximately 4,000 lines of changes across 142 files from 28 authors.

       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 5.12.1:

       Ævar  Arnfjörð  Bjarmason,  Chris  Williams,  chromatic, Craig A. Berry, David Golden, Father
       Chrysostomos, Florian Ragwitz, Frank Wiegand, Gene Sullivan, Goro Fuji, H.Merijn Brand, James
       E Keenan, Jan Dubois, Jesse Vincent, Josh ben Jore, Karl Williamson,  Leon  Brocard,  Michael
       Schwern,  Nga  Tang  Chan,  Nicholas Clark, Niko Tyni, Philippe Bruhat, Rafael Garcia-Suarez,
       Ricardo Signes, Steffen Mueller, Todd Rinaldo, Vincent Pit and Zefram.

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 AT 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 AT 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.

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.

perl v5.38.2                                 2026-08-18                             PERL5121DELTA(1)