man > perl5203delta(1)

PERL5203DELTA(1)                  Perl Programmers Reference Guide                  PERL5203DELTA(1)

NAME
       perl5203delta - what is new for perl v5.20.3

DESCRIPTION
       This document describes differences between the 5.20.2 release and the 5.20.3 release.

       If you are upgrading from an earlier release such as 5.20.1, first read perl5202delta, which
       describes differences between 5.20.1 and 5.20.2.

Incompatible Changes
       There are no changes intentionally incompatible with 5.20.2.  If any exist, they are bugs,
       and we request that you submit a report.  See "Reporting Bugs" below.

Modules and Pragmata
   Updated Modules and Pragmata
       •   Errno has been upgraded from version 1.20_05 to 1.20_06.

           Add  -P  to  the  pre-processor  command-line on GCC 5.  GCC added extra line directives,
           breaking     parsing     of      error      code      definitions.       [GH      #14491]
           <https://github.com/Perl/perl5/issues/14491>

       •   Module::CoreList has been upgraded from version 5.20150214 to 5.20150822.

           Updated to cover the latest releases of Perl.

       •   perl5db.pl has been upgraded from 1.44 to 1.44_01.

           The     debugger     would     cause     an     assertion     failure.     [GH    #14605]
           <https://github.com/Perl/perl5/issues/14605>

Documentation
   Changes to Existing Documentation
       perlfunc

       •   Mention that study() is currently a no-op.

       perlguts

       •   The OOK example has been updated to account for COW changes and a change in  the  storage
           of the offset.

       perlhacktips

       •   Documentation  has  been added illustrating the perils of assuming the contents of static
           memory pointed to by the return values of Perl wrappers for C library  functions  doesn't
           change.

       perlpodspec

       •   The  specification  of  the POD language is changing so that the default encoding of PODs
           that aren't in UTF-8  (unless  otherwise  indicated)  is  CP1252  instead  of  ISO-8859-1
           (Latin1).

Utility Changes
   h2ph
       •   h2ph now handles hexadecimal constants in the compiler's predefined macro definitions, as
           visible in $Config{cppsymbols}.  [GH #14491] <https://github.com/Perl/perl5/issues/14491>

Testing
       •   t/perf/taint.t  has  been  added  to  see  if optimisations with taint issues are keeping
           things fast.

       •   t/porting/re_context.t has been added to test that utf8 and its dependencies only use the
           subset of  the  "$1..$n"  capture  vars  that  Perl_save_re_context()  is  hard-coded  to
           localize,  because that function has no efficient way of determining at runtime what vars
           to localize.

Platform Support
   Platform-Specific Notes
       Win32
           •   Previously, when compiling with a 64-bit Visual C++, every Perl XS module  (including
               CPAN  ones)  and Perl aware C file would unconditionally have around a dozen warnings
               from hv_func.h.  These warnings have been silenced.  GCC  (all  bitness)  and  32-bit
               Visual C++ were not affected.

           •   miniperl.exe  is  now  built  with  -fno-strict-aliasing,  allowing  64-bit builds to
               complete with GCC 4.8.  [GH #14556] <https://github.com/Perl/perl5/issues/14556>

Selected Bug Fixes
       •   Repeated global  pattern  matches  in  scalar  context  on  large  tainted  strings  were
           exponentially  slow  depending  on the current match position in the string.  [GH #14238]
           <https://github.com/Perl/perl5/issues/14238>

       •   The original visible value of $/ is now preserved when it is set  to  an  invalid  value.
           Previously  if  you  set $/ to a reference to an array, for example, perl would produce a
           runtime error and not set PL_rs, but Perl code  that  checked  $/  would  see  the  array
           reference.  [GH #14245] <https://github.com/Perl/perl5/issues/14245>

       •   Perl 5.14.0 introduced a bug whereby "eval { LABEL: }" would crash.  This has been fixed.
           [GH #14438] <https://github.com/Perl/perl5/issues/14438>

       •   Extending  an  array cloned from a parent thread could result in "Modification of a read-
           only value attempted" errors when attempting to modify the  new  elements.   [GH  #14605]
           <https://github.com/Perl/perl5/issues/14605>

       •   Several  cases  of  data used to store environment variable contents in core C code being
           potentially   overwritten   before   being   used   have   been   fixed.    [GH   #14476]
           <https://github.com/Perl/perl5/issues/14476>

       •   UTF-8  variable names used in array indexes, unquoted UTF-8 HERE-document terminators and
           UTF-8     function     names     all     now     work     correctly.      [GH     #14601]
           <https://github.com/Perl/perl5/issues/14601>

       •   A  subtle  bug  introduced  in  Perl  5.20.2  involving  UTF-8 in regular expressions and
           sometimes causing a crash has been fixed.  A new test script has been added to test  this
           fix; see under "Testing".  [GH #14600] <https://github.com/Perl/perl5/issues/14600>

       •   Some  patterns starting with "/.*..../" matched against long strings have been slow since
           Perl 5.8, and some of the form "/.*..../i" have been slow since Perl 5.18.  They are  now
           all fast again.  [GH #14475] <https://github.com/Perl/perl5/issues/14475>

       •   Warning  fatality  is  now  ignored  when  rewinding  the  stack.  This prevents infinite
           recursion when the now fatal error also causes  rewinding  of  the  stack.   [GH  #14319]
           <https://github.com/Perl/perl5/issues/14319>

       •   setpgrp($nonzero)  (with  one  argument)  was  accidentally  changed in Perl 5.16 to mean
           setpgrp(0).  This has been fixed.

       •   A   crash    with    "%::=();    J->${\"::"}"    has    been    fixed.     [GH    #14790]
           <https://github.com/Perl/perl5/issues/14790>

       •   Regular    expression   possessive   quantifier   Perl   5.20   regression   now   fixed.
           "qr/"PAT"{"min,max"}+""/"     is     supposed     to      behave      identically      to
           "qr/(?>"PAT"{"min,max"})/".  Since Perl 5.20, this didn't work if min and max were equal.
           [GH #14857] <https://github.com/Perl/perl5/issues/14857>

       •   Code  like  "/$a[/"  used  to  read the next line of input and treat it as though it came
           immediately after the opening bracket.  Some invalid code consequently  would  parse  and
           run,   but   some   code  caused  crashes,  so  this  is  now  disallowed.   [GH  #14462]
           <https://github.com/Perl/perl5/issues/14462>

Acknowledgements
       Perl 5.20.3 represents approximately 7 months of development since Perl 5.20.2  and  contains
       approximately 3,200 lines of changes across 99 files from 26 authors.

       Excluding  auto-generated  files,  documentation  and release tools, there were approximately
       1,500 lines of changes to 43 .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 5.20.3:

       Alex Vandiver, Andy Dougherty, Aristotle Pagaltzis, Chris 'BinGOs' Williams, Craig A.  Berry,
       Dagfinn Ilmari Mannsåker, Daniel Dragan, David Mitchell, Father Chrysostomos, H.Merijn Brand,
       James  E Keenan, James McCoy, Jarkko Hietaniemi, Karen Etheridge, Karl Williamson, kmx, Lajos
       Veres, Lukas Mai, Matthew Horsfall, Petr Písař, Randy  Stauner,  Ricardo  Signes,  Sawyer  X,
       Steve Hay, 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  articles  recently  posted  to  the
       comp.lang.perl.misc  newsgroup and the perl bug database at https://rt.perl.org/ .  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                                 2026-06-12                             PERL5203DELTA(1)