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


       perl5203delta - what is new for perl v5.20.3


       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
       o   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] <>

       o   Module::CoreList has been upgraded from version 5.20150214 to

           Updated to cover the latest releases of Perl.

       o has been upgraded from 1.44 to 1.44_01.

           The debugger would cause an assertion failure.  [GH #14605]


   Changes to Existing Documentation

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


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


       o   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.


       o   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

       o   h2ph now handles hexadecimal constants in the compiler's predefined
           macro definitions, as visible in $Config{cppsymbols}.  [GH #14491]


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

       o   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
           o   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.

           o   miniperl.exe is now built with -fno-strict-aliasing, allowing
               64-bit builds to complete with GCC 4.8.  [GH #14556]

Selected Bug Fixes

       o   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]

       o   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] <>

       o   Perl 5.14.0 introduced a bug whereby "eval { LABEL: }" would crash.
           This has been fixed.  [GH #14438]

       o   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]

       o   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]

       o   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]

       o   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] <>

       o   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] <>

       o   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]

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

       o   A crash with "%::=(); J->${\"::"}" has been fixed.  [GH #14790]

       o   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]

       o   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]


       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

       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 Mannsaaker, 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 PisaX, 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 .  There may also be information at , 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 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  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.


       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 v5.34.0                      2021-05-04                PERL5203DELTA(1pm)

perl 5.34.0 - Generated Thu Feb 24 19:11:34 CST 2022
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