This document describes differences between the 5.13.4 release and the
       5.13.5 release.

       If you are upgrading from an earlier release such as 5.13.3, first read
       perl5134delta, which describes differences between 5.13.3 and 5.13.4.

Core Enhancements
   Adjacent pairs of nextstate opcodes are now optimized away
       Previously, in code such as

           use constant DEBUG => 0;

           sub GAK {
               warn if DEBUG;
               print "stuff\n";

       the ops for "warn if DEBUG;" would be folded to a "null" op
       ("ex-const"), but the "nextstate" op would remain, resulting in a
       runtime op dispatch of "nextstate", "nextstate", ...

       The execution of a sequence of "nextstate" ops is indistinguishable
       from just the last "nextstate" op so the peephole optimizer now
       eliminates the first of a pair of "nextstate" ops, except where the
       first carries a label, since labels must not be eliminated by the
       optimizer and label usage isn't conclusively known at compile time.

   API function to parse statements
       The "parse_fullstmt" function has been added to allow parsing of a
       single complete Perl statement.  See perlapi for details.

   API functions for accessing the runtime hinthash
       A new C API for introspecting the hinthash "%^H" at runtime has been
       added.  See "cop_hints_2hv", "cop_hints_fetchpvn",
       "cop_hints_fetchpvs", "cop_hints_fetchsv", and "hv_copy_hints_hv" in
       perlapi for details.

   C interface to "caller()"
       The "caller_cx" function has been added as an XSUB-writer's equivalent
       of "caller()".  See perlapi for details.

Incompatible Changes
   Magic variables outside the main package
       In previous versions of Perl, magic variables like $!, %SIG, etc. would
       'leak' into other packages.  So %foo::SIG could be used to access
       signals, "${"foo::!"}" (with strict mode off) to access C's "errno",

       This was a bug, or an 'unintentional' feature, which caused various ill
       effects, such as signal handlers being wiped when modules were loaded,

   C API changes
       The first argument of the C API function "Perl_fetch_cop_label" has
       changed from "struct refcounted he *" to "COP *", to better insulate
       the user from implementation details.

       This API function was marked as "may change", and likely isn't in use
       outside the core.  (Neither an unpacked CPAN, nor Google's codesearch,
       finds any other references to it.)

   Use of qw(...) as parentheses
       Historically the parser fooled itself into thinking that "qw(...)"
       literals were always enclosed in parentheses, and as a result you could
       sometimes omit parentheses around them:

           for $x qw(a b c) { ... }

       The parser no longer lies to itself in this way.  Wrap the list literal
       in parentheses, like:

           for $x (qw(a b c)) { ... }

Performance Enhancements
       o   Scalars containing regular expressions now only allocate the part
           of the "SV" body they actually use, saving some space.

       o   Compiling regular expressions has been made faster for the case
           where upgrading the regex to utf8 is necessary but that isn't known
           when the compilation begins.

Modules and Pragmata
   Updated Modules and Pragmata
           Upgraded from version 0.23 to 0.25.

           Upgraded from version 1.05 to 1.06.

           Upgraded from version 1.07 to 1.08.

           Upgraded from version 1.33_02 to 1.33_03.

       "warnings" and "warnings::register"
           Upgraded from version 1.10 to 1.11 and from version 1.01 to 1.02

           It is now possible to register warning categories other than the
           names of packages using "warnings::register".  See perllexwarn for
           more information.

           Upgraded from version 2.39 to 2.40.

           Upgraded from version 1.12 to 1.13.

           On some platforms with unusual header files, like Win32/gcc using
           mingw64 headers, some constants which weren't actually error
           numbers have been exposed by "Errno".  This has been fixed [perl
           #77416] <>.

           Upgraded from version 6.5601 to 6.57_05.

           Upgraded from version 0.84 to 0.85.

           Upgraded from version 0.08 to 0.09.

           Upgraded from version 1.89_01 to 1.95.

           This fixes, among other things, incorrect results when computing
           binomial coefficients [perl #77640]

           Upgraded from version 0.19 to 0.22.

           Upgraded from version 0.24 to 0.26.

           Upgraded from version 2.37 to 2.38.

           Upgraded from version 0.08 to 0.09.

           Upgraded from version 1.19 to 1.20.

           It now includes constants for POSIX signal constants.

           Upgraded from version 2.27 to 2.28.

           This fixes a possible infinite loop when looking for coderefs.

           Upgraded from version 0.96 to 0.97_01.

           Upgraded from version 1.03 to 1.04.

       o   Many of the optree construction functions are now documented.


       o   Expanded to cover many more popular books.


       o   perlfaq, perlfaq2, perlfaq4, perlfaq5, perlfaq6, perlfaq8, and
           perlfaq9 have seen various updates and modernizations.

       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
       o   Parsing code internal error (%s)

           New fatal error produced when parsing code supplied by an extension
           violated the parser's API in a detectable way.

       o   Use of qw(...) as parentheses is deprecated

           See "Use of qw(...) as parentheses" for details.

   Changes to Existing Diagnostics
       o   "warn" and "die" now produce 'Wide character' warnings when fed a
           character outside the byte range if STDERR is a byte-sized handle.

Utility Changes

       o   The use of a deprecated "goto" construct has been removed [perl
           #74404] <>.

       o   The new t/lib/universal.t script tests the Internal::* functions
           and other things in universal.c.

       o   A rare race condition in t/op/while_readdir.t has been fixed,
           stopping it from failing randomly when running tests in parallel.

       o   The new t/op/leaky-magic.t script tests that magic applied to
           variables in the main packages does not affect other packages.

Platform Support
   Platform-Specific Notes
           o   Make "PerlIOUnix_open" honour default permissions on VMS.

               When "perlio" became the default and "unixio" became the
               default bottom layer, the most common path for creating files

           C++ objects, which was removed in Perl 5.8.  Nowadays these macros
           do exactly nothing, so they shouldn't be used anymore.

           For compatibility, they are still defined for external "XS" code.
           Only extensions defining "PERL_CORE" must be updated now.

       o   "lex_stuff_pvs()" has been added as a convenience macro wrapping
           "lex_stuff_pvn()" for literal strings.

       o   The recursive part of the peephole optimizer is now hookable.

           In addition to "PL_peepp", for hooking into the toplevel peephole
           optimizer, a "PL_rpeepp" is now available to hook into the
           optimizer recursing into side-chains of the optree.

Selected Bug Fixes
       o   A regression introduced in Perl 5.12.0, making "my $x = 3; $x =
           length(undef)" result in $x set to 3 has been fixed.  $x will now
           be "undef".

       o   A fatal error in regular expressions when processing UTF-8 data has
           been fixed [perl #75680]

       o   An erroneous regular expression engine optimization that caused
           regex verbs like *COMMIT to sometimes be ignored has been removed.

       o   The Perl debugger now also works in taint mode [perl #76872]

       o   Several memory leaks in cloning and freeing threaded Perl
           interpreters have been fixed [perl #77352]

       o   A possible string corruption when doing regular expression matches
           on overloaded objects has been fixed [perl #77084]

       o   Magic applied to variables in the main package no longer affects
           other packages.  See "Magic variables outside the main package"
           above [perl #76138]

       o   Opening a glob reference via "open $fh, ">", \*glob" will no longer
           cause the glob to be corrupted when the filehandle is printed to.
           This would cause perl to crash whenever the glob's contents were
           accessed [perl #77492]

       o   The postincrement and postdecrement operators, "++" and "--", used
           to cause leaks when being used on references.  This has now been

       o   A bug when replacing the glob of a loop variable within the loop

           These functions now call "SvROK" on their arguments before
           dereferencing them with "SvRV", and we test for this case in

       o   When assigning a list with duplicated keys to a hash, the
           assignment used to return garbage and/or freed values:

               @a = %h = (list with some duplicate keys);

           This has now been fixed [perl #31865]

       o   An earlier release of the 5.13 series of Perl changed the semantics
           of opening a reference to a copy of a glob:

               my $var = *STDOUT;
               open my $fh, '>', \$var;

           This was a mistake, and the previous behaviour from Perl 5.10 and
           5.12, which is to treat \$var as a scalar reference, has now been

       o   The regular expression bracketed character class "[\8\9]" was
           effectively the same as "[89\000]", incorrectly matching a NULL
           character.  It also gave incorrect warnings that the 8 and 9 were
           ignored.  Now "[\8\9]" is the same as "[89]" and gives legitimate
           warnings that "\8" and "\9" are unrecognized escape sequences,

       o   "warn()" and "die()" now respect utf8-encoded scalars [perl #45549]

Known Problems
       o   The upgrade to Encode-2.40 has caused some tests in the libwww-perl
           distribution on CPAN to fail. (Specifically, base/message-charset.t
           tests 33-36 in version 5.836 of that distribution now fail.)

       o   The upgrade to ExtUtils-MakeMaker-6.57_05 has caused some tests in
           the Module-Install distribution on CPAN to fail. (Specifically,
           02_mymeta.t tests 5 and 21, 18_all_from.t tests 6 and 15,
           19_authors.t tests 5, 13, 21 and 29, and
           20_authors_with_special_characters.t tests 6, 15 and 23 in version
           1.00 of that distribution now fail.)

       Perl 5.13.5 represents approximately one month of development since
       Perl 5.13.4 and contains 74558 lines of changes across 549 files from
       45 authors and committers:

       Abigail, Alexander Alekseev, Aristotle Pagaltzis, Ben Morrow, Bram,
       brian d foy, Chas. Owens, Chris 'BinGOs' Williams, Craig A. Berry,
       Curtis Jewell, Dagfinn Ilmari Mannsaaker, David Golden, David
       Leadbeater, David Mitchell, Eric Brine, Father Chrysostomos, Florian

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 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 v5.14.2                      2011-09-26                  PERL5135DELTA(1)
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