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NAME

       perl5135delta - what is new for perl v5.13.5

DESCRIPTION

       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", etc.

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

       This has been fixed (or the feature has been removed, depending on how you see it).

   Smart-matching against array slices
       Previously, the following code resulted in a successful match:

           my @a = qw(a y0 z);
           my @b = qw(a x0 z);
           @a[0 .. $#b] ~~ @b;

       This odd behaviour has now been fixed [perl #77468]
       <http://rt.perl.org/rt3//Public/Bug/Display.html?id=77468>.

   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.)

Deprecations

   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

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

       ·   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
       "bignum"
           Upgraded from version 0.23 to 0.25.

       "blib"
           Upgraded from version 1.05 to 1.06.

       "open"
           Upgraded from version 1.07 to 1.08.

       "threads-shared"
           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 respectively.

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

       "B::Debug"
           Upgraded from version 1.12 to 1.16.

       "CPANPLUS::Dist::Build"
           Upgraded from version 0.46 to 0.48.

       "Data::Dumper"
           Upgraded from version 2.126 to 2.128.

           This fixes a crash when using custom sort functions that might cause the stack to
           change.

       "Encode"
           Upgraded from version 2.39 to 2.40.

       "Errno"
           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]
           <http://rt.perl.org/rt3//Public/Bug/Display.html?id=77416>.

       "ExtUtils::MakeMaker"
           Upgraded from version 6.5601 to 6.57_05.

       "Filter::Simple"
           Upgraded from version 0.84 to 0.85.

       "Hash::Util"
           Upgraded from version 0.08 to 0.09.

       "Math::BigInt"
           Upgraded from version 1.89_01 to 1.95.

           This fixes, among other things, incorrect results when computing binomial coefficients
           [perl #77640] <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77640>.

       "Math::BigInt::FastCalc"
           Upgraded from version 0.19 to 0.22.

       "Math::BigRat"
           Upgraded from version 0.24 to 0.26.

       "Module::CoreList"
           Upgraded from version 2.37 to 2.38.

       "PerlIO::scalar"
           Upgraded from version 0.08 to 0.09.

       "POSIX"
           Upgraded from version 1.19 to 1.20.

           It now includes constants for POSIX signal constants.

       "Safe"
           Upgraded from version 2.27 to 2.28.

           This fixes a possible infinite loop when looking for coderefs.

       "Test::Simple"
           Upgraded from version 0.96 to 0.97_01.

       "Tie::Hash"
           Upgraded from version 1.03 to 1.04.

           Calling "Tie::Hash->TIEHASH()" used to loop forever.  Now it "croak"s.

       "Unicode::Collate"
           Upgraded from version 0.56 to 0.59.

       "XSLoader"
           Upgraded from version 0.10 to 0.11.

Documentation

   Changes to Existing Documentation
       perlapi

       ·   Many of the optree construction functions are now documented.

       perlbook

       ·   Expanded to cover many more popular books.

       perlfaq

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

Diagnostics

       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
       ·   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.

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

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

   Changes to Existing Diagnostics
       ·   "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

       h2ph

       ·   The use of a deprecated "goto" construct has been removed [perl #74404]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=74404>.

Testing

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

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

       ·   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
       VMS
           ·   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 from Perl became "PerlIOUnix_open", which has
               always explicitly used 0666 as the permission mask.

               To avoid this, 0777 is now passed as the permissions to "open()".  In the VMS
               CRTL, 0777 has a special meaning over and above intersecting with the current
               umask; specifically, it allows Unix syscalls to preserve native default
               permissions.

Internal Changes

       ·   "CALL_FPTR" and "CPERLscope" have been deprecated.

           Those are left from an old implementation of "MULTIPLICITY" using 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.

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

       ·   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

       ·   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".

       ·   A fatal error in regular expressions when processing UTF-8 data has been fixed [perl
           #75680] <http://rt.perl.org/rt3/Public/Bug/Display.html?id=75680>.

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

       ·   The Perl debugger now also works in taint mode [perl #76872]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=76872>.

       ·   Several memory leaks in cloning and freeing threaded Perl interpreters have been fixed
           [perl #77352] <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77352>.

       ·   A possible string corruption when doing regular expression matches on overloaded
           objects has been fixed [perl #77084]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77084>.

       ·   Magic applied to variables in the main package no longer affects other packages.  See
           "Magic variables outside the main package" above [perl #76138]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=76138>.

       ·   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]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77492>.

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

       ·   A bug when replacing the glob of a loop variable within the loop has been fixed [perl
           #21469] <http://rt.perl.org/rt3/Public/Bug/Display.html?id=21469>.  This means the
           following code will no longer crash:

               for $x (...) {
                   *x = *y;
               }

       ·   Perl would segfault if the undocumented "Internals" functions that used reference
           prototypes were called with the "&foo()" syntax, e.g.  "&Internals::SvREADONLY(undef)"
           [perl #77776] <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77776>.

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

       ·   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]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=31865>.

       ·   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 restored.

       ·   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, passed-
           through.

       ·   "warn()" and "die()" now respect utf8-encoded scalars [perl #45549]
           <http://rt.perl.org/rt3/Public/Bug/Display.html?id=45549>.

Known Problems

       ·   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.)

       ·   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.)

Acknowledgements

       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
       Ragwitz, Gisle Aas, Jan Dubois, Jerry D. Hedden, Jesse Vincent, Jim Cromie, Jirka HruXka,
       Karl Williamson, Michael G. Schwern, Nicholas Clark, Paul Johnson, Philippe Bruhat (BooK),
       Piotr Fusik, Rafael Garcia-Suarez, Rainer Tammer, Reini Urban, Ricardo Signes, Rob Hoelz,
       Robin Barker, Steffen Mueller, Steve Hay, Steve Peters, Todd Rinaldo, Tony Cook, Vincent
       Pit, Yves Orton, Zefram, Zsban Ambrus, var Arnfjoer` Bjarmason.

       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.

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@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@perl.org.  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.

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.