PERL5135DELTA(1) Perl Programmers Reference Guide PERL5135DELTA(1)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.
perl v5.14.2 2011-09-26 PERL5135DELTA(1)