PERL51311DELTA(1) Perl Programmers Reference Guide PERL51311DELTA(1)NAMEperl51311delta - what is new for perl v5.13.11
DESCRIPTION
This document describes differences between the 5.13.10 release and the
5.13.11 release.
If you are upgrading from an earlier release such as 5.13.9, first read
perl5139delta, which describes differences between 5.13.9 and 5.13.10.
Security
User-defined regular expression properties
Perl no longer allows a tainted regular expression to invoke a user-
defined property via "\p{...}" syntax. It simply dies instead [perl
#82616].
Incompatible Changes
local($_) will strip all magic from $_
local() on scalar variables will give them a new value, but keep all
their magic intact. This has proven to be problematic for the default
scalar variable $_, where perlsub recommends that any subroutine that
assigns to $_ should localize it first. This would throw an exception
if $_ is aliased to a read-only variable, and could have various
unintentional side-effects in general.
Therefore, as an exception to the general rule, local($_) will not only
assign a new value to $_, but also remove all existing magic from it as
well.
Passing references to warn()
An earlier Perl 5.13.x release changed "warn($ref)" to leave the
reference unchanged, allowing $SIG{__WARN__} handlers to access the
original reference. But this stopped warnings that were references from
having the file and line number appended even when there was no
$SIG{__WARN__} handler in place.
Now "warn" checks for the presence of such a handler and, if there is
none, proceeds to stringify the reference and append the file and line
number. This allows simple uses of "warn" for debugging to continue to
work as they did before.
fork() emulation will not wait for signalled children
On Windows parent processes would not terminate until all forked
childred had terminated first. However, "kill('KILL', ...)" is
inherently unstable on pseudo-processes, and "kill('TERM', ...)" might
not get delivered if the child if blocked in a system call.
To avoid the deadlock and still provide a safe mechanism to terminate
the hosting process, Perl will now no longer wait for children that
have been sent a SIGTERM signal. It is up to the parent process to
waitpid() for these children if child clean-up processing must be
allowed to finish. However, it is also the responsibility of the parent
then to avoid the deadlock by making sure the child process can't be
blocked on I/O either.
See perlfork for more information about the fork() emulation on
Windows.
Perl source code is read in text mode on Windows
Perl scripts used to be read in binary mode on Windows for the benefit
of the ByteLoader module (which is no longer part of core Perl). This
had the side effect of breaking various operations on the DATA
filehandle, including seek()/tell(), and even simply reading from DATA
after file handles have been flushed by a call to system(), backticks,
fork() etc.
The default build options for Windows have been changed to read Perl
source code on Windows in text mode now. Hopefully ByteLoader will be
updated on CPAN to automatically handle this situation.
Performance Enhancements
· An earlier optimisation to speed up "my @array = ..." and "my %hash
= ..." assignments caused a bug and was disabled in Perl 5.12.0.
Now we have found another way to speed up these assignments [perl
#82110].
Modules and Pragmata
Updated Modules and Pragmata
· "attributes" has been upgraded from version 0.13 to 0.14.
· "base" has been upgraded from version 2.15 to 2.16.
· "CPAN" has been upgraded from version 1.94_65 to 1.9600.
· "CPANPLUS" has been upgraded from version 0.9101 to 0.9103
· "CPANPLUS::Dist::Build" has been upgraded from version 0.52 to 0.54
· "Cwd" has been downgraded from version 3.37 to 3.36.
An optimisation that recent core changes have rendered unnecessary
has been reverted.
· "Devel::DProf" has been upgraded from version 20110225.01 to
20110228.00.
· "Digest::SHA" has been upgraded from version 5.50 to 5.61
New SHA-512/224 and SHA-512/256 transforms ref. NIST Draft FIPS
180-4 (February 2011)
· "ExtUtils::Command" has been upgraded from version 1.16 to 1.17.
· "File::Copy" has been downgraded from version 2.22 to 2.21.
An optimisation that recent core changes have rendered unnecessary
has been reverted.
· "File::Glob" has been upgraded from version 1.11 to 1.12.
· "GDBM_File" has been upgraded from version 1.13 to 1.14.
· "Hash::Util" has been upgraded from version 0.10 to 0.11.
· "Hash::Util::FieldHash" has been upgraded from version 1.08 to
1.09.
· "HTTP::Tiny" has been upgraded from version 0.010 to 0.011.
· "I18N::Langinfo" has been upgraded from version 0.07 to 0.08.
· "IO" has been upgraded from version 1.25_03 to 1.25_04.
· "JSON::PP" has been upgraded from version 2.27103 to 2.27105
· "Locale::Codes" has been upgraded from version 3.15 to 3.16
· "Math::BigInt" has been upgraded from version 1.992 to 1.994
· "Math::BigInt::FastCalc" has been upgraded from version 0.24_02 to
0.28
· "Module::Build" has been upgraded from version 0.37_05 to 0.3800
· "Module::CoreList" has been upgraded from version 2.45 to 2.46.
· "mro" has been upgraded from version 1.06 to 1.07.
· "NDBM_File" has been upgraded from version 1.11 to 1.12.
· "parent" has been upgraded from version 0.224 to 0.225
· "Pod::Simple" has been upgraded from version 3.15 to 3.16
· "Storable" has been upgraded from version 2.26 to 2.27.
· "Sys::Hostname" has been upgraded from version 1.15 to 1.16.
· "Test::Harness" has been upgraded from version 3.22 to 3.23
· "Test::Simple" has been upgraded from version 0.97_01 to 0.98
· "Tie::Hash::NamedCapture" has been upgraded from version 0.07 to
0.08.
Some of the Perl code has been converted to XS for efficency's
sake.
· "Tie::RefHash" has been upgraded from version 1.38 to 1.39.
· "Unicode::Collate" has been upgraded from version 0.72 to 0.73
DUCET has been updated for Unicode 6.0.0 as Collate/allkeys.txt and
the default UCA_Version is 22.
· "Unicode::UCD" has been upgraded from version 0.31 to 0.32. This
includes a number of bug fixes:
charinfo()
· It is now updated to Unicode Version 6 with Corrigendum #8,
except, as with Perl 5.14, the code point at U+1F514 has no
name.
· The Hangul syllable code points have the correct names, and
their decompositions are always output without requiring
Lingua::KO::Hangul::Util to be installed.
· The CJK (Chinese-Japanese-Korean) code points U+2A700 -
U+2B734 and U+2B740 - 2B81D are now properly handled.
· The numeric values are now output for those CJK code points
that have them.
· The names that are output for code points with multiple
aliases are now the corrected ones.
charscript()
This now correctly returns "Unknown" instead of "undef" for the
script of a code point that hasn't been assigned another one.
charblock()
This now correctly returns "No_Block" instead of "undef" for
the block of a code point that hasn't been assigned to another
one.
· "XS::Typemap" has been upgraded from version 0.04 to 0.05.
Documentation
Changes to Existing Documentation
perlfunc
· Clarified the order in which to check $@ and $! after "do FILE".
(RT #80626)
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
· Regexp modifier "/%c" may not appear twice
(F syntax) The regular expression pattern had one of the mutually
exclusive modifiers repeated. Remove all but one of the
occurrences.
· Regexp modifiers "/%c" and "/%c" are mutually exclusive
(F syntax) The regular expression pattern had more than one of the
mutually exclusive modifiers. Retain only the modifier that is
supposed to be there.
· Insecure user-defined property %s
(F) Perl detected tainted data when trying to compile a regular
expression that contains a call to a user-defined character
property function, i.e. "\p{IsFoo}" or "\p{InFoo}". See "User-
Defined Character Properties" in perlunicode and perlsec.
Testing
Many of the tests have been refactored to use testing libraries more
consistently. In some cases test files were created or deleted:
· The tests for "split /\s/" and Unicode have been moved from
t/op/split.t to the new t/op/split_unicode.t.
· t/re/re.t has been moved to ext/re/t/re_funcs_u.t.
· The tests for [perl #72922] have been moved from t/re/qr.t to the
new t/re/qr-72922.t.
· t/re/reg_unsafe.t has been deleted and its only test moved to
t/re/pat_advanced.t.
Selected Bug Fixes
· A fix for a bug in "length(undef)" in 5.13.4 introduced a
regression that meant "print length undef" did not warn when
warnings were enabled. It now correctly warns [perl #85508].
· The "(?|...)" regular expression construct no longer crashes if the
final branch has more sets of capturing parentheses than any other
branch. This was fixed in Perl 5.10.1 for the case of a single
branch, but that fix did not take multiple branches into account
[perl #84746].
· Accessing an element of a package array with a hard-coded number
(as opposed to an arbitrary expression) would crash if the array
did not exist. Usually the array would be autovivified during
compilation, but typeglob manipulation could remove it, as in these
two cases which used to crash:
*d = *a; print $d[0];
undef *d; print $d[0];
· "#line" directives in string evals were not properly updating the
arrays of lines of code ("@{"_<..."}") that the debugger (or any
debugging or profiling module) uses. In threaded builds, they were
not being updated at all. In non-threaded builds, the line number
was ignored, so any change to the existing line number would cause
the lines to be misnumbered [perl #79442].
· $AUTOLOAD used to remain tainted forever if it ever became tainted.
Now it is correctly untainted if an autoloaded method is called and
the method name was not tainted.
· A bug has been fixed in the implementation of "{...}" quantifiers
in regular expressions that prevented the code block in "/((\w+)(?{
print $2 })){2}/" from seeing the $2 sometimes [perl #84294].
· "sprintf" now dies when passed a tainted scalar for the format. It
did already die for arbitrary expressions, but not for simple
scalars [perl #82250].
· DESTROY methods of objects implementing ties are no longer able to
crash by accessing the tied variable through a weak reference [perl
#86328].
· On Windows, calling kill(9, $child) on a pseudo-process created by
the fork() emulation is inherently unstable. It can also be
responsible for overriding the parent process exit code with a
value of '9' if the parent terminates right after killing the
child. This condition will now happen a lot less often than
before.
See also "fork() emulation will not wait for signalled children"
for a better way to terminate child processes that avoids deadlocks
altogether.
· Ensure that the "exists &Errno::EFOO" idiom continues to work as
documented.
A change post-5.12 caused the documented idiom not to work if Errno
was loaded after the "exists" code had been compiled, as the
compiler implicitly creates typeglobs in the Errno symbol table
when it builds the optree for the "exists code".
Acknowledgements
Perl 5.13.11 represents approximately one month of development since
Perl 5.13.10 and contains approximately 80,000 lines of changes across
549 files from 31 authors and committers:
Alastair Douglas, Arvan, Boris Ratner, brian d foy, Chris 'BinGOs'
Williams, Craig A. Berry, David Golden, David Leadbeater, David
Mitchell, Father Chrysostomos, Florian Ragwitz, Jan Dubois, Karl
Williamson, Kevin Ryde, Leon Brocard, Leon Timmermans, Michael Stevens,
Michael Witten, Moritz Lenz, Nicholas Clark, Paul Johnson, Peter John
Acklam, Reini Urban, Robin Barker, Steve Hay, Sullivan Beck, Tony Cook,
Vadim Konovalov, Yves Orton, Zefram and var Arnfjoer` Bjarmason
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 v5.14.4 2012-12-19 PERL51311DELTA(1)
