=encoding utf8

=head1 NAME

perl52110delta - what is new for perl v5.21.10

=head1 DESCRIPTION

This document describes differences between the 5.21.9 release and the 5.21.10
release.

If you are upgrading from an earlier release such as 5.21.8, first read
L<perl5219delta>, which describes differences between 5.21.8 and 5.21.9.

=head1 Incompatible Changes

=head2 C<(?[...])> operators now follow standard Perl precedence

This experimental feature allows set operations in regular expression patterns.
Prior to this, the intersection operator had the same precedence as the other
binary operators.  Now it has higher precedence.  This could lead to different
outcomes than existing code expects (though the documentation has always noted
that this change might happen, recommending fully parenthesizing the
expressions).  See L<perlrecharclass/Extended Bracketed Character Classes>.

=head1 Performance Enhancements

=over 4

=item *

The functions C<utf8::native_to_unicode()> and C<utf8::unicode_to_native()>
(see L<utf8>) are now optimized out on ASCII platforms.  There is now not even
a minimal performance hit in writing code portable between ASCII and EBCDIC
platforms.

=back

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<B> has been upgraded from version 1.56 to 1.57.

=item *

L<B::Deparse> has been upgraded from version 1.33 to 1.34.

Deparse C<$#_> as that instead of as C<$#{_}>.
L<[perl #123947]|https://rt.perl.org/Ticket/Display.html?id=123947>

=item *

L<Carp> has been upgraded from version 1.35 to 1.36.

=item *

L<CPAN> has been upgraded from version 2.05 to 2.10.

=over 4

=item *

Add support for C<Cwd::getdcwd()> and introduce workaround for a misbehaviour
seen on Strawberry Perl 5.20.1.

=item *

Fix C<chdir()> after building dependencies bug.

=item *

Introduce experimental support for plugins/hooks.

=item *

Integrate the App::Cpan sources.

=item *

Do not check recursion on optional dependencies.

=item *

Sanity check META.yml to contain a hash.
L<[cpan #95271]|https://rt.cpan.org/Ticket/Display.html?id=95271>

=back

=item *

L<CPAN::Meta> has been upgraded from version 2.143240 to 2.150001.

=item *

L<Data::Dumper> has been upgraded from version 2.157 to 2.158.

=item *

L<DB> has been upgraded from version 1.07 to 1.08.

=item *

L<Devel::PPPort> has been upgraded from version 3.28 to 3.31.

=item *

L<DynaLoader> has been upgraded from version 1.31 to 1.32.

=item *

L<Encode> has been upgraded from version 2.70 to 2.72.

=item *

L<encoding> has been upgraded from version 2.13 to 2.14.

=item *

L<Getopt::Long> has been upgraded from version 2.43 to 2.45.

=item *

L<locale> has been upgraded from version 1.05 to 1.06.

=item *

L<Locale::Codes> has been upgraded from version 3.33 to 3.34.

=item *

L<Module::CoreList> has been upgraded from version 5.20150220 to 5.20150320.

=item *

L<parent> has been upgraded from version 0.228 to 0.232.

No changes to installed files other than the version bump.

=item *

The PathTools modules have been upgraded from version 3.54 to 3.55.

=item *

L<Pod::Functions> has been upgraded from version 1.08 to 1.09.

=item *

L<POSIX> has been upgraded from version 1.51 to 1.52.

=item *

L<re> has been upgraded from version 0.31 to 0.32.

=item *

L<sigtrap> has been upgraded from version 1.07 to 1.08.

=item *

L<Term::Complete> has been upgraded from version 1.402 to 1.403.

=item *

L<Test::Simple> has been reverted from version 1.301001_098 to 1.001014.

=item *

L<Text::Balanced> has been upgraded from version 2.02 to 2.03.

No changes to installed files other than the version bump.

=item *

L<Text::ParseWords> has been upgraded from version 3.29 to 3.30.

=item *

L<threads> has been upgraded from version 1.96_001 to 2.01.

=item *

L<Unicode::Collate> has been upgraded from version 1.11 to 1.12.

=item *

L<utf8> has been upgraded from version 1.14 to 1.15.

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=head3 L<perldata>

=over 4

=item *

Documentation has been added regarding the special floating point values C<Inf>
and C<NaN>.

=back

=head3 L<perlexperiment>

=over 4

=item *

Removed note about C<\s> matching C<VT> now that it is no longer experimental.

=item *

Added note that C<use re 'strict'> has been introduced experimentally.

=back

=head3 L<perlpolicy>

=over 4

=item *

The documentation of what to expect to see in future maintenance releases has
been updated.  Essentially the same types of changes will be included as before
but with fewer changes that don't affect the installation or execution of perl.

=back

=head1 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 L<perldiag>.

=head2 New Diagnostics

=head3 New Errors

=over 4

=item *

L<Invalid quantifier in {,} in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/">

(F) The pattern looks like a {min,max} quantifier, but the min or max could not
be parsed as a valid number - either it has leading zeroes, or it represents
too big a number to cope with.  The S<<-- HERE> shows where in the regular
expression the problem was discovered.  See L<perlre>.

=back

=head1 Testing

=over 4

=item *

Tests for performance issues have been added in the file F<t/perf/taint.t>.

=back

=head1 Platform Support

=head2 New Platforms

=over 4

=item z/OS running EBCDIC Code Page 1047

Core perl now works on this EBCDIC platform.  Early perls also worked, but,
even though support wasn't officially withdrawn, recent perls would not compile
and run well.  Perl 5.20 would work, but had many bugs which have now been
fixed.  Many CPAN modules that ship with Perl still fail tests, including
Pod::Simple.  However the version of Pod::Simple currently on CPAN should work;
it was fixed too late to include in Perl 5.22.  Work is under way to fix many
of the still-broken CPAN modules, which likely will be installed on CPAN when
completed, so that you may not have to wait until Perl 5.24 to get a working
version.

=back

=head2 Platform-Specific Notes

=over 4

=item HP-UX

The archname now distinguishes use64bitint from use64bitall.

=back

=head1 Internal Changes

=over 4

=item *

Macros have been created to allow XS code to better manipulate the POSIX locale
category C<LC_NUMERIC>.  See L<perlapi/Locale-related functions and macros>.

=item *

The previous C<atoi> et al replacement function, C<grok_atou>, has now been
superseded by C<grok_atoUV>.  See L<perlclib> for details.

=back

=head1 Selected Bug Fixes

=over 4

=item *

Repeated global pattern matches in scalar context on large tainted strings were
exponentially slow depending on the current match position in the string.
L<[perl #123202]|https://rt.perl.org/Ticket/Display.html?id=123202>

=item *

Various crashes due to the parser getting confused by syntax errors have been
fixed.
L<[perl #123801]|https://rt.perl.org/Ticket/Display.html?id=123801>
L<[perl #123802]|https://rt.perl.org/Ticket/Display.html?id=123802>
L<[perl #123955]|https://rt.perl.org/Ticket/Display.html?id=123955>
L<[perl #123995]|https://rt.perl.org/Ticket/Display.html?id=123995>

=item *

C<split> in the scope of lexical $_ has been fixed not to fail assertions.
L<[perl #123763]|https://rt.perl.org/Ticket/Display.html?id=123763>

=item *

C<my $x : attr> syntax inside various list operators no longer fails
assertions.
L<[perl #123817]|https://rt.perl.org/Ticket/Display.html?id=123817>

=item *

An @ sign in quotes followed by a non-ASCII digit (which is not a valid
identifier) would cause the parser to crash, instead of simply trying the @ as
literal.  This has been fixed.
L<[perl #123963]|https://rt.perl.org/Ticket/Display.html?id=123963>

=item *

C<*bar::=*foo::=*glob_with_hash> has been crashing since Perl 5.14, but no
longer does.
L<[perl #123847]|https://rt.perl.org/Ticket/Display.html?id=123847>

=item *

C<foreach> in scalar context was not pushing an item on to the stack, resulting
in bugs.  (C<print 4, scalar do { foreach(@x){} } + 1> would print 5.)  It has
been fixed to return C<undef>.
L<[perl #124004]|https://rt.perl.org/Ticket/Display.html?id=124004>

=item *

A memory leak introduced in Perl 5.21.6 has been fixed.
L<[perl #123922]|https://rt.perl.org/Ticket/Display.html?id=123922>

=item *

A regression in the behaviour of the C<readline> built-in function, caused by
the introduction of the C<< <<>> >> operator, has been fixed.
L<[perl #123990]|https://rt.perl.org/Ticket/Display.html?id=123990>

=item *

Several cases of data used to store environment variable contents in core C
code being potentially overwritten before being used have been fixed.
L<[perl #123748]|https://rt.perl.org/Ticket/Display.html?id=123748>

=back

=head1 Known Problems

=over 4

=item *

A goal is for Perl to be able to be recompiled to work reasonably well on any
Unicode version.  In Perl 5.22, though, the earliest such version is Unicode
5.1 (current is 7.0).

=item *

EBCDIC platforms

=over 4

=item *

Encode and encoding are mostly broken.

=item *

Many cpan modules that are shipped with core show failing tests.

=item *

C<pack>/C<unpack> with C<"U0"> format may not work properly.

=back

=back

=head1 Acknowledgements

Perl 5.21.10 represents approximately 4 weeks of development since Perl 5.21.9
and contains approximately 170,000 lines of changes across 860 files from 27
authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 170,000 lines of changes to 610 .pm, .t, .c and .h files.

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 5.21.10:

Chris 'BinGOs' Williams, David Golden, David Mitchell, David Wheeler, Father
Chrysostomos, H.Merijn Brand, Hugo van der Sanden, James E Keenan, Jarkko
Hietaniemi, Jasmine Ngan, Jerry D. Hedden, John Goodyear, Karen Etheridge, Karl
Williamson, Lukas Mai, Matthew Horsfall, Nicholas Clark, Petr Písař, Rafael
Garcia-Suarez, Reini Urban, Ricardo Signes, Sawyer X, Steffen Müller, Steve
Hay, Sullivan Beck, Tony Cook, Vincent Pit.

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 F<AUTHORS> file in the Perl source distribution.

=head1 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
https://rt.perl.org/ .  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 L<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 C<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 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.

=head1 SEE ALSO

The F<Changes> file for an explanation of how to view exhaustive details on
what changed.

The F<INSTALL> file for how to build Perl.

The F<README> file for general stuff.

The F<Artistic> and F<Copying> files for copyright information.

=cut
