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=encoding utf8

=head1 NAME

perldelta - what is new for perl v5.17.9

=head1 DESCRIPTION

This document describes differences between the 5.17.8 release and the 5.17.9
release.

If you are upgrading from an earlier release such as 5.17.7, first read
L<perl5178delta>, which describes differences between 5.17.7 and 5.17.8.

=head1 Core Enhancements

=head2 Interpolations now Accepted in Regular Expression Set Operations

Perl v5.17.8 introduced L<regular expression set operations|perlre/(?[ ])>.
They have now been expanded to allow the interpolation of a
previously-compiled set into a bigger set, like this:

 my $thai_or_lao = qr/\p{Thai} + \p{Lao}/;
 ...
 qr/(?[ \p{Digit} & $thai_or_lao ])/;

=head1 Incompatible Changes

=head2 C<$ENV{foo} = undef> no longer deletes value from environ

5.17.3 Introduced a change where assiging C<undef> to an C<%ENV> key was equivalent
to C<delete $ENV{foo}>.

This release reverts that change.

=head1 Deprecations

The deprecation of lexical C<$_> in 5.17.7 has been commuted.  The feature
is now marked experimental.

=head2 Deprecated pragma

=over

=item L<encoding>

This module is deprecated under perl 5.18.  It uses a mechanism provided by
perl that is deprecated under 5.18 and higher, and may be removed in a
future version.

=back

=head2 Deprecated Modules

The following modules will be removed from the core distribution in a
future release, and should be installed from CPAN instead. Distributions
on CPAN which require these should add them to their prerequisites. The
core versions of these modules C<warnings> will issue a deprecation warning.

You can silence these deprecation warnings by installing the modules
in question from CPAN.

=over

=item L<Archive::Extract>

=item L<B::Lint>

=item L<B::Lint::Debug>

=item L<CPANPLUS>

=item L<CPANPLUS::Backend>

=item L<CPANPLUS::Backend::RV>

=item L<CPANPLUS::Config>

=item L<CPANPLUS::Config::HomeEnv>

=item L<CPANPLUS::Configure>

=item C<CPANPLUS::Configure::Setup>

=item L<CPANPLUS::Dist>

=item L<CPANPLUS::Dist::Autobundle>

=item L<CPANPLUS::Dist::Base>

=item L<CPANPLUS::Dist::Build>

=item L<CPANPLUS::Dist::Build::Constants>

=item L<CPANPLUS::Dist::MM>

=item L<CPANPLUS::Dist::Sample>

=item L<CPANPLUS::Error>

=item L<CPANPLUS::Internals>

=item C<CPANPLUS::Internals::Constants>

=item C<CPANPLUS::Internals::Constants::Report>

=item L<CPANPLUS::Internals::Extract>

=item L<CPANPLUS::Internals::Fetch>

=item L<CPANPLUS::Internals::Report>

=item L<CPANPLUS::Internals::Search>

=item L<CPANPLUS::Internals::Source>

=item L<CPANPLUS::Internals::Source::Memory>

=item L<CPANPLUS::Internals::Source::SQLite>

=item C<CPANPLUS::Internals::Source::SQLite::Tie>

=item L<CPANPLUS::Internals::Utils>

=item C<CPANPLUS::Internals::Utils::Autoflush>

=item L<CPANPLUS::Module>

=item L<CPANPLUS::Module::Author>

=item L<CPANPLUS::Module::Author::Fake>

=item L<CPANPLUS::Module::Checksums>

=item L<CPANPLUS::Module::Fake>

=item C<CPANPLUS::Module::Signature>

=item L<CPANPLUS::Selfupdate>

=item L<CPANPLUS::Shell>

=item L<CPANPLUS::Shell::Classic>

=item L<CPANPLUS::Shell::Default>

=item L<CPANPLUS::Shell::Default::Plugins::CustomSource>

=item L<CPANPLUS::Shell::Default::Plugins::Remote>

=item L<CPANPLUS::Shell::Default::Plugins::Source>

=item L<Devel::InnerPackage>

=item L<Log::Message>

=item L<Log::Message::Config>

=item L<Log::Message::Handlers>

=item L<Log::Message::Item>

=item L<Log::Message::Simple>

=item L<Module::Pluggable>

=item L<Module::Pluggable::Object>

=item L<Object::Accessor>

=item L<Term::UI>

=item L<Term::UI::History>

=back

=head3 Deprecated Utilities

The following utilities will be removed from the core distribution in a
future release as their associated modules have been deprecated. They
will remain available with the applicable CPAN distribution.

=over

=item L<cpanp>

Included with L<CPANPLUS>.

=item C<cpanp-run-perl>

Included with L<CPANPLUS>.

=item L<cpan2dist>

Included with L<CPANPLUS>.

=item L<pod2latex>

The L<Pod::LaTeX> module was deprecated with 5.17.8.

=back

=head2 Five additional characters should be escaped in patterns with C</x>

When a regular expression pattern is compiled with C</x>, Perl treats 6
characters as white space to ignore, such as SPACE and TAB.  However,
Unicode recommends 11 characters be treated thusly.  In preparation to
conforming with this in a future Perl version, in the meantime, use of
any of the missing characters will raise a deprecation warning, unless
turned off.  The five characters are:
U+0085 NEXT LINE,
U+200E LEFT-TO-RIGHT MARK,
U+200F RIGHT-TO-LEFT MARK,
U+2028 LINE SEPARATOR,
and
U+2029 PARAGRAPH SEPARATOR.

=head1 Modules and Pragmata

XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
go here.  If Module::CoreList is updated, generate an initial draft of the
following sections using F<Porting/corelist-perldelta.pl>, which prints stub
entries to STDOUT.  Results can be pasted in place of the '=head2' entries
below.  A paragraph summary for important changes should then be added by hand.
In an ideal world, dual-life modules would have a F<Changes> file that could be
cribbed.

[ Within each section, list entries as a =item entry ]

=head2 New Modules and Pragmata

=over 4

=item *

L<Config::Perl::V> version 0.16 has been added as a dual-lifed module.
It provides structured data retrieval of C<perl -V> output including
information only known to the C<perl> binary and not available via L<Config>.

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Benchmark> has been upgraded from version 1.13 to 1.14.

The "too few iterations" message is now a warning on STDERR
instead of being output on STDOUT.

=item *

L<Data::Dumper> has been upgraded from version 2.141 to 2.142.

Additional tests were added in order to improve statement, branch, condition
and subroutine coverage.  On the basis of the coverage analysis, some of the
internals of Dumper.pm were refactored.  Almost all methods are now
documented.

=item *

L<File::Temp> has been upgraded from version 0.22 to 0.22_90

Fixes various bugs involving directory removal.  Defers unlinking tempfiles if
the initial unlink fails, which fixes problems on NFS.

=item *

L<PerlIO::scalar> has been upgraded from version 0.15 to 0.16.

The buffer scalar supplied may now only contain code pounts 0xFF or
lower. [perl #109828]

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=head3 L<perlsec>

=over 4

=item *

A syntax error was fixed in one of illustrative examples.

=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 Warnings

=over 4

=item *

Strings with code points over 0xFF may not be mapped into in-memory file handles

=back

=head2 Changes to Existing Diagnostics

=over 4

=item *

The warnings for \b{ and \B{ were added in the 5.17 series; they are a
deprecation warning which should be turned off by that category.  One
should not have to turn off regular regexp warnings as well to get rid
of these.

=back

=head1 Utility Changes

=head3 L<corelist>

=over 4

=item *

Added C<--feature> switch which lists the first version bundle of each
named feature given.

=item *

Added C<--upstream> switch which shows if the given module
is primarily maintained in perl core or on CPAN and bug tracker URL.

=back

=head1 Configuration and Compilation

=over 4

=item *

Added C<useversionedarchname> option to Configure

When set, it includes 'api_versionstring' in 'archname'. E.g.
x86_64-linux-5.13.6-thread-multi.  It is unset by default.

This feature was requested by Tim Bunce, who observed that
INSTALL_BASE creates a library structure that does not
differentiate by perl version.  Instead, it places architecture
specific files in "$install_base/lib/perl5/$archname".  This makes
it difficult to use a common INSTALL_BASE library path with
multiple versions of perl.

By setting -Duseversionedarchname, the $archname will be
distinct for architecture *and* API version, allowing mixed use of
INSTALL_BASE.

=item *

Configure will honour the external C<MAILDOMAIN> environment variable, if set.

=item *

C<installman> no longer ignores the silent option

=item *

Both C<META.yml> and C<META.json> files are now included in the distribution.

=back

=head1 Testing

=over 4

=item *

Enable perl core tests to pass when locale support is not available.

use L<locale> - this will now die if $Config{d_setlocale} is not true.
All tests that use L<locale> will skip if $Config{d_setlocale} is not true.
This enables us to pass tests on Android which uses ICU instead of locales.

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item VMS

The character set for Extended Filename Syntax (EFS) is now enabled by default on
VMS.  Among other things, this provides better handling of dots in directory names,
multiple dots in filenames,and spaces in filenames.  To obtain the old behavior,
set the logical name C<DECC$EFS_CHARSET> to C<DISABLE>.

=item MidnightBSD

C<libc_r> was removed from recent versions of MidnightBSD and older versions
work better with C<pthread>. Threading is now enabled using C<pthread> which
corrects build errors with threading enabled on 0.4-CURRENT.

=back

=head1 Internal Changes

=over 4

=item *

Synonyms for the misleadingly named C<av_len()> has been created:
C<av_top_index()> and C<av_tindex>.  All three of these return the
number of the highest index in the array, not the number of elements it
contains.  (The name C<av_top> which was introduced in Perl v.5.17.8 has
been removed.)

=back

=head1 Selected Bug Fixes

=over 4

=item *

-DPERL_GLOBAL_STRUCT builds now free the global struct B<after>
they've finished using it.

=item *

A trailing '/' on a path in @INC will no longer have an additional '/' appended.

=item *

The C<:crlf> layer now works when unread data doesn't fit into its own
buffer. [perl #112244].

=item *

C<ungetc()> now handles UTF-8 encoded data. [perl #116322].

=back

=head1 Acknowledgements

Perl 5.17.9 represents approximately 4 weeks of development since Perl 5.17.8
and contains approximately 42,000 lines of changes across 510 files from 35
authors.

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 5.17.9:

!, Aaron Crane, Alan Haggai Alavi, Alexandr Ciornii, Andy Dougherty, Brad
Gilbert, Chris 'BinGOs' Williams, Christian Hansen, Craig A. Berry, Dagfinn
Ilmari Mannsåker, Daniel Dragan, Dave Rolsky, David Golden, David Mitchell,
Father Chrysostomos, H.Merijn Brand, James E Keenan, Jan Dubois, Jerry D.
Hedden, Jess Robinson, Karl Williamson, Kent Fredric, Leon Timmermans, Lucas
Holt, Matthew Horsfall, Nicholas Clark, Peter Martini, Rafael Garcia-Suarez,
Ricardo Signes, Smylers, Steffen Müller, Steve Hay, Thomas Sibley, Tobias
Leich, Tony Cook.

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
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 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