regcomp.c: Clarify comment

[perl5.git] / pod / perldelta.pod

=encoding utf8

=head1 NAME

[ this is a template for a new perldelta file. Any text flagged as
XXX needs to be processed before release. ]

perldelta - what is new for perl v5.13.9

=head1 DESCRIPTION

This document describes differences between the 5.13.8 release and
the 5.13.9 release.

If you are upgrading from an earlier release such as 5.13.7, first read
L<perl5138delta>, which describes differences between 5.13.7 and
5.13.8.

=head1 Notice

XXX Any important notices here

=head1 Core Enhancements

XXX New core language features go here. Summarise user-visible core language
enhancements. Particularly prominent performance optimisations could go
here, but most should go in the L</Performance Enhancements> section.

With this release, Perl is adopting a model that any unsigned value can
be encoded internally as utf8 without warnings -- not just the ones that
are legal in Unicode.
However, unless UTF8 warnings have been
explicitly lexically turned off, outputting or performing a
Unicode-defined operation (such as upper-casing) on such a code point
will generate a warning.  Attempting to input these using strict rules
(such as with the C<:encoding('UTF-8')> layer) will continue to fail.
Prior to this release the handling was very inconsistent, and incorrect
in places.  Also, the Unicode non-characters, some of which previously were
erroneously considered illegal in places by Perl, contrary to the Unicode
standard, are now always legal internally.  But inputting or outputting
them will work the same as for the non-legal Unicode code points, as the
Unicode standard says they are illegal for "open interchange".

[ List each enhancement as a =head2 entry ]

=head1 Security

XXX Any security-related notices go here.  In particular, any security
vulnerabilities closed should be noted here rather than in the
L</Selected Bug Fixes> section.

[ List each security issue as a =head2 entry ]

=head1 Incompatible Changes

XXX For a release on a stable branch, this section aspires to be:

    There are no changes intentionally incompatible with 5.XXX.XXX. If any
    exist, they are bugs and reports are welcome.

[ List each incompatible change as a =head2 entry ]

=head1 Deprecations

XXX Any deprecated features, syntax, modules etc. should be listed here.
In particular, deprecated modules should be listed here even if they are
listed as an updated module in the L</Modules and Pragmata> section.

[ List each deprecation as a =head2 entry ]

=head1 Performance Enhancements

XXX Changes which enhance performance without changing behaviour go here. There
may well be none in a stable release.

[ List each enhancement as a =item entry ]

=over 4

=item *

XXX

=back

=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<CPAN::Meta::YAML> 0.002 has been added as a dual-life module.  It supports a
subset of YAML sufficient for reading and writing META.yml and MYMETA.yml files
included with CPAN distributions or generated by the module installation
toolchain. It should not be used for any other general YAML parsing or
generation task.

=item *

L<HTTP::Tiny> 0.008 has been added as a dual-life module.  It is a very
small, simple HTTP/1.1 client designed for simple GET requests and file
mirroring.  It has has been added to enable CPAN.pm and CPANPLUS to
"bootstrap" HTTP access to CPAN using pure Perl without relying on external
binaries like F<curl> or F<wget>.

=item *

L<Module::Metadata> 1.000003 has been added as a dual-life module.  It gathers
package and POD information from Perl module files.  It is a standalone module
based on Module::Build::ModuleInfo for use by other module installation
toolchain components.  Module::Build::ModuleInfo has been deprecated in
favor of this module instead.

=item *

L<Perl::OSType> 1.002 has been added as a dual-life module.  It maps Perl
operating system names (e.g. 'dragonfly' or 'MSWin32') to more generic types
with standardized names (e.g.  "Unix" or "Windows").  It has been refactored
out of Module::Build and ExtUtils::CBuilder and consolidates such mappings into
a single location for easier maintenance.

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

C<Archive::Extract> has been upgraded from version 0.46 to 0.48

=item *

C<Archive::Tar> has been upgraded from version 1.74 to 1.76

=item *

C<CGI> has been upgraded from version 3.50 to 3.51

=item *

C<Compress::Raw::Bzip2> has been upgraded from version 2.031 to 2.033

=item *

C<Compress::Raw::Zlib> has been upgraded from version 2.030 to 2.033

=item *

C<CPANPLUS> has been upgraded from version 0.9010 to 0.9011

=item *

C<CPANPLUS::Dist::Build> has been upgraded from version 0.50 to 0.52

=item *

C<DB_File> has been upgraded from version 1.820 to 1.821

=item *

C<Encode> has been upgraded from version 2.40 to 2.42.
Now, all 66 Unicode non-characters are treated the same way U+FFFF has
always been treated; if it was disallowed, all 66 are disallowed; if it
warned, all 66 warn.

=item *

C<File::Fetch> has been upgraded from version 0.28 to 0.30

=item *

C<IO::Compress> has been upgraded from version 2.030 to 2.033

=item *

C<IPC::Cmd> has been upgraded from version 0.66 to 0.68

=item *

C<Log::Message> has been upgraded from version 0.02 to 0.04

=item *

C<Module::Load::Conditional> has been upgraded from version 0.38 to 0.40

=item *

C<Object::Accessor> has been upgraded from version 0.36 to 0.38

=item *

C<Params::Check> has been upgraded from version 0.26 to 0.28

=item *

C<Pod::LaTeX> has been upgraded from version 0.58 to 0.59

=item *

C<Term::UI> has been upgraded from version 0.20 to 0.24

=item *

C<threads> has been upgraded from version 1.81_03 to 1.82

=item *

C<threads::shared> has been upgraded from version 1.35 to 1.36

=item *

C<Time::Local> has been upgraded from version 1.1901_01 to 1.2000.

=item *

C<Unicode::Collate> has been upgraded from version 0.68 to 0.70

This also sees the switch from using the pure-perl version of this
module to the XS version.

=item *

C<Unicode::Normalize> has been upgraded from version 1.07 to 1.10

=back

=head2 Removed Modules and Pragmata

=over 4

=item *

XXX

=back

=head1 Documentation

XXX Changes to files in F<pod/> go here.  Consider grouping entries by
file and be sure to link to the appropriate page, e.g. L<perlfunc>.

=head2 New Documentation

XXX Changes which create B<new> files in F<pod/> go here.

=head3 L<XXX>

XXX Description of the purpose of the new file here

=head2 Changes to Existing Documentation

XXX Changes which significantly change existing files in F<pod/> go here.
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.

=head3 L<XXX>

=over 4

=item *

XXX Description of the change here

=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>.

XXX New or changed warnings emitted by the core's C<C> code go here. Also
include any changes in L<perldiag> that reconcile it to the C<C> code.

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

=head2 New Diagnostics

XXX Newly added diagnostic messages go here

=over 4

=item *

XXX

=back

=head2 Changes to Existing Diagnostics

XXX Changes (i.e. rewording) of diagnostic messages go here

=over 4

=item *

XXX

=back

=head1 Utility Changes

XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
here. Most of these are built within the directories F<utils> and F<x2p>.

[ List utility changes as a =head3 entry for each utility and =item
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]

=head3 L<XXX>

=over 4

=item *

XXX

=back

=head1 Configuration and Compilation

XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
go here.  Any other changes to the Perl build process should be listed here.
However, any platform-specific changes should be listed in the
L</Platform Support> section, instead.

[ List changes as a =item entry ].

=over 4

=item *

XXX

=back

=head1 Testing

XXX Any significant changes to the testing of a freshly built perl should be
listed here.  Changes which create B<new> files in F<t/> go here as do any
large changes to the testing harness (e.g. when parallel testing was added).
Changes to existing files in F<t/> aren't worth summarising, although the bugs
that they represent may be covered elsewhere.

[ List each test improvement as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Platform Support

XXX Any changes to platform support should be listed in the sections below.

[ Within the sections, list each platform as a =item entry with specific
changes as paragraphs below it. ]

=head2 New Platforms

XXX List any platforms that this version of perl compiles on, that previous
versions did not. These will either be enabled by new files in the F<hints/>
directories, or new subdirectories and F<README> files at the top level of the
source tree.

=over 4

=item XXX-some-platform

XXX

=back

=head2 Discontinued Platforms

XXX List any platforms that this version of perl no longer compiles on.

=over 4

=item XXX-some-platform

XXX

=back

=head2 Platform-Specific Notes

XXX List any changes for specific platforms. This could include configuration
and compilation changes or changes in portability/compatibility.  However,
changes within modules for platforms should generally be listed in the
L</Modules and Pragmata> section.

=over 4

=item XXX-some-platform

XXX

=back

=head1 Internal Changes

XXX Changes which affect the interface available to C<XS> code go here.
Other significant internal changes for future core maintainers should
be noted as well.

[ List each test improvement as a =item entry ]

=over 4

=item *

The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp> have
been merged. The implementation functions C<Perl_do_chop()> and
C<Perl_do_chomp()>, never part of the public API, have been merged and moved to
a static function in F<pp.c>. This shrinks the perl binary slightly, and should
not affect any code outside the core (unless it is relying on the order of side
effects when C<chomp> is passed a I<list> of values).

=item *

Some of the flags parameters to the uvuni_to_utf8_flags() and
utf8n_to_uvuni() have changed.  This is a result of Perl now allowing
internal storage and manipulation of code points that are problematic
in some situations.  Hence, the default actions for these functions has
been complemented to allow these code points.  The new flags are
documented in L<perlapi>.  Code that requires the problematic code
points to be rejected needs to change to use these flags.  Some flag
names are retained for backward source compatibility, though they do
nothing, as they are now the default.  However the flags
C<UNICODE_ALLOW_FDD0>, C<UNICODE_ALLOW_FFFF>, C<UNICODE_ILLEGAL>, and
C<UNICODE_IS_ILLEGAL> have been removed, as they stem from a
fundamentally broken model of how the Unicode non-character code points
should be handled, which is now described in
L<perlunicode/Non-character code points>.  See also L</Selected Bug Fixes>.

=item *

Certain shared flags in the C<pmop.op_pmflags> and C<regexp.extflags>
structures have been removed.  These are: C<Rxf_Pmf_LOCALE>,
C<Rxf_Pmf_UNICODE>, and C<PMf_LOCALE>.  Instead there are encodes and
three static in-line functions for accessing the information:
C<get_regex_charset()>, C<set_regex_charset()>, and C<get_regex_charset_name()>,
which are defined in the places where the orginal flags were.

=back

=head1 Selected Bug Fixes

XXX Important bug fixes in the core language are summarised here.
Bug fixes in files in F<ext/> and F<lib/> are best summarised in
L</Modules and Pragmata>.

[ List each fix as a =item entry ]

=over 4

=item *

The handling of Unicode non-characters has changed.
Previously they were mostly considered illegal, except that only one of
the 66 of them was known about in places.  The Unicode standard
considers them legal, but forbids the "open interchange" of them.
This is part of the change to allow the internal use of any code point
(see L</Core Enhancements>).  Together, these changes resolve
L<# 38722|https://rt.perl.org/rt3/Ticket/Display.html?id=38722>,
L<# 51918|http://rt.perl.org/rt3/Ticket/Display.html?id=51918>,
L<# 51936|http://rt.perl.org/rt3/Ticket/Display.html?id=51936>,
L<# 63446|http://rt.perl.org/rt3/Ticket/Display.html?id=63446>

=back

=head1 Known Problems

XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
tests that had to be C<TODO>ed for the release would be noted here, unless
they were specific to a particular platform (see below).

This is a list of some significant unfixed bugs, which are regressions
from either 5.XXX.XXX or 5.XXX.XXX.

[ List each fix as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Obituary

XXX If any significant core contributor has died, we've added a short obituary
here.

=head1 Acknowledgements

XXX The list of people to thank goes here.

=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 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