perldiag: escape all "<--HERE"

[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 v5.21.11

=head1 DESCRIPTION

This document describes differences between the 5.21.10 release and the 5.21.11
release.

If you are upgrading from an earlier release such as 5.21.9, first read
L<perl52110delta>, which describes differences between 5.21.9 and 5.21.10.

=head1 Notice

XXX Any important notices here

=head1 Core Enhancements

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

[ 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 we request that you submit a
    report.  See L</Reporting Bugs> below.

[ List each incompatible change as a =head2 entry ]

=head1 Deprecations

XXX Any deprecated features, syntax, modules etc. should be listed here.

=head2 Making all warnings fatal is discouraged

The documentation for L<fatal warnings|warnings/Fatal Warnings> notes
that C<< use warnings FATAL => 'all' >> is discouraged
and provides stronger language about the risks of fatal warnings
in general.

=head2 Module removals

XXX Remove this section if inapplicable.

The following modules will be removed from the core distribution in a
future release, and will at that time need to be installed from CPAN.
Distributions on CPAN which require these modules will need to list them as
prerequisites.

The core versions of these modules will now issue C<"deprecated">-category
warnings to alert you to this fact.  To silence these deprecation warnings,
install the modules in question from CPAN.

Note that these are (with rare exceptions) fine modules that you are encouraged
to continue to use.  Their disinclusion from core primarily hinges on their
necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
not usually on concerns over their design.

=over

=item XXX

XXX Note that deprecated modules should be listed here even if they are listed
as an updated module in the L</Modules and Pragmata> section.

=back

[ List each other 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>.  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 *

XXX

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<attributes> has been upgraded from version 0.26 to 0.27.

=item *

L<Cwd> has been upgraded from version 3.55 to 3.56.

=item *

L<ExtUtils::Miniperl> has been upgraded from version 1.04 to 1.05.

=item *

L<IO::Socket::IP> has been upgraded from version 0.36 to 0.37.

=item *

L<Module::CoreList> has been upgraded from version 5.20150320 to 5.20150420.

Updated to cover the latest releases of Perl.

=item *

L<perl5db.pl> has been upgraded from 1.48 to 1.49.

The debugger would cause an assertion failure.  [perl #124127]

=item *

L<PerlIO::mmap> has been upgraded from version 0.013 to 0.014.

=item *

L<utf8> has been upgraded from version 1.15 to 1.16.

=item *

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

=item *

L<ExtUtils::ParseXS> has been upgraded from version 3.27 (with certain
components which were at version 3.25) to version 3.28.

=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.

=head2 New Diagnostics

XXX Newly added diagnostic messages go under here, separated into New Errors
and New Warnings

=head3 New Errors

=over 4

=item *

XXX L<message|perldiag/"message">

=back

=head3 New Warnings

=over 4

=item *

XXX L<message|perldiag/"message">

=back

=head2 Changes to Existing Diagnostics

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

=over 4

=item *

XXX Describe change here

=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 directory F<utils>.

[ List utility changes as a =head2 entry for each utility and =item
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]

=head2 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 summarizing, 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 Win32

F<miniperl.exe> is now built with C<-fno-strict-aliasing>, allowing
64-bit builds to complete on GCC 4.8. [perl #123976]

C<test-prep> again depends on C<test-prep-gcc> for GCC builds. [perl
#124221]

=back

=head1 Internal Changes

=over 4

=item *

5.21.2 introduced a new build option, C<-DPERL_OP_PARENT>, which causes
the last C<op_sibling> pointer to refer back to the parent rather than
being C<NULL>, and where instead a new flag indicates the end of the
chain. In this release, the new implementation has been revised; in
particular:

=over 4

=item *

On C<PERL_OP_PARENT> builds, the C<op_sibling> field has been renamed
C<op_sibparent> to reflect its new dual purpose. Since the intention is that
this field should primarily be accessed via macros, this change should be
transparent for code written to work under C<PERL_OP_PARENT>.

=item *

The newly-introduced C<op_lastsib> flag bit has been renamed C<op_moresib>
and its logic inverted; i.e. it is initialised to zero in a new op, and is
changed to 1 when an op gains a sibling.

=item *

The function C<Perl_op_parent> is now only available on C<PERL_OP_PARENT>
builds. Using it on a plain build will be a compile-timer error.

=item *

Three new macros, C<OpMORESIB_set>, C<OpLASTSIB_set>, C<OpMAYBESIB_set>
have been added, which are intended to be be a low-level portable way to
set C<op_sibling> / C<op_sibparent> while also updating C<op_moresib>.
The first sets the sibling pointer to a new sibling, the second makes the
op the last sibling, and the third conditionally does the first or second
action. The C<op_sibling_splice()> function is retained as a higher-level
interface that can also maintain consistency in the parent at the same time
(e.g. by updating C<op_first> and C<op_last> where appropriate).

=item *

The macro C<OpSIBLING_set>, added in 5.21.2, has been removed. It didn't
manipulate C<op_moresib> and has been superseded by C<OpMORESIB_set> et
al.

=item *

The C<op_sibling_splice> function now accepts a null C<parent> argument
where the splicing doesn't affect the first or last ops in the sibling
chain, and thus where the parent doesn't need to be updated accordingly.

=back


=back

=head1 Selected Bug Fixes

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

[ List each fix as a =item entry ]

=over 4

=item *

C<pack("D", $x)> and C<pack("F", $x)> now zero the padding on x86 long
double builds.  GCC 4.8 and later, under some build options, would
either overwrite the zero-initialized padding, or bypass the
initialized buffer entirely.  This caused F<op/pack.t> to fail.  [perl
#123971]

=item *

Extending an array cloned from a parent thread could result in
"Modification of a read-only value attempted" errors when attempting
to modify the new elements. [perl #124127]

=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.  Unfixed
platform specific bugs also go here.

[ List each fix as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Errata From Previous Releases

=over 4

=item *

XXX Add anything here that we forgot to add, or were mistaken about, in
the perldelta of a previous release.

=back

=head1 Obituary

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

=head1 Acknowledgements

XXX Generate this with:

  perl Porting/acknowledgements.pl v5.21.10..HEAD

=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