Make key/push $scalar experimental

[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 v5.19.8

=head1 DESCRIPTION

This document describes differences between the 5.19.7 release and the 5.19.8
release.

If you are upgrading from an earlier release such as 5.19.6, first read
L<perl5197delta>, which describes differences between 5.19.6 and 5.19.7.

=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.

=head2 New C<\p{Unicode}> regular expression pattern property

This is a synonym for C<\p{Any}> and matches the set of Unicode-defined
code points 0 - 0x10FFFF.

=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

=head2 C<do> can no longer be used to call subroutines

The C<do SUBROUTINE(LIST)> form has resulted in a deprecation warning
since Perl v5.0.0, and is now a syntax error.

=head2 C<\p{}>, C<\P{}> matching has changed for non-Unicode code
points.

C<\p{}> and C<\P{}> are defined by Unicode only on Unicode-defined code
points (C<U+0000> through C<U+10FFFF>).  Their behavior on matching
these legal Unicode code points is unchanged, but there are changes for
code points C<0x110000> and above.  Previously, Perl treated the result
of matching C<\p{}> and C<\P{}> against these as C<undef>, which
translates into "false".  For C<\P{}>, this was then complemented into
"true".  A warning was supposed to be raised when this happened.
However, various optimizations could prevent the warning, and the
results were often counter-intuitive, with both a match and its seeming
complement being false.  Now all non-Unicode code points are treated as
typical unassigned Unicode code points.  This generally is more
Do-What-I-Mean.  A warning is raised only if the results are arguably
different from a strict Unicode approach, and from what Perl used to do.
Code that needs to be strictly Unicode compliant can make this warning
fatal, and then Perl always raises the warning.

Details are in L<perlunicode/Beyond Unicode code points>.

=head2 C<\p{All}> has been expanded to match all possible code points

The Perl-defined regular expression pattern element C<\p{All}>, unused
on CPAN, used to match just the Unicode code points; now it matches all
possible code points; that is, it is equivalent to C<qr/./s>.  Thus
C<\p{All}> is no longer synonymous with C<\p{Any}>, which continues to
match just the Unicode code points, as Unicode says it should.

=head1 Deprecations

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

=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

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<Encode> has been upgraded from version 2.56 to 2.57.

UTF-8 is no longer used in the C source (which some compilers didn't like), and
some POD errors have been fixed in the documentation.

=item *

The libnet module collection has been upgraded from version 1.23 to 1.24.

The handling of CRLF characters in L<Net::FTP> has been fixed.

=item *

L<IO::Socket::UNIX> has been upgraded from version 1.25 to 1.26.

Removed a warning about an ancient behaviour change and filled out the
SYNOPSIS. [perl #120981]

=item *

L<perl5db.pl> has been upgraded from version 1.42 to 1.43

Fix a crash in tab completion, where available. [perl #120827]

=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">

=item *

L<Matched non-Unicode code point 0x%X against Unicode property; may not be portable|perldiag/"Matched non-Unicode code point 0x%X against Unicode property; may not be portable">.
This replaces the message "Code point 0x%X is not Unicode, all \p{}
matches fail; all \P{} matches succeed".

=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 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 *

Distinct library basenames with C<d_libname_unique>.

When compiling perl with this option, the library files for XS modules are
named something "unique" -- for example, Hash/Util/Util.so becomes
Hash/Util/PL_Hash__Util.so.  This behavior is similar to what currently
happens on VMS, and serves as groundwork for the Android port.

=item *

C<sysroot> option to indicate the logical root directory under gcc and clang.

When building with this option set, both Configure and the compilers search
for all headers and libraries under this new sysroot, instead of /.

This is a huge time saver if cross-compiling, but can also help
on native builds if your toolchain's files have non-standard locations.

=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. ]

=over 4

=item *

Code related to supporting C<sfio> has been removed.

Perl 5.004 added support to use the native API of C<sfio>, AT&T's Safe/Fast
I/O library. This code still built with v5.8.0, albeit with many regression
tests failing, but was inadvertently broken before the v5.8.1 release,
meaning that it has not worked on any version of Perl released since then.
In over a decade we have received no bug reports about this, hence it is clear
that no-one is using this functionality on any version of Perl that is still
supported to any degree.

=back

=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 change as a =item entry ]

=over 4

=item newATTRSUB is now a macro

The public API newATTRSUB was previously a macro to the private
function Perl_newATTRSUB. Function Perl_newATTRSUB has been removed. newATTRSUB
is now macro to a different internal function.

=item Changes in warnings raised by C<utf8n_to_uvchr()>

This bottom level function decodes the first character of a UTF-8 string
into a code point.  It is accessible to C<XS> level code, but it's
discouraged from using it directly.  There are higher level functions
that call this that should be used instead, such as
L<perlapi/utf8_to_uvchr_buf>.  For completeness though, this documents
some changes to it.  Now, tests for malformations are done before any
tests for other potential issues.  One of those issues involves code
points so large that they have never appeared in any official standard
(the current standard has scaled back the highest acceptable code point
from earlier versions).  It is possible (though not done in CPAN) to
warn and/or forbid these code points, while accepting smaller code
points that are still above the legal Unicode maximum.  The warning
message for this now includes the code point if representable on the
machine.  Previously it always displayed raw bytes, which is what it
still does for non-representable code points.

=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 *

XXX

=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 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 v5.19.7..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