perldelta update

[perl5.git] / pod / perldelta.pod

=encoding utf8

=for comment
This has been completed up to 8367b6810 except for:
747627ec455e0765e07733ece1545aa3f728a00a (Steffen Müller)
dd35fa16610ef2fa0d46f5129e626b99cf350d77 (H. Merijn Brand)
e64345f82d66a32f6da47acf482e7e6c9282b433 (Steffen Müller)
f1d35e3443aa8451bf47be80983076fe28626113 (Karthik Rajagopalan)

=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 v5.15.2

=head1 DESCRIPTION

This document describes differences between the 5.15.1 release and
the 5.15.2 release.

If you are upgrading from an earlier release such as 5.15.0, first read
L<perl5151delta>, which describes differences between 5.15.0 and
5.15.1.

=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.

[ List each enhancement as a =head2 entry ]

=head2 Subroutines in the CORE namespace

Many Perl keywords are now available as subroutines in the CORE namespace.
These cannot be called through references or via C<&foo> syntax yet, but
must be called as barewords.  In other words, you can now do this:

    BEGIN { *entangle = \&CORE::tie }
    entangle $variable, $package, @args;

This currently works for overridable keywords other than C<dump> and the
infix operators.

Work is under way to allow these subroutines to be called through
references.

=head2 C<__FILE__()> Syntax

The C<__FILE__>, C<__LINE__> and C<__PACKAGE__> tokens can now be written
with an empty pair of parentheses after them.  This makes them parse the
same way as C<time>, C<fork> and other built-in functions.

=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 ]

=head2 C<UNIVERSAL::VERSION> now returns $VERSION

C<UNIVERSAL::VERSION> now return whatever is in $VERSION, instead of
returning $VERSION converted to a version object and then to a string.
As a result, it no longer parses the version when called without arguments,
so it no longer dies in that case for malformed versions.  This allows
custom version number parsers to use C<< ->VERSION >> to retrieve the
version number, as was the case in Perl 5.8 [perl #95544].

=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 *

XXX

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<B> has been upgraded from version 1.30 to version 1.31

The XS code has changed slightly, as it was too tightly coupled to
the contents of the header F<embedvar.h>. Documentation in L<B::Terse>
and L<B::Xref> has been improved, hence their versions have been increased.

=item *

L<CPAN> has been upgraded from version 1.9600 to version 1.9800

=item *

L<CPANPLUS> has been upgraded from version 0.9108 to version 0.9109

Fixed support for v-strings and x.y.z versions with v5.8.4

=item *

L<CPAN::Meta> has been upgraded from version 2.110930_001 to version 2.112150

Stringify any objects encountered during conversion.

Clarified that file paths in the 'provides' section must be in
Unix-style (i.e. forward slashes)

=item *

L<DB_File> has been upgraded from version 1.822 to version 1.824

Will now croak if attempt to freeze/thaw DB_File object [RT #69985]

=item *

L<diagnostics> has been upgraded from version 1.23 to 1.24.

It now supports the %u formatting code.  Previously it was unable to find
descriptions for messages whose entries in L<perldiag> included that code
[perl #94988].

=item *

L<Encode> has been upgraded from version 2.43 to version 2.44

Addressed 'decode_xs n-byte heap-overflow' security bug in Unicode.xs

=item *

L<ExtUtils::Install> has been upgraded from version 1.56 to version 1.57.

There is no change to ExtUtils::Install other than the version number
increase, but L<ExtUtils::Installed> has been upgraded from version 1.999_001
to version 1.999002 and a new C<skip_cwd> attribute has been added.

=item *

L<ExtUtils::MakeMaker> has been upgraded from version 6.58 to version 6.59

=item *

L<IPC::Open3> has been upgraded from version 1.11 to 1.12.

C<open3> with "-" for the program name works once more.  This was broken in
version 1.06 (and hence in Perl 5.14.0) [perl #95748].

=item *

L<Module::Build> has been upgraded from version 0.3800 to version 0.39_01.

Pod to HTML internals changed to support revisions to Pod::Html in core.
Also fixes some minor bugs. [rt.cpan.org #68585] [rt.cpan.org #67893]
[rt.cpan.org #67008]

=item *

L<Module::Load> has been upgraded from version 0.18 to version 0.20

=item *

L<Module::Metadata> has been upgraded from version 1.000004 to version 1.000005

Added C<new_from_handle()> method.

=item *

L<Params::Check> has been upgraded from version 0.28 to version 0.32

=item *

L<PerlIO::via> has been upgraded from version 0.11 to version 0.12.

The only change is a correction in the documentation.

=item *

L<Term::ANSIColor> has been upgraded from version 3.00 to version 3.01

Only interpret an initial array reference as a list of colors, not any initial
reference, allowing the colored function to work properly on objects with
stringification defined.

=item *

L<Unicode::Collate> has been upgraded from version 0.77 to version 0.78

=item *

L<Unicode::Normalize> has been upgraded from version 1.12 to version 1.13

=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<perlexperiment>

This document is intended to provide a list of experimental features in
Perl.  It is still a work in progress.

=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<perlsub>

=over 4

=item *

The ($;) prototype syntax, which has existed for rather a long time, is now
documented in L<perlsub>.  It allows a unary function to have the same
precedence as a list operator.

=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 that links to perldiag,
  e.g.

  =item *

  L<Invalid version object|perldiag/"Invalid version object">
]

=head2 New Diagnostics

XXX Newly added diagnostic messages go here

=head3 New Errors

=over 4

=item *

L<&CORE::%s cannot be called directly|perldiag/"&CORE::%s cannot be called directly">

(F) You tried to call a subroutine in the C<CORE::> namespace
with C<&foo> syntax or through a reference.  The subroutines
in this package cannot yet be called that way, but must be
called as barewords.  Something like this will work:

    BEGIN { *shove = \&CORE::push; }
    shove @array, 1,2,3; # pushes on to @array

=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 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<perlivp>

=over 4

=item *

Fixed a bug whereby other perls under the current directory could cause
false positive failures.

=item *

Tests for .ph files have been removed, as these test have been optional since
2005 and .ph files are no longer generated during installation.

=back

=head3 L<splain>

See the entry for C<< diagnostics >> in L</Updated Modules and Pragmata>,
above.

=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 *

F<makedef.pl> has been refactored. This should have no noticeable affect on
any of the platforms that use it as part of their build (AIX, VMS, Win32).

=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. ]

=over 4

=item HP-UX PA-RISC/64 now supports gcc-4.x

A fix to correct the socketsize now makes the test suite pass on HP-UX
PA-RISC for 64bitall builds.

=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 *

F<embedvar.h> has been simplified, and one level of macro indirection for
PL_* variables has been removed for the default (non-multiplicity)
configuration. PERLVAR*() macros now directly expand their arguments to
tokens such as C<PL_defgv>, instead of expanding to C<PL_Idefgv>, with
F<embedvar.h> defining a macro to map C<PL_Idefgv> to C<PL_defgv>. XS code
which has unwarranted chumminess with the implementation may need updating.

=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 *

Locking a subroutine (via C<lock &sub>) is no longer a compile-time error
for regular subs.  For lvalue subroutines, it no longer tries to return the
sub as a scalar, resulting in strange side effects like C<ref \$_>
returning "CODE" in some instances.

C<lock &sub> is now a run-time error if L<threads::shared> is loaded (a
no-op otherwise), but that may be rectified in a future version.

=item *

The prototypes of several built-in functions--C<getprotobynumber>, C<lock>,
C<not> and C<select>--have been corrected, or at least are now closer to
reality than before.

=item *

Most dereferencing operators (C<${}>, etc.) used to call C<FETCH> twice on
a tied operand when doing a symbolic dereference (looking up a variable by
name, which is not permitted under C<use strict 'refs'>).  Only C<&{}> did
not have this problem.  This has been fixed.

=item *

A minor regression introduced in 5.15.0 has been fixed.  Dereferencing a
magical mortal (e.g., the return value of C<delete> on a tied hash element)
explicitly returned from a subroutine called recursively was not calling
C<FETCH>.  This would affect code like C<@{ foo() }> where the C<foo> sub
contains C<return delete $hash{elem}> and is calling itself.

=item *

A panic involving the combination of the regular expression modifiers
C</aa> and the C<\b> escape sequence introduced in 5.14.0 has been
fixed [perl #95964].

=item *

stat() would always return the inode number as an IV, even when the
original was unsigned, or too large to fit in an IV.  stat() now
returns the inode number as the type that would best preserve the
original value. [perl #84590]

=item *

The combination of the regular expression modifiers C</aa> and the C<\b>
and C<\B> escape sequences did not work properly on UTF-8 encoded
strings.  All non-ASCII characters under C</aa> should be treated as
non-word characters, but what was happening was that Unicode rules were
used to determine wordness/non-wordness for non-ASCII characters.  This
is now fixed [perl #95968].

=item *

Infinite loops like C<1 while 1> used to stop C<strict 'subs'> mode from
working for the rest of the block.t

=item *

The C<\h>, C<\H>, C<\v> and C<\V> regular expression metacharacters used to
cause a panic error message when attempting to match at the end of the
string [perl #96354].

=item *

For list assignments like C<($a,$b) = ($b,$a)>, Perl has to make a copy of
the items on the right-hand side before assignment them to the left.  For
efficiency's sake, it assigns the values on the right straight to the items
on the left no variable is mentioned on both sides, as in
C<($a,$b) = ($c,$d)>.  The logic for determining when it can cheat was
faulty, in that C<&&> and C<||> on the right-hand side could fool it.  So
C<($a,$b) = $some_true_value && ($b,$a)> would end up assigning the value
of C<$b> to both scalars.

=item *

Perl no longer tries to apply lvalue context to the string in
C<("string", $variable) ||= 1> (which used to be an error).  Since the
left-hand side of C<||=> is evaluated in scalar context, that's a scalar
comma operator, which gives all but the last item void context.  There is
no such thing as void lvalue context, so it was a mistake for Perl to try
to force it [perl #96942].

=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 Generate this with:

  perl Porting/acknowledgements.pl v5.15.1..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 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