[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 v5.19.5

=head1 DESCRIPTION

This document describes differences between the 5.19.4 release and the 5.19.5
release.

If you are upgrading from an earlier release such as 5.19.3, first read
L<perl5194delta>, which describes differences between 5.19.3 and 5.19.4.

=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 ]

=head2 Unicode 6.3 now supported

Perl now supports and is shipped with Unicode 6.3 (though Perl may be
recompiled with any previous Unicode release as well).  A detailed list of
Unicode 6.3 changes is at L<http://www.unicode.org/versions/Unicode6.3.0/>.

=head2 Experimental Postfix Dereferencing

When the C<postderef> feature is in effect, the following syntactical
equivalencies are set up:

  $sref->$*;  # same as ${ $sref }  # interpolates
  $aref->@*;  # same as @{ $aref }  # interpolates
  $href->%*;  # same as %{ $href }
  $cref->&*;  # same as &{ $cref }
  $gref->**;  # same as *{ $gref }

  $gref->*{ $slot }; # same as *{ $gref }{ $slot }

  $aref->@[ ... ];  # same as @$aref[ ... ]  # interpolates
  $href->@{ ... };  # same as @$href{ ... }  # interpolates
  $aref->%[ ... ];  # same as %$aref[ ... ]
  $href->%{ ... };  # same as %$href{ ... }

Those marked as interpolating only interpolate if the associated
C<postderef_qq> feature is also enabled.  This feature is B<experimental> and
will trigger C<experimental::postderef>-category warnings when used, unless
they are suppressed.

For more information, consult L<the Postfix Dereference Syntax section of
perlref|perlref/Postfix Dereference Syntax>.

=head2 C<sub>s now take a C<prototype> attribute

When declaring or defining a C<sub>, the prototype can now be specified inside
of a C<prototype> attribute instead of in parens following the name.

For example, C<sub foo($$){}> could be rewritten as
C<sub foo : prototype($$){}>.

=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 ]

=head2 Functions C<PerlIO_vsprintf> and C<PerlIO_sprintf> have been removed

These two functions, undocumented, unused in CPAN, and problematic have been
removed.

=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 *

Perl has an optimizer for regular expression patterns.  It analyzes the pattern
to find things such as the minimum length a string has to be to match, etc.  It
now better handles code points that are above the Latin1 range.

=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<attributes> has been upgraded from version 0.21 to 0.22.

Support has been added for the C<prototype> attribute.

=item *

L<autodie> has been upgraded from version 2.21 to 2.22.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<CPAN::Meta> has been upgraded from version 2.132620 to 2.132830.

L<CPAN::Meta::Prereqs> now has a C<merged_requirements> method for combining
requirements across multiple phases and types, and an invalid 'meta-spec' is no
longer a fatal error.

=item *

L<CPAN::Meta::Requirements> has been upgraded from version 2.123 to 2.125.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<CPAN::Meta::YAML> has been upgraded from version 0.008 to 0.010.

No material changes have been made to the installed code other than the version
bump to keep in sync with the latest CPAN release.

=item *

L<Cwd> has been upgraded from version 3.44 to 3.45.

An obsolete #define has been removed from the XS code.

=item *

L<ExtUtils::Install> has been upgraded from version 1.60 to 1.61.

Some POD formatting errors in the documentation have been corrected.

=item *

L<ExtUtils::MakeMaker> has been upgraded from version 6.76 to 6.80.

Numerous updates and bug fixes are incorporated.  See the F<Changes> file for
full details.

=item *

L<feature> has been upgraded from version 1.33 to 1.34.

The new features C<postderef> and C<postderef_qq> have been added.

=item *

L<File::Fetch> has been upgraded from version 0.42 to 0.44.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<File::Glob> has been upgraded from version 1.21 to 1.22.

Since Perl 5.16, code that used C<glob> inside a thread had been
unintentionally sharing state between threads.  This has now been fixed.  [perl
#119897/#117823]

=item *

L<File::Temp> has been upgraded from version 0.2301 to 0.2304.

Required versions of other modules used are now listed more explicitly, L<base>
is now used instead of L<parent>, and L<Exporter> is no longer inherited from.

=item *

L<Getopt::Long> has been upgraded from version 2.41 to 2.42.

The floating point specifier C<name=f> no longer erroneously accepts values
like 1.2.3.  [cpan #88707]

=item *

L<HTTP::Tiny> has been upgraded from version 0.035 to 0.036.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<JSON::PP> has been upgraded from version 2.27202 to 2.27203.

A return/or precedence issue in C<_incr_parse> has been fixed.

=item *

L<List::Util> has been upgraded from version 1.32 to 1.35.

The list functions C<any>, C<all>, C<none>, C<notall> and C<product> have been
added, and C<reduce> and C<first> are now implemented even in the absence of
MULTICALL.

=item *

L<Module::CoreList> has been upgraded from version 2.99 to 3.00.

The list of Perl versions covered has been updated, %delta is now exported, and
a bug in C<is_core> whereby it wrongly assumed a linear list of releases has
been fixed.

=item *

L<Module::Metadata> has been upgraded from version 1.000018 to 1.000019.

Warnings are now disabled during version evaluation.

=item *

L<Parse::CPAN::Meta> has been upgraded from version 1.4407 to 1.4409.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<Perl::OSType> has been upgraded from version 1.005 to 1.006.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<PerlIO::scalar> has been upgraded from version 0.16 to 0.17.

An infinite loop when reading from a filehandle opened from a reference has
been fixed by first stringifying the reference.  [perl #119529]

=item *

The podlators modules have been upgraded from version 2.5.1 to 2.5.3.

Numerous updates and bug fixes are incorporated.  See the F<Changes> file in
the CPAN distribution for full details.

=item *

L<Test::Harness> has been upgraded from version 3.28 to 3.29.

All modules now use C<our> rather than C<use vars>, have C<use warnings>
enabled and C<use parent> instead of @ISA.

=item *

L<Test::Simple> has been upgraded from version 0.98 to 0.99.

Numerous updates and bug fixes are incorporated.  See the F<Changes> file for
full details.

=item *

L<threads> has been upgraded from version 1.87 to 1.89.

The documentation of C<alarm> and C<_handle> has been updated.

=item *

L<Unicode::Normalize> has been upgraded from version 1.16 to 1.17.

The module now C<die>s if it cannot get Unicode code points using C<unpack>.
(There is already a similar C<die> if Unicode code points cannot be stringified
using C<pack>.)

=item *

L<warnings> has been upgraded from version 1.19 to 1.20.

The new warnings category C<experimental::postderef> has been added.

=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<perlref>

=over 4

=item *

Documentation of the new postfix dereference syntax has been added.

=back

=head3 L<perlreguts>

=over 4

=item *

The documentation has been updated in the light of recent changes to
F<regcomp.c>.

=back

=head3 L<perlvar>

=over 4

=item *

Three L<English> variable names which have long been documented but do not
actually exist have been removed from the documentation.

=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 *

L<Attribute prototype(%s) discards earlier prototype attribute in same sub|perldiag/"Attribute prototype(%s) discards earlier prototype attribute in same sub">

(W misc) A sub was declared as sub foo : prototype(A) : prototype(B) {}, for
example.  Since each sub can only have one prototype, the earlier
declaration(s) are discarded while the last one is applied.

=item *

L<Postfix dereference is experimental|perldiag/"Postfix dereference is experimental">

(S experimental::postderef) This warning is emitted if you use the experimental
postfix dereference syntax.  Simply suppress the warning if you want to use the
feature, but know that in doing so you are taking the risk of using an
experimental feature which may change or be removed in a future Perl version:

    no warnings "experimental::postderef";
    use feature "postderef", "postderef_qq";
    $ref->$*;
    $aref->@*;
    $aref->@[@indices];
    ... etc ...

=item *

L<Prototype '%s' overridden by attribute 'prototype(%s)' in %s|perldiag/"Prototype '%s' overridden by attribute 'prototype(%s)' in %s">

(W prototype) A prototype was declared in both the parentheses after the sub
name and via the prototype attribute.  The prototype in parentheses is useless,
since it will be replaced by the prototype from the attribute before it's ever
used.

=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<a2p>

=over 4

=item *

A possible crash from an off-by-one error when trying to access before the
beginning of a buffer has been fixed.  [perl #120244]

=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 *

The new postfix dereference syntax is tested by a new test script,
F<t/op/postfixderef.t>.

=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 Windows

The Windows MinGW/gcc build was broken in Perl 5.19.4 for some recent versions
of gcc-4.8, including those from http://mingw-w64.sourceforge.net/ .  This has
now been fixed.  [perl #120236]

=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 *

XXX

=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<last> no longer returns values that the same statement has accumulated so
far, fixing amongst other things the long-standing bug that C<push @a, last>
would try to return the @a, copying it like a scalar in the process and
resulting in the error, "Bizarre copy of ARRAY in last."  [perl #3112]

=item *

An optimization in Perl 5.18 made incorrect assumptions causing a bad
interaction with the L<Devel::CallParser> CPAN module.  This was partially
fixed in Perl 5.19.4, but the fix was not sufficient and another fault has now
been corrected.

=item *

In some cases, closing file handles opened to pipe to or from a process, which
had been duplicated into a standard handle, would call perl's internal waitpid
wrapper with a pid of zero.  With the fix for [perl #85228] this zero pid was
passed to C<waitpid>, possibly blocking the process.  This wait for process
zero no longer occurs.  [perl #119893]

=item *

The code that parses regex backrefs (or ambiguous backref/octals) such as \123
did a simple atoi(), which could wrap round to negative values on long digit
strings and cause segmentation faults.  This has now been fixed.  [perl
#119505]

=item *

C<select> used to ignore magic on the fourth (timeout) argument, leading to
effects such as C<select> blocking indefinitely rather than the expected sleep
time.  This has now been fixed.  [perl #120102]

=item *

The class name in C<for my class $foo> is now parsed correctly.  In the case of
the second character of the class name being followed by a digit (e.g. 'a1b')
this used to give the error "Missing $ on loop variable".  [perl #120112]

=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 v5.19.4..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