perldelta for e45d8982ae

[perl5.git] / pod / perl5195delta.pod

=encoding utf8

=head1 NAME

perl5195delta - 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 Core Enhancements

=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 Incompatible Changes

=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 Performance Enhancements

=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

=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 in
the CPAN distribution 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<IPC::Cmd> has been upgraded from version 0.84 to 0.84_01.

No changes have been made to the installed code, but a test script has been
fixed for Solaris (and potentially other SVR* variants).

=item *

L<JSON::PP> has been upgraded from version 2.27202_01 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_06 to 0.99.

Numerous updates and bug fixes are incorporated.  See the F<Changes> file in
the CPAN distribution 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<Unicode::UCD> has been upgraded from version 0.54 to 0.55.

An internals-only change has been made to handle changes in format within some
character database tables.

=item *

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

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

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=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>.

=head2 New Diagnostics

=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

=head1 Utility Changes

=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 Testing

=over 4

=item *

The new prototype attribute syntax is tested by a new test script,
F<t/op/attrproto.t>.

=item *

The new test script F<t/io/closepid.t> tests that C<close> on the original of a
popen handle dupped to a standard handle no longer blocks internally on
C<waitpid(0, ...)>.

=item *

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

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=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 Selected Bug Fixes

=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 Acknowledgements

Perl 5.19.5 represents approximately 4 weeks of development since Perl 5.19.4
and contains approximately 76,000 lines of changes across 710 files from 27
authors.

Perl continues to flourish into its third decade thanks to a vibrant community
of users and developers. The following people are known to have contributed the
improvements that became Perl 5.19.5:

Andy Dougherty, Brian Fraser, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn
Ilmari Mannsåker, Daniel Dragan, David Golden, David Mitchell, David Nicol,
Dominic Hargreaves, Eric Brine, Father Chrysostomos, Gideon Israel Dsouza, Hio,
James E Keenan, Jerry D. Hedden, Jesse Luehrs, Karl Williamson, Matthew
Horsfall, Max Maischein, Neil Bowers, Nicholas Clark, Peter Martini, Philip
Guenther, Ricardo Signes, Steve Hay, Tony Cook.

The list above is almost certainly incomplete as it is automatically generated
from version control history. In particular, it does not include the names of
the (very much appreciated) contributors who reported issues to the Perl bug
tracker.

Many of the changes included in this version originated in the CPAN modules
included in Perl's core. We're grateful to the entire CPAN community for
helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see
the F<AUTHORS> file in the Perl source distribution.

=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