perlretut: Cleanup, nits

[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 v5.25.10

=head1 DESCRIPTION

This document describes differences between the 5.25.9 release and the 5.25.10
release.

If you are upgrading from an earlier release such as 5.25.8, first read
L<perl5259delta>, which describes differences between 5.25.8 and 5.25.9.

=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 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<XXX> has been upgraded from version A.xx to B.yy.

=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 *

Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30

This was changed to drop a leading C<v> in C<v5.30>, so it uses the same
style as other deprecation messages.

=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 Windows

=over 4

=item *

Support for compiling perl on Windows using Microsoft Visual Studio 2015
(containing Visual C++ 14.0) has been added.

This version of VC++ includes a completely rewritten C run-time library, some
of the changes in which mean that work done to resolve a socket close() bug in
perl #120091 and perl #118059 is not workable in its current state with this
version of VC++.  Therefore, we have effectively reverted that bug fix for
VS2015 onwards on the basis that being able to build with VS2015 onwards is
more important than keeping the bug fix.  We may revisit this in the future to
attempt to fix the bug again in a way that is compatible with VS2015.

These changes do not affect compilation with GCC or with Visual Studio versions
up to and including VS2013, i.e. the bug fix is retained (unchanged) for those
compilers.

Note that you may experience compatibility problems if you mix a perl built
with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
Some incompatibility may arise because of the bug fix that has been reverted
for VS2015 builds of perl, but there may well be incompatibility anyway because
of the rewritten CRT in VS2015 (e.g. see discussion at
http://stackoverflow.com/questions/30412951).

=back

=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 *

The C<op_class()> API function has been added. This is like the existing
C<OP_CLASS()> macro, but can more accurately determine what struct an op
has been allocated as. For example C<OP_CLASS()> might return
C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.

=item *

The output format of the C<op_dump()> function (as used by C<perl -Dx>)
has changed: it now displays an "ASCII-art" tree structure, and shows more
low-level details about each op, such as its address and class.

=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 *

Attempting to use the deprecated variable C<$#> as the object in an
indirect object method call could cause a heap use after free or
buffer overflow.  [perl #129274]

=item *

When checking for an indirect object method call in some rare cases
the parser could reallocate the line buffer but then continue to use
pointers to the old buffer.  [perl #129190]

=item *

Supplying a glob as the format argument to L<perlfunc/formline> would
cause an assertion failure.  [perl #130722]

=item *

Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
converted into a qr// operator, leaving extra elements on the stack to
confuse any surrounding expression.  [perl #130705]

=item *

Since 5.24.0 in some obscure cases, a regex which included code blocks
from multiple sources (e.g. via embedded via qr// objects) could end up
with the wrong current pad and crash or give weird results. [perl #129881]

=item *

Occasionally C<local()>s in a code block within a patterns weren't being
undone when the pattern matching backtracked over the code block.
[perl #126697]

=item *

Using C<substr()> to modify a magic variable could access freed memory
in some cases.  [perl #129340]

=item *

Perl 5.25.9 was fixed so that under C<use utf8>, the entire Perl program
is checked that the UTF-8 is wellformed.  It turns out that several edge
cases were missed, and are now fixed.  [perl #126310] was the original
ticket.

=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 v5.25.5..HEAD

=head1 Reporting Bugs

If you find what you think is a bug, you might check the perl bug database
at L<https://rt.perl.org/> .  There may also be information at
L<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 see
L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
for details of how to report the issue.

=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