path: root/pod/perl5296delta.pod

=encoding utf8

=head1 NAME

perl5296delta - what is new for perl v5.29.6

=head1 DESCRIPTION

This document describes differences between the 5.29.5 release and the 5.29.6
release.

If you are upgrading from an earlier release such as 5.29.4, first read
L<perl5295delta>, which describes differences between 5.29.4 and 5.29.5.

=head1 Security

=head2 [CVE-2018-18312] Heap-buffer-overflow write in S_regatom (regcomp.c)

A crafted regular expression could cause heap-buffer-overflow write during
compilation, potentially allowing arbitrary code execution. (This was 
actually fixed in 5.29.4, but not announced as a security fix at the time).
L<[perl #133423]|https://rt.perl.org/Ticket/Display.html?id=133423>

=head1 Performance Enhancements

=over 4

=item *

Optimization of C<IV> to C<UV> conversions.
L<[perl #133677]|https://rt.perl.org/Ticket/Display.html?id=133677>.

=item *

Speed up of the integer stringification algorithm by processing
two digits at a time instead of one.
L<[perl #133691]|https://rt.perl.org/Ticket/Display.html?id=133691>.

=item *

Improvements based on LGTM analysis and recommendation.
(L<https://lgtm.com/projects/g/Perl/perl5/alerts/?mode=tree>). 
L<[perl #133686]|https://rt.perl.org/Ticket/Display.html?id=133686>.
L<[perl #133699]|https://rt.perl.org/Ticket/Display.html?id=133699>.

=item *

Code optimizations in F<regcomp.c>, F<regcomp.h>, F<regexec.c>.

=back

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Config::Perl::V>. has been upgraded from version 0.30 to 0.32. This was due
to a new configuration variable that has influence on binary compatibility:
C<USE_THREAD_SAFE_LOCALE>.

=item *

L<ExtUtils::ParseXS> has been upgraded from version 3.39 to 3.40.
C<OUTLIST> parameters are no longer incorrectly included in the
automatically generated function prototype.
L<[perl #133654]|https://rt.perl.org/Ticket/Display.html?id=133654>.

=item *

L<File::Find> has been upgraded from version 1.34 to 1.35.
C<$File::Find::dont_use_nlink> now defaults to 1 on all
platforms.
L<[perl #133673]|https://rt.perl.org/Ticket/Display.html?id=133673>.

=item *

L<Module::CoreList> has been upgraded from version 5.20181120 to 5.20181218.

=item *

L<POSIX> has been upgraded from version 1.85 to 1.86.

=item *

L<Storable> has been upgraded from version 3.13 to 3.14.

Storable no longer probes for recursion limits at build time.
L<[perl #133708]|https://rt.perl.org/Ticket/Display.html?id=133708>
and others.

Metasploit exploit code was included to test for CVE-2015-1992
detection, this caused anti-virus detections on at least one AV suite.
The exploit code has been removed and replaced with a simple
functional test.
L<[perl #133706]|https://rt.perl.org/Ticket/Display.html?id=133706>

=item *

L<Test::Simple> has been upgraded from version 1.302140 to 1.302141.

=item *

L<threads::shared> has been upgraded from version 1.58 to 1.59.

=back

=head1 Documentation

=head2 Changes to Existing Documentation

We have attempted to update the documentation to reflect the changes
listed in this document.  If you find any we have missed, send email
to L<perlbug@perl.org|mailto:perlbug@perl.org>.

Additionally, the following selected changes have been made:

=head3 L<perlfunc>

=over 4

=item *

Clarification of behaviour of C<reset EXPR>.

=back

=head3 L<perlreref>

=over 4

=item *

Clarification of the syntax of /(?(cond)yes)/.

=back

=head3 L<perlop>

=over

=item *

We no longer have null (empty line) here doc terminators, so 
L<perlop> should not refer to them.

=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 Changes to Existing Diagnostics

=over 4

=item *

Under C<< -Dr >> (or C<< use re 'Debug' >>) the compiled regex engine
program is displayed. It used two different spellings for I<< infinity >>,
C<< INFINITY >>, and C<< INFTY >>. It now uses the latter exclusively,
as that spelling has been around the longest.

=back

=head1 Utility Changes

=head2 L<xsubpp>

=over 4

=item *

The generated prototype (with C<< PROTOTYPES: ENABLE >>) would include
C<< OUTLIST >> parameters, but these aren't arguments to the perl function.
This has been rectified.
L<[perl #133654]|https://rt.perl.org/Ticket/Display.html?id=133654>.

=back

=head1 Testing

Tests were added and changed to reflect the other additions and
changes in this release.  Furthermore, these significant changes were
made:

=over 4

=item *

Some tests in F<< t/io/eintr.t >> caused the process to hang on
pre-16 Darwin. These tests are skipped for those version of Darwin.

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item Cygwin

Cygwin doesn't make C<< cuserid >> visible.

=item Win32 Mingw

C99 math functions are now available.

=back

=head1 Internal Changes

=over 4

=item *

Two new regnodes have been introduced C<< EXACT_ONLY8 >>, and
C<< EXACTFU_ONLY8 >>. They're equivalent to C<< EXACT >> and C<< EXACTFU >>,
except that they contain a code point which requires UTF-8 to
represent/match. Hence, if the target string isn't UTF-8, we know
it can't possibly match, without needing to try.

=item *

C<< print_bytes_for_locale() >> is now defined if C<< DEBUGGING >>,
Prior, it didn't get defined unless C<< LC_COLLATE >> was defined
on the platform.

=back

=head1 Selected Bug Fixes

=over 4

=item *

If an in-place edit is still in progress during global destruction and
the process exit code (as stored in C<$?>) is zero, perl will now
treat the in-place edit as successful, replacing the input file with
any output produced.

This allows code like:

  perl -i -ne 'print "Foo"; last'

to replace the input file, while code like:

  perl -i -ne 'print "Foo"; die'

will not.  Partly resolves
L<[perl #133659]|https://rt.perl.org/Ticket/Display.html?id=133659>.

=item *

A regression in 5.28 caused the following code to fail

 close(STDIN); open(CHILD, "|wc -l")'

because the child's stdin would be closed on exec. This has now been fixed.

=item *

Fixed an issue where compiling a regexp containing both compile-time
and run-time code blocks could lead to trying to compile something
which is invalid syntax.

=item *

Fixed build failures with C<< -DNO_LOCALE_NUMERIC >> and
C<< -DNO_LOCALE_COLLATE >>.
L<[perl #133696]|https://rt.perl.org/Ticket/Display.html?id=133696>.

=item *

Prevent the tests in F<< ext/B/t/strict.t >> from being skipped.
L<[perl #133713]|https://rt.perl.org/Ticket/Display.html?id=133713>.

=item *

C<< /di >> nodes ending or beginning in I<s> are now C<< EXACTF >>. We do not
want two C<< EXACTFU >> to be joined together during optimization,
and to form a C<< ss >>, C<< sS >>, C<< Ss >> or C<< SS >> sequence;
they are the only multi-character sequences which may match differently
under C<< /ui >> and C<< /di >>. 

=back

=head1 Errata From Previous Releases

=over 4

=item *

The upper limit C<"n"> specifiable in a regular expression
quantifier of the form C<"{m,n}"> has been doubled to 65534.

The meaning of an unbounded upper quantifier C<"{m,}"> remains unchanged.
It matches 2**31 - 1 times on most platforms, and more on ones where a C
language short variable is more than 4 bytes long.

The text above is what perl5294delta should have said.  Instead it said
"The maximum number of times a pattern can match has been doubled to 65535"
That statement was wrong.  Try to forget you ever saw it.

=back

=head1 Acknowledgements

Perl 5.29.6 represents approximately 4 weeks of development since Perl
5.29.5 and contains approximately 5,000 lines of changes across 230 files
from 19 authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 2,600 lines of changes to 150 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant
community of users and developers. The following people are known to have
contributed the improvements that became Perl 5.29.6:

Aaron Crane, Abigail, Dagfinn Ilmari Mannsåker, David Mitchell, Dominic
Hargreaves, E. Choroba, Eugen Konkov, H.Merijn Brand, James E Keenan, Jerry
D. Hedden, Karen Etheridge, Karl Williamson, Leon Timmermans, Niko Tyni,
Petr Písař, Sisyphus, Steve Hay, Tomasz Konojacki, 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 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 Give Thanks

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5,
you can do so by running the C<perlthanks> program:

    perlthanks

This will send an email to the Perl 5 Porters list with your show of thanks.

=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