=encoding utf8

=head1 NAME

perl5375delta - what is new for perl v5.37.5

=head1 DESCRIPTION

This document describes differences between the 5.37.4 release and the 5.37.5
release.

If you are upgrading from an earlier release such as 5.37.3, first read
L<perl5374delta>, which describes differences between 5.37.3 and 5.37.4.

=head1 Notice

Perl 5.28 introduced "thread-safe" locales on systems that supported
them, namely modern Windows, and systems supporting POSIX 2008 locale
operations.  These systems accomplish this by having per-thread locales,
while continuing to support the older global locale operations for code
that doesn't take the steps necessary to use the newer per-thread ones.

It turns out that some POSIX 2008 platforms have or have had buggy
implementations, which forced perl to not use them.  The
C<${^SAFE_LOCALES}> scalar variable contains 0 or 1 to indicate whether
or not the current platform is considered by perl to have a working
thread-safe implementation.  Some implementations have been fixed
already, but FreeBSD and Cygwin have been newly discovered to be
sufficiently buggy that the thread-safe operations are no longer used by
perl, starting in this release.  Hence, C<${^SAFE_LOCALES}> is now 0 for
them.  Older versions of perl can be configured to avoid these buggy
implementations by adding the F<Configure> option
C<-DNO_POSIX_2008_LOCALE>.

And 5.37.5 fixes a bug in all previous perls that led to locales not
being fully thread-safe.  The first thread that finishes caused
the main thread (named C<thread0>) to revert to the global locale in
effect at startup, discarding whatever the thread's locale had been
previously set to.  If any other thread had switched to the global
locale by calling C<switch_to_global_locale()> in XS code, those threads
would all share the global locale, and C<thread0> would not be
thread-safe.

=head1 Core Enhancements

=head2 Unicode 15.0 is supported

See L<https://www.unicode.org/versions/Unicode15.0.0/> for details.

=head1 Performance Enhancements

=over 4

=item *

Creating an anonymous sub no longer generates an C<srefgen> op, the
reference generation is now done in the C<anoncode> or C<anonconst>
op, saving runtime.  [github #20290]

=back

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<B::Deparse> has been upgraded from version 1.69 to 1.70.

=item *

L<JSON::PP> has been upgraded from version 4.11 to 4.12.

=item *

L<Math::Complex> has been upgraded from version 1.5902 to 1.5903.

=item *

L<Memoize> has been upgraded from version 1.10 to 1.14.

=item *

L<Module::CoreList> has been upgraded from version 5.20220920 to 5.20221020.

=item *

L<Net::Ping> has been upgraded from version 2.74 to 2.75.

=item *

L<perl5db.pl> has been upgraded from version 1.76 to 1.77.

Supplying end of file to the debugger now acts like C<q>, as
documented. [github #20307]

=item *

L<POSIX> has been upgraded from version 2.06 to 2.07.

=item *

L<threads> has been upgraded from version 2.29 to 2.31.

=item *

L<warnings> has been upgraded from version 1.58 to 1.59.

=back

=head1 Documentation

=head2 New Documentation

=head3 L<perlhacktips/Writing safer macros>

=over 4

=item *

A new section has been added to discuss pitfalls and solutions to using
C macros in C and XS code.

=back

=head3 L<perlhacktips/Choosing good symbol names>

=over 4

=item *

A new section has been added to discuss unexpected gotchas with names.
(Actually this section was added in v5.37.4, but notice of it was
inadvertently left out of that perl delta.)

=back

=head1 Configuration and Compilation

=over 4

=item *

Remove ancient and broken GCC for VMS support

=item *

Remove vestigial reference to /VAXC qualifier

=item *

Remove sharedperl option on VMS

=item *

VMS now has mkostemp

=back

=head1 Testing

=over 4

=item *

t/test.pl: Add ability to cancel an watchdog timer

=back

=head1 Acknowledgements

Perl 5.37.5 represents approximately 4 weeks of development since Perl
5.37.4 and contains approximately 40,000 lines of changes across 220 files
from 24 authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 31,000 lines of changes to 97 .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 5.37.5:

Alex, Bram, Craig A. Berry, Dan Book, Elvin Aslanov, Felipe Gasper, Graham
Knop, James E Keenan, Karen Etheridge, Karl Williamson, Kenichi Ishigaki,
Leon Timmermans, Nathan Mills, Nicolas R, Paul Evans, Peter John Acklam,
Philippe Bruhat (BooK), Ricardo Signes, Richard Leach, TAKAI Kousuke, Todd
Rinaldo, Tony Cook, Unicode Consortium, Yves Orton.

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://github.com/Perl/perl5/issues>.  There may also be information at
L<http://www.perl.org/>, the Perl Home Page.

If you believe you have an unreported bug, please open an issue at
L<https://github.com/Perl/perl5/issues>.  Be sure to trim your bug down to a
tiny but sufficient test case.

If the bug you are reporting has security implications which make it
inappropriate to send to a public issue tracker, 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
