=encoding utf8

=head1 NAME

perl5376delta - what is new for perl v5.37.6

=head1 DESCRIPTION

This document describes differences between the 5.37.5 release and the 5.37.6
release.

If you are upgrading from an earlier release such as 5.37.4, first read
L<perl5375delta>, which describes differences between 5.37.4 and 5.37.5.

=head1 Incompatible Changes

=head2 L<C<utf8::upgrade()>|utf8/Utility functions>

Starting in this release, if the input string is C<undef>, it remains
C<undef>.  Previously it would be changed into a defined, zero-length
string.

=head1 Modules and Pragmata

=head2 New Modules and Pragmata

=over 4

=item *

Support for RFC-18, C<use feature "module_true";> has been added to
the default feature bundle for 5.37 and later. It may also be used
explicitly. When enabled inside of a module the module does not need
to return true explicitly, and in fact the return will be forced to
a simple true value regardless of what it originally was.

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Storable> has been upgraded from version 3.27 to 3.28.

The C<STORABLE_freeze> callback now supports regular expression
objects.

The error message when Storable attempts to call C<STORABLE_freeze>
for an unsupported type such as GLOBs has been improved from
C<"Unexpected object type (8) in store_hook()"> to indicate the perl
object type and the class.

=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, open an issue
at L<https://github.com/Perl/perl5/issues>.

=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 Errors

None

=head3 New Warnings

None

=head2 Changes to Existing Diagnostics

=over 4

=item *

Various warnings that used to produce parenthesized hints underneath the
main warning message and after its "location data" were chanaged to put
the hint inline with the main message. For instance:

 Bareword found where operator expected at -e line 1, near "foo bar"
     (Do you need to predeclare foo?)

will now look like this but as one line:

 Bareword found where operator expected (Do you need to predeclare
 foo?) at -e line 1, near "foo bar"

as a result such warnings will no longer trigger C<$SIG{__WARN__}>
twice, and the hint will be visible when fatal warnings is in effect.

=back

=head1 Utility Changes

=head2 Configure

None

=head1 Configuration and Compilation

=over 4

=item *

C<I32>/C<U32> formatting symbols added in 5.37.2, C<I32df>, C<U32xf>, etc.
used to be defined in F<perl.h> using preprocessor conditionals.
They are now determined in F<Configure> and defined in F<config.h>.

=back

=head1 Testing

=over 4

=item *

Tests were added and changed to reflect the other additions and changes
in this release.

=back

=head1 Platform Support

=over 4

=item Windows

stat() now works on AF_UNIX socket files. [github #20204]

readlink() now returns the C<PrintName> from a symbolic link reparse
point instead of the C<SubstituteName>, which should make it better
match the name the link was created with.  [github #20271]

=back

=head1 Internal Changes

=over 4

=item *

A new magic type C<PERL_MAGIC_extvalue> has been added. This is available for
use like C<PERL_MAGIC_ext>, but is a value magic: upon localization the new
value will not be magical.

=item *

The C<SSNEW()>, C<SSNEWt()>, C<SSNEWa()> and C<SSNEWat()> APIs now
return a C<SSize_t> value.  The C<SSPTR()> and C<SSPTRt()> macros now
expect a C<SSize_t> parameter, and enforce that on debugging builds.
[github #20411]

=item *

Filenames in cops are now refcounted under threads.
Under threads we were copying the filenames into each opcode. This is because in
theory opcodes created in one thread can be destroyed in another.
The change adds a new struct/type RCPV, which is a refcounted
string using shared memory. This is implemented in such a way that code
that previously used a char * can continue to do so, as the refcounting
data is located a specific offset before the char * pointer itself.

[commit 6760f691a95ab3a37fd59212795de2b1a7cf7888]

=back

-=head1 Selected Bug Fixes

=over 4

=item *

Fixes to memory handling for C<PL_splitstr>:

=over

=item *

If a thread was created the allocated string would be freed twice.

=item *

If two C<-F> switches were supplied the memory allocated for the first
switch wouldn't be freed.

=back

=back

=head1 Known Problems

None

=head1 Errata From Previous Releases

None

=head1 Acknowledgements

Perl 5.37.6 represents approximately 4 weeks of development since Perl
5.37.5 and contains approximately 16,000 lines of changes across 230 files
from 26 authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 12,000 lines of changes to 130 .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 5.37.6:

Alexander Nikolov, Andreas König, Aristotle Pagaltzis, Bram, Branislav
Zahradník, chromatic, David Mitchell, E. Choroba, Elvin Aslanov, Felipe
Gasper, Graham Knop, James E Keenan, Joe McMahon, Johan Vromans, Karl
Williamson, Leon Timmermans, Mattia Barbon, Max Maischein, Paul Evans,
Ricardo Signes, Richard Leach, TAKAI Kousuke, Todd Rinaldo, Tom Stellard,
Tony Cook, 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
