=encoding utf8

=head1 NAME

perl5312delta - what is new for perl v5.31.2

=head1 DESCRIPTION

This document describes differences between the 5.31.1 release and the 5.31.2
release.

If you are upgrading from an earlier release such as 5.31.0, first read
L<perl5311delta>, which describes differences between 5.31.0 and 5.31.1.

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Devel::PPPort> has been upgraded from version 3.53 to 3.54.

=item *

L<Exporter> has been upgraded from version 5.73 to 5.74.

=item *

L<IPC::Cmd> has been upgraded from version 1.02 to 1.04.

=item *

L<JSON::PP> has been upgraded from version 4.02 to 4.04.

=item *

L<Module::CoreList> has been upgraded from version 5.20190620 to 5.20190720.

=item *

L<Opcode> has been upgraded from version 1.43 to 1.44.

=item *

L<PerlIO::encoding> has been upgraded from version 0.27 to 0.28.

=item *

L<Pod::Simple> has been upgraded from version 3.38 to 3.39.

=item *

L<threads::shared> has been upgraded from version 1.60 to 1.61.

=back

=head1 Diagnostics

=head2 New Diagnostics

=head3 New Errors

=over 4

=item *

C<L<No digits found for %s literal|perldiag/"No digits found for %s literal">>

(F) No hexadecimal digits were found following C<0x> or no binary digits were
found following C<0b>.

=back

=head2 Changes to Existing Diagnostics

=over 4

=item *

C<\N{} here is restricted to one character> is now emitted in the same
circumstances where previously C<\N{} in inverted character class or as a range
end-point is restricted to one character> was.

This is due to new circumstances having been added in Perl 5.30 that weren't
covered by the earlier wording.

=back

=head1 Configuration and Compilation

=over 4

=item *

The C<ECHO> macro is now defined.  This is used in a C<dtrace> rule that was
originally changed for FreeBSD, and the FreeBSD make apparently predefines it.
The Solaris make does not predefine C<ECHO> which broke this rule on Solaris.
L<[perl #134218]|https://rt.perl.org/Ticket/Display.html?id=134218>

=item *

Bison versions 3.1 through 3.4 are now supported.

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item Linux

C<cc> will be used to populate C<plibpth> if C<cc> is C<clang>.
L<[perl #134189]|https://rt.perl.org/Ticket/Display.html?id=134189>

=item VMS

C<-Duse64bitint> is now the default on VMS.

=back

=head1 Internal Changes

=over 4

=item *

The PERL_DESTRUCT_LEVEL environment variable was formerly only honoured on perl
binaries built with DEBUGGING support.  It is now checked on all perl builds.
Its normal use is to force perl to individually free every block of memory
which it has allocated before exiting, which is useful when using automated
leak detection tools such as valgrind.

=item *

The API eval_sv() now accepts a C<G_RETHROW> flag.  If this flag is set and an
exception is thrown while compiling or executing the supplied code, it will be
rethrown, and eval_sv() will not return.
L<[perl #134177]|https://rt.perl.org/Ticket/Display.html?id=134177>

=item *

As part of the fix for
L<[perl #2754]|https://rt.perl.org/Ticket/Display.html?id=2754> perl_parse()
now returns non-zero if exit(0) is called in a C<BEGIN>, C<UNITCHECK> or
C<CHECK> block.

=item *

Most functions which recursively walked an op tree during compilation have been
made non-recursive.  This avoids SEGVs from stack overflow when the op tree is
deeply nested, such as C<$n == 1 ? "one" : $n == 2 ? "two" : ....> (especially
in code which is auto-generated).

This is particularly noticeable where the code is compiled within a separate
thread, as threads tend to have small stacks by default.

=back

=head1 Selected Bug Fixes

=over 4

=item *

Parsing incomplete hex or binary literals was changed in 5.31.1 to treat such a
literal as just the 0, leaving the following C<x> or C<b> to be parsed as part
of the next token.  This could lead to some silent changes in behaviour, so now
incomplete hex or binary literals produce a fatal error.
L<[perl #134125]|https://rt.perl.org/Ticket/Display.html?id=134125>

=item *

eval_pv()'s I<croak_on_error> flag will now throw even if the exception is a
false overloaded value.
L<[perl #134177]|https://rt.perl.org/Ticket/Display.html?id=134177>

=item *

C<INIT> blocks and the program itself are no longer run if exit(0) is called
within a C<BEGIN>, C<UNITCHECK> or C<CHECK> block.
L<[perl #2754]|https://rt.perl.org/Ticket/Display.html?id=2754>

=item *

C<<< open my $fh, ">>+", undef >>> now opens the temporary file in append mode
- writes will seek to the end of file before writing.
L<[perl #134221]|https://rt.perl.org/Ticket/Display.html?id=134221>

=item *

Fixed a SEGV when searching for the source of an uninitialized value warning on
an op whose subtree includes an OP_MULTIDEREF.
L<[perl #134275]|https://rt.perl.org/Ticket/Display.html?id=134275>

=back

=head1 Known Problems

=over 4

=item *

The VC++ 6.0 build on Windows is currently broken.  Support for this compiler
is likely to be removed in the near future.

=item *

Tests 9-11 in F<t/op/blocks.t> currently fail on Windows.
L<[perl #134295]|https://rt.perl.org/Ticket/Display.html?id=134295>

=back

=head1 Acknowledgements

Perl 5.31.2 represents approximately 4 weeks of development since Perl 5.31.1
and contains approximately 7,600 lines of changes across 190 files from 16
authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 3,100 lines of changes to 99 .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 5.31.2:

Alexandr Savca, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari
Mannsåker, David Mitchell, H.Merijn Brand, James E Keenan, Karen Etheridge,
Karl Williamson, Nicolas R., Pali, Paul Evans, Richard Leach, Steve Hay,
Svyatoslav, 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