path: root/pod/perldelta.pod

=encoding utf8

=head1 NAME

perldelta - what is new for perl v5.21.3

=head1 DESCRIPTION

This document describes differences between the 5.21.2 release and the 5.21.3
release.

If you are upgrading from an earlier release such as 5.21.1, first read
L<perl5212delta>, which describes differences between 5.21.1 and 5.21.2.

=head1 Core Enhancements

=head2 C<defined(@array = LIST)> is no longer fatal

In 5.21.1, C<defined(@array)> was made fatal.  This has been relaxed
to not die if the argument is assigning to an array.

=head2 Floating point parsing has been improved

Parsing and printing of floating point values has been improved.

As a completely new feature, hexadecimal floating point literals
(like 0x1.23p-4)  are now supported, and they can be output with
C<printf %a>.

=head1 Security

=head2 The L<Safe> module could allow outside packages to be replaced

Critical bugfix: outside packages could be replaced.  L<Safe> has
been patched to 2.38 to address this.

=head1 Incompatible Changes

=head2 S<C<use UNIVERSAL '...'>> is now a fatal error

Importing functions from C<UNIVERSAL> has been deprecated since v5.12, and
is now a fatal error.  S<C<"use UNIVERSAL">> without any arguments is still
allowed.

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<B::Debug> has been upgraded from version 1.19 to 1.21.

=item *

L<Config::Perl::V> has been upgraded from version 0.20 to 0.22.

=item *

L<CPAN::Meta> has been upgraded from version 2.141520 to 2.142060.

=item *

L<CPAN::Meta::Requirements> has been upgraded from version 2.125 to 2.126.

=item *

L<ExtUtils::CBuilder> was moved from F<dist> to F<cpan>.

=item *

L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280217.

=item *

L<ExtUtils::Install> was moved from F<dist> to F<cpan>.

=item *

L<ExtUtils::Manifest> has been upgraded from version 1.64 to 1.65.
It was also moved from F<dist> to F<cpan>.

=item *

L<HTTP::Tiny> has been upgraded from version 0.043 to 0.047.

=item *

L<IPC::Open3> has been upgraded from version 1.17 to 1.18.

=item *

L<Module::CoreList> has been upgraded from version 5.021002 to 5.021003.

=item *

L<Opcode> has been upgraded from version 1.27 to 1.28.

=item *

L<perl5db.pl> has been upgraded from version 1.45 to 1.46.

=item *

L<perlfaq> has been upgraded from version 5.0150044 to 5.0150045.

=item *

L<POSIX> has been upgraded from version 1.41 to 1.42.

=item *

L<Safe> has been upgraded from version 2.37 to 2.38.

=item *

L<Socket> has been upgraded from version 2.014 to 2.015.

=item *

L<Sys::Hostname> has been upgraded from version 1.18 to 1.19

=item *

L<UNIVERSAL> has been upgraded from version 1.11 to 1.12.

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=head3 L<perlexperiment>

=over 4

=item *

Added reference to L<feature>.

=back

=head3 L<perlguts>

=over 4

=item *

Details on C level symbols and libperl.t added.

=back

=head3 L<perlhacktips>

=over 4

=item *

Recommended replacements for tmpfile, atoi, strtol, and strtoul added.

=back

=head3 L<perlop>

=over 4

=item *

ASCII v. EBCDIC clarifications added.

=back

=head3 L<perlsec>

=over 4

=item *

Comments added on algorithmic complexity and tied hashes.

=back

=head3 L<perlvms>

=over 4

=item *

Updated documentation on environment and shell interaction in VMS.

=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 New Diagnostics

=head3 New Errors

=over 4

=item *

L<Hexadecimal float: internal error|perldiag/"Hexadecimal float: internal error">

(F) Something went horribly bad in hexadecimal float handling.

=item *

L<Hexadecimal float: unsupported long double format|perldiag/"Hexadecimal float: unsupported long double format">

(F) You have configured Perl to use long doubles but
the internals of the long double format are unknown,
therefore the hexadecimal float output is impossible.

=back

=head3 New Warnings

=over 4

=item *

L<Hexadecimal float: exponent overflow|perldiag/"Hexadecimal float: exponent overflow">

(W overflow) The hexadecimal floating point has larger exponent
than the floating point supports.

=item *

L<Hexadecimal float: exponent underflow|perldiag/"Hexadecimal float: exponent underflow">

(W overflow) The hexadecimal floating point has smaller exponent
than the floating point supports.

=item *

L<Hexadecimal float: mantissa overflow|perldiag/"Hexadecimal float: mantissa overflow">

(W overflow) The hexadecimal floating point literal had more bits in
the mantissa (the part between the 0x and the exponent, also known as
the fraction or the significand) than the floating point supports.

=item *

L<Hexadecimal float: precision loss|perldiag/"Hexadecimal float: precision loss">

(W overflow) The hexadecimal floating point had internally more
digits than could be output.  This can be caused by unsupported
long double formats, or by 64-bit integers not being available
(needed to retrieve the digits under some configurations).

=back

=head2 Changes to Existing Diagnostics

=over 4

=item *

C<require> with no argument or undef used to warn about a Null filename; now
it dies with C<Missing or undefined argument to require>.

=back

=head1 Configuration and Compilation

=over 4

=item *

MurmurHash64A and MurmurHash64B can now be configured as the internal hash
function.

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item Android

Build support has been improved for cross-compiling in general and for
Android in particular.

=item Solaris

C<c99> options have been cleaned up, hints look for C<solstudio>
as well as C<SUNWspro>, and support for native C<setenv> has been added.

=item VMS

C<finite>, C<finitel>, and C<isfinite> detection has been added to
C<configure.com>, environment handling has had some minor changes, and
a fix for legacy feature checking status.

=item Windows

C<%I64d> is now being used instead of C<%lld> for MinGW.

=back

=head1 Internal Changes

=over 4

=item *

Added L<perlapi/sync_locale>.
Changing the program's locale should be avoided by XS code.  Nevertheless,
certain non-Perl libraries called from XS, such as C<Gtk> do so.  When this
happens, Perl needs to be told that the locale has changed.  Use this function
to do so, before returning to Perl.

=item *

Added L<perlapi/grok_atou> as a safer replacement for atoi and strtol.

=back

=head1 Selected Bug Fixes

=over 4

=item *

Failing to compile C<use Foo> in an eval could leave a spurious
C<BEGIN> subroutine definition, which would produce a "Subroutine
BEGIN redefined" warning on the next use of C<use>, or other C<BEGIN>
block.  [perl #122107]

=item *

C<method { BLOCK } ARGS> syntax now correctly parses the arguments if they
begin with an opening brace.  [perl #46947]

=item *

External libraries and Perl may have different ideas of what the locale is.
This is problematic when parsing version strings if the locale's numeric
separator has been changed.  Version parsing has been patched to ensure
it handles the locales correctly.  [perl #121930]

=item *

A bug has been fixed where zero-length assertions and code blocks inside of a
regex could cause C<pos> to see an incorrect value.  [perl #122460]

=back

=head1 Acknowledgements

Perl 5.21.3 represents approximately 4 weeks of development since Perl 5.21.2
and contains approximately 21,000 lines of changes across 250 files from 25
authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 18,000 lines of changes to 160 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community
of users and developers. The following people are known to have contributed the
improvements that became Perl 5.21.3:

Aaron Crane, Abigail, Alberto Simões, Andy Dougherty, Brian Fraser, Chad
Granum, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker,
Daniel Dragan, David Mitchell, Father Chrysostomos, H.Merijn Brand, James E
Keenan, Jan Dubois, Jarkko Hietaniemi, Karen Etheridge, Karl Williamson, Lukas
Mai, Peter Martini, Rafael Garcia-Suarez, syber, Tony Cook, Vladimir Marek,
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 articles recently
posted to the comp.lang.perl.misc newsgroup and the perl bug database at
https://rt.perl.org/ .  There may also be information at
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 please send it
to perl5-security-report@perl.org.  This points to a closed subscription
unarchived mailing list, which includes all the core committers, who will be
able to help assess the impact of issues, figure out a resolution, and help
co-ordinate the release of patches to mitigate or fix the problem across all
platforms on which Perl is supported.  Please only use this address for
security issues in the Perl core, not for modules independently distributed on
CPAN.

=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