path: root/pod/perldelta.pod

=encoding utf8

=head1 NAME

perldelta - what is new for perl v5.19.8

=head1 DESCRIPTION

This document describes differences between the 5.19.7 release and the 5.19.8
release.

If you are upgrading from an earlier release such as 5.19.6, first read
L<perl5197delta>, which describes differences between 5.19.6 and 5.19.7.

=head1 Core Enhancements

=head2 New C<\p{Unicode}> regular expression pattern property

This is a synonym for C<\p{Any}> and matches the set of Unicode-defined
code points 0 - 0x10FFFF.

=head1 Incompatible Changes

=head2 C<do> can no longer be used to call subroutines

The C<do SUBROUTINE(LIST)> form has resulted in a deprecation warning
since Perl v5.0.0, and is now a syntax error.

=head2 C<\p{}>, C<\P{}> matching has changed for non-Unicode code
points.

C<\p{}> and C<\P{}> are defined by Unicode only on Unicode-defined code
points (C<U+0000> through C<U+10FFFF>).  Their behavior on matching
these legal Unicode code points is unchanged, but there are changes for
code points C<0x110000> and above.  Previously, Perl treated the result
of matching C<\p{}> and C<\P{}> against these as C<undef>, which
translates into "false".  For C<\P{}>, this was then complemented into
"true".  A warning was supposed to be raised when this happened.
However, various optimizations could prevent the warning, and the
results were often counter-intuitive, with both a match and its seeming
complement being false.  Now all non-Unicode code points are treated as
typical unassigned Unicode code points.  This generally is more
Do-What-I-Mean.  A warning is raised only if the results are arguably
different from a strict Unicode approach, and from what Perl used to do.
Code that needs to be strictly Unicode compliant can make this warning
fatal, and then Perl always raises the warning.

Details are in L<perlunicode/Beyond Unicode code points>.

=head2 C<\p{All}> has been expanded to match all possible code points

The Perl-defined regular expression pattern element C<\p{All}>, unused
on CPAN, used to match just the Unicode code points; now it matches all
possible code points; that is, it is equivalent to C<qr/./s>.  Thus
C<\p{All}> is no longer synonymous with C<\p{Any}>, which continues to
match just the Unicode code points, as Unicode says it should.

=head1 Deprecations

XXX Any deprecated features, syntax, modules etc. should be listed here.

=head2 Module removals

XXX Remove this section if inapplicable.

The following modules will be removed from the core distribution in a
future release, and will at that time need to be installed from CPAN.
Distributions on CPAN which require these modules will need to list them as
prerequisites.

The core versions of these modules will now issue C<"deprecated">-category
warnings to alert you to this fact.  To silence these deprecation warnings,
install the modules in question from CPAN.

Note that these are (with rare exceptions) fine modules that you are encouraged
to continue to use.  Their disinclusion from core primarily hinges on their
necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
not usually on concerns over their design.

=over

XXX Note that deprecated modules should be listed here even if they are listed
as an updated module in the L</Modules and Pragmata> section.

=back

=head1 Modules and Pragmata

=head2 New Modules and Pragmata

=over 4

=item *

L<IO::Socket::IP> has been (tentatively) added to core at version 0.26.

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<perl5db.pl> has been upgraded from version 1.42 to 1.43

Fix a crash in tab completion, where available. [perl #120827]

The debugger tests no longer open two handles to the same output file,
making them more robust. [perl #118817]

=item *

L<base> has been upgraded from version 2.20 to 2.21.

The stricter load failure tests added in 2.20 now allow for
C<${^LAST_FH}> being set.

=item *

L<constant> has been upgraded from version 1.30 to 1.31.

=item *

L<DynaLoader> has been upgraded from version 1.22 to 1.24.

=item *

L<Encode> has been upgraded from version 2.55 to 2.57.

UTF-8 is no longer used in the C source (which some compilers didn't like), and
some POD errors have been fixed in the documentation.

=item *

L<Errno> has been upgraded from version 1.20_01 to 1.20_02.

=item *

L<ExtUtils::CBuilder> has been upgraded from version 0.280212 to 0.280213.

=item *

L<ExtUtils::MakeMaker> has been upgraded from version 6.84 to 6.86.

=item *

L<File::Copy> has been upgraded from version 2.28 to 2.29.

=item *

L<Hash::Util::FieldHash> has been upgraded from version 1.13 to 1.14.

=item *

L<inc::latest> has been upgraded from version 0.4203 to 0.4204.
NOTE: L<inc::latest> is deprecated and may be removed from a future version of
Perl.

=item *

L<IO::Socket::UNIX> has been upgraded from version 1.25 to 1.26.

Removed a warning about an ancient behaviour change and filled out the
SYNOPSIS. [perl #120981]

=item *

The libnet module collection has been upgraded from version 1.23 to 1.24.

The handling of CRLF characters in L<Net::FTP> has been fixed.

=item *

L<List::Util> has been upgraded from version 1.35 to 1.36.

=item *

L<Module::Build> has been upgraded from version 0.4203 to 0.4204.
NOTE: L<Module::Build> is deprecated and may be removed from a future version
of Perl.

=item *

L<Module::CoreList> has been upgraded from version 3.02 to 3.04.

=item *

L<Module::Load> has been upgraded from version 0.24 to 0.28.

=item *

L<Module::Load::Conditional> has been upgraded from version 0.58 to 0.60.

=item *

L<Perl::OSType> has been upgraded from version 1.006 to 1.007.

=item *

L<PerlIO::encoding> has been upgraded from version 0.17 to 0.18.

=item *

L<Pod::Perldoc> has been upgraded from version 3.20 to 3.21.

=item *

L<POSIX> has been upgraded from version 1.37 to 1.38_01.

=item *

L<Scalar::Util> has been upgraded from version 1.35 to 1.36.

=item *

L<threads::shared> has been upgraded from version 1.45 to 1.46.

=item *

L<Time::Piece> has been upgraded from version 1.24 to 1.27.

=item *

L<Unicode::UCD> has been upgraded from version 0.55 to 0.57.

=item *

L<version> has been upgraded from version 0.9904 to 0.9907.

=item *

L<warnings> has been upgraded from version 1.20 to 1.21.

=item *

L<XSLoader> has been upgraded from version 0.16 to 0.17.

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=over 4

=item *

L<perlunicode> has been updated to reflect C<Bidi_Class> changes in Unicode
6.3.

=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>.

=head3 New Warnings

=over 4

=item *

%s on a reference is now experimental

The "auto-deref" feature is now experimental.

Starting in v5.14.0, it was possible to use push, pop, keys, and other
built-in functions not only on aggregate types, but on references to
them.  The feature was not deployed to its original intended
specification, and now may become redundant to postfix dereferencing.
It has always been categorized as an experimental feature, and in
v5.20.0 is carries a warning as such.

Warnings will now be issued at compile time when these operations are
detected.

  no if $] >= 5.01908, warnings => "experimental::autoderef";

Consider, though, replacing the use of these features, as they may
change behavior again before becoming stable.

=item *

L<Matched non-Unicode code point 0x%X against Unicode property; may not be portable|perldiag/"Matched non-Unicode code point 0x%X against Unicode property; may not be portable">.
This replaces the message "Code point 0x%X is not Unicode, all \p{}
matches fail; all \P{} matches succeed".

=back

=head1 Utility Changes

=head3 L<perlbug>

=over 4

=item *

F<perlbug> now has a C<-p> option for attaching patches with a bug report.

=item *

F<perlbug> now does input in the encoding of the current locale and
output raw.

=back

=head1 Configuration and Compilation

=over 4

=item *

Distinct library basenames with C<d_libname_unique>.

When compiling perl with this option, the library files for XS modules are
named something "unique" -- for example, Hash/Util/Util.so becomes
Hash/Util/PL_Hash__Util.so.  This behavior is similar to what currently
happens on VMS, and serves as groundwork for the Android port.

=item *

C<sysroot> option to indicate the logical root directory under gcc and clang.

When building with this option set, both Configure and the compilers search
for all headers and libraries under this new sysroot, instead of /.

This is a huge time saver if cross-compiling, but can also help
on native builds if your toolchain's files have non-standard locations.

=back

=head1 Platform Support

=over 4

=item *

Code related to supporting C<sfio> has been removed.

Perl 5.004 added support to use the native API of C<sfio>, AT&T's Safe/Fast
I/O library. This code still built with v5.8.0, albeit with many regression
tests failing, but was inadvertently broken before the v5.8.1 release,
meaning that it has not worked on any version of Perl released since then.
In over a decade we have received no bug reports about this, hence it is clear
that no-one is using this functionality on any version of Perl that is still
supported to any degree.

=back

=head2 Platform-Specific Notes

=over 4

=item Cygwin

recv() on a connected handle would populate the returned sender
address with whatever happened to be in the working buffer.  recv()
now uses a workaround similar to the Win32 recv() wrapper and returns
an empty string when recvfrom(2) doesn't modify the supplied address
length. [perl #118843]

=back

=head1 Internal Changes

=over 4

=item newATTRSUB is now a macro

The public API newATTRSUB was previously a macro to the private
function Perl_newATTRSUB. Function Perl_newATTRSUB has been removed. newATTRSUB
is now macro to a different internal function.

=item Changes in warnings raised by C<utf8n_to_uvchr()>

This bottom level function decodes the first character of a UTF-8 string
into a code point.  It is accessible to C<XS> level code, but it's
discouraged from using it directly.  There are higher level functions
that call this that should be used instead, such as
L<perlapi/utf8_to_uvchr_buf>.  For completeness though, this documents
some changes to it.  Now, tests for malformations are done before any
tests for other potential issues.  One of those issues involves code
points so large that they have never appeared in any official standard
(the current standard has scaled back the highest acceptable code point
from earlier versions).  It is possible (though not done in CPAN) to
warn and/or forbid these code points, while accepting smaller code
points that are still above the legal Unicode maximum.  The warning
message for this now includes the code point if representable on the
machine.  Previously it always displayed raw bytes, which is what it
still does for non-representable code points.

=back

=head1 Selected Bug Fixes

=over 4

=item *

In v5.19.6, C<do CORE()> was inadvertently changed from being interpreted
as do-file (i.e., C<do +CORE()>) to do-sub (i.e., C<&CORE()>).  It has now
been changed back.

=item *

v5.19.7 inadvertently caused freed scalars to be passed to subroutines in
@INC if it contained multiple subs.  This has been fixed. [perl #120657]

=item *

Individually-tied elements of @INC (as in C<tie $INC[0]...>) are now
handled correctly.  Formerly, whether a sub returned by such a tied element
would be treated as a sub depended on whether a FETCH had occurred
previously.

=item *

C<getc> on a byte-sized handle after the same C<getc> operator had been
used on a utf8 handle used to treat the bytes as utf8, resulting in erratic
behavior (e.g., malformed UTF-8 warnings).

=item *

An initial C<{> at the beginning of a format argument line was always
interpreted as the beginning of a block prior to v5.18.  In Perl v5.18, it
started being treated as an ambiguous token.  The parser would guess
whether it was supposed to be an anonymous hash constructor or a block
based on the contents.  Now the previous behavious has been restored.
[perl #119973]

=item *

In Perl v5.18 C<undef *_; goto &sub> and C<local *_; goto &sub> started
crashing.  This has been fixed. [perl #119949]

=back

=head1 Acknowledgements

XXX Generate this with:

  perl Porting/acknowledgements.pl v5.19.7..HEAD

=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