Deprecate wide chars in logical string ops

[perl5.git] / pod / perldelta.pod

=encoding utf8

=head1 NAME

[ this is a template for a new perldelta file.  Any text flagged as XXX needs
to be processed before release. ]

perldelta - what is new for perl v5.23.6

=head1 DESCRIPTION

This document describes differences between the 5.23.5 release and the 5.23.6
release.

If you are upgrading from an earlier release such as 5.23.4, first read
L<perl5235delta>, which describes differences between 5.23.4 and 5.23.5.

=head1 Notice

XXX Any important notices here

=head1 Core Enhancements

XXX New core language features go here.  Summarize user-visible core language
enhancements.  Particularly prominent performance optimisations could go
here, but most should go in the L</Performance Enhancements> section.

[ List each enhancement as a =head2 entry ]

=head1 Security

XXX Any security-related notices go here.  In particular, any security
vulnerabilities closed should be noted here rather than in the
L</Selected Bug Fixes> section.

[ List each security issue as a =head2 entry ]

=head1 Incompatible Changes

=head2 Some regular expression patterns that had runtime errors now
don't compile at all

This should have been in the perldelta for 5.23.4, but was omitted.

Almost all Unicode properties using the C<\p{}> and C<\P{}> regular
expression pattern constructs are now checked for validity at pattern
compilation time, and invalid ones will cause the program to not
compile.  In earlier releases, this check was often deferred until run
time.  Whenever an error check is moved from run- to compile time,
erroneous code is caught 100% of the time, whereas before it would only
get caught if and when the offending portion actually gets executed,
which for unreachable code might be never.

=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

=item XXX

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

[ List each other deprecation as a =head2 entry ]

=head2 Using code points above the platform's C<IV_MAX> is now
deprecated

Unicode defines code points in the range C<0..0x10FFFF>.  Some standards
at one time defined them up to 2**31 - 1, but Perl has allowed them to
be as high as anything that will fit in a word on the platform being
used.  However, use of those above the platform's C<IV_MAX> is broken in
some constructs, notably C<tr///>, regular expression patterns involving
quantifiers, and in some arithmetic and comparison operations, such as
being the upper limit of a loop.  Now the use of such code points raises
a deprecation warning, unless that warning category is turned off.
C<IV_MAX> is typically 2**31 -1 on 32-bit platforms, and 2**63-1 on
64-bit ones.

=head2 Doing bitwise operations on strings containing code points above
0xFF is deprecated

The string bitwise operators treat their operands as strings of bytes,
and values beyond 0xFF are nonsensical in this context.  To operate on
encoded bytes, first encode the strings.  To operate on code points'
numeric values, use C<split> and C<map ord>.  In the future, this
warning will be replaced by an exception.

=head1 Performance Enhancements

XXX Changes which enhance performance without changing behaviour go here.
There may well be none in a stable release.

[ List each enhancement as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Modules and Pragmata

XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
go here.  If Module::CoreList is updated, generate an initial draft of the
following sections using F<Porting/corelist-perldelta.pl>.  A paragraph summary
for important changes should then be added by hand.  In an ideal world,
dual-life modules would have a F<Changes> file that could be cribbed.

[ Within each section, list entries as a =item entry ]

=head2 New Modules and Pragmata

=over 4

=item *

XXX

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Data::Dumper> has been upgraded from version 2.158 to 2.159.

This adds a "Trailingcomma" option, which when enabled adds a trailing comma
after the last element of dumped arrays and hashes that would otherwise be
followed immediately by a line break.  [perl #126813]

=item *

L<DynaLoader> has been upgraded from version 1.36 to 1.37.

Fixed an else nesting issue in dynamic loading support for OS/390 (and
similar systems) that was introduced in 1.36.

=item *

L<utf8> has been upgraded from 1.17 to 1.18.

Partly reverted a micro-optimization to F<lib/utf_heavy.pl> that
caused self-recursion when it was loaded with C<${^ENCODING}> set.
[perl #126593]

=item *

The modules L<sigtrap>, L<DB>, and the perl debugger could have under
rare circumstances, without you expecting it, output containing raw
control characters.  This has been fixed.

=back

=head2 Removed Modules and Pragmata

=over 4

=item *

XXX

=back

=head1 Documentation

XXX Changes to files in F<pod/> go here.  Consider grouping entries by
file and be sure to link to the appropriate page, e.g. L<perlfunc>.

=head2 New Documentation

XXX Changes which create B<new> files in F<pod/> go here.

=head3 L<XXX>

XXX Description of the purpose of the new file here

=head2 Changes to Existing Documentation

XXX Changes which significantly change existing files in F<pod/> go here.
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.

=head3 L<XXX>

=over 4

=item *

XXX Description of the change here

=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>.

XXX New or changed warnings emitted by the core's C<C> code go here.  Also
include any changes in L<perldiag> that reconcile it to the C<C> code.

=head2 New Diagnostics

XXX Newly added diagnostic messages go under here, separated into New Errors
and New Warnings

=head3 New Errors

=over 4

=item *

L<message|perldiag/"Invalid number '%s' for -C option.">

(F) You supplied a number to the -C option that either has extra leading
zeroes or overflows perl's unsigned integer representation.


=back

=head3 New Warnings

=over 4

=item *

XXX L<message|perldiag/"message">

=back

=head2 Changes to Existing Diagnostics

XXX Changes (i.e. rewording) of diagnostic messages go here

=over 4

=item *

XXX Describe change here

=back

=head1 Utility Changes

XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
Most of these are built within the directory F<utils>.

[ List utility changes as a =head2 entry for each utility and =item
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]

=head2 L<XXX>

=over 4

=item *

XXX

=back

=head1 Configuration and Compilation

XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
go here.  Any other changes to the Perl build process should be listed here.
However, any platform-specific changes should be listed in the
L</Platform Support> section, instead.

[ List changes as a =item entry ].

=over 4

=item *

F<make_ext.pl> is no longer inappropriately silent.  This was caused
by an operator precedence error introduced in 5.23.4.

=back

=head1 Testing

XXX Any significant changes to the testing of a freshly built perl should be
listed here.  Changes which create B<new> files in F<t/> go here as do any
large changes to the testing harness (e.g. when parallel testing was added).
Changes to existing files in F<t/> aren't worth summarizing, although the bugs
that they represent may be covered elsewhere.

[ List each test improvement as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Platform Support

XXX Any changes to platform support should be listed in the sections below.

[ Within the sections, list each platform as a =item entry with specific
changes as paragraphs below it. ]

=head2 New Platforms

XXX List any platforms that this version of perl compiles on, that previous
versions did not.  These will either be enabled by new files in the F<hints/>
directories, or new subdirectories and F<README> files at the top level of the
source tree.

=over 4

=item XXX-some-platform

XXX

=back

=head2 Discontinued Platforms

XXX List any platforms that this version of perl no longer compiles on.

=over 4

=item XXX-some-platform

XXX

=back

=head2 Platform-Specific Notes

XXX List any changes for specific platforms.  This could include configuration
and compilation changes or changes in portability/compatibility.  However,
changes within modules for platforms should generally be listed in the
L</Modules and Pragmata> section.

=over 4

=item EBCDIC platforms, such as z/OS

UTF-EBCDIC is like UTF-8, but for EBCDIC platforms.  It now has been
extended so that it can represent code points up to 2 ** 64 - 1 on
platforms with 64-bit words.  This brings it into parity with UTF-8.
This enhancement requires an incompatible change to the representation
of code points in the range 2 ** 30 to 2 ** 31 -1 (the latter was the
previous maximum representable code point).  This means that a file that
contains one of these code points, written out with previous versions of
perl cannot be read in, without conversion, by a perl containing this
change.  We do not believe any such files are in existence, but if you
do have one, submit a ticket at L<mailto:perlbug@perl.org>, and we will
write a conversion script for you.

=back

=head1 Internal Changes

XXX Changes which affect the interface available to C<XS> code go here.  Other
significant internal changes for future core maintainers should be noted as
well.

[ List each change as a =item entry ]

=over 4

=item *

Perl core code and the threads extension have been annotated so that
if Perl is configured to use threads, during compile-time clang (3.6
or later) will warn about suspicious uses of mutexes.
See L<http://clang.llvm.org/docs/ThreadSafetyAnalysis.html> for more
information.

=back

=head1 Selected Bug Fixes

XXX Important bug fixes in the core language are summarized here.  Bug fixes in
files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.

[ List each fix as a =item entry ]

=over 4

=item *

C</...\G/> no longer crashes on utf8 strings. When C<\G> is a fixed number
of characters from the start of the regex, perl needs to count back that
many characters from the current C<pos()> position and start matching from
there. However, it was counting back bytes rather than characters, which
could lead to panics on utf8 strings.

=item *

In some cases operators that return integers would return negative
integers as large positive integers.  [perl #126635]

=item *

The pipe() operator would assert for DEBUGGING builds instead of
producing the correct error message.  The condition asserted on is
detected and reported on correctly without the assertions, so the
assertions were removed.  [perl #126480]

=item *

In some cases, failing to parse a here-doc would attempt to use freed
memory.  This was caused by a pointer not being restored correctly.
[perl #126443]

=back

=head1 Known Problems

XXX Descriptions of platform agnostic bugs we know we can't fix go here.  Any
tests that had to be C<TODO>ed for the release would be noted here.  Unfixed
platform specific bugs also go here.

[ List each fix as a =item entry ]

=over 4

=item *

XXX

=back

=head1 Errata From Previous Releases

=over 4

=item *

XXX Add anything here that we forgot to add, or were mistaken about, in
the perldelta of a previous release.

=back

=head1 Obituary

XXX If any significant core contributor has died, we've added a short obituary
here.

=head1 Acknowledgements

XXX Generate this with:

  perl Porting/acknowledgements.pl v5.23.5..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
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 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