=encoding utf8
-=for todo
-5204593b74eb sv.c: Make sv_pvn_force_flags guard against SV_UNDEF_RETURNS_NULL.
-28333232a1c7 Don’t localise CopSTASH(&PL_compiling) in newCONSTSUB
-c947b31cf142 Do away with stashpv_hvname_match
-d0279c7ce493 Fix bad assertions in pp_ctl.c:pp_caller
-9a62b98f29d2 gv.c: Don’t ENTER/LEAVE unnecessarily
-ee1b3814fd18 gv.c: Remove mro_method_changed_in() from gv_init
-a3c74922a705 Rmv mro_method_changed_in call on stub upgraded to const
-7ad40bcb0a19 Don’t call mro_method_changed_in after newCONSTSUB
-
=head1 NAME
-perldelta - what is new for perl v5.17.1
+[ 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 v5.17.3
=head1 DESCRIPTION
-This document describes differences between the 5.17.0 release and
-the 5.17.1 release.
+This document describes differences between the 5.17.2 release and the 5.17.3
+release.
-If you are upgrading from an earlier release such as 5.16.0, first read
-L<perl5170delta>, which describes differences between 5.16.0 and
-5.17.0.
+If you are upgrading from an earlier release such as 5.17.1, first read
+L<perl5172delta>, which describes differences between 5.17.1 and 5.17.2.
-=head1 Core Enhancements
+=head1 Notice
-=head2 More CORE:: subs
+XXX Any important notices here
-Several more built-in functions have been added as subroutines to the
-CORE:: namespace, namely, those non-overridable keywords that can be
-implemented without custom parsers: C<defined>, C<delete>, C<exists>,
-C<glob>, C<pos>, C<protoytpe>, C<scalar>, C<split>, C<study>, and C<undef>.
+=head1 Core Enhancements
-As some of these have prototypes, C<prototype('CORE::...')> has been
-changed to not make a distinction between overridable and non-overridable
-keywords. This is to make C<prototype('CORE::pos')> consistent with
-C<prototype(&CORE::pos)>.
+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.
-=head1 Incompatible Changes
+[ List each enhancement as a =head2 entry ]
-=head2 C</(?{})/> and C</(??{}> have been heavily reworked.
+=head2 Computed Labels
-The implementation of this feature has been almost completely rewritten.
-Although its main intent is to fix bugs, some behaviours, especially
-related to the scope of lexical variables, will have changed. This is
-described more fully in the L</Selected Bug Fixes> section.
+The loop controls C<next>, C<last> and C<redo>, and the special C<dump>
+operator, now allow arbitrary expressions to be used to compute labels at
+run time. Previously, any argument that was not a constant was treated as
+the empty string.
-=head2 C<\N{BELL}> now refers to U+1F514 instead of U+0007
+=head1 Security
-Unicode 6.0 reused the name "BELL" for a different code point than it
-traditionally had meant. Since Perl v5.14, use of this name still
-referred to U+0007, but would raise a deprecated warning. Now, "BELL"
-refers to U+1F514, and the name for U+0007 is "ALERT". All the
-functions in L<charnames> have been correspondingly updated.
+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.
-=head2 Alphanumeric operators must now be separated from the closing
-delimiter of regular expressions
+[ List each security issue as a =head2 entry ]
-You may no longer write something like:
+=head1 Incompatible Changes
- m/a/and 1
+[ List each incompatible change as a =head2 entry ]
-Instead you must write
+=head2 C<$ENV{foo}=undef> deletes value from environ, like C<delete $ENV{foo}>
- m/a/ and 1
+This facilitates use of C<local()> with C<%ENV> entries. In previous
+versions of Perl, C<undef> was converted to the empty string.
-with whitespace separating the operator from the closing delimiter of
-the regular expression. Not having whitespace has resulted in a
-deprecated warning since Perl v5.14.0.
+=head2 Defined values stored in environment are forced to byte strings
-=head2 C<require> dies for unreadable files
+A value stored in an environment variable has always been stringified. In
+this release, it is converted to be only a byte string. First, it is forced
+to be a only a string. Then if the string is utf8 and the equivalent of
+C<utf8::downgrade()> works, that result is used; otherwise, the equivalent of
+C<utf8::encode()> is used, and a warning is issued about wide characters
+(L</Diagnostics>).
-When C<require> encounters an unreadable file, it now dies. It used to
-ignore the file and continue searching the directories in @INC
-[perl #113422].
+=head2 C<given> now aliases the global C<$_>
-=head2 Upgrade to the Unicode 6.2 beta
+Instead of assigning to an implicit lexical C<$_>, C<given> now makes the
+global C<$_> an alias for its argument, just like C<foreach>. However, it
+still uses lexical C<$_> if there is lexical C<$_> in scope (again, just like
+C<foreach>).
-Unicode 6.2 is proposing some changes that may very well break some CPAN
-modules. The timing of this nicely coincides with Perl's being early in the
-release cycle. This commit takes the current beta 6.2, adds the proposed
-changes that aren't yet in it, and subtracts the changes that would affect \X
-processing, as those turn out to have errors, and may have to be rethought.
-Unicode has been notified of these problems.
+=head1 Deprecations
-This will allow us to gather data as to whether or not the proposed changes
-cause us problems. These will be presented to Unicode to aid in their final
-decision as to whether or not to go forward with the changes.
+XXX Any deprecated features, syntax, modules etc. should be listed here. In
+particular, deprecated modules should be listed here even if they are listed as
+an updated module in the L</Modules and Pragmata> section.
-These changes will be replaced by the final version of Unicode 6.2 before
-5.18.0 is released.
+[ List each deprecation as a =head2 entry ]
=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 *
-The C<x> repetition operator is now folded to a single constant at compile
-time if called in scalar context with constant operands and no parentheses
-around the left operand.
+XXX
=back
=head1 Modules and Pragmata
-=head2 Updated 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>, which prints stub
+entries to STDOUT. Results can be pasted in place of the '=head2' entries
+below. 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.
-=over 4
+[ Within each section, list entries as a =item entry ]
-=item *
+=head2 New Modules and Pragmata
-L<Archive::Extract> has been upgraded from version 0.58 to 0.60.
-
-Work around an edge case on Linux with Busybox's unzip.
+=over 4
=item *
-L<Archive::Tar> has been upgraded from version 1.82 to 1.88.
-
-ptar now supports -T option and dashless options [rt.cpan.org #75473],
-[rt.cpan.org #75475].
+XXX
-Auto-encode filenames marked as UTF-8 [rt.cpan.org #75474].
+=back
-Don't use tell on IO::Zlib handles [rt.cpan.org #64339].
+=head2 Updated Modules and Pragmata
-Don't try to C<chown> on symlinks.
+=over 4
=item *
-L<attributes> has been upgraded from version 0.19 to 0.20.
-
-No visible changes.
+L<B> has been upgraded from version 1.36 to 1.37. All C<CVf_*> and C<GVf_*>
+and more SV-related flag values are now provided as constants in the C<B::>
+namespace and available for export. The default export list has not changed.
=item *
-L<autodie> has been upgraded from version 2.10 to 2.11.
-
-No visible changes.
+L<B::Concise> has been upgraded from version 0.91 to 0.92. The C<-nobanner>
+option has been fixed, and C<format>s can now be dumped. When passed a sub
+name to dump, it will check also to see whether it is the name of a format. If
+a sub and a format share the same name, it will dump both.
=item *
-L<B> has been upgraded from version 1.35 to 1.36.
-
-C<B::COP::stashlen> has been replaced with C<B::COP::stashoff>.
-
-C<B::COP::stashpv> now supports UTF8 package names and embedded NULs.
+L<B::Deparse> has been upgraded from version 1.15 to 1.16. It now deparses
+loop controls with the correct precedence, and multiple statements in a
+C<format> line are also now deparsed correctly.
=item *
-L<B::Deparse> has been upgraded from version 1.14 to 1.15.
-
-Avoid warning when run under C<perl -w>.
+L<Compress::Raw::Bzip2> has been upgraded from version 2.05201 to 2.055. The
+misuse of Perl's "magic" API has been fixed.
=item *
-L<Class::Struct> has been upgraded from version 0.63 to 0.64.
-
-The constructor now respects overridden accessor methods [perl #29230].
+L<Compress::Raw::Zlib> has been upgraded from version 2.05401 to 2.056. The
+misuse of Perl's "magic" API has been fixed.
=item *
-L<Compress::Raw::Bzip2> has been upgraded from version 2.048 to 2.052.
-
-No visible changes.
+L<Compress::Zlib> has been upgraded from version 2.052 to 2.055.
+C<compress()>, C<uncompress()>, C<memGzip()> and C<memGunzip()> have been
+speeded up by making parameter validation more efficient.
=item *
-L<Compress::Raw::Zlib> has been upgraded from version 2.048 to 2.054.
-
-Upgrade bundled zlib to version 1.2.7.
-
-Fix build failures on Irix, Solaris, and Win32, and also when building as C++
-[rt.cpan.org #69985], [rt.cpan.org #77030], [rt.cpan.org #75222].
+L<Data::Dumper> has been upgraded from version 2.135_06 to 2.135_07. It has
+been optimized to only build a seen-scalar hash as necessary, thereby speeding
+up serialization drastically.
=item *
-L<CPAN::Meta> has been upgraded from version 2.120630 to 2.120921.
-
-Split L<CPAN::Meta::Requirements> into its own distribution.
+L<Devel::Peek> has been upgraded from version 1.08 to 1.09. The only change
+has been to the test script, to account for changes to some flags in perl's
+internals.
=item *
-L<CPAN::Meta::Requirements> has been upgraded from version 2.120630 to 2.122.
-
-Treat undef requirements to C<from_string_hash> as 0 (with a warning).
-
-Added C<requirements_for_module> method.
+L<Encode> has been upgraded from version 2.44 to 2.47. The Mac alias x-mac-ce
+has been added, and various bugs have been fixed in Encode::Unicode,
+Encode::UTF7 and Encode::GSM0338.
=item *
-L<CPAN::Meta::YAML> has been upgraded from version 0.007 to 0.008.
-
-No visible changes.
+L<Module::Build> has been upgraded from version 0.40 to 0.4002. A minor bug
+fix allows markup to be used around the leading "Name" in a POD "abstract"
+line, and some documentation improvements have been made.
=item *
-L<CPANPLUS> has been upgraded from version 0.9121 to 0.9130.
-
-Allow adding F<blib/script> to PATH.
-
-Save the history between invocations of the shell.
-
-Handle multiple C<makemakerargs> and C<makeflags> arguments better.
-
-Use C<File::HomeDir> when available, and provide C<PERL5_CPANPLUS_HOME> to
-override the autodetection.
-
-Always re-fetch CHECKSUMS if C<fetchdir> is set.
+L<Module::CoreList> has been upgraded from version 2.69 to 2.70. Version
+information is now stored as a delta, which greatly reduces the size of the
+F<CoreList.pm> file.
=item *
-L<Digest::MD5> has been upgraded from version 2.51 to 2.52.
-
-Fix Digest::Perl::MD5 OO fallback [rt.cpan.org #66634].
+L<Module::Load::Conditional> has been upgraded from version 0.50 to 0.54.
+Various enhancements include the new use of Module::Metadata.
=item *
-L<DynaLoader> has been upgraded from version 1.14 to 1.15.
-
-This is due to a minor code change in the XS for the VMS implementation.
+L<Module::Metadata> has been upgraded from version 1.000009 to 1.000010. The
+creation of a Module::Metadata object for a typical module file has been sped
+up by about 40%.
=item *
-L<ExtUtils::CBuilder> has been upgraded from version 0.280206 to 0.280208.
-
-Manifest files are now correctly embedded for those versions of VC++ which
-make use of them. [perl #111782, #111798].
+L<Module::Pluggable> has been upgraded from version 4.0 to 4.2. Amongst other
+changes, triggers are now allowed on events, which gives a powerful way to
+modify behaviour.
=item *
-L<File::DosGlob> has been upgraded from version 1.07 to 1.08.
-
-There are no visible changes, only minor internal refactorings.
+L<Pod::Simple> has been upgraded from version 3.20 to 3.23. Numerous
+improvements have been made, mostly to Pod::Simple::XHTML, which also has a
+compatibility change: the C<codes_in_verbatim> option is now disabled by
+default. See F<cpan/Pod-Simple/ChangeLog> for the full details.
=item *
-L<File::Fetch> has been upgraded from version 0.32 to 0.34.
-
-No visible changes.
+L<re> has been upgraded from version 0.21 to 0.22. Single character [class]es
+like C</[s]/> or C</[s]/i> are now optimized as if they did not have the
+brackets, i.e. C</s/> or C</s/i>.
=item *
-L<File::Spec::Unix> has been upgraded from version 3.39_02 to 3.39_03.
-
-C<abs2rel> could produce incorrect results when given two relative paths or
-the root directory twice [perl #111510].
+L<Socket> has been upgraded from version 2.002 to 2.003. Constants and
+functions required for IP multicast source group membership have been added.
=item *
-L<Filter::Util::Call> has been upgraded from version 1.40 to 1.45.
-
-No visible changes.
+L<Storable> has been upgraded from version 2.37 to 2.38. It can now freeze
+and thaw vstrings correctly. This causes a slight incompatible change in
+the storage format, so the format version has increased to 2.9.
=item *
-L<HTTP::Tiny> has been upgraded from version 0.017 to 0.022.
-
-Add SSL verification features [github #6], [github #9].
-
-Include the final URL in the response hashref.
-
-Add C<local_address> option.
+L<Sys::Syslog> has been upgraded from version 0.29 to 0.30. An issue with
+C<POSIX::strftime()> on Windows and a build problem on Haiku-OS have been
+resolved, and <getservbyname()> is no longer called when the port is specified.
=item *
-L<IO> has been upgraded from version 1.25_06 to 1.25_07.
-
-C<sync()> can now be called on read-only file handles [perl #64772].
+L<Time::Local> has been upgraded from version 1.2000 to 1.2300. Seconds values
+greater than 59 but less than 60 no longer cause C<timegm()> and C<timelocal()>
+to croak.
=item *
-L<IPC::Cmd> has been upgraded from version 0.76 to 0.78.
-
-Use C<POSIX::_exit> instead of C<exit> in C<run_forked> [rt.cpan.org #76901].
+L<Unicode::UCD> has been upgraded from version 0.44 to 0.45. This has been
+modified slightly for reasons of perl internal use only.
=item *
-L<Memoize> has been upgraded from version 1.02 to 1.03.
-
-Fix the C<MERGE> cache option.
+L<Win32> has been upgraded from version 0.44 to 0.45. New APIs have been added
+for getting and setting the current code page.
=item *
-L<Module::Build> has been upgraded from version 0.39_01 to 0.40.
-
-Fixed bug where modules without C<$VERSION> might have a version of '0' listed
-in 'provides' metadata, which will be rejected by PAUSE.
-
-Fixed bug in PodParser to allow numerals in module names.
-
-Fixed bug where giving arguments twice led to them becoming arrays, resulting
-in install paths like F<ARRAY(0xdeadbeef)/lib/Foo.pm>.
-
-=item *
+L<Win32CORE> has been upgraded from version 0.02 to 0.03. The use of
+PERL_NO_GET_CONTEXT here has resulted in smaller machine code.
-L<Module::Load::Conditional> has been upgraded from version 0.46 to 0.50.
+=back
-Fix use of C<requires> on perls installed to a path with spaces.
+=head1 Documentation
-=item *
+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>.
-L<Object::Accessor> has been upgraded from version 0.42 to 0.44.
+=head2 New Documentation
-No visible changes.
+XXX Changes which create B<new> files in F<pod/> go here.
-=item *
+=head3 L<XXX>
-L<Params::Check> has been upgraded from version 0.32 to 0.36.
+XXX Description of the purpose of the new file here
-No visible changes.
+=head2 Changes to Existing Documentation
-=item *
+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.
-L<Parse::CPAN::Meta> has been upgraded from version 1.4402 to 1.4404.
+=head3 L<perlfunc>, L<perlop>
-No visible changes.
+=over 4
=item *
-L<PerlIO::mmap> has been upgraded from version 0.010 to 0.011.
+Loop control verbs (C<dump>, C<goto>, C<next>, C<last> and C<redo>) have
+always had the same precedence as assignment operators, but this was never
+documented until now.
-No visible changes.
+=back
-=item *
+=head1 Diagnostics
-L<PerlIO::via::QuotedPrint> has been upgraded from version 0.06 to 0.07.
+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>.
-No visible changes.
+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.
-=item *
+=head2 New Diagnostics
-L<Pod::Html> has been upgraded from version 1.15_02 to 1.16.
+XXX Newly added diagnostic messages go under here, separated into New Errors
+and New Warnings
-The option C<--libpods> has been reinstated. It is deprecated, and its use
-does nothing other than issue a warning that it is no longer supported.
+=head3 New Errors
-Since the HTML files generated by pod2html claim to have a utf-8 charset,
-actually write the files out using utf-8 [perl #111446].
+=over 4
=item *
-L<POSIX> has been upgraded from version 1.30 to 1.31.
-
-No visible changes.
+L<Unterminated delimiter for here document|perldiag/"Unterminated delimiter for here document">
-=item *
-
-L<re> has been upgraded from version 0.19 to 0.20.
+This message now occurs when a here document label has an initial quotation
+mark but the final quotation mark is missing.
-See note about C<op_comp> in the L</Internal Changes> section below.
+This replaces a bogus and misleading error message about not finding the
+label itself [perl #114104].
-=item *
+=back
-L<Safe> has been upgraded from version 2.31_01 to 2.33_01.
+=head3 New Warnings
-XXX where do these dev versions come from?
+=over 4
=item *
-L<Scalar::Util> has been upgraded from version 1.23 to version 1.25.
+L<Wide character in setenv|perldiag/"Wide character in %s">
-Fix an overloading issue with C<sum>.
+Attempts to put wide characters into environment variables via C<%ENV> now
+provoke this warning.
-C<first> and C<reduce> now check the callback first (so C<&first(1)> is
-disallowed).
+=back
-Fix C<tainted> on magical values [rt.cpan.org #55763].
+=head2 Changes to Existing Diagnostics
-Fix C<sum> on previously magical values [rt.cpan.org #61118].
+XXX Changes (i.e. rewording) of diagnostic messages go here
-Fix reading past the end of a fixed buffer [rt.cpan.org #72700].
+=over 4
=item *
-L<Search::Dict> has been upgraded from version 1.04 to 1.07.
-
-No longer require C<stat> on filehandles.
+XXX Describe change here
-Use C<fc> for casefolding.
-
-=item *
-
-L<Storable> has been upgraded from version 2.35 to 2.36.
+=back
-No visible changes.
+=head1 Utility Changes
-=item *
+XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
+Most of these are built within the directories F<utils> and F<x2p>.
-L<Term::ANSIColor> has been upgraded from version 3.01 to 3.02.
+[ List utility changes as a =head3 entry for each utility and =item
+entries for each change
+Use L<XXX> with program names to get proper documentation linking. ]
-Add support for italics.
+=head3 L<XXX>
-Improve error handling.
+=over 4
=item *
-L<Test::Harness> has been upgraded from version 3.23 to 3.25.
-
-Fix glob semantics on Win32 [rt.cpan.org #49732].
+XXX
-Don't use Win32::GetShortPathName when calling perl [rt.cpan.org #47890].
+=back
-Ignore -T when reading shebang [rt.cpan.org #64404].
+=head1 Configuration and Compilation
-Handle the case where we don't know the wait status of the test more
-gracefully.
+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.
-Make the test summary 'ok' line overrideable so that it can be changed to a
-plugin to make the output of prove idempotent.
+[ List changes as a =item entry ].
-Don't run world-writable files.
+=over 4
=item *
-L<Unicode::UCD> has been upgraded from version 0.43 to 0.44.
-
-This adds a function L<all_casefolds()|Unicode::UCD/all_casefolds()>
-that returns all the casefolds.
+XXX
=back
-=head1 Documentation
+=head1 Testing
-=head2 Changes to Existing Documentation
+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.
-=head3 L<perlfaq>
+[ List each test improvement as a =item entry ]
=over 4
=item *
-L<perlfaq> has been synchronised with version 5.0150040 from C<CPAN>.
+XXX
=back
-=head3 L<perlcheat>
+=head1 Platform Support
-=over 4
+XXX Any changes to platform support should be listed in the sections below.
-=item *
+[ Within the sections, list each platform as a =item entry with specific
+changes as paragraphs below it. ]
-L<perlcheat> has been reorganized, and a few new sections were added.
+=head2 New Platforms
-=back
+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.
-=head1 Diagnostics
+=over 4
-=head2 Removals of Diagnostics
+=item XXX-some-platform
-=over 4
+XXX
-=item *
+=back
-The "Runaway prototype" warning that occurs in bizarre cases has been
-removed as being unhelpful and inconsistent.
+=head2 Discontinued Platforms
-=item *
+XXX List any platforms that this version of perl no longer compiles on.
-The "Not a format reference" error has been removed, as the only case in
-which it could be triggered was a bug.
+=over 4
-=item *
+=item XXX-some-platform
-The "Unable to create sub named %s" error has been removed for the same
-reason.
+XXX
=back
-=head1 Platform Support
-
=head2 Platform-Specific Notes
-XXX note fails on win2k and vms
+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 Win32
+=item XXX-some-platform
-C<link> on Win32 now attempts to set C<$!> to more appropriate values
-based on the Win32 API error code. [perl #112272]
-
-Perl no longer mangles the environment block, e.g. when launching a new
-sub-process, when the environment contains non-ASCII characters. Known
-problems still remain, however, when the environment contains characters
-outside of the current ANSI codepage (e.g. see the item about Unicode in
-C<%ENV> in L<http://perl5.git.perl.org/perl.git/blob/HEAD:/Porting/todo.pod>).
-[perl #113536]
+XXX
=back
=head1 Internal Changes
-=over 4
-
-=item *
-
-The C<study> function was made a no-op in 5.16. It was simply disabled via
-a C<return> statement; the code was left in place. Now the code supporting
-what C<study> used to do has been removed.
+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.
-=item *
-
-Under threaded perls, there is no longer a separate PV allocated for every
-COP to store its package name (C<< cop->stashpv >>). Instead, there is an
-offset (C<< cop->stashoff >>) into the new C<PL_stashpad> array, which
-holds stash pointers.
-
-=item *
+[ List each change as a =item entry ]
-In the pluggable regex API, the C<regexp_engine> struct has acquired a new
-field C<op_comp>, which is currently just for perl's internal use, and
-should be initialised to NULL by other regex plugin modules.
+=over 4
=item *
-A new function C<alloccoptash> has been added to the API, but is considered
-experimental. See L<perlapi>.
+XXX
=back
=head1 Selected Bug Fixes
-=over 4
+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>.
-=item *
-
-The implementation of code blocks in regular expressions, such as C<(?{})>
-and C<(??{})> has been heavily reworked to eliminate a whole slew of bugs.
-The main user-visible changes are:
+[ List each fix as a =item entry ]
=over 4
=item *
-Code blocks within patterns are now parsed in the same pass as the
-surrounding code; in particular it is no longer necessary to have balanced
-braces: this now works:
-
- /(?{ $x='{' })/
-
-This means that this error message is longer generated:
-
- Sequence (?{...}) not terminated or not {}-balanced in regex
-
-but a new error may be seen:
-
- Sequence (?{...}) not terminated with ')'
-
-In addition, literal code blocks within run-time patterns are only
-compiled once, at perl compile-time:
-
- for my $p (...) {
- # this 'FOO' block of code is compiled once,
- # at the same time as the surrounding 'for' loop
- /$p{(?{FOO;})/;
- }
+C<\w> now matches the code points U+200C (ZERO WIDTH NON-JOINER) and
+U+200D (ZERO WIDTH JOINER). C<\W> no longer matches these. This change
+is because Unicode corrected their definition of what C<\w> should match.
=item *
-Lexical variables are now sane as regards scope, recursion and closure
-behaviour. In particular, C</A(?{B})C/> behaves (from a closure viewpoint)
-exactly like C</A/ && do { B } && /C/>, while C<qr/A(?{B})C/> is like
-C<sub {/A/ && do { B } && /C/}>. So this code now works how you might
-expect, creating three regexes that match 0, 1, and 2:
-
- for my $i (0..2) {
- push @r, qr/^(??{$i})$/;
- }
- "1" =~ $r[1]; # matches
+C<dump LABEL> no longer leaks its label.
=item *
-The C<use re 'eval'> pragma is now only required for code blocks defined
-at runtime; in particular in the following, the text of the C<$r> pattern is
-still interpolated into the new pattern and recompiled, but the individual
-compiled code-blocks within C<$r> are reused rather than being recompiled,
-and C<use re 'eval'> isn't needed any more:
-
- my $r = qr/abc(?{....})def/;
- /xyz$r/;
+Constant folding no longer changes the behaviour of functions like C<stat()>
+and C<truncate()> that can take either filenames or handles.
+C<stat 1 ? foo : bar> nows treats its argument as a file name (since it is
+an arbitrary expression), rather than the handle "foo".
=item *
-Flow control operators no longer crash. Each code block runs in a new
-dynamic scope, so C<next> etc. will not see any enclosing loops and
-C<caller> will not see any calling subroutines. C<return> returns a value
-from the code block, not from any enclosing subroutine.
+C<truncate FOO, $len> no longer falls back to treating "FOO" as a file name
+if the filehandle has been deleted. This was broken in Perl 5.16.0.
=item *
-Perl normally caches the compilation of run-time patterns, and doesn't
-recompile if the pattern hasn't changed; but this is now disabled if
-required for the correct behaviour of closures; for example:
-
- my $code = '(??{$x})';
- for my $x (1..3) {
- # recompile to see fresh value of $x each time
- $x =~ /$code/;
- }
-
+Subroutine redefinitions after sub-to-glob and glob-to-glob assignments no
+longer cause double frees or panic messages.
=item *
-The C</msix> and C<(?msix)> etc. flags are now propagated into the return
-value from C<(??{})>; this now works:
-
- "AB" =~ /a(??{'b'})/i;
+C<s///> now turns vstrings into plain strings when performing a
+substitution, even if the resulting string is the same (C<s/a/a/>).
=item *
-Warnings and errors will appear to come from the surrounding code (or for
-run-time code blocks, from an eval) rather than from an C<re_eval>:
-
- use re 'eval'; $c = '(?{ warn "foo" })'; /$c/;
- /(?{ warn "foo" })/;
-
-formerly gave:
-
- foo at (re_eval 1) line 1.
- foo at (re_eval 2) line 1.
-
-and now gives:
-
- foo at (eval 1) line 1.
- foo at /some/prog line 2.
-
-=back
-
-=item *
-
-Perl now works as well as can be expected on all releases of Unicode so
-far. In v5.16, it worked on Unicodes 6.0 and 6.1, but there were
-various bugs for earlier releases; the older the release the more
-problems.
-
-=item *
-
-C<vec> no longer produces "uninitialized" warnings in lvalue context
-[perl #9423].
-
-=item *
-
-An optimisation involving fixed strings in regular expressions could cause
-a severe performance penalty in edge cases. This has been fixed
-[perl #76546].
-
-=item *
-
-In certain cases, including empty subpatterns within a regular expression (such
-as C<(?:)> or C<(?:|)>) could disable some optimizations. This has been fixed.
-
-=item *
-
-The "Can't find an opnumber" message that C<prototype> produces when passed
-a string like "CORE::nonexistent_keyword" now passes UTF8 and embedded
-NULs through unchanged [perl #97478].
+Prototype mismatch warnings no longer erroneously treat constant subs as
+having no prototype when they actually have "".
=item *
-C<prototype> now treats magical variables like C<$1> the same way as
-non-magical variables when checking for the CORE:: prefix, instead of
-treating them as subroutine names.
+Constant subroutines and forward declarations no longer prevent prototype
+mismatch warnings from omitting the sub name.
=item *
-Under threaded perls, a runtime code block in a regular expression could
-corrupt the package name stored in the op tree, resulting in bad reads
-in C<caller>, and possibly crashes [perl #113060].
+C<undef> on a subroutine now clears call checkers.
=item *
-Referencing a closure prototype (C<\&{$_[1]}> in an attribute handler for a
-closure) no longer results in a copy of the subroutine (or assertion
-failures on debugging builds).
+The C<ref> operator started leaking memory on blessed objects in Perl
+5.16.0. This has been fixed [perl #114340].
=item *
-C<eval '__PACKAGE__'> now returns the right answer on threaded builds if
-the current package has been assigned over (as in
-C<*ThisPackage:: = *ThatPackage::>) [perl #78742].
+C<use> no longer tries to parse its arguments as a statement, making
+C<use constant { () };> a syntax error [perl #114222].
=item *
-If a package is deleted by code that it calls, it is possible for C<caller>
-to see a stack frame belonging to that deleted package. C<caller> could
-crash if the stash's memory address was reused for a scalar and a
-substitution was performed on the same scalar [perl #113486].
+On debugging builds, "uninitialized" warnings inside formats no longer
+cause assertion failures.
=item *
-C<UNIVERSAL::can> no longer treats its first argument differently
-depending on whether it is a string or number internally.
+On debugging builds, subroutines nested inside formats no longer cause
+assertion failures [perl #78550].
=item *
-C<open> with "<&" for the mode checks to see whether the third argument is
-a number, in determining whether to treat it as a file descriptor or a
-handle name. Magical variables like C<$1> were always failing the numeric
-check and being treated as handle names.
+C<print $x> and C<sub { print $x }->()> now always produce the same output.
+It was possible for the latter to refuse to close over $x if the variable
+was not active; e.g., if it was defined outside a currently-running named
+subroutine.
=item *
-C<warn>'s handling of magical variables (C<$1>, ties) has undergone several
-fixes. FETCH is only called once now on a tied argument or a tied C<$@>
-[perl #97480]. Tied variables returning objects that stringify as "" are
-no longer ignored. A tied C<$@> that happened to return a reference the
-I<previous> time is was used is no longer ignored.
+Similarly, C<print $x> and C<print eval '$x'> now produce the same output.
+This also allows "my $x if 0" variables to be seen in the debugger
+[perl #114018].
=item *
-C<warn ""> now treats C<$@> with a number in it the same way, regardless of
-whether it happened via C<$@=3> or C<$@="3">. It used to ignore the
-former. Now it appends "\t...caught", as it has always done with
-C<$@="3">.
+Formats called recursively no longer stomp on their own lexical variables,
+but each recursive call has its own set of lexicals.
=item *
-Numeric operators on magical variables (e.g., S<C<$1 + 1>>) used to use
-floating point operations even where integer operations were more appropriate,
-resulting in loss of accuracy on 64-bit platforms [perl #109542].
+Attempting to free an active format or the handle associated with it no
+longer results in a crash.
=item *
-Unary negation no longer treats a string as a number if the string happened
-to be used as a number at some point. So, if C<$x> contains the string "dogs",
-C<-$x> returns "-dogs" even if C<$y=0+$x> has happened at some point.
+Format parsing no longer gets confused by braces, semicolons and
+low-precedence operators. It used to be possible to use braces as format
+delimiters (instead of C<=> and C<.>), but only sometimes. Semicolons and
+low-precedence operators in format argument lines no longer confuse the
+parser into ignoring the line's return value. In format argument lines,
+braces can now be used for anonymous hashes, instead of being treated
+always as C<do> blocks.
=item *
-In Perl 5.14, C<-'-10'> was fixed to return "10", not "+10". But magical
-variables (C<$1>, ties) were not fixed till now [perl #57706].
+Formats can now be nested inside code blocks in regular expressions and
+other quoted constructs (C</(?{...})/> and C<qq/${...}/>) [perl #114040].
=item *
-Unary negation now treats strings consistently, regardless of the internal
-UTF8 flag.
-
-=item *
-
-A regression introduced in Perl v5.16.0 involving
-C<tr/I<SEARCHLIST>/I<REPLACEMENTLIST>/> has been fixed. Only the first
-instance is supposed to be meaningful if a character appears more than
-once in C<I<SEARCHLIST>>. Under some circumstances, the final instance
-was overriding all earlier ones. [perl #113584]
-
-=item *
-
-Regular expressions like C<qr/\87/> previously silently inserted a NUL
-character, thus matching as if it had been written C<qr/\00087/>. Now it
-matches as if it had been written as C<qr/87/>, with a message that the
-sequence C<"\8"> is unrecognized.
-
-=item *
-
-C<__SUB__> now works in special blocks (BEGIN, END, etc.).
-
-=item *
-
-Thread creation on Windows could theoretically result in a crash if done
-inside a BEGIN block. It still does not work properly, but it no longer
-crashes [perl #111610].
-
-=item *
-
-C<\&{''}> (with the empty string) now autovivifies a stub like any other
-sub name, and no longer produces the "Unable to create sub" error
-[perl #94476].
+Formats are no longer created after compilation errors.
=back
=head1 Known Problems
-=over 4
+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.
-=item *
+[ List each fix as a =item entry ]
-On VMS, Module::Build still fails its test suite.
+=over 4
=item *
-On Win32, several tests fail intermittently, and may hang unless STDERR is
-redirected.
+XXX
=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 v5.17.0..HEAD
+ perl Porting/acknowledgements.pl v5.17.2..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 http://rt.perl.org/perlbug/ . There may also be
-information at http://www.perl.org/ , the Perl Home Page.
+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
+http://rt.perl.org/perlbug/ . 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 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
+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.
+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<Changes> file for an explanation of how to view exhaustive details on
+what changed.
The F<INSTALL> file for how to build Perl.
https://perl5.git.perl.org / perl5.git / blobdiff