=encoding utf8
-=for to-do
-23b7025ebc definitely needs to be summarised.
-
=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 v5.17.7
+perldelta - what is new for perl v5.17.9
=head1 DESCRIPTION
-This document describes differences between the 5.17.6 release and the 5.17.7
+This document describes differences between the 5.17.8 release and the 5.17.9
release.
-If you are upgrading from an earlier release such as 5.17.5, first read
-L<perl5176delta>, which describes differences between 5.17.5 and 5.17.6.
+If you are upgrading from an earlier release such as 5.17.7, first read
+L<perl5178delta>, which describes differences between 5.17.7 and 5.17.8.
=head1 Notice
=head1 Core Enhancements
-=head2 $&, $` and $' are no longer slow
+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 ]
+
+=head2 Interpolations now Accepted in Regular Expression Set Operations
-These three infamous variables have been redeemed and no longer slow down
-your program when used. Hence, the /p regular expression flag now does
-nothing.
+Perl v5.17.8 introduced L<regular expression set operations|perlre/(?[ ])>.
+They have now been expanded to allow the interpolation of a
+previously-compiled set into a bigger set, like this:
+
+ my $thai_or_lao = qr/\p{Thai} + \p{Lao}/;
+ ...
+ qr/(?[ \p{Digit} & $thai_or_lao ])/;
=head1 Security
=head1 Incompatible Changes
-=head2 readline() with C<$/ = \N> now reads N characters, not N bytes
-
-Previously, when reading from a stream with I/O layers such as
-C<encoding>, the readline() function, otherwise known as the C<< <> >>
-operator, would read I<N> bytes from the top-most layer. [perl #79960]
-
-Now, I<N> characters are read instead.
+XXX For a release on a stable branch, this section aspires to be:
-There is no change in behaviour when reading from streams with no
-extra layers, since bytes map exactly to characters.
+ There are no changes intentionally incompatible with 5.XXX.XXX
+ If any exist, they are bugs, and we request that you submit a
+ report. See L</Reporting Bugs> below.
-=head2 Lexical subroutine warnings have moved
-
-The warning about the use of an experimental feature emitted when lexical
-subroutines (added in 5.17.4) are used now happens when the subroutine
-itself is declared, not when the "lexical_subs" feature is activated via
-C<use feature>.
-
-This stops C<use feature ':all'> from warning, but causes
-C<my sub foo; my sub bar> to warn twice.
-
-=head2 Overridden C<glob> is now passed one argument
-
-C<glob> overrides used to be passed a magical undocumented second argument
-that identified the caller. Nothing on CPAN was using this, and it got in
-the way of a bug fix, so it was removed. If you really need to identify
-the caller, see L<Devel::Callsite> on CPAN.
+[ List each incompatible change as a =head2 entry ]
=head1 Deprecations
[ List each deprecation as a =head2 entry ]
-=head2 Lexical $_ is now deprecated
+=head2 Deprecated Modules
+
+The following modules will be removed from the core distribution in a
+future release, and should be installed from CPAN instead. Distributions
+on CPAN which require these should add them to their prerequisites. The
+core versions of these modules C<warnings> will issue a deprecation warning.
-Since it was introduced in Perl 5.10, it has caused much confusion with no
-obvious solution:
+You can silence these deprecation warnings by installing the modules
+in question from CPAN.
=over
-=item *
+=item L<Archive::Extract>
-Various modules (e.g., List::Util) expect callback routines to use the
-global $_. C<use List::Util 'first'; my $_; first { $_ == 1 } @list> does
-not work as one would expect.
+=item L<B::Lint>
-=item *
+=item L<B::Lint::Debug>
-A C<my $_> declaration earlier in the same file can cause confusing closure
-warnings.
+=item L<CPANPLUS>
-=item *
+=item L<CPANPLUS::Backend>
-The "_" subroutine prototype character allows called subroutines to access
-your lexical $_, so it is not really private after all.
+=item L<CPANPLUS::Backend::RV>
-=item *
+=item L<CPANPLUS::Config>
-Nevertheless, subroutines with a "(@)" prototype and methods cannot access
-the caller's lexical $_, unless they are written in XS.
+=item L<CPANPLUS::Config::HomeEnv>
-=item *
+=item L<CPANPLUS::Configure>
+
+=item C<CPANPLUS::Configure::Setup>
+
+=item L<CPANPLUS::Dist>
+
+=item L<CPANPLUS::Dist::Autobundle>
+
+=item L<CPANPLUS::Dist::Base>
+
+=item L<CPANPLUS::Dist::Build>
+
+=item L<CPANPLUS::Dist::Build::Constants>
+
+=item L<CPANPLUS::Dist::MM>
+
+=item L<CPANPLUS::Dist::Sample>
+
+=item L<CPANPLUS::Error>
+
+=item L<CPANPLUS::Internals>
+
+=item C<CPANPLUS::Internals::Constants>
+
+=item C<CPANPLUS::Internals::Constants::Report>
+
+=item L<CPANPLUS::Internals::Extract>
+
+=item L<CPANPLUS::Internals::Fetch>
+
+=item L<CPANPLUS::Internals::Report>
+
+=item L<CPANPLUS::Internals::Search>
+
+=item L<CPANPLUS::Internals::Source>
+
+=item L<CPANPLUS::Internals::Source::Memory>
+
+=item L<CPANPLUS::Internals::Source::SQLite>
+
+=item C<CPANPLUS::Internals::Source::SQLite::Tie>
+
+=item L<CPANPLUS::Internals::Utils>
+
+=item C<CPANPLUS::Internals::Utils::Autoflush>
+
+=item L<CPANPLUS::Module>
+
+=item L<CPANPLUS::Module::Author>
+
+=item L<CPANPLUS::Module::Author::Fake>
+
+=item L<CPANPLUS::Module::Checksums>
-But even XS routines cannot access a lexical $_ declared, not in the
-calling subroutine, but in an outer scope, iff that subroutine happened not
-to mention $_ or use any operators that default to $_.
+=item L<CPANPLUS::Module::Fake>
+
+=item C<CPANPLUS::Module::Signature>
+
+=item L<CPANPLUS::Selfupdate>
+
+=item L<CPANPLUS::Shell>
+
+=item L<CPANPLUS::Shell::Classic>
+
+=item L<CPANPLUS::Shell::Default>
+
+=item L<CPANPLUS::Shell::Default::Plugins::CustomSource>
+
+=item L<CPANPLUS::Shell::Default::Plugins::Remote>
+
+=item L<CPANPLUS::Shell::Default::Plugins::Source>
+
+=item L<Devel::InnerPackage>
+
+=item L<Log::Message>
+
+=item L<Log::Message::Config>
+
+=item L<Log::Message::Handlers>
+
+=item L<Log::Message::Item>
+
+=item L<Log::Message::Simple>
+
+=item L<Module::Pluggable>
+
+=item L<Module::Pluggable::Object>
+
+=item L<Object::Accessor>
+
+=item L<Term::UI>
+
+=item L<Term::UI::History>
=back
-=head2 Various XS-callable functions are now deprecated
-
-The following functions will be removed from a future version of Perl,
-and should not be used. With participating C compilers (e.g., gcc),
-compiling any file that uses any of these will generate a warning.
-These were not intended for public use; there are equivalent, faster,
-macros for most of them. See L<perlapi/Character classes>:
-C<is_uni_ascii>,
-C<is_uni_ascii_lc>,
-C<is_uni_blank>,
-C<is_uni_blank_lc>,
-C<is_uni_cntrl>,
-C<is_uni_cntrl_lc>,
-C<is_uni_idfirst_lc>,
-C<is_uni_space>,
-C<is_uni_space_lc>,
-C<is_uni_xdigit>,
-C<is_uni_xdigit_lc>,
-C<is_utf8_ascii>,
-C<is_utf8_blank>,
-C<is_utf8_cntrl>,
-C<is_utf8_idcont>,
-C<is_utf8_idfirst>,
-C<is_utf8_perl_space>,
-C<is_utf8_perl_word>,
-C<is_utf8_posix_digit>,
-C<is_utf8_space>,
-C<is_utf8_xdigit>.
-C<is_utf8_xidcont>,
-C<is_utf8_xidfirst>,
-C<to_uni_lower_lc>,
-C<to_uni_title_lc>,
+=head3 Deprecated Utilities
+
+The following utilities will be removed from the core distribution in a
+future release as their associated modules have been deprecated. They
+will remain available with the applicable CPAN distribution.
+
+=over
+
+=item L<cpanp>
+
+Included with L<CPANPLUS>.
+
+=item C<cpanp-run-perl>
+
+Included with L<CPANPLUS>.
+
+=item L<cpan2dist>
+
+Included with L<CPANPLUS>.
+
+=item L<pod2latex>
+
+The L<Pod::LaTeX> module was deprecated with 5.17.8.
+
+=back
+
+=head2 Five additional characters should be escaped in patterns with C</x>
+
+When a regular expression pattern is compiled with C</x>, Perl treats 6
+characters as white space to ignore, such as SPACE and TAB. However,
+Unicode recommends 11 characters be treated thusly. In preparation to
+conforming with this in a future Perl version, in the meantime, use of
+any of the missing characters will raise a deprecation warning, unless
+turned off. The five characters are:
+U+0085 NEXT LINE,
+U+200E LEFT-TO-RIGHT MARK,
+U+200F RIGHT-TO-LEFT MARK,
+U+2028 LINE SEPARATOR,
and
-C<to_uni_upper_lc>.
+U+2029 PARAGRAPH SEPARATOR.
=head1 Performance Enhancements
=item *
-Perl has a new copy-on-write mechanism that avoids the need to copy the
-internal string buffer when assigning from one scalar to another. This
-makes copying large strings appear much faster. Modifying one of the two
-(or more) strings after an assignment will force a copy internally. This
-makes it unnecessary to pass strings by reference for efficiency.
+XXX
=back
=item *
-XXX
+L<Config::Perl::V> version 0.16 has been added as a dual-lifed module.
+It provides structured data retrieval of C<perl -V> output including
+information only known to the C<perl> binary and not available via L<Config>.
=back
=item *
-L<File::DosGlob> has been upgraded from version 1.08 to 1.09. The internal
-cache of file names that it keeps for each caller is now freed when that
-caller is freed. This means
-C<< use File::DosGlob 'glob'; eval 'scalar <*>' >> no longer leaks memory.
+L<Benchmark> has been upgraded from version 1.13 to 1.14.
+
+The "too few iterations" message is now a warning on STDERR
+instead of being output on STDOUT.
+
+=item *
+
+L<Data::Dumper> has been upgraded from version 2.141 to 2.142.
+
+Additional tests were added in order to improve statement, branch, condition
+and subroutine coverage. On the basis of the coverage analysis, some of the
+internals of Dumper.pm were refactored. Almost all methods are now
+documented.
=item *
-L<File::Glob> has been upgraded from version 1.18 to 1.19. File::Glob has
-had exactly the same fix as File::DosGlob. Since it is what Perl's own
-C<glob> operator itself uses (except on VMS), this means
-C<< eval 'scalar <*>' >> no longer leaks.
+L<File::Temp> has been upgraded from version 0.22 to 0.22_90
+
+Fixes various bugs involving directory removal. Defers unlinking tempfiles if
+the initial unlink fails, which fixes problems on NFS.
=item *
-L<GDBM_File> has been upgraded from version 1.14 to 1.15. The undocumented
-optional fifth parameter to C<TIEHASH> has been removed. This was intended
-to provide control of the callback used by C<gdbm*> functions in case of
-fatal errors (such as filesystem problems), but did not work (and could
-never have worked). No code on CPAN even attempted to use it. The callback
-is now always the previous default, C<croak>. Problems on some platforms with
-how the C<C> C<croak> function is called have also been resolved.
+L<PerlIO::scalar> has been upgraded from version 0.15 to 0.16.
+
+The buffer scalar supplied may now only contain code pounts 0xFF or
+lower. [perl #109828]
=back
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.
-=head3 L<perlapi/Character classes>
+=head3 L<perlsec>
=over 4
=item *
-There are quite a few macros callable from XS modules that classify
-characters into things like alphabetic, punctuation, etc. More of these
-are now documented, including ones which work on characters whose code
-points are outside the Latin-1 range.
+A syntax error was fixed in one of illustrative examples.
=back
=item *
-XXX L<message|perldiag/"message">
+Strings with code points over 0xFF may not be mapped into in-memory file handles
=back
=item *
-L<Constant(%s): Call to &{$^H{%s}} did not return a defined value|perldiag/Constant(%s): Call to &{$^H{%s}} did not return a defined value>
-
-Constant overloading that returns C<undef> results in this error message.
-For numeric constants, it used to say "Constant(undef)". "undef" has been
-replaced with the number itself.
+The warnings for \b{ and \B{ were added in the 5.17 series; they are a
+deprecation warning which should be turned off by that category. One
+should not have to turn off regular regexp warnings as well to get rid
+of these.
=back
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]
-=head3 L<XXX>
+=head3 L<corelist>
=over 4
=item *
-XXX
+Added C<--feature> switch which lists the first version bundle of each
+named feature given.
=back
=item *
-XXX
+Added C<useversionedarchname> option to Configure
+
+When set, it includes 'api_versionstring' in 'archname'. E.g.
+x86_64-linux-5.13.6-thread-multi. It is unset by default.
+
+This feature was requested by Tim Bunce, who observed that
+INSTALL_BASE creates a library structure that does not
+differentiate by perl version. Instead, it places architecture
+specific files in "$install_base/lib/perl5/$archname". This makes
+it difficult to use a common INSTALL_BASE library path with
+multiple versions of perl.
+
+By setting -Duseversionedarchname, the $archname will be
+distinct for architecture *and* API version, allowing mixed use of
+INSTALL_BASE.
+
+=item *
+
+Configure will honour the external C<MAILDOMAIN> environment variable, if set.
+
+=item *
+
+Both C<META.yml> and C<META.json> files are now included in the distribution.
=back
=item *
-XXX
+Enable perl core tests to pass when locale support is not available.
+
+use L<locale> - this will now die if $Config{d_setlocale} is not true.
+All tests that use L<locale> will skip if $Config{d_setlocale} is not true.
+This enables us to pass tests on Android which uses ICU instead of locales.
=back
=head2 Discontinued Platforms
+XXX List any platforms that this version of perl no longer compiles on.
+
=over 4
-=item BeOS
+=item XXX-some-platform
-Support for BeOS has been removed.
+XXX
=back
=over 4
-=item XXX-some-platform
+=item VMS
-XXX
+The character set for Extended Filename Syntax (EFS) is now enabled by default on
+VMS. Among other things, this provides better handling of dots in directory names,
+multiple dots in filenames,and spaces in filenames. To obtain the old behavior,
+set the logical name C<DECC$EFS_CHARSET> to C<DISABLE>.
=back
=item *
-SvUPGRADE() is no longer an expression. Originally this macro (and its
-underlying function, sv_upgrade()) were documented as boolean, although
-in reality they always croaked on error and never returned false. In 2005
-the documentation was updated to specify a void return value, but
-SvUPGRADE() was left always returning 1 for backwards compatibility. This
-has now been removed, and SvUPGRADE() is now a statement with no return
-value.
-
-So this is now a syntax error:
-
- if (!SvUPGRADE(sv)) { croak(...); }
-
-If you have code like that, simply replace it with
-
- SvUPGRADE(sv);
-
-or to to avoid compiler warnings with older perls, possibly
-
- (void)SvUPGRADE(sv);
-
-=item *
-
-Perl has a new copy-on-write mechanism that allows any SvPOK scalar to be
-upgraded to a copy-on-write scalar. A reference count on the string buffer
-is stored in the string buffer itself.
-
-This breaks a few XS modules by allowing copy-on-write scalars to go
-through code paths that never encountered them before.
+Synonyms for the misleadingly named C<av_len()> has been created:
+C<av_top_index()> and C<av_tindex>. All three of these return the
+number of the highest index in the array, not the number of elements it
+contains. (The name C<av_top> which was introduced in Perl v.5.17.8 has
+been removed.)
-This behaviour can still be disabled by running F<Configure> with
-B<-Accflags=-DPERL_NO_COW>. This option will probably be removed in Perl
-5.20.
-
-=item *
-
-Copy-on-write no longer uses the SvFAKE and SvREADONLY flags. Hence,
-SvREADONLY indicates a true read-only SV.
-
-Use the SvIsCOW macro (as before) to identify a copy-on-write scalar.
-
-=item *
-
-C<PL_sawampersand> is now a constant. The switch this variable provided
-(to enable/disable the pre-match copy depending on whether C<$&> had been
-seen) has been removed and replaced with copy-on-write, eliminating a few
-bugs.
-
-The previous behaviour can still be enabled by running F<Configure> with
-B<-Accflags=-DPERL_SAWAMPERSAND>.
-
-=item *
-
-PL_glob_index is gone.
+XXX
=back
=item *
-C<sort {undef} ...> under fatal warnings no longer crashes. It started
-crashing in Perl 5.16.
-
-=item *
-
-Stashes blessed into each other
-(C<bless \%Foo::, 'Bar'; bless \%Bar::, 'Foo'>) no longer result in double
-frees. This bug started happening in Perl 5.16.
-
-=item *
-
-Numerous memory leaks have been fixed, mostly involving fatal warnings and
-syntax errors.
-
-=item *
-
-Lexical constants (C<my sub answer () { 42 }>) no longer cause double
-frees.
-
-=item *
-
-Constant subroutine redefinition warns by default, but lexical constants
-were accidentally exempt from default warnings. This has been corrected.
-
-=item *
-
-Some failed regular expression matches such as C<'f' =~ /../g> were not
-resetting C<pos>. Also, "match-once" patterns (C<m?...?g>) failed to reset
-it, too, when invoked a second time [perl #23180].
-
-=item *
-
-Accessing C<$&> after a pattern match now works if it had not been seen
-before the match. I.e., this applies to C<${'&'}> (under C<no strict>) and
-C<eval '$&'>. The same applies to C<$'> and C<$`> [perl #4289].
-
-=item *
-
-Several bugs involving C<local *ISA> and C<local *Foo::> causing stale
-MRO caches have been fixed.
-
-=item *
-
-Defining a subroutine when its typeglob has been aliased no longer results
-in stale method caches. This bug was introduced in Perl 5.10.
-
-=item *
-
-Localising a typeglob containing a subroutine when the typeglob's package
-has been deleted from its parent stash no longer produces an error. This
-bug was introduced in Perl 5.14.
-
-=item *
-
-Under some circumstances, C<local *method=...> would fail to reset method
-caches upon scope exit.
-
-=item *
-
-C</[.foo.]/> is no longer an error, but produces a warning (as before) and
-is treated as C</[.fo]/> [perl #115818].
-
-=item *
-
-C<goto $tied_var> now calls FETCH before deciding what type of goto
-(subroutine or label) this is.
-
-=item *
-
-Renaming packages through glob assignment
-(C<*Foo:: = *Bar::; *Bar:: = *Baz::>) in combination with C<m?...?> and
-C<reset> no longer makes threaded builds crash.
+-DPERL_GLOBAL_STRUCT builds now free the global struct B<after>
+they've finished using it.
=item *
-An earlier release in the 5.17.x series could crash if user code prevented
-_charnames from loading via C<$INC{'_charnames.pm'}++>.
+A trailing '/' on a path in @INC will no longer have an additional '/' appended.
=back
XXX Generate this with:
- perl Porting/acknowledgements.pl v5.17.6..HEAD
+ perl Porting/acknowledgements.pl v5.17.8..HEAD
=head1 Reporting Bugs