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-=encoding utf8
-
-=head1 NAME
-
-perl5120delta - what is new for perl v5.12.0
-
-=head1 DESCRIPTION
-
-This document describes differences between the 5.10.0 release and the
-5.12.0 release.
-
-Many of the bug fixes in 5.12.0 are already included in the 5.10.1
-maintenance release.
-
-You can see the list of those changes in the 5.10.1 release notes
-(L<perl5101delta>).
-
-
-=head1 Core Enhancements
-
-=head2 New C<package NAME VERSION> syntax
-
-This new syntax allows a module author to set the $VERSION of a namespace
-when the namespace is declared with 'package'. It eliminates the need
-for C<our $VERSION = ...> and similar constructs. E.g.
-
- package Foo::Bar 1.23;
- # $Foo::Bar::VERSION == 1.23
-
-There are several advantages to this:
-
-=over
-
-=item *
-
-C<$VERSION> is parsed in exactly the same way as C<use NAME VERSION>
-
-=item *
-
-C<$VERSION> is set at compile time
-
-=item *
-
-C<$VERSION> is a version object that provides proper overloading of
-comparison operators so comparing C<$VERSION> to decimal (1.23) or
-dotted-decimal (v1.2.3) version numbers works correctly.
-
-=item *
-
-Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
-
-=item *
-
-As it requires VERSION to be a numeric literal or v-string
-literal, it can be statically parsed by toolchain modules
-without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
-
-=back
-
-It does not break old code with only C<package NAME>, but code that uses
-C<package NAME VERSION> will need to be restricted to perl 5.12.0 or newer
-This is analogous to the change to C<open> from two-args to three-args.
-Users requiring the latest Perl will benefit, and perhaps after several
-years, it will become a standard practice.
-
-
-However, C<package NAME VERSION> requires a new, 'strict' version
-number format. See L<"Version number formats"> for details.
-
-
-=head2 The C<...> operator
-
-A new operator, C<...>, nicknamed the Yada Yada operator, has been added.
-It is intended to mark placeholder code that is not yet implemented.
-See L<perlop/"Yada Yada Operator">.
-
-=head2 Implicit strictures
-
-Using the C<use VERSION> syntax with a version number greater or equal
-to 5.11.0 will lexically enable strictures just like C<use strict>
-would do (in addition to enabling features.) The following:
-
- use 5.12.0;
-
-means:
-
- use strict;
- use feature ':5.12';
-
-=head2 Unicode improvements
-
-Perl 5.12 comes with Unicode 5.2, the latest version available to
-us at the time of release. This version of Unicode was released in
-October 2009. See L<http://www.unicode.org/versions/Unicode5.2.0> for
-further details about what's changed in this version of the standard.
-See L<perlunicode> for instructions on installing and using other versions
-of Unicode.
-
-Additionally, Perl's developers have significantly improved Perl's Unicode
-implementation. For full details, see L</Unicode overhaul> below.
-
-=head2 Y2038 compliance
-
-Perl's core time-related functions are now Y2038 compliant. (It may not mean much to you, but your kids will love it!)
-
-=head2 qr overloading
-
-It is now possible to overload the C<qr//> operator, that is,
-conversion to regexp, like it was already possible to overload
-conversion to boolean, string or number of objects. It is invoked when
-an object appears on the right hand side of the C<=~> operator or when
-it is interpolated into a regexp. See L<overload>.
-
-=head2 Pluggable keywords
-
-Extension modules can now cleanly hook into the Perl parser to define
-new kinds of keyword-headed expression and compound statement. The
-syntax following the keyword is defined entirely by the extension. This
-allow a completely non-Perl sublanguage to be parsed inline, with the
-correct ops cleanly generated.
-
-See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core
-source distribution also includes a new module
-L<XS::APItest::KeywordRPN>, which implements reverse Polish notation
-arithmetic via pluggable keywords. This module is mainly used for test
-purposes, and is not normally installed, but also serves as an example
-of how to use the new mechanism.
-
-Perl's developers consider this feature to be experimental. We may remove
-it or change it in a backwards-incompatible way in Perl 5.14.
-
-=head2 APIs for more internals
-
-The lowest layers of the lexer and parts of the pad system now have C
-APIs available to XS extensions. These are necessary to support proper
-use of pluggable keywords, but have other uses too. The new APIs are
-experimental, and only cover a small proportion of what would be
-necessary to take full advantage of the core's facilities in these
-areas. It is intended that the Perl 5.13 development cycle will see the
-addition of a full range of clean, supported interfaces.
-
-Perl's developers consider this feature to be experimental. We may remove
-it or change it in a backwards-incompatible way in Perl 5.14.
-
-=head2 Overridable function lookup
-
-Where an extension module hooks the creation of rv2cv ops to modify the
-subroutine lookup process, this now works correctly for bareword
-subroutine calls. This means that prototypes on subroutines referenced
-this way will be processed correctly. (Previously bareword subroutine
-names were initially looked up, for parsing purposes, by an unhookable
-mechanism, so extensions could only properly influence subroutine names
-that appeared with an C<&> sigil.)
-
-=head2 A proper interface for pluggable Method Resolution Orders
-
-As of Perl 5.12.0 there is a new interface for plugging and using method
-resolution orders other than the default linear depth first search.
-The C3 method resolution order added in 5.10.0 has been re-implemented as
-a plugin, without changing its Perl-space interface. See L<perlmroapi> for
-more information.
-
-
-
-=head2 C<\N> experimental regex escape
-
-Perl now supports C<\N>, a new regex escape which you can think of as
-the inverse of C<\n>. It will match any character that is not a newline,
-independently from the presence or absence of the single line match
-modifier C</s>. It is not usable within a character class. C<\N{3}>
-means to match 3 non-newlines; C<\N{5,}> means to match at least 5.
-C<\N{NAME}> still means the character or sequence named C<NAME>, but
-C<NAME> no longer can be things like C<3>, or C<5,>.
-
-This will break a L<custom charnames translator|charnames/CUSTOM
-TRANSLATORS> which allows numbers for character names, as C<\N{3}> will
-now mean to match 3 non-newline characters, and not the character whose
-name is C<3>. (No name defined by the Unicode standard is a number,
-so only custom translators might be affected.)
-
-Perl's developers are somewhat concerned about possible user confusion
-with the existing C<\N{...}> construct which matches characters by their
-Unicode name. Consequently, this feature is experimental. We may remove
-it or change it in a backwards-incompatible way in Perl 5.14.
-
-=head2 DTrace support
-
-Perl now has some support for DTrace. See "DTrace support" in F<INSTALL>.
-
-=head2 Support for C<configure_requires> in CPAN module metadata
-
-Both C<CPAN> and C<CPANPLUS> now support the C<configure_requires>
-keyword in the F<META.yml> metadata file included in most recent CPAN
-distributions. This allows distribution authors to specify configuration
-prerequisites that must be installed before running F<Makefile.PL>
-or F<Build.PL>.
-
-See the documentation for C<ExtUtils::MakeMaker> or C<Module::Build> for
-more on how to specify C<configure_requires> when creating a distribution
-for CPAN.
-
-=head2 C<each>, C<keys>, C<values> are now more flexible
-
-The C<each>, C<keys>, C<values> function can now operate on arrays.
-
-=head2 C<when> as a statement modifier
-
-C<when> is now allowed to be used as a statement modifier.
-
-=head2 C<$,> flexibility
-
-The variable C<$,> may now be tied.
-
-=head2 // in when clauses
-
-// now behaves like || in when clauses
-
-=head2 Enabling warnings from your shell environment
-
-You can now set C<-W> from the C<PERL5OPT> environment variable
-
-=head2 C<delete local>
-
-C<delete local> now allows you to locally delete a hash entry.
-
-=head2 New support for Abstract namespace sockets
-
-Abstract namespace sockets are Linux-specific socket type that live in
-AF_UNIX family, slightly abusing it to be able to use arbitrary
-character arrays as addresses: They start with nul byte and are not
-terminated by nul byte, but with the length passed to the socket()
-system call.
-
-=head2 32-bit limit on substr arguments removed
-
-The 32-bit limit on C<substr> arguments has now been removed. The full
-range of the system's signed and unsigned integers is now available for
-the C<pos> and C<len> arguments.
-
-=head1 Potentially Incompatible Changes
-
-=head2 Deprecations warn by default
-
-Over the years, Perl's developers have deprecated a number of language
-features for a variety of reasons. Perl now defaults to issuing a
-warning if a deprecated language feature is used. Many of the deprecations
-Perl now warns you about have been deprecated for many years. You can
-find a list of what was deprecated in a given release of Perl in the
-C<perl5xxdelta.pod> file for that release.
-
-To disable this feature in a given lexical scope, you should use C<no
-warnings 'deprecated';> For information about which language features
-are deprecated and explanations of various deprecation warnings, please
-see L<perldiag>. See L</Deprecations> below for the list of features
-and modules Perl's developers have deprecated as part of this release.
-
-=head2 Version number formats
-
-Acceptable version number formats have been formalized into "strict" and
-"lax" rules. C<package NAME VERSION> takes a strict version number.
-C<UNIVERSAL::VERSION> and the L<version> object constructors take lax
-version numbers. Providing an invalid version will result in a fatal
-error. The version argument in C<use NAME VERSION> is first parsed as a
-numeric literal or v-string and then passed to C<UNIVERSAL::VERSION>
-(and must then pass the "lax" format test).
-
-These formats are documented fully in the L<version> module. To a first
-approximation, a "strict" version number is a positive decimal number
-(integer or decimal-fraction) without exponentiation or else a
-dotted-decimal v-string with a leading 'v' character and at least three
-components. A "lax" version number allows v-strings with fewer than
-three components or without a leading 'v'. Under "lax" rules, both
-decimal and dotted-decimal versions may have a trailing "alpha"
-component separated by an underscore character after a fractional or
-dotted-decimal component.
-
-The L<version> module adds C<version::is_strict> and C<version::is_lax>
-functions to check a scalar against these rules.
-
-=head2 @INC reorganization
-
-In C<@INC>, C<ARCHLIB> and C<PRIVLIB> now occur after after the current
-version's C<site_perl> and C<vendor_perl>. Modules installed into
-C<site_perl> and C<vendor_perl> will now be loaded in preference to
-those installed in C<ARCHLIB> and C<PRIVLIB>.
-
-
-=head2 REGEXPs are now first class
-
-Internally, Perl now treats compiled regular expressions (such as
-those created with C<qr//>) as first class entities. Perl modules which
-serialize, deserialize or otherwise have deep interaction with Perl's
-internal data structures need to be updated for this change. Most
-affected CPAN modules have already been updated as of this writing.
-
-=head2 Switch statement changes
-
-The C<given>/C<when> switch statement handles complex statements better
-than Perl 5.10.0 did (These enhancements are also available in
-5.10.1 and subsequent 5.10 releases.) There are two new cases where
-C<when> now interprets its argument as a boolean, instead of an
-expression to be used in a smart match:
-
-=over
-
-=item flip-flop operators
-
-The C<..> and C<...> flip-flop operators are now evaluated in boolean
-context, following their usual semantics; see L<perlop/"Range Operators">.
-
-Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
-whether a given value is an integer between 1 and 10; you should use
-C<when ([1..10])> instead (note the array reference).
-
-However, contrary to 5.10.0, evaluating the flip-flop operators in
-boolean context ensures it can now be useful in a C<when()>, notably
-for implementing bistable conditions, like in:
-
- when (/^=begin/ .. /^=end/) {
- # do something
- }
-
-=item defined-or operator
-
-A compound expression involving the defined-or operator, as in
-C<when (expr1 // expr2)>, will be treated as boolean if the first
-expression is boolean. (This just extends the existing rule that applies
-to the regular or operator, as in C<when (expr1 || expr2)>.)
-
-=back
-
-=head2 Smart match changes
-
-Since Perl 5.10.0, Perl's developers have made a number of changes to
-the smart match operator. These, of course, also alter the behaviour
-of the switch statements where smart matching is implicitly used.
-These changes were also made for the 5.10.1 release, and will remain in
-subsequent 5.10 releases.
-
-=head3 Changes to type-based dispatch
-
-The smart match operator C<~~> is no longer commutative. The behaviour of
-a smart match now depends primarily on the type of its right hand
-argument. Moreover, its semantics have been adjusted for greater
-consistency or usefulness in several cases. While the general backwards
-compatibility is maintained, several changes must be noted:
-
-=over 4
-
-=item *
-
-Code references with an empty prototype are no longer treated specially.
-They are passed an argument like the other code references (even if they
-choose to ignore it).
-
-=item *
-
-C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
-returns a true value for each key of the hash (or element of the
-array), instead of passing the whole hash or array as a reference to
-the subroutine.
-
-=item *
-
-Due to the commutativity breakage, code references are no longer
-treated specially when appearing on the left of the C<~~> operator,
-but like any vulgar scalar.
-
-=item *
-
-C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
-hash). No implicit conversion to C<""> is done (as was the case in perl
-5.10.0).
-
-=item *
-
-C<$scalar ~~ @array> now always distributes the smart match across the
-elements of the array. It's true if one element in @array verifies
-C<$scalar ~~ $element>. This is a generalization of the old behaviour
-that tested whether the array contained the scalar.
-
-=back
-
-The full dispatch table for the smart match operator is given in
-L<perlsyn/"Smart matching in detail">.
-
-=head3 Smart match and overloading
-
-According to the rule of dispatch based on the rightmost argument type,
-when an object overloading C<~~> appears on the right side of the
-operator, the overload routine will always be called (with a 3rd argument
-set to a true value, see L<overload>.) However, when the object will
-appear on the left, the overload routine will be called only when the
-rightmost argument is a simple scalar. This way, distributivity of smart
-match across arrays is not broken, as well as the other behaviours with
-complex types (coderefs, hashes, regexes). Thus, writers of overloading
-routines for smart match mostly need to worry only with comparing
-against a scalar, and possibly with stringification overloading; the
-other common cases will be automatically handled consistently.
-
-C<~~> will now refuse to work on objects that do not overload it (in order
-to avoid relying on the object's underlying structure). (However, if the
-object overloads the stringification or the numification operators, and
-if overload fallback is active, it will be used instead, as usual.)
-
-=head2 Other potentially incompatible changes
-
-=over 4
-
-=item *
-
-The definitions of a number of Unicode properties have changed to match
-those of the current Unicode standard. These are listed above under
-L</Unicode overhaul>. This change may break code that expects the old
-definitions.
-
-=item *
-
-The boolkeys op has moved to the group of hash ops. This breaks binary
-compatibility.
-
-=item *
-
-Filehandles are now always blessed into C<IO::File>.
-
-The previous behaviour was to bless Filehandles into L<FileHandle>
-(an empty proxy class) if it was loaded into memory and otherwise
-to bless them into C<IO::Handle>.
-
-=item *
-
-The semantics of C<use feature :5.10*> have changed slightly.
-See L<"Modules and Pragmata"> for more information.
-
-=item *
-
-Perl's developers now use git, rather than Perforce. This should be
-a purely internal change only relevant to people actively working on
-the core. However, you may see minor difference in perl as a consequence
-of the change. For example in some of details of the output of C<perl
--V>. See L<perlrepository> for more information.
-
-=item *
-
-As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
-C<Test::Harness::Straps> module has been removed.
-See L</"Modules and Pragmata"> for more details.
-
-=item *
-
-As part of the C<ExtUtils::MakeMaker> upgrade, the
-C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
-have been removed from this distribution.
-
-=item *
-
-C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
-
-=item *
-
-C<length undef> now returns undef.
-
-=item *
-
-Unsupported private C API functions are now declared "static" to prevent
-leakage to Perl's public API.
-
-=item *
-
-To support the bootstrapping process, F<miniperl> no longer builds with
-UTF-8 support in the regexp engine.
-
-This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
-Without this there's a bootstrapping problem, as miniperl can't load
-the UTF-8 components of the regexp engine, because they're not yet built.
-
-=item *
-
-F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
-C<$ENV{PERL5LIB}>, and "C<.>"
-
-=item *
-
-A space or a newline is now required after a C<"#line XXX"> directive.
-
-=item *
-
-Tied filehandles now have an additional method EOF which provides the
-EOF type.
-
-=item *
-
-To better match all other flow control statements, C<foreach> may no
-longer be used as an attribute.
-
-=item *
-
-Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
-now been removed. The CPAN module C<< Filter::cpp >> can be used as an
-alternative.
-
-=back
-
-
-=head1 Deprecations
-
-From time to time, Perl's developers find it necessary to deprecate
-features or modules we've previously shipped as part of the core
-distribution. We are well aware of the pain and frustration that a
-backwards-incompatible change to Perl can cause for developers building
-or maintaining software in Perl. You can be sure that when we deprecate
-a functionality or syntax, it isn't a choice we make lightly. Sometimes,
-we choose to deprecate functionality or syntax because it was found to
-be poorly designed or implemented. Sometimes, this is because they're
-holding back other features or causing performance problems. Sometimes,
-the reasons are more complex. Wherever possible, we try to keep deprecated
-functionality available to developers in its previous form for at least
-one major release. So long as a deprecated feature isn't actively
-disrupting our ability to maintain and extend Perl, we'll try to leave
-it in place as long as possible.
-
-The following items are now deprecated:
-
-=over
-
-=item suidperl
-
-C<suidperl> is no longer part of Perl. It used to provide a mechanism to
-emulate setuid permission bits on systems that don't support it properly.
-
-=item Use of C<:=> to mean an empty attribute list
-
-An accident of Perl's parser meant that these constructions were all
-equivalent:
-
- my $pi := 4;
- my $pi : = 4;
- my $pi : = 4;
-
-with the C<:> being treated as the start of an attribute list, which
-ends before the C<=>. As whitespace is not significant here, all are
-parsed as an empty attribute list, hence all the above are equivalent
-to, and better written as
-
- my $pi = 4;
-
-because no attribute processing is done for an empty list.
-
-As is, this meant that C<:=> cannot be used as a new token, without
-silently changing the meaning of existing code. Hence that particular
-form is now deprecated, and will become a syntax error. If it is
-absolutely necessary to have empty attribute lists (for example,
-because of a code generator) then avoid the warning by adding a space
-before the C<=>.
-
-=item C<< UNIVERSAL->import() >>
-
-The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
-pass import arguments to a C<use UNIVERSAL> statement will result in a
-deprecation warning.
-
-=item Use of "goto" to jump into a construct
-
-Using C<goto> to jump from an outer scope into an inner scope is now
-deprecated. This rare use case was causing problems in the
-implementation of scopes.
-
-=item Custom character names in \N{name} that don't look like names
-
-In C<\N{I<name>}>, I<name> can be just about anything. The standard
-Unicode names have a very limited domain, but a custom name translator
-could create names that are, for example, made up entirely of punctuation
-symbols. It is now deprecated to make names that don't begin with an
-alphabetic character, and aren't alphanumeric or contain other than
-a very few other characters, namely spaces, dashes, parentheses
-and colons. Because of the added meaning of C<\N> (See L</C<\N>
-experimental regex escape>), names that look like curly brace -enclosed
-quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
-4 non-newlines; before a custom name C<3,4> could have been created.
-
-=item 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 warnings will issue a deprecation warning.
-
-If you ship a packaged version of Perl, either alone or as part of a
-larger system, then you should carefully consider the repercussions of
-core module deprecations. You may want to consider shipping your default
-build of Perl with packages for some or all deprecated modules which
-install into C<vendor> or C<site> perl library directories. This will
-inhibit the deprecation warnings.
-
-Alternatively, you may want to consider patching F<lib/deprecate.pm>
-to provide deprecation warnings specific to your packaging system
-or distribution of Perl, consistent with how your packaging system
-or distribution manages a staged transition from a release where the
-installation of a single package provides the given functionality, to
-a later release where the system administrator needs to know to install
-multiple packages to get that same functionality.
-
-You can silence these deprecation warnings by installing the modules
-in question from CPAN. To install the latest version of all of them,
-just install C<Task::Deprecations::5_12>.
-
-=over
-
-=item L<Class::ISA>
-
-=item L<Pod::Plainer>
-
-=item L<Shell>
-
-=item L<Switch>
-
-Switch is buggy and should be avoided. You may find Perl's new
-C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
-statements"> for more information.
-
-=back
-
-=item Assignment to $[
-
-=item Use of the attribute :locked on subroutines
-
-=item Use of "locked" with the attributes pragma
-
-=item Use of "unique" with the attributes pragma
-
-=item Perl_pmflag
-
-C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
-generates a deprecation warning, and it will be removed in a future
-release. Although listed as part of the API, it was never documented,
-and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
-core, it has been replaced by a static function.
-
-=item Numerous Perl 4-era libraries
-
-F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
-F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
-F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
-F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
-F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
-F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
-F<timelocal.pl> are all now deprecated. Earlier, Perl's developers
-intended to remove these libraries from Perl's core for the 5.14.0 release.
-
-During final testing before the release of 5.12.0, several developers
-discovered current production code using these ancient libraries, some
-inside the Perl core itself. Accordingly, the pumpking granted them
-a stay of execution. They will begin to warn about their deprecation
-in the 5.14.0 release and will be removed in the 5.16.0 release.
-
-
-=back
-
-=head1 Unicode overhaul
-
-Perl's developers have made a concerted effort to update Perl to be in
-sync with the latest Unicode standard. Changes for this include:
-
-Perl can now handle every Unicode character property. New documentation,
-L<perluniprops>, lists all available non-Unihan character properties. By
-default, perl does not expose Unihan, deprecated or Unicode-internal
-properties. See below for more details on these; there is also a section
-in the pod listing them, and explaining why they are not exposed.
-
-Perl now fully supports the Unicode compound-style of using C<=>
-and C<:> in writing regular expressions: C<\p{property=value}> and
-C<\p{property:value}> (both of which mean the same thing).
-
-Perl now fully supports the Unicode loose matching rules for text between
-the braces in C<\p{...}> constructs. In addition, Perl allows underscores
-between digits of numbers.
-
-Perl now accepts all the Unicode-defined synonyms for properties and
-property values.
-
-C<qr/\X/>, which matches a Unicode logical character, has
-been expanded to work better with various Asian languages. It
-now is defined as an I<extended grapheme cluster>. (See
-L<http://www.unicode.org/reports/tr29/>). Anything matched previously
-and that made sense will continue to be accepted. Additionally:
-
-=over
-
-=item *
-
-C<\X> will not break apart a C<S<CR LF>> sequence.
-
-=item *
-
-C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
-characters.
-
-=item *
-
-C<\X> will now always match at least one character, including an initial
-mark. Marks generally come after a base character, but it is possible in
-Unicode to have them in isolation, and C<\X> will now handle that case,
-for example at the beginning of a line, or after a C<ZWSP>. And this is
-the part where C<\X> doesn't match the things that it used to that don't
-make sense. Formerly, for example, you could have the nonsensical case
-of an accented LF.
-
-=item *
-
-C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
-and Lao exception cases.
-
-=back
-
-Otherwise, this change should be transparent for the non-affected
-languages.
-
-C<\p{...}> matches using the Canonical_Combining_Class property were
-completely broken in previous releases of Perl. They should now work
-correctly.
-
-Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
-and a Perl extension had the same name, which led to neither matching
-all the correct values (with more than 100 mistakes in one, and several
-thousand in the other). The Perl extension has now been renamed to be
-C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
-same meaning as was previously intended, namely the union of all the
-non-canonical Decomposition types, with Unicode C<Compat> being just
-one of those.
-
-C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
-
-C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
-says they should. This means they each match a few more characters than
-they used to.
-
-C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
-means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
-nor Format (gc=cf) code points. The Format code points represent the
-biggest possible problem. All but 36 of them are either officially
-deprecated or strongly discouraged from being used. Of those 36, likely
-the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
-WJ, and similar characters, plus bidirectional controls.
-
-C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
-5.12, Perl's definition definition included a number of things that aren't
-really alpha (all marks) while omitting many that were. The definitions
-of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
-changed accordingly.
-
-C<\p{Word}> no longer incorrectly matches non-word characters such
-as fractions.
-
-C<\p{Print}> no longer matches the line control characters: Tab, LF,
-CR, FF, VT, and NEL. This brings it in line with standards and the
-documentation.
-
-C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
-means that in addition to the characters it currently matches,
-C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
-example U+FF10: FULLWIDTH DIGIT ZERO.
-
-The Numeric type property has been extended to include the Unihan
-characters.
-
-There is a new Perl extension, the 'Present_In', or simply 'In',
-property. This is an extension of the Unicode Age property, but
-C<\p{In=5.0}> matches any code point whose usage has been determined
-I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
-added in I<precisely> version 5.0.
-
-A number of properties now have the correct values for unassigned
-code points. The affected properties are Bidi_Class, East_Asian_Width,
-Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
-and Line_Break.
-
-The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
-are now up to date with current Unicode definitions.
-
-Earlier versions of Perl erroneously exposed certain properties that
-are supposed to be Unicode internal-only. Use of these in regular
-expressions will now generate, if enabled, a deprecation warning message.
-The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
-Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
-Other_Math, and Other_Uppercase.
-
-It is now possible to change which Unicode properties Perl understands
-on a per-installation basis. As mentioned above, certain properties
-are turned off by default. These include all the Unihan properties
-(which should be accessible via the CPAN module Unicode::Unihan) and any
-deprecated or Unicode internal-only property that Perl has never exposed.
-
-The generated files in the C<lib/unicore/To> directory are now more
-clearly marked as being stable, directly usable by applications. New hash
-entries in them give the format of the normal entries, which allows for
-easier machine parsing. Perl can generate files in this directory for
-any property, though most are suppressed. You can find instructions
-for changing which are written in L<perluniprops>.
-
-=head1 Modules and Pragmata
-
-=head2 New Modules and Pragmata
-
-=over 4
-
-=item C<autodie>
-
-C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
-The bundled version is 2.06_01. Note that in this release, using a string
-eval when C<autodie> is in effect can cause the autodie behaviour to leak
-into the surrounding scope. See L<autodie/"BUGS"> for more details.
-
-Version 2.06_01 has been added to the Perl core.
-
-=item C<Compress::Raw::Bzip2>
-
-Version 2.024 has been added to the Perl core.
-
-=item C<overloading>
-
-C<overloading> allows you to lexically disable or enable overloading
-for some or all operations.
-
-Version 0.001 has been added to the Perl core.
-
-=item C<parent>
-
-C<parent> establishes an ISA relationship with base classes at compile
-time. It provides the key feature of C<base> without further unwanted
-behaviors.
-
-Version 0.223 has been added to the Perl core.
-
-=item C<Parse::CPAN::Meta>
-
-Version 1.40 has been added to the Perl core.
-
-=item C<VMS::DCLsym>
-
-Version 1.03 has been added to the Perl core.
-
-=item C<VMS::Stdio>
-
-Version 2.4 has been added to the Perl core.
-
-=item C<XS::APItest::KeywordRPN>
-
-Version 0.003 has been added to the Perl core.
-
-=back
-
-=head2 Updated Pragmata
-
-=over 4
-
-=item C<base>
-
-Upgraded from version 2.13 to 2.15.
-
-=item C<bignum>
-
-Upgraded from version 0.22 to 0.23.
-
-=item C<charnames>
-
-C<charnames> now contains the Unicode F<NameAliases.txt> database file.
-This has the effect of adding some extra C<\N> character names that
-formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
-LETTER GHA}">.
-
-Upgraded from version 1.06 to 1.07.
-
-=item C<constant>
-
-Upgraded from version 1.13 to 1.20.
-
-=item C<diagnostics>
-
-C<diagnostics> now supports %.0f formatting internally.
-
-C<diagnostics> no longer suppresses C<Use of uninitialized value in range
-(or flip)> warnings. [perl #71204]
-
-Upgraded from version 1.17 to 1.19.
-
-=item C<feature>
-
-In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
-bundles has changed slightly. The last component, if any (i.e. C<X>) is
-simply ignored. This is predicated on the assumption that new features
-will not, in general, be added to maintenance releases. So C<:5.10>
-and C<:5.10.X> have identical effect. This is a change to the behaviour
-documented for 5.10.0.
-
-C<feature> now includes the C<unicode_strings> feature:
-
- use feature "unicode_strings";
-
-This pragma turns on Unicode semantics for the case-changing operations
-(C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
-internal UTF-8 flag set, but that contain single-byte characters between
-128 and 255.
-
-Upgraded from version 1.11 to 1.16.
-
-=item C<less>
-
-C<less> now includes the C<stash_name> method to allow subclasses of
-C<less> to pick where in %^H to store their stash.
-
-Upgraded from version 0.02 to 0.03.
-
-=item C<lib>
-
-Upgraded from version 0.5565 to 0.62.
-
-=item C<mro>
-
-C<mro> is now implemented as an XS extension. The documented interface has
-not changed. Code relying on the implementation detail that some C<mro::>
-methods happened to be available at all times gets to "keep both pieces".
-
-Upgraded from version 1.00 to 1.02.
-
-=item C<overload>
-
-C<overload> now allow overloading of 'qr'.
-
-Upgraded from version 1.06 to 1.10.
-
-=item C<threads>
-
-Upgraded from version 1.67 to 1.75.
-
-=item C<threads::shared>
-
-Upgraded from version 1.14 to 1.32.
-
-=item C<version>
-
-C<version> now has support for L</Version number formats> as described
-earlier in this document and in its own documentation.
-
-Upgraded from version 0.74 to 0.82.
-
-=item C<warnings>
-
-C<warnings> has a new C<warnings::fatal_enabled()> function. It also
-includes a new C<illegalproto> warning category. See also L</New or
-Changed Diagnostics> for this change.
-
-Upgraded from version 1.06 to 1.09.
-
-=back
-
-=head2 Updated Modules
-
-=over 4
-
-=item C<Archive::Extract>
-
-Upgraded from version 0.24 to 0.38.
-
-=item C<Archive::Tar>
-
-Upgraded from version 1.38 to 1.54.
-
-=item C<Attribute::Handlers>
-
-Upgraded from version 0.79 to 0.87.
-
-=item C<AutoLoader>
-
-Upgraded from version 5.63 to 5.70.
-
-=item C<B::Concise>
-
-Upgraded from version 0.74 to 0.78.
-
-=item C<B::Debug>
-
-Upgraded from version 1.05 to 1.12.
-
-=item C<B::Deparse>
-
-Upgraded from version 0.83 to 0.96.
-
-=item C<B::Lint>
-
-Upgraded from version 1.09 to 1.11_01.
-
-=item C<CGI>
-
-Upgraded from version 3.29 to 3.48.
-
-=item C<Class::ISA>
-
-Upgraded from version 0.33 to 0.36.
-
-NOTE: C<Class::ISA> is deprecated and may be removed from a future
-version of Perl.
-
-=item C<Compress::Raw::Zlib>
-
-Upgraded from version 2.008 to 2.024.
-
-=item C<CPAN>
-
-Upgraded from version 1.9205 to 1.94_56.
-
-=item C<CPANPLUS>
-
-Upgraded from version 0.84 to 0.90.
-
-=item C<CPANPLUS::Dist::Build>
-
-Upgraded from version 0.06_02 to 0.46.
-
-=item C<Data::Dumper>
-
-Upgraded from version 2.121_14 to 2.125.
-
-=item C<DB_File>
-
-Upgraded from version 1.816_1 to 1.820.
-
-=item C<Devel::PPPort>
-
-Upgraded from version 3.13 to 3.19.
-
-=item C<Digest>
-
-Upgraded from version 1.15 to 1.16.
-
-=item C<Digest::MD5>
-
-Upgraded from version 2.36_01 to 2.39.
-
-=item C<Digest::SHA>
-
-Upgraded from version 5.45 to 5.47.
-
-=item C<Encode>
-
-Upgraded from version 2.23 to 2.39.
-
-=item C<Exporter>
-
-Upgraded from version 5.62 to 5.64_01.
-
-=item C<ExtUtils::CBuilder>
-
-Upgraded from version 0.21 to 0.27.
-
-=item C<ExtUtils::Command>
-
-Upgraded from version 1.13 to 1.16.
-
-=item C<ExtUtils::Constant>
-
-Upgraded from version 0.2 to 0.22.
-
-=item C<ExtUtils::Install>
-
-Upgraded from version 1.44 to 1.55.
-
-=item C<ExtUtils::MakeMaker>
-
-Upgraded from version 6.42 to 6.56.
-
-=item C<ExtUtils::Manifest>
-
-Upgraded from version 1.51_01 to 1.57.
-
-=item C<ExtUtils::ParseXS>
-
-Upgraded from version 2.18_02 to 2.21.
-
-=item C<File::Fetch>
-
-Upgraded from version 0.14 to 0.24.
-
-=item C<File::Path>
-
-Upgraded from version 2.04 to 2.08_01.
-
-=item C<File::Temp>
-
-Upgraded from version 0.18 to 0.22.
-
-=item C<Filter::Simple>
-
-Upgraded from version 0.82 to 0.84.
-
-=item C<Filter::Util::Call>
-
-Upgraded from version 1.07 to 1.08.
-
-=item C<Getopt::Long>
-
-Upgraded from version 2.37 to 2.38.
-
-=item C<IO>
-
-Upgraded from version 1.23_01 to 1.25_02.
-
-=item C<IO::Zlib>
-
-Upgraded from version 1.07 to 1.10.
-
-=item C<IPC::Cmd>
-
-Upgraded from version 0.40_1 to 0.54.
-
-=item C<IPC::SysV>
-
-Upgraded from version 1.05 to 2.01.
-
-=item C<Locale::Maketext>
-
-Upgraded from version 1.12 to 1.14.
-
-=item C<Locale::Maketext::Simple>
-
-Upgraded from version 0.18 to 0.21.
-
-=item C<Log::Message>
-
-Upgraded from version 0.01 to 0.02.
-
-=item C<Log::Message::Simple>
-
-Upgraded from version 0.04 to 0.06.
-
-=item C<Math::BigInt>
-
-Upgraded from version 1.88 to 1.89_01.
-
-=item C<Math::BigInt::FastCalc>
-
-Upgraded from version 0.16 to 0.19.
-
-=item C<Math::BigRat>
-
-Upgraded from version 0.21 to 0.24.
-
-=item C<Math::Complex>
-
-Upgraded from version 1.37 to 1.56.
-
-=item C<Memoize>
-
-Upgraded from version 1.01_02 to 1.01_03.
-
-=item C<MIME::Base64>
-
-Upgraded from version 3.07_01 to 3.08.
-
-=item C<Module::Build>
-
-Upgraded from version 0.2808_01 to 0.3603.
-
-=item C<Module::CoreList>
-
-Upgraded from version 2.12 to 2.29.
-
-=item C<Module::Load>
-
-Upgraded from version 0.12 to 0.16.
-
-=item C<Module::Load::Conditional>
-
-Upgraded from version 0.22 to 0.34.
-
-=item C<Module::Loaded>
-
-Upgraded from version 0.01 to 0.06.
-
-=item C<Module::Pluggable>
-
-Upgraded from version 3.6 to 3.9.
-
-=item C<Net::Ping>
-
-Upgraded from version 2.33 to 2.36.
-
-=item C<NEXT>
-
-Upgraded from version 0.60_01 to 0.64.
-
-=item C<Object::Accessor>
-
-Upgraded from version 0.32 to 0.36.
-
-=item C<Package::Constants>
-
-Upgraded from version 0.01 to 0.02.
-
-=item C<PerlIO>
-
-Upgraded from version 1.04 to 1.06.
-
-=item C<Pod::Parser>
-
-Upgraded from version 1.35 to 1.37.
-
-=item C<Pod::Perldoc>
-
-Upgraded from version 3.14_02 to 3.15_02.
-
-=item C<Pod::Plainer>
-
-Upgraded from version 0.01 to 1.02.
-
-NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
-version of Perl.
-
-=item C<Pod::Simple>
-
-Upgraded from version 3.05 to 3.13.
-
-=item C<Safe>
-
-Upgraded from version 2.12 to 2.22.
-
-=item C<SelfLoader>
-
-Upgraded from version 1.11 to 1.17.
-
-=item C<Storable>
-
-Upgraded from version 2.18 to 2.22.
-
-=item C<Switch>
-
-Upgraded from version 2.13 to 2.16.
-
-NOTE: C<Switch> is deprecated and may be removed from a future version
-of Perl.
-
-=item C<Sys::Syslog>
-
-Upgraded from version 0.22 to 0.27.
-
-=item C<Term::ANSIColor>
-
-Upgraded from version 1.12 to 2.02.
-
-=item C<Term::UI>
-
-Upgraded from version 0.18 to 0.20.
-
-=item C<Test>
-
-Upgraded from version 1.25 to 1.25_02.
-
-=item C<Test::Harness>
-
-Upgraded from version 2.64 to 3.17.
-
-=item C<Test::Simple>
-
-Upgraded from version 0.72 to 0.94.
-
-=item C<Text::Balanced>
-
-Upgraded from version 2.0.0 to 2.02.
-
-=item C<Text::ParseWords>
-
-Upgraded from version 3.26 to 3.27.
-
-=item C<Text::Soundex>
-
-Upgraded from version 3.03 to 3.03_01.
-
-=item C<Thread::Queue>
-
-Upgraded from version 2.00 to 2.11.
-
-=item C<Thread::Semaphore>
-
-Upgraded from version 2.01 to 2.09.
-
-=item C<Tie::RefHash>
-
-Upgraded from version 1.37 to 1.38.
-
-=item C<Time::HiRes>
-
-Upgraded from version 1.9711 to 1.9719.
-
-=item C<Time::Local>
-
-Upgraded from version 1.18 to 1.1901_01.
-
-=item C<Time::Piece>
-
-Upgraded from version 1.12 to 1.15.
-
-=item C<Unicode::Collate>
-
-Upgraded from version 0.52 to 0.52_01.
-
-=item C<Unicode::Normalize>
-
-Upgraded from version 1.02 to 1.03.
-
-=item C<Win32>
-
-Upgraded from version 0.34 to 0.39.
-
-=item C<Win32API::File>
-
-Upgraded from version 0.1001_01 to 0.1101.
-
-=item C<XSLoader>
-
-Upgraded from version 0.08 to 0.10.
-
-=back
-
-=head2 Removed Modules and Pragmata
-
-=over 4
-
-=item C<attrs>
-
-Removed from the Perl core. Prior version was 1.02.
-
-=item C<CPAN::API::HOWTO>
-
-Removed from the Perl core. Prior version was 'undef'.
-
-=item C<CPAN::DeferedCode>
-
-Removed from the Perl core. Prior version was 5.50.
-
-=item C<CPANPLUS::inc>
-
-Removed from the Perl core. Prior version was 'undef'.
-
-=item C<DCLsym>
-
-Removed from the Perl core. Prior version was 1.03.
-
-=item C<ExtUtils::MakeMaker::bytes>
-
-Removed from the Perl core. Prior version was 6.42.
-
-=item C<ExtUtils::MakeMaker::vmsish>
-
-Removed from the Perl core. Prior version was 6.42.
-
-=item C<Stdio>
-
-Removed from the Perl core. Prior version was 2.3.
-
-=item C<Test::Harness::Assert>
-
-Removed from the Perl core. Prior version was 0.02.
-
-=item C<Test::Harness::Iterator>
-
-Removed from the Perl core. Prior version was 0.02.
-
-=item C<Test::Harness::Point>
-
-Removed from the Perl core. Prior version was 0.01.
-
-=item C<Test::Harness::Results>
-
-Removed from the Perl core. Prior version was 0.01.
-
-=item C<Test::Harness::Straps>
-
-Removed from the Perl core. Prior version was 0.26_01.
-
-=item C<Test::Harness::Util>
-
-Removed from the Perl core. Prior version was 0.01.
-
-=item C<XSSymSet>
-
-Removed from the Perl core. Prior version was 1.1.
-
-=back
-
-=head2 Deprecated Modules and Pragmata
-
-See L</Deprecated Modules> above.
-
-
-=head1 Documentation
-
-=head2 New Documentation
-
-=over 4
-
-=item *
-
-L<perlhaiku> contains instructions on how to build perl for the Haiku
-platform.
-
-=item *
-
-L<perlmroapi> describes the new interface for pluggable Method Resolution
-Orders.
-
-=item *
-
-L<perlperf>, by Richard Foley, provides an introduction to the use of
-performance and optimization techniques which can be used with particular
-reference to perl programs.
-
-=item *
-
-L<perlrepository> describes how to access the perl source using the I<git>
-version control system.
-
-=item *
-
-L<perlpolicy> extends the "Social contract about contributed modules" into
-the beginnings of a document on Perl porting policies.
-
-=back
-
-=head2 Changes to Existing Documentation
-
-
-=over
-
-=item *
-
-The various large F<Changes*> files (which listed every change made
-to perl over the last 18 years) have been removed, and replaced by a
-small file, also called F<Changes>, which just explains how that same
-information may be extracted from the git version control system.
-
-=item *
-
-F<Porting/patching.pod> has been deleted, as it mainly described
-interacting with the old Perforce-based repository, which is now obsolete.
-Information still relevant has been moved to L<perlrepository>.
-
-=item *
-
-The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
-as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
-BLOCK>, although actually using the latter may not be the best idea for
-the readability of your source code.
-
-=item *
-
-Documented -X overloading.
-
-=item *
-
-Documented that C<when()> treats specially most of the filetest operators
-
-=item *
-
-Documented C<when> as a syntax modifier.
-
-=item *
-
-Eliminated "Old Perl threads tutorial", which described 5005 threads.
-
-F<pod/perlthrtut.pod> is the same material reworked for ithreads.
-
-=item *
-
-Correct previous documentation: v-strings are not deprecated
-
-With version objects, we need them to use MODULE VERSION syntax. This
-patch removes the deprecation notice.
-
-=item *
-
-Security contact information is now part of L<perlsec>.
-
-=item *
-
-A significant fraction of the core documentation has been updated to
-clarify the behavior of Perl's Unicode handling.
-
-Much of the remaining core documentation has been reviewed and edited
-for clarity, consistent use of language, and to fix the spelling of Tom
-Christiansen's name.
-
-=item *
-
-The Pod specification (L<perlpodspec>) has been updated to bring the
-specification in line with modern usage already supported by most Pod
-systems. A parameter string may now follow the format name in a
-"begin/end" region. Links to URIs with a text description are now
-allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
-deprecated.
-
-=item *
-
-L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
-conditional loading of modules despite the implicit BEGIN block around
-C<use>.
-
-=item *
-
-The documentation for C<$1> in perlvar.pod has been clarified.
-
-=item *
-
-C<\N{U+I<code point>}> is now documented.
-
-=back
-
-=head1 Selected Performance Enhancements
-
-=over 4
-
-=item *
-
-A new internal cache means that C<isa()> will often be faster.
-
-=item *
-
-The implementation of C<C3> Method Resolution Order has been
-optimised - linearisation for classes with single inheritance is 40%
-faster. Performance for multiple inheritance is unchanged.
-
-=item *
-
-Under C<use locale>, the locale-relevant information is now cached on
-read-only values, such as the list returned by C<keys %hash>. This makes
-operations such as C<sort keys %hash> in the scope of C<use locale>
-much faster.
-
-=item *
-
-Empty C<DESTROY> methods are no longer called.
-
-=item *
-
-C<Perl_sv_utf8_upgrade()> is now faster.
-
-=item *
-
-C<keys> on empty hash is now faster.
-
-=item *
-
-C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
-
-=item *
-
-The string repetition operator (C<$str x $num>) is now several times
-faster when C<$str> has length one or C<$num> is large.
-
-=item *
-
-Reversing an array to itself (as in C<@a = reverse @a>) in void context
-now happens in-place and is several orders of magnitude faster than
-it used to be. It will also preserve non-existent elements whenever
-possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
-and C<DELETE> methods.
-
-=back
-
-=head1 Installation and Configuration Improvements
-
-=over 4
-
-=item *
-
-L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
-generated at build time, rather than being shipped as part of the release.
-
-=item *
-
-If C<vendorlib> and C<vendorarch> are the same, then they are only added
-to C<@INC> once.
-
-=item *
-
-C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
-perl is built with C<-Dusedevel>.
-
-=item *
-
-F<Configure> will enable use of C<-fstack-protector>, to provide protection
-against stack-smashing attacks, if the compiler supports it.
-
-=item *
-
-F<Configure> will now determine the correct prototypes for re-entrant
-functions and for C<gconvert> if you are using a C++ compiler rather
-than a C compiler.
-
-=item *
-
-On Unix, if you build from a tree containing a git repository, the
-configuration process will note the commit hash you have checked out, for
-display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
-are automatically added to the list of local patches displayed by
-C<perl -V>.
-
-=item *
-
-Perl now supports SystemTap's C<dtrace> compatibility layer and an
-issue with linking C<miniperl> has been fixed in the process.
-
-=item *
-
-perldoc now uses C<less -R> instead of C<less> for improved behaviour
-in the face of C<groff>'s new usage of ANSI escape codes.
-
-=item *
-
-
-C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
-C<USE_ATTRIBUTES_FOR_PERLIO>.
-
-=item *
-
-As part of the flattening of F<ext>, all extensions on all platforms are
-built by F<make_ext.pl>. This replaces the Unix-specific
-F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
-F<win32/buildext.pl>.
-
-=back
-
-=head1 Internal Changes
-
-Each release of Perl sees numerous internal changes which shouldn't
-affect day to day usage but may still be notable for developers working
-with Perl's source code.
-
-=over
-
-=item *
-
-The J.R.R. Tolkien quotes at the head of C source file have been checked
-and proper citations added, thanks to a patch from Tom Christiansen.
-
-=item *
-
-The internal structure of the dual-life modules traditionally found in
-the F<lib/> and F<ext/> directories in the perl source has changed
-significantly. Where possible, dual-lifed modules have been extracted
-from F<lib/> and F<ext/>.
-
-Dual-lifed modules maintained by Perl's developers as part of the Perl
-core now live in F<dist/>. Dual-lifed modules maintained primarily on
-CPAN now live in F<cpan/>. When reporting a bug in a module located
-under F<cpan/>, please send your bug report directly to the module's
-bug tracker or author, rather than Perl's bug tracker.
-
-=item *
-
-C<\N{...}> now compiles better, always forces UTF-8 internal representation
-
-Perl's developers have fixed several problems with the recognition of
-C<\N{...}> constructs. As part of this, perl will store any scalar
-or regex containing C<\N{I<name>}> or C<\N{U+I<code point>}> in its
-definition in UTF-8 format. (This was true previously for all occurrences
-of C<\N{I<name>}> that did not use a custom translator, but now it's
-always true.)
-
-=item *
-
-Perl_magic_setmglob now knows about globs, fixing RT #71254.
-
-=item *
-
-C<SVt_RV> no longer exists. RVs are now stored in IVs.
-
-=item *
-
-C<Perl_vcroak()> now accepts a null first argument. In addition, a full
-audit was made of the "not NULL" compiler annotations, and those for
-several other internal functions were corrected.
-
-=item *
-
-New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
-have been added to formalise the temporary saving of the C<errno>
-variable.
-
-=item *
-
-The function C<Perl_sv_insert_flags> has been added to augment
-C<Perl_sv_insert>.
-
-=item *
-
-The function C<Perl_newSV_type(type)> has been added, equivalent to
-C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
-
-=item *
-
-The function C<Perl_newSVpvn_flags()> has been added, equivalent to
-C<Perl_newSVpvn()> and then performing the action relevant to the flag.
-
-Two flag bits are currently supported.
-
-=over 4
-
-=item *
-
-C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
-not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
-C<newSVpvn_utf8()> is available for this.
-
-=item *
-
-C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
-
-=back
-
-There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
-
-=item *
-
-The function C<Perl_croak_xs_usage> has been added as a wrapper to
-C<Perl_croak>.
-
-=item *
-
-Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
-
-=item *
-
-C<PL_na> has been exterminated from the core code, replaced by local
-STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
-C<PL_na>, which is a pointer dereference into the interpreter structure
-under ithreads, and a global variable otherwise.
-
-=item *
-
-C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
-on the scalar. It now updates the linked list to remove each piece of
-magic as it is freed.
-
-=item *
-
-Under ithreads, the regex in C<PL_reg_curpm> is now reference
-counted. This eliminates a lot of hackish workarounds to cope with it
-not being reference counted.
-
-=item *
-
-C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
-This has been fixed.
-
-=item *
-
-The I<public> IV and NV flags are now not set if the string value has
-trailing "garbage". This behaviour is consistent with not setting the
-public IV or NV flags if the value is out of range for the type.
-
-=item *
-
-Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
-been replaced by C<NULL> in the core code, and non-dual-life modules,
-as C<NULL> is clearer to those unfamiliar with the core code.
-
-=item *
-
-A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
-not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
-C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
-casting away C<const>. This allows proper compile-time auditing of
-C<const> correctness in the core, and helped picked up some errors
-(now fixed).
-
-=item *
-
-Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
-stack and mortalizing them.
-
-=item *
-
-Use of the private structure C<mro_meta> has changed slightly. Nothing
-outside the core should be accessing this directly anyway.
-
-=item *
-
-A new tool, F<Porting/expand-macro.pl> has been added, that allows you
-to view how a C preprocessor macro would be expanded when compiled.
-This is handy when trying to decode the macro hell that is the perl
-guts.
-
-=back
-
-=head1 Testing
-
-=head2 Testing improvements
-
-=over 4
-
-=item Parallel tests
-
-The core distribution can now run its regression tests in parallel on
-Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
-your environment to the number of tests to run in parallel, and run
-C<make test_harness>. On a Bourne-like shell, this can be done as
-
- TEST_JOBS=3 make test_harness # Run 3 tests in parallel
-
-An environment variable is used, rather than parallel make itself, because
-L<TAP::Harness> needs to be able to schedule individual non-conflicting test
-scripts itself, and there is no standard interface to C<make> utilities to
-interact with their job schedulers.
-
-Note that currently some test scripts may fail when run in parallel (most
-notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
-again sequentially and see if the failures go away.
-
-=item Test harness flexibility
-
-It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
-
-=item Test watchdog
-
-Several tests that have the potential to hang forever if they fail now
-incorporate a "watchdog" functionality that will kill them after a timeout,
-which helps ensure that C<make test> and C<make test_harness> run to
-completion automatically.
-
-
-=back
-
-=head2 New Tests
-
-Perl's developers have added a number of new tests to the core.
-In addition to the items listed below, many modules updated from CPAN
-incorporate new tests.
-
-=over 4
-
-=item *
-
-Significant cleanups to core tests to ensure that language and
-interpreter features are not used before they're tested.
-
-=item *
-
-C<make test_porting> now runs a number of important pre-commit checks
-which might be of use to anyone working on the Perl core.
-
-=item *
-
-F<t/porting/podcheck.t> automatically checks the well-formedness of
-POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
-dual-lifed modules which are primarily maintained outside the Perl core.
-
-=item *
-
-F<t/porting/manifest.t> now tests that all files listed in MANIFEST
-are present.
-
-=item *
-
-F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
-
-=item *
-
-F<t/comp/retainedlines.t> checks that the debugger can retain source
-lines from C<eval>.
-
-=item *
-
-F<t/io/perlio_fail.t> checks that bad layers fail.
-
-=item *
-
-F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
-
-=item *
-
-F<t/io/perlio_open.t> checks that certain special forms of open work.
-
-=item *
-
-F<t/io/perlio.t> includes general PerlIO tests.
-
-=item *
-
-F<t/io/pvbm.t> checks that there is no unexpected interaction between
-the internal types C<PVBM> and C<PVGV>.
-
-=item *
-
-F<t/mro/package_aliases.t> checks that mro works properly in the presence
-of aliased packages.
-
-=item *
-
-F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
-
-=item *
-
-F<t/op/index_thr.t> tests the interaction of C<index> and threads.
-
-=item *
-
-F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
-
-=item *
-
-F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
-
-=item *
-
-F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
-
-=item *
-
-F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
-embedded C<qr//> and threads.
-
-=item *
-
-F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
-expressions.
-
-=item *
-
-F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
-properties and threads.
-
-=item *
-
-F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
-
-=item *
-
-F<t/op/reg_posixcc.t> checks that POSIX character classes behave
-consistently.
-
-=item *
-
-F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
-
-=item *
-
-F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
-
-=item *
-
-F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
-
-=item *
-
-F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
-
-=item *
-
-F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
-
-=item *
-
-F<t/uni/tie.t> checks that Unicode and C<tie> work.
-
-=item *
-
-F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
-
-=item *
-
-F<t/comp/form_scope.t> tests format scoping.
-
-=item *
-
-F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
-
-=item *
-
-F<t/op/filetest_t.t> tests if -t file test works.
-
-=item *
-
-F<t/op/qr.t> tests C<qr>.
-
-=item *
-
-F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
-
-=item *
-
-F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
-
-=item *
-
-F<t/op/filehandle.t> tests some suitably portable filetest operators
-to check that they work as expected, particularly in the light of some
-internal changes made in how filehandles are blessed.
-
-=item *
-
-F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
-can now be handed to C<gmtime> and C<localtime>, do not cause an internal
-overflow or an excessively long loop.
-
-=back
-
-
-=head1 New or Changed Diagnostics
-
-=head2 New Diagnostics
-
-=over
-
-=item *
-
-SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
-The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
-that was enabled when the F<perl> binary was compiled.
-
-=item *
-
-Smartmatch resolution tracing has been added as a new diagnostic. Use
-C<-DM> to enable it.
-
-=item *
-
-A new debugging flag C<-DB> now dumps subroutine definitions, leaving
-C<-Dx> for its original purpose of dumping syntax trees.
-
-=item *
-
-Perl 5.12 provides a number of new diagnostic messages to help you write
-better code. See L<perldiag> for details of these new messages.
-
-=over 4
-
-=item *
-
-C<Bad plugin affecting keyword '%s'>
-
-=item *
-
-C<gmtime(%.0f) too large>
-
-=item *
-
-C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
-
-=item *
-
-C<Lexing code internal error (%s)>
-
-=item *
-
-C<localtime(%.0f) too large>
-
-=item *
-
-C<Overloaded dereference did not return a reference>
-
-=item *
-
-C<Overloaded qr did not return a REGEXP>
-
-=item *
-
-C<Perl_pmflag() is deprecated, and will be removed from the XS API>
-
-=item *
-
-C<lvalue attribute ignored after the subroutine has been defined>
-
-This new warning is issued when one attempts to mark a subroutine as
-lvalue after it has been defined.
-
-=item *
-
-Perl now warns you if C<++> or C<--> are unable to change the value
-because it's beyond the limit of representation.
-
-This uses a new warnings category: "imprecision".
-
-=item *
-
-C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
-
-=item *
-
-C<Show constant in "Useless use of a constant in void context">
-
-=item *
-
-C<Prototype after '%s'>
-
-=item *
-
-C<panic: sv_chop %s>
-
-This new fatal error occurs when the C routine C<Perl_sv_chop()> was
-passed a position that is not within the scalar's string buffer. This
-could be caused by buggy XS code, and at this point recovery is not
-possible.
-
-=item *
-
-The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
-C<charnames> handler returns malformed UTF-8.
-
-=item *
-
-If an unresolved named character or sequence was encountered when
-compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
-by the lexer> is now produced. This can happen, for example, when using a
-single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
-for more examples of how the lexer can get bypassed.
-
-=item *
-
-C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
-triggered when the character constant represented by C<...> is not a
-valid hexadecimal number.
-
-=item *
-
-The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
-class, just like C<.> in a character class loses its special meaning,
-and will cause the fatal error C<\N in a character class must be a named
-character: \N{...}>.
-
-=item *
-
-The rules on what is legal for the C<...> in C<\N{...}> have been
-tightened up so that unless the C<...> begins with an alphabetic
-character and continues with a combination of alphanumerics, dashes,
-spaces, parentheses or colons then the warning C<Deprecated character(s)
-in \N{...} starting at '%s'> is now issued.
-
-=item *
-
-The warning C<Using just the first characters returned by \N{}> will
-be issued if the C<charnames> handler returns a sequence of characters
-which exceeds the limit of the number of characters that can be used. The
-message will indicate which characters were used and which were discarded.
-
-=back
-
-=back
-
-=head2 Changed Diagnostics
-
-A number of existing diagnostic messages have been improved or corrected:
-
-=over
-
-=item *
-
-A new warning category C<illegalproto> allows finer-grained control of
-warnings around function prototypes.
-
-The two warnings:
-
-=over
-
-=item C<Illegal character in prototype for %s : %s>
-
-=item C<Prototype after '%c' for %s : %s>
-
-=back
-
-have been moved from the C<syntax> top-level warnings category into a new
-first-level category, C<illegalproto>. These two warnings are currently
-the only ones emitted during parsing of an invalid/illegal prototype,
-so one can now use
-
- no warnings 'illegalproto';
-
-to suppress only those, but not other syntax-related warnings. Warnings
-where prototypes are changed, ignored, or not met are still in the
-C<prototype> category as before.
-
-=item *
-
-C<Deep recursion on subroutine "%s">
-
-It is now possible to change the depth threshold for this warning from the
-default of 100, by recompiling the F<perl> binary, setting the C
-pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
-
-=item *
-
-C<Illegal character in prototype> warning is now more precise
-when reporting illegal characters after _
-
-=item *
-
-mro merging error messages are now very similar to those produced by
-L<Algorithm::C3>.
-
-=item *
-
-Amelioration of the error message "Unrecognized character %s in column %d"
-
-Changes the error message to "Unrecognized character %s; marked by E<lt>--
-HERE after %sE<lt>-- HERE near column %d". This should make it a little
-simpler to spot and correct the suspicious character.
-
-=item *
-
-Perl now explicitly points to C<$.> when it causes an uninitialized
-warning for ranges in scalar context.
-
-=item *
-
-C<split> now warns when called in void context.
-
-=item *
-
-C<printf>-style functions called with too few arguments will now issue the
-warning C<"Missing argument in %s"> [perl #71000]
-
-=item *
-
-Perl now properly returns a syntax error instead of segfaulting
-if C<each>, C<keys>, or C<values> is used without an argument.
-
-=item *
-
-C<tell()> now fails properly if called without an argument and when no
-previous file was read.
-
-C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
-the 5.8.x behaviour.
-
-=item *
-
-C<overload> no longer implicitly unsets fallback on repeated 'use
-overload' lines.
-
-=item *
-
-POSIX::strftime() can now handle Unicode characters in the format string.
-
-=item *
-
-The C<syntax> category was removed from 5 warnings that should only be in
-C<deprecated>.
-
-=item *
-
-Three fatal C<pack>/C<unpack> error messages have been normalized to
-C<panic: %s>
-
-=item *
-
-C<Unicode character is illegal> has been rephrased to be more accurate
-
-It now reads C<Unicode non-character is illegal in interchange> and the
-perldiag documentation has been expanded a bit.
-
-=item *
-
-Currently, all but the first of the several characters that the
-C<charnames> handler may return are discarded when used in a regular
-expression pattern bracketed character class. If this happens then the
-warning C<Using just the first character returned by \N{} in character
-class> will be issued.
-
-=item *
-
-The warning C<Missing right brace on \N{} or unescaped left brace after
-\N. Assuming the latter> will be issued if Perl encounters a C<\N{>
-but doesn't find a matching C<}>. In this case Perl doesn't know if it
-was mistakenly omitted, or if "match non-newline" followed by "match
-a C<{>" was desired. It assumes the latter because that is actually a
-valid interpretation as written, unlike the other case. If you meant
-the former, you need to add the matching right brace. If you did mean
-the latter, you can silence this warning by writing instead C<\N\{>.
-
-=item *
-
-C<gmtime> and C<localtime> called with numbers smaller than they can
-reliably handle will now issue the warnings C<gmtime(%.0f) too small>
-and C<localtime(%.0f) too small>.
-
-=back
-
-The following diagnostic messages have been removed:
-
-=over 4
-
-=item *
-
-C<Runaway format>
-
-=item *
-
-C<Can't locate package %s for the parents of %s>
-
-In general this warning it only got produced in
-conjunction with other warnings, and removing it allowed an ISA lookup
-optimisation to be added.
-
-=item *
-
-C<v-string in use/require is non-portable>
-
-=back
-
-=head1 Utility Changes
-
-=over 4
-
-=item *
-
-F<h2ph> now looks in C<include-fixed> too, which is a recent addition
-to gcc's search path.
-
-=item *
-
-F<h2xs> no longer incorrectly treats enum values like macros.
-It also now handles C++ style comments (C<//>) properly in enums.
-
-=item *
-
-F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
-debugger now correctly handles proxy constant subroutines, and
-subroutine stubs.
-
-=item *
-
-F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
-upstream bug tracker URLs. If a user identifies a particular module
-as the topic of their bug report and we're able to divine the URL for
-its upstream bug tracker, perlbug now provide a message to the user
-explaining that the core copies the CPAN version directly, and provide
-the URL for reporting the bug directly to the upstream author.
-
-F<perlbug> no longer reports "Message sent" when it hasn't actually sent
-the message
-
-=item *
-
-F<perlthanks> is a new utility for sending non-bug-reports to the
-authors and maintainers of Perl. Getting nothing but bug reports can
-become a bit demoralising. If Perl 5.12 works well for you, please try
-out F<perlthanks>. It will make the developers smile.
-
-=item *
-
-Perl's developers have fixed bugs in F<a2p> having to do with the
-C<match()> operator in list context. Additionally, F<a2p> no longer
-generates code that uses the C<$[> variable.
-
-=back
-
-=head1 Selected Bug Fixes
-
-=over 4
-
-=item *
-
-U+0FFFF is now a legal character in regular expressions.
-
-=item *
-
-pp_qr now always returns a new regexp SV. Resolves RT #69852.
-
-Instead of returning a(nother) reference to the (pre-compiled) regexp
-in the optree, use reg_temp_copy() to create a copy of it, and return a
-reference to that. This resolves issues about Regexp::DESTROY not being
-called in a timely fashion (the original bug tracked by RT #69852), as
-well as bugs related to blessing regexps, and of assigning to regexps,
-as described in correspondence added to the ticket.
-
-It transpires that we also need to undo the SvPVX() sharing when ithreads
-cloning a Regexp SV, because mother_re is set to NULL, instead of a
-cloned copy of the mother_re. This change might fix bugs with regexps
-and threads in certain other situations, but as yet neither tests nor
-bug reports have indicated any problems, so it might not actually be an
-edge case that it's possible to reach.
-
-=item *
-
-Several compilation errors and segfaults when perl was built with C<-Dmad>
-were fixed.
-
-=item *
-
-Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
-
-=item *
-
-C<-t> should only return TRUE for file handles connected to a TTY
-
-The Microsoft C version of C<isatty()> returns TRUE for all character mode
-devices, including the F</dev/null>-style "nul" device and printers like
-"lpt1".
-
-=item *
-
-Fixed a regression caused by commit fafafbaf which caused a panic during
-parameter passing [perl #70171]
-
-=item *
-
-On systems which in-place edits without backup files, -i'*' now works as
-the documentation says it does [perl #70802]
-
-=item *
-
-Saving and restoring magic flags no longer loses readonly flag.
-
-=item *
-
-The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
-causes abrupt and total failure.
-
-=item *
-
-Regular expressions compiled with C<qr{}> literals properly set C<$'> when
-matching again.
-
-=item *
-
-Using named subroutines with C<sort> should no longer lead to bus errors
-[perl #71076]
-
-=item *
-
-Numerous bugfixes catch small issues caused by the recently-added Lexer API.
-
-=item *
-
-Smart match against C<@_> sometimes gave false negatives. [perl #71078]
-
-=item *
-
-C<$@> may now be assigned a read-only value (without error or busting
-the stack).
-
-=item *
-
-C<sort> called recursively from within an active comparison subroutine no
-longer causes a bus error if run multiple times. [perl #71076]
-
-=item *
-
-Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
-
-=item *
-
-@_ and $_ no longer leak under threads (RT #34342 and #41138, also
-#70602, #70974)
-
-=item *
-
-C<-I> on shebang line now adds directories in front of @INC
-as documented, and as does C<-I> when specified on the command-line.
-
-=item *
-
-C<kill> is now fatal when called on non-numeric process identifiers.
-Previously, an C<undef> process identifier would be interpreted as a
-request to kill process 0, which would terminate the current process
-group on POSIX systems. Since process identifiers are always integers,
-killing a non-numeric process is now fatal.
-
-=item *
-
-5.10.0 inadvertently disabled an optimisation, which caused a measurable
-performance drop in list assignment, such as is often used to assign
-function parameters from C<@_>. The optimisation has been re-instated, and
-the performance regression fixed. (This fix is also present in 5.10.1)
-
-=item *
-
-Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
-
-=item *
-
-Some potential coredumps in PerlIO fixed [RT #57322,54828].
-
-=item *
-
-The debugger now works with lvalue subroutines.
-
-=item *
-
-The debugger's C<m> command was broken on modules that defined constants
-[RT #61222].
-
-=item *
-
-C<crypt> and string complement could return tainted values for untainted
-arguments [RT #59998].
-
-=item *
-
-The C<-i>I<.suffix> command-line switch now recreates the file using
-restricted permissions, before changing its mode to match the original
-file. This eliminates a potential race condition [RT #60904].
-
-=item *
-
-On some Unix systems, the value in C<$?> would not have the top bit set
-(C<$? & 128>) even if the child core dumped.
-
-=item *
-
-Under some circumstances, C<$^R> could incorrectly become undefined
-[RT #57042].
-
-=item *
-
-In the XS API, various hash functions, when passed a pre-computed hash where
-the key is UTF-8, might result in an incorrect lookup.
-
-=item *
-
-XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
-[RT #57176].
-
-=item *
-
-C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
-didn't exist, even if the object's C<@ISA> contained C<Foo>.
-
-=item *
-
-Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
-C<@ISA>, have been found and fixed.
-
-=item *
-
-Bitwise operations on references could crash the interpreter, e.g.
-C<$x=\$y; $x |= "foo"> [RT #54956].
-
-=item *
-
-Patterns including alternation might be sensitive to the internal UTF-8
-representation, e.g.
-
- my $byte = chr(192);
- my $utf8 = chr(192); utf8::upgrade($utf8);
- $utf8 =~ /$byte|X}/i; # failed in 5.10.0
-
-=item *
-
-Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
-effect), double-quoted literal strings could be corrupted where a C<\xNN>,
-C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
-greater than 255 [RT #59908].
-
-=item *
-
-C<B::Deparse> failed to correctly deparse various constructs:
-C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
-C<sub foo(_)> [RT #62484].
-
-=item *
-
-Using C<setpgrp> with no arguments could corrupt the perl stack.
-
-=item *
-
-The block form of C<eval> is now specifically trappable by C<Safe> and
-C<ops>. Previously it was erroneously treated like string C<eval>.
-
-=item *
-
-In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
-match operator (C<~~>) [RT #63854].
-
-=item *
-
-In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
-C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
-
- ("ab" x 32768) =~ /^(ab)*$/
-
-=item *
-
-C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
-
-=item *
-
-Using C<next> or C<last> to exit a C<given> block no longer produces a
-spurious warning like the following:
-
- Exiting given via last at foo.pl line 123
-
-=item *
-
-Assigning a format to a glob could corrupt the format; e.g.:
-
- *bar=*foo{FORMAT}; # foo format now bad
-
-=item *
-
-Attempting to coerce a typeglob to a string or number could cause an
-assertion failure. The correct error message is now generated,
-C<Can't coerce GLOB to I<$type>>.
-
-=item *
-
-Under C<use filetest 'access'>, C<-x> was using the wrong access
-mode. This has been fixed [RT #49003].
-
-=item *
-
-C<length> on a tied scalar that returned a Unicode value would not be
-correct the first time. This has been fixed.
-
-=item *
-
-Using an array C<tie> inside in array C<tie> could SEGV. This has been
-fixed. [RT #51636]
-
-=item *
-
-A race condition inside C<PerlIOStdio_close()> has been identified and
-fixed. This used to cause various threading issues, including SEGVs.
-
-=item *
-
-In C<unpack>, the use of C<()> groups in scalar context was internally
-placing a list on the interpreter's stack, which manifested in various
-ways, including SEGVs. This is now fixed [RT #50256].
-
-=item *
-
-Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
-These have all been fixed.
-
-=item *
-
-A 5.10.0 optimisation to clear the temporary stack within the implicit
-loop of C<s///ge> has been reverted, as it turned out to be the cause of
-obscure bugs in seemingly unrelated parts of the interpreter [commit
-ef0d4e17921ee3de].
-
-=item *
-
-The line numbers for warnings inside C<elsif> are now correct.
-
-=item *
-
-The C<..> operator now works correctly with ranges whose ends are at or
-close to the values of the smallest and largest integers.
-
-=item *
-
-C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
-This has been fixed [RT #54828].
-
-=item *
-
-An off-by-one error meant that C<index $str, ...> was effectively being
-executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
-
-=item *
-
-Various leaks associated with named captures in regexes have been fixed
-[RT #57024].
-
-=item *
-
-A weak reference to a hash would leak. This was affecting C<DBI>
-[RT #56908].
-
-=item *
-
-Using (?|) in a regex could cause a segfault [RT #59734].
-
-=item *
-
-Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
-
-=item *
-
-Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
-unaligned 64-bit access on the SPARC architecture [RT #60574].
-
-=item *
-
-In the 5.10.0 release, C<inc_version_list> would incorrectly list
-C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
-[RT #67628].
-
-=item *
-
-In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
-[RT #52552].
-
-=item *
-
-In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
-C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
-[RT #62666].
-
-=item *
-
-In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
-missed (method cache issue) [RT #60220,60232].
-
-=item *
-
-In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
-cause a memory leak [RT #63110].
-
-=item *
-
-C<-C> on the shebang (C<#!>) line is once more permitted if it is also
-specified on the command line. C<-C> on the shebang line used to be a
-silent no-op I<if> it was not also on the command line, so perl 5.10.0
-disallowed it, which broke some scripts. Now perl checks whether it is
-also on the command line and only dies if it is not [RT #67880].
-
-=item *
-
-In 5.10.0, certain types of re-entrant regular expression could crash,
-or cause the following assertion failure [RT #60508]:
-
- Assertion rx->sublen >= (s - rx->subbeg) + i failed
-
-=item *
-
-Perl now includes previously missing files from the Unicode Character
-Database.
-
-=item *
-
-Perl now honors C<TMPDIR> when opening an anonymous temporary file.
-
-=back
-
-
-=head1 Platform Specific Changes
-
-Perl is incredibly portable. In general, if a platform has a C compiler,
-someone has ported Perl to it (or will soon). We're happy to announce
-that Perl 5.12 includes support for several new platforms. At the same
-time, it's time to bid farewell to some (very) old friends.
-
-=head2 New Platforms
-
-=over
-
-=item Haiku
-
-Perl's developers have merged patches from Haiku's maintainers. Perl
-should now build on Haiku.
-
-=item MirOS BSD
-
-Perl should now build on MirOS BSD.
-
-=back
-
-=head2 Discontinued Platforms
-
-=over
-
-=item Domain/OS
-
-=item MiNT
-
-=item Tenon MachTen
-
-=back
-
-=head2 Updated Platforms
-
-=over 4
-
-=item AIX
-
-=over 4
-
-=item *
-
-Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
-F<libbsd>.
-
-=item *
-
-Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
-installed. The F<libgdbm> is delivered as an optional package with the
-AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
-
-=item *
-
-Hints changes mean that AIX 4.2 should work again.
-
-=back
-
-=item Cygwin
-
-=over 4
-
-=item *
-
-Perl now supports IPv6 on Cygwin 1.7 and newer.
-
-=item *
-
-On Cygwin we now strip the last number from the DLL. This has been the
-behaviour in the cygwin.com build for years. The hints files have been
-updated.
-
-=back
-
-=item Darwin (Mac OS X)
-
-=over 4
-
-=item *
-
-Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
-as it's still buggy.
-
-=item *
-
-Correct infelicities in the regexp used to identify buggy locales
-on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
-
-=back
-
-=item DragonFly BSD
-
-=over 4
-
-=item *
-
-Fix thread library selection [perl #69686]
-
-=back
-
-=item FreeBSD
-
-=over 4
-
-=item *
-
-The hints files now identify the correct threading libraries on FreeBSD 7
-and later.
-
-=back
-
-=item Irix
-
-=over 4
-
-=item *
-
-We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
-C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
-
-=back
-
-=item NetBSD
-
-=over 4
-
-=item *
-
-Hints now supports versions 5.*.
-
-=back
-
-=item OpenVMS
-
-=over 4
-
-=item *
-
-C<-UDEBUGGING> is now the default on VMS.
-
-Like it has been everywhere else for ages and ages. Also make command-line
-selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
-the only way to turn it off was by saying no in answer to the interactive
-question.
-
-=item *
-
-The default pipe buffer size on VMS has been updated to 8192 on 64-bit
-systems.
-
-=item *
-
-Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
-if C<$/> was set to a numeric reference (to indicate record-style reads).
-This is now fixed.
-
-=item *
-
-VMS now supports C<getgrgid>.
-
-=item *
-
-Many improvements and cleanups have been made to the VMS file name handling
-and conversion code.
-
-=item *
-
-Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
-status in a VMS condition value for better interaction with GNV's bash
-shell and other utilities that depend on POSIX exit values. See
-L<perlvms/"$?"> for details.
-
-=item *
-
-C<File::Copy> now detects Unix compatibility mode on VMS.
-
-=back
-
-=item Stratus VOS
-
-=over 4
-
-=item *
-
-Various changes from Stratus have been merged in.
-
-=back
-
-=item Symbian
-
-=over 4
-
-=item *
-
-There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
-
-=back
-
-=item Windows
-
-=over 4
-
-=item *
-
-Perl 5.12 supports Windows 2000 and later. The supporting code for
-legacy versions of Windows is still included, but will be removed
-during the next development cycle.
-
-=item *
-
-Initial support for building Perl with MinGW-w64 is now available.
-
-=item *
-
-F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
-settings for Windows Vista and later. Without this setting Windows
-would treat F<perl.exe> as a legacy application and apply various
-heuristics like redirecting access to protected file system areas
-(like the "Program Files" folder) to the users "VirtualStore"
-instead of generating a proper "permission denied" error.
-
-The manifest resource also requests the Microsoft Common-Controls
-version 6.0 (themed controls introduced in Windows XP). Check out the
-Win32::VisualStyles module on CPAN to switch back to old style
-unthemed controls for legacy applications.
-
-=item *
-
-The C<-t> filetest operator now only returns true if the filehandle
-is connected to a console window. In previous versions of Perl it
-would return true for all character mode devices, including F<NUL>
-and F<LPT1>.
-
-=item *
-
-The C<-p> filetest operator now works correctly, and the
-Fcntl::S_IFIFO constant is defined when Perl is compiled with
-Microsoft Visual C. In previous Perl versions C<-p> always
-returned a false value, and the Fcntl::S_IFIFO constant
-was not defined.
-
-This bug is specific to Microsoft Visual C and never affected
-Perl binaries built with MinGW.
-
-=item *
-
-The socket error codes are now more widely supported: The POSIX
-module will define the symbolic names, like POSIX::EWOULDBLOCK,
-and stringification of socket error codes in $! works as well
-now;
-
- C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
- A non-blocking socket operation could not be completed immediately.
-
-=item *
-
-flock() will now set sensible error codes in $!. Previous Perl versions
-copied the value of $^E into $!, which caused much confusion.
-
-=item *
-
-select() now supports all empty C<fd_set>s more correctly.
-
-=item *
-
-C<'.\foo'> and C<'..\foo'> were treated differently than
-C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
-
-=item *
-
-Improved message window handling means that C<alarm> and C<kill> messages
-will no longer be dropped under race conditions.
-
-=item *
-
-Various bits of Perl's build infrastructure are no longer converted to
-win32 line endings at release time. If this hurts you, please report the
-problem with the L<perlbug> program included with perl.
-
-=back
-
-=back
-
-
-=head1 Known Problems
-
-This is a list of some significant unfixed bugs, which are regressions
-from either 5.10.x or 5.8.x.
-
-=over 4
-
-=item *
-
-Some CPANPLUS tests may fail if there is a functioning file
-F<../../cpanp-run-perl> outside your build directory. The failure
-shouldn't imply there's a problem with the actual functional
-software. The bug is already fixed in [RT #74188] and is scheduled for
-inclusion in perl-v5.12.1.
-
-=item *
-
-C<List::Util::first> misbehaves in the presence of a lexical C<$_>
-(typically introduced by C<my $_> or implicitly by C<given>). The variable
-which gets set for each iteration is the package variable C<$_>, not the
-lexical C<$_> [RT #67694].
-
-A similar issue may occur in other modules that provide functions which
-take a block as their first argument, like
-
- foo { ... $_ ...} list
-
-=item *
-
-Some regexes may run much more slowly when run in a child thread compared
-with the thread the pattern was compiled into [RT #55600].
-
-=item *
-
-Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
-will appear to hang as they get into a very long running loop [RT #72998].
-
-=item *
-
-Several porters have reported mysterious crashes when Perl's entire
-test suite is run after a build on certain Windows 2000 systems. When
-run by hand, the individual tests reportedly work fine.
-
-=back
-
-=head1 Errata
-
-=over
-
-=item *
-
-This one is actually a change introduced in 5.10.0, but it was missed
-from that release's perldelta, so it is mentioned here instead.
-
-A bugfix related to the handling of the C</m> modifier and C<qr> resulted
-in a change of behaviour between 5.8.x and 5.10.0:
-
- # matches in 5.8.x, doesn't match in 5.10.0
- $re = qr/^bar/; "foo\nbar" =~ /$re/m;
-
-=back
-
-=head1 Acknowledgements
-
-Perl 5.12.0 represents approximately two years of development since
-Perl 5.10.0 and contains over 750,000 lines of changes across over
-3,000 files from over 200 authors and committers.
-
-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 5.12.0:
-
-Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
-Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
-Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
-andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
-Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
-Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
-Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
-Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
-Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
-Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
-David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
-Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
-Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
-Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
-Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
-Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
-Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
-Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
-Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
-John Peacock, John Peacock via RT, John P. Linderman, John Wright,
-Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
-Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
-Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
-Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
-Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
-G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
-Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
-Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
-Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
-Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
-Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
-Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
-Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
-Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
-Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
-Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
-The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
-Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
-Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
-Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
-
-This is woefully incomplete as it's automatically generated from version
-control history. In particular, it doesn't include the names of the
-(very much appreciated) contributors who reported issues in previous
-versions of Perl that helped make Perl 5.12.0 better. For a more complete
-list of all of Perl's historical contributors, please see the C<AUTHORS>
-file in the Perl 5.12.0 distribution.
-
-Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
-deserve special thanks for their brilliant and substantive ongoing
-contributions. Nicholas personally authored over 30% of the patches
-since 5.10.0. Rafael comes in second in patch authorship with 11%,
-but is first by a long shot in committing patches authored by others,
-pushing 44% of the commits since 5.10.0 in this category, often after
-providing considerable coaching to the patch authors. These statistics
-in no way comprise all of their contributions, but express in shorthand
-that we couldn't have done it without them.
-
-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.
-
-=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<http://rt.perl.org/perlbug/>. 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 B<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
-analyzed 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.
-
-L<http://dev.perl.org/perl5/errata.html> for a list of issues
-found after this release, as well as a list of CPAN modules known
-to be incompatible with this release.
-
-=cut