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diff --git a/Master/tlpkg/tlperl/lib/pods/perl5120delta.pod b/Master/tlpkg/tlperl/lib/pods/perl5120delta.pod new file mode 100644 index 00000000000..5d5b401e784 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/pods/perl5120delta.pod @@ -0,0 +1,3200 @@ +=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> is now more flexible + +The C<each> 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 treates 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. + +=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 reprecussions 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<$1> in perlvar.pod has been clarified. + +=item * + +C<\N{U+I<wide hex char>}> is now documented. + +=back + +=head1 Selected Performance Enhancements + +=over 4 + +=item * + +A new internal cache means that C<isa()> will often be faster. + +=item * + +The implementation of C<C3> Method Resolution Order has been +optimised - linearisation for classes with single inheritance is 40% +faster. Performance for multiple inheritance is unchanged. + +=item * + +Under C<use locale>, the locale-relevant information is now cached on +read-only values, such as the list returned by C<keys %hash>. This makes +operations such as C<sort keys %hash> in the scope of C<use locale> +much faster. + +=item * + +Empty C<DESTROY> methods are no longer called. + +=item * + +C<Perl_sv_utf8_upgrade()> is now faster. + +=item * + +C<keys> on empty hash is now faster. + +=item * + +C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>. + +=item * + +The string repetition operator (C<$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<wide hex char>}> in its +definition in UTF-8 format. (This was true previously for all occurences +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 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 |