5 perl5120delta - what is new for perl v5.12.0
9 This document describes differences between the 5.10.0 release and the
12 Many of the bug fixes in 5.12.0 are already included in the 5.10.1
15 You can see the list of those changes in the 5.10.1 release notes
19 =head1 Core Enhancements
21 =head2 New C<package NAME VERSION> syntax
23 This new syntax allows a module author to set the $VERSION of a namespace
24 when the namespace is declared with 'package'. It eliminates the need
25 for C<our $VERSION = ...> and similar constructs. E.g.
27 package Foo::Bar 1.23;
28 # $Foo::Bar::VERSION == 1.23
30 There are several advantages to this:
36 C<$VERSION> is parsed in exactly the same way as C<use NAME VERSION>
40 C<$VERSION> is set at compile time
44 C<$VERSION> is a version object that provides proper overloading of
45 comparison operators so comparing C<$VERSION> to decimal (1.23) or
46 dotted-decimal (v1.2.3) version numbers works correctly.
50 Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
54 As it requires VERSION to be a numeric literal or v-string
55 literal, it can be statically parsed by toolchain modules
56 without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
60 It does not break old code with only C<package NAME>, but code that uses
61 C<package NAME VERSION> will need to be restricted to perl 5.12.0 or newer
62 This is analogous to the change to C<open> from two-args to three-args.
63 Users requiring the latest Perl will benefit, and perhaps after several
64 years, it will become a standard practice.
67 However, C<package NAME VERSION> requires a new, 'strict' version
68 number format. See L</"Version number formats"> for details.
71 =head2 The C<...> operator
73 A new operator, C<...>, nicknamed the Yada Yada operator, has been added.
74 It is intended to mark placeholder code that is not yet implemented.
75 See L<perlop/"Yada Yada Operator">.
77 =head2 Implicit strictures
79 Using the C<use VERSION> syntax with a version number greater or equal
80 to 5.11.0 will lexically enable strictures just like C<use strict>
81 would do (in addition to enabling features.) The following:
90 =head2 Unicode improvements
92 Perl 5.12 comes with Unicode 5.2, the latest version available to
93 us at the time of release. This version of Unicode was released in
94 October 2009. See L<http://www.unicode.org/versions/Unicode5.2.0> for
95 further details about what's changed in this version of the standard.
96 See L<perlunicode> for instructions on installing and using other versions
99 Additionally, Perl's developers have significantly improved Perl's Unicode
100 implementation. For full details, see L</Unicode overhaul> below.
102 =head2 Y2038 compliance
104 Perl's core time-related functions are now Y2038 compliant. (It may not mean much to you, but your kids will love it!)
106 =head2 qr overloading
108 It is now possible to overload the C<qr//> operator, that is,
109 conversion to regexp, like it was already possible to overload
110 conversion to boolean, string or number of objects. It is invoked when
111 an object appears on the right hand side of the C<=~> operator or when
112 it is interpolated into a regexp. See L<overload>.
114 =head2 Pluggable keywords
116 Extension modules can now cleanly hook into the Perl parser to define
117 new kinds of keyword-headed expression and compound statement. The
118 syntax following the keyword is defined entirely by the extension. This
119 allows a completely non-Perl sublanguage to be parsed inline, with the
120 correct ops cleanly generated.
122 See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core
123 source distribution also includes a new module
124 L<XS::APItest::KeywordRPN>, which implements reverse Polish notation
125 arithmetic via pluggable keywords. This module is mainly used for test
126 purposes, and is not normally installed, but also serves as an example
127 of how to use the new mechanism.
129 Perl's developers consider this feature to be experimental. We may remove
130 it or change it in a backwards-incompatible way in Perl 5.14.
132 =head2 APIs for more internals
134 The lowest layers of the lexer and parts of the pad system now have C
135 APIs available to XS extensions. These are necessary to support proper
136 use of pluggable keywords, but have other uses too. The new APIs are
137 experimental, and only cover a small proportion of what would be
138 necessary to take full advantage of the core's facilities in these
139 areas. It is intended that the Perl 5.13 development cycle will see the
140 addition of a full range of clean, supported interfaces.
142 Perl's developers consider this feature to be experimental. We may remove
143 it or change it in a backwards-incompatible way in Perl 5.14.
145 =head2 Overridable function lookup
147 Where an extension module hooks the creation of rv2cv ops to modify the
148 subroutine lookup process, this now works correctly for bareword
149 subroutine calls. This means that prototypes on subroutines referenced
150 this way will be processed correctly. (Previously bareword subroutine
151 names were initially looked up, for parsing purposes, by an unhookable
152 mechanism, so extensions could only properly influence subroutine names
153 that appeared with an C<&> sigil.)
155 =head2 A proper interface for pluggable Method Resolution Orders
157 As of Perl 5.12.0 there is a new interface for plugging and using method
158 resolution orders other than the default linear depth first search.
159 The C3 method resolution order added in 5.10.0 has been re-implemented as
160 a plugin, without changing its Perl-space interface. See L<perlmroapi> for
165 =head2 C<\N> experimental regex escape
167 Perl now supports C<\N>, a new regex escape which you can think of as
168 the inverse of C<\n>. It will match any character that is not a newline,
169 independently from the presence or absence of the single line match
170 modifier C</s>. It is not usable within a character class. C<\N{3}>
171 means to match 3 non-newlines; C<\N{5,}> means to match at least 5.
172 C<\N{NAME}> still means the character or sequence named C<NAME>, but
173 C<NAME> no longer can be things like C<3>, or C<5,>.
175 This will break a L<custom charnames translator|charnames/CUSTOM
176 TRANSLATORS> which allows numbers for character names, as C<\N{3}> will
177 now mean to match 3 non-newline characters, and not the character whose
178 name is C<3>. (No name defined by the Unicode standard is a number,
179 so only custom translators might be affected.)
181 Perl's developers are somewhat concerned about possible user confusion
182 with the existing C<\N{...}> construct which matches characters by their
183 Unicode name. Consequently, this feature is experimental. We may remove
184 it or change it in a backwards-incompatible way in Perl 5.14.
186 =head2 DTrace support
188 Perl now has some support for DTrace. See "DTrace support" in F<INSTALL>.
190 =head2 Support for C<configure_requires> in CPAN module metadata
192 Both C<CPAN> and C<CPANPLUS> now support the C<configure_requires>
193 keyword in the F<META.yml> metadata file included in most recent CPAN
194 distributions. This allows distribution authors to specify configuration
195 prerequisites that must be installed before running F<Makefile.PL>
198 See the documentation for C<ExtUtils::MakeMaker> or C<Module::Build> for
199 more on how to specify C<configure_requires> when creating a distribution
202 =head2 C<each>, C<keys>, C<values> are now more flexible
204 The C<each>, C<keys>, C<values> function can now operate on arrays.
206 =head2 C<when> as a statement modifier
208 C<when> is now allowed to be used as a statement modifier.
210 =head2 C<$,> flexibility
212 The variable C<$,> may now be tied.
214 =head2 // in when clauses
216 // now behaves like || in when clauses
218 =head2 Enabling warnings from your shell environment
220 You can now set C<-W> from the C<PERL5OPT> environment variable
222 =head2 C<delete local>
224 C<delete local> now allows you to locally delete a hash entry.
226 =head2 New support for Abstract namespace sockets
228 Abstract namespace sockets are Linux-specific socket type that live in
229 AF_UNIX family, slightly abusing it to be able to use arbitrary
230 character arrays as addresses: They start with nul byte and are not
231 terminated by nul byte, but with the length passed to the socket()
234 =head2 32-bit limit on substr arguments removed
236 The 32-bit limit on C<substr> arguments has now been removed. The full
237 range of the system's signed and unsigned integers is now available for
238 the C<pos> and C<len> arguments.
240 =head1 Potentially Incompatible Changes
242 =head2 Deprecations warn by default
244 Over the years, Perl's developers have deprecated a number of language
245 features for a variety of reasons. Perl now defaults to issuing a
246 warning if a deprecated language feature is used. Many of the deprecations
247 Perl now warns you about have been deprecated for many years. You can
248 find a list of what was deprecated in a given release of Perl in the
249 C<perl5xxdelta.pod> file for that release.
251 To disable this feature in a given lexical scope, you should use C<no
252 warnings 'deprecated';> For information about which language features
253 are deprecated and explanations of various deprecation warnings, please
254 see L<perldiag>. See L</Deprecations> below for the list of features
255 and modules Perl's developers have deprecated as part of this release.
257 =head2 Version number formats
259 Acceptable version number formats have been formalized into "strict" and
260 "lax" rules. C<package NAME VERSION> takes a strict version number.
261 C<UNIVERSAL::VERSION> and the L<version> object constructors take lax
262 version numbers. Providing an invalid version will result in a fatal
263 error. The version argument in C<use NAME VERSION> is first parsed as a
264 numeric literal or v-string and then passed to C<UNIVERSAL::VERSION>
265 (and must then pass the "lax" format test).
267 These formats are documented fully in the L<version> module. To a first
268 approximation, a "strict" version number is a positive decimal number
269 (integer or decimal-fraction) without exponentiation or else a
270 dotted-decimal v-string with a leading 'v' character and at least three
271 components. A "lax" version number allows v-strings with fewer than
272 three components or without a leading 'v'. Under "lax" rules, both
273 decimal and dotted-decimal versions may have a trailing "alpha"
274 component separated by an underscore character after a fractional or
275 dotted-decimal component.
277 The L<version> module adds C<version::is_strict> and C<version::is_lax>
278 functions to check a scalar against these rules.
280 =head2 @INC reorganization
282 In C<@INC>, C<ARCHLIB> and C<PRIVLIB> now occur after the current
283 version's C<site_perl> and C<vendor_perl>. Modules installed into
284 C<site_perl> and C<vendor_perl> will now be loaded in preference to
285 those installed in C<ARCHLIB> and C<PRIVLIB>.
288 =head2 REGEXPs are now first class
290 Internally, Perl now treats compiled regular expressions (such as
291 those created with C<qr//>) as first class entities. Perl modules which
292 serialize, deserialize or otherwise have deep interaction with Perl's
293 internal data structures need to be updated for this change. Most
294 affected CPAN modules have already been updated as of this writing.
296 =head2 Switch statement changes
298 The C<given>/C<when> switch statement handles complex statements better
299 than Perl 5.10.0 did (These enhancements are also available in
300 5.10.1 and subsequent 5.10 releases.) There are two new cases where
301 C<when> now interprets its argument as a boolean, instead of an
302 expression to be used in a smart match:
306 =item flip-flop operators
308 The C<..> and C<...> flip-flop operators are now evaluated in boolean
309 context, following their usual semantics; see L<perlop/"Range Operators">.
311 Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
312 whether a given value is an integer between 1 and 10; you should use
313 C<when ([1..10])> instead (note the array reference).
315 However, contrary to 5.10.0, evaluating the flip-flop operators in
316 boolean context ensures it can now be useful in a C<when()>, notably
317 for implementing bistable conditions, like in:
319 when (/^=begin/ .. /^=end/) {
323 =item defined-or operator
325 A compound expression involving the defined-or operator, as in
326 C<when (expr1 // expr2)>, will be treated as boolean if the first
327 expression is boolean. (This just extends the existing rule that applies
328 to the regular or operator, as in C<when (expr1 || expr2)>.)
332 =head2 Smart match changes
334 Since Perl 5.10.0, Perl's developers have made a number of changes to
335 the smart match operator. These, of course, also alter the behaviour
336 of the switch statements where smart matching is implicitly used.
337 These changes were also made for the 5.10.1 release, and will remain in
338 subsequent 5.10 releases.
340 =head3 Changes to type-based dispatch
342 The smart match operator C<~~> is no longer commutative. The behaviour of
343 a smart match now depends primarily on the type of its right hand
344 argument. Moreover, its semantics have been adjusted for greater
345 consistency or usefulness in several cases. While the general backwards
346 compatibility is maintained, several changes must be noted:
352 Code references with an empty prototype are no longer treated specially.
353 They are passed an argument like the other code references (even if they
354 choose to ignore it).
358 C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
359 returns a true value for each key of the hash (or element of the
360 array), instead of passing the whole hash or array as a reference to
365 Due to the commutativity breakage, code references are no longer
366 treated specially when appearing on the left of the C<~~> operator,
367 but like any vulgar scalar.
371 C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
372 hash). No implicit conversion to C<""> is done (as was the case in perl
377 C<$scalar ~~ @array> now always distributes the smart match across the
378 elements of the array. It's true if one element in @array verifies
379 C<$scalar ~~ $element>. This is a generalization of the old behaviour
380 that tested whether the array contained the scalar.
384 The full dispatch table for the smart match operator is given in
385 L<perlsyn/"Smart matching in detail">.
387 =head3 Smart match and overloading
389 According to the rule of dispatch based on the rightmost argument type,
390 when an object overloading C<~~> appears on the right side of the
391 operator, the overload routine will always be called (with a 3rd argument
392 set to a true value, see L<overload>.) However, when the object will
393 appear on the left, the overload routine will be called only when the
394 rightmost argument is a simple scalar. This way, distributivity of smart
395 match across arrays is not broken, as well as the other behaviours with
396 complex types (coderefs, hashes, regexes). Thus, writers of overloading
397 routines for smart match mostly need to worry only with comparing
398 against a scalar, and possibly with stringification overloading; the
399 other common cases will be automatically handled consistently.
401 C<~~> will now refuse to work on objects that do not overload it (in order
402 to avoid relying on the object's underlying structure). (However, if the
403 object overloads the stringification or the numification operators, and
404 if overload fallback is active, it will be used instead, as usual.)
406 =head2 Other potentially incompatible changes
412 The definitions of a number of Unicode properties have changed to match
413 those of the current Unicode standard. These are listed above under
414 L</Unicode overhaul>. This change may break code that expects the old
419 The boolkeys op has moved to the group of hash ops. This breaks binary
424 Filehandles are now always blessed into C<IO::File>.
426 The previous behaviour was to bless Filehandles into L<FileHandle>
427 (an empty proxy class) if it was loaded into memory and otherwise
428 to bless them into C<IO::Handle>.
432 The semantics of C<use feature :5.10*> have changed slightly.
433 See L</"Modules and Pragmata"> for more information.
437 Perl's developers now use git, rather than Perforce. This should be
438 a purely internal change only relevant to people actively working on
439 the core. However, you may see minor difference in perl as a consequence
440 of the change. For example in some of details of the output of C<perl
441 -V>. See L<perlrepository> for more information.
445 As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
446 C<Test::Harness::Straps> module has been removed.
447 See L</"Modules and Pragmata"> for more details.
451 As part of the C<ExtUtils::MakeMaker> upgrade, the
452 C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
453 have been removed from this distribution.
457 C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
461 C<length undef> now returns undef.
465 Unsupported private C API functions are now declared "static" to prevent
466 leakage to Perl's public API.
470 To support the bootstrapping process, F<miniperl> no longer builds with
471 UTF-8 support in the regexp engine.
473 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
474 Without this there's a bootstrapping problem, as miniperl can't load
475 the UTF-8 components of the regexp engine, because they're not yet built.
479 F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
480 C<$ENV{PERL5LIB}>, and "C<.>"
484 A space or a newline is now required after a C<"#line XXX"> directive.
488 Tied filehandles now have an additional method EOF which provides the
493 To better match all other flow control statements, C<foreach> may no
494 longer be used as an attribute.
498 Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
499 now been removed. The CPAN module C<< Filter::cpp >> can be used as an
507 From time to time, Perl's developers find it necessary to deprecate
508 features or modules we've previously shipped as part of the core
509 distribution. We are well aware of the pain and frustration that a
510 backwards-incompatible change to Perl can cause for developers building
511 or maintaining software in Perl. You can be sure that when we deprecate
512 a functionality or syntax, it isn't a choice we make lightly. Sometimes,
513 we choose to deprecate functionality or syntax because it was found to
514 be poorly designed or implemented. Sometimes, this is because they're
515 holding back other features or causing performance problems. Sometimes,
516 the reasons are more complex. Wherever possible, we try to keep deprecated
517 functionality available to developers in its previous form for at least
518 one major release. So long as a deprecated feature isn't actively
519 disrupting our ability to maintain and extend Perl, we'll try to leave
520 it in place as long as possible.
522 The following items are now deprecated:
528 C<suidperl> is no longer part of Perl. It used to provide a mechanism to
529 emulate setuid permission bits on systems that don't support it properly.
531 =item Use of C<:=> to mean an empty attribute list
533 An accident of Perl's parser meant that these constructions were all
540 with the C<:> being treated as the start of an attribute list, which
541 ends before the C<=>. As whitespace is not significant here, all are
542 parsed as an empty attribute list, hence all the above are equivalent
543 to, and better written as
547 because no attribute processing is done for an empty list.
549 As is, this meant that C<:=> cannot be used as a new token, without
550 silently changing the meaning of existing code. Hence that particular
551 form is now deprecated, and will become a syntax error. If it is
552 absolutely necessary to have empty attribute lists (for example,
553 because of a code generator) then avoid the warning by adding a space
556 =item C<< UNIVERSAL->import() >>
558 The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
559 pass import arguments to a C<use UNIVERSAL> statement will result in a
562 =item Use of "goto" to jump into a construct
564 Using C<goto> to jump from an outer scope into an inner scope is now
565 deprecated. This rare use case was causing problems in the
566 implementation of scopes.
568 =item Custom character names in \N{name} that don't look like names
570 In C<\N{I<name>}>, I<name> can be just about anything. The standard
571 Unicode names have a very limited domain, but a custom name translator
572 could create names that are, for example, made up entirely of punctuation
573 symbols. It is now deprecated to make names that don't begin with an
574 alphabetic character, and aren't alphanumeric or contain other than
575 a very few other characters, namely spaces, dashes, parentheses
576 and colons. Because of the added meaning of C<\N> (See C<L</\N>
577 experimental regex escape>), names that look like curly brace -enclosed
578 quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
579 4 non-newlines; before a custom name C<3,4> could have been created.
581 =item Deprecated Modules
583 The following modules will be removed from the core distribution in a
584 future release, and should be installed from CPAN instead. Distributions
585 on CPAN which require these should add them to their prerequisites. The
586 core versions of these modules warnings will issue a deprecation warning.
588 If you ship a packaged version of Perl, either alone or as part of a
589 larger system, then you should carefully consider the repercussions of
590 core module deprecations. You may want to consider shipping your default
591 build of Perl with packages for some or all deprecated modules which
592 install into C<vendor> or C<site> perl library directories. This will
593 inhibit the deprecation warnings.
595 Alternatively, you may want to consider patching F<lib/deprecate.pm>
596 to provide deprecation warnings specific to your packaging system
597 or distribution of Perl, consistent with how your packaging system
598 or distribution manages a staged transition from a release where the
599 installation of a single package provides the given functionality, to
600 a later release where the system administrator needs to know to install
601 multiple packages to get that same functionality.
603 You can silence these deprecation warnings by installing the modules
604 in question from CPAN. To install the latest version of all of them,
605 just install C<Task::Deprecations::5_12>.
611 =item L<Pod::Plainer>
617 Switch is buggy and should be avoided. You may find Perl's new
618 C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
619 statements"> for more information.
623 =item Assignment to $[
625 =item Use of the attribute :locked on subroutines
627 =item Use of "locked" with the attributes pragma
629 =item Use of "unique" with the attributes pragma
633 C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
634 generates a deprecation warning, and it will be removed in a future
635 release. Although listed as part of the API, it was never documented,
636 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
637 core, it has been replaced by a static function.
639 =item Numerous Perl 4-era libraries
641 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
642 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
643 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
644 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
645 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
646 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
647 F<timelocal.pl> are all now deprecated. Earlier, Perl's developers
648 intended to remove these libraries from Perl's core for the 5.14.0 release.
650 During final testing before the release of 5.12.0, several developers
651 discovered current production code using these ancient libraries, some
652 inside the Perl core itself. Accordingly, the pumpking granted them
653 a stay of execution. They will begin to warn about their deprecation
654 in the 5.14.0 release and will be removed in the 5.16.0 release.
659 =head1 Unicode overhaul
661 Perl's developers have made a concerted effort to update Perl to be in
662 sync with the latest Unicode standard. Changes for this include:
664 Perl can now handle every Unicode character property. New documentation,
665 L<perluniprops>, lists all available non-Unihan character properties. By
666 default, perl does not expose Unihan, deprecated or Unicode-internal
667 properties. See below for more details on these; there is also a section
668 in the pod listing them, and explaining why they are not exposed.
670 Perl now fully supports the Unicode compound-style of using C<=>
671 and C<:> in writing regular expressions: C<\p{property=value}> and
672 C<\p{property:value}> (both of which mean the same thing).
674 Perl now fully supports the Unicode loose matching rules for text between
675 the braces in C<\p{...}> constructs. In addition, Perl allows underscores
676 between digits of numbers.
678 Perl now accepts all the Unicode-defined synonyms for properties and
681 C<qr/\X/>, which matches a Unicode logical character, has
682 been expanded to work better with various Asian languages. It
683 now is defined as an I<extended grapheme cluster>. (See
684 L<http://www.unicode.org/reports/tr29/>). Anything matched previously
685 and that made sense will continue to be accepted. Additionally:
691 C<\X> will not break apart a C<S<CR LF>> sequence.
695 C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
700 C<\X> will now always match at least one character, including an initial
701 mark. Marks generally come after a base character, but it is possible in
702 Unicode to have them in isolation, and C<\X> will now handle that case,
703 for example at the beginning of a line, or after a C<ZWSP>. And this is
704 the part where C<\X> doesn't match the things that it used to that don't
705 make sense. Formerly, for example, you could have the nonsensical case
710 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
711 and Lao exception cases.
715 Otherwise, this change should be transparent for the non-affected
718 C<\p{...}> matches using the Canonical_Combining_Class property were
719 completely broken in previous releases of Perl. They should now work
722 Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
723 and a Perl extension had the same name, which led to neither matching
724 all the correct values (with more than 100 mistakes in one, and several
725 thousand in the other). The Perl extension has now been renamed to be
726 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
727 same meaning as was previously intended, namely the union of all the
728 non-canonical Decomposition types, with Unicode C<Compat> being just
731 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
733 C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
734 says they should. This means they each match a few more characters than
737 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
738 means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
739 nor Format (gc=cf) code points. The Format code points represent the
740 biggest possible problem. All but 36 of them are either officially
741 deprecated or strongly discouraged from being used. Of those 36, likely
742 the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
743 WJ, and similar characters, plus bidirectional controls.
745 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
746 5.12, Perl's definition included a number of things that aren't
747 really alpha (all marks) while omitting many that were. The definitions
748 of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
751 C<\p{Word}> no longer incorrectly matches non-word characters such
754 C<\p{Print}> no longer matches the line control characters: Tab, LF,
755 CR, FF, VT, and NEL. This brings it in line with standards and the
758 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
759 means that in addition to the characters it currently matches,
760 C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
761 example U+FF10: FULLWIDTH DIGIT ZERO.
763 The Numeric type property has been extended to include the Unihan
766 There is a new Perl extension, the 'Present_In', or simply 'In',
767 property. This is an extension of the Unicode Age property, but
768 C<\p{In=5.0}> matches any code point whose usage has been determined
769 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
770 added in I<precisely> version 5.0.
772 A number of properties now have the correct values for unassigned
773 code points. The affected properties are Bidi_Class, East_Asian_Width,
774 Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
777 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
778 are now up to date with current Unicode definitions.
780 Earlier versions of Perl erroneously exposed certain properties that
781 are supposed to be Unicode internal-only. Use of these in regular
782 expressions will now generate, if enabled, a deprecation warning message.
783 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
784 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
785 Other_Math, and Other_Uppercase.
787 It is now possible to change which Unicode properties Perl understands
788 on a per-installation basis. As mentioned above, certain properties
789 are turned off by default. These include all the Unihan properties
790 (which should be accessible via the CPAN module Unicode::Unihan) and any
791 deprecated or Unicode internal-only property that Perl has never exposed.
793 The generated files in the C<lib/unicore/To> directory are now more
794 clearly marked as being stable, directly usable by applications. New hash
795 entries in them give the format of the normal entries, which allows for
796 easier machine parsing. Perl can generate files in this directory for
797 any property, though most are suppressed. You can find instructions
798 for changing which are written in L<perluniprops>.
800 =head1 Modules and Pragmata
802 =head2 New Modules and Pragmata
808 C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
809 The bundled version is 2.06_01. Note that in this release, using a string
810 eval when C<autodie> is in effect can cause the autodie behaviour to leak
811 into the surrounding scope. See L<autodie/"BUGS"> for more details.
813 Version 2.06_01 has been added to the Perl core.
815 =item C<Compress::Raw::Bzip2>
817 Version 2.024 has been added to the Perl core.
821 C<overloading> allows you to lexically disable or enable overloading
822 for some or all operations.
824 Version 0.001 has been added to the Perl core.
828 C<parent> establishes an ISA relationship with base classes at compile
829 time. It provides the key feature of C<base> without further unwanted
832 Version 0.223 has been added to the Perl core.
834 =item C<Parse::CPAN::Meta>
836 Version 1.40 has been added to the Perl core.
840 Version 1.03 has been added to the Perl core.
844 Version 2.4 has been added to the Perl core.
846 =item C<XS::APItest::KeywordRPN>
848 Version 0.003 has been added to the Perl core.
852 =head2 Updated Pragmata
858 Upgraded from version 2.13 to 2.15.
862 Upgraded from version 0.22 to 0.23.
866 C<charnames> now contains the Unicode F<NameAliases.txt> database file.
867 This has the effect of adding some extra C<\N> character names that
868 formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
871 Upgraded from version 1.06 to 1.07.
875 Upgraded from version 1.13 to 1.20.
879 C<diagnostics> now supports %.0f formatting internally.
881 C<diagnostics> no longer suppresses C<Use of uninitialized value in range
882 (or flip)> warnings. [perl #71204]
884 Upgraded from version 1.17 to 1.19.
888 In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
889 bundles has changed slightly. The last component, if any (i.e. C<X>) is
890 simply ignored. This is predicated on the assumption that new features
891 will not, in general, be added to maintenance releases. So C<:5.10>
892 and C<:5.10.X> have identical effect. This is a change to the behaviour
893 documented for 5.10.0.
895 C<feature> now includes the C<unicode_strings> feature:
897 use feature "unicode_strings";
899 This pragma turns on Unicode semantics for the case-changing operations
900 (C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
901 internal UTF-8 flag set, but that contain single-byte characters between
904 Upgraded from version 1.11 to 1.16.
908 C<less> now includes the C<stash_name> method to allow subclasses of
909 C<less> to pick where in %^H to store their stash.
911 Upgraded from version 0.02 to 0.03.
915 Upgraded from version 0.5565 to 0.62.
919 C<mro> is now implemented as an XS extension. The documented interface has
920 not changed. Code relying on the implementation detail that some C<mro::>
921 methods happened to be available at all times gets to "keep both pieces".
923 Upgraded from version 1.00 to 1.02.
927 C<overload> now allow overloading of 'qr'.
929 Upgraded from version 1.06 to 1.10.
933 Upgraded from version 1.67 to 1.75.
935 =item C<threads::shared>
937 Upgraded from version 1.14 to 1.32.
941 C<version> now has support for L</Version number formats> as described
942 earlier in this document and in its own documentation.
944 Upgraded from version 0.74 to 0.82.
948 C<warnings> has a new C<warnings::fatal_enabled()> function. It also
949 includes a new C<illegalproto> warning category. See also L</New or
950 Changed Diagnostics> for this change.
952 Upgraded from version 1.06 to 1.09.
956 =head2 Updated Modules
960 =item C<Archive::Extract>
962 Upgraded from version 0.24 to 0.38.
964 =item C<Archive::Tar>
966 Upgraded from version 1.38 to 1.54.
968 =item C<Attribute::Handlers>
970 Upgraded from version 0.79 to 0.87.
974 Upgraded from version 5.63 to 5.70.
978 Upgraded from version 0.74 to 0.78.
982 Upgraded from version 1.05 to 1.12.
986 Upgraded from version 0.83 to 0.96.
990 Upgraded from version 1.09 to 1.11_01.
994 Upgraded from version 3.29 to 3.48.
998 Upgraded from version 0.33 to 0.36.
1000 NOTE: C<Class::ISA> is deprecated and may be removed from a future
1003 =item C<Compress::Raw::Zlib>
1005 Upgraded from version 2.008 to 2.024.
1009 Upgraded from version 1.9205 to 1.94_56.
1013 Upgraded from version 0.84 to 0.90.
1015 =item C<CPANPLUS::Dist::Build>
1017 Upgraded from version 0.06_02 to 0.46.
1019 =item C<Data::Dumper>
1021 Upgraded from version 2.121_14 to 2.125.
1025 Upgraded from version 1.816_1 to 1.820.
1027 =item C<Devel::PPPort>
1029 Upgraded from version 3.13 to 3.19.
1033 Upgraded from version 1.15 to 1.16.
1035 =item C<Digest::MD5>
1037 Upgraded from version 2.36_01 to 2.39.
1039 =item C<Digest::SHA>
1041 Upgraded from version 5.45 to 5.47.
1045 Upgraded from version 2.23 to 2.39.
1049 Upgraded from version 5.62 to 5.64_01.
1051 =item C<ExtUtils::CBuilder>
1053 Upgraded from version 0.21 to 0.27.
1055 =item C<ExtUtils::Command>
1057 Upgraded from version 1.13 to 1.16.
1059 =item C<ExtUtils::Constant>
1061 Upgraded from version 0.2 to 0.22.
1063 =item C<ExtUtils::Install>
1065 Upgraded from version 1.44 to 1.55.
1067 =item C<ExtUtils::MakeMaker>
1069 Upgraded from version 6.42 to 6.56.
1071 =item C<ExtUtils::Manifest>
1073 Upgraded from version 1.51_01 to 1.57.
1075 =item C<ExtUtils::ParseXS>
1077 Upgraded from version 2.18_02 to 2.21.
1079 =item C<File::Fetch>
1081 Upgraded from version 0.14 to 0.24.
1085 Upgraded from version 2.04 to 2.08_01.
1089 Upgraded from version 0.18 to 0.22.
1091 =item C<Filter::Simple>
1093 Upgraded from version 0.82 to 0.84.
1095 =item C<Filter::Util::Call>
1097 Upgraded from version 1.07 to 1.08.
1099 =item C<Getopt::Long>
1101 Upgraded from version 2.37 to 2.38.
1105 Upgraded from version 1.23_01 to 1.25_02.
1109 Upgraded from version 1.07 to 1.10.
1113 Upgraded from version 0.40_1 to 0.54.
1117 Upgraded from version 1.05 to 2.01.
1119 =item C<Locale::Maketext>
1121 Upgraded from version 1.12 to 1.14.
1123 =item C<Locale::Maketext::Simple>
1125 Upgraded from version 0.18 to 0.21.
1127 =item C<Log::Message>
1129 Upgraded from version 0.01 to 0.02.
1131 =item C<Log::Message::Simple>
1133 Upgraded from version 0.04 to 0.06.
1135 =item C<Math::BigInt>
1137 Upgraded from version 1.88 to 1.89_01.
1139 =item C<Math::BigInt::FastCalc>
1141 Upgraded from version 0.16 to 0.19.
1143 =item C<Math::BigRat>
1145 Upgraded from version 0.21 to 0.24.
1147 =item C<Math::Complex>
1149 Upgraded from version 1.37 to 1.56.
1153 Upgraded from version 1.01_02 to 1.01_03.
1155 =item C<MIME::Base64>
1157 Upgraded from version 3.07_01 to 3.08.
1159 =item C<Module::Build>
1161 Upgraded from version 0.2808_01 to 0.3603.
1163 =item C<Module::CoreList>
1165 Upgraded from version 2.12 to 2.29.
1167 =item C<Module::Load>
1169 Upgraded from version 0.12 to 0.16.
1171 =item C<Module::Load::Conditional>
1173 Upgraded from version 0.22 to 0.34.
1175 =item C<Module::Loaded>
1177 Upgraded from version 0.01 to 0.06.
1179 =item C<Module::Pluggable>
1181 Upgraded from version 3.6 to 3.9.
1185 Upgraded from version 2.33 to 2.36.
1189 Upgraded from version 0.60_01 to 0.64.
1191 =item C<Object::Accessor>
1193 Upgraded from version 0.32 to 0.36.
1195 =item C<Package::Constants>
1197 Upgraded from version 0.01 to 0.02.
1201 Upgraded from version 1.04 to 1.06.
1203 =item C<Pod::Parser>
1205 Upgraded from version 1.35 to 1.37.
1207 =item C<Pod::Perldoc>
1209 Upgraded from version 3.14_02 to 3.15_02.
1211 =item C<Pod::Plainer>
1213 Upgraded from version 0.01 to 1.02.
1215 NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
1218 =item C<Pod::Simple>
1220 Upgraded from version 3.05 to 3.13.
1224 Upgraded from version 2.12 to 2.22.
1228 Upgraded from version 1.11 to 1.17.
1232 Upgraded from version 2.18 to 2.22.
1236 Upgraded from version 2.13 to 2.16.
1238 NOTE: C<Switch> is deprecated and may be removed from a future version
1241 =item C<Sys::Syslog>
1243 Upgraded from version 0.22 to 0.27.
1245 =item C<Term::ANSIColor>
1247 Upgraded from version 1.12 to 2.02.
1251 Upgraded from version 0.18 to 0.20.
1255 Upgraded from version 1.25 to 1.25_02.
1257 =item C<Test::Harness>
1259 Upgraded from version 2.64 to 3.17.
1261 =item C<Test::Simple>
1263 Upgraded from version 0.72 to 0.94.
1265 =item C<Text::Balanced>
1267 Upgraded from version 2.0.0 to 2.02.
1269 =item C<Text::ParseWords>
1271 Upgraded from version 3.26 to 3.27.
1273 =item C<Text::Soundex>
1275 Upgraded from version 3.03 to 3.03_01.
1277 =item C<Thread::Queue>
1279 Upgraded from version 2.00 to 2.11.
1281 =item C<Thread::Semaphore>
1283 Upgraded from version 2.01 to 2.09.
1285 =item C<Tie::RefHash>
1287 Upgraded from version 1.37 to 1.38.
1289 =item C<Time::HiRes>
1291 Upgraded from version 1.9711 to 1.9719.
1293 =item C<Time::Local>
1295 Upgraded from version 1.18 to 1.1901_01.
1297 =item C<Time::Piece>
1299 Upgraded from version 1.12 to 1.15.
1301 =item C<Unicode::Collate>
1303 Upgraded from version 0.52 to 0.52_01.
1305 =item C<Unicode::Normalize>
1307 Upgraded from version 1.02 to 1.03.
1311 Upgraded from version 0.34 to 0.39.
1313 =item C<Win32API::File>
1315 Upgraded from version 0.1001_01 to 0.1101.
1319 Upgraded from version 0.08 to 0.10.
1323 =head2 Removed Modules and Pragmata
1329 Removed from the Perl core. Prior version was 1.02.
1331 =item C<CPAN::API::HOWTO>
1333 Removed from the Perl core. Prior version was 'undef'.
1335 =item C<CPAN::DeferedCode>
1337 Removed from the Perl core. Prior version was 5.50.
1339 =item C<CPANPLUS::inc>
1341 Removed from the Perl core. Prior version was 'undef'.
1345 Removed from the Perl core. Prior version was 1.03.
1347 =item C<ExtUtils::MakeMaker::bytes>
1349 Removed from the Perl core. Prior version was 6.42.
1351 =item C<ExtUtils::MakeMaker::vmsish>
1353 Removed from the Perl core. Prior version was 6.42.
1357 Removed from the Perl core. Prior version was 2.3.
1359 =item C<Test::Harness::Assert>
1361 Removed from the Perl core. Prior version was 0.02.
1363 =item C<Test::Harness::Iterator>
1365 Removed from the Perl core. Prior version was 0.02.
1367 =item C<Test::Harness::Point>
1369 Removed from the Perl core. Prior version was 0.01.
1371 =item C<Test::Harness::Results>
1373 Removed from the Perl core. Prior version was 0.01.
1375 =item C<Test::Harness::Straps>
1377 Removed from the Perl core. Prior version was 0.26_01.
1379 =item C<Test::Harness::Util>
1381 Removed from the Perl core. Prior version was 0.01.
1385 Removed from the Perl core. Prior version was 1.1.
1389 =head2 Deprecated Modules and Pragmata
1391 See L</Deprecated Modules> above.
1394 =head1 Documentation
1396 =head2 New Documentation
1402 L<perlhaiku> contains instructions on how to build perl for the Haiku
1407 L<perlmroapi> describes the new interface for pluggable Method Resolution
1412 L<perlperf>, by Richard Foley, provides an introduction to the use of
1413 performance and optimization techniques which can be used with particular
1414 reference to perl programs.
1418 L<perlrepository> describes how to access the perl source using the I<git>
1419 version control system.
1423 L<perlpolicy> extends the "Social contract about contributed modules" into
1424 the beginnings of a document on Perl porting policies.
1428 =head2 Changes to Existing Documentation
1435 The various large F<Changes*> files (which listed every change made
1436 to perl over the last 18 years) have been removed, and replaced by a
1437 small file, also called F<Changes>, which just explains how that same
1438 information may be extracted from the git version control system.
1442 F<Porting/patching.pod> has been deleted, as it mainly described
1443 interacting with the old Perforce-based repository, which is now obsolete.
1444 Information still relevant has been moved to L<perlrepository>.
1448 The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
1449 as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
1450 BLOCK>, although actually using the latter may not be the best idea for
1451 the readability of your source code.
1455 Documented -X overloading.
1459 Documented that C<when()> treats specially most of the filetest operators
1463 Documented C<when> as a syntax modifier.
1467 Eliminated "Old Perl threads tutorial", which described 5005 threads.
1469 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1473 Correct previous documentation: v-strings are not deprecated
1475 With version objects, we need them to use MODULE VERSION syntax. This
1476 patch removes the deprecation notice.
1480 Security contact information is now part of L<perlsec>.
1484 A significant fraction of the core documentation has been updated to
1485 clarify the behavior of Perl's Unicode handling.
1487 Much of the remaining core documentation has been reviewed and edited
1488 for clarity, consistent use of language, and to fix the spelling of Tom
1489 Christiansen's name.
1493 The Pod specification (L<perlpodspec>) has been updated to bring the
1494 specification in line with modern usage already supported by most Pod
1495 systems. A parameter string may now follow the format name in a
1496 "begin/end" region. Links to URIs with a text description are now
1497 allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
1502 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1503 conditional loading of modules despite the implicit BEGIN block around
1508 The documentation for C<$1> in perlvar.pod has been clarified.
1512 C<\N{U+I<code point>}> is now documented.
1516 =head1 Selected Performance Enhancements
1522 A new internal cache means that C<isa()> will often be faster.
1526 The implementation of C<C3> Method Resolution Order has been
1527 optimised - linearisation for classes with single inheritance is 40%
1528 faster. Performance for multiple inheritance is unchanged.
1532 Under C<use locale>, the locale-relevant information is now cached on
1533 read-only values, such as the list returned by C<keys %hash>. This makes
1534 operations such as C<sort keys %hash> in the scope of C<use locale>
1539 Empty C<DESTROY> methods are no longer called.
1543 C<Perl_sv_utf8_upgrade()> is now faster.
1547 C<keys> on empty hash is now faster.
1551 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
1555 The string repetition operator (C<$str x $num>) is now several times
1556 faster when C<$str> has length one or C<$num> is large.
1560 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1561 now happens in-place and is several orders of magnitude faster than
1562 it used to be. It will also preserve non-existent elements whenever
1563 possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
1564 and C<DELETE> methods.
1568 =head1 Installation and Configuration Improvements
1574 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
1575 generated at build time, rather than being shipped as part of the release.
1579 If C<vendorlib> and C<vendorarch> are the same, then they are only added
1584 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1585 perl is built with C<-Dusedevel>.
1589 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1590 against stack-smashing attacks, if the compiler supports it.
1594 F<Configure> will now determine the correct prototypes for re-entrant
1595 functions and for C<gconvert> if you are using a C++ compiler rather
1600 On Unix, if you build from a tree containing a git repository, the
1601 configuration process will note the commit hash you have checked out, for
1602 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1603 are automatically added to the list of local patches displayed by
1608 Perl now supports SystemTap's C<dtrace> compatibility layer and an
1609 issue with linking C<miniperl> has been fixed in the process.
1613 perldoc now uses C<less -R> instead of C<less> for improved behaviour
1614 in the face of C<groff>'s new usage of ANSI escape codes.
1619 C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
1620 C<USE_ATTRIBUTES_FOR_PERLIO>.
1624 As part of the flattening of F<ext>, all extensions on all platforms are
1625 built by F<make_ext.pl>. This replaces the Unix-specific
1626 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1627 F<win32/buildext.pl>.
1631 =head1 Internal Changes
1633 Each release of Perl sees numerous internal changes which shouldn't
1634 affect day to day usage but may still be notable for developers working
1635 with Perl's source code.
1641 The J.R.R. Tolkien quotes at the head of C source file have been checked
1642 and proper citations added, thanks to a patch from Tom Christiansen.
1646 The internal structure of the dual-life modules traditionally found in
1647 the F<lib/> and F<ext/> directories in the perl source has changed
1648 significantly. Where possible, dual-lifed modules have been extracted
1649 from F<lib/> and F<ext/>.
1651 Dual-lifed modules maintained by Perl's developers as part of the Perl
1652 core now live in F<dist/>. Dual-lifed modules maintained primarily on
1653 CPAN now live in F<cpan/>. When reporting a bug in a module located
1654 under F<cpan/>, please send your bug report directly to the module's
1655 bug tracker or author, rather than Perl's bug tracker.
1659 C<\N{...}> now compiles better, always forces UTF-8 internal representation
1661 Perl's developers have fixed several problems with the recognition of
1662 C<\N{...}> constructs. As part of this, perl will store any scalar
1663 or regex containing C<\N{I<name>}> or C<\N{U+I<code point>}> in its
1664 definition in UTF-8 format. (This was true previously for all occurrences
1665 of C<\N{I<name>}> that did not use a custom translator, but now it's
1670 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1674 C<SVt_RV> no longer exists. RVs are now stored in IVs.
1678 C<Perl_vcroak()> now accepts a null first argument. In addition, a full
1679 audit was made of the "not NULL" compiler annotations, and those for
1680 several other internal functions were corrected.
1684 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1685 have been added to formalise the temporary saving of the C<errno>
1690 The function C<Perl_sv_insert_flags> has been added to augment
1695 The function C<Perl_newSV_type(type)> has been added, equivalent to
1696 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1700 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1701 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1703 Two flag bits are currently supported.
1709 C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
1710 not convert a sequence of ISO 8859-1 characters to UTF-8). A wrapper,
1711 C<newSVpvn_utf8()> is available for this.
1715 C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
1719 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1723 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1728 Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
1732 C<PL_na> has been exterminated from the core code, replaced by local
1733 STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
1734 C<PL_na>, which is a pointer dereference into the interpreter structure
1735 under ithreads, and a global variable otherwise.
1739 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
1740 on the scalar. It now updates the linked list to remove each piece of
1741 magic as it is freed.
1745 Under ithreads, the regex in C<PL_reg_curpm> is now reference
1746 counted. This eliminates a lot of hackish workarounds to cope with it
1747 not being reference counted.
1751 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1752 This has been fixed.
1756 The I<public> IV and NV flags are now not set if the string value has
1757 trailing "garbage". This behaviour is consistent with not setting the
1758 public IV or NV flags if the value is out of range for the type.
1762 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
1763 been replaced by C<NULL> in the core code, and non-dual-life modules,
1764 as C<NULL> is clearer to those unfamiliar with the core code.
1768 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1769 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1770 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1771 casting away C<const>. This allows proper compile-time auditing of
1772 C<const> correctness in the core, and helped picked up some errors
1777 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1778 stack and mortalizing them.
1782 Use of the private structure C<mro_meta> has changed slightly. Nothing
1783 outside the core should be accessing this directly anyway.
1787 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1788 to view how a C preprocessor macro would be expanded when compiled.
1789 This is handy when trying to decode the macro hell that is the perl
1796 =head2 Testing improvements
1800 =item Parallel tests
1802 The core distribution can now run its regression tests in parallel on
1803 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
1804 your environment to the number of tests to run in parallel, and run
1805 C<make test_harness>. On a Bourne-like shell, this can be done as
1807 TEST_JOBS=3 make test_harness # Run 3 tests in parallel
1809 An environment variable is used, rather than parallel make itself, because
1810 L<TAP::Harness> needs to be able to schedule individual non-conflicting test
1811 scripts itself, and there is no standard interface to C<make> utilities to
1812 interact with their job schedulers.
1814 Note that currently some test scripts may fail when run in parallel (most
1815 notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
1816 again sequentially and see if the failures go away.
1818 =item Test harness flexibility
1820 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1824 Several tests that have the potential to hang forever if they fail now
1825 incorporate a "watchdog" functionality that will kill them after a timeout,
1826 which helps ensure that C<make test> and C<make test_harness> run to
1827 completion automatically.
1834 Perl's developers have added a number of new tests to the core.
1835 In addition to the items listed below, many modules updated from CPAN
1836 incorporate new tests.
1842 Significant cleanups to core tests to ensure that language and
1843 interpreter features are not used before they're tested.
1847 C<make test_porting> now runs a number of important pre-commit checks
1848 which might be of use to anyone working on the Perl core.
1852 F<t/porting/podcheck.t> automatically checks the well-formedness of
1853 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1854 dual-lifed modules which are primarily maintained outside the Perl core.
1858 F<t/porting/manifest.t> now tests that all files listed in MANIFEST
1863 F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
1867 F<t/comp/retainedlines.t> checks that the debugger can retain source
1872 F<t/io/perlio_fail.t> checks that bad layers fail.
1876 F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
1880 F<t/io/perlio_open.t> checks that certain special forms of open work.
1884 F<t/io/perlio.t> includes general PerlIO tests.
1888 F<t/io/pvbm.t> checks that there is no unexpected interaction between
1889 the internal types C<PVBM> and C<PVGV>.
1893 F<t/mro/package_aliases.t> checks that mro works properly in the presence
1894 of aliased packages.
1898 F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
1902 F<t/op/index_thr.t> tests the interaction of C<index> and threads.
1906 F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
1910 F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
1914 F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
1918 F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
1919 embedded C<qr//> and threads.
1923 F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
1928 F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
1929 properties and threads.
1933 F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
1937 F<t/op/reg_posixcc.t> checks that POSIX character classes behave
1942 F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
1946 F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
1950 F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
1954 F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
1958 F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
1962 F<t/uni/tie.t> checks that Unicode and C<tie> work.
1966 F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
1970 F<t/comp/form_scope.t> tests format scoping.
1974 F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
1978 F<t/op/filetest_t.t> tests if -t file test works.
1982 F<t/op/qr.t> tests C<qr>.
1986 F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
1990 F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
1994 F<t/op/filehandle.t> tests some suitably portable filetest operators
1995 to check that they work as expected, particularly in the light of some
1996 internal changes made in how filehandles are blessed.
2000 F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
2001 can now be handed to C<gmtime> and C<localtime>, do not cause an internal
2002 overflow or an excessively long loop.
2007 =head1 New or Changed Diagnostics
2009 =head2 New Diagnostics
2015 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
2016 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
2017 that was enabled when the F<perl> binary was compiled.
2021 Smartmatch resolution tracing has been added as a new diagnostic. Use
2022 C<-DM> to enable it.
2026 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
2027 C<-Dx> for its original purpose of dumping syntax trees.
2031 Perl 5.12 provides a number of new diagnostic messages to help you write
2032 better code. See L<perldiag> for details of these new messages.
2038 C<Bad plugin affecting keyword '%s'>
2042 C<gmtime(%.0f) too large>
2046 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
2050 C<Lexing code internal error (%s)>
2054 C<localtime(%.0f) too large>
2058 C<Overloaded dereference did not return a reference>
2062 C<Overloaded qr did not return a REGEXP>
2066 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
2070 C<lvalue attribute ignored after the subroutine has been defined>
2072 This new warning is issued when one attempts to mark a subroutine as
2073 lvalue after it has been defined.
2077 Perl now warns you if C<++> or C<--> are unable to change the value
2078 because it's beyond the limit of representation.
2080 This uses a new warnings category: "imprecision".
2084 C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
2088 C<Show constant in "Useless use of a constant in void context">
2092 C<Prototype after '%s'>
2096 C<panic: sv_chop %s>
2098 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
2099 passed a position that is not within the scalar's string buffer. This
2100 could be caused by buggy XS code, and at this point recovery is not
2105 The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
2106 C<charnames> handler returns malformed UTF-8.
2110 If an unresolved named character or sequence was encountered when
2111 compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
2112 by the lexer> is now produced. This can happen, for example, when using a
2113 single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
2114 for more examples of how the lexer can get bypassed.
2118 C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
2119 triggered when the character constant represented by C<...> is not a
2120 valid hexadecimal number.
2124 The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
2125 class, just like C<.> in a character class loses its special meaning,
2126 and will cause the fatal error C<\N in a character class must be a named
2127 character: \N{...}>.
2131 The rules on what is legal for the C<...> in C<\N{...}> have been
2132 tightened up so that unless the C<...> begins with an alphabetic
2133 character and continues with a combination of alphanumerics, dashes,
2134 spaces, parentheses or colons then the warning C<Deprecated character(s)
2135 in \N{...} starting at '%s'> is now issued.
2139 The warning C<Using just the first characters returned by \N{}> will
2140 be issued if the C<charnames> handler returns a sequence of characters
2141 which exceeds the limit of the number of characters that can be used. The
2142 message will indicate which characters were used and which were discarded.
2148 =head2 Changed Diagnostics
2150 A number of existing diagnostic messages have been improved or corrected:
2156 A new warning category C<illegalproto> allows finer-grained control of
2157 warnings around function prototypes.
2163 =item C<Illegal character in prototype for %s : %s>
2165 =item C<Prototype after '%c' for %s : %s>
2169 have been moved from the C<syntax> top-level warnings category into a new
2170 first-level category, C<illegalproto>. These two warnings are currently
2171 the only ones emitted during parsing of an invalid/illegal prototype,
2174 no warnings 'illegalproto';
2176 to suppress only those, but not other syntax-related warnings. Warnings
2177 where prototypes are changed, ignored, or not met are still in the
2178 C<prototype> category as before.
2182 C<Deep recursion on subroutine "%s">
2184 It is now possible to change the depth threshold for this warning from the
2185 default of 100, by recompiling the F<perl> binary, setting the C
2186 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
2190 C<Illegal character in prototype> warning is now more precise
2191 when reporting illegal characters after _
2195 mro merging error messages are now very similar to those produced by
2200 Amelioration of the error message "Unrecognized character %s in column %d"
2202 Changes the error message to "Unrecognized character %s; marked by E<lt>--
2203 HERE after %sE<lt>-- HERE near column %d". This should make it a little
2204 simpler to spot and correct the suspicious character.
2208 Perl now explicitly points to C<$.> when it causes an uninitialized
2209 warning for ranges in scalar context.
2213 C<split> now warns when called in void context.
2217 C<printf>-style functions called with too few arguments will now issue the
2218 warning C<"Missing argument in %s"> [perl #71000]
2222 Perl now properly returns a syntax error instead of segfaulting
2223 if C<each>, C<keys>, or C<values> is used without an argument.
2227 C<tell()> now fails properly if called without an argument and when no
2228 previous file was read.
2230 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
2231 the 5.8.x behaviour.
2235 C<overload> no longer implicitly unsets fallback on repeated 'use
2240 POSIX::strftime() can now handle Unicode characters in the format string.
2244 The C<syntax> category was removed from 5 warnings that should only be in
2249 Three fatal C<pack>/C<unpack> error messages have been normalized to
2254 C<Unicode character is illegal> has been rephrased to be more accurate
2256 It now reads C<Unicode non-character is illegal in interchange> and the
2257 perldiag documentation has been expanded a bit.
2261 Currently, all but the first of the several characters that the
2262 C<charnames> handler may return are discarded when used in a regular
2263 expression pattern bracketed character class. If this happens then the
2264 warning C<Using just the first character returned by \N{} in character
2265 class> will be issued.
2269 The warning C<Missing right brace on \N{} or unescaped left brace after
2270 \N. Assuming the latter> will be issued if Perl encounters a C<\N{>
2271 but doesn't find a matching C<}>. In this case Perl doesn't know if it
2272 was mistakenly omitted, or if "match non-newline" followed by "match
2273 a C<{>" was desired. It assumes the latter because that is actually a
2274 valid interpretation as written, unlike the other case. If you meant
2275 the former, you need to add the matching right brace. If you did mean
2276 the latter, you can silence this warning by writing instead C<\N\{>.
2280 C<gmtime> and C<localtime> called with numbers smaller than they can
2281 reliably handle will now issue the warnings C<gmtime(%.0f) too small>
2282 and C<localtime(%.0f) too small>.
2286 The following diagnostic messages have been removed:
2296 C<Can't locate package %s for the parents of %s>
2298 In general this warning it only got produced in
2299 conjunction with other warnings, and removing it allowed an ISA lookup
2300 optimisation to be added.
2304 C<v-string in use/require is non-portable>
2308 =head1 Utility Changes
2314 F<h2ph> now looks in C<include-fixed> too, which is a recent addition
2315 to gcc's search path.
2319 F<h2xs> no longer incorrectly treats enum values like macros.
2320 It also now handles C++ style comments (C<//>) properly in enums.
2324 F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
2325 debugger now correctly handles proxy constant subroutines, and
2330 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
2331 upstream bug tracker URLs. If a user identifies a particular module
2332 as the topic of their bug report and we're able to divine the URL for
2333 its upstream bug tracker, perlbug now provide a message to the user
2334 explaining that the core copies the CPAN version directly, and provide
2335 the URL for reporting the bug directly to the upstream author.
2337 F<perlbug> no longer reports "Message sent" when it hasn't actually sent
2342 F<perlthanks> is a new utility for sending non-bug-reports to the
2343 authors and maintainers of Perl. Getting nothing but bug reports can
2344 become a bit demoralising. If Perl 5.12 works well for you, please try
2345 out F<perlthanks>. It will make the developers smile.
2349 Perl's developers have fixed bugs in F<a2p> having to do with the
2350 C<match()> operator in list context. Additionally, F<a2p> no longer
2351 generates code that uses the C<$[> variable.
2355 =head1 Selected Bug Fixes
2361 U+0FFFF is now a legal character in regular expressions.
2365 pp_qr now always returns a new regexp SV. Resolves RT #69852.
2367 Instead of returning a(nother) reference to the (pre-compiled) regexp
2368 in the optree, use reg_temp_copy() to create a copy of it, and return a
2369 reference to that. This resolves issues about Regexp::DESTROY not being
2370 called in a timely fashion (the original bug tracked by RT #69852), as
2371 well as bugs related to blessing regexps, and of assigning to regexps,
2372 as described in correspondence added to the ticket.
2374 It transpires that we also need to undo the SvPVX() sharing when ithreads
2375 cloning a Regexp SV, because mother_re is set to NULL, instead of a
2376 cloned copy of the mother_re. This change might fix bugs with regexps
2377 and threads in certain other situations, but as yet neither tests nor
2378 bug reports have indicated any problems, so it might not actually be an
2379 edge case that it's possible to reach.
2383 Several compilation errors and segfaults when perl was built with C<-Dmad>
2388 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
2392 C<-t> should only return TRUE for file handles connected to a TTY
2394 The Microsoft C version of C<isatty()> returns TRUE for all character mode
2395 devices, including the F</dev/null>-style "nul" device and printers like
2400 Fixed a regression caused by commit fafafbaf which caused a panic during
2401 parameter passing [perl #70171]
2405 On systems which in-place edits without backup files, -i'*' now works as
2406 the documentation says it does [perl #70802]
2410 Saving and restoring magic flags no longer loses readonly flag.
2414 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
2415 causes abrupt and total failure.
2419 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
2424 Using named subroutines with C<sort> should no longer lead to bus errors
2429 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
2433 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
2437 C<$@> may now be assigned a read-only value (without error or busting
2442 C<sort> called recursively from within an active comparison subroutine no
2443 longer causes a bus error if run multiple times. [perl #71076]
2447 Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
2451 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
2456 C<-I> on shebang line now adds directories in front of @INC
2457 as documented, and as does C<-I> when specified on the command-line.
2461 C<kill> is now fatal when called on non-numeric process identifiers.
2462 Previously, an C<undef> process identifier would be interpreted as a
2463 request to kill process 0, which would terminate the current process
2464 group on POSIX systems. Since process identifiers are always integers,
2465 killing a non-numeric process is now fatal.
2469 5.10.0 inadvertently disabled an optimisation, which caused a measurable
2470 performance drop in list assignment, such as is often used to assign
2471 function parameters from C<@_>. The optimisation has been re-instated, and
2472 the performance regression fixed. (This fix is also present in 5.10.1)
2476 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
2480 Some potential coredumps in PerlIO fixed [RT #57322,54828].
2484 The debugger now works with lvalue subroutines.
2488 The debugger's C<m> command was broken on modules that defined constants
2493 C<crypt> and string complement could return tainted values for untainted
2494 arguments [RT #59998].
2498 The C<-i>I<.suffix> command-line switch now recreates the file using
2499 restricted permissions, before changing its mode to match the original
2500 file. This eliminates a potential race condition [RT #60904].
2504 On some Unix systems, the value in C<$?> would not have the top bit set
2505 (C<$? & 128>) even if the child core dumped.
2509 Under some circumstances, C<$^R> could incorrectly become undefined
2514 In the XS API, various hash functions, when passed a pre-computed hash where
2515 the key is UTF-8, might result in an incorrect lookup.
2519 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2524 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
2525 didn't exist, even if the object's C<@ISA> contained C<Foo>.
2529 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2530 C<@ISA>, have been found and fixed.
2534 Bitwise operations on references could crash the interpreter, e.g.
2535 C<$x=\$y; $x |= "foo"> [RT #54956].
2539 Patterns including alternation might be sensitive to the internal UTF-8
2540 representation, e.g.
2542 my $byte = chr(192);
2543 my $utf8 = chr(192); utf8::upgrade($utf8);
2544 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2548 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2549 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2550 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2551 greater than 255 [RT #59908].
2555 C<B::Deparse> failed to correctly deparse various constructs:
2556 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2557 C<sub foo(_)> [RT #62484].
2561 Using C<setpgrp> with no arguments could corrupt the perl stack.
2565 The block form of C<eval> is now specifically trappable by C<Safe> and
2566 C<ops>. Previously it was erroneously treated like string C<eval>.
2570 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2571 match operator (C<~~>) [RT #63854].
2575 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2576 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2578 ("ab" x 32768) =~ /^(ab)*$/
2582 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2586 Using C<next> or C<last> to exit a C<given> block no longer produces a
2587 spurious warning like the following:
2589 Exiting given via last at foo.pl line 123
2593 Assigning a format to a glob could corrupt the format; e.g.:
2595 *bar=*foo{FORMAT}; # foo format now bad
2599 Attempting to coerce a typeglob to a string or number could cause an
2600 assertion failure. The correct error message is now generated,
2601 C<Can't coerce GLOB to I<$type>>.
2605 Under C<use filetest 'access'>, C<-x> was using the wrong access
2606 mode. This has been fixed [RT #49003].
2610 C<length> on a tied scalar that returned a Unicode value would not be
2611 correct the first time. This has been fixed.
2615 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2620 A race condition inside C<PerlIOStdio_close()> has been identified and
2621 fixed. This used to cause various threading issues, including SEGVs.
2625 In C<unpack>, the use of C<()> groups in scalar context was internally
2626 placing a list on the interpreter's stack, which manifested in various
2627 ways, including SEGVs. This is now fixed [RT #50256].
2631 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2632 These have all been fixed.
2636 A 5.10.0 optimisation to clear the temporary stack within the implicit
2637 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2638 obscure bugs in seemingly unrelated parts of the interpreter [commit
2643 The line numbers for warnings inside C<elsif> are now correct.
2647 The C<..> operator now works correctly with ranges whose ends are at or
2648 close to the values of the smallest and largest integers.
2652 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2653 This has been fixed [RT #54828].
2657 An off-by-one error meant that C<index $str, ...> was effectively being
2658 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2662 Various leaks associated with named captures in regexes have been fixed
2667 A weak reference to a hash would leak. This was affecting C<DBI>
2672 Using (?|) in a regex could cause a segfault [RT #59734].
2676 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2680 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2681 unaligned 64-bit access on the SPARC architecture [RT #60574].
2685 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2686 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2691 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2696 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2697 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2702 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2703 missed (method cache issue) [RT #60220,60232].
2707 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2708 cause a memory leak [RT #63110].
2712 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2713 specified on the command line. C<-C> on the shebang line used to be a
2714 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2715 disallowed it, which broke some scripts. Now perl checks whether it is
2716 also on the command line and only dies if it is not [RT #67880].
2720 In 5.10.0, certain types of re-entrant regular expression could crash,
2721 or cause the following assertion failure [RT #60508]:
2723 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2727 Perl now includes previously missing files from the Unicode Character
2732 Perl now honors C<TMPDIR> when opening an anonymous temporary file.
2737 =head1 Platform Specific Changes
2739 Perl is incredibly portable. In general, if a platform has a C compiler,
2740 someone has ported Perl to it (or will soon). We're happy to announce
2741 that Perl 5.12 includes support for several new platforms. At the same
2742 time, it's time to bid farewell to some (very) old friends.
2744 =head2 New Platforms
2750 Perl's developers have merged patches from Haiku's maintainers. Perl
2751 should now build on Haiku.
2755 Perl should now build on MirOS BSD.
2759 =head2 Discontinued Platforms
2771 =head2 Updated Platforms
2781 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
2786 Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
2787 installed. The F<libgdbm> is delivered as an optional package with the
2788 AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
2792 Hints changes mean that AIX 4.2 should work again.
2802 Perl now supports IPv6 on Cygwin 1.7 and newer.
2806 On Cygwin we now strip the last number from the DLL. This has been the
2807 behaviour in the cygwin.com build for years. The hints files have been
2812 =item Darwin (Mac OS X)
2818 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2819 as it's still buggy.
2823 Correct infelicities in the regexp used to identify buggy locales
2824 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2834 Fix thread library selection [perl #69686]
2844 The hints files now identify the correct threading libraries on FreeBSD 7
2855 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2856 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2866 Hints now supports versions 5.*.
2876 C<-UDEBUGGING> is now the default on VMS.
2878 Like it has been everywhere else for ages and ages. Also make command-line
2879 selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
2880 the only way to turn it off was by saying no in answer to the interactive
2885 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2890 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2891 if C<$/> was set to a numeric reference (to indicate record-style reads).
2896 VMS now supports C<getgrgid>.
2900 Many improvements and cleanups have been made to the VMS file name handling
2901 and conversion code.
2905 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2906 status in a VMS condition value for better interaction with GNV's bash
2907 shell and other utilities that depend on POSIX exit values. See
2908 L<perlvms/"$?"> for details.
2912 C<File::Copy> now detects Unix compatibility mode on VMS.
2922 Various changes from Stratus have been merged in.
2932 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2942 Perl 5.12 supports Windows 2000 and later. The supporting code for
2943 legacy versions of Windows is still included, but will be removed
2944 during the next development cycle.
2948 Initial support for building Perl with MinGW-w64 is now available.
2952 F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
2953 settings for Windows Vista and later. Without this setting Windows
2954 would treat F<perl.exe> as a legacy application and apply various
2955 heuristics like redirecting access to protected file system areas
2956 (like the "Program Files" folder) to the users "VirtualStore"
2957 instead of generating a proper "permission denied" error.
2959 The manifest resource also requests the Microsoft Common-Controls
2960 version 6.0 (themed controls introduced in Windows XP). Check out the
2961 Win32::VisualStyles module on CPAN to switch back to old style
2962 unthemed controls for legacy applications.
2966 The C<-t> filetest operator now only returns true if the filehandle
2967 is connected to a console window. In previous versions of Perl it
2968 would return true for all character mode devices, including F<NUL>
2973 The C<-p> filetest operator now works correctly, and the
2974 Fcntl::S_IFIFO constant is defined when Perl is compiled with
2975 Microsoft Visual C. In previous Perl versions C<-p> always
2976 returned a false value, and the Fcntl::S_IFIFO constant
2979 This bug is specific to Microsoft Visual C and never affected
2980 Perl binaries built with MinGW.
2984 The socket error codes are now more widely supported: The POSIX
2985 module will define the symbolic names, like POSIX::EWOULDBLOCK,
2986 and stringification of socket error codes in $! works as well
2989 C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
2990 A non-blocking socket operation could not be completed immediately.
2994 flock() will now set sensible error codes in $!. Previous Perl versions
2995 copied the value of $^E into $!, which caused much confusion.
2999 select() now supports all empty C<fd_set>s more correctly.
3003 C<'.\foo'> and C<'..\foo'> were treated differently than
3004 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
3008 Improved message window handling means that C<alarm> and C<kill> messages
3009 will no longer be dropped under race conditions.
3013 Various bits of Perl's build infrastructure are no longer converted to
3014 win32 line endings at release time. If this hurts you, please report the
3015 problem with the L<perlbug> program included with perl.
3022 =head1 Known Problems
3024 This is a list of some significant unfixed bugs, which are regressions
3025 from either 5.10.x or 5.8.x.
3031 Some CPANPLUS tests may fail if there is a functioning file
3032 F<../../cpanp-run-perl> outside your build directory. The failure
3033 shouldn't imply there's a problem with the actual functional
3034 software. The bug is already fixed in [RT #74188] and is scheduled for
3035 inclusion in perl-v5.12.1.
3039 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
3040 (typically introduced by C<my $_> or implicitly by C<given>). The variable
3041 which gets set for each iteration is the package variable C<$_>, not the
3042 lexical C<$_> [RT #67694].
3044 A similar issue may occur in other modules that provide functions which
3045 take a block as their first argument, like
3047 foo { ... $_ ...} list
3051 Some regexes may run much more slowly when run in a child thread compared
3052 with the thread the pattern was compiled into [RT #55600].
3056 Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
3057 will appear to hang as they get into a very long running loop [RT #72998].
3061 Several porters have reported mysterious crashes when Perl's entire
3062 test suite is run after a build on certain Windows 2000 systems. When
3063 run by hand, the individual tests reportedly work fine.
3073 This one is actually a change introduced in 5.10.0, but it was missed
3074 from that release's perldelta, so it is mentioned here instead.
3076 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
3077 in a change of behaviour between 5.8.x and 5.10.0:
3079 # matches in 5.8.x, doesn't match in 5.10.0
3080 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
3084 =head1 Acknowledgements
3086 Perl 5.12.0 represents approximately two years of development since
3087 Perl 5.10.0 and contains over 750,000 lines of changes across over
3088 3,000 files from over 200 authors and committers.
3090 Perl continues to flourish into its third decade thanks to a vibrant
3091 community of users and developers. The following people are known to
3092 have contributed the improvements that became Perl 5.12.0:
3094 Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
3095 Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
3096 Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
3097 andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
3098 Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
3099 Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
3100 Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
3101 Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
3102 Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
3103 Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
3104 David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
3105 Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
3106 Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
3107 Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
3108 Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
3109 Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
3110 Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
3111 Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
3112 Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
3113 John Peacock, John Peacock via RT, John P. Linderman, John Wright,
3114 Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
3115 Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
3116 Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
3117 Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
3118 Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
3119 G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
3120 Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
3121 Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
3122 Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
3123 Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
3124 Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
3125 Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
3126 Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
3127 Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
3128 Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
3129 Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
3130 The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
3131 Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
3132 Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
3133 Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
3135 This is woefully incomplete as it's automatically generated from version
3136 control history. In particular, it doesn't include the names of the
3137 (very much appreciated) contributors who reported issues in previous
3138 versions of Perl that helped make Perl 5.12.0 better. For a more complete
3139 list of all of Perl's historical contributors, please see the C<AUTHORS>
3140 file in the Perl 5.12.0 distribution.
3142 Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
3143 deserve special thanks for their brilliant and substantive ongoing
3144 contributions. Nicholas personally authored over 30% of the patches
3145 since 5.10.0. Rafael comes in second in patch authorship with 11%,
3146 but is first by a long shot in committing patches authored by others,
3147 pushing 44% of the commits since 5.10.0 in this category, often after
3148 providing considerable coaching to the patch authors. These statistics
3149 in no way comprise all of their contributions, but express in shorthand
3150 that we couldn't have done it without them.
3152 Many of the changes included in this version originated in the CPAN
3153 modules included in Perl's core. We're grateful to the entire CPAN
3154 community for helping Perl to flourish.
3156 =head1 Reporting Bugs
3158 If you find what you think is a bug, you might check the articles
3159 recently posted to the comp.lang.perl.misc newsgroup and the perl
3160 bug database at L<http://rt.perl.org/perlbug/>. There may also be
3161 information at L<http://www.perl.org/>, the Perl Home Page.
3163 If you believe you have an unreported bug, please run the B<perlbug>
3164 program included with your release. Be sure to trim your bug down
3165 to a tiny but sufficient test case. Your bug report, along with the
3166 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3167 analyzed by the Perl porting team.
3169 If the bug you are reporting has security implications, which make it
3170 inappropriate to send to a publicly archived mailing list, then please send
3171 it to perl5-security-report@perl.org. This points to a closed subscription
3172 unarchived mailing list, which includes
3173 all the core committers, who will be able
3174 to help assess the impact of issues, figure out a resolution, and help
3175 co-ordinate the release of patches to mitigate or fix the problem across all
3176 platforms on which Perl is supported. Please only use this address for
3177 security issues in the Perl core, not for modules independently
3178 distributed on CPAN.
3182 The F<Changes> file for an explanation of how to view exhaustive details
3185 The F<INSTALL> file for how to build Perl.
3187 The F<README> file for general stuff.
3189 The F<Artistic> and F<Copying> files for copyright information.
3191 L<http://dev.perl.org/perl5/errata.html> for a list of issues
3192 found after this release, as well as a list of CPAN modules known
3193 to be incompatible with this release.