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 allow 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> is now more flexible
204 The C<each> 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.pod>. 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 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 treates 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.
462 C<length undef> now returns undef.
466 Unsupported private C API functions are now declared "static" to prevent
467 leakage to Perl's public API.
471 To support the bootstrapping process, F<miniperl> no longer builds with
472 UTF-8 support in the regexp engine.
474 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
475 Without this there's a bootstrapping problem, as miniperl can't load
476 the UTF-8 components of the regexp engine, because they're not yet built.
480 F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
481 C<$ENV{PERL5LIB}>, and "C<.>"
485 A space or a newline is now required after a C<"#line XXX"> directive.
489 Tied filehandles now have an additional method EOF which provides the
494 To better match all other flow control statements, C<foreach> may no
495 longer be used as an attribute.
499 Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
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.
532 =item Use of C<:=> to mean an empty attribute list
534 An accident of Perl's parser meant that these constructions were all
541 with the C<:> being treated as the start of an attribute list, which
542 ends before the C<=>. As whitespace is not significant here, all are
543 parsed as an empty attribute list, hence all the above are equivalent
544 to, and better written as
548 because no attribute processing is done for an empty list.
550 As is, this meant that C<:=> cannot be used as a new token, without
551 silently changing the meaning of existing code. Hence that particular
552 form is now deprecated, and will become a syntax error. If it is
553 absolutely necessary to have empty attribute lists (for example,
554 because of a code generator) then avoid the warning by adding a space
557 =item C<< UNIVERSAL->import() >>
559 The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
560 pass import arguments to a C<use UNIVERSAL> statement will result in a
564 =item Use of "goto" to jump into a construct
566 Using C<goto> to jump from an outer scope into an inner scope is now
567 deprecated. This rare use case was causing problems in the
568 implementation of scopes.
570 =item Custom character names in \N{name} that don't look like names
572 In C<\N{I<name>}>, I<name> can be just about anything. The standard
573 Unicode names have a very limited domain, but a custom name translator
574 could create names that are, for example, made up entirely of punctuation
575 symbols. It is now deprecated to make names that don't begin with an
576 alphabetic character, and aren't alphanumeric or contain other than
577 a very few other characters, namely spaces, dashes, parentheses
578 and colons. Because of the added meaning of C<\N> (See L</C<\N>
579 experimental regex escape>), names that look like curly brace -enclosed
580 quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
581 4 non-newlines; before a custom name C<3,4> could have been created.
583 =item Deprecated Modules
585 The following modules will be removed from the core distribution in a
586 future release, and should be installed from CPAN instead. Distributions
587 on CPAN which require these should add them to their prerequisites. The
588 core versions of these modules warnings will issue a deprecation warning.
590 If you ship a packaged version of Perl, either alone or as part of a
591 larger system, then you should carefully consider the reprecussions of
592 core module deprecations. You may want to consider shipping your default
593 build of Perl with packages for some or all deprecated modules which
594 install into C<vendor> or C<site> perl library directories. This will
595 inhibit the deprecation warnings.
597 Alternatively, you may want to consider patching F<lib/deprecate.pm>
598 to provide deprecation warnings specific to your packaging system
599 or distribution of Perl, consistent with how your packaging system
600 or distribution manages a staged transition from a release where the
601 installation of a single package provides the given functionality, to
602 a later release where the system administrator needs to know to install
603 multiple packages to get that same functionality.
605 You can silence these deprecation warnings by installing the modules
606 in question from CPAN. To install the latest version of all of them,
607 just install C<Task::Deprecations::5_12>.
613 =item L<Pod::Plainer>
619 Switch is buggy and should be avoided. You may find Perl's new
620 C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
621 statements"> for more information.
625 =item Assignment to $[
627 =item Use of the attribute :locked on subroutines
629 =item Use of "locked" with the attributes pragma
631 =item Use of "unique" with the attributes pragma
635 C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
636 generates a deprecation warning, and it will be removed in a future
637 release. Although listed as part of the API, it was never documented,
638 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
639 core, it has been replaced by a static function.
641 =item Numerous Perl 4-era libraries
643 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
644 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
645 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
646 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
647 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
648 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
649 F<timelocal.pl> are all now deprecated. Using them will incur a warning.
654 =head1 Unicode overhaul
656 Perl's developers have made a concerted effort to update Perl to be in
657 sync with the latest Unicode standard. Changes for this include:
659 Perl can now handle every Unicode character property. New documentation,
660 L<perluniprops>, lists all available non-Unihan character properties. By
661 default, perl does not expose Unihan, deprecated or Unicode-internal
662 properties. See below for more details on these; there is also a section
663 in the pod listing them, and explaining why they are not exposed.
665 Perl now fully supports the Unicode compound-style of using C<=>
666 and C<:> in writing regular expressions: C<\p{property=value}> and
667 C<\p{property:value}> (both of which mean the same thing).
669 Perl now fully supports the Unicode loose matching rules for text between
670 the braces in C<\p{...}> constructs. In addition, Perl allows underscores
671 between digits of numbers.
673 Perl now accepts all the Unicode-defined synonyms for properties and
676 C<qr/\X/>, which matches a Unicode logical character, has
677 been expanded to work better with various Asian languages. It
678 now is defined as an I<extended grapheme cluster>. (See
679 L<http://www.unicode.org/reports/tr29/>). Anything matched previously
680 and that made sense will continue to be accepted. Additionally:
686 C<\X> will not break apart a C<S<CR LF>> sequence.
690 C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
695 C<\X> will now always match at least one character, including an initial
696 mark. Marks generally come after a base character, but it is possible in
697 Unicode to have them in isolation, and C<\X> will now handle that case,
698 for example at the beginning of a line, or after a C<ZWSP>. And this is
699 the part where C<\X> doesn't match the things that it used to that don't
700 make sense. Formerly, for example, you could have the nonsensical case
705 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
706 and Lao exception cases.
710 Otherwise, this change should be transparent for the non-affected
713 C<\p{...}> matches using the Canonical_Combining_Class property were
714 completely broken in previous releases of Perl. They should now work
717 Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
718 and a Perl extension had the same name, which led to neither matching
719 all the correct values (with more than 100 mistakes in one, and several
720 thousand in the other). The Perl extension has now been renamed to be
721 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
722 same meaning as was previously intended, namely the union of all the
723 non-canonical Decomposition types, with Unicode C<Compat> being just
726 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
728 C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
729 says they should. This means they each match a few more characters than
732 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
733 means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
734 nor Format (gc=cf) code points. The Format code points represent the
735 biggest possible problem. All but 36 of them are either officially
736 deprecated or strongly discouraged from being used. Of those 36, likely
737 the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
738 WJ, and similar characters, plus bidirectional controls.
740 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
741 5.12, Perl's definition definition included a number of things that aren't
742 really alpha (all marks) while omitting many that were. The definitions
743 of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
746 C<\p{Word}> no longer incorrectly matches non-word characters such
749 C<\p{Print}> no longer matches the line control characters: Tab, LF,
750 CR, FF, VT, and NEL. This brings it in line with standards and the
753 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
754 means that in addition to the characters it currently matches,
755 C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
756 example U+FF10: FULLWIDTH DIGIT ZERO.
758 The Numeric type property has been extended to include the Unihan
761 There is a new Perl extension, the 'Present_In', or simply 'In',
762 property. This is an extension of the Unicode Age property, but
763 C<\p{In=5.0}> matches any code point whose usage has been determined
764 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
765 added in I<precisely> version 5.0.
767 A number of properties now have the correct values for unassigned
768 code points. The affected properties are Bidi_Class, East_Asian_Width,
769 Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
772 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
773 are now up to date with current Unicode definitions.
775 Earlier versions of Perl erroneously exposed certain properties that
776 are supposed to be Unicode internal-only. Use of these in regular
777 expressions will now generate, if enabled, a deprecation warning message.
778 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
779 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
780 Other_Math, and Other_Uppercase.
782 It is now possible to change which Unicode properties Perl understands
783 on a per-installation basis. As mentioned above, certain properties
784 are turned off by default. These include all the Unihan properties
785 (which should be accessible via the CPAN module Unicode::Unihan) and any
786 deprecated or Unicode internal-only property that Perl has never exposed.
788 The generated files in the C<lib/unicore/To> directory are now more
789 clearly marked as being stable, directly usable by applications. New hash
790 entries in them give the format of the normal entries, which allows for
791 easier machine parsing. Perl can generate files in this directory for
792 any property, though most are suppressed. You can find instructions
793 for changing which are written in L<perluniprops>.
795 =head1 Modules and Pragmata
797 =head2 New Modules and Pragmata
803 C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
804 The bundled version is 2.06_01. Note that in this release, using a string
805 eval when C<autodie> is in effect can cause the autodie behaviour to leak
806 into the surrounding scope. See L<autodie/"BUGS"> for more details.
808 Version 2.06_01 has been added to the Perl core.
810 =item C<Compress::Raw::Bzip2>
812 Version 2.024 has been added to the Perl core.
816 C<overloading> allows you to lexically disable or enable overloading
817 for some or all operations.
819 Version 0.001 has been added to the Perl core.
823 C<parent> establishes an ISA relationship with base classes at compile
824 time. It provides the key feature of C<base> without further unwanted
827 Version 0.223 has been added to the Perl core.
829 =item C<Parse::CPAN::Meta>
831 Version 1.40 has been added to the Perl core.
835 Version 1.03 has been added to the Perl core.
839 Version 2.4 has been added to the Perl core.
841 =item C<XS::APItest::KeywordRPN>
843 Version 0.003 has been added to the Perl core.
847 =head2 Updated Pragmata
853 Upgraded from version 2.13 to 2.15.
857 Upgraded from version 0.22 to 0.23.
861 C<charnames> now contains the Unicode F<NameAliases.txt> database file.
862 This has the effect of adding some extra C<\N> character names that
863 formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
866 Upgraded from version 1.06 to 1.07.
870 Upgraded from version 1.13 to 1.20.
874 C<diagnostics> now supports %.0f formatting internally.
876 C<diagnostics> no longer suppresses C<Use of uninitialized value in range
877 (or flip)> warnings. [perl #71204]
879 Upgraded from version 1.17 to 1.19.
883 In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
884 bundles has changed slightly. The last component, if any (i.e. C<X>) is
885 simply ignored. This is predicated on the assumption that new features
886 will not, in general, be added to maintenance releases. So C<:5.10>
887 and C<:5.10.X> have identical effect. This is a change to the behaviour
888 documented for 5.10.0.
890 C<feature> now includes the C<unicode_strings> feature:
892 use feature "unicode_strings";
894 This pragma turns on Unicode semantics for the case-changing operations
895 (C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
896 internal UTF-8 flag set, but that contain single-byte characters between
899 Upgraded from version 1.11 to 1.16.
903 C<less> now includes the C<stash_name> method to allow subclasses of
904 C<less> to pick where in %^H to store their stash.
906 Upgraded from version 0.02 to 0.03.
910 Upgraded from version 0.5565 to 0.62.
914 C<mro> is now implemented as an XS extension. The documented interface has
915 not changed. Code relying on the implementation detail that some C<mro::>
916 methods happened to be available at all times gets to "keep both pieces".
918 Upgraded from version 1.00 to 1.02.
922 C<overload> now allow overloading of 'qr'.
924 Upgraded from version 1.06 to 1.10.
928 Upgraded from version 1.67 to 1.75.
930 =item C<threads::shared>
932 Upgraded from version 1.14 to 1.32.
936 C<version> now has support for L</Version number formats> as described
937 earlier in this document and in its own documentation.
939 Upgraded from version 0.74 to 0.82.
943 C<warnings> has a new C<warnings::fatal_enabled()> function. It also
944 includes a new C<illegalproto> warning category. See also L</New or
945 Changed Diagnostics> for this change.
947 Upgraded from version 1.06 to 1.09.
951 =head2 Updated Modules
955 =item C<Archive::Extract>
957 Upgraded from version 0.24 to 0.38.
959 =item C<Archive::Tar>
961 Upgraded from version 1.38 to 1.54.
963 =item C<Attribute::Handlers>
965 Upgraded from version 0.79 to 0.87.
969 Upgraded from version 5.63 to 5.70.
973 Upgraded from version 0.74 to 0.78.
977 Upgraded from version 1.05 to 1.12.
981 Upgraded from version 0.83 to 0.96.
985 Upgraded from version 1.09 to 1.11_01.
989 Upgraded from version 3.29 to 3.48.
993 Upgraded from version 0.33 to 0.36.
995 NOTE: C<Class::ISA> is deprecated and may be removed from a future
998 =item C<Compress::Raw::Zlib>
1000 Upgraded from version 2.008 to 2.024.
1004 Upgraded from version 1.9205 to 1.94_56.
1008 Upgraded from version 0.84 to 0.90.
1010 =item C<CPANPLUS::Dist::Build>
1012 Upgraded from version 0.06_02 to 0.46.
1014 =item C<Data::Dumper>
1016 Upgraded from version 2.121_14 to 2.125.
1020 Upgraded from version 1.816_1 to 1.820.
1022 =item C<Devel::PPPort>
1024 Upgraded from version 3.13 to 3.19.
1028 Upgraded from version 1.15 to 1.16.
1030 =item C<Digest::MD5>
1032 Upgraded from version 2.36_01 to 2.39.
1034 =item C<Digest::SHA>
1036 Upgraded from version 5.45 to 5.47.
1040 Upgraded from version 2.23 to 2.39.
1044 Upgraded from version 5.62 to 5.64_01.
1046 =item C<ExtUtils::CBuilder>
1048 Upgraded from version 0.21 to 0.27.
1050 =item C<ExtUtils::Command>
1052 Upgraded from version 1.13 to 1.16.
1054 =item C<ExtUtils::Constant>
1056 Upgraded from version 0.2 to 0.22.
1058 =item C<ExtUtils::Install>
1060 Upgraded from version 1.44 to 1.55.
1062 =item C<ExtUtils::MakeMaker>
1064 Upgraded from version 6.42 to 6.56.
1066 =item C<ExtUtils::Manifest>
1068 Upgraded from version 1.51_01 to 1.57.
1070 =item C<ExtUtils::ParseXS>
1072 Upgraded from version 2.18_02 to 2.21.
1074 =item C<File::Fetch>
1076 Upgraded from version 0.14 to 0.24.
1080 Upgraded from version 2.04 to 2.08_01.
1084 Upgraded from version 0.18 to 0.22.
1086 =item C<Filter::Simple>
1088 Upgraded from version 0.82 to 0.84.
1090 =item C<Filter::Util::Call>
1092 Upgraded from version 1.07 to 1.08.
1094 =item C<Getopt::Long>
1096 Upgraded from version 2.37 to 2.38.
1100 Upgraded from version 1.23_01 to 1.25_02.
1104 Upgraded from version 1.07 to 1.10.
1108 Upgraded from version 0.40_1 to 0.54.
1112 Upgraded from version 1.05 to 2.01.
1114 =item C<Locale::Maketext>
1116 Upgraded from version 1.12 to 1.14.
1118 =item C<Locale::Maketext::Simple>
1120 Upgraded from version 0.18 to 0.21.
1122 =item C<Log::Message>
1124 Upgraded from version 0.01 to 0.02.
1126 =item C<Log::Message::Simple>
1128 Upgraded from version 0.04 to 0.06.
1130 =item C<Math::BigInt>
1132 Upgraded from version 1.88 to 1.89_01.
1134 =item C<Math::BigInt::FastCalc>
1136 Upgraded from version 0.16 to 0.19.
1138 =item C<Math::BigRat>
1140 Upgraded from version 0.21 to 0.24.
1142 =item C<Math::Complex>
1144 Upgraded from version 1.37 to 1.56.
1148 Upgraded from version 1.01_02 to 1.01_03.
1150 =item C<MIME::Base64>
1152 Upgraded from version 3.07_01 to 3.08.
1154 =item C<Module::Build>
1156 Upgraded from version 0.2808_01 to 0.3603.
1158 =item C<Module::CoreList>
1160 Upgraded from version 2.12 to 2.29.
1162 =item C<Module::Load>
1164 Upgraded from version 0.12 to 0.16.
1166 =item C<Module::Load::Conditional>
1168 Upgraded from version 0.22 to 0.34.
1170 =item C<Module::Loaded>
1172 Upgraded from version 0.01 to 0.06.
1174 =item C<Module::Pluggable>
1176 Upgraded from version 3.6 to 3.9.
1180 Upgraded from version 2.33 to 2.36.
1184 Upgraded from version 0.60_01 to 0.64.
1186 =item C<Object::Accessor>
1188 Upgraded from version 0.32 to 0.36.
1190 =item C<Package::Constants>
1192 Upgraded from version 0.01 to 0.02.
1196 Upgraded from version 1.04 to 1.06.
1198 =item C<Pod::Parser>
1200 Upgraded from version 1.35 to 1.37.
1202 =item C<Pod::Perldoc>
1204 Upgraded from version 3.14_02 to 3.15_02.
1206 =item C<Pod::Plainer>
1208 Upgraded from version 0.01 to 1.02.
1210 NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
1213 =item C<Pod::Simple>
1215 Upgraded from version 3.05 to 3.13.
1219 Upgraded from version 2.12 to 2.22.
1223 Upgraded from version 1.11 to 1.17.
1227 Upgraded from version 2.18 to 2.22.
1231 Upgraded from version 2.13 to 2.16.
1233 NOTE: C<Switch> is deprecated and may be removed from a future version
1236 =item C<Sys::Syslog>
1238 Upgraded from version 0.22 to 0.27.
1240 =item C<Term::ANSIColor>
1242 Upgraded from version 1.12 to 2.02.
1246 Upgraded from version 0.18 to 0.20.
1250 Upgraded from version 1.25 to 1.25_02.
1252 =item C<Test::Harness>
1254 Upgraded from version 2.64 to 3.17.
1256 =item C<Test::Simple>
1258 Upgraded from version 0.72 to 0.94.
1260 =item C<Text::Balanced>
1262 Upgraded from version 2.0.0 to 2.02.
1264 =item C<Text::ParseWords>
1266 Upgraded from version 3.26 to 3.27.
1268 =item C<Text::Soundex>
1270 Upgraded from version 3.03 to 3.03_01.
1272 =item C<Thread::Queue>
1274 Upgraded from version 2.00 to 2.11.
1276 =item C<Thread::Semaphore>
1278 Upgraded from version 2.01 to 2.09.
1280 =item C<Tie::RefHash>
1282 Upgraded from version 1.37 to 1.38.
1284 =item C<Time::HiRes>
1286 Upgraded from version 1.9711 to 1.9719.
1288 =item C<Time::Local>
1290 Upgraded from version 1.18 to 1.1901_01.
1292 =item C<Time::Piece>
1294 Upgraded from version 1.12 to 1.15.
1296 =item C<Unicode::Collate>
1298 Upgraded from version 0.52 to 0.52_01.
1300 =item C<Unicode::Normalize>
1302 Upgraded from version 1.02 to 1.03.
1306 Upgraded from version 0.34 to 0.39.
1308 =item C<Win32API::File>
1310 Upgraded from version 0.1001_01 to 0.1101.
1314 Upgraded from version 0.08 to 0.10.
1318 =head2 Removed Modules and Pragmata
1324 Removed from the Perl core. Prior version was 1.02.
1326 =item C<CPAN::API::HOWTO>
1328 Removed from the Perl core. Prior version was 'undef'.
1330 =item C<CPAN::DeferedCode>
1332 Removed from the Perl core. Prior version was 5.50.
1334 =item C<CPANPLUS::inc>
1336 Removed from the Perl core. Prior version was 'undef'.
1340 Removed from the Perl core. Prior version was 1.03.
1342 =item C<ExtUtils::MakeMaker::bytes>
1344 Removed from the Perl core. Prior version was 6.42.
1346 =item C<ExtUtils::MakeMaker::vmsish>
1348 Removed from the Perl core. Prior version was 6.42.
1352 Removed from the Perl core. Prior version was 2.3.
1354 =item C<Test::Harness::Assert>
1356 Removed from the Perl core. Prior version was 0.02.
1358 =item C<Test::Harness::Iterator>
1360 Removed from the Perl core. Prior version was 0.02.
1362 =item C<Test::Harness::Point>
1364 Removed from the Perl core. Prior version was 0.01.
1366 =item C<Test::Harness::Results>
1368 Removed from the Perl core. Prior version was 0.01.
1370 =item C<Test::Harness::Straps>
1372 Removed from the Perl core. Prior version was 0.26_01.
1374 =item C<Test::Harness::Util>
1376 Removed from the Perl core. Prior version was 0.01.
1380 Removed from the Perl core. Prior version was 1.1.
1384 =head2 Deprecated Modules and Pragmata
1386 See L</Deprecated Modules> above.
1389 =head1 Documentation
1391 =head2 New Documentation
1397 L<perlhaiku> contains instructions on how to build perl for the Haiku
1402 L<perlmroapi> describes the new interface for pluggable Method Resolution
1407 L<perlperf>, by Richard Foley, provides an introduction to the use of
1408 performance and optimization techniques which can be used with particular
1409 reference to perl programs.
1413 L<perlrepository> describes how to access the perl source using the I<git>
1414 version control system.
1418 L<perlpolicy> extends the "Social contract about contributed modules" into
1419 the beginnings of a document on Perl porting policies.
1423 =head2 Changes to Existing Documentation
1431 The various large F<Changes*> files (which listed every change made
1432 to perl over the last 18 years) have been removed, and replaced by a
1433 small file, also called F<Changes>, which just explains how that same
1434 information may be extracted from the git version control system.
1438 F<Porting/patching.pod> has been deleted, as it mainly described
1439 interacting with the old Perforce-based repository, which is now obsolete.
1440 Information still relevant has been moved to L<perlrepository>.
1445 The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
1446 as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
1447 BLOCK>, although actually using the latter may not be the best idea for
1448 the readability of your source code.
1453 Documented -X overloading.
1457 Documented that C<when()> treats specially most of the filetest operators
1461 Documented C<when> as a syntax modifier.
1465 Eliminated "Old Perl threads tutorial", which described 5005 threads.
1467 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1471 Correct previous documentation: v-strings are not deprecated
1473 With version objects, we need them to use MODULE VERSION syntax. This
1474 patch removes the deprecation notice.
1478 Security contact information is now part of L<perlsec>.
1482 A significant fraction of the core documentation has been updated to
1483 clarify the behavior of Perl's Unicode handling.
1485 Much of the remaining core documentation has been reviewed and edited
1486 for clarity, consistent use of language, and to fix the spelling of Tom
1487 Christiansen's name.
1491 The Pod specification (L<perlpodspec>) has been updated to bring the
1492 specification in line with modern usage already supported by most Pod
1493 systems. A parameter string may now follow the format name in a
1494 "begin/end" region. Links to URIs with a text description are now
1495 allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
1500 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1501 conditional loading of modules despite the implicit BEGIN block around
1506 The documentation for C<$1> in perlvar.pod has been clarified.
1510 C<\N{U+I<wide hex char>}> is now documented.
1514 =head1 Selected Performance Enhancements
1520 A new internal cache means that C<isa()> will often be faster.
1524 The implementation of C<C3> Method Resolution Order has been
1525 optimised - linearisation for classes with single inheritance is 40%
1526 faster. Performance for multiple inheritance is unchanged.
1530 Under C<use locale>, the locale-relevant information is now cached on
1531 read-only values, such as the list returned by C<keys %hash>. This makes
1532 operations such as C<sort keys %hash> in the scope of C<use locale>
1537 Empty C<DESTROY> methods are no longer called.
1541 C<Perl_sv_utf8_upgrade()> is now faster.
1545 C<keys> on empty hash is now faster.
1549 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
1553 The string repetition operator (C<$str x $num>) is now several times
1554 faster when C<$str> has length one or C<$num> is large.
1558 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1559 now happens in-place and is several orders of magnitude faster than
1560 it used to be. It will also preserve non-existent elements whenever
1561 possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
1562 and C<DELETE> methods.
1566 =head1 Installation and Configuration Improvements
1572 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
1573 generated at build time, rather than being shipped as part of the release.
1577 If C<vendorlib> and C<vendorarch> are the same, then they are only added
1582 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1583 perl is built with C<-Dusedevel>.
1587 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1588 against stack-smashing attacks, if the compiler supports it.
1592 F<Configure> will now determine the correct prototypes for re-entrant
1593 functions and for C<gconvert> if you are using a C++ compiler rather
1598 On Unix, if you build from a tree containing a git repository, the
1599 configuration process will note the commit hash you have checked out, for
1600 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1601 are automatically added to the list of local patches displayed by
1606 Perl now supports SystemTap's C<dtrace> compatibility layer and an
1607 issue with linking C<miniperl> has been fixed in the process.
1611 perldoc now uses C<less -R> instead of C<less> for improved behaviour
1612 in the face of C<groff>'s new usage of ANSI escape codes.
1617 C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
1618 C<USE_ATTRIBUTES_FOR_PERLIO>.
1622 As part of the flattening of F<ext>, all extensions on all platforms are
1623 built by F<make_ext.pl>. This replaces the Unix-specific
1624 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1625 F<win32/buildext.pl>.
1629 =head1 Internal Changes
1631 Each release of Perl sees numerous internal changes which shouldn't
1632 affect day to day usage but may still be notable for developers working
1633 with Perl's source code.
1639 The J.R.R. Tolkien quotes at the head of C source file have been checked
1640 and proper citations added, thanks to a patch from Tom Christiansen.
1644 The internal structure of the dual-life modules traditionally found in
1645 the F<lib/> and F<ext/> directories in the perl source has changed
1646 significantly. Where possible, dual-lifed modules have been extracted
1647 from F<lib/> and F<ext/>.
1649 Dual-lifed modules maintained by Perl's developers as part of the Perl
1650 core now live in F<dist/>. Dual-lifed modules maintained primarily on
1651 CPAN now live in F<cpan/>. When reporting a bug in a module located
1652 under F<cpan/>, please send your bug report directly to the module's
1653 bug tracker or author, rather than Perl's bug tracker.
1657 C<\N{...}> now compiles better, always forces UTF-8 internal representation
1659 Perl's developers have fixed several problems with the recognition of
1660 C<\N{...}> constructs. As part of this, perl will store any scalar
1661 or regex containing C<\N{I<name>}> or C<\N{U+I<wide hex char>}> in its
1662 definition in UTF-8 format. (This was true previously for all occurences
1663 of C<\N{I<name>}> that did not use a custom translator, but now it's
1668 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1672 C<SVt_RV> no longer exists. RVs are now stored in IVs.
1676 C<Perl_vcroak()> now accepts a null first argument. In addition, a full
1677 audit was made of the "not NULL" compiler annotations, and those for
1678 several other internal functions were corrected.
1682 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1683 have been added to formalise the temporary saving of the C<errno>
1688 The function C<Perl_sv_insert_flags> has been added to augment
1693 The function C<Perl_newSV_type(type)> has been added, equivalent to
1694 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1698 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1699 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1701 Two flag bits are currently supported.
1707 C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
1708 not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
1709 C<newSVpvn_utf8()> is available for this.
1713 C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
1717 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1721 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1726 Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
1730 C<PL_na> has been exterminated from the core code, replaced by local
1731 STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
1732 C<PL_na>, which is a pointer dereference into the interpreter structure
1733 under ithreads, and a global variable otherwise.
1737 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
1738 on the scalar. It now updates the linked list to remove each piece of
1739 magic as it is freed.
1743 Under ithreads, the regex in C<PL_reg_curpm> is now reference
1744 counted. This eliminates a lot of hackish workarounds to cope with it
1745 not being reference counted.
1749 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1750 This has been fixed.
1754 The I<public> IV and NV flags are now not set if the string value has
1755 trailing "garbage". This behaviour is consistent with not setting the
1756 public IV or NV flags if the value is out of range for the type.
1760 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
1761 been replaced by C<NULL> in the core code, and non-dual-life modules,
1762 as C<NULL> is clearer to those unfamiliar with the core code.
1766 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1767 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1768 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1769 casting away C<const>. This allows proper compile-time auditing of
1770 C<const> correctness in the core, and helped picked up some errors
1775 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1776 stack and mortalizing them.
1780 Use of the private structure C<mro_meta> has changed slightly. Nothing
1781 outside the core should be accessing this directly anyway.
1785 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1786 to view how a C preprocessor macro would be expanded when compiled.
1787 This is handy when trying to decode the macro hell that is the perl
1794 =head2 Testing improvements
1798 =item Parallel tests
1800 The core distribution can now run its regression tests in parallel on
1801 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
1802 your environment to the number of tests to run in parallel, and run
1803 C<make test_harness>. On a Bourne-like shell, this can be done as
1805 TEST_JOBS=3 make test_harness # Run 3 tests in parallel
1807 An environment variable is used, rather than parallel make itself, because
1808 L<TAP::Harness> needs to be able to schedule individual non-conflicting test
1809 scripts itself, and there is no standard interface to C<make> utilities to
1810 interact with their job schedulers.
1812 Note that currently some test scripts may fail when run in parallel (most
1813 notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
1814 again sequentially and see if the failures go away.
1816 =item Test harness flexibility
1818 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1822 Several tests that have the potential to hang forever if they fail now
1823 incorporate a "watchdog" functionality that will kill them after a timeout,
1824 which helps ensure that C<make test> and C<make test_harness> run to
1825 completion automatically.
1832 Perl's developers have added a number of new tests to the core.
1833 In addition to the items listed below, many modules updated from CPAN
1834 incorporate new tests.
1840 Significant cleanups to core tests to ensure that language and
1841 interpreter features are not used before they're tested.
1845 C<make test_porting> now runs a number of important pre-commit checks
1846 which might be of use to anyone working on the Perl core.
1850 F<t/porting/podcheck.t> automatically checks the well-formedness of
1851 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1852 dual-lifed modules which are primarily maintained outside the Perl core.
1856 F<t/porting/manifest.t> now tests that all files listed in MANIFEST
1861 F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
1865 F<t/comp/retainedlines.t> checks that the debugger can retain source
1870 F<t/io/perlio_fail.t> checks that bad layers fail.
1874 F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
1878 F<t/io/perlio_open.t> checks that certain special forms of open work.
1882 F<t/io/perlio.t> includes general PerlIO tests.
1886 F<t/io/pvbm.t> checks that there is no unexpected interaction between
1887 the internal types C<PVBM> and C<PVGV>.
1891 F<t/mro/package_aliases.t> checks that mro works properly in the presence
1892 of aliased packages.
1896 F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
1900 F<t/op/index_thr.t> tests the interaction of C<index> and threads.
1904 F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
1908 F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
1912 F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
1916 F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
1917 embedded C<qr//> and threads.
1921 F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
1926 F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
1927 properties and threads.
1931 F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
1935 F<t/op/reg_posixcc.t> checks that POSIX character classes behave
1940 F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
1944 F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
1948 F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
1952 F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
1956 F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
1960 F<t/uni/tie.t> checks that Unicode and C<tie> work.
1964 F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
1968 F<t/comp/form_scope.t> tests format scoping.
1972 F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
1976 F<t/op/filetest_t.t> tests if -t file test works.
1980 F<t/op/qr.t> tests C<qr>.
1984 F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
1988 F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
1992 F<t/op/filehandle.t> tests some suitably portable filetest operators
1993 to check that they work as expected, particularly in the light of some
1994 internal changes made in how filehandles are blessed.
1998 F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
1999 can now be handed to C<gmtime> and C<localtime>, do not cause an internal
2000 overflow or an excessively long loop.
2005 =head1 New or Changed Diagnostics
2007 =head2 New Diagnostics
2013 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
2014 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
2015 that was enabled when the F<perl> binary was compiled.
2019 Smartmatch resolution tracing has been added as a new diagnostic. Use
2020 C<-DM> to enable it.
2024 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
2025 C<-Dx> for its original purpose of dumping syntax trees.
2029 Perl 5.12 provides a number of new diagnostic messages to help you write
2030 better code. See L<perldiag> for details of these new messages.
2036 C<Bad plugin affecting keyword '%s'>
2040 C<gmtime(%.0f) too large>
2044 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
2048 C<Lexing code internal error (%s)>
2052 C<localtime(%.0f) too large>
2056 C<Overloaded dereference did not return a reference>
2060 C<Overloaded qr did not return a REGEXP>
2064 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
2068 C<lvalue attribute ignored after the subroutine has been defined>
2070 This new warning is issued when one attempts to mark a subroutine as
2071 lvalue after it has been defined.
2075 Perl now warns you if C<++> or C<--> are unable to change the value
2076 because it's beyond the limit of representation.
2078 This uses a new warnings category: "imprecision".
2082 C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
2086 C<Show constant in "Useless use of a constant in void context">
2090 C<Prototype after '%s'>
2094 C<panic: sv_chop %s>
2096 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
2097 passed a position that is not within the scalar's string buffer. This
2098 could be caused by buggy XS code, and at this point recovery is not
2104 The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
2105 C<charnames> handler returns malformed UTF-8.
2109 If an unresolved named character or sequence was encountered when
2110 compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
2111 by the lexer> is now produced. This can happen, for example, when using a
2112 single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
2113 for more examples of how the lexer can get bypassed.
2117 C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
2118 triggered when the character constant represented by C<...> is not a
2119 valid hexadecimal number.
2123 The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
2124 class, just like C<.> in a character class loses its special meaning,
2125 and will cause the fatal error C<\N in a character class must be a named
2126 character: \N{...}>.
2130 The rules on what is legal for the C<...> in C<\N{...}> have been
2131 tightened up so that unless the C<...> begins with an alphabetic
2132 character and continues with a combination of alphanumerics, dashes,
2133 spaces, parentheses or colons then the warning C<Deprecated character(s)
2134 in \N{...} starting at '%s'> is now issued.
2138 The warning C<Using just the first characters returned by \N{}> will
2139 be issued if the C<charnames> handler returns a sequence of characters
2140 which exceeds the limit of the number of characters that can be used. The
2141 message will indicate which characters were used and which were discarded.
2147 =head2 Changed Diagnostics
2149 A number of existing diagnostic messages have been improved or corrected:
2155 A new warning category C<illegalproto> allows finer-grained control of
2156 warnings around function prototypes.
2162 =item C<Illegal character in prototype for %s : %s>
2164 =item C<Prototype after '%c' for %s : %s>
2168 have been moved from the C<syntax> top-level warnings category into a new
2169 first-level category, C<illegalproto>. These two warnings are currently
2170 the only ones emitted during parsing of an invalid/illegal prototype,
2173 no warnings 'illegalproto';
2175 to suppress only those, but not other syntax-related warnings. Warnings
2176 where prototypes are changed, ignored, or not met are still in the
2177 C<prototype> category as before.
2181 C<Deep recursion on subroutine "%s">
2183 It is now possible to change the depth threshold for this warning from the
2184 default of 100, by recompiling the F<perl> binary, setting the C
2185 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
2189 C<Illegal character in prototype> warning is now more precise
2190 when reporting illegal characters after _
2194 mro merging error messages are now very similar to those produced by
2199 Amelioration of the error message "Unrecognized character %s in column %d"
2201 Changes the error message to "Unrecognized character %s; marked by E<lt>--
2202 HERE after %sE<lt>-- HERE near column %d". This should make it a little
2203 simpler to spot and correct the suspicious character.
2207 Perl now explicitly points to C<$.> when it causes an uninitialized
2208 warning for ranges in scalar context.
2212 C<split> now warns when called in void context.
2216 C<printf>-style functions called with too few arguments will now issue the
2217 warning C<"Missing argument in %s"> [perl #71000]
2221 Perl now properly returns a syntax error instead of segfaulting
2222 if C<each>, C<keys>, or C<values> is used without an argument.
2226 C<tell()> now fails properly if called without an argument and when no
2227 previous file was read.
2229 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
2230 the 5.8.x behaviour.
2234 C<overload> no longer implicitly unsets fallback on repeated 'use
2239 POSIX::strftime() can now handle Unicode characters in the format string.
2243 The C<syntax> category was removed from 5 warnings that should only be in
2248 Three fatal C<pack>/C<unpack> error messages have been normalized to
2253 C<Unicode character is illegal> has been rephrased to be more accurate
2255 It now reads C<Unicode non-character is illegal in interchange> and the
2256 perldiag documentation has been expanded a bit.
2260 Currently, all but the first of the several characters that the
2261 C<charnames> handler may return are discarded when used in a regular
2262 expression pattern bracketed character class. If this happens then the
2263 warning C<Using just the first character returned by \N{} in character
2264 class> will be issued.
2268 The warning C<Missing right brace on \N{} or unescaped left brace after
2269 \N. Assuming the latter> will be issued if Perl encounters a C<\N{>
2270 but doesn't find a matching C<}>. In this case Perl doesn't know if it
2271 was mistakenly omitted, or if "match non-newline" followed by "match
2272 a C<{>" was desired. It assumes the latter because that is actually a
2273 valid interpretation as written, unlike the other case. If you meant
2274 the former, you need to add the matching right brace. If you did mean
2275 the latter, you can silence this warning by writing instead C<\N\{>.
2279 C<gmtime> and C<localtime> called with numbers smaller than they can
2280 reliably handle will now issue the warnings C<gmtime(%.0f) too small>
2281 and C<localtime(%.0f) too small>.
2285 The following diagnostic messages have been removed:
2295 C<Can't locate package %s for the parents of %s>
2297 In general this warning it only got produced in
2298 conjunction with other warnings, and removing it allowed an ISA lookup
2299 optimisation to be added.
2303 C<v-string in use/require is non-portable>
2307 =head1 Utility Changes
2313 F<h2ph> now looks in C<include-fixed> too, which is a recent addition
2314 to gcc's search path.
2318 F<h2xs> no longer incorrectly treats enum values like macros.
2319 It also now handles C++ style comments (C<//>) properly in enums.
2323 F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
2324 debugger now correctly handles proxy constant subroutines, and
2329 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
2330 upstream bug tracker URLs. If a user identifies a particular module
2331 as the topic of their bug report and we're able to divine the URL for
2332 its upstream bug tracker, perlbug now provide a message to the user
2333 explaining that the core copies the CPAN version directly, and provide
2334 the URL for reporting the bug directly to the upstream author.
2336 F<perlbug> no longer reports "Message sent" when it hasn't actually sent
2341 F<perlthanks> is a new utility for sending non-bug-reports to the
2342 authors and maintainers of Perl. Getting nothing but bug reports can
2343 become a bit demoralising. If Perl 5.12 works well for you, please try
2344 out F<perlthanks>. It will make the developers smile.
2348 Perl's developers have fixed bugs in F<a2p> having to do with the
2349 C<match()> operator in list context. Additionally, F<a2p> no longer
2350 generates code that uses the C<$[> variable.
2354 =head1 Selected Bug Fixes
2360 U+0FFFF is now a legal character in regular expressions.
2364 pp_qr now always returns a new regexp SV. Resolves RT #69852.
2366 Instead of returning a(nother) reference to the (pre-compiled) regexp
2367 in the optree, use reg_temp_copy() to create a copy of it, and return a
2368 reference to that. This resolves issues about Regexp::DESTROY not being
2369 called in a timely fashion (the original bug tracked by RT #69852), as
2370 well as bugs related to blessing regexps, and of assigning to regexps,
2371 as described in correspondence added to the ticket.
2373 It transpires that we also need to undo the SvPVX() sharing when ithreads
2374 cloning a Regexp SV, because mother_re is set to NULL, instead of a
2375 cloned copy of the mother_re. This change might fix bugs with regexps
2376 and threads in certain other situations, but as yet neither tests nor
2377 bug reports have indicated any problems, so it might not actually be an
2378 edge case that it's possible to reach.
2382 Several compilation errors and segfaults when perl was built with C<-Dmad>
2387 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
2391 C<-t> should only return TRUE for file handles connected to a TTY
2393 The Microsoft C version of C<isatty()> returns TRUE for all character mode
2394 devices, including the F</dev/null>-style "nul" device and printers like
2399 Fixed a regression caused by commit fafafbaf which caused a panic during
2400 parameter passing [perl #70171]
2404 On systems which in-place edits without backup files, -i'*' now works as
2405 the documentation says it does [perl #70802]
2409 Saving and restoring magic flags no longer loses readonly flag.
2413 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
2414 causes abrupt and total failure.
2418 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
2423 Using named subroutines with C<sort> should no longer lead to bus errors
2428 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
2432 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
2436 C<$@> may now be assigned a read-only value (without error or busting
2441 C<sort> called recursively from within an active comparison subroutine no
2442 longer causes a bus error if run multiple times. [perl #71076]
2446 Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
2450 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
2455 C<-I> on shebang line now adds directories in front of @INC
2456 as documented, and as does C<-I> when specified on the command-line.
2460 C<kill> is now fatal when called on non-numeric process identifiers.
2461 Previously, an C<undef> process identifier would be interpreted as a
2462 request to kill process 0, which would terminate the current process
2463 group on POSIX systems. Since process identifiers are always integers,
2464 killing a non-numeric process is now fatal.
2468 5.10.0 inadvertently disabled an optimisation, which caused a measurable
2469 performance drop in list assignment, such as is often used to assign
2470 function parameters from C<@_>. The optimisation has been re-instated, and
2471 the performance regression fixed. (This fix is also present in 5.10.1)
2475 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
2479 Some potential coredumps in PerlIO fixed [RT #57322,54828].
2483 The debugger now works with lvalue subroutines.
2487 The debugger's C<m> command was broken on modules that defined constants
2492 C<crypt> and string complement could return tainted values for untainted
2493 arguments [RT #59998].
2497 The C<-i>I<.suffix> command-line switch now recreates the file using
2498 restricted permissions, before changing its mode to match the original
2499 file. This eliminates a potential race condition [RT #60904].
2503 On some Unix systems, the value in C<$?> would not have the top bit set
2504 (C<$? & 128>) even if the child core dumped.
2508 Under some circumstances, C<$^R> could incorrectly become undefined
2513 In the XS API, various hash functions, when passed a pre-computed hash where
2514 the key is UTF-8, might result in an incorrect lookup.
2518 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2523 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
2524 didn't exist, even if the object's C<@ISA> contained C<Foo>.
2528 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2529 C<@ISA>, have been found and fixed.
2533 Bitwise operations on references could crash the interpreter, e.g.
2534 C<$x=\$y; $x |= "foo"> [RT #54956].
2538 Patterns including alternation might be sensitive to the internal UTF-8
2539 representation, e.g.
2541 my $byte = chr(192);
2542 my $utf8 = chr(192); utf8::upgrade($utf8);
2543 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2547 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2548 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2549 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2550 greater than 255 [RT #59908].
2554 C<B::Deparse> failed to correctly deparse various constructs:
2555 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2556 C<sub foo(_)> [RT #62484].
2560 Using C<setpgrp> with no arguments could corrupt the perl stack.
2564 The block form of C<eval> is now specifically trappable by C<Safe> and
2565 C<ops>. Previously it was erroneously treated like string C<eval>.
2569 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2570 match operator (C<~~>) [RT #63854].
2574 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2575 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2577 ("ab" x 32768) =~ /^(ab)*$/
2581 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2585 Using C<next> or C<last> to exit a C<given> block no longer produces a
2586 spurious warning like the following:
2588 Exiting given via last at foo.pl line 123
2592 Assigning a format to a glob could corrupt the format; e.g.:
2594 *bar=*foo{FORMAT}; # foo format now bad
2598 Attempting to coerce a typeglob to a string or number could cause an
2599 assertion failure. The correct error message is now generated,
2600 C<Can't coerce GLOB to I<$type>>.
2604 Under C<use filetest 'access'>, C<-x> was using the wrong access
2605 mode. This has been fixed [RT #49003].
2609 C<length> on a tied scalar that returned a Unicode value would not be
2610 correct the first time. This has been fixed.
2614 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2619 A race condition inside C<PerlIOStdio_close()> has been identified and
2620 fixed. This used to cause various threading issues, including SEGVs.
2624 In C<unpack>, the use of C<()> groups in scalar context was internally
2625 placing a list on the interpreter's stack, which manifested in various
2626 ways, including SEGVs. This is now fixed [RT #50256].
2630 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2631 These have all been fixed.
2635 A 5.10.0 optimisation to clear the temporary stack within the implicit
2636 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2637 obscure bugs in seemingly unrelated parts of the interpreter [commit
2642 The line numbers for warnings inside C<elsif> are now correct.
2646 The C<..> operator now works correctly with ranges whose ends are at or
2647 close to the values of the smallest and largest integers.
2651 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2652 This has been fixed [RT #54828].
2656 An off-by-one error meant that C<index $str, ...> was effectively being
2657 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2661 Various leaks associated with named captures in regexes have been fixed
2666 A weak reference to a hash would leak. This was affecting C<DBI>
2671 Using (?|) in a regex could cause a segfault [RT #59734].
2675 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2679 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2680 unaligned 64-bit access on the SPARC architecture [RT #60574].
2684 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2685 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2690 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2695 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2696 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2701 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2702 missed (method cache issue) [RT #60220,60232].
2706 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2707 cause a memory leak [RT #63110].
2711 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2712 specified on the command line. C<-C> on the shebang line used to be a
2713 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2714 disallowed it, which broke some scripts. Now perl checks whether it is
2715 also on the command line and only dies if it is not [RT #67880].
2719 In 5.10.0, certain types of re-entrant regular expression could crash,
2720 or cause the following assertion failure [RT #60508]:
2722 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2726 Perl now includes previously missing files from the Unicode Character
2731 Perl now honors C<TMPDIR> when opening an anonymous temporary file.
2736 =head1 Platform Specific Changes
2738 Perl is incredibly portable. In general, if a platform has a C compiler,
2739 someone has ported Perl to it (or will soon). We're happy to announce
2740 that Perl 5.12 includes support for several new platforms. At the same
2741 time, it's time to bid farewell to some (very) old friends.
2743 =head2 New Platforms
2749 Perl's developers have merged patches from Haiku's maintainers. Perl
2750 should now build on Haiku.
2754 Perl should now build on MirOS BSD.
2758 =head2 Discontinued Platforms
2770 =head2 Updated Platforms
2780 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
2785 Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
2786 installed. The F<libgdbm> is delivered as an optional package with the
2787 AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
2791 Hints changes mean that AIX 4.2 should work again.
2801 Perl now supports IPv6 on Cygwin 1.7 and newer.
2805 On Cygwin we now strip the last number from the DLL. This has been the
2806 behaviour in the cygwin.com build for years. The hints files have been
2811 =item Darwin (Mac OS X)
2817 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2818 as it's still buggy.
2822 Correct infelicities in the regexp used to identify buggy locales
2823 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2833 Fix thread library selection [perl #69686]
2843 The hints files now identify the correct threading libraries on FreeBSD 7
2854 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2855 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2865 Hints now supports versions 5.*.
2875 C<-UDEBUGGING> is now the default on VMS.
2877 Like it has been everywhere else for ages and ages. Also make command-line
2878 selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
2879 the only way to turn it off was by saying no in answer to the interactive
2884 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2889 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2890 if C<$/> was set to a numeric reference (to indicate record-style reads).
2895 VMS now supports C<getgrgid>.
2899 Many improvements and cleanups have been made to the VMS file name handling
2900 and conversion code.
2904 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2905 status in a VMS condition value for better interaction with GNV's bash
2906 shell and other utilities that depend on POSIX exit values. See
2907 L<perlvms/"$?"> for details.
2911 C<File::Copy> now detects Unix compatibility mode on VMS.
2921 Various changes from Stratus have been merged in.
2931 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2941 Perl 5.12 supports Windows 2000 and later. The supporting code for
2942 legacy versions of Windows is still included, but will be removed
2943 during the next development cycle.
2947 Initial support for building Perl with MinGW-w64 is now available.
2951 F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
2952 settings for Windows Vista and later. Without this setting Windows
2953 would treat F<perl.exe> as a legacy application and apply various
2954 heuristics like redirecting access to protected file system areas
2955 (like the "Program Files" folder) to the users "VirtualStore"
2956 instead of generating a proper "permission denied" error.
2958 The manifest resource also requests the Microsoft Common-Controls
2959 version 6.0 (themed controls introduced in Windows XP). Check out the
2960 Win32::VisualStyles module on CPAN to switch back to old style
2961 unthemed controls for legacy applications.
2965 The C<-t> filetest operator now only returns true if the filehandle
2966 is connected to a console window. In previous versions of Perl it
2967 would return true for all character mode devices, including F<NUL>
2972 The C<-p> filetest operator now works correctly, and the
2973 Fcntl::S_IFIFO constant is defined when Perl is compiled with
2974 Microsoft Visual C. In previous Perl versions C<-p> always
2975 returned a false value, and the Fcntl::S_IFIFO constant
2978 This bug is specific to Microsoft Visual C and never affected
2979 Perl binaries built with MinGW.
2983 The socket error codes are now more widely supported: The POSIX
2984 module will define the symbolic names, like POSIX::EWOULDBLOCK,
2985 and stringification of socket error codes in $! works as well
2988 C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
2989 A non-blocking socket operation could not be completed immediately.
2993 flock() will now set sensible error codes in $!. Previous Perl versions
2994 copied the value of $^E into $!, which caused much confusion.
2998 select() now supports all empty C<fd_set>s more correctly.
3002 C<'.\foo'> and C<'..\foo'> were treated differently than
3003 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
3007 Improved message window handling means that C<alarm> and C<kill> messages
3008 will no longer be dropped under race conditions.
3012 Various bits of Perl's build infrastructure are no longer converted to
3013 win32 line endings at release time. If this hurts you, please report the
3014 problem with the L<perlbug> program included with perl.
3021 =head1 Known Problems
3023 This is a list of some significant unfixed bugs, which are regressions
3024 from either 5.10.x or 5.8.x.
3030 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
3031 (typically introduced by C<my $_> or implicitly by C<given>). The variable
3032 which gets set for each iteration is the package variable C<$_>, not the
3033 lexical C<$_> [RT #67694].
3035 A similar issue may occur in other modules that provide functions which
3036 take a block as their first argument, like
3038 foo { ... $_ ...} list
3042 Some regexes may run much more slowly when run in a child thread compared
3043 with the thread the pattern was compiled into [RT #55600].
3047 Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
3048 will appear to hang as they get into a very long running loop [RT #72998].
3052 Several porters have reported mysterious crashes when Perl's entire
3053 test suite is run after a build on certain Windows 2000 systems. When
3054 run by hand, the individual tests reportedly work fine.
3064 This one is actually a change introduced in 5.10.0, but it was missed
3065 from that release's perldelta, so it is mentioned here instead.
3067 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
3068 in a change of behaviour between 5.8.x and 5.10.0:
3070 # matches in 5.8.x, doesn't match in 5.10.0
3071 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
3075 =head1 Acknowledgements
3077 Perl 5.12.0 represents approximately two years of development since
3078 Perl 5.10.0 and contains over 750,000 lines of changes across over
3079 3,000 files from over 200 authors and committers.
3081 Perl continues to flourish into its third decade thanks to a vibrant
3082 community of users and developers. The following people are known to
3083 have contributed the improvements that became Perl 5.12.0:
3085 Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
3086 Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
3087 Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
3088 andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
3089 Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
3090 Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
3091 Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
3092 Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
3093 Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
3094 Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
3095 David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
3096 Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
3097 Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
3098 Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
3099 Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
3100 Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
3101 Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
3102 Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
3103 Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
3104 John Peacock, John Peacock via RT, John P. Linderman, John Wright,
3105 Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
3106 Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
3107 Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
3108 Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
3109 Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
3110 G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
3111 Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
3112 Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
3113 Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
3114 Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
3115 Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
3116 Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
3117 Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
3118 Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
3119 Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
3120 Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
3121 The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
3122 Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
3123 Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
3124 Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
3126 This is woefully incomplete as it's automatically generated from version
3127 control history. In particular, it doesn't include the names of the
3128 (very much appreciated) contributors who reported issues in previous
3129 versions of Perl that helped make Perl 5.12.0 better. For a more complete
3130 list of all of Perl's historical contributors, please see the C<AUTHORS>
3131 file in the Perl 5.12.0 distribution.
3133 Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
3134 deserve special thanks for their brilliant and substantive ongoing
3135 contributions. Nicholas personally authored over 30% of the patches
3136 since 5.10.0. Rafael comes in second in patch authorship with 11%,
3137 but is first by a long shot in committing patches authored by others,
3138 pushing 44% of the commits since 5.10.0 in this category, often after
3139 providing considerable coaching to the patch authors. These statistics
3140 in no way comprise all of their contributions, but express in shorthand
3141 that we couldn't have done it without them.
3143 Many of the changes included in this version originated in the CPAN
3144 modules included in Perl's core. We're grateful to the entire CPAN
3145 community for helping Perl to flourish.
3147 =head1 Reporting Bugs
3149 If you find what you think is a bug, you might check the articles
3150 recently posted to the comp.lang.perl.misc newsgroup and the perl
3151 bug database at L<http://rt.perl.org/perlbug/>. There may also be
3152 information at L<http://www.perl.org/>, the Perl Home Page.
3154 If you believe you have an unreported bug, please run the B<perlbug>
3155 program included with your release. Be sure to trim your bug down
3156 to a tiny but sufficient test case. Your bug report, along with the
3157 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3158 analyzed by the Perl porting team.
3160 If the bug you are reporting has security implications, which make it
3161 inappropriate to send to a publicly archived mailing list, then please send
3162 it to perl5-security-report@perl.org. This points to a closed subscription
3163 unarchived mailing list, which includes all the core committers, who be able
3164 to help assess the impact of issues, figure out a resolution, and help
3165 co-ordinate the release of patches to mitigate or fix the problem across all
3166 platforms on which Perl is supported. Please only use this address for
3167 security issues in the Perl core, not for modules independently
3168 distributed on CPAN.
3172 The F<Changes> file for an explanation of how to view exhaustive details
3175 The F<INSTALL> file for how to build Perl.
3177 The F<README> file for general stuff.
3179 The F<Artistic> and F<Copying> files for copyright information.
3181 L<http://dev.perl.org/perl5/errata.html> for a list of issues
3182 found after this release, as well as a list of CPAN modules known
3183 to be incompatible with this release.