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 Perl now defaults to issuing a warning if a deprecated language feature
247 To disable this feature in a given lexical scope, you should use C<no
248 warnings 'deprecated';> For information about which language features
249 are deprecated and explanations of various deprecation warnings, please
250 see L<perldiag.pod>. See L</Deprecations> below for the list of features
251 and modules Perl's developers have deprecated as part of this release.
253 =head2 Version number formats
255 Acceptable version number formats have been formalized into "strict" and
256 "lax" rules. C<package NAME VERSION> takes a strict version number.
257 C<UNIVERSAL::VERSION> and the L<version> object constructors take lax
258 version numbers. Providing an invalid version will result in a fatal
259 error. The version argument in C<use NAME VERSION> is first parsed as a
260 numeric literal or v-string and then passed to C<UNIVERSAL::VERSION>
261 (and must then pass the "lax" format test).
263 These formats are documented fully in the L<version> module. To a first
264 approximation, a "strict" version number is a positive decimal number
265 (integer or decimal-fraction) without exponentiation or else a
266 dotted-decimal v-string with a leading 'v' character and at least three
267 components. A "lax" version number allows v-strings with fewer than
268 three components or without a leading 'v'. Under "lax" rules, both
269 decimal and dotted-decimal versions may have a trailing "alpha"
270 component separated by an underscore character after a fractional or
271 dotted-decimal component.
273 The L<version> module adds C<version::is_strict> and C<version::is_lax>
274 functions to check a scalar against these rules.
276 =head2 @INC reorganization
278 In C<@INC>, C<ARCHLIB> and C<PRIVLIB> now occur after after the current
279 version's C<site_perl> and C<vendor_perl>. Modules installed into
280 C<site_perl> and C<vendor_perl> will now be loaded in preference to
281 those installed in C<ARCHLIB> and C<PRIVLIB>.
283 =head2 Switch statement changes
285 The C<given>/C<when> switch statement handles complex statements better
286 than Perl 5.10.0 did (These enhancements are also available in
287 5.10.1 and subsequent 5.10 releases.) There are two new cases where
288 C<when> now interprets its argument as a boolean, instead of an
289 expression to be used in a smart match:
293 =item flip-flop operators
295 The C<..> and C<...> flip-flop operators are now evaluated in boolean
296 context, following their usual semantics; see L<perlop/"Range Operators">.
298 Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
299 whether a given value is an integer between 1 and 10; you should use
300 C<when ([1..10])> instead (note the array reference).
302 However, contrary to 5.10.0, evaluating the flip-flop operators in
303 boolean context ensures it can now be useful in a C<when()>, notably
304 for implementing bistable conditions, like in:
306 when (/^=begin/ .. /^=end/) {
310 =item defined-or operator
312 A compound expression involving the defined-or operator, as in
313 C<when (expr1 // expr2)>, will be treated as boolean if the first
314 expression is boolean. (This just extends the existing rule that applies
315 to the regular or operator, as in C<when (expr1 || expr2)>.)
319 =head2 Smart match changes
321 Since Perl 5.10.0, Perl's developers have made a number of changes to
322 the smart match operator. These, of course, also alter the behaviour
323 of the switch statements where smart matching is implicitly used.
324 These changes were also made for the 5.10.1 release, and will remain in
325 subsequent 5.10 releases.
327 =head3 Changes to type-based dispatch
329 The smart match operator C<~~> is no longer commutative. The behaviour of
330 a smart match now depends primarily on the type of its right hand
331 argument. Moreover, its semantics have been adjusted for greater
332 consistency or usefulness in several cases. While the general backwards
333 compatibility is maintained, several changes must be noted:
339 Code references with an empty prototype are no longer treated specially.
340 They are passed an argument like the other code references (even if they
341 choose to ignore it).
345 C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
346 returns a true value for each key of the hash (or element of the
347 array), instead of passing the whole hash or array as a reference to
352 Due to the commutativity breakage, code references are no longer
353 treated specially when appearing on the left of the C<~~> operator,
354 but like any vulgar scalar.
358 C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
359 hash). No implicit conversion to C<""> is done (as was the case in perl
364 C<$scalar ~~ @array> now always distributes the smart match across the
365 elements of the array. It's true if one element in @array verifies
366 C<$scalar ~~ $element>. This is a generalization of the old behaviour
367 that tested whether the array contained the scalar.
371 The full dispatch table for the smart match operator is given in
372 L<perlsyn/"Smart matching in detail">.
374 =head3 Smart match and overloading
376 According to the rule of dispatch based on the rightmost argument type,
377 when an object overloading C<~~> appears on the right side of the
378 operator, the overload routine will always be called (with a 3rd argument
379 set to a true value, see L<overload>.) However, when the object will
380 appear on the left, the overload routine will be called only when the
381 rightmost argument is a simple scalar. This way, distributivity of smart
382 match across arrays is not broken, as well as the other behaviours with
383 complex types (coderefs, hashes, regexes). Thus, writers of overloading
384 routines for smart match mostly need to worry only with comparing
385 against a scalar, and possibly with stringification overloading; the
386 other common cases will be automatically handled consistently.
388 C<~~> will now refuse to work on objects that do not overload it (in order
389 to avoid relying on the object's underlying structure). (However, if the
390 object overloads the stringification or the numification operators, and
391 if overload fallback is active, it will be used instead, as usual.)
393 =head2 Other potentially incompatible changes
399 The definitions of a number of Unicode properties have changed to match
400 those of the current Unicode standard. These are listed above under
401 L</Unicode overhaul>. This change may break code that expects the old
406 The boolkeys op has moved to the group of hash ops. This breaks binary
411 Filehandles are now always blessed into C<IO::File>.
413 The previous behaviour was to bless Filehandles into L<FileHandle>
414 (an empty proxy class) if it was loaded into memory and otherwise
415 to bless them into C<IO::Handle>.
419 The semantics of C<use feature :5.10*> have changed slightly.
420 See L<"Modules and Pragmata"> for more information.
424 Perl's developers now use git, rather than Perforce. This should be
425 a purely internal change only relevant to people actively working on
426 the core. However, you may see minor difference in perl as a consequence
427 of the change. For example in some of details of the output of C<perl
428 -V>. See L<perlrepository> for more information.
432 As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
433 C<Test::Harness::Straps> module has been removed.
434 See L</"Modules and Pragmata"> for more details.
438 As part of the C<ExtUtils::MakeMaker> upgrade, the
439 C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
440 have been removed from this distribution.
444 C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
449 C<length undef> now returns undef.
453 Unsupported private C API functions are now declared "static" to prevent
454 leakage to Perl's public API.
458 To support the bootstrapping process, F<miniperl> no longer builds with
459 UTF-8 support in the regexp engine.
461 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
462 Without this there's a bootstrapping problem, as miniperl can't load
463 the UTF-8 components of the regexp engine, because they're not yet built.
467 F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
468 C<$ENV{PERL5LIB}>, and "C<.>"
472 A space or a newline is now required after a C<"#line XXX"> directive.
476 Tied filehandles now have an additional method EOF which provides the
481 To better match all other flow control statements, C<foreach> may no
482 longer be used as an attribute.
489 From time to time, Perl's developers find it necessary to deprecate
490 features or modules we've previously shipped as part of the core
491 distribution. We are well aware of the pain and frustration that a
492 backwards-incompatible change to Perl can cause for developers building
493 or maintaining software in Perl. You can be sure that when we deprecate
494 a functionality or syntax, it isn't a choice we make lightly. Sometimes,
495 we choose to deprecate functionality or syntax because it was found to
496 be poorly designed or implemented. Sometimes, this is because they're
497 holding back other features or causing performance problems. Sometimes,
498 the reasons are more complex. Wherever possible, we try to keep deprecated
499 functionality available to developers in its previous form for at least
500 one major release. So long as a deprecated feature isn't actively
501 disrupting our ability to maintain and extend Perl, we'll try to leave
502 it in place as long as possible.
504 The following items are now deprecated:
510 C<suidperl> is no longer part of Perl. It used to provide a mechanism to
511 emulate setuid permission bits on systems that don't support it properly.
514 =item Use of C<:=> to mean an empty attribute list
516 An accident of Perl's parser meant that these constructions were all
523 with the C<:> being treated as the start of an attribute list, which
524 ends before the C<=>. As whitespace is not significant here, all are
525 parsed as an empty attribute list, hence all the above are equivalent
526 to, and better written as
530 because no attribute processing is done for an empty list.
532 As is, this meant that C<:=> cannot be used as a new token, without
533 silently changing the meaning of existing code. Hence that particular
534 form is now deprecated, and will become a syntax error. If it is
535 absolutely necessary to have empty attribute lists (for example,
536 because of a code generator) then avoid the warning by adding a space
539 =item C<< UNIVERSAL->import() >>
541 The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
542 pass import arguments to a C<use UNIVERSAL> statement will result in a
546 =item Use of "goto" to jump into a construct
548 Using C<goto> to jump from an outer scope into an inner scope is now
549 deprecated. This rare use case was causing problems in the
550 implementation of scopes.
552 =item Custom character names in \N{name} that don't look like names
554 In C<\N{I<name>}>, I<name> can be just about anything. The standard
555 Unicode names have a very limited domain, but a custom name translator
556 could create names that are, for example, made up entirely of punctuation
557 symbols. It is now deprecated to make names that don't begin with an
558 alphabetic character, and aren't alphanumeric or contain other than
559 a very few other characters, namely spaces, dashes, parentheses
560 and colons. Because of the added meaning of C<\N> (See L</C<\N>
561 experimental regex escape>), names that look like curly brace -enclosed
562 quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
563 4 non-newlines; before a custom name C<3,4> could have been created.
565 =item Deprecated Modules
567 The following modules will be removed from the core distribution in a
568 future release, and should be installed from CPAN instead. Distributions
569 on CPAN which require these should add them to their prerequisites. The
570 core versions of these modules warnings will issue a deprecation warning.
572 If you ship a packaged version of Perl, either alone or as part of a
573 larger system, then you should carefully consider the reprecussions of
574 core module deprecations. You may want to consider shipping your default
575 build of Perl with packages for some or all deprecated modules which
576 install into C<vendor> or C<site> perl library directories. This will
577 inhibit the deprecation warnings.
579 Alternatively, you may want to consider patching F<lib/deprecate.pm>
580 to provide deprecation warnings specific to your packaging system
581 or distribution of Perl, consistent with how your packaging system
582 or distribution manages a staged transition from a release where the
583 installation of a single package provides the given functionality, to
584 a later release where the system administrator needs to know to install
585 multiple packages to get that same functionality.
591 =item L<Pod::Plainer>
597 Switch is buggy and should be avoided. You may find Perl's new
598 C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
599 statements"> for more information.
603 =item Assignment to $[
605 =item Use of the attribute :locked on subroutines
607 =item Use of "locked" with the attributes pragma
609 =item Use of "unique" with the attributes pragma
613 C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
614 generates a deprecation warning, and it will be removed in a future
615 release. Although listed as part of the API, it was never documented,
616 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
617 core, it has been replaced by a static function.
619 =item Numerous Perl 4-era libraries
621 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
622 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
623 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
624 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
625 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
626 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
627 F<timelocal.pl> are all now deprecated. Using them will incur a warning.
632 =head1 Unicode overhaul
634 Perl's developers have made a concerted effort to update Perl to be in
635 sync with the latest Unicode standard. Changes for this include:
637 Perl can now handle every Unicode character property. New documentation,
638 L<perluniprops>, lists all available non-Unihan character properties. By
639 default, perl does not expose Unihan, deprecated or Unicode-internal
640 properties. See below for more details on these; there is also a section
641 in the pod listing them, and explaining why they are not exposed.
643 Perl now fully supports the Unicode compound-style of using C<=>
644 and C<:> in writing regular expressions: C<\p{property=value}> and
645 C<\p{property:value}> (both of which mean the same thing).
647 Perl now fully supports the Unicode loose matching rules for text between
648 the braces in C<\p{...}> constructs. In addition, Perl allows underscores
649 between digits of numbers.
651 Perl now accepts all the Unicode-defined synonyms for properties and
654 C<qr/\X/>, which matches a Unicode logical character, has
655 been expanded to work better with various Asian languages. It
656 now is defined as an I<extended grapheme cluster>. (See
657 L<http://www.unicode.org/reports/tr29/>). Anything matched previously
658 and that made sense will continue to be accepted. Additionally:
664 C<\X> will not break apart a C<S<CR LF>> sequence.
668 C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
673 C<\X> will now always match at least one character, including an initial
674 mark. Marks generally come after a base character, but it is possible in
675 Unicode to have them in isolation, and C<\X> will now handle that case,
676 for example at the beginning of a line, or after a C<ZWSP>. And this is
677 the part where C<\X> doesn't match the things that it used to that don't
678 make sense. Formerly, for example, you could have the nonsensical case
683 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
684 and Lao exception cases.
688 Otherwise, this change should be transparent for the non-affected
691 C<\p{...}> matches using the Canonical_Combining_Class property were
692 completely broken in previous releases of Perl. They should now work
695 Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
696 and a Perl extension had the same name, which led to neither matching
697 all the correct values (with more than 100 mistakes in one, and several
698 thousand in the other). The Perl extension has now been renamed to be
699 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
700 same meaning as was previously intended, namely the union of all the
701 non-canonical Decomposition types, with Unicode C<Compat> being just
704 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
706 C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
707 says they should. This means they each match a few more characters than
710 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
711 means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
712 nor Format (gc=cf) code points. The Format code points represent the
713 biggest possible problem. All but 36 of them are either officially
714 deprecated or strongly discouraged from being used. Of those 36, likely
715 the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
716 WJ, and similar characters, plus bidirectional controls.
718 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
719 5.12, Perl's definition definition included a number of things that aren't
720 really alpha (all marks) while omitting many that were. The definitions
721 of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
724 C<\p{Word}> no longer incorrectly matches non-word characters such
727 C<\p{Print}> no longer matches the line control characters: Tab, LF,
728 CR, FF, VT, and NEL. This brings it in line with standards and the
731 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
732 means that in addition to the characters it currently matches,
733 C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
734 example U+FF10: FULLWIDTH DIGIT ZERO.
736 The Numeric type property has been extended to include the Unihan
739 There is a new Perl extension, the 'Present_In', or simply 'In',
740 property. This is an extension of the Unicode Age property, but
741 C<\p{In=5.0}> matches any code point whose usage has been determined
742 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
743 added in I<precisely> version 5.0.
745 A number of properties now have the correct values for unassigned
746 code points. The affected properties are Bidi_Class, East_Asian_Width,
747 Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
750 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
751 are now up to date with current Unicode definitions.
753 Earlier versions of Perl erroneously exposed certain properties that
754 are supposed to be Unicode internal-only. Use of these in regular
755 expressions will now generate, if enabled, a deprecation warning message.
756 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
757 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
758 Other_Math, and Other_Uppercase.
760 It is now possible to change which Unicode properties Perl understands
761 on a per-installation basis. As mentioned above, certain properties
762 are turned off by default. These include all the Unihan properties
763 (which should be accessible via the CPAN module Unicode::Unihan) and any
764 deprecated or Unicode internal-only property that Perl has never exposed.
766 The generated files in the C<lib/unicore/To> directory are now more
767 clearly marked as being stable, directly usable by applications. New hash
768 entries in them give the format of the normal entries, which allows for
769 easier machine parsing. Perl can generate files in this directory for
770 any property, though most are suppressed. You can find instructions
771 for changing which are written in L<perluniprops>.
773 =head1 Modules and Pragmata
775 =head2 New Modules and Pragmata
781 C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
782 The bundled version is 2.06_01. Note that in this release, using a string
783 eval when C<autodie> is in effect can cause the autodie behaviour to leak
784 into the surrounding scope. See L<autodie/"BUGS"> for more details.
786 Version 2.06_01 has been added to the Perl core.
788 =item C<Compress::Raw::Bzip2>
790 Version 2.024 has been added to the Perl core.
794 C<overloading> allows you to lexically disable or enable overloading
795 for some or all operations.
797 Version 0.001 has been added to the Perl core.
801 C<parent> establishes an ISA relationship with base classes at compile
802 time. It provides the key feature of C<base> without further unwanted
805 Version 0.223 has been added to the Perl core.
807 =item C<Parse::CPAN::Meta>
809 Version 1.40 has been added to the Perl core.
813 Version 1.03 has been added to the Perl core.
817 Version 2.4 has been added to the Perl core.
819 =item C<XS::APItest::KeywordRPN>
821 Version 0.003 has been added to the Perl core.
825 =head2 Updated Pragmata
831 Upgraded from version 2.13 to 2.15.
835 Upgraded from version 0.22 to 0.23.
839 C<charnames> now contains the Unicode F<NameAliases.txt> database file.
840 This has the effect of adding some extra C<\N> character names that
841 formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
844 Upgraded from version 1.06 to 1.07.
848 Upgraded from version 1.13 to 1.20.
852 C<diagnostics> now supports %.0f formatting internally.
854 C<diagnostics> no longer suppresses C<Use of uninitialized value in range
855 (or flip)> warnings. [perl #71204]
857 Upgraded from version 1.17 to 1.19.
861 In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
862 bundles has changed slightly. The last component, if any (i.e. C<X>) is
863 simply ignored. This is predicated on the assumption that new features
864 will not, in general, be added to maintenance releases. So C<:5.10>
865 and C<:5.10.X> have identical effect. This is a change to the behaviour
866 documented for 5.10.0.
868 C<feature> now includes the C<unicode_strings> feature:
870 use feature "unicode_strings";
872 This pragma turns on Unicode semantics for the case-changing operations
873 (C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
874 internal UTF-8 flag set, but that contain single-byte characters between
877 Upgraded from version 1.11 to 1.16.
881 C<less> now includes the C<stash_name> method to allow subclasses of
882 C<less> to pick where in %^H to store their stash.
884 Upgraded from version 0.02 to 0.03.
888 Upgraded from version 0.5565 to 0.62.
892 C<mro> is now implemented as an XS extension. The documented interface has
893 not changed. Code relying on the implementation detail that some C<mro::>
894 methods happened to be available at all times gets to "keep both pieces".
896 Upgraded from version 1.00 to 1.02.
900 C<overload> now allow overloading of 'qr'.
902 Upgraded from version 1.06 to 1.10.
906 Upgraded from version 1.67 to 1.75.
908 =item C<threads::shared>
910 Upgraded from version 1.14 to 1.32.
914 C<version> now has support for L</Version number formats> as described
915 earlier in this document and in its own documentation.
917 Upgraded from version 0.74 to 0.82.
921 C<warnings> has a new C<warnings::fatal_enabled()> function. It also
922 includes a new C<illegalproto> warning category. See also L</New or
923 Changed Diagnostics> for this change.
925 Upgraded from version 1.06 to 1.09.
929 =head2 Updated Modules
933 =item C<Archive::Extract>
935 Upgraded from version 0.24 to 0.38.
937 =item C<Archive::Tar>
939 Upgraded from version 1.38 to 1.54.
941 =item C<Attribute::Handlers>
943 Upgraded from version 0.79 to 0.87.
947 Upgraded from version 5.63 to 5.70.
951 Upgraded from version 0.74 to 0.78.
955 Upgraded from version 1.05 to 1.12.
959 Upgraded from version 0.83 to 0.96.
963 Upgraded from version 1.09 to 1.11_01.
967 Upgraded from version 3.29 to 3.48.
971 Upgraded from version 0.33 to 0.36.
973 NOTE: C<Class::ISA> is deprecated and may be removed from a future
976 =item C<Compress::Raw::Zlib>
978 Upgraded from version 2.008 to 2.024.
982 Upgraded from version 1.9205 to 1.94_56.
986 Upgraded from version 0.84 to 0.90.
988 =item C<CPANPLUS::Dist::Build>
990 Upgraded from version 0.06_02 to 0.46.
992 =item C<Data::Dumper>
994 Upgraded from version 2.121_14 to 2.125.
998 Upgraded from version 1.816_1 to 1.820.
1000 =item C<Devel::PPPort>
1002 Upgraded from version 3.13 to 3.19.
1006 Upgraded from version 1.15 to 1.16.
1008 =item C<Digest::MD5>
1010 Upgraded from version 2.36_01 to 2.39.
1012 =item C<Digest::SHA>
1014 Upgraded from version 5.45 to 5.47.
1018 Upgraded from version 2.23 to 2.39.
1022 Upgraded from version 5.62 to 5.64_01.
1024 =item C<ExtUtils::CBuilder>
1026 Upgraded from version 0.21 to 0.27.
1028 =item C<ExtUtils::Command>
1030 Upgraded from version 1.13 to 1.16.
1032 =item C<ExtUtils::Constant>
1034 Upgraded from version 0.2 to 0.22.
1036 =item C<ExtUtils::Install>
1038 Upgraded from version 1.44 to 1.55.
1040 =item C<ExtUtils::MakeMaker>
1042 Upgraded from version 6.42 to 6.56.
1044 =item C<ExtUtils::Manifest>
1046 Upgraded from version 1.51_01 to 1.57.
1048 =item C<ExtUtils::ParseXS>
1050 Upgraded from version 2.18_02 to 2.21.
1052 =item C<File::Fetch>
1054 Upgraded from version 0.14 to 0.24.
1058 Upgraded from version 2.04 to 2.08_01.
1062 Upgraded from version 0.18 to 0.22.
1064 =item C<Filter::Simple>
1066 Upgraded from version 0.82 to 0.84.
1068 =item C<Filter::Util::Call>
1070 Upgraded from version 1.07 to 1.08.
1072 =item C<Getopt::Long>
1074 Upgraded from version 2.37 to 2.38.
1078 Upgraded from version 1.23_01 to 1.25_02.
1082 Upgraded from version 1.07 to 1.10.
1086 Upgraded from version 0.40_1 to 0.54.
1090 Upgraded from version 1.05 to 2.01.
1092 =item C<Locale::Maketext>
1094 Upgraded from version 1.12 to 1.14.
1096 =item C<Locale::Maketext::Simple>
1098 Upgraded from version 0.18 to 0.21.
1100 =item C<Log::Message>
1102 Upgraded from version 0.01 to 0.02.
1104 =item C<Log::Message::Simple>
1106 Upgraded from version 0.04 to 0.06.
1108 =item C<Math::BigInt>
1110 Upgraded from version 1.88 to 1.89_01.
1112 =item C<Math::BigInt::FastCalc>
1114 Upgraded from version 0.16 to 0.19.
1116 =item C<Math::BigRat>
1118 Upgraded from version 0.21 to 0.24.
1120 =item C<Math::Complex>
1122 Upgraded from version 1.37 to 1.56.
1126 Upgraded from version 1.01_02 to 1.01_03.
1128 =item C<MIME::Base64>
1130 Upgraded from version 3.07_01 to 3.08.
1132 =item C<Module::Build>
1134 Upgraded from version 0.2808_01 to 0.3603.
1136 =item C<Module::CoreList>
1138 Upgraded from version 2.12 to 2.29.
1140 =item C<Module::Load>
1142 Upgraded from version 0.12 to 0.16.
1144 =item C<Module::Load::Conditional>
1146 Upgraded from version 0.22 to 0.34.
1148 =item C<Module::Loaded>
1150 Upgraded from version 0.01 to 0.06.
1152 =item C<Module::Pluggable>
1154 Upgraded from version 3.6 to 3.9.
1158 Upgraded from version 2.33 to 2.36.
1162 Upgraded from version 0.60_01 to 0.64.
1164 =item C<Object::Accessor>
1166 Upgraded from version 0.32 to 0.36.
1168 =item C<Package::Constants>
1170 Upgraded from version 0.01 to 0.02.
1174 Upgraded from version 1.04 to 1.06.
1176 =item C<Pod::Parser>
1178 Upgraded from version 1.35 to 1.37.
1180 =item C<Pod::Perldoc>
1182 Upgraded from version 3.14_02 to 3.15_02.
1184 =item C<Pod::Plainer>
1186 Upgraded from version 0.01 to 1.02.
1188 NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
1191 =item C<Pod::Simple>
1193 Upgraded from version 3.05 to 3.13.
1197 Upgraded from version 2.12 to 2.22.
1201 Upgraded from version 1.11 to 1.17.
1205 Upgraded from version 2.18 to 2.22.
1209 Upgraded from version 2.13 to 2.16.
1211 NOTE: C<Switch> is deprecated and may be removed from a future version
1214 =item C<Sys::Syslog>
1216 Upgraded from version 0.22 to 0.27.
1218 =item C<Term::ANSIColor>
1220 Upgraded from version 1.12 to 2.02.
1224 Upgraded from version 0.18 to 0.20.
1228 Upgraded from version 1.25 to 1.25_02.
1230 =item C<Test::Harness>
1232 Upgraded from version 2.64 to 3.17.
1234 =item C<Test::Simple>
1236 Upgraded from version 0.72 to 0.94.
1238 =item C<Text::Balanced>
1240 Upgraded from version 2.0.0 to 2.02.
1242 =item C<Text::ParseWords>
1244 Upgraded from version 3.26 to 3.27.
1246 =item C<Text::Soundex>
1248 Upgraded from version 3.03 to 3.03_01.
1250 =item C<Thread::Queue>
1252 Upgraded from version 2.00 to 2.11.
1254 =item C<Thread::Semaphore>
1256 Upgraded from version 2.01 to 2.09.
1258 =item C<Tie::RefHash>
1260 Upgraded from version 1.37 to 1.38.
1262 =item C<Time::HiRes>
1264 Upgraded from version 1.9711 to 1.9719.
1266 =item C<Time::Local>
1268 Upgraded from version 1.18 to 1.1901_01.
1270 =item C<Time::Piece>
1272 Upgraded from version 1.12 to 1.15.
1274 =item C<Unicode::Collate>
1276 Upgraded from version 0.52 to 0.52_01.
1278 =item C<Unicode::Normalize>
1280 Upgraded from version 1.02 to 1.03.
1284 Upgraded from version 0.34 to 0.39.
1286 =item C<Win32API::File>
1288 Upgraded from version 0.1001_01 to 0.1101.
1292 Upgraded from version 0.08 to 0.10.
1296 =head2 Removed Modules and Pragmata
1302 Removed from the Perl core. Prior version was 1.02.
1304 =item C<CPAN::API::HOWTO>
1306 Removed from the Perl core. Prior version was 'undef'.
1308 =item C<CPAN::DeferedCode>
1310 Removed from the Perl core. Prior version was 5.50.
1312 =item C<CPANPLUS::inc>
1314 Removed from the Perl core. Prior version was 'undef'.
1318 Removed from the Perl core. Prior version was 1.03.
1320 =item C<ExtUtils::MakeMaker::bytes>
1322 Removed from the Perl core. Prior version was 6.42.
1324 =item C<ExtUtils::MakeMaker::vmsish>
1326 Removed from the Perl core. Prior version was 6.42.
1330 Removed from the Perl core. Prior version was 2.3.
1332 =item C<Test::Harness::Assert>
1334 Removed from the Perl core. Prior version was 0.02.
1336 =item C<Test::Harness::Iterator>
1338 Removed from the Perl core. Prior version was 0.02.
1340 =item C<Test::Harness::Point>
1342 Removed from the Perl core. Prior version was 0.01.
1344 =item C<Test::Harness::Results>
1346 Removed from the Perl core. Prior version was 0.01.
1348 =item C<Test::Harness::Straps>
1350 Removed from the Perl core. Prior version was 0.26_01.
1352 =item C<Test::Harness::Util>
1354 Removed from the Perl core. Prior version was 0.01.
1358 Removed from the Perl core. Prior version was 1.1.
1362 =head2 Deprecated Modules and Pragmata
1364 See L</Deprecated Modules> above.
1367 =head1 Documentation
1369 =head2 New Documentation
1375 L<perlhaiku> contains instructions on how to build perl for the Haiku
1380 L<perlmroapi> describes the new interface for pluggable Method Resolution
1385 L<perlperf>, by Richard Foley, provides an introduction to the use of
1386 performance and optimization techniques which can be used with particular
1387 reference to perl programs.
1391 L<perlrepository> describes how to access the perl source using the I<git>
1392 version control system.
1396 L<perlpolicy> extends the "Social contract about contributed modules" into
1397 the beginnings of a document on Perl porting policies.
1401 =head2 Changes to Existing Documentation
1409 The various large F<Changes*> files (which listed every change made
1410 to perl over the last 18 years) have been removed, and replaced by a
1411 small file, also called F<Changes>, which just explains how that same
1412 information may be extracted from the git version control system.
1416 F<Porting/patching.pod> has been deleted, as it mainly described
1417 interacting with the old Perforce-based repository, which is now obsolete.
1418 Information still relevant has been moved to L<perlrepository>.
1423 The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
1424 as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
1425 BLOCK>, although actually using the latter may not be the best idea for
1426 the readability of your source code.
1431 Documented -X overloading.
1435 Documented that C<when()> treats specially most of the filetest operators
1439 Documented C<when> as a syntax modifier.
1443 Eliminated "Old Perl threads tutorial", which described 5005 threads.
1445 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1449 Correct previous documentation: v-strings are not deprecated
1451 With version objects, we need them to use MODULE VERSION syntax. This
1452 patch removes the deprecation notice.
1456 Security contact information is now part of L<perlsec>.
1460 A significant fraction of the core documentation has been updated to
1461 clarify the behavior of Perl's Unicode handling.
1463 Much of the remaining core documentation has been reviewed and edited
1464 for clarity, consistent use of language, and to fix the spelling of Tom
1465 Christiansen's name.
1469 The Pod specification (L<perlpodspec>) has been updated to bring the
1470 specification in line with modern usage already supported by most Pod
1471 systems. A parameter string may now follow the format name in a
1472 "begin/end" region. Links to URIs with a text description are now
1473 allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
1478 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1479 conditional loading of modules despite the implicit BEGIN block around
1484 The documentation for C<$1> in perlvar.pod has been clarified.
1488 C<\N{U+I<wide hex char>}> is now documented.
1492 =head1 Selected Performance Enhancements
1498 A new internal cache means that C<isa()> will often be faster.
1502 The implementation of C<C3> Method Resolution Order has been
1503 optimised - linearisation for classes with single inheritance is 40%
1504 faster. Performance for multiple inheritance is unchanged.
1508 Under C<use locale>, the locale-relevant information is now cached on
1509 read-only values, such as the list returned by C<keys %hash>. This makes
1510 operations such as C<sort keys %hash> in the scope of C<use locale>
1515 Empty C<DESTROY> methods are no longer called.
1519 C<Perl_sv_utf8_upgrade()> is now faster.
1523 C<keys> on empty hash is now faster.
1527 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
1531 The string repetition operator (C<$str x $num>) is now several times
1532 faster when C<$str> has length one or C<$num> is large.
1536 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1537 now happens in-place and is several orders of magnitude faster than
1538 it used to be. It will also preserve non-existent elements whenever
1539 possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
1540 and C<DELETE> methods.
1544 =head1 Installation and Configuration Improvements
1550 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
1551 generated at build time, rather than being shipped as part of the release.
1555 If C<vendorlib> and C<vendorarch> are the same, then they are only added
1560 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1561 perl is built with C<-Dusedevel>.
1565 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1566 against stack-smashing attacks, if the compiler supports it.
1570 F<Configure> will now determine the correct prototypes for re-entrant
1571 functions and for C<gconvert> if you are using a C++ compiler rather
1576 On Unix, if you build from a tree containing a git repository, the
1577 configuration process will note the commit hash you have checked out, for
1578 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1579 are automatically added to the list of local patches displayed by
1584 Perl now supports SystemTap's C<dtrace> compatibility layer and an
1585 issue with linking C<miniperl> has been fixed in the process.
1589 perldoc now uses C<less -R> instead of C<less> for improved behaviour
1590 in the face of C<groff>'s new usage of ANSI escape codes.
1595 C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
1596 C<USE_ATTRIBUTES_FOR_PERLIO>.
1600 As part of the flattening of F<ext>, all extensions on all platforms are
1601 built by F<make_ext.pl>. This replaces the Unix-specific
1602 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1603 F<win32/buildext.pl>.
1607 =head1 Internal Changes
1609 Each release of Perl sees numerous internal changes which shouldn't
1610 affect day to day usage but may still be notable for developers working
1611 with Perl's source code.
1617 The J.R.R. Tolkien quotes at the head of C source file have been checked
1618 and proper citations added, thanks to a patch from Tom Christiansen.
1622 The internal structure of the dual-life modules traditionally found in
1623 the F<lib/> and F<ext/> directories y in the perl source has changed
1624 significantly. Where possible, dual-lifed modules have been extracted
1625 from F<lib/> and F<ext/>.
1627 Dual-lifed modules maintained by Perl's developers as part of the Perl
1628 core now live in F<dist/>. Dual-lifed modules maintained primarily on
1629 CPAN now live in F<cpan/>. When reporting a bug in a module located
1630 under F<cpan/>, please send your bug report directly to the module's
1631 bug tracker or author, rather than Perl's bug tracker.
1635 C<\N{...}> now compiles better, always forces UTF-8 internal representation
1637 Perl's developers have fixed several problems with the recognition of
1638 C<\N{...}> constructs. As part of this, perl will store any scalar
1639 or regex containing C<\N{I<name>}> or C<\N{U+I<wide hex char>}> in its
1640 definition in UTF-8 format. (This was true previously for all occurences
1641 of C<\N{I<name>}> that did not use a custom translator, but now it's
1646 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1650 C<SVt_RV> no longer exists. RVs are now stored in IVs.
1654 REGEXPs are now first class.
1658 C<Perl_vcroak()> now accepts a null first argument. In addition, a full
1659 audit was made of the "not NULL" compiler annotations, and those for
1660 several other internal functions were corrected.
1664 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1665 have been added to formalise the temporary saving of the C<errno>
1670 The function C<Perl_sv_insert_flags> has been added to augment
1675 The function C<Perl_newSV_type(type)> has been added, equivalent to
1676 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1680 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1681 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1683 Two flag bits are currently supported.
1689 C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
1690 not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
1691 C<newSVpvn_utf8()> is available for this.
1695 C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
1699 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1703 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1708 Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
1712 C<PL_na> has been exterminated from the core code, replaced by local
1713 STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
1714 C<PL_na>, which is a pointer dereference into the interpreter structure
1715 under ithreads, and a global variable otherwise.
1719 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
1720 on the scalar. It now updates the linked list to remove each piece of
1721 magic as it is freed.
1725 Under ithreads, the regex in C<PL_reg_curpm> is now reference
1726 counted. This eliminates a lot of hackish workarounds to cope with it
1727 not being reference counted.
1731 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1732 This has been fixed.
1736 The I<public> IV and NV flags are now not set if the string value has
1737 trailing "garbage". This behaviour is consistent with not setting the
1738 public IV or NV flags if the value is out of range for the type.
1742 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
1743 been replaced by C<NULL> in the core code, and non-dual-life modules,
1744 as C<NULL> is clearer to those unfamiliar with the core code.
1748 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1749 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1750 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1751 casting away C<const>. This allows proper compile-time auditing of
1752 C<const> correctness in the core, and helped picked up some errors
1757 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1758 stack and mortalizing them.
1762 Use of the private structure C<mro_meta> has changed slightly. Nothing
1763 outside the core should be accessing this directly anyway.
1767 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1768 to view how a C preprocessor macro would be expanded when compiled.
1769 This is handy when trying to decode the macro hell that is the perl
1776 =head2 Testing improvements
1780 =item Parallel tests
1782 The core distribution can now run its regression tests in parallel on
1783 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
1784 your environment to the number of tests to run in parallel, and run
1785 C<make test_harness>. On a Bourne-like shell, this can be done as
1787 TEST_JOBS=3 make test_harness # Run 3 tests in parallel
1789 An environment variable is used, rather than parallel make itself, because
1790 L<TAP::Harness> needs to be able to schedule individual non-conflicting test
1791 scripts itself, and there is no standard interface to C<make> utilities to
1792 interact with their job schedulers.
1794 Note that currently some test scripts may fail when run in parallel (most
1795 notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
1796 again sequentially and see if the failures go away.
1798 =item Test harness flexibility
1800 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1804 Several tests that have the potential to hang forever if they fail now
1805 incorporate a "watchdog" functionality that will kill them after a timeout,
1806 which helps ensure that C<make test> and C<make test_harness> run to
1807 completion automatically.
1814 Perl's developers have added a number of new tests to the core.
1815 In addition to the items listed below, many modules updated from CPAN
1816 incorporate new tests.
1822 Significant cleanups to core tests to ensure that language and
1823 interpreter features are not used before they're tested.
1827 C<make test_porting> now runs a number of important pre-commit checks
1828 which might be of use to anyone working on the Perl core.
1832 F<t/porting/podcheck.t> automatically checks the well-formedness of
1833 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1834 dual-lifed modules which are primarily maintained outside the Perl core.
1838 F<t/porting/manifest.t> now tests that all files listed in MANIFEST
1843 F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
1847 F<t/comp/retainedlines.t> checks that the debugger can retain source
1852 F<t/io/perlio_fail.t> checks that bad layers fail.
1856 F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
1860 F<t/io/perlio_open.t> checks that certain special forms of open work.
1864 F<t/io/perlio.t> includes general PerlIO tests.
1868 F<t/io/pvbm.t> checks that there is no unexpected interaction between
1869 the internal types C<PVBM> and C<PVGV>.
1873 F<t/mro/package_aliases.t> checks that mro works properly in the presence
1874 of aliased packages.
1878 F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
1882 F<t/op/index_thr.t> tests the interaction of C<index> and threads.
1886 F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
1890 F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
1894 F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
1898 F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
1899 embedded C<qr//> and threads.
1903 F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
1908 F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
1909 properties and threads.
1913 F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
1917 F<t/op/reg_posixcc.t> checks that POSIX character classes behave
1922 F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
1926 F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
1930 F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
1934 F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
1938 F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
1942 F<t/uni/tie.t> checks that Unicode and C<tie> work.
1946 F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
1950 F<t/comp/form_scope.t> tests format scoping.
1954 F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
1958 F<t/op/filetest_t.t> tests if -t file test works.
1962 F<t/op/qr.t> tests C<qr>.
1966 F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
1970 F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
1974 F<t/op/filehandle.t> tests some suitably portable filetest operators
1975 to check that they work as expected, particularly in the light of some
1976 internal changes made in how filehandles are blessed.
1980 F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
1981 can now be handed to C<gmtime> and C<localtime>, do not cause an internal
1982 overflow or an excessively long loop.
1987 =head1 New or Changed Diagnostics
1989 =head2 New Diagnostics
1995 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
1996 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
1997 that was enabled when the F<perl> binary was compiled.
2001 Smartmatch resolution tracing has been added as a new diagnostic. Use
2002 C<-DM> to enable it.
2006 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
2007 C<-Dx> for its original purpose of dumping syntax trees.
2011 Perl 5.12 provides a number of new diagnostic messages to help you write
2012 better code. See L<perldiag> for details of these new messages.
2018 C<Bad plugin affecting keyword '%s'>
2022 C<gmtime(%.0f) too large>
2026 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
2030 C<Lexing code internal error (%s)>
2034 C<localtime(%.0f) too large>
2038 C<Overloaded dereference did not return a reference>
2042 C<Overloaded qr did not return a REGEXP>
2046 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
2050 C<lvalue attribute ignored after the subroutine has been defined>
2052 This new warning is issued when one attempts to mark a subroutine as
2053 lvalue after it has been defined.
2057 Perl now warns you if C<++> or C<--> are unable to change the value
2058 because it's beyond the limit of representation.
2060 This uses a new warnings category: "imprecision".
2064 C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
2068 C<Show constant in "Useless use of a constant in void context">
2072 C<Prototype after '%s'>
2076 C<panic: sv_chop %s>
2078 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
2079 passed a position that is not within the scalar's string buffer. This
2080 could be caused by buggy XS code, and at this point recovery is not
2086 The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
2087 C<charnames> handler returns malformed UTF-8.
2091 If an unresolved named character or sequence was encountered when
2092 compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
2093 by the lexer> is now produced. This can happen, for example, when using a
2094 single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
2095 for more examples of how the lexer can get bypassed.
2099 C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
2100 triggered when the character constant represented by C<...> is not a
2101 valid hexadecimal number.
2105 The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
2106 class, just like C<.> in a character class loses its special meaning,
2107 and will cause the fatal error C<\N in a character class must be a named
2108 character: \N{...}>.
2112 The rules on what is legal for the C<...> in C<\N{...}> have been
2113 tightened up so that unless the C<...> begins with an alphabetic
2114 character and continues with a combination of alphanumerics, dashes,
2115 spaces, parentheses or colons then the warning C<Deprecated character(s)
2116 in \N{...} starting at '%s'> is now issued.
2120 The warning C<Using just the first characters returned by \N{}> will
2121 be issued if the C<charnames> handler returns a sequence of characters
2122 which exceeds the limit of the number of characters that can be used. The
2123 message will indicate which characters were used and which were discarded.
2129 =head2 Changed Diagnostics
2131 A number of existing diagnostic messages have been improved or corrected:
2137 A new warning category C<illegalproto> allows finer-grained control of
2138 warnings around function prototypes.
2144 =item C<Illegal character in prototype for %s : %s>
2146 =item C<Prototype after '%c' for %s : %s>
2150 have been moved from the C<syntax> top-level warnings category into a new
2151 first-level category, C<illegalproto>. These two warnings are currently
2152 the only ones emitted during parsing of an invalid/illegal prototype,
2155 no warnings 'illegalproto';
2157 to suppress only those, but not other syntax-related warnings. Warnings
2158 where prototypes are changed, ignored, or not met are still in the
2159 C<prototype> category as before.
2163 C<Deep recursion on subroutine "%s">
2165 It is now possible to change the depth threshold for this warning from the
2166 default of 100, by recompiling the F<perl> binary, setting the C
2167 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
2171 C<Illegal character in prototype> warning is now more precise
2172 when reporting illegal characters after _
2176 mro merging error messages are now very similar to those produced by
2181 Amelioration of the error message "Unrecognized character %s in column %d"
2183 Changes the error message to "Unrecognized character %s; marked by E<lt>--
2184 HERE after %sE<lt>-- HERE near column %d". This should make it a little
2185 simpler to spot and correct the suspicious character.
2189 Perl now explicitly points to C<$.> when it causes an uninitialized
2190 warning for ranges in scalar context.
2194 C<split> now warns when called in void context.
2198 C<printf>-style functions called with too few arguments will now issue the
2199 warning C<"Missing argument in %s"> [perl #71000]
2203 Perl now properly returns a syntax error instead of segfaulting
2204 if C<each>, C<keys>, or C<values> is used without an argument.
2208 C<tell()> now fails properly if called without an argument and when no
2209 previous file was read.
2211 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
2212 the 5.8.x behaviour.
2216 C<overload> no longer implicitly unsets fallback on repeated 'use
2221 POSIX::strftime() can now handle Unicode characters in the format string.
2225 The C<syntax> category was removed from 5 warnings that should only be in
2230 Three fatal C<pack>/C<unpack> error messages have been normalized to
2235 C<Unicode character is illegal> has been rephrased to be more accurate
2237 It now reads C<Unicode non-character is illegal in interchange> and the
2238 perldiag documentation has been expanded a bit.
2242 Currently, all but the first of the several characters that the
2243 C<charnames> handler may return are discarded when used in a regular
2244 expression pattern bracketed character class. If this happens then the
2245 warning C<Using just the first character returned by \N{} in character
2246 class> will be issued.
2250 The warning C<Missing right brace on \N{} or unescaped left brace after
2251 \N. Assuming the latter> will be issued if Perl encounters a C<\N{>
2252 but doesn't find a matching C<}>. In this case Perl doesn't know if it
2253 was mistakenly omitted, or if "match non-newline" followed by "match
2254 a C<{>" was desired. It assumes the latter because that is actually a
2255 valid interpretation as written, unlike the other case. If you meant
2256 the former, you need to add the matching right brace. If you did mean
2257 the latter, you can silence this warning by writing instead C<\N\{>.
2261 C<gmtime> and C<localtime> called with numbers smaller than they can
2262 reliably handle will now issue the warnings C<gmtime(%.0f) too small>
2263 and C<localtime(%.0f) too small>.
2267 The following diagnostic messages have been removed:
2277 C<Can't locate package %s for the parents of %s>
2279 In general this warning it only got produced in
2280 conjunction with other warnings, and removing it allowed an ISA lookup
2281 optimisation to be added.
2285 C<v-string in use/require is non-portable>
2289 =head1 Utility Changes
2295 F<h2ph> now looks in C<include-fixed> too, which is a recent addition
2296 to gcc's search path.
2300 F<h2xs> no longer incorrectly treats enum values like macros.
2301 It also now handles C++ style comments (C<//>) properly in enums.
2305 F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
2306 debugger now correctly handles proxy constant subroutines, and
2311 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
2312 upstream bug tracker URLs. If a user identifies a particular module
2313 as the topic of their bug report and we're able to divine the URL for
2314 its upstream bug tracker, perlbug now provide a message to the user
2315 explaining that the core copies the CPAN version directly, and provide
2316 the URL for reporting the bug directly to the upstream author.
2318 F<perlbug> no longer reports "Message sent" when it hasn't actually sent
2323 F<perlthanks> is a new utility for sending non-bug-reports to the
2324 authors and maintainers of Perl. Getting nothing but bug reports can
2325 become a bit demoralising. If Perl 5.12 works well for you, please try
2326 out F<perlthanks>. It will make the developers smile.
2330 Perl's developers have fixed bugs in F<a2p> having to do with the
2331 C<match()> operator in list context. Additionally, F<a2p> no longer
2332 generates code that uses the C<$[> variable.
2336 =head1 Selected Bug Fixes
2342 U+0FFFF is now a legal character in regular expressions.
2346 pp_qr now always returns a new regexp SV. Resolves RT #69852.
2348 Instead of returning a(nother) reference to the (pre-compiled) regexp
2349 in the optree, use reg_temp_copy() to create a copy of it, and return a
2350 reference to that. This resolves issues about Regexp::DESTROY not being
2351 called in a timely fashion (the original bug tracked by RT #69852), as
2352 well as bugs related to blessing regexps, and of assigning to regexps,
2353 as described in correspondence added to the ticket.
2355 It transpires that we also need to undo the SvPVX() sharing when ithreads
2356 cloning a Regexp SV, because mother_re is set to NULL, instead of a
2357 cloned copy of the mother_re. This change might fix bugs with regexps
2358 and threads in certain other situations, but as yet neither tests nor
2359 bug reports have indicated any problems, so it might not actually be an
2360 edge case that it's possible to reach.
2364 Several compilation errors and segfaults when perl was built with C<-Dmad>
2369 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
2373 C<-t> should only return TRUE for file handles connected to a TTY
2375 The Microsoft C version of C<isatty()> returns TRUE for all character mode
2376 devices, including the F</dev/null>-style "nul" device and printers like
2381 Fixed a regression caused by commit fafafbaf which caused a panic during
2382 parameter passing [perl #70171]
2386 On systems which in-place edits without backup files, -i'*' now works as
2387 the documentation says it does [perl #70802]
2391 Saving and restoring magic flags no longer loses readonly flag.
2395 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
2396 causes abrupt and total failure.
2400 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
2405 Using named subroutines with C<sort> should no longer lead to bus errors
2410 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
2414 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
2418 C<$@> may now be assigned a read-only value (without error or busting
2423 C<sort> called recursively from within an active comparison subroutine no
2424 longer causes a bus error if run multiple times. [perl #71076]
2428 Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
2432 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
2437 C<-I> on shebang line now adds directories in front of @INC
2438 as documented, and as does C<-I> when specified on the command-line.
2442 C<kill> is now fatal when called on non-numeric process identifiers.
2443 Previously, an C<undef> process identifier would be interpreted as a
2444 request to kill process 0, which would terminate the current process
2445 group on POSIX systems. Since process identifiers are always integers,
2446 killing a non-numeric process is now fatal.
2450 5.10.0 inadvertently disabled an optimisation, which caused a measurable
2451 performance drop in list assignment, such as is often used to assign
2452 function parameters from C<@_>. The optimisation has been re-instated, and
2453 the performance regression fixed. (This fix is also present in 5.10.1)
2457 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
2461 Some potential coredumps in PerlIO fixed [RT #57322,54828].
2465 The debugger now works with lvalue subroutines.
2469 The debugger's C<m> command was broken on modules that defined constants
2474 C<crypt> and string complement could return tainted values for untainted
2475 arguments [RT #59998].
2479 The C<-i>I<.suffix> command-line switch now recreates the file using
2480 restricted permissions, before changing its mode to match the original
2481 file. This eliminates a potential race condition [RT #60904].
2485 On some Unix systems, the value in C<$?> would not have the top bit set
2486 (C<$? & 128>) even if the child core dumped.
2490 Under some circumstances, C<$^R> could incorrectly become undefined
2495 In the XS API, various hash functions, when passed a pre-computed hash where
2496 the key is UTF-8, might result in an incorrect lookup.
2500 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2505 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
2506 didn't exist, even if the object's C<@ISA> contained C<Foo>.
2510 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2511 C<@ISA>, have been found and fixed.
2515 Bitwise operations on references could crash the interpreter, e.g.
2516 C<$x=\$y; $x |= "foo"> [RT #54956].
2520 Patterns including alternation might be sensitive to the internal UTF-8
2521 representation, e.g.
2523 my $byte = chr(192);
2524 my $utf8 = chr(192); utf8::upgrade($utf8);
2525 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2529 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2530 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2531 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2532 greater than 255 [RT #59908].
2536 C<B::Deparse> failed to correctly deparse various constructs:
2537 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2538 C<sub foo(_)> [RT #62484].
2542 Using C<setpgrp> with no arguments could corrupt the perl stack.
2546 The block form of C<eval> is now specifically trappable by C<Safe> and
2547 C<ops>. Previously it was erroneously treated like string C<eval>.
2551 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2552 match operator (C<~~>) [RT #63854].
2556 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2557 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2559 ("ab" x 32768) =~ /^(ab)*$/
2563 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2567 Using C<next> or C<last> to exit a C<given> block no longer produces a
2568 spurious warning like the following:
2570 Exiting given via last at foo.pl line 123
2574 Assigning a format to a glob could corrupt the format; e.g.:
2576 *bar=*foo{FORMAT}; # foo format now bad
2580 Attempting to coerce a typeglob to a string or number could cause an
2581 assertion failure. The correct error message is now generated,
2582 C<Can't coerce GLOB to I<$type>>.
2586 Under C<use filetest 'access'>, C<-x> was using the wrong access
2587 mode. This has been fixed [RT #49003].
2591 C<length> on a tied scalar that returned a Unicode value would not be
2592 correct the first time. This has been fixed.
2596 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2601 A race condition inside C<PerlIOStdio_close()> has been identified and
2602 fixed. This used to cause various threading issues, including SEGVs.
2606 In C<unpack>, the use of C<()> groups in scalar context was internally
2607 placing a list on the interpreter's stack, which manifested in various
2608 ways, including SEGVs. This is now fixed [RT #50256].
2612 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2613 These have all been fixed.
2617 A 5.10.0 optimisation to clear the temporary stack within the implicit
2618 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2619 obscure bugs in seemingly unrelated parts of the interpreter [commit
2624 The line numbers for warnings inside C<elsif> are now correct.
2628 The C<..> operator now works correctly with ranges whose ends are at or
2629 close to the values of the smallest and largest integers.
2633 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2634 This has been fixed [RT #54828].
2638 An off-by-one error meant that C<index $str, ...> was effectively being
2639 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2643 Various leaks associated with named captures in regexes have been fixed
2648 A weak reference to a hash would leak. This was affecting C<DBI>
2653 Using (?|) in a regex could cause a segfault [RT #59734].
2657 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2661 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2662 unaligned 64-bit access on the SPARC architecture [RT #60574].
2666 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2667 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2672 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2677 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2678 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2683 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2684 missed (method cache issue) [RT #60220,60232].
2688 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2689 cause a memory leak [RT #63110].
2693 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2694 specified on the command line. C<-C> on the shebang line used to be a
2695 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2696 disallowed it, which broke some scripts. Now perl checks whether it is
2697 also on the command line and only dies if it is not [RT #67880].
2701 In 5.10.0, certain types of re-entrant regular expression could crash,
2702 or cause the following assertion failure [RT #60508]:
2704 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2708 Perl now includes previously missing files from the Unicode Character
2713 Perl now honors C<TMPDIR> when opening an anonymous temporary file.
2718 =head1 Platform Specific Changes
2720 Perl is incredibly portable. In general, if a platform has a C compiler,
2721 someone has ported Perl to it (or will soon). We're happy to announce
2722 that Perl 5.12 includes support for several new platforms. At the same
2723 time, it's time to bid farewell to some (very) old friends.
2725 =head2 New Platforms
2731 Perl's developers have merged patches from Haiku's maintainers. Perl
2732 should now build on Haiku.
2736 Perl should now build on MirOS BSD.
2740 =head2 Discontinued Platforms
2752 =head2 Updated Platforms
2762 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
2767 Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
2768 installed. The F<libgdbm> is delivered as an optional package with the
2769 AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
2773 Hints changes mean that AIX 4.2 should work again.
2783 Perl now supports IPv6 on Cygwin 1.7 and newer.
2787 On Cygwin we now strip the last number from the DLL. This has been the
2788 behaviour in the cygwin.com build for years. The hints files have been
2793 =item Darwin (Mac OS X)
2799 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2800 as it's still buggy.
2804 Correct infelicities in the regexp used to identify buggy locales
2805 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2815 Fix thread library selection [perl #69686]
2825 The hints files now identify the correct threading libraries on FreeBSD 7
2836 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2837 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2847 Hints now supports versions 5.*.
2857 C<-UDEBUGGING> is now the default on VMS.
2859 Like it has been everywhere else for ages and ages. Also make command-line
2860 selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
2861 the only way to turn it off was by saying no in answer to the interactive
2866 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2871 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2872 if C<$/> was set to a numeric reference (to indicate record-style reads).
2877 VMS now supports C<getgrgid>.
2881 Many improvements and cleanups have been made to the VMS file name handling
2882 and conversion code.
2886 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2887 status in a VMS condition value for better interaction with GNV's bash
2888 shell and other utilities that depend on POSIX exit values. See
2889 L<perlvms/"$?"> for details.
2893 C<File::Copy> now detects Unix compatibility mode on VMS.
2903 Various changes from Stratus have been merged in.
2913 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2923 Perl 5.12 supports Windows 2000 and later. The supporting code for
2924 legacy versions of Windows is still included, but will be removed
2925 during the next development cycle.
2929 Initial support for building Perl with MinGW-w64 is now available.
2933 F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
2934 settings for Windows Vista and later. Without this setting Windows
2935 would treat F<perl.exe> as a legacy application and apply various
2936 heuristics like redirecting access to protected file system areas
2937 (like the "Program Files" folder) to the users "VirtualStore"
2938 instead of generating a proper "permission denied" error.
2940 The manifest resource also requests the Microsoft Common-Controls
2941 version 6.0 (themed controls introduced in Windows XP). Check out the
2942 Win32::VisualStyles module on CPAN to switch back to old style
2943 unthemed controls for legacy applications.
2947 The C<-t> filetest operator now only returns true if the filehandle
2948 is connected to a console window. In previous versions of Perl it
2949 would return true for all character mode devices, including F<NUL>
2954 The C<-p> filetest operator now works correctly, and the
2955 Fcntl::S_IFIFO constant is defined when Perl is compiled with
2956 Microsoft Visual C. In previous Perl versions C<-p> always
2957 returned a false value, and the Fcntl::S_IFIFO constant
2960 This bug is specific to Microsoft Visual C and never affected
2961 Perl binaries built with MinGW.
2965 The socket error codes are now more widely supported: The POSIX
2966 module will define the symbolic names, like POSIX::EWOULDBLOCK,
2967 and stringification of socket error codes in $! works as well
2970 C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
2971 A non-blocking socket operation could not be completed immediately.
2975 flock() will now set sensible error codes in $!. Previous Perl versions
2976 copied the value of $^E into $!, which caused much confusion.
2980 select() now supports all empty C<fd_set>s more correctly.
2984 C<'.\foo'> and C<'..\foo'> were treated differently than
2985 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
2989 Improved message window handling means that C<alarm> and C<kill> messages
2990 will no longer be dropped under race conditions.
2994 Various bits of Perl's build infrastructure are no longer converted to
2995 win32 line endings at release time. If this hurts you, please report the
2996 problem with the L<perlbug> program included with perl.
3003 =head1 Known Problems
3005 This is a list of some significant unfixed bugs, which are regressions
3006 from either 5.10.x or 5.8.x.
3012 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
3013 (typically introduced by C<my $_> or implicitly by C<given>). The variable
3014 which gets set for each iteration is the package variable C<$_>, not the
3015 lexical C<$_> [RT #67694].
3017 A similar issue may occur in other modules that provide functions which
3018 take a block as their first argument, like
3020 foo { ... $_ ...} list
3024 Some regexes may run much more slowly when run in a child thread compared
3025 with the thread the pattern was compiled into [RT #55600].
3029 Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
3030 will appear to hang as they get into a very long running loop [RT #72998].
3034 Several porters have reported mysterious crashes when Perl's entire
3035 test suite is run after a build on certain Windows 2000 systems. When
3036 run by hand, the individual tests reportedly work fine.
3046 This one is actually a change introduced in 5.10.0, but it was missed
3047 from that release's perldelta, so it is mentioned here instead.
3049 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
3050 in a change of behaviour between 5.8.x and 5.10.0:
3052 # matches in 5.8.x, doesn't match in 5.10.0
3053 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
3057 =head1 Acknowledgements
3059 Perl 5.12.0 represents approximately two years of development since
3060 Perl 5.10.0 and contains over 750,000 lines of changes across over
3061 3,000 files from over 200 authors and committers.
3063 Perl continues to flourish into its third decade thanks to a vibrant
3064 community of users and developers. The following people are known to
3065 have contributed the improvements that became Perl 5.12.0:
3067 Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
3068 Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
3069 Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
3070 andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
3071 Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
3072 Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
3073 Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
3074 Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
3075 Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
3076 Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
3077 David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
3078 Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
3079 Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
3080 Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
3081 Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
3082 Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
3083 Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
3084 Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
3085 Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
3086 John Peacock, John Peacock via RT, John P. Linderman, John Wright,
3087 Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
3088 Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
3089 Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
3090 Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
3091 Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
3092 G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
3093 Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
3094 Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
3095 Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
3096 Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
3097 Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
3098 Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
3099 Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
3100 Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
3101 Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
3102 Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
3103 The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
3104 Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
3105 Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
3106 Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
3108 This is woefully incomplete as it's automatically generated from version
3109 control history. In particular, it doesn't include the names of the
3110 (very much appreciated) contributors who reported issues in previous
3111 versions of Perl that helped make Perl 5.12.0 better. For a more complete
3112 list of all of Perl's historical contributors, please see the C<AUTHORS>
3113 file in the Perl 5.12.0 distribution.
3115 Many of the changes included in this version originated in the CPAN
3116 modules included in Perl's core. We're grateful to the entire CPAN
3117 community for helping Perl to flourish.
3119 =head1 Reporting Bugs
3121 If you find what you think is a bug, you might check the articles
3122 recently posted to the comp.lang.perl.misc newsgroup and the perl
3123 bug database at L<http://rt.perl.org/perlbug/>. There may also be
3124 information at L<http://www.perl.org/>, the Perl Home Page.
3126 If you believe you have an unreported bug, please run the B<perlbug>
3127 program included with your release. Be sure to trim your bug down
3128 to a tiny but sufficient test case. Your bug report, along with the
3129 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3130 analyzed by the Perl porting team.
3132 If the bug you are reporting has security implications, which make it
3133 inappropriate to send to a publicly archived mailing list, then please send
3134 it to perl5-security-report@perl.org. This points to a closed subscription
3135 unarchived mailing list, which includes all the core committers, who be able
3136 to help assess the impact of issues, figure out a resolution, and help
3137 co-ordinate the release of patches to mitigate or fix the problem across all
3138 platforms on which Perl is supported. Please only use this address for
3139 security issues in the Perl core, not for modules independently
3140 distributed on CPAN.
3144 The F<Changes> file for an explanation of how to view exhaustive details
3147 The F<INSTALL> file for how to build Perl.
3149 The F<README> file for general stuff.
3151 The F<Artistic> and F<Copying> files for copyright information.