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. Affected
294 modules include L<FreezeThaw>,L<Data::Dump::Streamer> and L<Regexp::Copy>.
297 =head2 Switch statement changes
299 The C<given>/C<when> switch statement handles complex statements better
300 than Perl 5.10.0 did (These enhancements are also available in
301 5.10.1 and subsequent 5.10 releases.) There are two new cases where
302 C<when> now interprets its argument as a boolean, instead of an
303 expression to be used in a smart match:
307 =item flip-flop operators
309 The C<..> and C<...> flip-flop operators are now evaluated in boolean
310 context, following their usual semantics; see L<perlop/"Range Operators">.
312 Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
313 whether a given value is an integer between 1 and 10; you should use
314 C<when ([1..10])> instead (note the array reference).
316 However, contrary to 5.10.0, evaluating the flip-flop operators in
317 boolean context ensures it can now be useful in a C<when()>, notably
318 for implementing bistable conditions, like in:
320 when (/^=begin/ .. /^=end/) {
324 =item defined-or operator
326 A compound expression involving the defined-or operator, as in
327 C<when (expr1 // expr2)>, will be treated as boolean if the first
328 expression is boolean. (This just extends the existing rule that applies
329 to the regular or operator, as in C<when (expr1 || expr2)>.)
333 =head2 Smart match changes
335 Since Perl 5.10.0, Perl's developers have made a number of changes to
336 the smart match operator. These, of course, also alter the behaviour
337 of the switch statements where smart matching is implicitly used.
338 These changes were also made for the 5.10.1 release, and will remain in
339 subsequent 5.10 releases.
341 =head3 Changes to type-based dispatch
343 The smart match operator C<~~> is no longer commutative. The behaviour of
344 a smart match now depends primarily on the type of its right hand
345 argument. Moreover, its semantics have been adjusted for greater
346 consistency or usefulness in several cases. While the general backwards
347 compatibility is maintained, several changes must be noted:
353 Code references with an empty prototype are no longer treated specially.
354 They are passed an argument like the other code references (even if they
355 choose to ignore it).
359 C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
360 returns a true value for each key of the hash (or element of the
361 array), instead of passing the whole hash or array as a reference to
366 Due to the commutativity breakage, code references are no longer
367 treated specially when appearing on the left of the C<~~> operator,
368 but like any vulgar scalar.
372 C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
373 hash). No implicit conversion to C<""> is done (as was the case in perl
378 C<$scalar ~~ @array> now always distributes the smart match across the
379 elements of the array. It's true if one element in @array verifies
380 C<$scalar ~~ $element>. This is a generalization of the old behaviour
381 that tested whether the array contained the scalar.
385 The full dispatch table for the smart match operator is given in
386 L<perlsyn/"Smart matching in detail">.
388 =head3 Smart match and overloading
390 According to the rule of dispatch based on the rightmost argument type,
391 when an object overloading C<~~> appears on the right side of the
392 operator, the overload routine will always be called (with a 3rd argument
393 set to a true value, see L<overload>.) However, when the object will
394 appear on the left, the overload routine will be called only when the
395 rightmost argument is a simple scalar. This way, distributivity of smart
396 match across arrays is not broken, as well as the other behaviours with
397 complex types (coderefs, hashes, regexes). Thus, writers of overloading
398 routines for smart match mostly need to worry only with comparing
399 against a scalar, and possibly with stringification overloading; the
400 other common cases will be automatically handled consistently.
402 C<~~> will now refuse to work on objects that do not overload it (in order
403 to avoid relying on the object's underlying structure). (However, if the
404 object overloads the stringification or the numification operators, and
405 if overload fallback is active, it will be used instead, as usual.)
407 =head2 Other potentially incompatible changes
413 The definitions of a number of Unicode properties have changed to match
414 those of the current Unicode standard. These are listed above under
415 L</Unicode overhaul>. This change may break code that expects the old
420 The boolkeys op has moved to the group of hash ops. This breaks binary
425 Filehandles are now always blessed into C<IO::File>.
427 The previous behaviour was to bless Filehandles into L<FileHandle>
428 (an empty proxy class) if it was loaded into memory and otherwise
429 to bless them into C<IO::Handle>.
433 The semantics of C<use feature :5.10*> have changed slightly.
434 See L<"Modules and Pragmata"> for more information.
438 Perl's developers now use git, rather than Perforce. This should be
439 a purely internal change only relevant to people actively working on
440 the core. However, you may see minor difference in perl as a consequence
441 of the change. For example in some of details of the output of C<perl
442 -V>. See L<perlrepository> for more information.
446 As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
447 C<Test::Harness::Straps> module has been removed.
448 See L</"Modules and Pragmata"> for more details.
452 As part of the C<ExtUtils::MakeMaker> upgrade, the
453 C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
454 have been removed from this distribution.
458 C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
463 C<length undef> now returns undef.
467 Unsupported private C API functions are now declared "static" to prevent
468 leakage to Perl's public API.
472 To support the bootstrapping process, F<miniperl> no longer builds with
473 UTF-8 support in the regexp engine.
475 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
476 Without this there's a bootstrapping problem, as miniperl can't load
477 the UTF-8 components of the regexp engine, because they're not yet built.
481 F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
482 C<$ENV{PERL5LIB}>, and "C<.>"
486 A space or a newline is now required after a C<"#line XXX"> directive.
490 Tied filehandles now have an additional method EOF which provides the
495 To better match all other flow control statements, C<foreach> may no
496 longer be used as an attribute.
500 Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
508 From time to time, Perl's developers find it necessary to deprecate
509 features or modules we've previously shipped as part of the core
510 distribution. We are well aware of the pain and frustration that a
511 backwards-incompatible change to Perl can cause for developers building
512 or maintaining software in Perl. You can be sure that when we deprecate
513 a functionality or syntax, it isn't a choice we make lightly. Sometimes,
514 we choose to deprecate functionality or syntax because it was found to
515 be poorly designed or implemented. Sometimes, this is because they're
516 holding back other features or causing performance problems. Sometimes,
517 the reasons are more complex. Wherever possible, we try to keep deprecated
518 functionality available to developers in its previous form for at least
519 one major release. So long as a deprecated feature isn't actively
520 disrupting our ability to maintain and extend Perl, we'll try to leave
521 it in place as long as possible.
523 The following items are now deprecated:
529 C<suidperl> is no longer part of Perl. It used to provide a mechanism to
530 emulate setuid permission bits on systems that don't support it properly.
533 =item Use of C<:=> to mean an empty attribute list
535 An accident of Perl's parser meant that these constructions were all
542 with the C<:> being treated as the start of an attribute list, which
543 ends before the C<=>. As whitespace is not significant here, all are
544 parsed as an empty attribute list, hence all the above are equivalent
545 to, and better written as
549 because no attribute processing is done for an empty list.
551 As is, this meant that C<:=> cannot be used as a new token, without
552 silently changing the meaning of existing code. Hence that particular
553 form is now deprecated, and will become a syntax error. If it is
554 absolutely necessary to have empty attribute lists (for example,
555 because of a code generator) then avoid the warning by adding a space
558 =item C<< UNIVERSAL->import() >>
560 The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
561 pass import arguments to a C<use UNIVERSAL> statement will result in a
565 =item Use of "goto" to jump into a construct
567 Using C<goto> to jump from an outer scope into an inner scope is now
568 deprecated. This rare use case was causing problems in the
569 implementation of scopes.
571 =item Custom character names in \N{name} that don't look like names
573 In C<\N{I<name>}>, I<name> can be just about anything. The standard
574 Unicode names have a very limited domain, but a custom name translator
575 could create names that are, for example, made up entirely of punctuation
576 symbols. It is now deprecated to make names that don't begin with an
577 alphabetic character, and aren't alphanumeric or contain other than
578 a very few other characters, namely spaces, dashes, parentheses
579 and colons. Because of the added meaning of C<\N> (See L</C<\N>
580 experimental regex escape>), names that look like curly brace -enclosed
581 quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
582 4 non-newlines; before a custom name C<3,4> could have been created.
584 =item Deprecated Modules
586 The following modules will be removed from the core distribution in a
587 future release, and should be installed from CPAN instead. Distributions
588 on CPAN which require these should add them to their prerequisites. The
589 core versions of these modules warnings will issue a deprecation warning.
591 If you ship a packaged version of Perl, either alone or as part of a
592 larger system, then you should carefully consider the reprecussions of
593 core module deprecations. You may want to consider shipping your default
594 build of Perl with packages for some or all deprecated modules which
595 install into C<vendor> or C<site> perl library directories. This will
596 inhibit the deprecation warnings.
598 Alternatively, you may want to consider patching F<lib/deprecate.pm>
599 to provide deprecation warnings specific to your packaging system
600 or distribution of Perl, consistent with how your packaging system
601 or distribution manages a staged transition from a release where the
602 installation of a single package provides the given functionality, to
603 a later release where the system administrator needs to know to install
604 multiple packages to get that same functionality.
606 You can silence these deprecation warnings by installing the modules
607 in question from CPAN. To install the latest version of all of them,
608 just install C<Task::Deprecations::5_12>.
614 =item L<Pod::Plainer>
620 Switch is buggy and should be avoided. You may find Perl's new
621 C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
622 statements"> for more information.
626 =item Assignment to $[
628 =item Use of the attribute :locked on subroutines
630 =item Use of "locked" with the attributes pragma
632 =item Use of "unique" with the attributes pragma
636 C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
637 generates a deprecation warning, and it will be removed in a future
638 release. Although listed as part of the API, it was never documented,
639 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
640 core, it has been replaced by a static function.
642 =item Numerous Perl 4-era libraries
644 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
645 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
646 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
647 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
648 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
649 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
650 F<timelocal.pl> are all now deprecated. Using them will incur a warning.
655 =head1 Unicode overhaul
657 Perl's developers have made a concerted effort to update Perl to be in
658 sync with the latest Unicode standard. Changes for this include:
660 Perl can now handle every Unicode character property. New documentation,
661 L<perluniprops>, lists all available non-Unihan character properties. By
662 default, perl does not expose Unihan, deprecated or Unicode-internal
663 properties. See below for more details on these; there is also a section
664 in the pod listing them, and explaining why they are not exposed.
666 Perl now fully supports the Unicode compound-style of using C<=>
667 and C<:> in writing regular expressions: C<\p{property=value}> and
668 C<\p{property:value}> (both of which mean the same thing).
670 Perl now fully supports the Unicode loose matching rules for text between
671 the braces in C<\p{...}> constructs. In addition, Perl allows underscores
672 between digits of numbers.
674 Perl now accepts all the Unicode-defined synonyms for properties and
677 C<qr/\X/>, which matches a Unicode logical character, has
678 been expanded to work better with various Asian languages. It
679 now is defined as an I<extended grapheme cluster>. (See
680 L<http://www.unicode.org/reports/tr29/>). Anything matched previously
681 and that made sense will continue to be accepted. Additionally:
687 C<\X> will not break apart a C<S<CR LF>> sequence.
691 C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
696 C<\X> will now always match at least one character, including an initial
697 mark. Marks generally come after a base character, but it is possible in
698 Unicode to have them in isolation, and C<\X> will now handle that case,
699 for example at the beginning of a line, or after a C<ZWSP>. And this is
700 the part where C<\X> doesn't match the things that it used to that don't
701 make sense. Formerly, for example, you could have the nonsensical case
706 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
707 and Lao exception cases.
711 Otherwise, this change should be transparent for the non-affected
714 C<\p{...}> matches using the Canonical_Combining_Class property were
715 completely broken in previous releases of Perl. They should now work
718 Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
719 and a Perl extension had the same name, which led to neither matching
720 all the correct values (with more than 100 mistakes in one, and several
721 thousand in the other). The Perl extension has now been renamed to be
722 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
723 same meaning as was previously intended, namely the union of all the
724 non-canonical Decomposition types, with Unicode C<Compat> being just
727 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
729 C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
730 says they should. This means they each match a few more characters than
733 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
734 means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
735 nor Format (gc=cf) code points. The Format code points represent the
736 biggest possible problem. All but 36 of them are either officially
737 deprecated or strongly discouraged from being used. Of those 36, likely
738 the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
739 WJ, and similar characters, plus bidirectional controls.
741 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
742 5.12, Perl's definition definition included a number of things that aren't
743 really alpha (all marks) while omitting many that were. The definitions
744 of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
747 C<\p{Word}> no longer incorrectly matches non-word characters such
750 C<\p{Print}> no longer matches the line control characters: Tab, LF,
751 CR, FF, VT, and NEL. This brings it in line with standards and the
754 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
755 means that in addition to the characters it currently matches,
756 C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
757 example U+FF10: FULLWIDTH DIGIT ZERO.
759 The Numeric type property has been extended to include the Unihan
762 There is a new Perl extension, the 'Present_In', or simply 'In',
763 property. This is an extension of the Unicode Age property, but
764 C<\p{In=5.0}> matches any code point whose usage has been determined
765 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
766 added in I<precisely> version 5.0.
768 A number of properties now have the correct values for unassigned
769 code points. The affected properties are Bidi_Class, East_Asian_Width,
770 Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
773 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
774 are now up to date with current Unicode definitions.
776 Earlier versions of Perl erroneously exposed certain properties that
777 are supposed to be Unicode internal-only. Use of these in regular
778 expressions will now generate, if enabled, a deprecation warning message.
779 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
780 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
781 Other_Math, and Other_Uppercase.
783 It is now possible to change which Unicode properties Perl understands
784 on a per-installation basis. As mentioned above, certain properties
785 are turned off by default. These include all the Unihan properties
786 (which should be accessible via the CPAN module Unicode::Unihan) and any
787 deprecated or Unicode internal-only property that Perl has never exposed.
789 The generated files in the C<lib/unicore/To> directory are now more
790 clearly marked as being stable, directly usable by applications. New hash
791 entries in them give the format of the normal entries, which allows for
792 easier machine parsing. Perl can generate files in this directory for
793 any property, though most are suppressed. You can find instructions
794 for changing which are written in L<perluniprops>.
796 =head1 Modules and Pragmata
798 =head2 New Modules and Pragmata
804 C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
805 The bundled version is 2.06_01. Note that in this release, using a string
806 eval when C<autodie> is in effect can cause the autodie behaviour to leak
807 into the surrounding scope. See L<autodie/"BUGS"> for more details.
809 Version 2.06_01 has been added to the Perl core.
811 =item C<Compress::Raw::Bzip2>
813 Version 2.024 has been added to the Perl core.
817 C<overloading> allows you to lexically disable or enable overloading
818 for some or all operations.
820 Version 0.001 has been added to the Perl core.
824 C<parent> establishes an ISA relationship with base classes at compile
825 time. It provides the key feature of C<base> without further unwanted
828 Version 0.223 has been added to the Perl core.
830 =item C<Parse::CPAN::Meta>
832 Version 1.40 has been added to the Perl core.
836 Version 1.03 has been added to the Perl core.
840 Version 2.4 has been added to the Perl core.
842 =item C<XS::APItest::KeywordRPN>
844 Version 0.003 has been added to the Perl core.
848 =head2 Updated Pragmata
854 Upgraded from version 2.13 to 2.15.
858 Upgraded from version 0.22 to 0.23.
862 C<charnames> now contains the Unicode F<NameAliases.txt> database file.
863 This has the effect of adding some extra C<\N> character names that
864 formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
867 Upgraded from version 1.06 to 1.07.
871 Upgraded from version 1.13 to 1.20.
875 C<diagnostics> now supports %.0f formatting internally.
877 C<diagnostics> no longer suppresses C<Use of uninitialized value in range
878 (or flip)> warnings. [perl #71204]
880 Upgraded from version 1.17 to 1.19.
884 In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
885 bundles has changed slightly. The last component, if any (i.e. C<X>) is
886 simply ignored. This is predicated on the assumption that new features
887 will not, in general, be added to maintenance releases. So C<:5.10>
888 and C<:5.10.X> have identical effect. This is a change to the behaviour
889 documented for 5.10.0.
891 C<feature> now includes the C<unicode_strings> feature:
893 use feature "unicode_strings";
895 This pragma turns on Unicode semantics for the case-changing operations
896 (C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
897 internal UTF-8 flag set, but that contain single-byte characters between
900 Upgraded from version 1.11 to 1.16.
904 C<less> now includes the C<stash_name> method to allow subclasses of
905 C<less> to pick where in %^H to store their stash.
907 Upgraded from version 0.02 to 0.03.
911 Upgraded from version 0.5565 to 0.62.
915 C<mro> is now implemented as an XS extension. The documented interface has
916 not changed. Code relying on the implementation detail that some C<mro::>
917 methods happened to be available at all times gets to "keep both pieces".
919 Upgraded from version 1.00 to 1.02.
923 C<overload> now allow overloading of 'qr'.
925 Upgraded from version 1.06 to 1.10.
929 Upgraded from version 1.67 to 1.75.
931 =item C<threads::shared>
933 Upgraded from version 1.14 to 1.32.
937 C<version> now has support for L</Version number formats> as described
938 earlier in this document and in its own documentation.
940 Upgraded from version 0.74 to 0.82.
944 C<warnings> has a new C<warnings::fatal_enabled()> function. It also
945 includes a new C<illegalproto> warning category. See also L</New or
946 Changed Diagnostics> for this change.
948 Upgraded from version 1.06 to 1.09.
952 =head2 Updated Modules
956 =item C<Archive::Extract>
958 Upgraded from version 0.24 to 0.38.
960 =item C<Archive::Tar>
962 Upgraded from version 1.38 to 1.54.
964 =item C<Attribute::Handlers>
966 Upgraded from version 0.79 to 0.87.
970 Upgraded from version 5.63 to 5.70.
974 Upgraded from version 0.74 to 0.78.
978 Upgraded from version 1.05 to 1.12.
982 Upgraded from version 0.83 to 0.96.
986 Upgraded from version 1.09 to 1.11_01.
990 Upgraded from version 3.29 to 3.48.
994 Upgraded from version 0.33 to 0.36.
996 NOTE: C<Class::ISA> is deprecated and may be removed from a future
999 =item C<Compress::Raw::Zlib>
1001 Upgraded from version 2.008 to 2.024.
1005 Upgraded from version 1.9205 to 1.94_56.
1009 Upgraded from version 0.84 to 0.90.
1011 =item C<CPANPLUS::Dist::Build>
1013 Upgraded from version 0.06_02 to 0.46.
1015 =item C<Data::Dumper>
1017 Upgraded from version 2.121_14 to 2.125.
1021 Upgraded from version 1.816_1 to 1.820.
1023 =item C<Devel::PPPort>
1025 Upgraded from version 3.13 to 3.19.
1029 Upgraded from version 1.15 to 1.16.
1031 =item C<Digest::MD5>
1033 Upgraded from version 2.36_01 to 2.39.
1035 =item C<Digest::SHA>
1037 Upgraded from version 5.45 to 5.47.
1041 Upgraded from version 2.23 to 2.39.
1045 Upgraded from version 5.62 to 5.64_01.
1047 =item C<ExtUtils::CBuilder>
1049 Upgraded from version 0.21 to 0.27.
1051 =item C<ExtUtils::Command>
1053 Upgraded from version 1.13 to 1.16.
1055 =item C<ExtUtils::Constant>
1057 Upgraded from version 0.2 to 0.22.
1059 =item C<ExtUtils::Install>
1061 Upgraded from version 1.44 to 1.55.
1063 =item C<ExtUtils::MakeMaker>
1065 Upgraded from version 6.42 to 6.56.
1067 =item C<ExtUtils::Manifest>
1069 Upgraded from version 1.51_01 to 1.57.
1071 =item C<ExtUtils::ParseXS>
1073 Upgraded from version 2.18_02 to 2.21.
1075 =item C<File::Fetch>
1077 Upgraded from version 0.14 to 0.24.
1081 Upgraded from version 2.04 to 2.08_01.
1085 Upgraded from version 0.18 to 0.22.
1087 =item C<Filter::Simple>
1089 Upgraded from version 0.82 to 0.84.
1091 =item C<Filter::Util::Call>
1093 Upgraded from version 1.07 to 1.08.
1095 =item C<Getopt::Long>
1097 Upgraded from version 2.37 to 2.38.
1101 Upgraded from version 1.23_01 to 1.25_02.
1105 Upgraded from version 1.07 to 1.10.
1109 Upgraded from version 0.40_1 to 0.54.
1113 Upgraded from version 1.05 to 2.01.
1115 =item C<Locale::Maketext>
1117 Upgraded from version 1.12 to 1.14.
1119 =item C<Locale::Maketext::Simple>
1121 Upgraded from version 0.18 to 0.21.
1123 =item C<Log::Message>
1125 Upgraded from version 0.01 to 0.02.
1127 =item C<Log::Message::Simple>
1129 Upgraded from version 0.04 to 0.06.
1131 =item C<Math::BigInt>
1133 Upgraded from version 1.88 to 1.89_01.
1135 =item C<Math::BigInt::FastCalc>
1137 Upgraded from version 0.16 to 0.19.
1139 =item C<Math::BigRat>
1141 Upgraded from version 0.21 to 0.24.
1143 =item C<Math::Complex>
1145 Upgraded from version 1.37 to 1.56.
1149 Upgraded from version 1.01_02 to 1.01_03.
1151 =item C<MIME::Base64>
1153 Upgraded from version 3.07_01 to 3.08.
1155 =item C<Module::Build>
1157 Upgraded from version 0.2808_01 to 0.3603.
1159 =item C<Module::CoreList>
1161 Upgraded from version 2.12 to 2.29.
1163 =item C<Module::Load>
1165 Upgraded from version 0.12 to 0.16.
1167 =item C<Module::Load::Conditional>
1169 Upgraded from version 0.22 to 0.34.
1171 =item C<Module::Loaded>
1173 Upgraded from version 0.01 to 0.06.
1175 =item C<Module::Pluggable>
1177 Upgraded from version 3.6 to 3.9.
1181 Upgraded from version 2.33 to 2.36.
1185 Upgraded from version 0.60_01 to 0.64.
1187 =item C<Object::Accessor>
1189 Upgraded from version 0.32 to 0.36.
1191 =item C<Package::Constants>
1193 Upgraded from version 0.01 to 0.02.
1197 Upgraded from version 1.04 to 1.06.
1199 =item C<Pod::Parser>
1201 Upgraded from version 1.35 to 1.37.
1203 =item C<Pod::Perldoc>
1205 Upgraded from version 3.14_02 to 3.15_02.
1207 =item C<Pod::Plainer>
1209 Upgraded from version 0.01 to 1.02.
1211 NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
1214 =item C<Pod::Simple>
1216 Upgraded from version 3.05 to 3.13.
1220 Upgraded from version 2.12 to 2.22.
1224 Upgraded from version 1.11 to 1.17.
1228 Upgraded from version 2.18 to 2.22.
1232 Upgraded from version 2.13 to 2.16.
1234 NOTE: C<Switch> is deprecated and may be removed from a future version
1237 =item C<Sys::Syslog>
1239 Upgraded from version 0.22 to 0.27.
1241 =item C<Term::ANSIColor>
1243 Upgraded from version 1.12 to 2.02.
1247 Upgraded from version 0.18 to 0.20.
1251 Upgraded from version 1.25 to 1.25_02.
1253 =item C<Test::Harness>
1255 Upgraded from version 2.64 to 3.17.
1257 =item C<Test::Simple>
1259 Upgraded from version 0.72 to 0.94.
1261 =item C<Text::Balanced>
1263 Upgraded from version 2.0.0 to 2.02.
1265 =item C<Text::ParseWords>
1267 Upgraded from version 3.26 to 3.27.
1269 =item C<Text::Soundex>
1271 Upgraded from version 3.03 to 3.03_01.
1273 =item C<Thread::Queue>
1275 Upgraded from version 2.00 to 2.11.
1277 =item C<Thread::Semaphore>
1279 Upgraded from version 2.01 to 2.09.
1281 =item C<Tie::RefHash>
1283 Upgraded from version 1.37 to 1.38.
1285 =item C<Time::HiRes>
1287 Upgraded from version 1.9711 to 1.9719.
1289 =item C<Time::Local>
1291 Upgraded from version 1.18 to 1.1901_01.
1293 =item C<Time::Piece>
1295 Upgraded from version 1.12 to 1.15.
1297 =item C<Unicode::Collate>
1299 Upgraded from version 0.52 to 0.52_01.
1301 =item C<Unicode::Normalize>
1303 Upgraded from version 1.02 to 1.03.
1307 Upgraded from version 0.34 to 0.39.
1309 =item C<Win32API::File>
1311 Upgraded from version 0.1001_01 to 0.1101.
1315 Upgraded from version 0.08 to 0.10.
1319 =head2 Removed Modules and Pragmata
1325 Removed from the Perl core. Prior version was 1.02.
1327 =item C<CPAN::API::HOWTO>
1329 Removed from the Perl core. Prior version was 'undef'.
1331 =item C<CPAN::DeferedCode>
1333 Removed from the Perl core. Prior version was 5.50.
1335 =item C<CPANPLUS::inc>
1337 Removed from the Perl core. Prior version was 'undef'.
1341 Removed from the Perl core. Prior version was 1.03.
1343 =item C<ExtUtils::MakeMaker::bytes>
1345 Removed from the Perl core. Prior version was 6.42.
1347 =item C<ExtUtils::MakeMaker::vmsish>
1349 Removed from the Perl core. Prior version was 6.42.
1353 Removed from the Perl core. Prior version was 2.3.
1355 =item C<Test::Harness::Assert>
1357 Removed from the Perl core. Prior version was 0.02.
1359 =item C<Test::Harness::Iterator>
1361 Removed from the Perl core. Prior version was 0.02.
1363 =item C<Test::Harness::Point>
1365 Removed from the Perl core. Prior version was 0.01.
1367 =item C<Test::Harness::Results>
1369 Removed from the Perl core. Prior version was 0.01.
1371 =item C<Test::Harness::Straps>
1373 Removed from the Perl core. Prior version was 0.26_01.
1375 =item C<Test::Harness::Util>
1377 Removed from the Perl core. Prior version was 0.01.
1381 Removed from the Perl core. Prior version was 1.1.
1385 =head2 Deprecated Modules and Pragmata
1387 See L</Deprecated Modules> above.
1390 =head1 Documentation
1392 =head2 New Documentation
1398 L<perlhaiku> contains instructions on how to build perl for the Haiku
1403 L<perlmroapi> describes the new interface for pluggable Method Resolution
1408 L<perlperf>, by Richard Foley, provides an introduction to the use of
1409 performance and optimization techniques which can be used with particular
1410 reference to perl programs.
1414 L<perlrepository> describes how to access the perl source using the I<git>
1415 version control system.
1419 L<perlpolicy> extends the "Social contract about contributed modules" into
1420 the beginnings of a document on Perl porting policies.
1424 =head2 Changes to Existing Documentation
1432 The various large F<Changes*> files (which listed every change made
1433 to perl over the last 18 years) have been removed, and replaced by a
1434 small file, also called F<Changes>, which just explains how that same
1435 information may be extracted from the git version control system.
1439 F<Porting/patching.pod> has been deleted, as it mainly described
1440 interacting with the old Perforce-based repository, which is now obsolete.
1441 Information still relevant has been moved to L<perlrepository>.
1446 The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
1447 as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
1448 BLOCK>, although actually using the latter may not be the best idea for
1449 the readability of your source code.
1454 Documented -X overloading.
1458 Documented that C<when()> treats specially most of the filetest operators
1462 Documented C<when> as a syntax modifier.
1466 Eliminated "Old Perl threads tutorial", which described 5005 threads.
1468 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1472 Correct previous documentation: v-strings are not deprecated
1474 With version objects, we need them to use MODULE VERSION syntax. This
1475 patch removes the deprecation notice.
1479 Security contact information is now part of L<perlsec>.
1483 A significant fraction of the core documentation has been updated to
1484 clarify the behavior of Perl's Unicode handling.
1486 Much of the remaining core documentation has been reviewed and edited
1487 for clarity, consistent use of language, and to fix the spelling of Tom
1488 Christiansen's name.
1492 The Pod specification (L<perlpodspec>) has been updated to bring the
1493 specification in line with modern usage already supported by most Pod
1494 systems. A parameter string may now follow the format name in a
1495 "begin/end" region. Links to URIs with a text description are now
1496 allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
1501 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1502 conditional loading of modules despite the implicit BEGIN block around
1507 The documentation for C<$1> in perlvar.pod has been clarified.
1511 C<\N{U+I<wide hex char>}> is now documented.
1515 =head1 Selected Performance Enhancements
1521 A new internal cache means that C<isa()> will often be faster.
1525 The implementation of C<C3> Method Resolution Order has been
1526 optimised - linearisation for classes with single inheritance is 40%
1527 faster. Performance for multiple inheritance is unchanged.
1531 Under C<use locale>, the locale-relevant information is now cached on
1532 read-only values, such as the list returned by C<keys %hash>. This makes
1533 operations such as C<sort keys %hash> in the scope of C<use locale>
1538 Empty C<DESTROY> methods are no longer called.
1542 C<Perl_sv_utf8_upgrade()> is now faster.
1546 C<keys> on empty hash is now faster.
1550 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
1554 The string repetition operator (C<$str x $num>) is now several times
1555 faster when C<$str> has length one or C<$num> is large.
1559 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1560 now happens in-place and is several orders of magnitude faster than
1561 it used to be. It will also preserve non-existent elements whenever
1562 possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
1563 and C<DELETE> methods.
1567 =head1 Installation and Configuration Improvements
1573 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
1574 generated at build time, rather than being shipped as part of the release.
1578 If C<vendorlib> and C<vendorarch> are the same, then they are only added
1583 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1584 perl is built with C<-Dusedevel>.
1588 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1589 against stack-smashing attacks, if the compiler supports it.
1593 F<Configure> will now determine the correct prototypes for re-entrant
1594 functions and for C<gconvert> if you are using a C++ compiler rather
1599 On Unix, if you build from a tree containing a git repository, the
1600 configuration process will note the commit hash you have checked out, for
1601 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1602 are automatically added to the list of local patches displayed by
1607 Perl now supports SystemTap's C<dtrace> compatibility layer and an
1608 issue with linking C<miniperl> has been fixed in the process.
1612 perldoc now uses C<less -R> instead of C<less> for improved behaviour
1613 in the face of C<groff>'s new usage of ANSI escape codes.
1618 C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
1619 C<USE_ATTRIBUTES_FOR_PERLIO>.
1623 As part of the flattening of F<ext>, all extensions on all platforms are
1624 built by F<make_ext.pl>. This replaces the Unix-specific
1625 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1626 F<win32/buildext.pl>.
1630 =head1 Internal Changes
1632 Each release of Perl sees numerous internal changes which shouldn't
1633 affect day to day usage but may still be notable for developers working
1634 with Perl's source code.
1640 The J.R.R. Tolkien quotes at the head of C source file have been checked
1641 and proper citations added, thanks to a patch from Tom Christiansen.
1645 The internal structure of the dual-life modules traditionally found in
1646 the F<lib/> and F<ext/> directories y in the perl source has changed
1647 significantly. Where possible, dual-lifed modules have been extracted
1648 from F<lib/> and F<ext/>.
1650 Dual-lifed modules maintained by Perl's developers as part of the Perl
1651 core now live in F<dist/>. Dual-lifed modules maintained primarily on
1652 CPAN now live in F<cpan/>. When reporting a bug in a module located
1653 under F<cpan/>, please send your bug report directly to the module's
1654 bug tracker or author, rather than Perl's bug tracker.
1658 C<\N{...}> now compiles better, always forces UTF-8 internal representation
1660 Perl's developers have fixed several problems with the recognition of
1661 C<\N{...}> constructs. As part of this, perl will store any scalar
1662 or regex containing C<\N{I<name>}> or C<\N{U+I<wide hex char>}> in its
1663 definition in UTF-8 format. (This was true previously for all occurences
1664 of C<\N{I<name>}> that did not use a custom translator, but now it's
1669 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1673 C<SVt_RV> no longer exists. RVs are now stored in IVs.
1677 C<Perl_vcroak()> now accepts a null first argument. In addition, a full
1678 audit was made of the "not NULL" compiler annotations, and those for
1679 several other internal functions were corrected.
1683 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1684 have been added to formalise the temporary saving of the C<errno>
1689 The function C<Perl_sv_insert_flags> has been added to augment
1694 The function C<Perl_newSV_type(type)> has been added, equivalent to
1695 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1699 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1700 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1702 Two flag bits are currently supported.
1708 C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
1709 not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
1710 C<newSVpvn_utf8()> is available for this.
1714 C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
1718 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1722 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1727 Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
1731 C<PL_na> has been exterminated from the core code, replaced by local
1732 STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
1733 C<PL_na>, which is a pointer dereference into the interpreter structure
1734 under ithreads, and a global variable otherwise.
1738 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
1739 on the scalar. It now updates the linked list to remove each piece of
1740 magic as it is freed.
1744 Under ithreads, the regex in C<PL_reg_curpm> is now reference
1745 counted. This eliminates a lot of hackish workarounds to cope with it
1746 not being reference counted.
1750 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1751 This has been fixed.
1755 The I<public> IV and NV flags are now not set if the string value has
1756 trailing "garbage". This behaviour is consistent with not setting the
1757 public IV or NV flags if the value is out of range for the type.
1761 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
1762 been replaced by C<NULL> in the core code, and non-dual-life modules,
1763 as C<NULL> is clearer to those unfamiliar with the core code.
1767 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1768 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1769 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1770 casting away C<const>. This allows proper compile-time auditing of
1771 C<const> correctness in the core, and helped picked up some errors
1776 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1777 stack and mortalizing them.
1781 Use of the private structure C<mro_meta> has changed slightly. Nothing
1782 outside the core should be accessing this directly anyway.
1786 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1787 to view how a C preprocessor macro would be expanded when compiled.
1788 This is handy when trying to decode the macro hell that is the perl
1795 =head2 Testing improvements
1799 =item Parallel tests
1801 The core distribution can now run its regression tests in parallel on
1802 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
1803 your environment to the number of tests to run in parallel, and run
1804 C<make test_harness>. On a Bourne-like shell, this can be done as
1806 TEST_JOBS=3 make test_harness # Run 3 tests in parallel
1808 An environment variable is used, rather than parallel make itself, because
1809 L<TAP::Harness> needs to be able to schedule individual non-conflicting test
1810 scripts itself, and there is no standard interface to C<make> utilities to
1811 interact with their job schedulers.
1813 Note that currently some test scripts may fail when run in parallel (most
1814 notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
1815 again sequentially and see if the failures go away.
1817 =item Test harness flexibility
1819 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1823 Several tests that have the potential to hang forever if they fail now
1824 incorporate a "watchdog" functionality that will kill them after a timeout,
1825 which helps ensure that C<make test> and C<make test_harness> run to
1826 completion automatically.
1833 Perl's developers have added a number of new tests to the core.
1834 In addition to the items listed below, many modules updated from CPAN
1835 incorporate new tests.
1841 Significant cleanups to core tests to ensure that language and
1842 interpreter features are not used before they're tested.
1846 C<make test_porting> now runs a number of important pre-commit checks
1847 which might be of use to anyone working on the Perl core.
1851 F<t/porting/podcheck.t> automatically checks the well-formedness of
1852 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1853 dual-lifed modules which are primarily maintained outside the Perl core.
1857 F<t/porting/manifest.t> now tests that all files listed in MANIFEST
1862 F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
1866 F<t/comp/retainedlines.t> checks that the debugger can retain source
1871 F<t/io/perlio_fail.t> checks that bad layers fail.
1875 F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
1879 F<t/io/perlio_open.t> checks that certain special forms of open work.
1883 F<t/io/perlio.t> includes general PerlIO tests.
1887 F<t/io/pvbm.t> checks that there is no unexpected interaction between
1888 the internal types C<PVBM> and C<PVGV>.
1892 F<t/mro/package_aliases.t> checks that mro works properly in the presence
1893 of aliased packages.
1897 F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
1901 F<t/op/index_thr.t> tests the interaction of C<index> and threads.
1905 F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
1909 F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
1913 F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
1917 F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
1918 embedded C<qr//> and threads.
1922 F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
1927 F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
1928 properties and threads.
1932 F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
1936 F<t/op/reg_posixcc.t> checks that POSIX character classes behave
1941 F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
1945 F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
1949 F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
1953 F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
1957 F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
1961 F<t/uni/tie.t> checks that Unicode and C<tie> work.
1965 F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
1969 F<t/comp/form_scope.t> tests format scoping.
1973 F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
1977 F<t/op/filetest_t.t> tests if -t file test works.
1981 F<t/op/qr.t> tests C<qr>.
1985 F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
1989 F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
1993 F<t/op/filehandle.t> tests some suitably portable filetest operators
1994 to check that they work as expected, particularly in the light of some
1995 internal changes made in how filehandles are blessed.
1999 F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
2000 can now be handed to C<gmtime> and C<localtime>, do not cause an internal
2001 overflow or an excessively long loop.
2006 =head1 New or Changed Diagnostics
2008 =head2 New Diagnostics
2014 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
2015 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
2016 that was enabled when the F<perl> binary was compiled.
2020 Smartmatch resolution tracing has been added as a new diagnostic. Use
2021 C<-DM> to enable it.
2025 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
2026 C<-Dx> for its original purpose of dumping syntax trees.
2030 Perl 5.12 provides a number of new diagnostic messages to help you write
2031 better code. See L<perldiag> for details of these new messages.
2037 C<Bad plugin affecting keyword '%s'>
2041 C<gmtime(%.0f) too large>
2045 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
2049 C<Lexing code internal error (%s)>
2053 C<localtime(%.0f) too large>
2057 C<Overloaded dereference did not return a reference>
2061 C<Overloaded qr did not return a REGEXP>
2065 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
2069 C<lvalue attribute ignored after the subroutine has been defined>
2071 This new warning is issued when one attempts to mark a subroutine as
2072 lvalue after it has been defined.
2076 Perl now warns you if C<++> or C<--> are unable to change the value
2077 because it's beyond the limit of representation.
2079 This uses a new warnings category: "imprecision".
2083 C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
2087 C<Show constant in "Useless use of a constant in void context">
2091 C<Prototype after '%s'>
2095 C<panic: sv_chop %s>
2097 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
2098 passed a position that is not within the scalar's string buffer. This
2099 could be caused by buggy XS code, and at this point recovery is not
2105 The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
2106 C<charnames> handler returns malformed UTF-8.
2110 If an unresolved named character or sequence was encountered when
2111 compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
2112 by the lexer> is now produced. This can happen, for example, when using a
2113 single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
2114 for more examples of how the lexer can get bypassed.
2118 C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
2119 triggered when the character constant represented by C<...> is not a
2120 valid hexadecimal number.
2124 The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
2125 class, just like C<.> in a character class loses its special meaning,
2126 and will cause the fatal error C<\N in a character class must be a named
2127 character: \N{...}>.
2131 The rules on what is legal for the C<...> in C<\N{...}> have been
2132 tightened up so that unless the C<...> begins with an alphabetic
2133 character and continues with a combination of alphanumerics, dashes,
2134 spaces, parentheses or colons then the warning C<Deprecated character(s)
2135 in \N{...} starting at '%s'> is now issued.
2139 The warning C<Using just the first characters returned by \N{}> will
2140 be issued if the C<charnames> handler returns a sequence of characters
2141 which exceeds the limit of the number of characters that can be used. The
2142 message will indicate which characters were used and which were discarded.
2148 =head2 Changed Diagnostics
2150 A number of existing diagnostic messages have been improved or corrected:
2156 A new warning category C<illegalproto> allows finer-grained control of
2157 warnings around function prototypes.
2163 =item C<Illegal character in prototype for %s : %s>
2165 =item C<Prototype after '%c' for %s : %s>
2169 have been moved from the C<syntax> top-level warnings category into a new
2170 first-level category, C<illegalproto>. These two warnings are currently
2171 the only ones emitted during parsing of an invalid/illegal prototype,
2174 no warnings 'illegalproto';
2176 to suppress only those, but not other syntax-related warnings. Warnings
2177 where prototypes are changed, ignored, or not met are still in the
2178 C<prototype> category as before.
2182 C<Deep recursion on subroutine "%s">
2184 It is now possible to change the depth threshold for this warning from the
2185 default of 100, by recompiling the F<perl> binary, setting the C
2186 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
2190 C<Illegal character in prototype> warning is now more precise
2191 when reporting illegal characters after _
2195 mro merging error messages are now very similar to those produced by
2200 Amelioration of the error message "Unrecognized character %s in column %d"
2202 Changes the error message to "Unrecognized character %s; marked by E<lt>--
2203 HERE after %sE<lt>-- HERE near column %d". This should make it a little
2204 simpler to spot and correct the suspicious character.
2208 Perl now explicitly points to C<$.> when it causes an uninitialized
2209 warning for ranges in scalar context.
2213 C<split> now warns when called in void context.
2217 C<printf>-style functions called with too few arguments will now issue the
2218 warning C<"Missing argument in %s"> [perl #71000]
2222 Perl now properly returns a syntax error instead of segfaulting
2223 if C<each>, C<keys>, or C<values> is used without an argument.
2227 C<tell()> now fails properly if called without an argument and when no
2228 previous file was read.
2230 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
2231 the 5.8.x behaviour.
2235 C<overload> no longer implicitly unsets fallback on repeated 'use
2240 POSIX::strftime() can now handle Unicode characters in the format string.
2244 The C<syntax> category was removed from 5 warnings that should only be in
2249 Three fatal C<pack>/C<unpack> error messages have been normalized to
2254 C<Unicode character is illegal> has been rephrased to be more accurate
2256 It now reads C<Unicode non-character is illegal in interchange> and the
2257 perldiag documentation has been expanded a bit.
2261 Currently, all but the first of the several characters that the
2262 C<charnames> handler may return are discarded when used in a regular
2263 expression pattern bracketed character class. If this happens then the
2264 warning C<Using just the first character returned by \N{} in character
2265 class> will be issued.
2269 The warning C<Missing right brace on \N{} or unescaped left brace after
2270 \N. Assuming the latter> will be issued if Perl encounters a C<\N{>
2271 but doesn't find a matching C<}>. In this case Perl doesn't know if it
2272 was mistakenly omitted, or if "match non-newline" followed by "match
2273 a C<{>" was desired. It assumes the latter because that is actually a
2274 valid interpretation as written, unlike the other case. If you meant
2275 the former, you need to add the matching right brace. If you did mean
2276 the latter, you can silence this warning by writing instead C<\N\{>.
2280 C<gmtime> and C<localtime> called with numbers smaller than they can
2281 reliably handle will now issue the warnings C<gmtime(%.0f) too small>
2282 and C<localtime(%.0f) too small>.
2286 The following diagnostic messages have been removed:
2296 C<Can't locate package %s for the parents of %s>
2298 In general this warning it only got produced in
2299 conjunction with other warnings, and removing it allowed an ISA lookup
2300 optimisation to be added.
2304 C<v-string in use/require is non-portable>
2308 =head1 Utility Changes
2314 F<h2ph> now looks in C<include-fixed> too, which is a recent addition
2315 to gcc's search path.
2319 F<h2xs> no longer incorrectly treats enum values like macros.
2320 It also now handles C++ style comments (C<//>) properly in enums.
2324 F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
2325 debugger now correctly handles proxy constant subroutines, and
2330 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
2331 upstream bug tracker URLs. If a user identifies a particular module
2332 as the topic of their bug report and we're able to divine the URL for
2333 its upstream bug tracker, perlbug now provide a message to the user
2334 explaining that the core copies the CPAN version directly, and provide
2335 the URL for reporting the bug directly to the upstream author.
2337 F<perlbug> no longer reports "Message sent" when it hasn't actually sent
2342 F<perlthanks> is a new utility for sending non-bug-reports to the
2343 authors and maintainers of Perl. Getting nothing but bug reports can
2344 become a bit demoralising. If Perl 5.12 works well for you, please try
2345 out F<perlthanks>. It will make the developers smile.
2349 Perl's developers have fixed bugs in F<a2p> having to do with the
2350 C<match()> operator in list context. Additionally, F<a2p> no longer
2351 generates code that uses the C<$[> variable.
2355 =head1 Selected Bug Fixes
2361 U+0FFFF is now a legal character in regular expressions.
2365 pp_qr now always returns a new regexp SV. Resolves RT #69852.
2367 Instead of returning a(nother) reference to the (pre-compiled) regexp
2368 in the optree, use reg_temp_copy() to create a copy of it, and return a
2369 reference to that. This resolves issues about Regexp::DESTROY not being
2370 called in a timely fashion (the original bug tracked by RT #69852), as
2371 well as bugs related to blessing regexps, and of assigning to regexps,
2372 as described in correspondence added to the ticket.
2374 It transpires that we also need to undo the SvPVX() sharing when ithreads
2375 cloning a Regexp SV, because mother_re is set to NULL, instead of a
2376 cloned copy of the mother_re. This change might fix bugs with regexps
2377 and threads in certain other situations, but as yet neither tests nor
2378 bug reports have indicated any problems, so it might not actually be an
2379 edge case that it's possible to reach.
2383 Several compilation errors and segfaults when perl was built with C<-Dmad>
2388 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
2392 C<-t> should only return TRUE for file handles connected to a TTY
2394 The Microsoft C version of C<isatty()> returns TRUE for all character mode
2395 devices, including the F</dev/null>-style "nul" device and printers like
2400 Fixed a regression caused by commit fafafbaf which caused a panic during
2401 parameter passing [perl #70171]
2405 On systems which in-place edits without backup files, -i'*' now works as
2406 the documentation says it does [perl #70802]
2410 Saving and restoring magic flags no longer loses readonly flag.
2414 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
2415 causes abrupt and total failure.
2419 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
2424 Using named subroutines with C<sort> should no longer lead to bus errors
2429 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
2433 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
2437 C<$@> may now be assigned a read-only value (without error or busting
2442 C<sort> called recursively from within an active comparison subroutine no
2443 longer causes a bus error if run multiple times. [perl #71076]
2447 Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
2451 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
2456 C<-I> on shebang line now adds directories in front of @INC
2457 as documented, and as does C<-I> when specified on the command-line.
2461 C<kill> is now fatal when called on non-numeric process identifiers.
2462 Previously, an C<undef> process identifier would be interpreted as a
2463 request to kill process 0, which would terminate the current process
2464 group on POSIX systems. Since process identifiers are always integers,
2465 killing a non-numeric process is now fatal.
2469 5.10.0 inadvertently disabled an optimisation, which caused a measurable
2470 performance drop in list assignment, such as is often used to assign
2471 function parameters from C<@_>. The optimisation has been re-instated, and
2472 the performance regression fixed. (This fix is also present in 5.10.1)
2476 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
2480 Some potential coredumps in PerlIO fixed [RT #57322,54828].
2484 The debugger now works with lvalue subroutines.
2488 The debugger's C<m> command was broken on modules that defined constants
2493 C<crypt> and string complement could return tainted values for untainted
2494 arguments [RT #59998].
2498 The C<-i>I<.suffix> command-line switch now recreates the file using
2499 restricted permissions, before changing its mode to match the original
2500 file. This eliminates a potential race condition [RT #60904].
2504 On some Unix systems, the value in C<$?> would not have the top bit set
2505 (C<$? & 128>) even if the child core dumped.
2509 Under some circumstances, C<$^R> could incorrectly become undefined
2514 In the XS API, various hash functions, when passed a pre-computed hash where
2515 the key is UTF-8, might result in an incorrect lookup.
2519 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2524 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
2525 didn't exist, even if the object's C<@ISA> contained C<Foo>.
2529 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2530 C<@ISA>, have been found and fixed.
2534 Bitwise operations on references could crash the interpreter, e.g.
2535 C<$x=\$y; $x |= "foo"> [RT #54956].
2539 Patterns including alternation might be sensitive to the internal UTF-8
2540 representation, e.g.
2542 my $byte = chr(192);
2543 my $utf8 = chr(192); utf8::upgrade($utf8);
2544 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2548 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2549 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2550 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2551 greater than 255 [RT #59908].
2555 C<B::Deparse> failed to correctly deparse various constructs:
2556 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2557 C<sub foo(_)> [RT #62484].
2561 Using C<setpgrp> with no arguments could corrupt the perl stack.
2565 The block form of C<eval> is now specifically trappable by C<Safe> and
2566 C<ops>. Previously it was erroneously treated like string C<eval>.
2570 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2571 match operator (C<~~>) [RT #63854].
2575 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2576 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2578 ("ab" x 32768) =~ /^(ab)*$/
2582 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2586 Using C<next> or C<last> to exit a C<given> block no longer produces a
2587 spurious warning like the following:
2589 Exiting given via last at foo.pl line 123
2593 Assigning a format to a glob could corrupt the format; e.g.:
2595 *bar=*foo{FORMAT}; # foo format now bad
2599 Attempting to coerce a typeglob to a string or number could cause an
2600 assertion failure. The correct error message is now generated,
2601 C<Can't coerce GLOB to I<$type>>.
2605 Under C<use filetest 'access'>, C<-x> was using the wrong access
2606 mode. This has been fixed [RT #49003].
2610 C<length> on a tied scalar that returned a Unicode value would not be
2611 correct the first time. This has been fixed.
2615 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2620 A race condition inside C<PerlIOStdio_close()> has been identified and
2621 fixed. This used to cause various threading issues, including SEGVs.
2625 In C<unpack>, the use of C<()> groups in scalar context was internally
2626 placing a list on the interpreter's stack, which manifested in various
2627 ways, including SEGVs. This is now fixed [RT #50256].
2631 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2632 These have all been fixed.
2636 A 5.10.0 optimisation to clear the temporary stack within the implicit
2637 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2638 obscure bugs in seemingly unrelated parts of the interpreter [commit
2643 The line numbers for warnings inside C<elsif> are now correct.
2647 The C<..> operator now works correctly with ranges whose ends are at or
2648 close to the values of the smallest and largest integers.
2652 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2653 This has been fixed [RT #54828].
2657 An off-by-one error meant that C<index $str, ...> was effectively being
2658 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2662 Various leaks associated with named captures in regexes have been fixed
2667 A weak reference to a hash would leak. This was affecting C<DBI>
2672 Using (?|) in a regex could cause a segfault [RT #59734].
2676 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2680 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2681 unaligned 64-bit access on the SPARC architecture [RT #60574].
2685 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2686 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2691 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2696 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2697 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2702 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2703 missed (method cache issue) [RT #60220,60232].
2707 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2708 cause a memory leak [RT #63110].
2712 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2713 specified on the command line. C<-C> on the shebang line used to be a
2714 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2715 disallowed it, which broke some scripts. Now perl checks whether it is
2716 also on the command line and only dies if it is not [RT #67880].
2720 In 5.10.0, certain types of re-entrant regular expression could crash,
2721 or cause the following assertion failure [RT #60508]:
2723 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2727 Perl now includes previously missing files from the Unicode Character
2732 Perl now honors C<TMPDIR> when opening an anonymous temporary file.
2737 =head1 Platform Specific Changes
2739 Perl is incredibly portable. In general, if a platform has a C compiler,
2740 someone has ported Perl to it (or will soon). We're happy to announce
2741 that Perl 5.12 includes support for several new platforms. At the same
2742 time, it's time to bid farewell to some (very) old friends.
2744 =head2 New Platforms
2750 Perl's developers have merged patches from Haiku's maintainers. Perl
2751 should now build on Haiku.
2755 Perl should now build on MirOS BSD.
2759 =head2 Discontinued Platforms
2771 =head2 Updated Platforms
2781 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
2786 Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
2787 installed. The F<libgdbm> is delivered as an optional package with the
2788 AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
2792 Hints changes mean that AIX 4.2 should work again.
2802 Perl now supports IPv6 on Cygwin 1.7 and newer.
2806 On Cygwin we now strip the last number from the DLL. This has been the
2807 behaviour in the cygwin.com build for years. The hints files have been
2812 =item Darwin (Mac OS X)
2818 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2819 as it's still buggy.
2823 Correct infelicities in the regexp used to identify buggy locales
2824 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2834 Fix thread library selection [perl #69686]
2844 The hints files now identify the correct threading libraries on FreeBSD 7
2855 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2856 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2866 Hints now supports versions 5.*.
2876 C<-UDEBUGGING> is now the default on VMS.
2878 Like it has been everywhere else for ages and ages. Also make command-line
2879 selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
2880 the only way to turn it off was by saying no in answer to the interactive
2885 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2890 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2891 if C<$/> was set to a numeric reference (to indicate record-style reads).
2896 VMS now supports C<getgrgid>.
2900 Many improvements and cleanups have been made to the VMS file name handling
2901 and conversion code.
2905 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2906 status in a VMS condition value for better interaction with GNV's bash
2907 shell and other utilities that depend on POSIX exit values. See
2908 L<perlvms/"$?"> for details.
2912 C<File::Copy> now detects Unix compatibility mode on VMS.
2922 Various changes from Stratus have been merged in.
2932 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2942 Perl 5.12 supports Windows 2000 and later. The supporting code for
2943 legacy versions of Windows is still included, but will be removed
2944 during the next development cycle.
2948 Initial support for building Perl with MinGW-w64 is now available.
2952 F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
2953 settings for Windows Vista and later. Without this setting Windows
2954 would treat F<perl.exe> as a legacy application and apply various
2955 heuristics like redirecting access to protected file system areas
2956 (like the "Program Files" folder) to the users "VirtualStore"
2957 instead of generating a proper "permission denied" error.
2959 The manifest resource also requests the Microsoft Common-Controls
2960 version 6.0 (themed controls introduced in Windows XP). Check out the
2961 Win32::VisualStyles module on CPAN to switch back to old style
2962 unthemed controls for legacy applications.
2966 The C<-t> filetest operator now only returns true if the filehandle
2967 is connected to a console window. In previous versions of Perl it
2968 would return true for all character mode devices, including F<NUL>
2973 The C<-p> filetest operator now works correctly, and the
2974 Fcntl::S_IFIFO constant is defined when Perl is compiled with
2975 Microsoft Visual C. In previous Perl versions C<-p> always
2976 returned a false value, and the Fcntl::S_IFIFO constant
2979 This bug is specific to Microsoft Visual C and never affected
2980 Perl binaries built with MinGW.
2984 The socket error codes are now more widely supported: The POSIX
2985 module will define the symbolic names, like POSIX::EWOULDBLOCK,
2986 and stringification of socket error codes in $! works as well
2989 C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
2990 A non-blocking socket operation could not be completed immediately.
2994 flock() will now set sensible error codes in $!. Previous Perl versions
2995 copied the value of $^E into $!, which caused much confusion.
2999 select() now supports all empty C<fd_set>s more correctly.
3003 C<'.\foo'> and C<'..\foo'> were treated differently than
3004 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
3008 Improved message window handling means that C<alarm> and C<kill> messages
3009 will no longer be dropped under race conditions.
3013 Various bits of Perl's build infrastructure are no longer converted to
3014 win32 line endings at release time. If this hurts you, please report the
3015 problem with the L<perlbug> program included with perl.
3022 =head1 Known Problems
3024 This is a list of some significant unfixed bugs, which are regressions
3025 from either 5.10.x or 5.8.x.
3031 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
3032 (typically introduced by C<my $_> or implicitly by C<given>). The variable
3033 which gets set for each iteration is the package variable C<$_>, not the
3034 lexical C<$_> [RT #67694].
3036 A similar issue may occur in other modules that provide functions which
3037 take a block as their first argument, like
3039 foo { ... $_ ...} list
3043 Some regexes may run much more slowly when run in a child thread compared
3044 with the thread the pattern was compiled into [RT #55600].
3048 Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
3049 will appear to hang as they get into a very long running loop [RT #72998].
3053 Several porters have reported mysterious crashes when Perl's entire
3054 test suite is run after a build on certain Windows 2000 systems. When
3055 run by hand, the individual tests reportedly work fine.
3065 This one is actually a change introduced in 5.10.0, but it was missed
3066 from that release's perldelta, so it is mentioned here instead.
3068 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
3069 in a change of behaviour between 5.8.x and 5.10.0:
3071 # matches in 5.8.x, doesn't match in 5.10.0
3072 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
3076 =head1 Acknowledgements
3078 Perl 5.12.0 represents approximately two years of development since
3079 Perl 5.10.0 and contains over 750,000 lines of changes across over
3080 3,000 files from over 200 authors and committers.
3082 Perl continues to flourish into its third decade thanks to a vibrant
3083 community of users and developers. The following people are known to
3084 have contributed the improvements that became Perl 5.12.0:
3086 Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
3087 Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
3088 Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
3089 andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
3090 Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
3091 Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
3092 Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
3093 Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
3094 Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
3095 Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
3096 David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
3097 Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
3098 Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
3099 Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
3100 Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
3101 Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
3102 Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
3103 Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
3104 Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
3105 John Peacock, John Peacock via RT, John P. Linderman, John Wright,
3106 Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
3107 Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
3108 Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
3109 Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
3110 Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
3111 G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
3112 Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
3113 Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
3114 Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
3115 Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
3116 Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
3117 Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
3118 Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
3119 Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
3120 Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
3121 Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
3122 The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
3123 Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
3124 Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
3125 Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
3127 This is woefully incomplete as it's automatically generated from version
3128 control history. In particular, it doesn't include the names of the
3129 (very much appreciated) contributors who reported issues in previous
3130 versions of Perl that helped make Perl 5.12.0 better. For a more complete
3131 list of all of Perl's historical contributors, please see the C<AUTHORS>
3132 file in the Perl 5.12.0 distribution.
3134 Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
3135 deserve special thanks for their brilliant and substantive ongoing
3136 contributions. Nicholas personally authored over 30% of the patches
3137 since 5.10.0. Rafael comes in second in patch authorship with 11%,
3138 but is first by a long shot in committing patches authored by others,
3139 pushing 44% of the commits since 5.10.0 in this category, often after
3140 providing considerable coaching to the patch authors. These statistics
3141 in no way comprise all of their contributions, but express in shorthand
3142 that we couldn't have done it without them.
3144 Many of the changes included in this version originated in the CPAN
3145 modules included in Perl's core. We're grateful to the entire CPAN
3146 community for helping Perl to flourish.
3148 =head1 Reporting Bugs
3150 If you find what you think is a bug, you might check the articles
3151 recently posted to the comp.lang.perl.misc newsgroup and the perl
3152 bug database at L<http://rt.perl.org/perlbug/>. There may also be
3153 information at L<http://www.perl.org/>, the Perl Home Page.
3155 If you believe you have an unreported bug, please run the B<perlbug>
3156 program included with your release. Be sure to trim your bug down
3157 to a tiny but sufficient test case. Your bug report, along with the
3158 output of C<perl -V>, will be sent off to perlbug@perl.org to be
3159 analyzed by the Perl porting team.
3161 If the bug you are reporting has security implications, which make it
3162 inappropriate to send to a publicly archived mailing list, then please send
3163 it to perl5-security-report@perl.org. This points to a closed subscription
3164 unarchived mailing list, which includes all the core committers, who be able
3165 to help assess the impact of issues, figure out a resolution, and help
3166 co-ordinate the release of patches to mitigate or fix the problem across all
3167 platforms on which Perl is supported. Please only use this address for
3168 security issues in the Perl core, not for modules independently
3169 distributed on CPAN.
3173 The F<Changes> file for an explanation of how to view exhaustive details
3176 The F<INSTALL> file for how to build Perl.
3178 The F<README> file for general stuff.
3180 The F<Artistic> and F<Copying> files for copyright information.
3182 L<http://dev.perl.org/perl5/errata.html> for a list of issues
3183 found after this release, as well as a list of CPAN modules known
3184 to be incompatible with this release.