3 perl5120delta - what is new for perl v5.12.0
5 =head1 XXX - THIS DOCUMENT IS ONLY CURRENT THROUGH PERL5114
11 UPDATED MODULE LIST NEEDS TO BE GENERATED
12 ORDERING NEEDS CHECKING
13 HEAVY COPYEDITING IS NEEDED
18 This document describes differences between the 5.10.0 release and
21 Many of the bug fixes in 5.12.0 were already seen in the 5.10.1
22 maintenance release since the two releases were kept closely
23 coordinated (while 5.12.0 was still called 5.11.something).
25 You can see the list of changes in the 5.10.1 release
26 by reading L<perl5101delta>.
28 =head1 Core Enhancements
32 It is now possible to overload the C<qr//> operator, that is,
33 conversion to regexp, like it was already possible to overload
34 conversion to boolean, string or number of objects. It is invoked when
35 an object appears on the right hand side of the C<=~> operator or when
36 it is interpolated into a regexp. See L<overload>.
38 =head2 Pluggable keywords
40 Extension modules can now cleanly hook into the Perl parser to define
41 new kinds of keyword-headed expression and compound statement. The
42 syntax following the keyword is defined entirely by the extension. This
43 allow a completely non-Perl sublanguage to be parsed inline, with the
44 correct ops cleanly generated. This feature is currently considered
47 See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core
48 source distribution also includes a new module
49 L<XS::APItest::KeywordRPN>, which implements reverse Polish notation
50 arithmetic via pluggable keywords. This module is mainly used for test
51 purposes, and is not normally installed, but also serves as an example
52 of how to use the new mechanism.
54 =head2 APIs for more internals
56 The lowest layers of the lexer and parts of the pad system now have C
57 APIs available to XS extensions. These are necessary to support proper
58 use of pluggable keywords, but have other uses too. The new APIs are
59 experimental, and only cover a small proportion of what would be
60 necessary to take full advantage of the core's facilities in these
61 areas. It is intended that the Perl 5.13 development cycle will see the
62 addition of a full range of clean, supported interfaces.
64 =head2 Overridable function lookup
66 Where an extension module hooks the creation of rv2cv ops to modify the
67 subroutine lookup process, this now works correctly for bareword
68 subroutine calls. This means that prototypes on subroutines referenced
69 this way will be processed correctly. (Previously bareword subroutine
70 names were initially looked up, for parsing purposes, by an unhookable
71 mechanism, so extensions could only properly influence subroutine names
72 that appeared with an C<&> sigil.)
74 =head2 Unicode version
76 Perl is shipped with the latest Unicode version, 5.2, dated October 2009. See
77 L<http://www.unicode.org/versions/Unicode5.2.0> for details about this release
78 of Unicode. See L<perlunicode> for instructions on installing and using
79 older versions of Unicode.
81 =head2 Unicode properties
83 A concerted effort has been made to update Perl to be in sync with the latest
84 Unicode standard. Changes for this include:
86 Perl can now handle every Unicode character property. A new pod,
87 L<perluniprops>, lists all available non-Unihan character properties. By
88 default the Unihan properties and certain others (deprecated and Unicode
89 internal-only ones) are not exposed. See below for more details on
90 these; there is also a section in the pod listing them, and explaining
91 why they are not exposed.
93 Perl now fully supports the Unicode compound-style of using C<=> and C<:>
94 in writing regular expressions: C<\p{property=value}> and
95 C<\p{property:value}> (both of which mean the same thing).
97 Perl now fully supports the Unicode loose matching rules for text
98 between the braces in C<\p{...}> constructs. In addition, Perl allows
99 underscores between digits of numbers.
101 All the Unicode-defined synonyms for properties and property values are
104 C<qr/\X/>, which matches a Unicode logical character, has been expanded to work
105 better with various Asian languages. It now is defined as an I<extended
106 grapheme cluster>. (See L<http://www.unicode.org/reports/tr29/>).
107 Anything matched previously and that made sense will continue to be
108 matched, but in addition:
114 C<\X> will not break apart a C<S<CR LF>> sequence.
118 C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ> characters.
122 C<\X> will now always match at least one character, including an initial mark.
123 Marks generally come after a base character, but it is possible in Unicode to
124 have them in isolation, and C<\X> will now handle that case, for example at the
125 beginning of a line, or after a C<ZWSP>. And this is the part where C<\X>
126 doesn't match the things that it used to that don't make sense. Formerly, for
127 example, you could have the nonsensical case of an accented LF.
131 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai and Lao
136 Otherwise, this change should be transparent for the non-affected languages.
138 C<\p{...}> matches using the Canonical_Combining_Class property were
139 completely broken in previous Perls. This is now fixed.
141 In previous Perls, the Unicode C<Decomposition_Type=Compat> property and a
142 Perl extension had the same name, which led to neither matching all the
143 correct values (with more than 100 mistakes in one, and several thousand
144 in the other). The Perl extension has now been renamed to be
145 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the same
146 meaning as was previously intended, namely the union of all the
147 non-canonical Decomposition types, with Unicode C<Compat> being just one of
150 C<\p{Uppercase}> and C<\p{Lowercase}> have been brought into line with the
151 Unicode definitions. This means they each match a few more characters
154 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This means it
155 no longer will match Private Use (gc=co), Surrogates (gc=cs), nor Format
156 (gc=cf) code points. The Format code points represent the biggest
157 possible problem. All but 36 of them are either officially deprecated
158 or strongly discouraged from being used. Of those 36, likely the most
159 widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ, WJ, and
160 similar characters, plus bidirectional controls.
162 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. The Perl
163 definition included a number of things that aren't really alpha (all
164 marks), while omitting many that were. As a direct consequence, the
165 definitions of C<\p{Alnum}> and C<\p{Word}> which depend on Alpha also change
168 C<\p{Word}> also now doesn't match certain characters it wasn't supposed
169 to, such as fractions.
171 C<\p{Print}> no longer matches the line control characters: Tab, LF, CR,
172 FF, VT, and NEL. This brings it in line with standards and the documentation.
174 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
176 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
177 means that in addition to the characters it currently matches,
178 C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
179 example U+FF10: FULLWIDTH DIGIT ZERO.
181 The Numeric type property has been extended to include the Unihan
184 There is a new Perl extension, the 'Present_In', or simply 'In',
185 property. This is an extension of the Unicode Age property, but
186 C<\p{In=5.0}> matches any code point whose usage has been determined
187 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
188 added in I<precisely> version 5.0.
190 A number of properties did not have the correct values for unassigned
191 code points. This is now fixed. The affected properties are
192 Bidi_Class, East_Asian_Width, Joining_Type, Decomposition_Type,
193 Hangul_Syllable_Type, Numeric_Type, and Line_Break.
195 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
196 have been updated to their current Unicode definitions.
198 Certain properties that are supposed to be Unicode internal-only were
199 erroneously exposed by previous Perls. Use of these in regular
200 expressions will now generate, if enabled, a deprecated warning message.
201 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
202 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
203 Other_Math, and Other_Uppercase.
205 An installation can now fairly easily change which Unicode properties
206 Perl understands. As mentioned above, certain properties are by default
207 turned off. These include all the Unihan properties (which should be
208 accessible via the CPAN module Unicode::Unihan) and any deprecated or
209 Unicode internal-only property that Perl has never exposed.
211 The generated files in the C<lib/unicore/To> directory are now more
212 clearly marked as being stable, directly usable by applications.
213 New hash entries in them give the format of the normal entries,
214 which allows for easier machine parsing. Perl can generate files
215 in this directory for any property, though most are suppressed. An
216 installation can choose to change which get written. Instructions
217 are in L<perluniprops>.
219 =head2 Regular Expressions
221 U+0FFFF is now a legal character in regular expressions.
223 =head2 A proper interface for pluggable Method Resolution Orders
225 As of Perl 5.11.0 there is a new interface for plugging and using method
226 resolution orders other than the default (linear depth first search).
227 The C3 method resolution order added in 5.10.0 has been re-implemented as
228 a plugin, without changing its Perl-space interface. See L<perlmroapi> for
231 =head2 The C<overloading> pragma
233 This pragma allows you to lexically disable or enable overloading
234 for some or all operations. (Yuval Kogman)
236 =head2 C<\N> regex escape
238 A new regex escape has been added, C<\N>. It will match any character that
239 is not a newline, independently from the presence or absence of the single
240 line match modifier C</s>. (If C<\N> is followed by an opening brace and
241 by a letter, perl will still assume that a Unicode character name is
242 coming, so compatibility is preserved.) (Rafael Garcia-Suarez)
244 This will break a L<custom charnames translator|charnames/CUSTOM TRANSLATORS>
245 which allows numbers for character names, as C<\N{3}> will now mean to match 3
246 non-newline characters, and not the character whose name is C<3>. (No standard
247 name is a number, so only a custom translator would be affected.)
249 =head2 Implicit strictures
251 Using the C<use VERSION> syntax with a version number greater or equal
252 to 5.11.0 will also lexically enable strictures just like C<use strict>
253 would do (in addition to enabling features.) So, the following:
262 =head2 Parallel tests
264 The core distribution can now run its regression tests in parallel on
265 Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
266 your environment to the number of tests to run in parallel, and run
267 C<make test_harness>. On a Bourne-like shell, this can be done as
269 TEST_JOBS=3 make test_harness # Run 3 tests in parallel
271 An environment variable is used, rather than parallel make itself, because
272 L<TAP::Harness> needs to be able to schedule individual non-conflicting test
273 scripts itself, and there is no standard interface to C<make> utilities to
274 interact with their job schedulers.
276 Note that currently some test scripts may fail when run in parallel (most
277 notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
278 again sequentially and see if the failures go away.
280 =head2 The C<...> operator
282 A new operator, C<...>, nicknamed the Yada Yada operator, has been added.
283 It is intended to mark placeholder code that is not yet implemented.
284 See L<perlop/"Yada Yada Operator">. (chromatic)
286 =head2 DTrace support
288 Some support for DTrace has been added. See "DTrace support" in F<INSTALL>.
290 =head2 Support for C<configure_requires> in CPAN module metadata
292 Both C<CPAN> and C<CPANPLUS> now support the C<configure_requires> keyword
293 in the F<META.yml> metadata file included in most recent CPAN distributions.
294 This allows distribution authors to specify configuration prerequisites that
295 must be installed before running F<Makefile.PL> or F<Build.PL>.
297 See the documentation for C<ExtUtils::MakeMaker> or C<Module::Build> for more
298 on how to specify C<configure_requires> when creating a distribution for CPAN.
300 =head2 C<each> is now more flexible
302 The C<each> function can now operate on arrays.
304 =head2 Y2038 compliance
306 Perl's core time-related functions are now Y2038 compliant. (With 29
309 =head2 C<$,> flexibility
311 The variable C<$,> may now be tied.
313 =head2 // in where clauses
315 // now behaves like || in when clauses
317 =head2 Enabling warnings from your shell environment
319 You can now set C<-W> from the C<PERL5OPT> environment variable
321 =head2 C<delete local>
323 C<delete local> now allows you to locally delete a hash entry.
325 =head2 New support for Abstract namespace sockets
327 Abstract namespace sockets are Linux-specific socket type that live in
328 AF_UNIX family, slightly abusing it to be able to use arbitrary
329 character arrays as addresses: They start with nul byte and are not
330 terminated by nul byte, but with the length passed to the socket()
333 =head2 New C<package NAME VERSION> syntax
335 This new syntax allows a module author to set the $VERSION of a namespace
336 when the namespace is declared with 'package'. It eliminates the need
337 for C<our $VERSION = ...> and similar constructs. E.g.
339 package Foo::Bar 1.23;
340 # $Foo::Bar::VERSION == 1.23
342 There are several advantages to this:
348 C<$VERSION> is parsed in exactly the same way as C<use NAME VERSION>
352 C<$VERSION> is set at compile time
356 C<$VERSION> is a version object that provides proper overloading of
357 comparision operators so comparing C<$VERSION> to decimal (1.23) or
358 dotted-decimal (v1.2.3) version numbers works correctly.
362 Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
366 As it requires VERSION to be a numeric literal or v-string
367 literal, it can be statically parsed by toolchain modules
368 without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
372 It does not break old code with only C<package NAME>, but code that uses
373 C<package NAME VERSION> will need to be restricted to perl 5.12.0 or newer
374 This is analogous to the change to C<open> from two-args to three-args.
375 Users requiring the latest Perl will benefit, and perhaps after several
376 years, it will become a standard practice.
380 However, C<package NAME VERSION> requires a new, 'strict' version
381 number format. See L<"Version number formats"> for details.
383 =head1 Incompatible Changes
385 =head2 Version number formats
387 Acceptable version number formats have been formalized into "strict" and
388 "lax" rules. C<package NAME VERSION> takes a strict version number. C<use
389 NAME VERSION> takes a lax version number. C<UNIVERSAL::VERSION> and the
390 L<version> object constructors take lax version numbers. Providing an
391 invalid version will result in a fatal error.
393 These formats will be documented fully in the L<version> module in a
394 subsequent release of Perl 5.11. To a first approximation, a "strict"
395 version number is a positive decimal number (integer or decimal-fraction)
396 without exponentiation or else a dotted-decimal v-string with a leading 'v'
397 character and at least three components. A "lax" version number allows
398 v-strings with fewer than three components or without a leading 'v'. Under
399 "lax" rules, both decimal and dotted-decimal versions may have a trailing
400 "alpha" component separated by an underscore character after a fractional
401 or dotted-decimal component.
403 The L<version> module adds C<version::is_strict> and C<version::is_lax>
404 functions to check a scalar against these rules.
406 =head2 @INC reorganization
408 In @INC, ARCHLIB and PRIVLIB now occur after after the current version's
409 site_perl and vendor_perl.
411 =head2 Switch statement changes
413 The handling of complex expressions by the C<given>/C<when> switch
414 statement has been enhanced. These enhancements are also available in
415 5.10.1 and subsequent 5.10 releases. There are two new cases where
416 C<when> now interprets its argument as a boolean, instead of an
417 expression to be used in a smart match:
419 =head2 flip-flop operators
421 The C<..> and C<...> flip-flop operators are now evaluated in boolean
422 context, following their usual semantics; see L<perlop/"Range Operators">.
424 Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
425 whether a given value is an integer between 1 and 10; you should use
426 C<when ([1..10])> instead (note the array reference).
428 However, contrary to 5.10.0, evaluating the flip-flop operators in boolean
429 context ensures it can now be useful in a C<when()>, notably for
430 implementing bistable conditions, like in:
432 when (/^=begin/ .. /^=end/) {
436 =head2 defined-or operator
438 A compound expression involving the defined-or operator, as in
439 C<when (expr1 // expr2)>, will be treated as boolean if the first
440 expression is boolean. (This just extends the existing rule that applies
441 to the regular or operator, as in C<when (expr1 || expr2)>.)
443 =head2 Smart match changes
445 This section details more changes brought to the semantics to
446 the smart match operator, that naturally also modify the behaviour
447 of the switch statements where smart matching is implicitly used.
448 These changes were also made for the 5.10.1 release, and will remain in
449 subsequent 5.10 releases.
451 =head3 Changes to type-based dispatch
453 The smart match operator C<~~> is no longer commutative. The behaviour of
454 a smart match now depends primarily on the type of its right hand
455 argument. Moreover, its semantics have been adjusted for greater
456 consistency or usefulness in several cases. While the general backwards
457 compatibility is maintained, several changes must be noted:
463 Code references with an empty prototype are no longer treated specially.
464 They are passed an argument like the other code references (even if they
465 choose to ignore it).
469 C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
470 returns a true value for each key of the hash (or element of the
471 array), instead of passing the whole hash or array as a reference to
476 Due to the commutativity breakage, code references are no longer
477 treated specially when appearing on the left of the C<~~> operator,
478 but like any vulgar scalar.
482 C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
483 hash). No implicit conversion to C<""> is done (as was the case in perl
488 C<$scalar ~~ @array> now always distributes the smart match across the
489 elements of the array. It's true if one element in @array verifies
490 C<$scalar ~~ $element>. This is a generalization of the old behaviour
491 that tested whether the array contained the scalar.
495 The full dispatch table for the smart match operator is given in
496 L<perlsyn/"Smart matching in detail">.
498 =head3 Smart match and overloading
500 According to the rule of dispatch based on the rightmost argument type,
501 when an object overloading C<~~> appears on the right side of the
502 operator, the overload routine will always be called (with a 3rd argument
503 set to a true value, see L<overload>.) However, when the object will
504 appear on the left, the overload routine will be called only when the
505 rightmost argument is a simple scalar. This way, distributivity of smart
506 match across arrays is not broken, as well as the other behaviours with
507 complex types (coderefs, hashes, regexes). Thus, writers of overloading
508 routines for smart match mostly need to worry only with comparing
509 against a scalar, and possibly with stringification overloading; the
510 other common cases will be automatically handled consistently.
512 C<~~> will now refuse to work on objects that do not overload it (in order
513 to avoid relying on the object's underlying structure). (However, if the
514 object overloads the stringification or the numification operators, and
515 if overload fallback is active, it will be used instead, as usual.)
517 =head2 Labels can't be keywords
519 Labels used as targets for the C<goto>, C<last>, C<next> or C<redo>
520 statements cannot be keywords anymore. This restriction will prevent
521 potential confusion between the C<goto LABEL> and C<goto EXPR> syntaxes:
522 for example, a statement like C<goto print> would jump to a label whose
523 name would be the return value of C<print()>, (usually 1), instead of a
524 label named C<print>. Moreover, the other control flow statements
525 would just ignore any keyword passed to them as a label name. Since
526 such labels cannot be defined anymore, this kind of error will be
529 =head2 Other incompatible changes
535 The definitions of a number of Unicode properties have changed to match those
536 of the current Unicode standard. These are listed above under L</Unicode
537 properties>. This could break code that is expecting the old definitions.
541 The boolkeys op moved to the group of hash ops. This breaks binary
546 Filehandles are blessed directly into C<IO::Handle>, as C<FileHandle> is
547 merely a wrapper around C<IO::Handle>.
549 The previous behaviour was to bless Filehandles into L<FileHandle>
550 (an empty proxy class) if it was loaded into memory and otherwise
551 to bless them into C<IO::Handle>.
555 The semantics of C<use feature :5.10*> have changed slightly.
556 See L<"Modules and Pragmata"> for more information.
560 The version control system used for the development of the perl
561 interpreter has been switched from Perforce to git. This is mainly an
562 internal issue that only affects people actively working on the perl core;
563 but it may have minor external visibility, for example in some of details
564 of the output of C<perl -V>. See L<perlrepository> for more information.
568 The internal structure of the C<ext/> directory in the perl source has
569 been reorganised. In general, a module C<Foo::Bar> whose source was
570 stored under F<ext/Foo/Bar/> is now located under F<ext/Foo-Bar/>. Also,
571 nearly all dual-life modules have been moved from F<lib/> to F<ext/>. This
572 is purely a source tarball change, and should make no difference to the
573 compilation or installation of perl, unless you have a very customised build
574 process that explicitly relies on this structure, or which hard-codes the
575 C<nonxs_ext> F<Configure> parameter. Specifically, this change does not by
576 default alter the location of any files in the final installation.
580 As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
581 C<Test::Harness::Straps> module has been removed.
582 See L</"Updated Modules"> for more details.
586 As part of the C<ExtUtils::MakeMaker> upgrade, the
587 C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
588 have been removed from this distribution.
592 C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
596 This one is actually a change introduced in 5.10.0, but it was missed
597 from that release's perldelta, so it is mentioned here instead.
599 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
600 in a change of behaviour between 5.8.x and 5.10.0:
602 # matches in 5.8.x, doesn't match in 5.10.0
603 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
607 C<length undef> now returns undef.
611 Unsupported private C API functions are now declared "static" to prevent
612 leakage to Perl's public API.
616 To support the bootstrapping process, F<miniperl> no longer builds with
617 UTF-8 support in the regexp engine.
619 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
620 Without this there's a bootstrapping problem, as miniperl can't load the UTF-8
621 components of the regexp engine, because they're not yet built.
625 F<miniperl>'s @INC is now restricted to just C<-I...>, the split of
626 C<$ENV{PERL5LIB}>, and "C<.>"
630 A space or a newline is now required after a C<"#line XXX"> directive.
634 Tied filehandles now have an additional method EOF which provides the EOF type
638 To better match all other flow control statements, C<foreach> may no
639 longer be used as an attribute.
645 From time to time, Perl's developers find it necessary to deprecate
646 features or modules we've previously shipped as part of the core
647 distribution. We are well aware of the pain and frustration that a
648 backwards-incompatible change to Perl can cause for developers building
649 or maintaining software in Perl. You can be sure that when we deprecate
650 a functionality or syntax, it isn't a choice we make lightly. Sometimes,
651 we choose to deprecate functionality or syntax because it was found to
652 be poorly designed or implemented. Sometimes, this is because they're
653 holding back other features or causing performance problems. Sometimes,
654 the reasons are more complex. Wherever possible, we try to keep deprecated
655 functionality available to developers in its previous form for at least
656 one major release. So long as a deprecated feature isn't actively
657 disrupting our ability to maintain and extend Perl, we'll try to leave
658 it in place as long as possible.
660 The following items are now deprecated.
664 =item Use of C<:=> to mean an empty attribute list is now deprecated.
666 An accident of Perl's parser meant that these constructions were all
673 with the C<:> being treated as the start of an attribute list, which
674 ends before the C<=>. As whitespace is not significant here, all are
675 parsed as an empty attribute list, hence all the above are equivalent
676 to, and better written as
680 because no attribute processing is done for an empty list.
682 As is, this meant that C<:=> cannot be used as a new token, without
683 silently changing the meaning of existing code. Hence that particular
684 form is now deprecated, and will become a syntax error. If it is
685 absolutely necessary to have empty attribute lists (for example,
686 because of a code generator) then avoid the warning by adding a space
689 =item C<< UNIVERSAL->import() >>
691 The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
692 pass import arguments to a C<use UNIVERSAL> statement will result in a
695 =item Use of "goto" to jump into a construct is deprecated
697 Using C<goto> to jump from an outer scope into an inner scope is now
698 deprecated. This rare use case was causing problems in the
699 implementation of scopes.
701 =item Deprecated Modules
703 The following modules will be removed from the core distribution in a future
704 release, and should be installed from CPAN instead. Distributions on CPAN
705 which require these should add them to their prerequisites. The core versions
706 of these modules warnings will issue a deprecation warning.
712 =item L<Pod::Plainer>
718 Switch is buggy and should be avoided. See L<perlsyn/"Switch
719 statements"> for its replacement.
725 C<suidperl> has been removed. It used to provide a mechanism to
726 emulate setuid permission bits on systems that don't support it properly.
728 =item Assignment to $[
732 Remove attrs, which has been deprecated since 1999-10-02.
734 =item Use of the attribute :locked on subroutines.
736 =item Use of "locked" with the attributes pragma.
738 =item Use of "unique" with the attributes pragma.
740 =item Numerous Perl 4-era libraries:
742 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
743 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
744 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
745 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
746 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
747 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
748 F<timelocal.pl> are all now deprecated. Using them will incur a warning.
752 =head1 Modules and Pragmata
754 =head2 Dual-lifed modules moved
756 Dual-lifed modules maintained primarily in the Perl core now live in dist/.
757 Dual-lifed modules maintained primarily on CPAN now live in cpan/
759 In previous releases of Perl, it was customary to enumerate all module
760 changes in this section of the C<perldelta> file. From 5.11.0 forward
761 only notable updates (such as new or deprecated modules ) will be listed
762 in this section. For a complete reference to the versions of modules
763 shipped in a given release of perl, please see L<Module::CoreList>.
765 =head2 New Modules and Pragmata
773 This is a new lexically-scoped alternative for the C<Fatal> module.
774 The bundled version is 2.06_01. Note that in this release, using a string
775 eval when C<autodie> is in effect can cause the autodie behaviour to leak
776 into the surrounding scope. See L<autodie/"BUGS"> for more details.
780 C<Compress::Raw::Bzip2>
782 This has been added to the core (version 2.020).
788 This pragma establishes an ISA relationship with base classes at compile
789 time. It provides the key feature of C<base> without further unwanted
796 This has been added to the core (version 1.39).
800 =head2 Pragmata Changes
808 See L</"The C<overloading> pragma"> above.
814 The C<attrs> pragma has been removed. It had been marked as deprecated since
821 The Unicode F<NameAliases.txt> database file has been added. This has the
822 effect of adding some extra C<\N> character names that formerly wouldn't
823 have been recognised; for example, C<"\N{LATIN CAPITAL LETTER GHA}">.
829 The meaning of the C<:5.10> and C<:5.10.X> feature bundles has
830 changed slightly. The last component, if any (i.e. C<X>) is simply ignored.
831 This is predicated on the assumption that new features will not, in
832 general, be added to maintenance releases. So C<:5.10> and C<:5.10.X>
833 have identical effect. This is a change to the behaviour documented for
840 Upgraded from version 1.00 to 1.01. Performance for single inheritance is 40%
841 faster - see L</"Performance Enhancements"> below.
843 C<mro> is now implemented as an XS extension. The documented interface has not
844 changed. Code relying on the implementation detail that some C<mro::>
845 methods happened to be available at all times gets to "keep both pieces".
851 Supports %.0f formatting internally.
857 Allow overloading of 'qr'.
863 Upgraded from version 1.19 to 1.20.
869 This pragma no longer suppresses C<Use of uninitialized value in range
870 (or flip)> warnings. [perl #71204]
876 Upgraded from 1.13 to 1.14. Added the C<unicode_strings> feature:
878 use feature "unicode_strings";
880 This pragma turns on Unicode semantics for the case-changing operations
881 (C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
882 internal UTF-8 flag set, but that contain single-byte characters between
889 Upgraded from version 1.74 to 1.75.
895 Upgraded from version 0.02 to 0.03.
897 This version introduces the C<stash_name> method to allow subclasses of
898 C<less> to pick where in %^H to store their stash.
904 Upgraded from version 0.77 to 0.81.
906 This version adds support for L</Version number formats> as described earlier
907 in this document and in its own documentation.
913 Upgraded from 1.07 to 1.09.
915 Added new C<warnings::fatal_enabled()> function.
916 This version adds the C<illegalproto> warning category. See also L</New or
917 Changed Diagnostics> for this change.
922 =head2 Updated Modules
926 =item XXX TODO RECALCULATE THIS VS 5.10.0
930 =head2 Removed Modules and Pragmata
938 Removed from the Perl core. Prior version was 'undef'.
944 =head2 New Documentation
952 This contains instructions on how to build perl for the Haiku platform.
958 This describes the new interface for pluggable Method Resolution Orders.
964 This document, by Richard Foley, provides an introduction to the use of
965 performance and optimization techniques which can be used with particular
966 reference to perl programs.
972 This describes how to access the perl source using the I<git> version
977 L<perlpolicy> extends the "Social contract about contributed modules" into
978 the beginnings of a document on Perl porting policies.
982 =head2 Changes to Existing Documentation
984 The various large F<Changes*> files (which listed every change made to perl
985 over the last 18 years) have been removed, and replaced by a small file,
986 also called F<Changes>, which just explains how that same information may
987 be extracted from the git version control system.
989 The file F<Porting/patching.pod> has been deleted, as it mainly described
990 interacting with the old Perforce-based repository, which is now obsolete.
991 Information still relevant has been moved to L<perlrepository>.
993 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
994 generated at build time, rather than being shipped as part of the release.
1000 Documented -X overloading.
1004 Documented that C<when()> treats specially most of the filetest operators
1008 Documented C<when> as a syntax modifier
1012 Eliminated "Old Perl threads tutorial", which described 5005 threads.
1014 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1018 Correct previous documentation: v-strings are not deprecated
1020 With version objects, we need them to use MODULE VERSION syntax. This
1021 patch removes the deprecation notice.
1025 Added security contact information to L<perlsec>
1027 A significant fraction of the core documentation has been updated to clarify
1028 the behavior of Perl's Unicode handling.
1030 Much of the remaining core documentation has been reviewed and edited
1031 for clarity, consistent use of language, and to fix the spelling of Tom
1032 Christiansen's name.
1034 The Pod specification (L<perlpodspec>) has been updated to bring the
1035 specification in line with modern usage already supported by most Pod
1036 systems. A parameter string may now follow the format name in a
1037 "begin/end" region. Links to URIs with a text description are now
1038 allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
1041 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1042 conditional loading of modules despite the implicit BEGIN block around
1047 The documentation for C<$1> in perlvar.pod has been clarified.
1051 =head1 Performance Enhancements
1057 A new internal cache means that C<isa()> will often be faster.
1061 The implementation of C<C3> Method Resolution Order has been optimised -
1062 linearisation for classes with single inheritance is 40% faster. Performance
1063 for multiple inheritance is unchanged.
1067 Under C<use locale>, the locale-relevant information is now cached on
1068 read-only values, such as the list returned by C<keys %hash>. This makes
1069 operations such as C<sort keys %hash> in the scope of C<use locale> much
1074 Empty C<DESTROY> methods are no longer called.
1078 Faster C<Perl_sv_utf8_upgrade()>
1082 Speed up C<keys> on empty hash
1086 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>
1090 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1091 now happens in-place and is several orders of magnitude faster than it
1092 used to be. It will also preserve non-existent elements whenever
1093 possible, i.e. for non magical arrays or tied arrays with C<EXISTS> and
1098 =head1 Installation and Configuration Improvements
1100 =head2 F<ext/> reorganisation
1102 The layout of directories in F<ext> has been revised. Specifically, all
1103 extensions are now flat, and at the top level, with C</> in pathnames
1104 replaced by C<->, so that F<ext/Data/Dumper/> is now F<ext/Data-Dumper/>,
1105 etc. The names of the extensions as specified to F<Configure>, and as
1106 reported by C<%Config::Config> under the keys C<dynamic_ext>,
1107 C<known_extensions>, C<nonxs_ext> and C<static_ext> have not changed, and
1108 still use C</>. Hence this change will not have any affect once perl is
1109 installed. C<Safe> has been split out from being part of C<Opcode>, and
1110 C<mro> is now an extension in its own right.
1112 Nearly all dual-life modules have been moved from F<lib> to F<ext>, and will
1113 now appear as known C<nonxs_ext>. This will made no difference to the
1114 structure of an installed perl, nor will the modules installed differ,
1115 unless you run F<Configure> with options to specify an exact list of
1116 extensions to build. In this case, you will rapidly become aware that you
1117 need to add to your list, because various modules needed to complete the
1118 build, such as C<ExtUtils::ParseXS>, have now become extensions, and
1119 without them the build will fail well before it attempts to run the
1122 =head2 Configuration improvements
1124 If C<vendorlib> and C<vendorarch> are the same, then they are only added to
1127 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1128 perl is built with C<-Dusedevel>.
1130 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1131 against stack-smashing attacks, if the compiler supports it.
1133 F<Configure> will now determine the correct prototypes for re-entrant
1134 functions and for C<gconvert> if you are using a C++ compiler rather
1137 On Unix, if you build from a tree containing a git repository, the
1138 configuration process will note the commit hash you have checked out, for
1139 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1140 are automatically added to the list of local patches displayed by
1143 USE_ATTRIBUTES_FOR_PERLIO is now reported in the compile-time options
1144 listed by the C<-V> switch.
1146 =head2 Compilation improvements
1148 As part of the flattening of F<ext>, all extensions on all platforms are
1149 built by F<make_ext.pl>. This replaces the Unix-specific
1150 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1151 F<win32/buildext.pl>.
1153 =head1 Changed Internals
1159 C<Perl_pmflag> has been removed from the public API. Calling it now
1160 generates a deprecation warning, and it will be removed in a future
1161 release. Although listed as part of the API, it was never documented,
1162 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
1163 core, it has been replaced by a static function.
1167 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1171 TODO: C<SVt_RV> is gone. RVs are now stored in IVs
1175 TODO: REGEXPs are first class
1179 TODO: OOK is reworked, such that an OOKed scalar is PV not PVIV
1183 The J.R.R. Tolkien quotes at the head of C source file have been checked and
1184 proper citations added, thanks to a patch from Tom Christiansen.
1188 C<Perl_vcroak()> now accepts a null first argument. In addition, a full audit
1189 was made of the "not NULL" compiler annotations, and those for several
1190 other internal functions were corrected.
1194 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1195 have been added to formalise the temporary saving of the C<errno>
1200 The function C<Perl_sv_insert_flags> has been added to augment
1205 The function C<Perl_newSV_type(type)> has been added, equivalent to
1206 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1210 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1211 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1213 Two flag bits are currently supported.
1221 This will call C<SvUTF8_on()> for you. (Note that this does not convert an
1222 sequence of ISO 8859-1 characters to UTF-8). A wrapper, C<newSVpvn_utf8()>
1223 is available for this.
1229 Call C<Perl_sv_2mortal()> on the new SV.
1233 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1237 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1242 The functions C<PerlIO_find_layer> and C<PerlIO_list_alloc> are now
1247 C<PL_na> has been exterminated from the core code, replaced by local STRLEN
1248 temporaries, or C<*_nolen()> calls. Either approach is faster than C<PL_na>,
1249 which is a pointer dereference into the interpreter structure under ithreads,
1250 and a global variable otherwise.
1254 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()> on
1255 the scalar. It now updates the linked list to remove each piece of magic
1260 Under ithreads, the regex in C<PL_reg_curpm> is now reference counted. This
1261 eliminates a lot of hackish workarounds to cope with it not being reference
1266 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1267 This has been fixed.
1271 The I<public> IV and NV flags are now not set if the string value has
1272 trailing "garbage". This behaviour is consistent with not setting the
1273 public IV or NV flags if the value is out of range for the type.
1277 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
1278 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
1279 that was enabled when the F<perl> binary was compiled.
1283 Smartmatch resolution tracing has been added as a new diagnostic. Use C<-DM> to
1288 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
1289 C<-Dx> for its original purpose of dumping syntax trees.
1293 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have been
1294 replaced by C<NULL> in the core code, and non-dual-life modules, as C<NULL>
1295 is clearer to those unfamiliar with the core code.
1299 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1300 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1301 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1302 casting away C<const>. This allows proper compile-time auditing of
1303 C<const> correctness in the core, and helped picked up some errors (now
1308 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1309 stack and mortalizing them.
1313 Use of the private structure C<mro_meta> has changed slightly. Nothing
1314 outside the core should be accessing this directly anyway.
1318 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1319 to view how a C preprocessor macro would be expanded when compiled.
1320 This is handy when trying to decode the macro hell that is the perl
1329 Many modules updated from CPAN incorporate new tests.
1330 Several tests that have the potential to hang forever if they fail now
1331 incorporate a "watchdog" functionality that will kill them after a timeout,
1332 which helps ensure that C<make test> and C<make test_harness> run to
1333 completion automatically. (Jerry Hedden).
1335 Some core-specific tests have been added:
1341 Significant cleanups to core tests to ensure that language and
1342 interpreter features are not used before they're tested.
1346 C<make test_porting> now runs a number of important pre-commit checks
1347 which might be of use to anyone working on the Perl core.
1351 F<t/porting/podcheck.t> automatically checks the well-formedness of
1352 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1353 dual-lifed modules which are primarily maintained outside the Perl core.
1357 F<t/porting/manifest.t> now tests that all files listed in MANIFEST are present.
1361 F<t/op/while_readdir.t>
1363 Test that a bare readdir in while loop sets $_.
1367 F<t/comp/retainedlines.t>
1369 Check that the debugger can retain source lines from C<eval>.
1373 F<t/io/perlio_fail.t>
1375 Check that bad layers fail.
1379 F<t/io/perlio_leaks.t>
1381 Check that PerlIO layers are not leaking.
1385 F<t/io/perlio_open.t>
1387 Check that certain special forms of open work.
1393 General PerlIO tests.
1399 Check that there is no unexpected interaction between the internal types
1400 C<PVBM> and C<PVGV>.
1404 F<t/mro/package_aliases.t>
1406 Check that mro works properly in the presence of aliased packages.
1412 Tests for C<dbmopen> and C<dbmclose>.
1418 Tests for the interaction of C<index> and threads.
1424 Tests for the interaction of esoteric patterns and threads.
1430 Test that C<qr> doesn't leak.
1434 F<t/op/reg_email_thr.t>
1436 Tests for the interaction of regex recursion and threads.
1440 F<t/op/regexp_qr_embed_thr.t>
1442 Tests for the interaction of patterns with embedded C<qr//> and threads.
1446 F<t/op/regexp_unicode_prop.t>
1448 Tests for Unicode properties in regular expressions.
1452 F<t/op/regexp_unicode_prop_thr.t>
1454 Tests for the interaction of Unicode properties and threads.
1458 F<t/op/reg_nc_tie.t>
1460 Test the tied methods of C<Tie::Hash::NamedCapture>.
1464 F<t/op/reg_posixcc.t>
1466 Check that POSIX character classes behave consistently.
1472 Check that exportable C<re> functions in F<universal.c> work.
1476 F<t/op/setpgrpstack.t>
1478 Check that C<setpgrp> works.
1482 F<t/op/substr_thr.t>
1484 Tests for the interaction of C<substr> and threads.
1490 Check that upgrading and assigning scalars works.
1496 Check that Unicode in the lexer works.
1502 Check that Unicode and C<tie> work.
1506 F<t/comp/final_line_num.t>
1508 See if line numbers are correct at EOF
1512 F<t/comp/form_scope.t>
1514 See if format scoping works
1518 F<t/comp/line_debug.t>
1520 See if C<< @{"_<$file"} >> works
1524 F<t/op/filetest_t.t>
1526 See if -t file test works
1538 Tests malfunctions of utf8 cache
1544 Test unicode \p{} regex constructs
1548 =head2 Testing improvements
1554 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1559 =head1 New or Changed Diagnostics
1561 Several new diagnostics, see L<perldiag> for details.
1567 C<Bad plugin affecting keyword '%s'>
1571 C<gmtime(%.0f) too large>
1575 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
1579 C<Lexing code internal error (%s)>
1583 C<localtime(%.0f) too large>
1587 C<Overloaded dereference did not return a reference>
1591 C<Overloaded qr did not return a REGEXP>
1595 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
1599 New warning category C<illegalproto>
1603 Illegal character in prototype for %s : %s
1604 Prototype after '%c' for %s : %s
1606 have been moved from the C<syntax> top-level warnings category into a new
1607 first-level category, C<illegalproto>. These two warnings are currently the
1608 only ones emitted during parsing of an invalid/illegal prototype, so one
1611 no warnings 'illegalproto';
1613 to suppress only those, but not other syntax-related warnings. Warnings where
1614 prototypes are changed, ignored, or not met are still in the C<prototype>
1615 category as before. (Matt S. Trout)
1619 lvalue attribute ignored after the subroutine has been defined
1621 This new warning is issued when one attempts to mark a subroutine as
1622 lvalue after it has been defined.
1626 warn if C<++> or C<--> are unable to change the value because it's
1627 beyond the limit of representation
1629 This uses a new warnings category: "imprecision".
1633 C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
1637 Show constant in "Useless use of a constant in void context"
1641 Make the new warning report undef constants as undef
1645 Add a new warning, "Prototype after '%s'"
1649 Tweak the "Illegal character in prototype" warning so it's more precise
1650 when reporting illegal characters after _
1654 Correct the unintended interpolation of C<$\> in regex
1658 Make overflow warnings in C<gmtime> and C<localtime> only occur when
1659 warnings are enabled
1663 Improve mro merging error messages.
1665 They are now very similar to those produced by Algorithm::C3.
1669 Amelioration of the error message "Unrecognized character %s in column %d"
1671 Changes the error message to "Unrecognized character %s; marked by E<lt>--
1672 HERE after %sE<lt>-- HERE near column %d". This should make it a little
1673 simpler to spot and correct the suspicious character.
1677 Explicitely point to C<$.> when it causes an uninitialized warning for
1678 ranges in scalar context
1682 C<split> now warns when called in void context
1686 C<printf>-style functions called with too few arguments will now issue the
1687 warning C<"Missing argument in %s"> [perl #71000]
1691 C<panic: sv_chop %s>
1693 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
1694 passed a position that is not within the scalar's string buffer. This
1695 could be caused by buggy XS code, and at this point recovery is not
1700 C<Deep recursion on subroutine "%s">
1702 It is now possible to change the depth threshold for this warning from the
1703 default of 100, by recompiling the F<perl> binary, setting the C
1704 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
1708 Perl now properly returns a syntax error instead of segfaulting
1709 if C<each>, C<keys>, or C<values> is used without an argument.
1713 C<tell()> now fails properly if called without an argument and when no
1714 previous file was read.
1716 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
1717 the 5.8.x behaviour.
1721 C<overload> no longer implicitly unsets fallback on repeated 'use
1726 POSIX::strftime() can now handle Unicode characters in the format string.
1730 The Windows select() implementation now supports all empty C<fd_set>s
1735 The "syntax" category was removed from 5 warnings that should only be in
1740 Three fatal C<pack>/C<unpack> error messages have been normalized to
1745 "Unicode character is illegal" has been rephrased to be more accurate
1747 It now reads C<Unicode non-character is illegal in interchange> and the
1748 perldiag documentation has been expanded a bit.
1752 Perl now defaults to issuing a warning if a deprecated language feature
1755 To disable this feature in a given lexical scope, you should use C<no
1756 warnings 'deprecated';> For information about which language features
1757 are deprecated and explanations of various deprecation warnings, please
1762 The following diagnostics have been removed:
1772 C<Can't locate package %s for the parents of %s>
1774 This warning has been removed. In general, it only got produced in
1775 conjunction with other warnings, and removing it allowed an ISA lookup
1776 optimisation to be added.
1780 C<v-string in use/require is non-portable>
1784 =head1 Utility Changes
1792 Now looks in C<include-fixed> too, which is a recent addition to gcc's
1799 No longer incorrectly treats enum values like macros (Daniel Burr).
1801 Now handles C++ style constants (C<//>) properly in enums. (A patch from
1802 Rainer Weikusat was used; Daniel Burr also proposed a similar fix).
1808 C<LVALUE> subroutines now work under the debugger.
1810 The debugger now correctly handles proxy constant subroutines, and
1817 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out upstream bug
1820 Where the user names a module that their bug report is about, and we know the
1821 URL for its upstream bug tracker, provide a message to the user explaining
1822 that the core copies the CPAN version directly, and provide the URL for
1823 reporting the bug directly to upstream.
1829 Perl 5.11.0 added a new utility F<perlthanks>, which is a variant of
1830 F<perlbug>, but for sending non-bug-reports to the authors and maintainers
1831 of Perl. Getting nothing but bug reports can become a bit demoralising:
1832 we'll see if this changes things.
1838 No longer reports "Message sent" when it hasn't actually sent the message
1844 Fixed bugs with the match() operator in list context, remove mention of
1849 =head1 Selected Bug Fixes
1855 Ensure that pp_qr returns a new regexp SV each time. Resolves RT #69852.
1857 Instead of returning a(nother) reference to the (pre-compiled) regexp in the
1858 optree, use reg_temp_copy() to create a copy of it, and return a reference to
1859 that. This resolves issues about Regexp::DESTROY not being called in a timely
1860 fashion (the original bug tracked by RT #69852), as well as bugs related to
1861 blessing regexps, and of assigning to regexps, as described in correspondence
1862 added to the ticket.
1864 It transpires that we also need to undo the SvPVX() sharing when ithreads
1865 cloning a Regexp SV, because mother_re is set to NULL, instead of a cloned
1866 copy of the mother_re. This change might fix bugs with regexps and threads in
1867 certain other situations, but as yet neither tests nor bug reports have
1868 indicated any problems, so it might not actually be an edge case that it's
1873 Several compilation errors and segfaults when perl was built with C<-Dmad> were fixed.
1877 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
1881 C<-t> should only return TRUE for file handles connected to a TTY
1883 The Microsoft C version of C<isatty()> returns TRUE for all
1884 character mode devices, including the F</dev/null>-style "nul"
1885 device and printers like "lpt1".
1889 Fixed a regression caused by commit fafafbaf which caused a panic during
1890 parameter passing [perl #70171]
1894 On systems which in-place edits without backup files, -i'*' now works as
1895 the documentation says it does [perl #70802]
1899 Saving and restoring magic flags no longer loses readonly flag.
1903 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
1904 causes abrupt and total failure.
1908 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
1913 Using named subroutines with C<sort> should no longer lead to bus errors [perl
1918 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
1922 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
1926 C<$@> may now be assigned a read-only value (without error or busting
1931 C<sort> called recursively from within an active comparison subroutine no
1932 longer causes a bus error if run multiple times. [perl #71076]
1936 Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)
1940 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
1945 C<-I> on shebang line now adds directories in front of @INC
1946 as documented, and as does C<-I> when specified on the command-line.
1950 C<kill> is now fatal when called on non-numeric process identifiers.
1951 Previously, an C<undef> process identifier would be interpreted as a
1952 request to kill process 0, which would terminate the current process
1953 group on POSIX systems. Since process identifiers are always integers,
1954 killing a non-numeric process is now fatal.
1958 5.10.0 inadvertently disabled an optimisation, which caused a measurable
1959 performance drop in list assignment, such as is often used to assign
1960 function parameters from C<@_>. The optimisation has been re-instated, and
1961 the performance regression fixed. (This fix is also present in 5.10.1)
1965 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
1969 Some potential coredumps in PerlIO fixed [RT #57322,54828].
1973 The debugger now works with lvalue subroutines.
1977 The debugger's C<m> command was broken on modules that defined constants
1982 C<crypt> and string complement could return tainted values for untainted
1983 arguments [RT #59998].
1987 The C<-i>I<.suffix> command-line switch now recreates the file using
1988 restricted permissions, before changing its mode to match the original
1989 file. This eliminates a potential race condition [RT #60904].
1993 On some Unix systems, the value in C<$?> would not have the top bit set
1994 (C<$? & 128>) even if the child core dumped.
1998 Under some circumstances, C<$^R> could incorrectly become undefined
2003 In the XS API, various hash functions, when passed a pre-computed hash where
2004 the key is UTF-8, might result in an incorrect lookup.
2008 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2013 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo> didn't
2014 exist, even if the object's C<@ISA> contained C<Foo>.
2018 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2019 C<@ISA>, have been found and fixed.
2023 Bitwise operations on references could crash the interpreter, e.g.
2024 C<$x=\$y; $x |= "foo"> [RT #54956].
2028 Patterns including alternation might be sensitive to the internal UTF-8
2029 representation, e.g.
2031 my $byte = chr(192);
2032 my $utf8 = chr(192); utf8::upgrade($utf8);
2033 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2037 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2038 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2039 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2040 greater than 255 [RT #59908].
2044 C<B::Deparse> failed to correctly deparse various constructs:
2045 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2046 C<sub foo(_)> [RT #62484].
2050 Using C<setpgrp> with no arguments could corrupt the perl stack.
2054 The block form of C<eval> is now specifically trappable by C<Safe> and
2055 C<ops>. Previously it was erroneously treated like string C<eval>.
2059 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2060 match operator (C<~~>) [RT #63854].
2064 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2065 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2067 ("ab" x 32768) =~ /^(ab)*$/
2071 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2075 Using C<next> or C<last> to exit a C<given> block no longer produces a
2076 spurious warning like the following:
2078 Exiting given via last at foo.pl line 123
2082 On Windows, C<'.\foo'> and C<'..\foo'> were treated differently than
2083 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
2087 Assigning a format to a glob could corrupt the format; e.g.:
2089 *bar=*foo{FORMAT}; # foo format now bad
2093 Attempting to coerce a typeglob to a string or number could cause an
2094 assertion failure. The correct error message is now generated,
2095 C<Can't coerce GLOB to I<$type>>.
2099 Under C<use filetest 'access'>, C<-x> was using the wrong access mode. This
2100 has been fixed [RT #49003].
2104 C<length> on a tied scalar that returned a Unicode value would not be
2105 correct the first time. This has been fixed.
2109 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2114 A race condition inside C<PerlIOStdio_close()> has been identified and
2115 fixed. This used to cause various threading issues, including SEGVs.
2119 In C<unpack>, the use of C<()> groups in scalar context was internally
2120 placing a list on the interpreter's stack, which manifested in various
2121 ways, including SEGVs. This is now fixed [RT #50256].
2125 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2126 These have all been fixed.
2130 A 5.10.0 optimisation to clear the temporary stack within the implicit
2131 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2132 obscure bugs in seemingly unrelated parts of the interpreter [commit
2137 The line numbers for warnings inside C<elsif> are now correct.
2141 The C<..> operator now works correctly with ranges whose ends are at or
2142 close to the values of the smallest and largest integers.
2146 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2147 This has been fixed [RT #54828].
2151 An off-by-one error meant that C<index $str, ...> was effectively being
2152 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2156 Various leaks associated with named captures in regexes have been fixed
2161 A weak reference to a hash would leak. This was affecting C<DBI>
2166 Using (?|) in a regex could cause a segfault [RT #59734].
2170 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2174 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2175 unaligned 64-bit access on the SPARC architecture [RT #60574].
2179 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2180 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2185 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2190 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2191 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2196 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2197 missed (method cache issue) [RT #60220,60232].
2201 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2202 cause a memory leak [RT #63110].
2206 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2207 specified on the command line. C<-C> on the shebang line used to be a
2208 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2209 disallowed it, which broke some scripts. Now perl checks whether it is
2210 also on the command line and only dies if it is not [RT #67880].
2214 In 5.10.0, certain types of re-entrant regular expression could crash,
2215 or cause the following assertion failure [RT #60508]:
2217 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2221 Previously missing files from Unicode 5.1 Character Database are now included.
2225 C<TMPDIR> is now honored when opening an anonymous temporary file
2229 =head1 Platform Specific Changes
2231 =head2 New Platforms
2237 Patches from the Haiku maintainers have been merged in. Perl should now
2242 Perl should now build on MirOS BSD.
2247 =head2 Discontinued Platforms
2253 Support for Apollo DomainOS was removed in Perl 5.11.0
2257 Support for Tenon Intersystems MachTen Unix layer for MacOS Classic was
2258 removed in Perl 5.11.0
2262 Support for Atari MiNT was removed in Perl 5.11.0.
2266 =head2 Updated Platforms
2270 =item Darwin (Mac OS X)
2276 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2277 as it's still buggy.
2281 Correct infelicities in the regexp used to identify buggy locales
2282 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2292 Fix thread library selection [perl #69686]
2302 Initial support for mingw64 is now available
2306 Various bits of Perl's build infrastructure are no longer converted to
2307 win32 line endings at release time. If this hurts you, please report the
2308 problem with the L<perlbug> program included with perl.
2312 Always add a manifest resource to C<perl.exe> to specify the C<trustInfo>
2313 settings for Windows Vista and later. Without this setting Windows
2314 will treat C<perl.exe> as a legacy application and apply various
2315 heuristics like redirecting access to protected file system areas
2316 (like the "Program Files" folder) to the users "VirtualStore"
2317 instead of generating a proper "permission denied" error.
2319 For VC8 and VC9 this manifest setting is automatically generated by
2320 the compiler/linker (together with the binding information for their
2321 respective runtime libraries); for all other compilers we need to
2322 embed the manifest resource explicitly in the external resource file.
2324 This change also requests the Microsoft Common-Controls version 6.0
2325 (themed controls introduced in Windows XP) via the dependency list
2326 in the assembly manifest. For VC8 and VC9 this is specified using the
2327 C</manifestdependency> linker commandline option instead.
2331 Improved message window handling means that C<alarm> and C<kill> messages
2332 will no longer be dropped under race conditions.
2342 Enable IPv6 support on cygwin 1.7 and newer
2352 Make -UDEBUGGING the default on VMS for 5.12.0.
2354 Like it has been everywhere else for ages and ages. Also make
2355 command-line selection of -UDEBUGGING and -DDEBUGGING work in
2356 configure.com; before the only way to turn it off was by saying
2357 no in answer to the interactive question.
2361 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2366 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2367 if C<$/> was set to a numeric reference (to indicate record-style reads).
2372 VMS now supports C<getgrgid>.
2376 Many improvements and cleanups have been made to the VMS file name handling
2377 and conversion code.
2381 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2382 status in a VMS condition value for better interaction with GNV's bash
2383 shell and other utilities that depend on POSIX exit values. See
2384 L<perlvms/"$?"> for details.
2388 C<File::Copy> now detects Unix compatibility mode on VMS.
2394 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from F<libbsd>.
2396 Removed F<libgdbm> for AIX 5L and 6.1. The F<libgdbm> is delivered as an
2397 optional package with the AIX Toolbox. Unfortunately the 64 bit version
2400 Hints changes mean that AIX 4.2 should work again.
2404 On Cygwin we now strip the last number from the DLL. This has been the
2405 behaviour in the cygwin.com build for years. The hints files have been
2411 The hints files now identify the correct threading libraries on FreeBSD 7
2416 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2417 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2421 Hints now supports versions 5.*.
2425 Various changes from Stratus have been merged in.
2429 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2433 =head1 Known Problems
2435 This is a list of some significant unfixed bugs, which are regressions
2436 from either 5.10.0 or 5.8.x.
2442 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
2443 (typically introduced by C<my $_> or implicitly by C<given>). The variable
2444 which gets set for each iteration is the package variable C<$_>, not the
2445 lexical C<$_> [RT #67694].
2447 A similar issue may occur in other modules that provide functions which
2448 take a block as their first argument, like
2450 foo { ... $_ ...} list
2454 The C<charnames> pragma may generate a run-time error when a regex is
2455 interpolated [RT #56444]:
2457 use charnames ':full';
2458 my $r1 = qr/\N{THAI CHARACTER SARA I}/;
2459 "foo" =~ $r1; # okay
2460 "foo" =~ /$r1+/; # runtime error
2462 A workaround is to generate the character outside of the regex:
2464 my $a = "\N{THAI CHARACTER SARA I}";
2467 However, C<$r1> must be used within the scope of the C<use charnames> for this
2472 Some regexes may run much more slowly when run in a child thread compared
2473 with the thread the pattern was compiled into [RT #55600].
2477 Untriaged test crashes on Windows 2000
2479 Several porters have reported mysterious crashes when Perl's entire test suite is run after a build on certain Windows 2000 systems. When run by hand, the individual tests reportedly work fine.
2483 Known test failures on VMS
2485 Perl 5.11.1 fails a small set of core and CPAN tests as of this release.
2486 With luck, that'll be sorted out for 5.11.2
2490 Known test failures on VMS
2492 Perl 5.11.2 fails a small set of core and CPAN tests as of this
2493 release. With luck, that'll be sorted out for 5.11.3.
2497 =head1 Acknowledgements
2499 Perl 5.12.0 represents approximately two years of development since
2500 Perl 5.10.0 and contains __ lines of changes across ___ files
2501 from __ authors and committers:
2505 Many of the changes included in this version originated in the CPAN
2506 modules included in Perl's core. We're grateful to the entire CPAN
2507 community for helping Perl to flourish.
2509 =head1 Reporting Bugs
2511 If you find what you think is a bug, you might check the articles
2512 recently posted to the comp.lang.perl.misc newsgroup and the perl
2513 bug database at L<http://rt.perl.org/perlbug/>. There may also be
2514 information at L<http://www.perl.org/>, the Perl Home Page.
2516 If you believe you have an unreported bug, please run the B<perlbug>
2517 program included with your release. Be sure to trim your bug down
2518 to a tiny but sufficient test case. Your bug report, along with the
2519 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2520 analyzed by the Perl porting team.
2522 If the bug you are reporting has security implications, which make it
2523 inappropriate to send to a publicly archived mailing list, then please send
2524 it to perl5-security-report@perl.org. This points to a closed subscription
2525 unarchived mailing list, which includes all the core committers, who be able
2526 to help assess the impact of issues, figure out a resolution, and help
2527 co-ordinate the release of patches to mitigate or fix the problem across all
2528 platforms on which Perl is supported. Please only use this address for
2529 security issues in the Perl core, not for modules independently
2530 distributed on CPAN.
2534 The F<Changes> file for an explanation of how to view exhaustive details
2537 The F<INSTALL> file for how to build Perl.
2539 The F<README> file for general stuff.
2541 The F<Artistic> and F<Copying> files for copyright information.