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 right 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 Perl can now handle every Unicode character property. A new pod,
84 L<perluniprops>, lists all available non-Unihan character properties. By
85 default the Unihan properties and certain others (deprecated and Unicode
86 internal-only ones) are not exposed. See below for more details on
87 these; there is also a section in the pod listing them, and why they are
90 Perl now fully supports the Unicode compound-style of using C<=> and C<:>
91 in writing regular expressions: C<\p{property=value}> and
92 C<\p{property:value}> (both of which mean the same thing).
94 Perl now fully supports the Unicode loose matching rules for text
95 between the braces in C<\p{...}> constructs. In addition, Perl also allows
96 underscores between digits of numbers.
98 All the Unicode-defined synonyms for properties and property values are
101 C<qr/\X/>, which matches a Unicode logical character, has been expanded to work
102 better with various Asian languages. It now is defined as an C<extended
103 grapheme cluster>. (See L<http://www.unicode.org/reports/tr29/>).
104 Anything matched previously that made sense will continue to be matched. But
111 C<\X> will now not break apart a C<S<CR LF>> sequence.
115 C<\X> will now match a sequence including the C<ZWJ> and C<ZWNJ> characters.
119 C<\X> will now always match at least one character, including an initial mark.
120 Marks generally come after a base character, but it is possible in Unicode to
121 have them in isolation, and C<\X> will now handle that case, for example at the
122 beginning of a line or after a C<ZWSP>. And this is the part where C<\X>
123 doesn't match the things that it used to that don't make sense. Formerly, for
124 example, you could have the nonsensical case of an accented LF.
128 C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai and Lao
133 Otherwise, this change should be transparent for the non-affected languages.
135 C<\p{...}> matches using the Canonical_Combining_Class property were
136 completely broken in previous Perls. This is now fixed.
138 In previous Perls, the Unicode C<Decomposition_Type=Compat> property and a
139 Perl extension had the same name, which led to neither matching all the
140 correct values (with more than 100 mistakes in one, and several thousand
141 in the other). The Perl extension has now been renamed to be
142 C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the same
143 meaning as was previously intended, namely the union of all the
144 non-canonical Decomposition types, with Unicode C<Compat> being just one of
147 C<\p{Uppercase}> and C<\p{Lowercase}> have been brought into line with the
148 Unicode definitions. This means they each match a few more characters
151 C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This means it
152 no longer will match Private Use (gc=co), Surrogates (gc=cs), nor Format
153 (gc=cf) code points. The Format code points represent the biggest
154 possible problem. All but 36 of them are either officially deprecated
155 or strongly discouraged from being used. Of those 36, likely the most
156 widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ, WJ, and
157 similar, plus Bi-directional controls.
159 C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. The Perl
160 definition included a number of things that aren't really alpha (all
161 marks), while omitting many that were. As a direct consequence, the
162 definitions of C<\p{Alnum}> and C<\p{Word}> which depend on Alpha also change.
164 C<\p{Word}> also now doesn't match certain characters it wasn't supposed
165 to, such as fractions.
167 C<\p{Print}> no longer matches the line control characters: Tab, LF, CR,
168 FF, VT, and NEL. This brings it in line with the documentation.
170 C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
172 The Numeric type property has been extended to include the Unihan
175 There is a new Perl extension, the 'Present_In', or simply 'In',
176 property. This is an extension of the Unicode Age property, but
177 C<\p{In=5.0}> matches any code point whose usage has been determined
178 I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
179 added in I<precisely> version 5.0.
181 A number of properties did not have the correct values for unassigned
182 code points. This is now fixed. The affected properties are
183 Bidi_Class, East_Asian_Width, Joining_Type, Decomposition_Type,
184 Hangul_Syllable_Type, Numeric_Type, and Line_Break.
186 The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
187 have been updated to their current Unicode definitions.
189 Certain properties that are supposed to be Unicode internal-only were
190 erroneously exposed by previous Perls. Use of these in regular
191 expressions will now generate, if enabled, a deprecated warning message.
192 The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
193 Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
194 Other_Math, and Other_Uppercase.
196 An installation can now fairly easily change which Unicode properties
197 Perl understands. As mentioned above, certain properties are by default
198 turned off. These include all the Unihan properties (which should be
199 accessible via the CPAN module Unicode::Unihan) and any deprecated or
200 Unicode internal-only property that Perl has never exposed.
202 The generated files in the C<lib/unicore/To> directory are now more
203 clearly marked as being stable, directly usable by applications.
204 New hash entries in them give the format of the normal entries,
205 which allows for easier machine parsing. Perl can generate files
206 in this directory for any property, though most are suppressed. An
207 installation can choose to change which get written. Instructions
208 are in L<perluniprops>.
210 =head2 Regular Expressions
212 U+0FFFF is now a legal character in regular expressions.
214 =head2 Unicode properties
216 C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
217 means that in addition to the characters it currently matches,
218 C<[A-Fa-f0-9]>, it will also match their fullwidth equivalent forms, for
219 example U+FF10: FULLWIDTH DIGIT ZERO.
221 =head2 Unicode Character Database 5.1.0
223 The copy of the Unicode Character Database included in Perl 5.11.0 has
224 been updated to 5.1.0 from 5.0.0. See
225 L<http://www.unicode.org/versions/Unicode5.1.0/#Notable_Changes> for the
228 =head2 A proper interface for pluggable Method Resolution Orders
230 As of Perl 5.11.0 there is a new interface for plugging and using method
231 resolution orders other than the default (linear depth first search).
232 The C3 method resolution order added in 5.10.0 has been re-implemented as
233 a plugin, without changing its Perl-space interface. See L<perlmroapi> for
236 =head2 The C<overloading> pragma
238 This pragma allows you to lexically disable or enable overloading
239 for some or all operations. (Yuval Kogman)
241 =head2 C<\N> regex escape
243 A new regex escape has been added, C<\N>. It will match any character that
244 is not a newline, independently from the presence or absence of the single
245 line match modifier C</s>. (If C<\N> is followed by an opening brace and
246 by a letter, perl will still assume that a Unicode character name is
247 coming, so compatibility is preserved.) (Rafael Garcia-Suarez)
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 Add 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 I<exactly> the same way as C<use NAME VERSION>
352 C<$VERSION> is set at compile time
356 Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
360 As it requires VERSION to be a numeric literal or v-string
361 literal, it can be statically parsed by toolchain modules
362 without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
366 Alpha versions with underscores do not need to be quoted; static
367 parsing will preserve the underscore, but during compilation, Perl
368 will remove underscores as it does for all numeric literals
370 It does not break old code with only C<package NAME>, but code that uses
371 C<package NAME VERSION> will need to be restricted to perl 5.11.X or newer
372 This is analogous to the change to C<open> from two-args to three-args.
373 Users requiring the latest Perl will benefit, and perhaps N years from
374 now it will become standard practice when Perl 5.12 is targeted the way
379 =head1 Incompatible Changes
381 =head2 Version number formats
383 Acceptable version number formats have been formalized into "strict" and
384 "lax" rules. C<package NAME VERSION> takes a strict version number. C<use
385 NAME VERSION> takes a lax version number. C<UNIVERSAL::VERSION> and the
386 L<version> object constructors take lax version numbers. Providing an
387 invalid version will result in a fatal error.
389 These formats will be documented fully in the L<version> module in a
390 subsequent release of Perl 5.11. To a first approximation, a "strict"
391 version number is a positive decimal number (integer or decimal-fraction)
392 without exponentiation or else a dotted-decimal v-string with a leading 'v'
393 character and at least three components. A "lax" version number allows
394 v-strings with fewer than three components or without a leading 'v'. Under
395 "lax" rules, both decimal and dotted-decimal versions may have a trailing
396 "alpha" component separated by an underscore character after a fractional
397 or dotted-decimal component.
399 The L<version> module adds C<version::is_strict> and C<version::is_lax>
400 functions to check a scalar against these rules.
406 The boolkeys op moved to the group of hash ops. This breaks binary compatibility.
410 C<\s> C<\w> and C<\d> once again have the semantics they had in Perl 5.8.x.
414 Filehandles are blessed directly into C<IO::Handle>, as C<FileHandle> is merely a wrapper around C<IO::Handle>.
416 The previous behaviour was to bless Filehandles into L<FileHandle>
417 (an empty proxy class) if it was loaded into memory and otherwise
418 to bless them into C<IO::Handle>.
422 =head2 Unicode interpretation of \w, \d, \s, and the POSIX character classes redefined.
424 Previous versions of Perl tried to map POSIX style character class definitions onto
425 Unicode property names so that patterns would "dwim" when matches were made against latin-1 or
426 unicode strings. This proved to be a mistake, breaking character class negation, causing
427 forward compatibility problems (as Unicode keeps updating their property definitions and adding
428 new characters), and other problems.
430 Therefore we have now defined a new set of artificial "unicode" property names which will be
431 used to do unicode matching of patterns using POSIX style character classes and perl short-form
432 escape character classes like \w and \d.
434 The key change here is that \d will no longer match every digit in the unicode standard
435 (there are thousands) nor will \w match every word character in the standard, instead they
436 will match precisely their POSIX or Perl definition.
438 Those needing to match based on Unicode properties can continue to do so by using the \p{} syntax
439 to match whichever property they like, including the new artificial definitions.
441 B<NOTE:> This is a backwards incompatible no-warning change in behaviour. If you are upgrading
442 and you process large volumes of text look for POSIX and Perl style character classes and
443 change them to the relevent property name (by removing the word 'Posix' from the current name).
445 The following table maps the POSIX character class names, the escapes and the old and new
446 Unicode property mappings:
448 POSIX Esc Class New-Property ! Old-Property
449 ----------------------------------------------+-------------
450 alnum [0-9A-Za-z] IsPosixAlnum ! IsAlnum
451 alpha [A-Za-z] IsPosixAlpha ! IsAlpha
452 ascii [\000-\177] IsASCII = IsASCII
453 blank [\011 ] IsPosixBlank !
454 cntrl [\0-\37\177] IsPosixCntrl ! IsCntrl
455 digit \d [0-9] IsPosixDigit ! IsDigit
456 graph [!-~] IsPosixGraph ! IsGraph
457 lower [a-z] IsPosixLower ! IsLower
458 print [ -~] IsPosixPrint ! IsPrint
459 punct [!-/:-@[-`{-~] IsPosixPunct ! IsPunct
460 space [\11-\15 ] IsPosixSpace ! IsSpace
461 \s [\11\12\14\15 ] IsPerlSpace ! IsSpacePerl
462 upper [A-Z] IsPosixUpper ! IsUpper
463 word \w [0-9A-Z_a-z] IsPerlWord ! IsWord
464 xdigit [0-9A-Fa-f] IsXDigit = IsXDigit
466 If you wish to build perl with the old mapping you may do so by setting
468 #define PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS 1
470 in regcomp.h, and then setting
472 PERL_TEST_LEGACY_POSIX_CC
474 to true your enviornment when testing.
479 In @INC, ARCHLIB and PRIVLIB now occur after after the current version's
480 site_perl and vendor_perl.
482 =head2 Switch statement changes
484 The handling of complex expressions by the C<given>/C<when> switch
485 statement has been enhanced. These enhancements are also available in
486 5.10.1 and subsequent 5.10 releases. There are two new cases where C<when> now
487 interprets its argument as a boolean, instead of an expression to be used
490 =head2 flip-flop operators
492 The C<..> and C<...> flip-flop operators are now evaluated in boolean
493 context, following their usual semantics; see L<perlop/"Range Operators">.
495 Note that, as in perl 5.10.0, C<when (1..10)> will not work to test
496 whether a given value is an integer between 1 and 10; you should use
497 C<when ([1..10])> instead (note the array reference).
499 However, contrary to 5.10.0, evaluating the flip-flop operators in boolean
500 context ensures it can now be useful in a C<when()>, notably for
501 implementing bistable conditions, like in:
503 when (/^=begin/ .. /^=end/) {
507 =head2 defined-or operator
509 A compound expression involving the defined-or operator, as in
510 C<when (expr1 // expr2)>, will be treated as boolean if the first
511 expression is boolean. (This just extends the existing rule that applies
512 to the regular or operator, as in C<when (expr1 || expr2)>.)
514 =head2 Smart match changes
516 This section details more changes brought to the semantics to
517 the smart match operator, that naturally also modify the behaviour
518 of the switch statements where smart matching is implicitly used.
519 These changers were also made for the 5.10.1 release, and will remain in
520 subsequent 5.10 releases.
523 =head3 Changes to type-based dispatch
525 The smart match operator C<~~> is no longer commutative. The behaviour of
526 a smart match now depends primarily on the type of its right hand
527 argument. Moreover, its semantics have been adjusted for greater
528 consistency or usefulness in several cases. While the general backwards
529 compatibility is maintained, several changes must be noted:
535 Code references with an empty prototype are no longer treated specially.
536 They are passed an argument like the other code references (even if they
537 choose to ignore it).
541 C<%hash ~~ sub {}> and C<@array ~~ sub {}> now test that the subroutine
542 returns a true value for each key of the hash (or element of the
543 array), instead of passing the whole hash or array as a reference to
548 Due to the commutativity breakage, code references are no longer
549 treated specially when appearing on the left of the C<~~> operator,
550 but like any vulgar scalar.
554 C<undef ~~ %hash> is always false (since C<undef> can't be a key in a
555 hash). No implicit conversion to C<""> is done (as was the case in perl
560 C<$scalar ~~ @array> now always distributes the smart match across the
561 elements of the array. It's true if one element in @array verifies
562 C<$scalar ~~ $element>. This is a generalization of the old behaviour
563 that tested whether the array contained the scalar.
567 The full dispatch table for the smart match operator is given in
568 L<perlsyn/"Smart matching in detail">.
570 =head3 Smart match and overloading
572 According to the rule of dispatch based on the rightmost argument type,
573 when an object overloading C<~~> appears on the right side of the
574 operator, the overload routine will always be called (with a 3rd argument
575 set to a true value, see L<overload>.) However, when the object will
576 appear on the left, the overload routine will be called only when the
577 rightmost argument is a simple scalar. This way distributivity of smart match
578 across arrays is not broken, as well as the other behaviours with complex
579 types (coderefs, hashes, regexes). Thus, writers of overloading routines
580 for smart match mostly need to worry only with comparing against a scalar,
581 and possibly with stringification overloading; the other common cases
582 will be automatically handled consistently.
584 C<~~> will now refuse to work on objects that do not overload it (in order
585 to avoid relying on the object's underlying structure). (However, if the
586 object overloads the stringification or the numification operators, and
587 if overload fallback is active, it will be used instead, as usual.)
589 =head2 Labels can't be keywords
591 Labels used as targets for the C<goto>, C<last>, C<next> or C<redo>
592 statements cannot be keywords anymore. This restriction will prevent
593 potential confusion between the C<goto LABEL> and C<goto EXPR> syntaxes:
594 for example, a statement like C<goto print> would jump to a label whose
595 name would be the return value of C<print()>, (usually 1), instead of a
596 label named C<print>. Moreover, the other control flow statements
597 would just ignore any keyword passed to them as a label name. Since
598 such labels cannot be defined anymore, this kind of error will be
601 =head2 Other incompatible changes
607 The semantics of C<use feature :5.10*> have changed slightly.
608 See L<"Modules and Pragmata"> for more information.
612 It is now a run-time error to use the smart match operator C<~~>
613 with an object that has no overload defined for it. (This way
614 C<~~> will not break encapsulation by matching against the
615 object's internal representation as a reference.)
619 The version control system used for the development of the perl
620 interpreter has been switched from Perforce to git. This is mainly an
621 internal issue that only affects people actively working on the perl core;
622 but it may have minor external visibility, for example in some of details
623 of the output of C<perl -V>. See L<perlrepository> for more information.
627 The internal structure of the C<ext/> directory in the perl source has
628 been reorganised. In general, a module C<Foo::Bar> whose source was
629 stored under F<ext/Foo/Bar/> is now located under F<ext/Foo-Bar/>. Also,
630 nearly all dual-life modules have been moved from F<lib/> to F<ext/>. This
631 is purely a source tarball change, and should make no difference to the
632 compilation or installation of perl, unless you have a very customised build
633 process that explicitly relies on this structure, or which hard-codes the
634 C<nonxs_ext> F<Configure> parameter. Specifically, this change does not by
635 default alter the location of any files in the final installation.
639 As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
640 C<Test::Harness::Straps> module has been removed.
641 See L</"Updated Modules"> for more details.
645 As part of the C<ExtUtils::MakeMaker> upgrade, the
646 C<ExtUtils::MakeMaker::bytes> and C<ExtUtils::MakeMaker::vmsish> modules
647 have been removed from this distribution.
651 C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
655 This one is actually a change introduced in 5.10.0, but it was missed
656 from that release's perldelta, so it is mentioned here instead.
658 A bugfix related to the handling of the C</m> modifier and C<qr> resulted
659 in a change of behaviour between 5.8.x and 5.10.0:
661 # matches in 5.8.x, doesn't match in 5.10.0
662 $re = qr/^bar/; "foo\nbar" =~ /$re/m;
666 C<length undef> now returns undef.
670 Unsupported private C API functions are now declared "static" to prevent
671 leakage to Perl's public API.
675 To support the bootstrapping process, F<miniperl> no longer builds with
676 UTF-8 support in the regexp engine.
678 This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
679 Without this there's a bootstrapping problem, as miniperl can't load the UTF-8
680 components of the regexp engine, because they're not yet built.
684 F<miniperl>'s @INC is now restricted to just -I..., the split of $ENV{PERL5LIB}, and "."
688 A space or a newline is now required after a C<"#line XXX"> directive.
692 Tied filehandles now have an additional method EOF which provides the EOF type
696 To better match all other flow control statements, C<foreach> may no longer be used as an attribute.
702 From time to time, Perl's developers find it necessary to deprecate
703 features or modules we've previously shipped as part of the core
704 distribution. We are well aware of the pain and frustration that a
705 backwards-incompatible change to Perl can cause for developers building
706 or maintaining software in Perl. You can be sure that when we deprecate
707 a functionality or syntax, it isn't a choice we make lightly. Sometimes,
708 we choose to deprecate functionality or syntax because it was found to
709 be poorly designed or implemented. Sometimes, this is because they're
710 holding back other features or causing performance problems. Sometimes,
711 the reasons are more complex. Wherever possible, we try to keep deprecated
712 functionality available to developers in its previous form for at least
713 one major release. So long as a deprecated feature isn't actively
714 disrupting our ability to maintain and extend Perl, we'll try to leave
715 it in place as long as possible.
717 The following items are now deprecated.
721 =item Use of C<:=> to mean an empty attribute list is now deprecated.
723 An accident of Perl's parser meant that these constructions were all
730 with the C<:> being treated as the start of an attribute list, which
731 ends before the C<=>. As whitespace is not significant here, all are
732 parsed as an empty attribute list, hence all the above are equivalent
733 to, and better written as
737 because no attribute processing is done for an empty list.
739 As is, this meant that C<:=> cannot be used as a new token, without
740 silently changing the meaning of existing code. Hence that particular
741 form is now deprecated, and will become a syntax error. If it is
742 absolutely necessary to have empty attribute lists (for example,
743 because of a code generator) then avoid the warning by adding a space
746 =item C<< UNIVERSAL-E<gt>import() >>
748 The method C<< UNIVERSAL-E<gt>import() >> is now deprecated. Attempting to
749 pass import arguments to a C<use UNIVERSAL> statement will result in a
750 deprecation warning. (This is a less noisy version of the full deprecation
751 warning added in 5.11.0.)
753 =item Use of "goto" to jump into a construct is deprecated
755 Using C<goto> to jump from an outer scope into an inner
756 scope is now deprecated. This rare use case was causing
757 problems in the implementation of scopes.
759 =item C<Switch> is buggy and should be avoided.
761 From perl 5.11.0 onwards, it is
762 intended that any use of the core version of this module will emit a
763 warning, and that the module will eventually be removed from the core
764 (probably in perl 5.14.0). See L<perlsyn/"Switch statements"> for its
767 =item Deprecated Modules
769 The following modules will be removed from the core distribution in a future
770 release, and should be installed from CPAN instead. Distributions on CPAN
771 which require these should add them to their prerequisites. The core versions
772 of these modules warnings will issue a deprecation warning.
778 =item C<Pod::Plainer>
786 C<suidperl> has been removed. It used to provide a mechanism to
787 emulate setuid permission bits on systems that don't support it properly.
789 =item Assignment to $[
793 Remove attrs, which has been deprecated since 1999-10-02.
795 =item Use of the attribute :locked on subroutines.
797 =item Use of "locked" with the attributes pragma.
799 =item Use of "unique" with the attributes pragma.
801 =item Numerous Perl 4-era libraries:
803 F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
804 F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
805 F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
806 F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
807 F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
808 F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
809 F<timelocal.pl> are all now deprecated. Using them will incur a warning.
813 =head1 Modules and Pragmata
815 =head2 Dual-lifed modules moved
817 Dual-lifed modules maintained primarily in the Perl core now live in dist/.
818 Dual-lifed modules maintained primarily on CPAN now live in cpan/
820 In previous releases of Perl, it was customary to enumerate all module
821 changes in this section of the C<perldelta> file. From 5.11.0 forward
822 only notable updates (such as new or deprecated modules ) will be
823 listed in this section. For a complete reference to the versions of
824 modules shipped in a given release of perl, please see L<Module::CoreList>.
826 =head2 New Modules and Pragmata
834 This is a new lexically-scoped alternative for the C<Fatal> module.
835 The bundled version is 2.06_01. Note that in this release, using a string
836 eval when C<autodie> is in effect can cause the autodie behaviour to leak
837 into the surrounding scope. See L<autodie/"BUGS"> for more details.
841 C<Compress::Raw::Bzip2>
843 This has been added to the core (version 2.020).
849 This pragma establishes an ISA relationship with base classes at compile
850 time. It provides the key feature of C<base> without the feature creep.
856 This has been added to the core (version 1.39).
860 =head2 Pragmata Changes
868 See L</"The C<overloading> pragma"> above.
874 The C<attrs> pragma has been removed. It had been marked as deprecated since
881 The Unicode F<NameAliases.txt> database file has been added. This has the
882 effect of adding some extra C<\N> character names that formerly wouldn't
883 have been recognised; for example, C<"\N{LATIN CAPITAL LETTER GHA}">.
889 The meaning of the C<:5.10> and C<:5.10.X> feature bundles has
890 changed slightly. The last component, if any (i.e. C<X>) is simply ignored.
891 This is predicated on the assumption that new features will not, in
892 general, be added to maintenance releases. So C<:5.10> and C<:5.10.X>
893 have identical effect. This is a change to the behaviour documented for
900 Upgraded from version 1.00 to 1.01. Performance for single inheritance is 40%
901 faster - see L</"Performance Enhancements"> below.
903 C<mro> is now implemented as an XS extension. The documented interface has not
904 changed. Code relying on the implementation detail that some C<mro::>
905 methods happened to be available at all times gets to "keep both pieces".
911 Supports %.0f formatting internally.
917 Allow overloading of 'qr'.
923 Upgraded from version 1.19 to 1.20.
929 This pragma no longer suppresses C<Use of uninitialized value in range (or flip)> warnings. [perl #71204]
935 Upgraded from 1.13 to 1.14. Added the C<unicode_strings> feature:
937 use feature "unicode_strings";
939 This pragma turns on Unicode semantics for the case-changing operations
940 (uc/lc/ucfirst/lcfirst) on strings that don't have the internal UTF-8 flag set,
941 but that contain single-byte characters between 128 and 255.
947 Upgraded from version 1.74 to 1.75.
953 Upgraded from version 0.03 to 0.03.
955 This version introduces the C<stash_name> method to allow subclasses of less to
956 pick where in %^H to store their stash.
962 Upgraded from version 0.77 to 0.81.
964 This version adds support for L</Version number formats> as described earlier
965 in this document and in its own documentation.
971 Upgraded from 1.07 to 1.09.
973 Added new C<warnings::fatal_enabled()> function.
974 This version adds the C<illegalproto> warning category. See also L</New or
975 Changed Diagnostics> for this change.
980 =head2 Updated Modules
984 =item XXX TODO RECALCULATE THIS VS 5.10.0
988 =head2 Removed Modules and Pragmata
996 Removed from the Perl core. Prior version was 'undef'.
1000 =head1 Documentation
1002 =head2 New Documentation
1010 This contains instructions on how to build perl for the Haiku platform.
1016 This describes the new interface for pluggable Method Resolution Orders.
1022 This document, by Richard Foley, provides an introduction to the use of
1023 performance and optimization techniques which can be used with particular
1024 reference to perl programs.
1030 This describes how to access the perl source using the I<git> version
1035 L<perlpolicy> extends the "Social contract about contributed modules" into
1036 the beginnings of a document on Perl porting policies.
1040 =head2 Changes to Existing Documentation
1042 The various large F<Changes*> files (which listed every change made to perl
1043 over the last 18 years) have been removed, and replaced by a small file,
1044 also called F<Changes>, which just explains how that same information may
1045 be extracted from the git version control system.
1047 The file F<Porting/patching.pod> has been deleted, as it mainly described
1048 interacting with the old Perforce-based repository, which is now obsolete.
1049 Information still relevant has been moved to L<perlrepository>.
1051 L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
1052 generated at build time, rather than being shipped as part of the release.
1058 Documented -X overloading.
1062 Documented that C<when()> treats specially most of the filetest operators
1066 Documented when as a syntax modifier
1070 Eliminated "Old Perl threads tutorial", which describes 5005 threads.
1072 F<pod/perlthrtut.pod> is the same material reworked for ithreads.
1076 Correct previous documentation: v-strings are not deprecated
1078 With version objects, we need them to use MODULE VERSION syntax. This
1079 patch removes the deprecation note.
1083 Added security contact information to L<perlsec>
1085 A significant fraction of the core documentation has been updated to clarify
1086 the behavior of Perl's Unicode handling.
1088 Much of the remaining core documentation has been reviewed and edited
1089 for clarity, consistent use of language, and to fix the spelling of Tom
1090 Christiansen's name.
1092 The Pod specification (L<perlpodspec>) has been updated to bring the
1093 specification in line with modern usage already supported by most Pod systems.
1094 A parameter string may now follow the format name in a "begin/end" region.
1095 Links to URIs with a text description are now allowed. The usage of
1096 C<LE<lt>"section"E<gt>> has been marked as deprecated.
1098 L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
1099 conditional loading of modules despite the implicit BEGIN block around C<use>.
1103 Documentation for C<$1> in perlvar.pod clarified
1107 =head1 Performance Enhancements
1113 A new internal cache means that C<isa()> will often be faster.
1117 The implementation of C<C3> Method Resolution Order has been optimised -
1118 linearisation for classes with single inheritance is 40% faster. Performance
1119 for multiple inheritance is unchanged.
1123 Under C<use locale>, the locale-relevant information is now cached on
1124 read-only values, such as the list returned by C<keys %hash>. This makes
1125 operations such as C<sort keys %hash> in the scope of C<use locale> much
1130 Empty C<DESTROY> methods are no longer called.
1134 Faster C<Perl_sv_utf8_upgrade()>
1138 Speed up C<keys> on empty hash
1142 C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>
1146 Reversing an array to itself (as in C<@a = reverse @a>) in void context
1147 now happens in-place and is several orders of magnitude faster than it
1148 used to be. It will also preserve non-existent elements whenever
1149 possible, i.e. for non magical arrays or tied arrays with C<EXISTS> and
1154 =head1 Installation and Configuration Improvements
1156 =head2 F<ext/> reorganisation
1158 The layout of directories in F<ext> has been revised. Specifically, all
1159 extensions are now flat, and at the top level, with C</> in pathnames
1160 replaced by C<->, so that F<ext/Data/Dumper/> is now F<ext/Data-Dumper/>,
1161 etc. The names of the extensions as specified to F<Configure>, and as
1162 reported by C<%Config::Config> under the keys C<dynamic_ext>,
1163 C<known_extensions>, C<nonxs_ext> and C<static_ext> have not changed, and
1164 still use C</>. Hence this change will not have any affect once perl is
1165 installed. C<Safe> has been split out from being part of C<Opcode>, and
1166 C<mro> is now an extension in its own right.
1168 Nearly all dual-life modules have been moved from F<lib> to F<ext>, and will
1169 now appear as known C<nonxs_ext>. This will made no difference to the
1170 structure of an installed perl, nor will the modules installed differ,
1171 unless you run F<Configure> with options to specify an exact list of
1172 extensions to build. In this case, you will rapidly become aware that you
1173 need to add to your list, because various modules needed to complete the
1174 build, such as C<ExtUtils::ParseXS>, have now become extensions, and
1175 without them the build will fail well before it attempts to run the
1178 =head2 Configuration improvements
1180 If C<vendorlib> and C<vendorarch> are the same, then they are only added to
1183 C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
1184 perl is built with C<-Dusedevel>.
1186 F<Configure> will enable use of C<-fstack-protector>, to provide protection
1187 against stack-smashing attacks, if the compiler supports it.
1189 F<Configure> will now determine the correct prototypes for re-entrant
1190 functions, and for C<gconvert>, if you are using a C++ compiler rather
1193 On Unix, if you build from a tree containing a git repository, the
1194 configuration process will note the commit hash you have checked out, for
1195 display in the output of C<perl -v> and C<perl -V>. Unpushed local commits
1196 are automatically added to the list of local patches displayed by
1199 USE_ATTRIBUTES_FOR_PERLIO is now reported in the compile-time options
1200 listed by the C<-V> switch.
1202 =head2 Compilation improvements
1204 As part of the flattening of F<ext>, all extensions on all platforms are
1205 built by F<make_ext.pl>. This replaces the Unix-specific
1206 F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
1207 F<win32/buildext.pl>.
1210 =head1 Changed Internals
1216 C<Perl_pmflag> has been removed from the public API. Calling it now
1217 generates a deprecation warning, and it will be removed in a future
1218 release. Although listed as part of the API, it was never documented,
1219 and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
1220 core, it has been replaced by a static function.
1224 Perl_magic_setmglob now knows about globs, fixing RT #71254.
1228 TODO: C<SVt_RV> is gone. RVs are now stored in IVs
1232 TODO: REGEXPs are first class
1236 TODO: OOK is reworked, such that an OOKed scalar is PV not PVIV
1240 The J.R.R. Tolkien quotes at the head of C source file have been checked and
1241 proper citations added, thanks to a patch from Tom Christiansen.
1245 C<Perl_vcroak()> now accepts a null first argument. In addition, a full audit
1246 was made of the "not NULL" compiler annotations, and those for several
1247 other internal functions were corrected.
1251 New macros C<dSAVEDERRNO>, C<dSAVE_ERRNO>, C<SAVE_ERRNO>, C<RESTORE_ERRNO>
1252 have been added to formalise the temporary saving of the C<errno>
1257 The function C<Perl_sv_insert_flags> has been added to augment
1262 The function C<Perl_newSV_type(type)> has been added, equivalent to
1263 C<Perl_newSV()> followed by C<Perl_sv_upgrade(type)>.
1267 The function C<Perl_newSVpvn_flags()> has been added, equivalent to
1268 C<Perl_newSVpvn()> and then performing the action relevant to the flag.
1270 Two flag bits are currently supported.
1278 This will call C<SvUTF8_on()> for you. (Note that this does not convert an
1279 sequence of ISO 8859-1 characters to UTF-8). A wrapper, C<newSVpvn_utf8()>
1280 is available for this.
1286 Call C<Perl_sv_2mortal()> on the new SV.
1290 There is also a wrapper that takes constant strings, C<newSVpvs_flags()>.
1294 The function C<Perl_croak_xs_usage> has been added as a wrapper to
1299 The functions C<PerlIO_find_layer> and C<PerlIO_list_alloc> are now
1304 C<PL_na> has been exterminated from the core code, replaced by local STRLEN
1305 temporaries, or C<*_nolen()> calls. Either approach is faster than C<PL_na>,
1306 which is a pointer deference into the interpreter structure under ithreads,
1307 and a global variable otherwise.
1311 C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()> on
1312 the scalar. It now updates the linked list to remove each piece of magic
1317 Under ithreads, the regex in C<PL_reg_curpm> is now reference counted. This
1318 eliminates a lot of hackish workarounds to cope with it not being reference
1323 C<Perl_mg_magical()> would sometimes incorrectly turn on C<SvRMAGICAL()>.
1324 This has been fixed.
1328 The I<public> IV and NV flags are now not set if the string value has
1329 trailing "garbage". This behaviour is consistent with not setting the
1330 public IV or NV flags if the value is out of range for the type.
1334 SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
1335 The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
1336 that was enabled when the F<perl> binary was compiled.
1340 Smartmatch resolution tracing has been added as a new diagnostic. Use C<-DM> to
1345 A new debugging flag C<-DB> now dumps subroutine definitions, leaving
1346 C<-Dx> for its original purpose of dumping syntax trees.
1350 Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have been
1351 replaced by C<NULL> in the core code, and non-dual-life modules, as C<NULL>
1352 is clearer to those unfamiliar with the core code.
1356 A macro C<MUTABLE_PTR(p)> has been added, which on (non-pedantic) gcc will
1357 not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
1358 C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
1359 casting away C<const>. This allows proper compile-time auditing of
1360 C<const> correctness in the core, and helped picked up some errors (now
1365 Macros C<mPUSHs()> and C<mXPUSHs()> have been added, for pushing SVs on the
1366 stack and mortalizing them.
1370 Use of the private structure C<mro_meta> has changed slightly. Nothing
1371 outside the core should be accessing this directly anyway.
1375 A new tool, F<Porting/expand-macro.pl> has been added, that allows you
1376 to view how a C preprocessor macro would be expanded when compiled.
1377 This is handy when trying to decode the macro hell that is the perl
1386 Many modules updated from CPAN incorporate new tests.
1387 Several tests that have the potential to hang forever if they fail now
1388 incorporate a "watchdog" functionality that will kill them after a timeout,
1389 which helps ensure that C<make test> and C<make test_harness> run to
1390 completion automatically. (Jerry Hedden).
1392 Some core-specific tests have been added:
1398 Significant cleanups to core tests to ensure that language and
1399 interpreter features are not used before they're tested.
1403 C<make test_porting> now runs a number of important pre-commit checks which might be of use to anyone working on the Perl core.
1407 F<t/porting/podcheck.t> automatically checks the well-formedness of
1408 POD found in all .pl, .pm and .pod files in the F<MANIFEST>, other than in
1409 dual-lifed modules which are primarily maintained outside the Perl core.
1413 F<t/porting/manifest.t> now tests that all files listed in MANIFEST are present.
1417 F<t/op/while_readdir.t>
1419 Test that a bare readdir in while loop sets $_.
1423 t/comp/retainedlines.t
1425 Check that the debugger can retain source lines from C<eval>.
1431 Check that bad layers fail.
1437 Check that PerlIO layers are not leaking.
1443 Check that certain special forms of open work.
1449 General PerlIO tests.
1455 Check that there is no unexpected interaction between the internal types
1456 C<PVBM> and C<PVGV>.
1460 t/mro/package_aliases.t
1462 Check that mro works properly in the presence of aliased packages.
1468 Tests for C<dbmopen> and C<dbmclose>.
1474 Tests for the interaction of C<index> and threads.
1480 Tests for the interaction of esoteric patterns and threads.
1486 Test that C<qr> doesn't leak.
1490 t/op/reg_email_thr.t
1492 Tests for the interaction of regex recursion and threads.
1496 t/op/regexp_qr_embed_thr.t
1498 Tests for the interaction of patterns with embedded C<qr//> and threads.
1502 t/op/regexp_unicode_prop.t
1504 Tests for Unicode properties in regular expressions.
1508 t/op/regexp_unicode_prop_thr.t
1510 Tests for the interaction of Unicode properties and threads.
1516 Test the tied methods of C<Tie::Hash::NamedCapture>.
1522 Check that POSIX character classes behave consistently.
1528 Check that exportable C<re> functions in F<universal.c> work.
1534 Check that C<setpgrp> works.
1540 Tests for the interaction of C<substr> and threads.
1546 Check that upgrading and assigning scalars works.
1552 Check that Unicode in the lexer works.
1558 Check that Unicode and C<tie> work.
1562 t/comp/final_line_num.t
1564 See if line numbers are correct at EOF
1570 See if format scoping works
1576 See if @{"_<$file"} works
1582 See if -t file test works
1594 Tests malfunctions of utf8 cache
1600 Test unicode \p{} regex constructs
1604 =head2 Testing improvements
1610 It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
1615 =head1 New or Changed Diagnostics
1617 Several new diagnostics, see L<perldiag> for details.
1623 C<Bad plugin affecting keyword '%s'>
1627 C<gmtime(%.0f) too large>
1631 C<Lexing code attempted to stuff non-Latin-1 character into Latin-1 input>
1635 C<Lexing code internal error (%s)>
1639 C<localtime(%.0f) too large>
1643 C<Overloaded dereference did not return a reference>
1647 C<Overloaded qr did not return a REGEXP>
1651 C<Perl_pmflag() is deprecated, and will be removed from the XS API>
1655 New warning category C<illegalproto>
1659 Illegal character in prototype for %s : %s
1660 Prototype after '%c' for %s : %s
1662 have been moved from the C<syntax> top-level warnings category into a new
1663 first-level category, C<illegalproto>. These two warnings are currently the
1664 only ones emitted during parsing of an invalid/illegal prototype, so one
1667 no warnings 'illegalproto';
1669 to suppress only those, but not other syntax-related warnings. Warnings where
1670 prototypes are changed, ignored, or not met are still in the C<prototype>
1671 category as before. (Matt S. Trout)
1675 lvalue attribute ignored after the subroutine has been defined
1677 This new warning is issued when one attempts to mark a subroutine as
1678 lvalue after it has been defined.
1682 warn if ++ or -- are unable to change the value because it's beyond the limit of representation
1684 This uses a new warnings category: "imprecision".
1687 lc/uc/lcfirst/ucfirst warn when passed undef.
1691 Show constant in "Useless use of a constant in void context"
1695 Make the new warning report undef constants as undef
1699 Add a new warning, "Prototype after '%s'"
1703 Tweak the "Illegal character in prototype" warning so it's more precise when reporting illegal characters after _
1707 Unintended interpolation of $\ in regex
1711 Make overflow warnings in gmtime/localtime only occur when warnings are on
1715 Improve mro merging error messages.
1717 They are now very similar to those produced by Algorithm::C3.
1721 Amelioration of the error message "Unrecognized character %s in column %d"
1723 Changes the error message to "Unrecognized character %s; marked by E<lt>--
1724 HERE after %sE<lt>-- HERE near column %d". This should make it a little
1725 simpler to spot and correct the suspicious character.
1729 Explicitely point to $. when it causes an uninitialized warning for ranges in scalar context
1733 One diagnostic has been removed:
1741 C<split> now warns when called in void context
1745 C<printf>-style functions called with too few arguments will now issue the
1746 warning C<"Missing argument in %s"> [perl #71000]
1750 C<panic: sv_chop %s>
1752 This new fatal error occurs when the C routine C<Perl_sv_chop()> was
1753 passed a position that is not within the scalar's string buffer. This
1754 could be caused by buggy XS code, and at this point recovery is not
1759 C<Can't locate package %s for the parents of %s>
1761 This warning has been removed. In general, it only got produced in
1762 conjunction with other warnings, and removing it allowed an ISA lookup
1763 optimisation to be added.
1767 C<v-string in use/require is non-portable>
1769 This warning has been removed.
1773 C<Deep recursion on subroutine "%s">
1775 It is now possible to change the depth threshold for this warning from the
1776 default of 100, by recompiling the F<perl> binary, setting the C
1777 pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
1781 Perl now properly returns a syntax error instead of segfaulting
1782 if C<each>, C<keys> or C<values> is used without an argument
1786 C<tell()> now fails properly if called without an argument and when no previous file was read
1788 C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring the 5.8.x behaviour
1792 overload no longer implicitly unsets fallback on repeated 'use overload' lines
1796 POSIX::strftime() can now handle Unicode characters in the format string.
1800 The Windows select() implementation now supports all empty C<fd_set>s more correctly.
1804 The 'syntax' category was removed from 5 warnings that should only be in 'deprecated'.
1808 Three fatal pack/unpack error messages have been normalized to "panic: %s"
1812 "Unicode character is illegal" has been rephrased to be more accurate
1814 It now reads C<Unicode non-character is illegal in interchange> and the
1815 perldiag documentation has been expanded a bit.
1819 Perl now defaults to issuing a warning if a deprecated language feature is used.
1821 To disable this feature in a given lexical scope, you should use C<no
1822 warnings 'deprecated';> For information about which language features
1823 are deprecated and explanations of various deprecation warnings, please
1828 =head1 Utility Changes
1836 Now looks in C<include-fixed> too, which is a recent addition to gcc's
1843 No longer incorrectly treats enum values like macros (Daniel Burr).
1845 Now handles C++ style constants (C<//>) properly in enums. (A patch from
1846 Rainer Weikusat was used; Daniel Burr also proposed a similar fix).
1852 C<LVALUE> subroutines now work under the debugger.
1854 The debugger now correctly handles proxy constant subroutines, and
1861 F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out upstream bug
1864 Where the user names a module that their bug report is about, and we know the
1865 URL for its upstream bug tracker, provide a message to the user explaining
1866 that the core copies the CPAN version directly, and provide the URL for
1867 reporting the bug directly to upstream.
1873 Perl 5.11.0 added a new utility F<perlthanks>, which is a variant of
1874 F<perlbug>, but for sending non-bug-reports to the authors and maintainers
1875 of Perl. Getting nothing but bug reports can become a bit demoralising:
1876 we'll see if this changes things.
1882 No longer reports "Message sent" when it hasn't actually sent the message
1888 Fixed bugs with the match() operator in list context, remove mention of
1893 =head1 Selected Bug Fixes
1899 Ensure that pp_qr returns a new regexp SV each time. Resolves RT #69852.
1901 Instead of returning a(nother) reference to the (pre-compiled) regexp in the
1902 optree, use reg_temp_copy() to create a copy of it, and return a reference to
1903 that. This resolves issues about Regexp::DESTROY not being called in a timely
1904 fashion (the original bug tracked by RT #69852), as well as bugs related to
1905 blessing regexps, and of assigning to regexps, as described in correspondence
1906 added to the ticket.
1908 It transpires that we also need to undo the SvPVX() sharing when ithreads
1909 cloning a Regexp SV, because mother_re is set to NULL, instead of a cloned
1910 copy of the mother_re. This change might fix bugs with regexps and threads in
1911 certain other situations, but as yet neither tests nor bug reports have
1912 indicated any problems, so it might not actually be an edge case that it's
1919 Several compilation errors and segfaults when perl was built with C<-Dmad> were fixed.
1923 Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.
1927 F<-t> should only return TRUE for file handles connected to a TTY
1929 The Microsoft C version of isatty() returns TRUE for all
1930 character mode devices, including the /dev/null style "nul"
1931 device and printers like "lpt1".
1935 Fixed a regression caused by commit fafafbaf which caused a panic during
1936 parameter passing [perl #70171]
1940 On systems which in-place edits without backup files, -i'*' now works as
1941 the documentation says it does [perl #70802]
1945 Saving and restoring magic flags no longer loses readonly flag.
1949 The malformed syntax C<grep EXPR LIST> (note the missing comma) no longer
1950 causes abrupt and total failure.
1954 Regular expressions compiled with C<qr{}> literals properly set C<$'> when
1959 Using named subroutines with C<sort> should no longer lead to bus errors [perl
1964 Numerous bugfixes catch small issues caused by the recently-added Lexer API.
1968 Smart match against C<@_> sometimes gave false negatives. [perl #71078]
1972 C<$@> may now be assigned a read-only value (without error or busting the stack).
1976 C<sort> called recursively from within an active comparison subroutine no
1977 longer causes a bus error if run multiple times. [perl #71076]
1981 Tie::Hash::NamedCapture::* shouldn't abort if passed bad input (RT #71828)
1985 @_ and $_ no longer leak under threads (RT #34342 and #41138, also
1990 C<-I> on shebang line now adds directories in front of @INC
1991 as documented, and as does C<-I> when specified on the command-line.
1995 C<kill> is now fatal when called on non-numeric process identifiers.
1996 Previously, an 'undef' process identifier would be interpreted as a request to
1997 kill process "0", which would terminate the current process group on POSIX
1998 systems. Since process identifiers are always integers, killing a non-numeric
1999 process is now fatal.
2003 5.10.0 inadvertently disabled an optimisation, which caused a measurable
2004 performance drop in list assignment, such as is often used to assign
2005 function parameters from C<@_>. The optimisation has been re-instated, and
2006 the performance regression fixed.
2010 Fixed memory leak on C<while (1) { map 1, 1 }> [RT #53038].
2014 Some potential coredumps in PerlIO fixed [RT #57322,54828].
2018 The debugger now works with lvalue subroutines.
2022 The debugger's C<m> command was broken on modules that defined constants
2027 C<crypt> and string complement could return tainted values for untainted
2028 arguments [RT #59998].
2032 The C<-i>I<.suffix> command-line switch now recreates the file using
2033 restricted permissions, before changing its mode to match the original
2034 file. This eliminates a potential race condition [RT #60904].
2038 On some Unix systems, the value in C<$?> would not have the top bit set
2039 (C<$? & 128>) even if the child core dumped.
2043 Under some circumstances, C<$^R> could incorrectly become undefined
2048 In the XS API, various hash functions, when passed a pre-computed hash where
2049 the key is UTF-8, might result in an incorrect lookup.
2053 XS code including F<XSUB.h> before F<perl.h> gave a compile-time error
2058 C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo> didn't
2059 exist, even if the object's C<@ISA> contained C<Foo>.
2063 Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
2064 C<@ISA>, have been found and fixed.
2068 Bitwise operations on references could crash the interpreter, e.g.
2069 C<$x=\$y; $x |= "foo"> [RT #54956].
2073 Patterns including alternation might be sensitive to the internal UTF-8
2074 representation, e.g.
2076 my $byte = chr(192);
2077 my $utf8 = chr(192); utf8::upgrade($utf8);
2078 $utf8 =~ /$byte|X}/i; # failed in 5.10.0
2082 Within UTF8-encoded Perl source files (i.e. where C<use utf8> is in
2083 effect), double-quoted literal strings could be corrupted where a C<\xNN>,
2084 C<\0NNN> or C<\N{}> is followed by a literal character with ordinal value
2085 greater than 255 [RT #59908].
2089 C<B::Deparse> failed to correctly deparse various constructs:
2090 C<readpipe STRING> [RT #62428], C<CORE::require(STRING)> [RT #62488],
2091 C<sub foo(_)> [RT #62484].
2095 Using C<setpgrp> with no arguments could corrupt the perl stack.
2099 The block form of C<eval> is now specifically trappable by C<Safe> and
2100 C<ops>. Previously it was erroneously treated like string C<eval>.
2104 In 5.10.0, the two characters C<[~> were sometimes parsed as the smart
2105 match operator (C<~~>) [RT #63854].
2109 In 5.10.0, the C<*> quantifier in patterns was sometimes treated as
2110 C<{0,32767}> [RT #60034, #60464]. For example, this match would fail:
2112 ("ab" x 32768) =~ /^(ab)*$/
2116 C<shmget> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].
2120 Using C<next> or C<last> to exit a C<given> block no longer produces a
2121 spurious warning like the following:
2123 Exiting given via last at foo.pl line 123
2127 On Windows, C<'.\foo'> and C<'..\foo'> were treated differently than
2128 C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
2132 Assigning a format to a glob could corrupt the format; e.g.:
2134 *bar=*foo{FORMAT}; # foo format now bad
2138 Attempting to coerce a typeglob to a string or number could cause an
2139 assertion failure. The correct error message is now generated,
2140 C<Can't coerce GLOB to I<$type>>.
2144 Under C<use filetest 'access'>, C<-x> was using the wrong access mode. This
2145 has been fixed [RT #49003].
2149 C<length> on a tied scalar that returned a Unicode value would not be
2150 correct the first time. This has been fixed.
2154 Using an array C<tie> inside in array C<tie> could SEGV. This has been
2159 A race condition inside C<PerlIOStdio_close()> has been identified and
2160 fixed. This used to cause various threading issues, including SEGVs.
2164 In C<unpack>, the use of C<()> groups in scalar context was internally
2165 placing a list on the interpreter's stack, which manifested in various
2166 ways, including SEGVs. This is now fixed [RT #50256].
2170 Magic was called twice in C<substr>, C<\&$x>, C<tie $x, $m> and C<chop>.
2171 These have all been fixed.
2175 A 5.10.0 optimisation to clear the temporary stack within the implicit
2176 loop of C<s///ge> has been reverted, as it turned out to be the cause of
2177 obscure bugs in seemingly unrelated parts of the interpreter [commit
2182 The line numbers for warnings inside C<elsif> are now correct.
2186 The C<..> operator now works correctly with ranges whose ends are at or
2187 close to the values of the smallest and largest integers.
2191 C<binmode STDIN, ':raw'> could lead to segmentation faults on some platforms.
2192 This has been fixed [RT #54828].
2196 An off-by-one error meant that C<index $str, ...> was effectively being
2197 executed as C<index "$str\0", ...>. This has been fixed [RT #53746].
2201 Various leaks associated with named captures in regexes have been fixed
2206 A weak reference to a hash would leak. This was affecting C<DBI>
2211 Using (?|) in a regex could cause a segfault [RT #59734].
2215 Use of a UTF-8 C<tr//> within a closure could cause a segfault [RT #61520].
2219 Calling C<Perl_sv_chop()> or otherwise upgrading an SV could result in an
2220 unaligned 64-bit access on the SPARC architecture [RT #60574].
2224 In the 5.10.0 release, C<inc_version_list> would incorrectly list
2225 C<5.10.*> after C<5.8.*>; this affected the C<@INC> search order
2230 In 5.10.0, C<pack "a*", $tainted_value> returned a non-tainted value
2235 In 5.10.0, C<printf> and C<sprintf> could produce the fatal error
2236 C<panic: utf8_mg_pos_cache_update> when printing UTF-8 strings
2241 In the 5.10.0 release, a dynamically created C<AUTOLOAD> method might be
2242 missed (method cache issue) [RT #60220,60232].
2246 In the 5.10.0 release, a combination of C<use feature> and C<//ee> could
2247 cause a memory leak [RT #63110].
2251 C<-C> on the shebang (C<#!>) line is once more permitted if it is also
2252 specified on the command line. C<-C> on the shebang line used to be a
2253 silent no-op I<if> it was not also on the command line, so perl 5.10.0
2254 disallowed it, which broke some scripts. Now perl checks whether it is
2255 also on the command line and only dies if it is not [RT #67880].
2259 In 5.10.0, certain types of re-entrant regular expression could crash,
2260 or cause the following assertion failure [RT #60508]:
2262 Assertion rx->sublen >= (s - rx->subbeg) + i failed
2266 Previously missing files from Unicode 5.1 Character Database are now included.
2270 C<TMPDIR> is now honored when opening an anonymous temporary file
2274 =head1 Platform Specific Changes
2276 =head2 New Platforms
2282 Patches from the Haiku maintainers have been merged in. Perl should now
2287 Perl should now build on MirOS BSD.
2292 =head2 Discontinued Platforms
2298 Support for Apollo DomainOS was removed in Perl 5.11.0
2302 Support for Tenon Intersystems MachTen Unix layer for MacOS Classic was
2303 removed in Perl 5.11.0
2307 Support for Atari MiNT was removed in Perl 5.11.0.
2311 =head2 Updated Platforms
2315 =item Darwin (Mac OS X)
2321 Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
2322 as it's still buggy.
2326 Correct infelicities in the regexp used to identify buggy locales
2327 on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).
2337 Fix thread library selection [perl #69686]
2347 Initial support for mingw64 is now available
2351 Various bits of Perl's build infrastructure are no longer converted to win32 line endings at release time. If this hurts you, please speak up.
2355 Always add a manifest resource to C<perl.exe> to specify the C<trustInfo>
2356 settings for Windows Vista and later. Without this setting Windows
2357 will treat C<perl.exe> as a legacy application and apply various
2358 heuristics like redirecting access to protected file system areas
2359 (like the "Program Files" folder) to the users "VirtualStore"
2360 instead of generating a proper "permission denied" error.
2362 For VC8 and VC9 this manifest setting is automatically generated by
2363 the compiler/linker (together with the binding information for their
2364 respective runtime libraries); for all other compilers we need to
2365 embed the manifest resource explicitly in the external resource file.
2367 This change also requests the Microsoft Common-Controls version 6.0
2368 (themed controls introduced in Windows XP) via the dependency list
2369 in the assembly manifest. For VC8 and VC9 this is specified using the
2370 C</manifestdependency> linker commandline option instead.
2374 Improved message window handling means that C<alarm> and C<kill> messages
2375 will no longer be dropped under race conditions.
2385 Enable IPv6 support on cygwin 1.7 and newer
2395 Make -UDEBUGGING the default on VMS for 5.12.0.
2397 Like it has been everywhere else for ages and ages. Also make
2398 command-line selection of -UDEBUGGING and -DDEBUGGING work in
2399 configure.com; before the only way to turn it off was by saying
2400 no in answer to the interactive question.
2404 The default pipe buffer size on VMS has been updated to 8192 on 64-bit
2409 Reads from the in-memory temporary files of C<PerlIO::scalar> used to fail
2410 if C<$/> was set to a numeric reference (to indicate record-style reads).
2415 VMS now supports C<getgrgid>.
2419 Many improvements and cleanups have been made to the VMS file name handling
2420 and conversion code.
2424 Enabling the C<PERL_VMS_POSIX_EXIT> logical name now encodes a POSIX exit
2425 status in a VMS condition value for better interaction with GNV's bash
2426 shell and other utilities that depend on POSIX exit values. See
2427 L<perlvms/"$?"> for details.
2431 C<File::Copy> now detects Unix compatibility mode on VMS.
2437 Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from F<libbsd>.
2439 Removed F<libgdbm> for AIX 5L and 6.1. The F<libgdbm> is delivered as an
2440 optional package with the AIX Toolbox. Unfortunately the 64 bit version
2443 Hints changes mean that AIX 4.2 should work again.
2447 On Cygwin we now strip the last number from the DLL. This has been the
2448 behaviour in the cygwin.com build for years. The hints files have been
2454 The hints files now identify the correct threading libraries on FreeBSD 7
2459 We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
2460 C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
2464 Hints now supports versions 5.*.
2468 Various changes from Stratus have been merged in.
2472 There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
2476 =head1 Known Problems
2478 This is a list of some significant unfixed bugs, which are regressions
2479 from either 5.10.0 or 5.8.x.
2485 C<List::Util::first> misbehaves in the presence of a lexical C<$_>
2486 (typically introduced by C<my $_> or implicitly by C<given>). The variable
2487 which gets set for each iteration is the package variable C<$_>, not the
2488 lexical C<$_> [RT #67694].
2490 A similar issue may occur in other modules that provide functions which
2491 take a block as their first argument, like
2493 foo { ... $_ ...} list
2497 The C<charnames> pragma may generate a run-time error when a regex is
2498 interpolated [RT #56444]:
2500 use charnames ':full';
2501 my $r1 = qr/\N{THAI CHARACTER SARA I}/;
2502 "foo" =~ $r1; # okay
2503 "foo" =~ /$r1+/; # runtime error
2505 A workaround is to generate the character outside of the regex:
2507 my $a = "\N{THAI CHARACTER SARA I}";
2512 Some regexes may run much more slowly when run in a child thread compared
2513 with the thread the pattern was compiled into [RT #55600].
2517 Perl 5.11.4 is a development release leading up to Perl 5.12.0.
2518 Some notable known problems found in 5.11.4 are listed as dependencies
2519 of RT #69710, the Perl 5 version 12 meta-ticket.
2523 Untriaged test crashes on Windows 2000
2525 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.
2529 Known test failures on VMS
2531 Perl 5.11.1 fails a small set of core and CPAN tests as of this release.
2532 With luck, that'll be sorted out for 5.11.2
2536 Known test failures on VMS
2538 Perl 5.11.2 fails a small set of core and CPAN tests as of this
2539 release. With luck, that'll be sorted out for 5.11.3.
2543 =head1 Acknowledgements
2545 Perl 5.12.0 represents approximately two years of development since
2546 Perl 5.10.0 and contains __ lines of changes across ___ files
2547 from __ authors and committers:
2551 Many of the changes included in this version originated in the CPAN
2552 modules included in Perl's core. We're grateful to the entire CPAN
2553 community for helping Perl to flourish.
2555 =head1 Reporting Bugs
2557 If you find what you think is a bug, you might check the articles
2558 recently posted to the comp.lang.perl.misc newsgroup and the perl
2559 bug database at L<http://rt.perl.org/perlbug/>. There may also be
2560 information at L<http://www.perl.org/>, the Perl Home Page.
2562 If you believe you have an unreported bug, please run the B<perlbug>
2563 program included with your release. Be sure to trim your bug down
2564 to a tiny but sufficient test case. Your bug report, along with the
2565 output of C<perl -V>, will be sent off to perlbug@perl.org to be
2566 analyzed by the Perl porting team.
2568 If the bug you are reporting has security implications, which make it
2569 inappropriate to send to a publicly archived mailing list, then please send
2570 it to perl5-security-report@perl.org. This points to a closed subscription
2571 unarchived mailing list, which includes all the core committers, who be able
2572 to help assess the impact of issues, figure out a resolution, and help
2573 co-ordinate the release of patches to mitigate or fix the problem across all
2574 platforms on which Perl is supported. Please only use this address for
2575 security issues in the Perl core, not for modules independently
2576 distributed on CPAN.
2580 The F<Changes> file for an explanation of how to view exhaustive details
2583 The F<INSTALL> file for how to build Perl.
2585 The F<README> file for general stuff.
2587 The F<Artistic> and F<Copying> files for copyright information.