5 perl5215delta - what is new for perl v5.21.5
9 This document describes differences between the 5.21.4 release and the 5.21.5
12 If you are upgrading from an earlier release such as 5.21.3, first read
13 L<perl5214delta>, which describes differences between 5.21.3 and 5.21.4.
15 =head1 Core Enhancements
17 =head2 New double-diamond operator
19 C<<< <<>> >>> is like C<< <> >> but uses three-argument C<open> to open
20 each file in @ARGV. So each element of @ARGV is an actual file name, and
21 "|foo" won't be treated as a pipe open.
23 =head2 Aliasing via reference
25 Variables and subroutines can now be aliased by assigning to a reference:
30 Or by using a backslash before a C<foreach> iterator variable, which is
31 perhaps the most useful idiom this feature provides:
33 foreach \%hash (@array_of_hash_refs) { ... }
35 This feature is experimental and must be enabled via C<use feature
36 'refaliasing'>. It will warn unless the C<experimental::refaliasing>
37 warnings category is disabled.
39 See L<perlref/Assigning to References>
41 =head2 Perl now supports POSIX 2008 locale currency additions.
43 On platforms that are able to handle POSIX.1-2008, the
45 L<C<POSIX::localeconv()>|perllocale/The localeconv function>
46 includes the international currency fields added by that version of the
47 POSIX standard. These are
49 C<int_n_sep_by_space>,
52 C<int_p_sep_by_space>,
56 =head2 Packing infinity or not-a-number into a character is now fatal
58 Before, when trying to pack infinity or not-a-number into a
59 (signed) character, Perl would warn, and assumed you tried to
60 pack C<< 0xFF >>; if you gave it as an argument to C<< chr >>,
61 C<< U+FFFD >> was returned.
63 But now, all such actions (C<< pack >>, C<< chr >>, and C<< print '%c' >>)
64 result in a fatal error.
68 Many small improvements, bug fixes and added test cases for dealing
69 with math related to infinity and not-a-number.
73 =head2 Perl is now compiled with -fstack-protector-strong if available
75 Perl has been compiled with the anti-stack-smashing option
76 C<-fstack-protector> since 5.10.1. Now Perl uses the newer variant
77 called C<-fstack-protector-strong>, if available. (This was added
82 =head2 Use of multiple /x regexp modifiers
84 It is now deprecated to say something like any of the following:
90 That is, now C<x> should only occur once in any string of contiguous
91 regular expression pattern modifiers. We do not believe there are any
92 occurrences of this in all of CPAN. This is in preparation for a future
93 Perl release having C</xx> mean to allow white-space for readability in
94 bracketed character classes (those enclosed in square brackets:
97 =head1 Performance Enhancements
103 C<length> is up to 20% faster for non-magical/non-tied scalars containing a
104 string if it is a non-utf8 string or if C<use bytes;> is in scope.
108 Non-magical/non-tied scalars that contain only a floating point value and are
109 on most Perl builds with 64 bit integers now use 8-32 less bytes of memory
114 In C<@array = split>, the assignment can be optimized away with C<split>
115 writing directly to the array. This optimisation was happening only for
116 package arrays other than @_ and only
117 sometimes. Now this optimisation happens
122 C<join> is now subject to constant folding. Moreover, C<join> with a
123 scalar or constant for the separator and a single-item list to join is
124 simplified to a stringification. The separator doesn't even get evaluated.
128 C<qq(@array)> is implemented using two ops: a stringify op and a join op.
129 If the qq contains nothing but a single array, the stringification is
134 C<our $var> and C<our($s,@a,%h)> in void context are no longer evaluated at
135 run time. Even a whole sequence of C<our $foo;> statements will simply be
136 skipped over. The same applies to C<state> variables.
140 =head1 Modules and Pragmata
142 =head2 Updated Modules and Pragmata
148 L<attributes> has been upgraded from version 0.23 to 0.24.
150 Avoid reading beyond the end of a buffer. [perl #122629]
154 L<B> has been upgraded from version 1.51 to 1.52.
158 L<B::Concise> has been upgraded from version 0.993 to 0.994.
160 Null ops that are part of the execution chain are now given sequence
163 Private flags for nulled ops are now dumped with mnemonics as they would be
164 for the non-nulled counterparts.
166 L<B::Deparse> has been upgraded from version 1.28 to 1.29.
168 Parenthesised arrays in lists passed to C<\> are now correctly deparsed
169 with parentheses (e.g., C<\(@a, (@b), @c)> now retains the parentheses
170 around @b), this preserving the flattening behaviour of referenced
171 parenthesised arrays. Formerly, it only worked for one array: C<\(@a)>.
173 C<local our> is now deparsed correctly, with the C<our> included.
175 C<for($foo; !$bar; $baz) {...}> was deparsed without the C<!> (or C<not>).
178 Core keywords that conflict with lexical subroutines are now deparsed with
179 the C<CORE::> prefix.
181 C<foreach state $x (...) {...}> now deparses correctly with C<state> and
184 C<our @array = split(...)> now deparses correctly with C<our> in those
185 cases where the assignment is optimized away.
189 L<B::Debug> has been upgraded from version 1.21 to 1.22.
193 L<B::Deparse> has been upgraded from version 1.28 to 1.29.
197 L<Compress::Raw::Bzip2> has been upgraded from version 2.064 to 2.066.
201 L<Compress::Raw::Zlib> has been upgraded from version 2.065 to 2.066.
205 L<CPAN::Meta> has been upgraded from version 2.142060 to 2.142690.
209 L<DynaLoader> has been upgraded from version 1.26 to 1.27.
211 Remove dl_nonlazy global if unused in Dynaloader. [perl #122926]
215 L<Errno> has been upgraded from version 1.20_04 to 1.21.
219 L<experimental> has been upgraded from version 0.010 to 0.012.
223 L<ExtUtils::CBuilder> has been upgraded from version 0.280219 to 0.280220.
227 L<ExtUtils::Miniperl> has been upgraded from version 1.02 to 1.03.
231 L<Fcntl> has been upgraded from version 1.11 to 1.13.
233 Add support for the Linux pipe buffer size fcntl() commands.
237 L<feature> has been upgraded from version 1.37 to 1.38.
241 L<File::Find> has been upgraded from version 1.28 to 1.29.
243 Slightly faster module loading time.
247 L<File::Spec> has been upgraded from version 3.50 to 3.51.
251 L<HTTP::Tiny> has been upgraded from version 0.049 to 0.050.
255 The IO-Compress set of modules has been upgraded from version 2.064 to 2.066.
259 L<JSON::PP> has been upgraded from version 2.27203 to 2.27300.
263 The libnet collection of modules has been upgraded from version 1.27 to 3.02.
265 Support for IPv6 and SSL to Net::FTP, Net::NNTP, Net::POP3 and Net::SMTP.
267 Improvements in Net::SMTP authentication.
271 L<Module::CoreList> has been upgraded from version 5.20140920 to 5.20141020.
273 Updated to cover the latest releases of Perl.
277 L<Opcode> has been upgraded from version 1.28 to 1.29.
281 The PathTools module collection has been upgraded from version 3.50 to 3.51.
283 Slightly faster module loading time.
287 L<perlfaq> has been upgraded from version 5.0150045 to version 5.0150046.
292 L<POSIX> has been upgraded from version 1.43 to 1.45.
294 POSIX::tmpnam() now produces a deprecation warning. [perl #122005]
298 L<re> has been upgraded from version 0.26 to 0.27.
302 L<Socket> has been upgraded from version 2.015 to 2.016.
306 L<Test::Simple> has been upgraded from version 1.001006 to 1.001008.
310 L<threads::shared> has been upgraded from version 1.46 to 1.47.
314 L<warnings> has been upgraded from version 1.26 to 1.28.
318 L<XSLoader> has been upgraded from version 0.17 to 0.18.
320 Allow XSLoader to load modules from a different namespace.
327 =head2 Changes to Existing Documentation
329 =head3 L<perlrecharclass>
335 Clarifications have been added to L<perlrecharclass/Character Ranges>
336 to the effect that Perl guarantees that C<[A-Z]>, C<[a-z]>, C<[0-9]> and
337 any subranges thereof in regular expression bracketed character classes
338 are guaranteed to match exactly what a naive English speaker would
339 expect them to match, even on platforms (such as EBCDIC) where special
340 handling is required to accomplish this.
346 The following additions or changes have been made to diagnostic output,
347 including warnings and fatal error messages. For the complete list of
348 diagnostic messages, see L<perldiag>.
350 =head2 New Diagnostics
358 L<Cannot chr %f|perldiag/"Cannot chr %f">
362 L<Cannot compress %f in pack|perldiag/"Cannot compress %f in pack">
366 L<Cannot pack %f with '%c'|perldiag/"Cannot pack %f with '%c'">
370 L<Cannot print %f with '%c'|perldiag/"Cannot printf %f with '%c'">
374 =head2 Changes to Existing Diagnostics
380 '"my" variable &foo::bar can't be in a package' has been reworded to say
381 'subroutine' instead of 'variable'.
391 Some regular expression tests are written in such a way that they will
392 run very slowly if certain optimizations break. These tests have been
393 moved into new files, F<< t/re/speed.t >> and F<< t/re/speed_thr.t >>,
394 and are run with a C<< watchdog() >>.
398 =head1 Platform Support
400 =head2 Regained Platforms
402 IRIX and Tru64 platforms are working again.
403 (Some C<make test> failures remain.)
405 =head2 Platform-Specific Notes
411 Special handling is required on EBCDIC platforms to get C<qr/[i-j]/> to
412 match only C<"i"> and C<"j">, since there are 7 characters between the
413 code points for C<"i"> and C<"j">. This special handling had only been
414 invoked when both ends of the range are literals. Now it is also
415 invoked if any of the C<\N{...}> forms for specifying a character by
416 name or Unicode code point is used instead of a literal. See
417 L<perlrecharclass/Character Ranges>.
421 =head1 Internal Changes
427 SVs of type SVt_NV are now bodyless when a build configure and platform allow
428 it, specifically C<sizeof(NV) <= sizeof(IV)>. The bodyless trick is the same one
429 as for IVs since 5.9.2, but for NVs, unlike IVs, is not guaranteed on all
430 platforms and build configurations.
434 The C<$DB::single>, C<$DB::signal> and C<$DB::trace> now have set and
435 get magic that stores their values as IVs and those IVs are used when
436 testing their values in C<pp_dbstate>. This prevents perl from
437 recursing infinity if an overloaded object is assigned to any of those
438 variables. [perl #122445]
442 C<Perl_tmps_grow> which is marked as public API but undocumented has been
443 removed from public API. If you use C<EXTEND_MORTAL> macro in your XS code to
444 preextend the mortal stack, you are unaffected by this change.
448 C<cv_name>, which was introduced in 5.21.4, has been changed incompatibly.
449 It now has a flags field that allows the caller to specify whether the name
450 should be fully qualified. See L<perlapi/cv_name>.
454 Internally Perl no longer uses the C<SVs_PADMY> flag. C<SvPADMY()> now
455 returns a true value for anything not marked PADTMP. C<SVs_PADMY> is now
460 The macros SETsv and SETsvUN have been removed. They were no longer used
461 in the core since commit 6f1401dc2a, and have not been found present on
466 The C<< SvFAKE >> bit (unused on HVs) got informally reserved by
467 David Mitchell for future work on vtables.
471 The C<sv_catpvn_flags> function accepts C<SV_CATBYTES> and C<SV_CATUTF8>
472 flags, which specify whether the appended string is bytes or utf8,
477 A new opcode class, C<< METHOP >> has been introduced, which holds
478 class/method related info needed at runtime to improve performance
479 of class/object method calls.
481 C<< OP_METHOD >> and C<< OP_METHOD_NAMED >> are moved from being
482 C<< UNOP/SVOP >> to being C<< METHOP >>.
486 =head1 Selected Bug Fixes
492 Locking and unlocking values via L<Hash::Util> or C<Internals::SvREADONLY>
493 no longer has any effect on values that are read-only to begin.
494 Previously, unlocking such values could result in crashes, hangs or
495 other erratic behaviour.
499 The internal C<looks_like_number> function (which L<Scalar::Util> provides
500 access to) began erroneously to return true for "-e1" in 5.21.4, affecting
501 also C<-'-e1'>. This has been fixed.
505 The flip-flop operator (C<..> in scalar context) would return the same
506 scalar each time, unless the containing subroutine was called recursively.
507 Now it always returns a new scalar. [perl #122829]
511 Some unterminated C<(?(...)...)> constructs in regular expressions would
512 either crash or give erroneous error messages. C</(?(1)/> is one such
517 C<pack "w", $tied> no longer calls FETCH twice.
521 List assignments like C<($x, $z) = (1, $y)> now work correctly if $x and $y
522 have been aliased by C<foreach>.
526 Some patterns including code blocks with syntax errors, such as
527 C</ (?{(^{})/>, would hang or fail assertions on debugging builds. Now
532 An assertion failure when parsing C<sort> with debugging enabled has been
533 fixed. [perl #122771]
537 C<*a = *b; @a = split //, $b[1]> could do a bad read and produce junk
542 In C<() = @array = split>, the C<() => at the beginning no longer confuses
543 the optimizer, making it assume a limit of 1.
547 Fatal warnings no longer prevent the output of syntax errors.
552 Fixed a NaN double to long double conversion error on VMS. For quiet NaNs
553 (and only on Itanium, not Alpha) negative infinity instead of NaN was
558 Fixed the issue that caused C<< make distclean >> to leave files behind
559 that shouldn't. [perl #122820]
563 AIX now sets the length in C<< getsockopt >> correctly. [perl #120835],
564 [rt #91183], [rt #85570].
568 During the pattern optimization phase, we no longer recurse into
569 GOSUB/GOSTART when not SCF_DO_SUBSTR. This prevents the optimizer
570 to run "forever" and exhaust all memory. [perl #122283]
574 F<< t/op/crypt.t >> now performs SHA-256 algorithm if the default one
575 is disabled. [perl #121591]
579 Fixed an off-by-one error when setting the size of shared array.
584 Fixed a bug that could cause perl to execute an infinite loop during
585 compilation. [perl #122995]
589 =head1 Acknowledgements
591 Perl 5.21.5 represents approximately 4 weeks of development since Perl 5.21.4
592 and contains approximately 40,000 lines of changes across 530 files from 33
595 Excluding auto-generated files, documentation and release tools, there were
596 approximately 29,000 lines of changes to 390 .pm, .t, .c and .h files.
598 Perl continues to flourish into its third decade thanks to a vibrant community
599 of users and developers. The following people are known to have contributed the
600 improvements that became Perl 5.21.5:
602 Aaron Crane, Abigail, Alberto Simões, Andrew Fresh, Chris 'BinGOs' Williams,
603 Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, David Mitchell, Doug
604 Bell, Ed J, Father Chrysostomos, George Greer, Graham Knop, James E Keenan,
605 Jarkko Hietaniemi, Karen Etheridge, Karl Williamson, Leon Timmermans, Lukas
606 Mai, Niko Tyni, Peter Martini, Petr Písař, Rafael Garcia-Suarez, Reini Urban,
607 Ricardo Signes, Shlomi Fish, Steve Hay, syber, Tony Cook, Vincent Pit, Yves
608 Orton, Ævar Arnfjörð Bjarmason.
610 The list above is almost certainly incomplete as it is automatically generated
611 from version control history. In particular, it does not include the names of
612 the (very much appreciated) contributors who reported issues to the Perl bug
615 Many of the changes included in this version originated in the CPAN modules
616 included in Perl's core. We're grateful to the entire CPAN community for
617 helping Perl to flourish.
619 For a more complete list of all of Perl's historical contributors, please see
620 the F<AUTHORS> file in the Perl source distribution.
622 =head1 Reporting Bugs
624 If you find what you think is a bug, you might check the articles recently
625 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
626 https://rt.perl.org/ . There may also be information at
627 http://www.perl.org/ , the Perl Home Page.
629 If you believe you have an unreported bug, please run the L<perlbug> program
630 included with your release. Be sure to trim your bug down to a tiny but
631 sufficient test case. Your bug report, along with the output of C<perl -V>,
632 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
634 If the bug you are reporting has security implications, which make it
635 inappropriate to send to a publicly archived mailing list, then please send it
636 to perl5-security-report@perl.org. This points to a closed subscription
637 unarchived mailing list, which includes all the core committers, who will be
638 able to help assess the impact of issues, figure out a resolution, and help
639 co-ordinate the release of patches to mitigate or fix the problem across all
640 platforms on which Perl is supported. Please only use this address for
641 security issues in the Perl core, not for modules independently distributed on
646 The F<Changes> file for an explanation of how to view exhaustive details on
649 The F<INSTALL> file for how to build Perl.
651 The F<README> file for general stuff.
653 The F<Artistic> and F<Copying> files for copyright information.