5 perldelta - what is new for perl v5.19.1
9 This document describes differences between the 5.19.0 release and the 5.19.1
12 =head1 Core Enhancements
14 No new features have been added.
18 There are no new security issues.
20 =head1 Incompatible Changes
22 =head2 Most regex engine global state eliminated
24 As part of this series of fixes it was necessary to change the API of
25 Perl_re_intuit_start(). See L</Internal Changes> for more.
27 =head2 Locale decimal point character no longer leaks outside of S<C<use locale>> scope
29 This is actually a bug fix, but some code has come to rely on the bug
30 being present, so this change is listed here. The current locale that
31 the program is running under is not supposed to be visible to Perl code
32 except within the scope of a S<C<use locale>>. However, until now under
33 certain circumstances, the character used for a decimal point (often a
34 comma) leaked outside the scope. If your code is affected by this
35 change, simply add a S<C<use locale>>.
37 =head1 Performance Enhancements
43 Perl has a new copy-on-write mechanism that avoids the need to copy the
44 internal string buffer when assigning from one scalar to another. This
45 makes copying large strings appear much faster. Modifying one of the two
46 (or more) strings after an assignment will force a copy internally. This
47 makes it unnecessary to pass strings by reference for efficiency.
49 This feature was already available in 5.18.0, but wasn't enabled by
50 default. It is the default now, and so you no longer need build perl with
51 the F<Configure> argument:
53 -Accflags=PERL_NEW_COPY_ON_WRITE
55 It can be disabled (for now) in a perl build with:
61 =head1 Modules and Pragmata
63 =head2 Updated Modules and Pragmata
69 L<Archive::Tar> has been upgraded from version 1.90 to 1.92.
73 L<Attribute::Handlers> has been upgraded from version 0.94 to 0.95.
77 L<autodie> has been upgraded from version 2.13 to 2.19.
81 L<B> has been upgraded from version 1.42 to 1.43.
85 L<B::Concise> has been upgraded from version 0.95 to 0.96.
89 L<B::Deparse> has been upgraded from version 1.20 to 1.21.
91 C<foreach my $lexical> is now deparsed correctly with the B<-p> option.
94 The B<-l> option no longer puts form feeds in the middle of a line when
95 outputting C<map> and C<grep> blocks. [RT #117311]
97 Elements of C<%#>, such as C<$# {foo}> and C<${#}{foo}> are now deparsed
98 correctly. [RT #117531]
102 L<Benchmark> has been upgraded from version 1.15 to 1.16.
106 L<Carp> has been upgraded from version 1.29 to 1.30.
110 L<Compress::Raw::Bzip2> has been upgraded from version 2.060 to 2.061.
114 L<Compress::Raw::Zlib> has been upgraded from version 2.060 to 2.061.
118 L<Config::Perl::V> has been upgraded from version 0.17 to 0.18.
122 L<CPAN::Meta> has been upgraded from version 2.120921 to 2.131560.
126 L<Data::Dumper> has been upgraded from version 2.145 to 2.146.
130 L<DB> has been updated from 1.05 to 1.06 and L<perl5db.pl> from 1.39_10
133 The call depth allowed by default in the debugger is now 1000
138 L<DB_File> has been upgraded from version 1.827 to 1.828.
142 L<Encode> has been upgraded from version 2.49 to 2.51.
146 L<ExtUtils::Install> has been upgraded from version 1.59 to 1.60.
150 L<ExtUtils::MakeMaker> has been upgraded from version 6.66 to 6.68.
154 L<ExtUtils::ParseXS> has been upgraded from version 3.18 to 3.19.
158 L<File::Copy> has been upgraded from version 2.26 to 2.27.
162 L<File::DosGlob> has been upgraded from version 1.10 to 1.11.
166 L<File::Fetch> has been upgraded from version 0.38 to 0.42.
170 L<File::Find> has been upgraded from version 1.23 to 1.24.
174 L<File::Spec> has been upgraded from version 3.40 to 3.41.
176 C<tmpdir> now respects changes to environment variables from which the
177 temporary directory is derived. [RT #88940]
181 L<File::Temp> has been upgraded from version 0.23 to 0.2301.
185 L<Filter::Simple> has been upgraded from version 0.89 to 0.90.
189 L<Filter::Util::Call> has been upgraded from version 1.45 to 1.49.
193 L<Getopt::Long> has been upgraded from version 2.39 to 2.4.
197 L<Hash::Util::FieldHash> has been upgraded from version 1.10 to 1.11.
201 L<HTTP::Tiny> has been upgraded from version 0.025 to 0.031.
205 L<IPC::Open3> has been upgraded from version 1.13 to 1.14.
209 L<Locale::Maketext> has been upgraded from version 1.23 to 1.24.
213 L<Math::BigInt> has been upgraded from version 1.9991 to 1.9992.
217 L<Math::BigRat> has been upgraded from version 0.2604 to 0.2606.
221 L<Module::Build> has been upgraded from version 0.4003 to 0.4005.
225 L<Module::CoreList> has been upgraded from version 2.91 to 2.92.
227 Adds L<Module::CoreList::Utils> which provides information on which core and
228 dual-life utilities shipped with each version of L<perl>.
232 L<Module::Metadata> has been upgraded from version 1.000011 to 1.000014.
236 L<mro> has been upgraded from version 1.11 to 1.12.
240 L<Net::Ping> has been upgraded from version 2.41 to 2.42.
244 L<perlfaq> has been upgraded from version 5.0150042 to 5.0150043.
248 L<Pod::Html> has been upgraded from version 1.18 to 1.19.
252 L<Pod::Parser> has been upgraded from version 1.60 to 1.61.
256 L<Pod::Perldoc> has been upgraded from version 3.19 to 3.20.
260 L<Pod::Usage> has been upgraded from version 1.61 to 1.63.
264 L<POSIX> has been upgraded from version 1.32 to 1.33.
268 L<re> has been upgraded from version 0.23 to 0.25.
272 L<Safe> has been upgraded from version 2.35 to 2.36.
276 L<Storable> has been upgraded from version 2.42 to 2.43.
280 L<Sys::Hostname> has been upgraded from version 1.17 to 1.18.
284 L<Sys::Syslog> has been upgraded from version 0.32 to 0.33.
288 L<Term::ReadLine> has been upgraded from version 1.12 to 1.13.
292 L<Test::Harness> has been upgraded from version 3.26 to 3.28
294 Memory usage is dramatically reduced. t/harness now uses about 10% of the
295 memory used by 3.26 and earlier.
297 C<PERL5LIB> is always propagated to a test's C<@INC>, even under C<-T>.
301 L<threads> has been upgraded from version 1.86 to 1.87.
305 L<threads::shared> has been upgraded from version 1.43 to 1.44.
309 L<Tie::File> has been upgraded from version 0.99 to 1.00.
313 L<Time::Piece> has been upgraded from version 1.20_01 to 1.2002.
317 L<Unicode::Collate> has been upgraded from version 0.97 to 0.98.
321 L<Unicode::UCD> has been upgraded from version 0.51 to 0.52.
323 A function, L<Unicode::UCD/search_invlist()> is now available to do
324 search an inversion list or map for a code point.
330 =head2 Changes to Existing Documentation
338 C<goto EXPR> is now documented to handle an expression that evalutes to a
339 code reference as if it was C<goto &$coderef>. This behavior is at least ten
344 C<eval EXPR> now has caveats about expanding floating point numbers in some
349 Noted that C<chop> and C<chomp> can reset the hash iterator
353 Improved C<fileno> example
357 =head3 L<perlexperiment>
363 C<\s> matching C<\cK> is marked experimental
367 ithreads were accepted in 5.8.0
371 Long doubles are not experimental
381 Update to mention fc(), \F
391 There is now a L<JavaScript|perltrap/JavaScript Traps> section.
397 The following additions or changes have been made to diagnostic output,
398 including warnings and fatal error messages. For the complete list of
399 diagnostic messages, see L<perldiag>.
407 L<A sequence of multiple spaces in a charnames alias definition is deprecated|perldiag/"A sequence of multiple spaces in a charnames alias definition is deprecated">
409 L<Trailing white-space in a charnames alias definition is deprecated|perldiag/"Trailing white-space in a charnames alias definition is deprecated">
411 These two deprecation warnings involving C<\N{...}> were incorrectly
412 implemented. They did not warn by default (now they do) and could not be
413 made fatal via C<< use warnings FATAL => 'deprecated' >> (now they can).
417 =head1 Utility Changes
419 =head3 F<bisect.pl> enhancements
421 The git bisection tool F<Porting/bisect.pl> has had many enhancements.
427 Can optionally run the test case with a timeout.
431 Can now run in-place in a clean git checkout.
435 Can run the test case under C<valgrind>.
439 Can apply user supplied patches and fixes to the source checkout before
444 Now has fixups to enable building several more historical ranges of bleadperl,
445 which can be useful for pinpointing the origins of bugs or behaviour changes.
449 It is provided as part of the source distribution but not installed because
450 it is not self-contained as it relies on being run from within a git
451 checkout. Note also that it makes no attempt to fix tests, correct runtime
452 bugs or make something useful to install - its purpose is to make minimal
453 changes to get any historical revision of interest to build and run as close
454 as possible to "as-was", and thereby make C<git bisect> easy to use.
456 =head1 Platform Support
458 =head2 Discontinued Platforms
464 DG/UX was a Unix sold by Data General. The last release was in April 2001.
465 It only runs on Data General's own hardware.
469 =head2 Platform-Specific Notes
473 =item Mixed-endian platforms
475 The code supporting C<pack> and C<unpack> operations on mixed endian
476 platforms has been removed. We believe that Perl has long been unable to
477 build on mixed endian architectures (such as PDP-11s), so we don't think
478 that this change will affect any platforms which are able to build v5.18.0.
482 The BUILD_STATIC and ALL_STATIC makefile options for linking some or (nearly)
483 all extensions statically (into perl519.dll, and into a separate
484 perl-static.exe too) were broken for MinGW builds. This has now been fixed.
486 The ALL_STATIC option has also been improved to include the Encode and Win32
487 extensions (for both VC++ and MinGW builds).
491 =head1 Internal Changes
497 Perl's new copy-on-write mechanism (which is now enabled by default),
498 allows any C<SvPOK> scalar to be automatically upgraded to a copy-on-write
499 scalar when copied. A reference count on the string buffer is stored in
500 the string buffer itself.
504 $ perl -MDevel::Peek -e'$a="abc"; $b = $a; Dump $a; Dump $b'
505 SV = PV(0x260cd80) at 0x2620ad8
507 FLAGS = (POK,IsCOW,pPOK)
508 PV = 0x2619bc0 "abc"\0
512 SV = PV(0x260ce30) at 0x2620b20
514 FLAGS = (POK,IsCOW,pPOK)
515 PV = 0x2619bc0 "abc"\0
520 Note that both scalars share the same PV buffer and have a COW_REFCNT
523 This means that XS code which wishes to modify the C<SvPVX()> buffer of an
524 SV should call C<SvPV_force()> or similar first, to ensure a valid (and
525 unshared) buffer, and to call C<SvSETMAGIC()> afterwards. This in fact has
526 always been the case (for example hash keys were already copy-on-write);
527 this change just spreads the COW behaviour to a wider variety of SVs.
529 One important difference is that before 5.18.0, shared hash-key scalars
530 used to have the C<SvREADONLY> flag set; this is no longer the case.
532 This new behaviour can still be disabled by running F<Configure> with
533 B<-Accflags=-DPERL_NO_COW>. This option will probably be removed in Perl
538 C<PL_sawampersand> is now a constant. The switch this variable provided
539 (to enable/disable the pre-match copy depending on whether C<$&> had been
540 seen) has been removed and replaced with copy-on-write, eliminating a few
543 The previous behaviour can still be enabled by running F<Configure> with
544 B<-Accflags=-DPERL_SAWAMPERSAND>.
548 The functions C<my_swap>, C<my_htonl> and C<my_ntohl> have been removed.
549 It is unclear why these functions were ever marked as I<A>, part of the
550 API. XS code can't call them directly, as it can't rely on them being
551 compiled. Unsurprisingly, no code on CPAN references them.
555 The signature of the C<Perl_re_intuit_start()> regex function has changed;
556 the function pointer C<intuit> in the regex engine plugin structure
557 has also changed accordingly. A new parameter, C<strbeg> has been added;
558 this has the same meaning as the same-named parameter in
559 C<Perl_regexec_flags>. Previously intuit would try to guess the start of
560 the string from the passed SV (if any), and would sometimes get it wrong
561 (e.g. with an overloaded SV).
565 XS code may use various macros to change the case of a character or code
566 point (for example C<toLOWER_utf8()>). Only a couple of these were
567 documented until now;
568 and now they should be used in preference to calling the underlying
569 functions. See L<perlapi/Character case changing>.
573 The code dealt rather inconsistently with uids and gids. Some
574 places assumed that they could be safely stored in UVs, others
575 in IVs, others in ints. Four new macros are introduced:
576 SvUID(), sv_setuid(), SvGID(), and sv_setgid()
580 =head1 Selected Bug Fixes
586 The OP allocation code now returns correctly aligned memory in all cases
587 for C<struct pmop>. Previously it could return memory only aligned to a
588 4-byte boundary, which is not correct for an ithreads build with 64 bit IVs
589 on some 32 bit platforms. Notably, this caused the build to fail completely
590 on sparc GNU/Linux. [RT #118055]
594 The debugger's C<man> command been fixed. It was broken in the v5.18.0
595 release. The C<man> command is aliased to the names C<doc> and C<perldoc> -
600 C<@_> is now correctly visible in the debugger, fixing a regression
601 introduced in v5.18.0's debugger. [RT #118169]
605 Evaluating large hashes in scalar context is now much faster, as the number
606 of used chains in the hash is now cached for larger hashes. Smaller hashes
607 continue not to store it and calculate it when needed, as this saves one IV.
608 That would be 1 IV overhead for every object built from a hash. [RT #114576]
612 Fixed a small number of regexp constructions that could either fail to
613 match or crash perl when the string being matched against was
614 allocated above the 2GB line on 32-bit systems. [RT #118175]
618 Perl v5.16 inadvertently introduced a bug whereby calls to XSUBs that were
619 not visible at compile time were treated as lvalues and could be assigned
620 to, even when the subroutine was not an lvalue sub. This has been fixed.
625 In Perl v5.18.0 dualvars that had an empty string for the string part but a
626 non-zero number for the number part starting being treated as true. In
627 previous versions they were treated as false, the string representation
628 taking precedeence. The old behaviour has been restored. [RT #118159]
632 Since Perl v5.12, inlining of constants that override built-in keywords of
633 the same name had countermanded C<use subs>, causing subsequent mentions of
634 the constant to use the built-in keyword instead. This has been fixed.
638 Lexical constants (C<my sub a() { 42 }>) no longer crash when inlined.
642 Parameter prototypes attached to lexical subroutines are now respected when
643 compiling sub calls without parentheses. Previously, the prototypes were
644 honoured only for calls I<with> parentheses. [RT #116735]
648 Syntax errors in lexical subroutines in combination with calls to the same
649 subroutines no longer cause crashes at compile time.
653 The warning produced by C<-l $handle> now applies to IO refs and globs, not
654 just to glob refs. That warning is also now UTF8-clean. [RT #117595]
658 Various memory leaks involving the parsing of the C<(?[...])> regular
659 expression construct have been fixed.
663 C<(?[...])> now allows interpolation of precompiled patterns consisting of
664 C<(?[...])> with bracketed character classes inside (C<$pat =
665 S<qr/(?[ [a] ])/;> S</(?[ $pat ])/>>). Formerly, the brackets would
666 confuse the regular expression parser.
670 The "Quantifier unexpected on zero-length expression" warning message could
671 appear twice starting in Perl v5.10 for a regular expression also
672 containing alternations (e.g., "a|b") triggering the trie optimisation.
676 C<delete local $ENV{nonexistent_env_var}> no longer leaks memory.
680 C<sort> and C<require> followed by a keyword prefixed with C<CORE::> now
681 treat it as a keyword, and not as a subroutine or module name. [RT #24482]
685 Through certain conundrums, it is possible to cause the current package to
686 be freed. Certain operators (C<bless>, C<reset>, C<open>, C<eval>) could
687 not cope and would crash. They have been made more resilient. [RT #117941]
691 Aliasing filehandles through glob-to-glob assignment would not update
692 internal method caches properly if a package of the same name as the
693 filehandle existed, resulting in filehandle method calls going to the
694 package instead. This has been fixed.
698 C<./Configure -de -Dusevendorprefix> didn't default [RT #64126]
702 The C<Statement unlikely to be reached> warning was listed in
703 L<perldiag> as an C<exec>-category warning, but was enabled and disabled
704 by the C<syntax> category. On the other hand, the C<exec> category
705 controlled its fatal-ness. It is now entirely handled by the C<exec>
710 The "Replacement list is longer that search list" warning for C<tr///> and
711 C<y///> no longer occurs in the presence of the C</c> flag. [RT #118047]
715 Perl v5.18 inadvertently introduced a bug whereby interpolating mixed up-
716 and down-graded UTF-8 strings in a regex could result in malformed UTF-8
717 in the pattern: specifically if a downgraded character in the range
718 C<\x80..\xff> followed a UTF-8 string, e.g.
720 utf8::upgrade( my $u = "\x{e5}");
721 utf8::downgrade(my $d = "\x{e5}");
728 Stringification of NVs are not cached so that the lexical locale controls
729 stringification of the decimal point [perl #108378] [perl #115800]
733 =head1 Acknowledgements
735 Perl 5.19.1 represents approximately 4 weeks of development since Perl 5.19.0
736 and contains approximately 26,000 lines of changes across 680 files from 37
739 Perl continues to flourish into its third decade thanks to a vibrant community
740 of users and developers. The following people are known to have contributed the
741 improvements that became Perl 5.19.1:
743 Alexandr Ciornii, Brian Fraser, Chris 'BinGOs' Williams, Craig A. Berry,
744 Dagfinn Ilmari Mannsåker, Daniel Dragan, David Golden, David Mitchell, David
745 Steinbrunner, Dominic Hargreaves, Eric Brine, Father Chrysostomos, H.Merijn
746 Brand, Heiko Eissfeldt, James E Keenan, Jerry D. Hedden, Kang-min Liu, Karl
747 Williamson, Leon Timmermans, Lukas Mai, Marcel Grünauer, Mark Jason Dominus,
748 Max Maischein, Mike Doherty, Nicholas Clark, Paul Green, Peter Martini, Petr
749 Písař, Ricardo Signes, Shirakata Kentaro, Shlomi Fish, Steffen Müller, Steve
750 Hay, Sullivan Beck, Tony Cook, Yves Orton, Zsbán Ambrus.
752 The list above is almost certainly incomplete as it is automatically generated
753 from version control history. In particular, it does not include the names of
754 the (very much appreciated) contributors who reported issues to the Perl bug
757 Many of the changes included in this version originated in the CPAN modules
758 included in Perl's core. We're grateful to the entire CPAN community for
759 helping Perl to flourish.
761 For a more complete list of all of Perl's historical contributors, please see
762 the F<AUTHORS> file in the Perl source distribution.
764 =head1 Reporting Bugs
766 If you find what you think is a bug, you might check the articles recently
767 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
768 http://rt.perl.org/perlbug/ . There may also be information at
769 http://www.perl.org/ , the Perl Home Page.
771 If you believe you have an unreported bug, please run the L<perlbug> program
772 included with your release. Be sure to trim your bug down to a tiny but
773 sufficient test case. Your bug report, along with the output of C<perl -V>,
774 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
776 If the bug you are reporting has security implications, which make it
777 inappropriate to send to a publicly archived mailing list, then please send it
778 to perl5-security-report@perl.org. This points to a closed subscription
779 unarchived mailing list, which includes all the core committers, who will be
780 able to help assess the impact of issues, figure out a resolution, and help
781 co-ordinate the release of patches to mitigate or fix the problem across all
782 platforms on which Perl is supported. Please only use this address for
783 security issues in the Perl core, not for modules independently distributed on
788 The F<Changes> file for an explanation of how to view exhaustive details on
791 The F<INSTALL> file for how to build Perl.
793 The F<README> file for general stuff.
795 The F<Artistic> and F<Copying> files for copyright information.