5 [ this is a template for a new perldelta file. Any text flagged as XXX needs
6 to be processed before release. ]
8 perldelta - what is new for perl v5.25.9
12 This document describes differences between the 5.25.8 release and the 5.25.9
15 If you are upgrading from an earlier release such as 5.25.7, first read
16 L<perl5258delta>, which describes differences between 5.25.7 and 5.25.8.
20 XXX Any important notices here
22 =head1 Core Enhancements
24 XXX New core language features go here. Summarize user-visible core language
25 enhancements. Particularly prominent performance optimisations could go
26 here, but most should go in the L</Performance Enhancements> section.
28 =head2 New regular expression modifier C</xx>
30 Specifying two C<x> characters to modify a regular expression pattern
31 does everything that a single one does, but additionally TAB and SPACE
32 characters within a bracketed character class are generally ignored and
33 can be added to improve readability, like
34 S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
35 L<perlre/E<sol>x and E<sol>xx>.
39 XXX Any security-related notices go here. In particular, any security
40 vulnerabilities closed should be noted here rather than in the
41 L</Selected Bug Fixes> section.
43 [ List each security issue as a =head2 entry ]
45 =head1 Incompatible Changes
47 XXX For a release on a stable branch, this section aspires to be:
49 There are no changes intentionally incompatible with 5.XXX.XXX
50 If any exist, they are bugs, and we request that you submit a
51 report. See L</Reporting Bugs> below.
53 [ List each incompatible change as a =head2 entry ]
57 =head2 String delimiters that aren't stand-alone graphemes are now
60 In order for Perl to eventually allow string delimiters to be Unicode
61 grapheme clusters (which look like a single character, but may be
62 a sequence of several ones), we have to stop allowing a single char
63 delimiter that isn't a grapheme by itself. These are unlikely to exist
64 in actual code, as they would typically display as attached to the
65 character in front of them.
67 =head2 Module removals
69 XXX Remove this section if inapplicable.
71 The following modules will be removed from the core distribution in a
72 future release, and will at that time need to be installed from CPAN.
73 Distributions on CPAN which require these modules will need to list them as
76 The core versions of these modules will now issue C<"deprecated">-category
77 warnings to alert you to this fact. To silence these deprecation warnings,
78 install the modules in question from CPAN.
80 Note that these are (with rare exceptions) fine modules that you are encouraged
81 to continue to use. Their disinclusion from core primarily hinges on their
82 necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
83 not usually on concerns over their design.
89 XXX Note that deprecated modules should be listed here even if they are listed
90 as an updated module in the L</Modules and Pragmata> section.
94 [ List each other deprecation as a =head2 entry ]
96 =head1 Performance Enhancements
98 XXX Changes which enhance performance without changing behaviour go here.
99 There may well be none in a stable release.
101 [ List each enhancement as a =item entry ]
107 A hash in boolean context is now sometimes faster, e.g.
111 This was already special-cased, but some cases were missed, and even the
112 ones which weren't have been improved.
116 =head1 Modules and Pragmata
118 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
119 go here. If Module::CoreList is updated, generate an initial draft of the
120 following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
121 for important changes should then be added by hand. In an ideal world,
122 dual-life modules would have a F<Changes> file that could be cribbed.
124 [ Within each section, list entries as a =item entry ]
126 =head2 New Modules and Pragmata
136 =head2 Updated Modules and Pragmata
142 L<XXX> has been upgraded from version A.xx to B.yy.
146 L<re> has been upgraded from version 0.33 to 0.34;
148 This adds support for the new L<C</xx>|perlre/E<sol>x and E<sol>xx>
149 regular expression pattern modifier, and a change to the L<S<C<use re
150 'strict'>>|re/'strict' mode> experimental feature. When S<C<re
151 'strict'>> is enabled, a warning now will be generated for all
152 unescaped uses of the two characters C<}> and C<]> in regular
153 expression patterns (outside bracketed character classes) that are taken
154 literally. This brings them more in line with the C<)> character which
155 is always a metacharacter unless escaped. Being a metacharacter only
156 sometimes, depending on action at a distance, can lead to silently
157 having the pattern mean something quite different than was intended,
158 which the S<C<re 'strict'>> mode is intended to minimize.
162 L<B::Xref> has been upgraded from version 1.05 to 1.06.
166 L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.070.
170 L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.070.
174 L<DB_File> has been upgraded from version 1.838 to 1.840.
178 L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
182 L<diagnostics> has been upgraded from version 1.35 to 1.36.
186 L<DynaLoader> has been upgraded from version 1.40 to 1.41.
190 L<Errno> has been upgraded from version 1.27 to 1.28.
194 L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
198 L<I18N::LangTags> has been upgraded from version 0.41 to 0.42.
202 L<lib> has been upgraded from version 0.63 to 0.64.
206 L<Module::CoreList> has been upgraded from version 5.20161220 to 5.20170120.
210 L<OS2::Process> has been upgraded from version 1.11 to 1.12.
214 L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
218 L<Storable> has been upgraded from version 2.59 to 2.61.
222 L<Symbol> has been upgraded from version 1.07 to 1.08.
226 L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
230 L<Test> has been upgraded from version 1.29 to 1.30.
234 L<threads::shared> has been upgraded from version 1.52 to 1.53.
238 L<Unicode::UCD> has been upgraded from version 0.67 to 0.68.
242 L<VMS::DCLsym> has been upgraded from version 1.07 to 1.08.
246 L<XSLoader> has been upgraded from version 0.24 to 0.26.
250 L<CPAN> has been upgraded from version 2.14_01 to 2.16.
254 =head2 Removed Modules and Pragmata
266 XXX Changes to files in F<pod/> go here. Consider grouping entries by
267 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
269 =head2 New Documentation
271 XXX Changes which create B<new> files in F<pod/> go here.
275 XXX Description of the purpose of the new file here
277 =head2 Changes to Existing Documentation
279 XXX Changes which significantly change existing files in F<pod/> go here.
280 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
289 XXX Description of the change here
295 The following additions or changes have been made to diagnostic output,
296 including warnings and fatal error messages. For the complete list of
297 diagnostic messages, see L<perldiag>.
299 XXX New or changed warnings emitted by the core's C<C> code go here. Also
300 include any changes in L<perldiag> that reconcile it to the C<C> code.
302 =head2 New Diagnostics
304 XXX Newly added diagnostic messages go under here, separated into New Errors
313 XXX L<message|perldiag/"message">
323 XXX L<message|perldiag/"message">
327 =head2 Changes to Existing Diagnostics
329 As of Perl 5.25.9, all new deprecations will come with a version in
330 which the feature will disappear. And with a few exceptions, most
331 existing deprecations will state when they'll disappear. As such, most
332 deprecation messages have changed.
338 Attribute "locked" is deprecated, and will disappear in Perl 5.28
342 Attribute "unique" is deprecated, and will disappear in Perl 5.28
346 "\c%c" is more clearly written simply as "%s". This will be a fatal error
351 Constants from lexical variables potentially modified elsewhere are
352 deprecated. This will not be allowed in Perl 5.32
356 Deprecated use of my() in false conditional. This will be a fatal error
361 dump() better written as CORE::dump(). dump() will no longer be available
366 ${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
370 File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
375 %s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
379 $* is no longer supported. Its use will be fatal in Perl 5.30
383 $* is no longer supported. Its use will be fatal in Perl 5.30
387 Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
391 Opening filehandle %s also as a directory. This will be a fatal
396 Setting $/ to a reference to %s as a form of slurp is deprecated,
397 treating as undef. This will be fatal in Perl 5.28
401 Unescaped left brace in regex is deprecated here (and will be fatal
402 in Perl 5.30), passed through in regex; marked by S<<-- HERE> in m/%s/
406 Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
410 Use of bare << to mean <<"" is deprecated. Its use will be fatal in Perl 5.28
414 Use of code point 0x%s is deprecated; the permissible max is 0x%s.
415 This will be fatal in Perl 5.28
419 Use of comma-less variable list is deprecated. Its use will be fatal
424 Use of inherited AUTOLOAD for non-method %s() is deprecated. This
425 will be fatal in Perl 5.28
429 Use of strings with code points over 0xFF as arguments to %s operator
430 is deprecated. This will be a fatal error in Perl 5.28
434 =head1 Utility Changes
436 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
437 Most of these are built within the directory F<utils>.
439 [ List utility changes as a =head2 entry for each utility and =item
440 entries for each change
441 Use L<XXX> with program names to get proper documentation linking. ]
453 =head1 Configuration and Compilation
455 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
456 go here. Any other changes to the Perl build process should be listed here.
457 However, any platform-specific changes should be listed in the
458 L</Platform Support> section, instead.
460 [ List changes as a =item entry ].
466 The C<dtrace> build process has further changes:
472 If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
473 built within a FreeBSD jail.
477 On systems that build a dtrace object file (FreeBSD, Solaris and
478 SystemTap's dtrace emulation), copy the input objects to a separate
479 directory and process them there, and use those objects in the link,
480 since C<dtrace -G> also modifies these objects.
484 Add libelf to the build on FreeBSD 10.x, since dtrace adds references
489 Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
490 default build on Solaris generates probes from the unused inline
491 functions, while they don't on FreeBSD, which causes C<dtrace -G> to
500 You can now disable perl's use of the PERL_HASH_SEED and
501 PERL_PERTURB_KEYS environment variables by configureing perl with
502 C<-Accflags=NO_PERL_HASH_ENV>.
506 You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment
507 variable by configuring perl with
508 C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
514 XXX Any significant changes to the testing of a freshly built perl should be
515 listed here. Changes which create B<new> files in F<t/> go here as do any
516 large changes to the testing harness (e.g. when parallel testing was added).
517 Changes to existing files in F<t/> aren't worth summarizing, although the bugs
518 that they represent may be covered elsewhere.
520 [ List each test improvement as a =item entry ]
530 =head1 Platform Support
532 XXX Any changes to platform support should be listed in the sections below.
534 [ Within the sections, list each platform as a =item entry with specific
535 changes as paragraphs below it. ]
539 XXX List any platforms that this version of perl compiles on, that previous
540 versions did not. These will either be enabled by new files in the F<hints/>
541 directories, or new subdirectories and F<README> files at the top level of the
546 =item XXX-some-platform
552 =head2 Discontinued Platforms
554 XXX List any platforms that this version of perl no longer compiles on.
558 =item XXX-some-platform
564 =head2 Platform-Specific Notes
566 XXX List any changes for specific platforms. This could include configuration
567 and compilation changes or changes in portability/compatibility. However,
568 changes within modules for platforms should generally be listed in the
569 L</Modules and Pragmata> section.
573 =item XXX-some-platform
579 =head1 Internal Changes
581 XXX Changes which affect the interface available to C<XS> code go here. Other
582 significant internal changes for future core maintainers should be noted as
585 [ List each change as a =item entry ]
591 New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
592 been added, each with the
593 suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
594 parameter, giving an upper limit of how far into the string it is safe
595 to read. Using the old versions could cause attempts to read beyond the
596 end of the input buffer if the UTF-8 is not well-formed, and ther use
597 now raises a deprecation warning. Details are at
598 L<perlapi/Character classification>.
602 Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
603 deprecation warning since Perl v5.18. They now die.
604 Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
608 Calling the functions C<utf8n_to_uvchr> and its derivatives, while
609 passing a string length of 0 is now asserted against in DEBUGGING
610 builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If
611 you have nothing to decode, you shouldn't call the decode function.
615 The functions C<utf8n_to_uvchr> and its derivatives now return the
616 Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong
617 malformation, and that malformation is allowed by the input parameters.
618 This malformation is where the UTF-8 looks valid syntactically, but
619 there is a shorter sequence that yields the same code point. This has
620 been forbidden since Unicode version 3.1.
624 The functions C<utf8n_to_uvchr> and its derivatives now accept an input
625 flag to allow the overflow malformation. This malformation is when the
626 UTF-8 may be syntactically valid, but the code point it represents is
627 not capable of being represented in the word length on the platform.
628 What "allowed" means in this case is that the function doesn't return an
629 error, and advances the parse pointer to beyond the UTF-8 in question,
630 but it returns the Unicode REPLACEMENT CHARACTER as the value of the
631 code point (since the real value is not representable).
635 =head1 Selected Bug Fixes
637 XXX Important bug fixes in the core language are summarized here. Bug fixes in
638 files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
640 [ List each fix as a =item entry ]
646 Under C<use utf8>, the entire Perl program is now checked that the UTF-8
647 is wellformed. This resolves [perl #126310].
651 The range operator C<..> on strings now handles its arguments correctly when in
652 the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
653 feature. The previous behaviour was sufficiently unexpected that we believe no
654 correct program could have made use of it.
658 The S<split> operator did not ensure enough space was allocated for
659 its return value in scalar context. It could then write a single
660 pointer immediately beyond the end of the memory block allocated for
661 the stack. [perl #130262]
665 Using a large code point with the C<W> pack template character with
666 the current output position aligned at just the right point could
667 cause a write a single zero byte immediately beyond the end of an
668 allocated buffer. [perl #129149]
672 =head1 Known Problems
674 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
675 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
676 platform specific bugs also go here.
678 [ List each fix as a =item entry ]
688 =head1 Errata From Previous Releases
694 XXX Add anything here that we forgot to add, or were mistaken about, in
695 the perldelta of a previous release.
701 XXX If any significant core contributor has died, we've added a short obituary
704 =head1 Acknowledgements
706 XXX Generate this with:
708 perl Porting/acknowledgements.pl v5.25.5..HEAD
710 =head1 Reporting Bugs
712 If you find what you think is a bug, you might check the perl bug database
713 at L<https://rt.perl.org/> . There may also be information at
714 L<http://www.perl.org/> , the Perl Home Page.
716 If you believe you have an unreported bug, please run the L<perlbug> program
717 included with your release. Be sure to trim your bug down to a tiny but
718 sufficient test case. Your bug report, along with the output of C<perl -V>,
719 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
721 If the bug you are reporting has security implications which make it
722 inappropriate to send to a publicly archived mailing list, then see
723 L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
724 for details of how to report the issue.
728 The F<Changes> file for an explanation of how to view exhaustive details on
731 The F<INSTALL> file for how to build Perl.
733 The F<README> file for general stuff.
735 The F<Artistic> and F<Copying> files for copyright information.