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 v5.21.5
12 This document describes differences between the 5.21.4 release and the 5.21.5
15 If you are upgrading from an earlier release such as 5.21.3, first read
16 L<perl5214delta>, which describes differences between 5.21.3 and 5.21.4.
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 [ List each enhancement as a =head2 entry ]
30 =head2 Perl now supports POSIX 2008 locale currency additions.
32 On platforms that are able to handle POSIX.1-2008, the
34 L<C<POSIX::localeconv()>|perllocale/The localeconv function>
35 includes the international currency fields added by that version of the
36 POSIX standard. These are
38 C<int_n_sep_by_space>,
41 C<int_p_sep_by_space>,
47 =head2 Perl is now compiled with -fstack-protector-strong if available
49 Perl has been compiled with the anti-stack-smashing option
50 C<-fstack-protector> since 5.10.1. Now Perl uses the newer variant
51 called C<-fstack-protector-strong>, if available. (This was added
54 [ List each security issue as a =head2 entry ]
56 =head1 Incompatible Changes
58 XXX For a release on a stable branch, this section aspires to be:
60 There are no changes intentionally incompatible with 5.XXX.XXX
61 If any exist, they are bugs, and we request that you submit a
62 report. See L</Reporting Bugs> below.
64 [ List each incompatible change as a =head2 entry ]
68 XXX Any deprecated features, syntax, modules etc. should be listed here.
70 =head2 Module removals
72 XXX Remove this section if inapplicable.
74 The following modules will be removed from the core distribution in a
75 future release, and will at that time need to be installed from CPAN.
76 Distributions on CPAN which require these modules will need to list them as
79 The core versions of these modules will now issue C<"deprecated">-category
80 warnings to alert you to this fact. To silence these deprecation warnings,
81 install the modules in question from CPAN.
83 Note that these are (with rare exceptions) fine modules that you are encouraged
84 to continue to use. Their disinclusion from core primarily hinges on their
85 necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
86 not usually on concerns over their design.
92 XXX Note that deprecated modules should be listed here even if they are listed
93 as an updated module in the L</Modules and Pragmata> section.
97 =head2 Use of multiple /x regexp modifiers
99 It is now deprecated to say something like any of the following:
105 That is, now C<x> should only occur once in any string of contiguous
106 regular expression pattern modifiers. We do not believe there are any
107 occurrences of this in all of CPAN. This is in preparation for a future
108 Perl release having C</xx> mean to allow white-space for readability in
109 bracketed character classes (those enclosed in square brackets:
112 =head1 Performance Enhancements
114 XXX Changes which enhance performance without changing behaviour go here.
115 There may well be none in a stable release.
117 [ List each enhancement as a =item entry ]
123 C<length> is up to 20% faster for non-magical/non-tied scalars containing a
124 string if it is a non-utf8 string or if C<use bytes;> is in scope.
128 Non-magical/non-tied scalars that contain only a floating point value and are
129 on most Perl builds with 64 bit integers now use 8-32 less bytes of memory
134 =head1 Modules and Pragmata
136 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
137 go here. If Module::CoreList is updated, generate an initial draft of the
138 following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
139 for important changes should then be added by hand. In an ideal world,
140 dual-life modules would have a F<Changes> file that could be cribbed.
142 [ Within each section, list entries as a =item entry ]
144 =head2 New Modules and Pragmata
154 =head2 Updated Modules and Pragmata
160 L<attributes> has been upgraded from version 0.23 to 0.24.
162 Avoid reading beyond the end of a buffer. [perl #122629]
166 L<DynaLoader> has been upgraded from version 1.26 to 1.27.
168 Remove dl_nonlazy global if unused in Dynaloader. [perl #122926]
172 L<Module::CoreList> has been upgraded from version 5.20140920 to 5.20141020.
174 Updated to cover the latest releases of Perl.
178 L<XSLoader> has been upgraded from version 0.17 to 0.18.
180 Allow XSLoader to load modules from a different namespace.
185 =head2 Removed Modules and Pragmata
197 XXX Changes to files in F<pod/> go here. Consider grouping entries by
198 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
200 =head2 New Documentation
202 XXX Changes which create B<new> files in F<pod/> go here.
206 XXX Description of the purpose of the new file here
208 =head2 Changes to Existing Documentation
210 XXX Changes which significantly change existing files in F<pod/> go here.
211 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
220 Clarifications have been added to L<perlrecharclass/Character Ranges>
221 to the effect that Perl guarantees that C<[A-Z]>, C<[a-z]>, C<[0-9]> and
222 any subranges thereof in regular expression bracketed character classes
223 are guaranteed to match exactly what a naive English speaker would
224 expect them to match, even on platforms (such as EBCDIC) where special
225 handling is required to accomplish this.
231 The following additions or changes have been made to diagnostic output,
232 including warnings and fatal error messages. For the complete list of
233 diagnostic messages, see L<perldiag>.
235 XXX New or changed warnings emitted by the core's C<C> code go here. Also
236 include any changes in L<perldiag> that reconcile it to the C<C> code.
238 =head2 New Diagnostics
240 XXX Newly added diagnostic messages go under here, separated into New Errors
249 XXX L<message|perldiag/"message">
259 XXX L<message|perldiag/"message">
263 =head2 Changes to Existing Diagnostics
265 XXX Changes (i.e. rewording) of diagnostic messages go here
271 XXX Describe change here
275 =head1 Utility Changes
277 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
278 Most of these are built within the directory F<utils>.
280 [ List utility changes as a =head2 entry for each utility and =item
281 entries for each change
282 Use L<XXX> with program names to get proper documentation linking. ]
294 =head1 Configuration and Compilation
296 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
297 go here. Any other changes to the Perl build process should be listed here.
298 However, any platform-specific changes should be listed in the
299 L</Platform Support> section, instead.
301 [ List changes as a =item entry ].
313 XXX Any significant changes to the testing of a freshly built perl should be
314 listed here. Changes which create B<new> files in F<t/> go here as do any
315 large changes to the testing harness (e.g. when parallel testing was added).
316 Changes to existing files in F<t/> aren't worth summarizing, although the bugs
317 that they represent may be covered elsewhere.
319 [ List each test improvement as a =item entry ]
329 =head1 Platform Support
331 XXX Any changes to platform support should be listed in the sections below.
333 [ Within the sections, list each platform as a =item entry with specific
334 changes as paragraphs below it. ]
338 XXX List any platforms that this version of perl compiles on, that previous
339 versions did not. These will either be enabled by new files in the F<hints/>
340 directories, or new subdirectories and F<README> files at the top level of the
345 =item XXX-some-platform
351 =head2 Discontinued Platforms
353 XXX List any platforms that this version of perl no longer compiles on.
357 =item XXX-some-platform
363 =head2 Platform-Specific Notes
365 XXX List any changes for specific platforms. This could include configuration
366 and compilation changes or changes in portability/compatibility. However,
367 changes within modules for platforms should generally be listed in the
368 L</Modules and Pragmata> section.
374 Special handling is required on EBCDIC platforms to get C<qr/[i-j]/> to
375 match only C<"i"> and C<"j">, since there are 7 characters between the
376 code points for C<"i"> and C<"j">. This special handling had only been
377 invoked when both ends of the range are literals. Now it is also
378 invoked if any of the C<\N{...}> forms for specifying a character by
379 name or Unicode code point is used instead of a literal. See
380 L<perlrecharclass/Character Ranges>.
384 =head1 Internal Changes
386 XXX Changes which affect the interface available to C<XS> code go here. Other
387 significant internal changes for future core maintainers should be noted as
390 [ List each change as a =item entry ]
396 SVs of type SVt_NV are now bodyless when a build configure and platform allow
397 it, specifically C<sizeof(NV) <= sizeof(IV)>. The bodyless trick is the same one
398 as for IVs since 5.9.2, but for NVs, unlike IVs, is not guarenteed on all
399 platforms and build configurations.
403 The C<$DB::single>, C<$DB::signal> and C<$DB::trace> now have set and
404 get magic that stores their values as IVs and those IVs are used when
405 testing their values in C<pp_dbstate>. This prevents perl from
406 recursing infinity if an overloaded object is assigned to any of those
407 variables. [perl #122445]
411 C<Perl_tmps_grow> which is marked as public API but undocumented has been
412 removed from public API. If you use C<EXTEND_MORTAL> macro in your XS code to
413 preextend the mortal stack, you are unaffected by this change.
417 =head1 Selected Bug Fixes
419 XXX Important bug fixes in the core language are summarized here. Bug fixes in
420 files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
422 [ List each fix as a =item entry ]
432 =head1 Known Problems
434 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
435 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
436 platform specific bugs also go here.
438 [ List each fix as a =item entry ]
448 =head1 Errata From Previous Releases
454 XXX Add anything here that we forgot to add, or were mistaken about, in
455 the perldelta of a previous release.
461 XXX If any significant core contributor has died, we've added a short obituary
464 =head1 Acknowledgements
466 XXX Generate this with:
468 perl Porting/acknowledgements.pl v5.21.4..HEAD
470 =head1 Reporting Bugs
472 If you find what you think is a bug, you might check the articles recently
473 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
474 https://rt.perl.org/ . There may also be information at
475 http://www.perl.org/ , the Perl Home Page.
477 If you believe you have an unreported bug, please run the L<perlbug> program
478 included with your release. Be sure to trim your bug down to a tiny but
479 sufficient test case. Your bug report, along with the output of C<perl -V>,
480 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
482 If the bug you are reporting has security implications, which make it
483 inappropriate to send to a publicly archived mailing list, then please send it
484 to perl5-security-report@perl.org. This points to a closed subscription
485 unarchived mailing list, which includes all the core committers, who will be
486 able to help assess the impact of issues, figure out a resolution, and help
487 co-ordinate the release of patches to mitigate or fix the problem across all
488 platforms on which Perl is supported. Please only use this address for
489 security issues in the Perl core, not for modules independently distributed on
494 The F<Changes> file for an explanation of how to view exhaustive details on
497 The F<INSTALL> file for how to build Perl.
499 The F<README> file for general stuff.
501 The F<Artistic> and F<Copying> files for copyright information.