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 v5.27.1
12 This document describes differences between the 5.27.0 release and the 5.27.1
15 If you are upgrading from an earlier release such as 5.26.0, first read
16 L<perl5270delta>, which describes differences between 5.26.0 and 5.27.0.
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 ]
32 XXX Any security-related notices go here. In particular, any security
33 vulnerabilities closed should be noted here rather than in the
34 L</Selected Bug Fixes> section.
36 [ List each security issue as a =head2 entry ]
38 =head1 Incompatible Changes
40 XXX For a release on a stable branch, this section aspires to be:
42 There are no changes intentionally incompatible with 5.XXX.XXX
43 If any exist, they are bugs, and we request that you submit a
44 report. See L</Reporting Bugs> below.
46 [ List each incompatible change as a =head2 entry ]
48 =head2 Comma-less variable lists in formats are no longer allowed
50 Omitting the commas between variables passed to formats is no longer
51 allowed. This has been deprecated since perl 5.000.
53 =head2 The C<:locked> and C<:unique> attributes have been removed
55 These have been no-ops and deprecated since perl 5.12 and 5.10,
58 =head2 C<\N{}> with nothing between the braces is now illegal.
60 This has been deprecated since Perl 5.24.
64 XXX Any deprecated features, syntax, modules etc. should be listed here.
66 =head2 Some uses of unescaped C<"{"> are no longer fatal
68 Perl 5.26.0 fatalized some uses of an unescaped left brace, but an
69 exception was made at the last minute, specifically crafted to be a
70 minimal change to allow GNU Autoconf to work. This code is heavily
71 depended upon, and continues to use the deprecated usage. Its use of an
72 unescaped left brace is one where we have no intention of repurposing
73 C<"{"> to be something other than itself.
75 That exception is now generalized to include various other such cases
76 where the C<"{"> will not be repurposed. This is to get real experience
77 with this more complicated change now, in case we need to issue a dot
78 release if we find other things like Autoconf that are important to work
81 Note that these uses continue to raise a deprecation message.
83 =head2 Module removals
85 XXX Remove this section if inapplicable.
87 The following modules will be removed from the core distribution in a
88 future release, and will at that time need to be installed from CPAN.
89 Distributions on CPAN which require these modules will need to list them as
92 The core versions of these modules will now issue C<"deprecated">-category
93 warnings to alert you to this fact. To silence these deprecation warnings,
94 install the modules in question from CPAN.
96 Note that these are (with rare exceptions) fine modules that you are encouraged
97 to continue to use. Their disinclusion from core primarily hinges on their
98 necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
99 not usually on concerns over their design.
105 XXX Note that deprecated modules should be listed here even if they are listed
106 as an updated module in the L</Modules and Pragmata> section.
110 [ List each other deprecation as a =head2 entry ]
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 ]
127 =head1 Modules and Pragmata
129 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
130 go here. If Module::CoreList is updated, generate an initial draft of the
131 following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
132 for important changes should then be added by hand. In an ideal world,
133 dual-life modules would have a F<Changes> file that could be cribbed.
135 [ Within each section, list entries as a =item entry ]
137 =head2 New Modules and Pragmata
147 =head2 Updated Modules and Pragmata
153 L<XXX> has been upgraded from version A.xx to B.yy.
157 =head2 Removed Modules and Pragmata
169 XXX Changes to files in F<pod/> go here. Consider grouping entries by
170 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
172 =head2 New Documentation
174 XXX Changes which create B<new> files in F<pod/> go here.
178 XXX Description of the purpose of the new file here
180 =head2 Changes to Existing Documentation
182 XXX Changes which significantly change existing files in F<pod/> go here.
183 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
192 XXX Description of the change here
198 The following additions or changes have been made to diagnostic output,
199 including warnings and fatal error messages. For the complete list of
200 diagnostic messages, see L<perldiag>.
202 XXX New or changed warnings emitted by the core's C<C> code go here. Also
203 include any changes in L<perldiag> that reconcile it to the C<C> code.
205 =head2 New Diagnostics
207 XXX Newly added diagnostic messages go under here, separated into New Errors
216 XXX L<message|perldiag/"message">
226 XXX L<message|perldiag/"message">
230 =head2 Changes to Existing Diagnostics
232 XXX Changes (i.e. rewording) of diagnostic messages go here
238 XXX Describe change here
242 =head1 Utility Changes
244 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
245 Most of these are built within the directory F<utils>.
247 [ List utility changes as a =head2 entry for each utility and =item
248 entries for each change
249 Use L<XXX> with program names to get proper documentation linking. ]
261 =head1 Configuration and Compilation
263 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
264 go here. Any other changes to the Perl build process should be listed here.
265 However, any platform-specific changes should be listed in the
266 L</Platform Support> section, instead.
268 [ List changes as a =item entry ].
280 XXX Any significant changes to the testing of a freshly built perl should be
281 listed here. Changes which create B<new> files in F<t/> go here as do any
282 large changes to the testing harness (e.g. when parallel testing was added).
283 Changes to existing files in F<t/> aren't worth summarizing, although the bugs
284 that they represent may be covered elsewhere.
286 [ List each test improvement as a =item entry ]
296 =head1 Platform Support
298 XXX Any changes to platform support should be listed in the sections below.
300 [ Within the sections, list each platform as a =item entry with specific
301 changes as paragraphs below it. ]
305 XXX List any platforms that this version of perl compiles on, that previous
306 versions did not. These will either be enabled by new files in the F<hints/>
307 directories, or new subdirectories and F<README> files at the top level of the
312 =item XXX-some-platform
318 =head2 Discontinued Platforms
320 XXX List any platforms that this version of perl no longer compiles on.
324 =item XXX-some-platform
330 =head2 Platform-Specific Notes
332 XXX List any changes for specific platforms. This could include configuration
333 and compilation changes or changes in portability/compatibility. However,
334 changes within modules for platforms should generally be listed in the
335 L</Modules and Pragmata> section.
339 =item XXX-some-platform
345 =head1 Internal Changes
347 XXX Changes which affect the interface available to C<XS> code go here. Other
348 significant internal changes for future core maintainers should be noted as
351 [ List each change as a =item entry ]
357 The C<PL_statbuf> interpreter variable has been removed.
361 The deprecated function C<to_utf8_case()>, accessible from XS code, has
366 =head1 Selected Bug Fixes
368 XXX Important bug fixes in the core language are summarized here. Bug fixes in
369 files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
371 [ List each fix as a =item entry ]
381 =head1 Known Problems
383 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
384 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
385 platform specific bugs also go here.
387 [ List each fix as a =item entry ]
397 =head1 Errata From Previous Releases
403 XXX Add anything here that we forgot to add, or were mistaken about, in
404 the perldelta of a previous release.
410 XXX If any significant core contributor has died, we've added a short obituary
413 =head1 Acknowledgements
415 XXX Generate this with:
417 perl Porting/acknowledgements.pl v5.25.5..HEAD
419 =head1 Reporting Bugs
421 If you find what you think is a bug, you might check the perl bug database
422 at L<https://rt.perl.org/> . There may also be information at
423 L<http://www.perl.org/> , the Perl Home Page.
425 If you believe you have an unreported bug, please run the L<perlbug> program
426 included with your release. Be sure to trim your bug down to a tiny but
427 sufficient test case. Your bug report, along with the output of C<perl -V>,
428 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
430 If the bug you are reporting has security implications which make it
431 inappropriate to send to a publicly archived mailing list, then see
432 L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
433 for details of how to report the issue.
437 If you wish to thank the Perl 5 Porters for the work we had done in Perl 5,
438 you can do so by running the C<perlthanks> program:
442 This will send an email to the Perl 5 Porters list with your show of thanks.
446 The F<Changes> file for an explanation of how to view exhaustive details on
449 The F<INSTALL> file for how to build Perl.
451 The F<README> file for general stuff.
453 The F<Artistic> and F<Copying> files for copyright information.