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 v5.23.1
12 This document describes differences between the 5.23.0 release and the 5.23.1
15 If you are upgrading from an earlier release such as 5.22.0, first read
16 L<perl5230delta>, which describes differences between 5.22.0 and 5.23.0.
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 ]
30 =head2 Integer shift (C<< << >> and C<< >> >>) now explicitly defined
32 Negative shifts are reverse shifts: left shift becomes right shift,
33 and right shift becomes left shift.
35 Shifting by the number of bits in a native integer (or more) is zero,
36 except when the "overshift" is right shifting a negative value under
37 C<use integer>, in which case the result is -1 (arithmetic shift).
39 Until now negative shifting and overshifting have been undefined
40 because they have relied on whatever the C implementation happens
41 to do. For example, for the "overshift" a common behavior C is
44 1 >> 64 == 1 >> (64 % 64) == 1 >> 0 == 1 # Common C behavior.
46 # And the same for <<, while Perl now produces 0 for both.
48 Now these behaviors are well-defined under Perl, regardless of what
49 the underlying C implementation does. Note, however, that you cannot
50 escape the native integer width. If you need more bits on the left shift,
51 you could use the C<bigint> pragma.
53 =head2 Postfix dereferencing is no longer experimental
55 Using the C<postderef> and C<postderef_qq> features no longer emits a warning.
56 Existing code that disables that warning category will continue to work. The
57 C<5.24> feature bundle now includes those features.
61 XXX Any security-related notices go here. In particular, any security
62 vulnerabilities closed should be noted here rather than in the
63 L</Selected Bug Fixes> section.
65 [ List each security issue as a =head2 entry ]
67 =head1 Incompatible Changes
69 XXX For a release on a stable branch, this section aspires to be:
71 There are no changes intentionally incompatible with 5.XXX.XXX
72 If any exist, they are bugs, and we request that you submit a
73 report. See L</Reporting Bugs> below.
75 [ List each incompatible change as a =head2 entry ]
79 XXX Any deprecated features, syntax, modules etc. should be listed here.
81 =head2 Module removals
83 XXX Remove this section if inapplicable.
85 The following modules will be removed from the core distribution in a
86 future release, and will at that time need to be installed from CPAN.
87 Distributions on CPAN which require these modules will need to list them as
90 The core versions of these modules will now issue C<"deprecated">-category
91 warnings to alert you to this fact. To silence these deprecation warnings,
92 install the modules in question from CPAN.
94 Note that these are (with rare exceptions) fine modules that you are encouraged
95 to continue to use. Their disinclusion from core primarily hinges on their
96 necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
97 not usually on concerns over their design.
103 XXX Note that deprecated modules should be listed here even if they are listed
104 as an updated module in the L</Modules and Pragmata> section.
108 [ List each other deprecation as a =head2 entry ]
110 =head1 Performance Enhancements
112 XXX Changes which enhance performance without changing behaviour go here.
113 There may well be none in a stable release.
115 [ List each enhancement as a =item entry ]
125 =head1 Modules and Pragmata
127 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
128 go here. If Module::CoreList is updated, generate an initial draft of the
129 following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
130 for important changes should then be added by hand. In an ideal world,
131 dual-life modules would have a F<Changes> file that could be cribbed.
133 [ Within each section, list entries as a =item entry ]
135 =head2 New Modules and Pragmata
145 =head2 Updated Modules and Pragmata
151 L<IPC::Open3> has been upgraded from version 1.18 to 1.19.
153 If a Perl exception was thrown from inside this module, the exception
154 C<IPC::Open3> threw to the callers of C<open3> would have an irrelavent
155 message derived from C<$!> which was in an undefined state, instead of the
156 C<$@> message which triggers the failure path inside C<open3>.
160 =head2 Removed Modules and Pragmata
172 XXX Changes to files in F<pod/> go here. Consider grouping entries by
173 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
175 =head2 New Documentation
177 XXX Changes which create B<new> files in F<pod/> go here.
181 XXX Description of the purpose of the new file here
183 =head2 Changes to Existing Documentation
185 XXX Changes which significantly change existing files in F<pod/> go here.
186 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
195 XXX Description of the change here
201 The following additions or changes have been made to diagnostic output,
202 including warnings and fatal error messages. For the complete list of
203 diagnostic messages, see L<perldiag>.
205 XXX New or changed warnings emitted by the core's C<C> code go here. Also
206 include any changes in L<perldiag> that reconcile it to the C<C> code.
208 =head2 New Diagnostics
210 XXX Newly added diagnostic messages go under here, separated into New Errors
219 XXX L<message|perldiag/"message">
229 XXX L<message|perldiag/"message">
233 =head2 Changes to Existing Diagnostics
235 XXX Changes (i.e. rewording) of diagnostic messages go here
241 XXX Describe change here
245 =head1 Utility Changes
247 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
248 Most of these are built within the directory F<utils>.
250 [ List utility changes as a =head2 entry for each utility and =item
251 entries for each change
252 Use L<XXX> with program names to get proper documentation linking. ]
264 =head1 Configuration and Compilation
266 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
267 go here. Any other changes to the Perl build process should be listed here.
268 However, any platform-specific changes should be listed in the
269 L</Platform Support> section, instead.
271 [ List changes as a =item entry ].
283 XXX Any significant changes to the testing of a freshly built perl should be
284 listed here. Changes which create B<new> files in F<t/> go here as do any
285 large changes to the testing harness (e.g. when parallel testing was added).
286 Changes to existing files in F<t/> aren't worth summarizing, although the bugs
287 that they represent may be covered elsewhere.
289 [ List each test improvement as a =item entry ]
299 =head1 Platform Support
301 XXX Any changes to platform support should be listed in the sections below.
303 [ Within the sections, list each platform as a =item entry with specific
304 changes as paragraphs below it. ]
308 XXX List any platforms that this version of perl compiles on, that previous
309 versions did not. These will either be enabled by new files in the F<hints/>
310 directories, or new subdirectories and F<README> files at the top level of the
315 =item XXX-some-platform
321 =head2 Discontinued Platforms
323 XXX List any platforms that this version of perl no longer compiles on.
327 =item XXX-some-platform
333 =head2 Platform-Specific Notes
335 XXX List any changes for specific platforms. This could include configuration
336 and compilation changes or changes in portability/compatibility. However,
337 changes within modules for platforms should generally be listed in the
338 L</Modules and Pragmata> section.
348 The minimum supported version of VMS is now v7.3-2, released in 2003. As a
349 side effect of this change, VAX is no longer supported as the terminal
350 release of OpenVMS VAX was v7.3 in 2001.
356 =head1 Internal Changes
358 XXX Changes which affect the interface available to C<XS> code go here. Other
359 significant internal changes for future core maintainers should be noted as
362 [ List each change as a =item entry ]
372 =head1 Selected Bug Fixes
374 XXX Important bug fixes in the core language are summarized here. Bug fixes in
375 files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
377 [ List each fix as a =item entry ]
383 A leak in the XS typemap caused one scalar to be leaked each time a C<FILE *>
384 or a C<PerlIO *> was C<OUTPUT:>ed or imported to Perl, since perl 5.000. These
385 particular typemap entries are thought to be extremely rarely used by XS
386 modules. [perl #124181]
390 =head1 Known Problems
392 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
393 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
394 platform specific bugs also go here.
396 [ List each fix as a =item entry ]
406 =head1 Errata From Previous Releases
412 XXX Add anything here that we forgot to add, or were mistaken about, in
413 the perldelta of a previous release.
419 XXX If any significant core contributor has died, we've added a short obituary
422 =head1 Acknowledgements
424 XXX Generate this with:
426 perl Porting/acknowledgements.pl v5.23.1..HEAD
428 =head1 Reporting Bugs
430 If you find what you think is a bug, you might check the articles recently
431 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
432 L<https://rt.perl.org/> . There may also be information at
433 L<http://www.perl.org/> , the Perl Home Page.
435 If you believe you have an unreported bug, please run the L<perlbug> program
436 included with your release. Be sure to trim your bug down to a tiny but
437 sufficient test case. Your bug report, along with the output of C<perl -V>,
438 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
440 If the bug you are reporting has security implications, which make it
441 inappropriate to send to a publicly archived mailing list, then please send it
442 to perl5-security-report@perl.org. This points to a closed subscription
443 unarchived mailing list, which includes all the core committers, who will be
444 able to help assess the impact of issues, figure out a resolution, and help
445 co-ordinate the release of patches to mitigate or fix the problem across all
446 platforms on which Perl is supported. Please only use this address for
447 security issues in the Perl core, not for modules independently distributed on
452 The F<Changes> file for an explanation of how to view exhaustive details on
455 The F<INSTALL> file for how to build Perl.
457 The F<README> file for general stuff.
459 The F<Artistic> and F<Copying> files for copyright information.