5 [ this is a template for a new perldelta file. Any text flagged as
6 XXX needs to be processed before release. ]
8 perldelta - what is new for perl v5.17.3
12 This document describes differences between the 5.17.2 release and
15 If you are upgrading from an earlier release such as 5.17.1, first read
16 L<perl5172delta>, which describes differences between 5.17.1 and
21 XXX Any important notices here
23 =head1 Core Enhancements
25 XXX New core language features go here. Summarise user-visible core language
26 enhancements. Particularly prominent performance optimisations could go
27 here, but most should go in the L</Performance Enhancements> section.
29 [ List each enhancement as a =head2 entry ]
31 =head2 Computed Labels
33 The loop controls C<next>, C<last> and C<redo>, and the special C<dump>
34 operator, now allow arbitrary expressions to be used to compute labels at
35 run time. Previously, any argument that was not a constant was treated as
40 XXX Any security-related notices go here. In particular, any security
41 vulnerabilities closed should be noted here rather than in the
42 L</Selected Bug Fixes> section.
44 [ List each security issue as a =head2 entry ]
46 =head1 Incompatible Changes
48 [ List each incompatible change as a =head2 entry ]
50 =head2 C<$ENV{foo} = undef> deletes value from environ, like C<delete $ENV{foo}>
52 This facilitates use of C<local()> with C<%ENV> entries. In previous
53 versions of Perl, C<undef> was converted to the empty string.
55 =head2 Defined values stored in environment are forced to byte strings
57 A value stored in an environment variable has always been stringified. In
58 this release, it is converted to be only a byte string. First, it is forced
59 to be a only a string. Then if the string is utf8 and the equivalent of
60 C<utf8::downgrade> works, that result is used; otherwise, the equivalent of
61 C<utf8::encode> is used, and a warning is issued about wide characters
66 XXX Any deprecated features, syntax, modules etc. should be listed here.
67 In particular, deprecated modules should be listed here even if they are
68 listed as an updated module in the L</Modules and Pragmata> section.
70 [ List each deprecation as a =head2 entry ]
72 =head1 Performance Enhancements
74 XXX Changes which enhance performance without changing behaviour go here. There
75 may well be none in a stable release.
77 [ List each enhancement as a =item entry ]
87 =head1 Modules and Pragmata
89 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
90 go here. If Module::CoreList is updated, generate an initial draft of the
91 following sections using F<Porting/corelist-perldelta.pl>, which prints stub
92 entries to STDOUT. Results can be pasted in place of the '=head2' entries
93 below. A paragraph summary for important changes should then be added by hand.
94 In an ideal world, dual-life modules would have a F<Changes> file that could be
97 [ Within each section, list entries as a =item entry ]
99 =head2 New Modules and Pragmata
109 =head2 Updated Modules and Pragmata
115 L<B> has been upgraded from version 1.36 to version 1.37. All C<CVf_*> and
116 C<GVf_*> and more SV-related flag values are now provided as constants in
117 the C<B::> namespace and available for export. The default export list has
122 L<B::Deparse> has been upgraded from version 1.15 to 1.16. It now deparses
123 loop controls with the correct precedence.
127 =head2 Removed Modules and Pragmata
139 XXX Changes to files in F<pod/> go here. Consider grouping entries by
140 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
142 =head2 New Documentation
144 XXX Changes which create B<new> files in F<pod/> go here.
148 XXX Description of the purpose of the new file here
150 =head2 Changes to Existing Documentation
152 XXX Changes which significantly change existing files in F<pod/> go here.
153 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
156 =head3 L<perlfunc>, L<perlop>
162 Loop control verbs (C<dump>, C<goto>, C<next>, C<last> and C<redo>) have
163 always had the same precedence as assignment operators, but this was never
164 documented until now.
170 The following additions or changes have been made to diagnostic output,
171 including warnings and fatal error messages. For the complete list of
172 diagnostic messages, see L<perldiag>.
174 XXX New or changed warnings emitted by the core's C<C> code go here. Also
175 include any changes in L<perldiag> that reconcile it to the C<C> code.
177 [ Within each section, list entries as a =item entry that links to perldiag,
182 L<Invalid version object|perldiag/"Invalid version object">
185 =head2 New Diagnostics
187 XXX Newly added diagnostic messages go here
193 Attempts to put wide characters into environment variables via %ENV provoke
194 the warning "Wide character in setenv".
204 XXX L<message|perldiag/"message">
214 XXX L<message|perldiag/"message">
218 =head2 Changes to Existing Diagnostics
220 XXX Changes (i.e. rewording) of diagnostic messages go here
226 XXX Describe change here
230 =head1 Utility Changes
232 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
233 here. Most of these are built within the directories F<utils> and F<x2p>.
235 [ List utility changes as a =head3 entry for each utility and =item
236 entries for each change
237 Use L<XXX> with program names to get proper documentation linking. ]
249 =head1 Configuration and Compilation
251 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
252 go here. Any other changes to the Perl build process should be listed here.
253 However, any platform-specific changes should be listed in the
254 L</Platform Support> section, instead.
256 [ List changes as a =item entry ].
268 XXX Any significant changes to the testing of a freshly built perl should be
269 listed here. Changes which create B<new> files in F<t/> go here as do any
270 large changes to the testing harness (e.g. when parallel testing was added).
271 Changes to existing files in F<t/> aren't worth summarising, although the bugs
272 that they represent may be covered elsewhere.
274 [ List each test improvement as a =item entry ]
284 =head1 Platform Support
286 XXX Any changes to platform support should be listed in the sections below.
288 [ Within the sections, list each platform as a =item entry with specific
289 changes as paragraphs below it. ]
293 XXX List any platforms that this version of perl compiles on, that previous
294 versions did not. These will either be enabled by new files in the F<hints/>
295 directories, or new subdirectories and F<README> files at the top level of the
300 =item XXX-some-platform
306 =head2 Discontinued Platforms
308 XXX List any platforms that this version of perl no longer compiles on.
312 =item XXX-some-platform
318 =head2 Platform-Specific Notes
320 XXX List any changes for specific platforms. This could include configuration
321 and compilation changes or changes in portability/compatibility. However,
322 changes within modules for platforms should generally be listed in the
323 L</Modules and Pragmata> section.
327 =item XXX-some-platform
333 =head1 Internal Changes
335 XXX Changes which affect the interface available to C<XS> code go here.
336 Other significant internal changes for future core maintainers should
339 [ List each change as a =item entry ]
349 =head1 Selected Bug Fixes
351 XXX Important bug fixes in the core language are summarised here.
352 Bug fixes in files in F<ext/> and F<lib/> are best summarised in
353 L</Modules and Pragmata>.
355 [ List each fix as a =item entry ]
361 C<\w> now matches the code points U+200C (ZERO WIDTH NON-JOINER) and
362 U+200D (ZERO WIDTH JOINER). C<\W> no longer matches these. This change
363 is because Unicode corrected their definition of what C<\w> should match.
367 C<dump LABEL> no longer leaks its label.
371 Constant folding no longer changes the behaviour of functions like C<stat>
372 and C<truncate> that can take either filenames or handles.
373 C<stat 1 ? foo : bar> nows treats its argument as a file name (since it is
374 an arbitrary expression), rather than the handle "foo".
378 C<truncate FOO, $len> no longer falls back to treating "FOO" as a file name
379 if the filehandle has been deleted. This was broken in Perl 5.16.0.
383 Subroutine redefinitions after sub-to-glob and glob-to-glob assignments no
384 longer cause double frees or panic messages.
388 C<s///> now turns vstrings into plain strings when performing a
389 substitution, even if the resulting string is the same (C<s/a/a/>).
393 Prototype mismatch warnings no longer erroneously treat constant subs as
394 having no prototype when they actually have "".
398 Constant subroutines and forward declarations no longer prevent prototype
399 mismatch warnings from omitting the sub name.
403 C<undef> on a subroutine now clears call checkers.
407 =head1 Known Problems
409 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
410 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
411 platform specific bugs also go here.
413 [ List each fix as a =item entry ]
425 XXX If any significant core contributor has died, we've added a short obituary
428 =head1 Acknowledgements
430 XXX Generate this with:
432 perl Porting/acknowledgements.pl v5.17.2..HEAD
434 =head1 Reporting Bugs
436 If you find what you think is a bug, you might check the articles
437 recently posted to the comp.lang.perl.misc newsgroup and the perl
438 bug database at http://rt.perl.org/perlbug/ . There may also be
439 information at http://www.perl.org/ , the Perl Home Page.
441 If you believe you have an unreported bug, please run the L<perlbug>
442 program included with your release. Be sure to trim your bug down
443 to a tiny but sufficient test case. Your bug report, along with the
444 output of C<perl -V>, will be sent off to perlbug@perl.org to be
445 analysed by the Perl porting team.
447 If the bug you are reporting has security implications, which make it
448 inappropriate to send to a publicly archived mailing list, then please send
449 it to perl5-security-report@perl.org. This points to a closed subscription
450 unarchived mailing list, which includes
451 all the core committers, who will be able
452 to help assess the impact of issues, figure out a resolution, and help
453 co-ordinate the release of patches to mitigate or fix the problem across all
454 platforms on which Perl is supported. Please only use this address for
455 security issues in the Perl core, not for modules independently
460 The F<Changes> file for an explanation of how to view exhaustive details
463 The F<INSTALL> file for how to build Perl.
465 The F<README> file for general stuff.
467 The F<Artistic> and F<Copying> files for copyright information.