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 v5.17.2
12 This document describes differences between the 5.17.1 release and
15 If you are upgrading from an earlier release such as 5.17.0, first read
16 L<perl5171delta>, which describes differences between 5.17.0 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 ]
33 XXX Any security-related notices go here. In particular, any security
34 vulnerabilities closed should be noted here rather than in the
35 L</Selected Bug Fixes> section.
37 [ List each security issue as a =head2 entry ]
39 =head1 Incompatible Changes
41 XXX For a release on a stable branch, this section aspires to be:
43 There are no changes intentionally incompatible with 5.XXX.XXX
44 If any exist, they are bugs, and we request that you submit a
45 report. See L</Reporting Bugs> below.
47 [ List each incompatible change as a =head2 entry ]
51 XXX Any deprecated features, syntax, modules etc. should be listed here.
52 In particular, deprecated modules should be listed here even if they are
53 listed as an updated module in the L</Modules and Pragmata> section.
55 [ List each deprecation as a =head2 entry ]
57 =head1 Performance Enhancements
59 XXX Changes which enhance performance without changing behaviour go here. There
60 may well be none in a stable release.
62 [ List each enhancement as a =item entry ]
72 =head1 Modules and Pragmata
74 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
75 go here. If Module::CoreList is updated, generate an initial draft of the
76 following sections using F<Porting/corelist-perldelta.pl>, which prints stub
77 entries to STDOUT. Results can be pasted in place of the '=head2' entries
78 below. A paragraph summary for important changes should then be added by hand.
79 In an ideal world, dual-life modules would have a F<Changes> file that could be
82 [ Within each section, list entries as a =item entry ]
84 =head2 New Modules and Pragmata
94 =head2 Updated Modules and Pragmata
100 L<File::stat> has been upgraded from version 1.06 to 1.07.
102 Previously C<File::stat>'s overloaded C<-x> and C<-X> operators did not give
103 the correct results for directories or executable files when running as
104 root. They had been treating executable permissions for root just like for
105 any other user, performing group membership tests I<etc> for files not owned
106 by root. They now follow the correct Unix behaviour - for a directory they
107 are always true, and for a file if any of the three execute permission bits
108 are set then they report that root can execute the file. Perl's builtin
109 C<-x> and C<-X> operators have always been correct.
113 L<Tie::StdHandle> has been upgraded from version 4.2 to 4.3.
115 C<READ> now respects the offset argument to C<read> [perl #112826].
119 L<IO> has been upgraded from version 1.25_07 to 1.25_08.
121 L<IO::Socket> tries harder to cache or otherwise fetch socket
126 L<Storable> has been upgraded from version 2.36 to 2.37.
128 Restricted hashes were not always thawed correctly [perl #73972].
130 Storable would croak when freezing a blessed REF object with a
131 C<STORABLE_freeze()> method [perl #113880].
135 =head2 Removed Modules and Pragmata
147 XXX Changes to files in F<pod/> go here. Consider grouping entries by
148 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
150 =head2 New Documentation
152 XXX Changes which create B<new> files in F<pod/> go here.
156 XXX Description of the purpose of the new file here
158 =head2 Changes to Existing Documentation
160 XXX Changes which significantly change existing files in F<pod/> go here.
161 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
170 Clarified documentation of C<our>.
176 The following additions or changes have been made to diagnostic output,
177 including warnings and fatal error messages. For the complete list of
178 diagnostic messages, see L<perldiag>.
180 XXX New or changed warnings emitted by the core's C<C> code go here. Also
181 include any changes in L<perldiag> that reconcile it to the C<C> code.
183 [ Within each section, list entries as a =item entry that links to perldiag,
188 L<Invalid version object|perldiag/"Invalid version object">
191 =head2 New Diagnostics
193 XXX Newly added diagnostic messages go here
201 L<Group name must start with a non-digit word character in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Group name must start with a non-digit word character in regex; marked by <-- HERE in m/%s/">
203 This error has been added for C<(?&0)>, which is invalid. It used to
204 produce an incomprehensible error message [perl #101666].
214 C<chr()> now warns when passed a negative value [perl #83048].
218 C<srand()> now warns when passed a value that doesn't fit in a C<UV> (since the
219 value will be truncated rather than overflowing) [perl #40605].
223 Running perl with the C<-i> flag now warns if no input files are provided on
224 the command line [perl #113410].
228 =head2 Changes to Existing Diagnostics
230 XXX Changes (i.e. rewording) of diagnostic messages go here
236 XXX Describe change here
240 =head1 Utility Changes
242 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
243 here. Most of these are built within the directories F<utils> and F<x2p>.
245 [ List utility changes as a =head3 entry for each utility and =item
246 entries for each change
247 Use L<XXX> with program names to get proper documentation linking. ]
259 =head1 Configuration and Compilation
261 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
262 go here. Any other changes to the Perl build process should be listed here.
263 However, any platform-specific changes should be listed in the
264 L</Platform Support> section, instead.
266 [ List changes as a =item entry ].
272 Building perl with some Windows compilers used to fail due to a problem
273 with miniperl's C<glob> operator (which uses the C<perlglob> program)
274 deleting the PATH environment variable [perl #113798].
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 summarising, 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
317 =head2 Discontinued Platforms
319 XXX List any platforms that this version of perl no longer compiles on.
323 =item XXX-some-platform
329 =head2 Platform-Specific Notes
331 XXX List any changes for specific platforms. This could include configuration
332 and compilation changes or changes in portability/compatibility. However,
333 changes within modules for platforms should generally be listed in the
334 L</Modules and Pragmata> section.
340 Quotes are now removed from the command verb (but not the parameters) for commands
341 spawned via C<system>, backticks, or a piped C<open>. Previously, quotes on the verb
342 were passed through to DCL, which would fail to recognize the command. Also, if the
343 verb is actually a path to an image or command procedure on an ODS-5 volume, quoting it
344 now allows the path to contain spaces.
348 Configure now always adds -qlanglvl=extc99 to the CC flags on AIX when
349 using xlC. This will make it easier to compile a number of XS-based modules
350 that assume C99 [perl #113778].
354 =head1 Internal Changes
356 XXX Changes which affect the interface available to C<XS> code go here.
357 Other significant internal changes for future core maintainers should
360 [ List each change as a =item entry ]
366 OP allocation for CVs now uses a slab allocator. This simplifies
367 memory management for OPs allocated to a CV, so cleaning up after a
368 compilation error is simpler and safer [perl #111462][perl #112312].
372 =head1 Selected Bug Fixes
374 XXX Important bug fixes in the core language are summarised here.
375 Bug fixes in files in F<ext/> and F<lib/> are best summarised in
376 L</Modules and Pragmata>.
378 [ List each fix as a =item entry ]
384 A regression introduced in v5.14.0 has been fixed, in which some calls
385 to the C<re> module would clobber C<$_> [perl #113750].
389 C<do FILE> now always either sets or clears C<$@>, even when the file can't be
390 read. This ensures that testing C<$@> first (as recommended by the
391 documentation) always returns the correct result.
395 The array iterator used for the C<each @array> construct is now correctly
396 reset when C<@array> is cleared (RT #75596). This happens for example when the
397 array is globally assigned to, as in C<@array = (...)>, but not when its
398 B<values> are assigned to. In terms of the XS API, it means that C<av_clear()>
399 will now reset the iterator.
401 This mirrors the behaviour of the hash iterator when the hash is cleared.
405 C<< $class->can >>, C<< $class->isa >>, and C<< $class->DOES >> now return
406 correct results, regardless of whether that package referred to by C<$class>
407 exists [perl #47113].
411 Arriving signals no longer clear C<$@> [perl #45173].
415 Allow C<my ()> declarations with an empty variable list [perl #113554].
419 During parsing, subs declared after errors no longer leave stubs
424 Closures containing no string evals no longer hang on to their containing
425 subroutines, allowing variables closed over by outer subroutines to be
426 freed when the outer sub is freed, even if the inner sub still exists
431 Duplication of in-memory filehandles by opening with a "<&=" or ">&=" mode
432 stopped working properly in 5.16.0. It was causing the new handle to
433 reference a different scalar variable. This has been fixed [perl #113764].
437 C<qr//> expressions no longer crash with custom regular expression engines
438 that do not set C<offs> at regular expression compilation time
443 C<delete local> no longer crashes with certain magical arrays and hashes
448 C<local> on elements of certain magical arrays and hashes used not to
449 arrange to have the element deleted on scope exit, even if the element did
450 not exist before C<local>.
454 C<scalar(write)> no longer returns multiple items [perl #73690].
458 String to floating point conversions no longer misparse certain strings under
459 C<use locale> [perl #109318].
463 C<@INC> filters that die no longer leak memory [perl #92252].
467 The implementations of overloaded operations are now called in the correct
468 context. This allows, among other things, being able to properly override
469 C<< <> >> [perl #47119].
473 Specifying only the C<fallback> key when calling C<use overload> now behaves
474 properly [perl #113010].
478 C<< sub foo { my $a = 0; while ($a) { ... } } >> and
479 C<< sub foo { while (0) { ... } } >> now return the same thing [perl #73618].
483 Fixed the debugger C<l> and C<M> commands, and other debugger
484 functionality which was broken in 5.17.0 [perl #113918].
488 String negation now behaves the same under C<use integer;> as it does
489 without [perl #113012].
493 =head1 Known Problems
495 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
496 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
497 platform specific bugs also go here.
499 [ List each fix as a =item entry ]
511 XXX If any significant core contributor has died, we've added a short obituary
514 =head1 Acknowledgements
516 XXX Generate this with:
518 perl Porting/acknowledgements.pl v5.17.1..HEAD
520 =head1 Reporting Bugs
522 If you find what you think is a bug, you might check the articles
523 recently posted to the comp.lang.perl.misc newsgroup and the perl
524 bug database at http://rt.perl.org/perlbug/ . There may also be
525 information at http://www.perl.org/ , the Perl Home Page.
527 If you believe you have an unreported bug, please run the L<perlbug>
528 program included with your release. Be sure to trim your bug down
529 to a tiny but sufficient test case. Your bug report, along with the
530 output of C<perl -V>, will be sent off to perlbug@perl.org to be
531 analysed by the Perl porting team.
533 If the bug you are reporting has security implications, which make it
534 inappropriate to send to a publicly archived mailing list, then please send
535 it to perl5-security-report@perl.org. This points to a closed subscription
536 unarchived mailing list, which includes
537 all the core committers, who will be able
538 to help assess the impact of issues, figure out a resolution, and help
539 co-ordinate the release of patches to mitigate or fix the problem across all
540 platforms on which Perl is supported. Please only use this address for
541 security issues in the Perl core, not for modules independently
546 The F<Changes> file for an explanation of how to view exhaustive details
549 The F<INSTALL> file for how to build Perl.
551 The F<README> file for general stuff.
553 The F<Artistic> and F<Copying> files for copyright information.