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perldelta for 317f3b6
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1=encoding utf8
2
3=head1 NAME
4
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5[ this is a template for a new perldelta file. Any text flagged as
6XXX needs to be processed before release. ]
27f00e3d 7
e96e0834 8perldelta - what is new for perl v5.17.2
417a992d 9
e96e0834 10=head1 DESCRIPTION
028c8719 11
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12This document describes differences between the 5.17.1 release and
13the 5.17.2 release.
028c8719 14
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15If you are upgrading from an earlier release such as 5.17.0, first read
16L<perl5171delta>, which describes differences between 5.17.0 and
175.17.1.
028c8719 18
e96e0834 19=head1 Notice
30608892 20
e96e0834 21XXX Any important notices here
e128ab2c 22
e96e0834 23=head1 Core Enhancements
e128ab2c 24
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25XXX New core language features go here. Summarise user-visible core language
26enhancements. Particularly prominent performance optimisations could go
27here, but most should go in the L</Performance Enhancements> section.
fe3193b5 28
e96e0834 29[ List each enhancement as a =head2 entry ]
05c8f9ed 30
e96e0834 31=head1 Security
0da72d5e 32
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33XXX Any security-related notices go here. In particular, any security
34vulnerabilities closed should be noted here rather than in the
35L</Selected Bug Fixes> section.
0da72d5e 36
e96e0834 37[ List each security issue as a =head2 entry ]
0da72d5e 38
e96e0834 39=head1 Incompatible Changes
0da72d5e 40
e96e0834 41XXX For a release on a stable branch, this section aspires to be:
0da72d5e 42
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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.
0da72d5e 46
e96e0834 47[ List each incompatible change as a =head2 entry ]
e2f0c3bb 48
e96e0834 49=head1 Deprecations
e2f0c3bb 50
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51XXX Any deprecated features, syntax, modules etc. should be listed here.
52In particular, deprecated modules should be listed here even if they are
53listed as an updated module in the L</Modules and Pragmata> section.
7d101ed1 54
e96e0834 55[ List each deprecation as a =head2 entry ]
7d101ed1 56
e96e0834 57=head1 Performance Enhancements
7d101ed1 58
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59XXX Changes which enhance performance without changing behaviour go here. There
60may well be none in a stable release.
7d101ed1 61
e96e0834 62[ List each enhancement as a =item entry ]
95ce428c 63
f9001595 64=over 4
75ff5956 65
2630d42b 66=item *
c11980ad 67
e96e0834 68XXX
53de3ff0 69
61174fb5 70=back
ef7131e9 71
61174fb5 72=head1 Modules and Pragmata
ef7131e9 73
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74XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
75go here. If Module::CoreList is updated, generate an initial draft of the
76following sections using F<Porting/corelist-perldelta.pl>, which prints stub
77entries to STDOUT. Results can be pasted in place of the '=head2' entries
78below. A paragraph summary for important changes should then be added by hand.
79In an ideal world, dual-life modules would have a F<Changes> file that could be
80cribbed.
5cefbec9 81
e96e0834 82[ Within each section, list entries as a =item entry ]
fbdb83f3 83
e96e0834 84=head2 New Modules and Pragmata
95c6c5c5 85
e96e0834 86=over 4
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87
88=item *
89
e96e0834 90XXX
95c6c5c5 91
e96e0834 92=back
ff3f295c 93
e96e0834 94=head2 Updated Modules and Pragmata
ff3f295c 95
e96e0834 96=over 4
95c6c5c5 97
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98=item *
99
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100L<File::stat> has been upgraded from version 1.06 to 1.07.
101
102Previously C<File::stat>'s overloaded C<-x> and C<-X> operators did not give
103the correct results for directories or executable files when running as
104root. They had been treating executable permissions for root just like for
105any other user, performing group membership tests I<etc> for files not owned
106by root. They now follow the correct Unix behaviour - for a directory they
107are always true, and for a file if any of the three execute permission bits
108are set then they report that root can execute the file. Perl's builtin
109C<-x> and C<-X> operators have always been correct.
c506fc7e 110
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111=item *
112
113L<Tie::StdHandle> has been upgraded from version 4.2 to 4.3.
114
115C<READ> now respects the offset argument to C<read> [perl #112826].
116
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117=item *
118
119L<IO> has been upgraded from version 1.25_07 to 1.25_08.
120
121L<IO::Socket> tries harder to cache or otherwise fetch socket
122information.
123
e96e0834 124=back
c506fc7e 125
e96e0834 126=head2 Removed Modules and Pragmata
c506fc7e 127
e96e0834 128=over 4
95c6c5c5 129
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130=item *
131
e96e0834 132XXX
95c6c5c5 133
e96e0834 134=back
95c6c5c5 135
e96e0834 136=head1 Documentation
95c6c5c5 137
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138XXX Changes to files in F<pod/> go here. Consider grouping entries by
139file and be sure to link to the appropriate page, e.g. L<perlfunc>.
95c6c5c5 140
e96e0834 141=head2 New Documentation
1c633914 142
e96e0834 143XXX Changes which create B<new> files in F<pod/> go here.
f558db2f 144
e96e0834 145=head3 L<XXX>
66aa79e2 146
e96e0834 147XXX Description of the purpose of the new file here
95c6c5c5 148
e96e0834 149=head2 Changes to Existing Documentation
95c6c5c5 150
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151XXX Changes which significantly change existing files in F<pod/> go here.
152However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
153section.
95c6c5c5 154
e96e0834 155=head3 L<XXX>
95c6c5c5 156
e96e0834 157=over 4
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158
159=item *
160
e96e0834 161XXX Description of the change here
95c6c5c5 162
e96e0834 163=back
95c6c5c5 164
e96e0834 165=head1 Diagnostics
95c6c5c5 166
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167The following additions or changes have been made to diagnostic output,
168including warnings and fatal error messages. For the complete list of
169diagnostic messages, see L<perldiag>.
95c6c5c5 170
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171XXX New or changed warnings emitted by the core's C<C> code go here. Also
172include any changes in L<perldiag> that reconcile it to the C<C> code.
71014848 173
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174[ Within each section, list entries as a =item entry that links to perldiag,
175 e.g.
71014848 176
e96e0834 177 =item *
95c6c5c5 178
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179 L<Invalid version object|perldiag/"Invalid version object">
180]
95c6c5c5 181
e96e0834 182=head2 New Diagnostics
95c6c5c5 183
e96e0834 184XXX Newly added diagnostic messages go here
95c6c5c5 185
e96e0834 186=head3 New Errors
95c6c5c5 187
e96e0834 188=over 4
95c6c5c5 189
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190=item *
191
a9be10f4 192L<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/">
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193
194This error has been added for C<(?&0)>, which is invalid. It used to
195produce an incomprehensible error message [perl #101666].
95c6c5c5 196
e96e0834 197=back
95c6c5c5 198
e96e0834 199=head3 New Warnings
95c6c5c5 200
e96e0834 201=over 4
95c6c5c5 202
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203=item *
204
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205C<chr()> now warns when passed a negative value [perl #83048].
206
207=item *
208
209C<srand()> now warns when passed a value that doesn't fit in a C<UV> (since the
210value will be truncated rather than overflowing) [perl #40605].
7d101ed1 211
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212=item *
213
214Running perl with the C<-i> flag now warns if no input files are provided on
215the command line [perl #113410].
216
e96e0834 217=back
d9661073 218
e96e0834 219=head2 Changes to Existing Diagnostics
95c6c5c5 220
e96e0834 221XXX Changes (i.e. rewording) of diagnostic messages go here
95c6c5c5 222
e96e0834 223=over 4
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224
225=item *
226
e96e0834 227XXX Describe change here
3630f57e 228
e96e0834 229=back
3630f57e 230
e96e0834 231=head1 Utility Changes
95c6c5c5 232
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233XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
234here. Most of these are built within the directories F<utils> and F<x2p>.
95c6c5c5 235
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236[ List utility changes as a =head3 entry for each utility and =item
237entries for each change
238Use L<XXX> with program names to get proper documentation linking. ]
95c6c5c5 239
e96e0834 240=head3 L<XXX>
95c6c5c5 241
e96e0834 242=over 4
95c6c5c5
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243
244=item *
245
e96e0834 246XXX
95c6c5c5 247
e96e0834 248=back
95c6c5c5 249
e96e0834 250=head1 Configuration and Compilation
95c6c5c5 251
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252XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
253go here. Any other changes to the Perl build process should be listed here.
254However, any platform-specific changes should be listed in the
255L</Platform Support> section, instead.
95c6c5c5 256
e96e0834 257[ List changes as a =item entry ].
95c6c5c5 258
e96e0834 259=over 4
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260
261=item *
262
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263Building perl with some Windows compilers used to fail due to a problem
264with miniperl's C<glob> operator (which uses the C<perlglob> program)
265deleting the PATH environment variable [perl #113798].
95c6c5c5 266
e96e0834 267=back
95c6c5c5 268
e96e0834 269=head1 Testing
95c6c5c5 270
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271XXX Any significant changes to the testing of a freshly built perl should be
272listed here. Changes which create B<new> files in F<t/> go here as do any
273large changes to the testing harness (e.g. when parallel testing was added).
274Changes to existing files in F<t/> aren't worth summarising, although the bugs
275that they represent may be covered elsewhere.
95c6c5c5 276
e96e0834 277[ List each test improvement as a =item entry ]
95c6c5c5 278
e96e0834 279=over 4
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280
281=item *
282
e96e0834 283XXX
95c6c5c5 284
61174fb5 285=back
f558db2f 286
e96e0834 287=head1 Platform Support
05c8f9ed 288
e96e0834 289XXX Any changes to platform support should be listed in the sections below.
05c8f9ed 290
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291[ Within the sections, list each platform as a =item entry with specific
292changes as paragraphs below it. ]
9dea6244 293
e96e0834 294=head2 New Platforms
9dea6244 295
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296XXX List any platforms that this version of perl compiles on, that previous
297versions did not. These will either be enabled by new files in the F<hints/>
298directories, or new subdirectories and F<README> files at the top level of the
299source tree.
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300
301=over 4
302
b81e0e29 303=item *
7d101ed1 304
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305Configure now always adds -qlanglvl=extc99 to the CC flags on AIX when
306using xlC. This will make it easier to compile a number of XS-based modules
307that assume C99 [perl #113778].
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308
309=back
310
e96e0834 311=head2 Discontinued Platforms
ef7131e9 312
e96e0834 313XXX List any platforms that this version of perl no longer compiles on.
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314
315=over 4
316
e96e0834 317=item XXX-some-platform
8dffc0ab 318
e96e0834 319XXX
dbc84d79 320
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321=back
322
61174fb5 323=head2 Platform-Specific Notes
ceb0881c 324
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325XXX List any changes for specific platforms. This could include configuration
326and compilation changes or changes in portability/compatibility. However,
327changes within modules for platforms should generally be listed in the
328L</Modules and Pragmata> section.
89cbc6b8 329
e96e0834 330=over 4
0998713f 331
e96e0834 332=item XXX-some-platform
112b6866 333
e96e0834 334XXX
112b6866 335
61174fb5 336=back
8e125188 337
61174fb5 338=head1 Internal Changes
8e125188 339
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340XXX Changes which affect the interface available to C<XS> code go here.
341Other significant internal changes for future core maintainers should
342be noted as well.
c4643160 343
e96e0834 344[ List each change as a =item entry ]
f8ef51fd 345
e96e0834 346=over 4
e128ab2c 347
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348=item *
349
e96e0834 350XXX
e2f0c3bb 351
61174fb5 352=back
422287bf 353
61174fb5 354=head1 Selected Bug Fixes
2de6ba8d 355
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356XXX Important bug fixes in the core language are summarised here.
357Bug fixes in files in F<ext/> and F<lib/> are best summarised in
358L</Modules and Pragmata>.
52c4b146 359
e96e0834 360[ List each fix as a =item entry ]
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361
362=over 4
363
364=item *
365
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366A regression introduced in v5.14.0 has been fixed, in which some calls
367to the C<re> module would clobber C<$_>.
e128ab2c 368
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369=item *
370
371C<do FILE> now always either sets or clears C<$@>, even when the file can't be
372read. This ensures that testing C<$@> first (as recommended by the
373documentation) always returns the correct result.
374
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375=item *
376
377The array iterator used for the C<each @array> construct is now correctly
378reset when C<@array> is cleared (RT #75596). This happens for example when the
379array is globally assigned to, as in C<@array = (...)>, but not when its
380B<values> are assigned to. In terms of the XS API, it means that C<av_clear()>
381will now reset the iterator.
382
383This mirrors the behaviour of the hash iterator when the hash is cleared.
384
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385=item *
386
387C<< $class->can >>, C<< $class->isa >>, and C<< $class->DOES >> now return
388correct results, regardless of whether that package referred to by C<$class>
389exists [perl #47113].
390
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391=item *
392
393Arriving signals no longer clear C<$@> [perl #45173].
394
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395=item *
396
397Allow C<my ()> declarations with an empty variable list [perl #113554].
398
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399=item *
400
401During parsing, subs declared after errors no longer leave stubs
402[perl #113712].
403
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404=item *
405
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406Closures containing no string evals no longer hang on to their containing
407subroutines, allowing variables closed over by outer subroutines to be
408freed when the outer sub is freed, even if the inner sub still exists
409[perl #89544].
410
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411=item *
412
413Duplication of in-memory filehandles by opening with a "<&=" or ">&=" mode
414stopped working properly in 5.16.0. It was causing the new handle to
415reference a different scalar variable. This has been fixed [perl #113764].
416
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417=item *
418
419C<qr//> expressions no longer crash with custom regular expression engines
420that do not set C<offs> at regular expression compilation time
421[perl #112962].
422
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423=item *
424
425C<delete local> no longer crashes with certain magical arrays and hashes
426[perl #112966].
427
428=item *
429
430C<local> on elements of certain magical arrays and hashes used not to
431arrange to have the element deleted on scope exit, even if the element did
432not exist before C<local>.
433
434=item *
435
436C<scalar(write)> no longer returns multiple items [perl #73690].
437
438=item *
439
440String to floating point conversions no longer misparse certain strings under
441C<use locale> [perl #109318].
442
443=item *
444
445C<@INC> filters that die no longer leak memory [perl #92252].
446
447=item *
448
449The implementations of overloaded operations are now called in the correct
450context. This allows, among other things, being able to properly override
451C<< <> >> [perl #47119].
452
453=item *
454
455Specifying only the C<fallback> key when calling C<use overload> now behaves
456properly [perl #113010].
457
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458=item *
459
460C<< sub foo { my $a = 0; while ($a) { ... } } >> and
461C<< sub foo { while (0) { ... } } >> now return the same thing [perl #73618].
462
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463=back
464
e96e0834 465=head1 Known Problems
dbc84d79 466
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467XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
468tests that had to be C<TODO>ed for the release would be noted here. Unfixed
469platform specific bugs also go here.
53de3ff0 470
e96e0834 471[ List each fix as a =item entry ]
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472
473=over 4
474
475=item *
476
e96e0834 477XXX
233bba44 478
e96e0834 479=back
233bba44 480
e96e0834 481=head1 Obituary
233bba44 482
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483XXX If any significant core contributor has died, we've added a short obituary
484here.
233bba44 485
61174fb5 486=head1 Acknowledgements
d5dc7001 487
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488XXX Generate this with:
489
490 perl Porting/acknowledgements.pl v5.17.1..HEAD
29cf780c 491
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492=head1 Reporting Bugs
493
494If you find what you think is a bug, you might check the articles
52deee2e 495recently posted to the comp.lang.perl.misc newsgroup and the perl
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496bug database at http://rt.perl.org/perlbug/ . There may also be
497information at http://www.perl.org/ , the Perl Home Page.
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498
499If you believe you have an unreported bug, please run the L<perlbug>
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500program included with your release. Be sure to trim your bug down
501to a tiny but sufficient test case. Your bug report, along with the
502output of C<perl -V>, will be sent off to perlbug@perl.org to be
503analysed by the Perl porting team.
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504
505If the bug you are reporting has security implications, which make it
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506inappropriate to send to a publicly archived mailing list, then please send
507it to perl5-security-report@perl.org. This points to a closed subscription
508unarchived mailing list, which includes
509all the core committers, who will be able
510to help assess the impact of issues, figure out a resolution, and help
511co-ordinate the release of patches to mitigate or fix the problem across all
512platforms on which Perl is supported. Please only use this address for
513security issues in the Perl core, not for modules independently
514distributed on CPAN.
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515
516=head1 SEE ALSO
517
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518The F<Changes> file for an explanation of how to view exhaustive details
519on what changed.
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520
521The F<INSTALL> file for how to build Perl.
522
523The F<README> file for general stuff.
524
525The F<Artistic> and F<Copying> files for copyright information.
526
527=cut