This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
This patch with tests resolves CPAN RT #40727. The issue is an infi-
[perl5.git] / pod / perldelta.pod
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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. ]
4c793fe3 7
ee0887a9 8perldelta - what is new for perl v5.13.6
4c793fe3 9
ee0887a9 10=head1 DESCRIPTION
0c692eed 11
ee0887a9
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12This document describes differences between the 5.13.5 release and
13the 5.13.6 release.
0c692eed 14
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15If you are upgrading from an earlier release such as 5.13.4, first read
16L<perl5135delta>, which describes differences between 5.13.4 and
175.13.5.
0c692eed 18
ee0887a9 19=head1 Notice
0c692eed 20
ee0887a9 21XXX Any important notices here
4c793fe3 22
ee0887a9 23=head1 Core Enhancements
85318b69 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.
85318b69 28
ee0887a9 29[ List each enhancement as a =head2 entry ]
85318b69 30
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31=head2 C<(?^...)> regex construct added to signify default modifiers
32
33A caret (also called a "cirumflex accent") C<"^"> immediately following
34a C<"(?"> in a regular expression now means that the subexpression is to
35not inherit the surrounding modifiers such as C</i>, but to revert to the
36Perl defaults. Any modifiers following the caret override the defaults.
37
38The stringification of regular expressions now uses this notation. The
39main purpose of this is to allow tests that rely on the stringification
40to not have to change when new modifiers are added. See
41L<perlre/Extended Patterns>.
42
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43=head2 C<"d">, C<"l">, and C<"u"> regex modifiers added
44
45These modifiers are currently only available within a C<(?...)> construct.
46
47The C<"l"> modifier says to compile the regular expression as if it were
48in the scope of C<use locale>, even if it is not.
49
50The C<"u"> modifier currently does nothing.
51
52The C<"d"> modifier is used in the scope of C<use locale> to compile the
53regular expression as if it were not in that scope.
54See L<perlre/(?dlupimsx-imsx)>.
55
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56=head2 C<\N{...}> now handles Unicode named character sequences
57
58Unicode has a number of named character sequences, in which particular sequences
59of code points are given names. C<\N{...}> now recognizes these.
60See L<charnames>.
61
62=head2 New function C<charnames::string_vianame()>
63
64This function is a run-time version of C<\N{...}>, returning the string
65of characters whose Unicode name is its parameter. It can handle
66Unicode named character sequences, whereas the pre-existing
67C<charnames::vianame()> cannot, as the latter returns a single code
68point.
69See L<charnames>.
70
ee0887a9 71=head1 Security
85318b69 72
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73XXX Any security-related notices go here. In particular, any security
74vulnerabilities closed should be noted here rather than in the
75L</Selected Bug Fixes> section.
85318b69 76
ee0887a9 77[ List each security issue as a =head2 entry ]
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78
79=head1 Incompatible Changes
80
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81=head2 Stringification of regexes has changed
82
83Default regular expression modifiers are now notated by using
84C<(?^...)>. Code relying on the old stringification will fail. The
85purpose of this is so that when new modifiers are added, such code will
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86not have to change (after this one time), as the stringification will
87automatically incorporate the new modifiers.
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88
89Code that needs to work properly with both old- and new-style regexes
e23837fb 90can avoid the whole issue by using (for Perls since 5.9.5):
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91
92 use re qw(regexp_pattern);
93 my ($pat, $mods) = regexp_pattern($re_ref);
94
95where C<$re_ref> is a reference to a compiled regular expression. Upon
96return, C<$mods> will be a string containing all the non-default
97modifiers used when the regular expression was compiled, and C<$pattern>
98the actual pattern.
99
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100If the actual stringification is important, or older Perls need to be
101supported, you can use something like the following:
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102
103 # Accept both old and new-style stringification
104 my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? '^' : '-xism';
44428a46 105
fb85c044 106And then use C<$modifiers> instead of C<-xism>.
44428a46 107
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108=head2 Regular expressions retain their localeness when interpolated
109
110Regular expressions compiled under C<"use locale"> now retain this when
111interpolated into a new regular expression compiled outside a
112C<"use locale">, and vice-versa.
113
114Previously, a regular expression interpolated into another one inherited
115the localeness of the surrounding one, losing whatever state it
116originally had. This is considered a bug fix, but may trip up code that
117has come to rely on the incorrect behavior.
118
ee0887a9 119[ List each incompatible change as a =head2 entry ]
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120
121=head1 Deprecations
122
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123XXX Any deprecated features, syntax, modules etc. should be listed here.
124In particular, deprecated modules should be listed here even if they are
125listed as an updated module in the L</Modules and Pragmata> section.
85318b69 126
ee0887a9 127[ List each deprecation as a =head2 entry ]
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128
129=head1 Performance Enhancements
130
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131XXX Changes which enhance performance without changing behaviour go here. There
132may well be none in a stable release.
4c793fe3 133
ee0887a9 134[ List each enhancement as a =item entry ]
4c793fe3 135
ee0887a9 136=over 4
4c793fe3 137
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138=item *
139
ee0887a9 140XXX
e2babdfb 141
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142=back
143
144=head1 Modules and Pragmata
145
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146XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
147go here. If Module::CoreList is updated, generate an initial draft of the
148following sections using F<Porting/corelist-perldelta.pl>, which prints stub
149entries to STDOUT. Results can be pasted in place of the '=head2' entries
150below. A paragraph summary for important changes should then be added by hand.
151In an ideal world, dual-life modules would have a F<Changes> file that could be
152cribbed.
fc1418b7 153
ee0887a9 154[ Within each section, list entries as a =item entry ]
df91fef1 155
ee0887a9 156=head2 New Modules and Pragmata
ccb45ef4 157
ee0887a9 158=over 4
df91fef1 159
ee0887a9 160=item *
df91fef1 161
ee0887a9 162XXX
e2babdfb 163
ee0887a9 164=back
e2babdfb 165
ee0887a9 166=head2 Updated Modules and Pragmata
fc1418b7 167
ee0887a9 168=over 4
fc1418b7 169
ee0887a9 170=item *
e2babdfb 171
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172C<File::DosGlob> has been upgraded from version 1.02 to 1.03.
173
174It allows patterns containing literal parentheses (they no longer need to
175be escaped). On Windows, it no longer adds an extra F<./> to the file names
176returned when the pattern is a relative glob with a drive specification,
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177like F<c:*.pl>
178L<[perl #71712]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=71712>.
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179
180=item *
181
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182C<File::Find> has been upgraded from version 1.17 to 1.18.
183
184It improves handling of backslashes on Windows, so that paths such as
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185F<c:\dir\/file> are no longer generated
186L<[perl #71710]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=71710>.
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187
188=item *
189
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190C<NEXT> has been upgraded from version 0.64 to 0.65.
191
192=item *
193
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194C<PathTools> has been upgraded from version 3.31_01 to 3.33.
195
196=item *
197
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198C<sigtrap> has been upgraded from version 1.04 to 1.05.
199
200It no longer tries to modify read-only arguments when generating a
201backtrace
202L<[perl #72340]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=72340>.
203
204=item *
205
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206C<Unicode::Collate> has been upgraded from version 0.59 to 0.60
207
208=item *
209
1c2dcb3e 210C<Unicode::Normalize> has been upgraded from version 1.06 to 1.07
c9a84c8b 211
ee0887a9 212=back
c9a84c8b 213
ee0887a9 214=head2 Removed Modules and Pragmata
c9a84c8b 215
ee0887a9 216=over 4
4c793fe3 217
ee0887a9 218=item *
48c1efd2 219
ee0887a9 220XXX
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221
222=back
223
224=head1 Documentation
225
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226XXX Changes to files in F<pod/> go here. Consider grouping entries by
227file and be sure to link to the appropriate page, e.g. L<perlfunc>.
4c793fe3 228
ee0887a9 229=head2 New Documentation
4c793fe3 230
ee0887a9 231XXX Changes which create B<new> files in F<pod/> go here.
4c793fe3 232
ee0887a9 233=head3 L<XXX>
4c793fe3 234
ee0887a9 235XXX Description of the purpose of the new file here
4c793fe3 236
ee0887a9 237=head2 Changes to Existing Documentation
fc1418b7 238
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239XXX Changes which significantly change existing files in F<pod/> go here.
240However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
241section.
fc1418b7 242
ee0887a9 243=head3 L<XXX>
e2babdfb 244
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245=over 4
246
247=item *
248
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249The documentation for the C<SvTRUE> macro was simply wrong in stating that
250get-magic is not processed. It has been corrected.
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251
252=back
e2babdfb 253
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254=head1 Diagnostics
255
256The following additions or changes have been made to diagnostic output,
257including warnings and fatal error messages. For the complete list of
258diagnostic messages, see L<perldiag>.
259
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260XXX New or changed warnings emitted by the core's C<C> code go here. Also
261include any changes in L<perldiag> that reconcile it to the C<C> code.
4c793fe3 262
ee0887a9 263[ Within each section, list entries as a =item entry ]
4c793fe3 264
ee0887a9 265=head2 New Diagnostics
4c793fe3 266
ee0887a9 267XXX Newly added diagnostic messages go here
fc1418b7 268
ee0887a9 269=over 4
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270
271=item *
272
ee0887a9 273XXX
ebce6c40 274
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275=back
276
ee0887a9 277=head2 Changes to Existing Diagnostics
4c793fe3 278
ee0887a9 279XXX Changes (i.e. rewording) of diagnostic messages go here
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280
281=over 4
282
283=item *
284
ee0887a9 285XXX
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286
287=back
288
ee0887a9 289=head1 Utility Changes
4c793fe3 290
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291XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
292here. Most of these are built within the directories F<utils> and F<x2p>.
4c793fe3 293
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294[ List utility changes as a =head3 entry for each utility and =item
295entries for each change
296Use L<XXX> with program names to get proper documentation linking. ]
fc1418b7 297
ee0887a9 298=head3 L<XXX>
fc1418b7 299
ee0887a9 300=over 4
4c793fe3 301
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302=item *
303
ee0887a9 304XXX
44428a46 305
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306=back
307
ee0887a9 308=head1 Configuration and Compilation
4c793fe3 309
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310XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
311go here. Any other changes to the Perl build process should be listed here.
312However, any platform-specific changes should be listed in the
313L</Platform Support> section, instead.
4c793fe3 314
ee0887a9 315[ List changes as a =item entry ].
4c793fe3 316
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317=over 4
318
319=item *
320
ee0887a9 321XXX
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322
323=back
4c793fe3 324
ee0887a9 325=head1 Testing
0c692eed 326
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327XXX Any significant changes to the testing of a freshly built perl should be
328listed here. Changes which create B<new> files in F<t/> go here as do any
329large changes to the testing harness (e.g. when parallel testing was added).
330Changes to existing files in F<t/> aren't worth summarising, although the bugs
331that they represent may be covered elsewhere.
0c692eed 332
ee0887a9 333[ List each test improvement as a =item entry ]
0c692eed 334
ee0887a9 335=over 4
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336
337=item *
338
ee0887a9 339XXX
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340
341=back
342
ee0887a9 343=head1 Platform Support
4c793fe3 344
ee0887a9 345XXX Any changes to platform support should be listed in the sections below.
4c793fe3 346
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347[ Within the sections, list each platform as a =item entry with specific
348changes as paragraphs below it. ]
4c793fe3 349
ee0887a9 350=head2 New Platforms
0c692eed 351
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352XXX List any platforms that this version of perl compiles on, that previous
353versions did not. These will either be enabled by new files in the F<hints/>
354directories, or new subdirectories and F<README> files at the top level of the
355source tree.
0c692eed 356
ee0887a9 357=over 4
0c692eed 358
ee0887a9 359=item XXX-some-platform
0c692eed 360
ee0887a9 361XXX
0c692eed 362
ee0887a9 363=back
0c692eed 364
ee0887a9 365=head2 Discontinued Platforms
4c793fe3 366
ee0887a9 367XXX List any platforms that this version of perl no longer compiles on.
8ebb9810 368
ee0887a9 369=over 4
8ebb9810 370
ee0887a9 371=item XXX-some-platform
48c1efd2 372
ee0887a9 373XXX
48c1efd2 374
ee0887a9 375=back
44428a46 376
ee0887a9 377=head2 Platform-Specific Notes
44428a46 378
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379XXX List any changes for specific platforms. This could include configuration
380and compilation changes or changes in portability/compatibility. However,
381changes within modules for platforms should generally be listed in the
382L</Modules and Pragmata> section.
f4beb78f 383
ee0887a9 384=over 4
f4beb78f 385
ee0887a9 386=item XXX-some-platform
ccb45ef4 387
ee0887a9 388XXX
ccb45ef4 389
ee0887a9 390=back
85318b69 391
ee0887a9 392=head1 Internal Changes
85318b69 393
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394XXX Changes which affect the interface available to C<XS> code go here.
395Other significant internal changes for future core maintainers should
396be noted as well.
85318b69 397
ee0887a9 398[ List each test improvement as a =item entry ]
80b6a949 399
ee0887a9 400=over 4
80b6a949 401
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402=item *
403
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404See L</Regular expressions retain their localeness when interpolated>,
405above.
e2babdfb 406
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407=item *
408
409The C<sv_cmp_flags>, C<sv_cmp_locale_flags>, C<sv_eq_flags> and
410C<sv_collxfrm_flags> functions have been added. These are like their
411non-_flags counterparts, but allow one to specify whether get-magic is
412processed.
413
414The C<sv_cmp>, C<sv_cmp_locale>, C<sv_eq> and C<sv_collxfrm> functions have
415been replaced with wrappers around the new functions.
416
417=item *
418
419A new C<sv_2bool_flags> function has been added.
420
421This is like C<sv_2bool>, but it lets the calling code decide whether
422get-magic is handled. C<sv_2bool> is now a macro that calls the new
423function.
424
425=item *
426
427A new macro, C<SvTRUE_nomg>, has been added.
428
429This is like C<SvTRUE>, except that it does not process magic. It uses the
430new C<sv_2bool_flags> function.
431
432=item *
433
434C<sv_catsv_flags> no longer calls C<mg_get> on its second argument (the
435source string) if the flags passed to it do not include SV_GMAGIC. So it
436now matches what the documentation says it does.
437
ee0887a9 438=back
e2babdfb 439
ee0887a9 440=head1 Selected Bug Fixes
e2babdfb 441
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442XXX Important bug fixes in the core language are summarised here.
443Bug fixes in files in F<ext/> and F<lib/> are best summarised in
444L</Modules and Pragmata>.
e2babdfb 445
ee0887a9 446[ List each fix as a =item entry ]
346e4e56 447
ee0887a9 448=over 4
346e4e56 449
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450=item *
451
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452A regular expression match in the right-hand side of a global substitution
453(C<s///g>) that is in the same scope will no longer cause match variables
454to have the wrong values on subsequent iterations. This can happen when an
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455array or hash subscript is interpolated in the right-hand side, as in
456C<s|(.)|@a{ print($1), /./ }|g>
457L<[perl #19078]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=19078>.
458
459=item *
460
461Constant-folding used to cause
462
463 $text =~ ( 1 ? /phoo/ : /bear/)
464
465to turn into
466
467 $text =~ /phoo/
468
469at compile time. Now it correctly matches against C<$_>
470L<[perl #20444]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=20444>.
78846812 471
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472=item *
473
474Parsing Perl code (either with string C<eval> or by loading modules) from
475within a C<UNITCHECK> block no longer causes the interpreter to crash
476L<[perl #70614]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=70614>.
477
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478=item *
479
480When C<-d> is used on the shebang (C<#!>) line, the debugger now has access
481to the lines of the main program. In the past, this sometimes worked and
482sometimes did not, depending on what order things happened to be arranged
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483in memory
484L<[perl #71806]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=71806>.
5a9a79a4 485
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486=item *
487
488The C<y///> or C<tr///> operator now calls get-magic (e.g., the C<FETCH>
489method of a tie) on its left-hand side just once, not twice
490L<[perl #76814]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
491
492=item *
493
494String comparison (C<eq>, C<ne>, C<lt>, C<gt>, C<le>, C<ge> and
495C<cmp>) and logical not (C<not> and C<!>) operators no longer call magic
496(e.g., tie methods) twice on their operands
497L<[perl #76814]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
498
499This bug was introduced in an earlier 5.13 release, and does not affect
500perl 5.12.
501
502=item *
503
504When a tied (or other magic) variable is used as, or in, a regular
505expression, it no longer has its C<FETCH> method called twice
506L<[perl #76814]|http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
507
508This bug was introduced in an earlier 5.13 release, and does not affect
509perl 5.12.
510
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511=back
512
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513=head1 Known Problems
514
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515XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
516tests that had to be C<TODO>ed for the release would be noted here, unless
517they were specific to a particular platform (see below).
962fbe1d 518
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519This is a list of some significant unfixed bugs, which are regressions
520from either 5.XXX.XXX or 5.XXX.XXX.
962fbe1d 521
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522[ List each fix as a =item entry ]
523
524=over 4
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525
526=item *
527
ee0887a9 528XXX
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529
530=back
531
ee0887a9 532=head1 Obituary
4c793fe3 533
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534XXX If any significant core contributor has died, we've added a short obituary
535here.
0195fb5f 536
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537=head1 Errata
538
539=over 4
540
541=item *
542
543Fixed a typo in L<perl5135delta> regarding array slices and smart matching
544
545=back
546
ee0887a9 547=head1 Acknowledgements
0195fb5f 548
ee0887a9 549XXX The list of people to thank goes here.
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550
551=head1 Reporting Bugs
552
553If you find what you think is a bug, you might check the articles
554recently posted to the comp.lang.perl.misc newsgroup and the perl
555bug database at http://rt.perl.org/perlbug/ . There may also be
556information at http://www.perl.org/ , the Perl Home Page.
557
558If you believe you have an unreported bug, please run the B<perlbug>
559program included with your release. Be sure to trim your bug down
560to a tiny but sufficient test case. Your bug report, along with the
561output of C<perl -V>, will be sent off to perlbug@perl.org to be
562analysed by the Perl porting team.
563
564If the bug you are reporting has security implications, which make it
565inappropriate to send to a publicly archived mailing list, then please send
ee0887a9 566it to perl5-security-report@perl.org. This points to a closed subscription
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567unarchived mailing list, which includes all the core committers, who be able
568to help assess the impact of issues, figure out a resolution, and help
569co-ordinate the release of patches to mitigate or fix the problem across all
ee0887a9 570platforms on which Perl is supported. Please only use this address for
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571security issues in the Perl core, not for modules independently
572distributed on CPAN.
573
574=head1 SEE ALSO
575
576The F<Changes> file for an explanation of how to view exhaustive details
577on what changed.
578
579The F<INSTALL> file for how to build Perl.
580
581The F<README> file for general stuff.
582
583The F<Artistic> and F<Copying> files for copyright information.
584
585=cut