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Correct typo reported by Hauke D. (RT #41359)
[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 XXX needs
6to be processed before release. ]
7
8perldelta - what is new for perl v5.21.4
c68523cb 9
238894db 10=head1 DESCRIPTION
c68523cb 11
39c4a6cf 12This document describes differences between the 5.21.3 release and the 5.21.4
238894db 13release.
c68523cb 14
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15If you are upgrading from an earlier release such as 5.21.2, first read
16L<perl5213delta>, which describes differences between 5.21.2 and 5.21.3.
7065301c 17
39c4a6cf 18=head1 Notice
7e957246 19
39c4a6cf 20XXX Any important notices here
7e957246 21
39c4a6cf 22=head1 Core Enhancements
f88f10f5 23
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24XXX New core language features go here. Summarize user-visible core language
25enhancements. Particularly prominent performance optimisations could go
26here, but most should go in the L</Performance Enhancements> section.
21f3b41e 27
39c4a6cf 28[ List each enhancement as a =head2 entry ]
f88f10f5 29
0346c3a9 30=head1 Security
7e957246 31
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32XXX Any security-related notices go here. In particular, any security
33vulnerabilities closed should be noted here rather than in the
34L</Selected Bug Fixes> section.
13900f93 35
39c4a6cf 36[ List each security issue as a =head2 entry ]
8bdb3f93 37
13900f93 38=head1 Incompatible Changes
8bdb3f93 39
39c4a6cf 40XXX For a release on a stable branch, this section aspires to be:
1178d2cf 41
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42 There are no changes intentionally incompatible with 5.XXX.XXX
43 If any exist, they are bugs, and we request that you submit a
44 report. See L</Reporting Bugs> below.
1178d2cf 45
39c4a6cf 46[ List each incompatible change as a =head2 entry ]
f6f3144e 47
39c4a6cf 48=head1 Deprecations
7065301c 49
39c4a6cf 50XXX Any deprecated features, syntax, modules etc. should be listed here.
7065301c 51
39c4a6cf 52=head2 Module removals
b3e82ed1 53
39c4a6cf 54XXX Remove this section if inapplicable.
ca58223b 55
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56The following modules will be removed from the core distribution in a
57future release, and will at that time need to be installed from CPAN.
58Distributions on CPAN which require these modules will need to list them as
59prerequisites.
ca58223b 60
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61The core versions of these modules will now issue C<"deprecated">-category
62warnings to alert you to this fact. To silence these deprecation warnings,
63install the modules in question from CPAN.
23b03637 64
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65Note that these are (with rare exceptions) fine modules that you are encouraged
66to continue to use. Their disinclusion from core primarily hinges on their
67necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
68not usually on concerns over their design.
23b03637 69
39c4a6cf 70=over
85e8fb10 71
39c4a6cf 72=item XXX
85e8fb10 73
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74XXX Note that deprecated modules should be listed here even if they are listed
75as an updated module in the L</Modules and Pragmata> section.
134f90c2 76
39c4a6cf 77=back
134f90c2 78
39c4a6cf 79[ List each other deprecation as a =head2 entry ]
ff433f2d 80
39c4a6cf 81=head1 Performance Enhancements
ff433f2d 82
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83XXX Changes which enhance performance without changing behaviour go here.
84There may well be none in a stable release.
134f90c2 85
39c4a6cf 86[ List each enhancement as a =item entry ]
134f90c2 87
39c4a6cf 88=over 4
7d19f6a1 89
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90=item *
91
39c4a6cf 92XXX
55e8b286 93
39c4a6cf 94=back
55e8b286 95
39c4a6cf 96=head1 Modules and Pragmata
d99849ae 97
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98XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
99go here. If Module::CoreList is updated, generate an initial draft of the
100following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
101for important changes should then be added by hand. In an ideal world,
102dual-life modules would have a F<Changes> file that could be cribbed.
d99849ae 103
39c4a6cf 104[ Within each section, list entries as a =item entry ]
ff433f2d 105
39c4a6cf 106=head2 New Modules and Pragmata
ff433f2d 107
39c4a6cf 108=over 4
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109
110=item *
111
39c4a6cf 112XXX
0bb39c26 113
39c4a6cf 114=back
0bb39c26 115
39c4a6cf 116=head2 Updated Modules and Pragmata
9c97a342 117
39c4a6cf 118=over 4
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119
120=item *
121
39c4a6cf 122L<XXX> has been upgraded from version A.xx to B.yy.
6ab3666b 123
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124=item *
125
126L<File::Find> has been upgraded from version 1.27 to 1.28.
39091b75 127
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128C<find()> and C<finddepth()> will now warn if passed inappropriate or
129misspelled options.
130
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131=item *
132
133L<B::Concise> has been upgraded from version 0.992 to 0.993.
134
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135
136=item *
137
138L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280219.
139[perl #122675].
140
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141=item *
142
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143L<ExtUtils::Manifest> has been upgraded from version 1.65 to 1.66.
144[perl #122415].
145
146=item *
147
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148L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
149
150=item *
151
152L<Module::CoreList> has been upgraded from version 5.021003 to 5.021004.
153
154=item *
155
156L<POSIX> has been upgraded from version 1.42 to 1.43.
157
158=item *
159
160L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
161
162=item *
163
164L<constant> has been upgraded from version 1.31 to 1.32.
165
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166It now accepts fully-qualified constant names, allowing constants to be
167defined in packages other than the caller.
168
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169=item *
170
171L<threads> has been upgraded from version 1.95 to 1.96.
172
39c4a6cf 173=back
9c97a342 174
39c4a6cf 175=head2 Removed Modules and Pragmata
d99849ae 176
39c4a6cf 177=over 4
d99849ae 178
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179=item *
180
39c4a6cf 181XXX
ff433f2d 182
13900f93 183=back
aac7f82f 184
13900f93 185=head1 Documentation
aac7f82f 186
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187XXX Changes to files in F<pod/> go here. Consider grouping entries by
188file and be sure to link to the appropriate page, e.g. L<perlfunc>.
6d9b7c7c 189
39c4a6cf 190=head2 New Documentation
2a395b86 191
39c4a6cf 192XXX Changes which create B<new> files in F<pod/> go here.
2a395b86 193
39c4a6cf 194=head3 L<XXX>
2a395b86 195
39c4a6cf 196XXX Description of the purpose of the new file here
2a395b86 197
39c4a6cf 198=head2 Changes to Existing Documentation
2a395b86 199
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200XXX Changes which significantly change existing files in F<pod/> go here.
201However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
202section.
203
204=head3 L<XXX>
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205
206=over 4
207
208=item *
209
39c4a6cf 210XXX Description of the change here
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211
212=back
213
39c4a6cf 214=head1 Diagnostics
2a395b86 215
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216The following additions or changes have been made to diagnostic output,
217including warnings and fatal error messages. For the complete list of
218diagnostic messages, see L<perldiag>.
2a395b86 219
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220XXX New or changed warnings emitted by the core's C<C> code go here. Also
221include any changes in L<perldiag> that reconcile it to the C<C> code.
2a395b86 222
39c4a6cf 223=head2 New Diagnostics
0f4a583b 224
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225XXX Newly added diagnostic messages go under here, separated into New Errors
226and New Warnings
2a395b86 227
39c4a6cf 228=head3 New Errors
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229
230=over 4
231
232=item *
233
39c4a6cf 234XXX L<message|perldiag/"message">
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235
236=back
237
39c4a6cf 238=head3 New Warnings
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239
240=over 4
241
242=item *
243
39c4a6cf 244XXX L<message|perldiag/"message">
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245
246=back
6d9b7c7c 247
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248=head2 Changes to Existing Diagnostics
249
250XXX Changes (i.e. rewording) of diagnostic messages go here
7f55cec0 251
13900f93 252=over 4
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253
254=item *
255
39c4a6cf 256XXX Describe change here
aac7f82f 257
13900f93 258=back
aac7f82f 259
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260=head2 Diagnostic Removals
261
262=over 4
263
264=item *
265
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266"Constant is not a FOO reference"
267
268Compile-time checking of constant dereferencing (e.g.,
269C<< my_constant->() >>) has been removed, since it was not taking
270overloading into account. [perl #69456] [perl #122607]
271
272=item *
273
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274The warning "Ambiguous use of -foo resolved as -&foo()" has been removed.
275There is actually no ambiguity here, and this impedes the use of negated
276constants; e.g., C<-Inf>.
277
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278=item *
279
280The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
281could get confused in the scope of C<use utf8> if C<Class> were a constant
282whose value contained Latin-1 characters.
283
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284=back
285
39c4a6cf 286=head1 Utility Changes
091fed7c 287
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288XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
289Most of these are built within the directory F<utils>.
902c1f75 290
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291[ List utility changes as a =head2 entry for each utility and =item
292entries for each change
293Use L<XXX> with program names to get proper documentation linking. ]
2901561d 294
39c4a6cf 295=head2 L<XXX>
4594cf53 296
13900f93 297=over 4
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298
299=item *
300
39c4a6cf 301XXX
a1d26ccd 302
39c4a6cf 303=back
a1d26ccd 304
39c4a6cf 305=head1 Configuration and Compilation
7065301c 306
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307XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
308go here. Any other changes to the Perl build process should be listed here.
309However, any platform-specific changes should be listed in the
310L</Platform Support> section, instead.
58f25ac1 311
39c4a6cf 312[ List changes as a =item entry ].
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313
314=over 4
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315
316=item *
317
39c4a6cf 318XXX
a5873648 319
39c4a6cf 320=back
a5873648 321
39c4a6cf 322=head1 Testing
a5873648 323
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324XXX Any significant changes to the testing of a freshly built perl should be
325listed here. Changes which create B<new> files in F<t/> go here as do any
326large changes to the testing harness (e.g. when parallel testing was added).
327Changes to existing files in F<t/> aren't worth summarizing, although the bugs
328that they represent may be covered elsewhere.
a5873648 329
39c4a6cf 330[ List each test improvement as a =item entry ]
a5873648 331
39c4a6cf 332=over 4
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333
334=item *
335
39c4a6cf 336XXX
a5873648 337
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338=back
339
39c4a6cf 340=head1 Platform Support
b10906fb 341
39c4a6cf 342XXX Any changes to platform support should be listed in the sections below.
b10906fb 343
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344[ Within the sections, list each platform as a =item entry with specific
345changes as paragraphs below it. ]
b10906fb 346
39c4a6cf 347=head2 New Platforms
b10906fb 348
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349XXX List any platforms that this version of perl compiles on, that previous
350versions did not. These will either be enabled by new files in the F<hints/>
351directories, or new subdirectories and F<README> files at the top level of the
352source tree.
13900f93 353
7065301c 354=over 4
24a38d90 355
39c4a6cf 356=item XXX-some-platform
24a38d90 357
39c4a6cf 358XXX
bb076206 359
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360=back
361
39c4a6cf 362=head2 Discontinued Platforms
097675bf 363
39c4a6cf 364XXX List any platforms that this version of perl no longer compiles on.
b3211734 365
6e97d65d 366=over 4
b3211734 367
39c4a6cf 368=item XXX-some-platform
7065301c 369
39c4a6cf 370XXX
13900f93 371
39c4a6cf 372=back
7d0ccdba 373
39c4a6cf 374=head2 Platform-Specific Notes
7d0ccdba 375
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376XXX List any changes for specific platforms. This could include configuration
377and compilation changes or changes in portability/compatibility. However,
378changes within modules for platforms should generally be listed in the
379L</Modules and Pragmata> section.
6e97d65d 380
39c4a6cf 381=over 4
6e97d65d 382
39c4a6cf 383=item XXX-some-platform
6e97d65d 384
39c4a6cf 385XXX
7d0ccdba 386
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387=back
388
389=head1 Internal Changes
390
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391XXX Changes which affect the interface available to C<XS> code go here. Other
392significant internal changes for future core maintainers should be noted as
393well.
c9fcb674 394
39c4a6cf 395[ List each change as a =item entry ]
a835cd47 396
39c4a6cf 397=over 4
c1284011 398
7d15b1a8 399XXX
1c43698b 400
6d9b7c7c 401=back
c1284011 402
6d9b7c7c 403=head1 Selected Bug Fixes
375f5f06 404
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405XXX Important bug fixes in the core language are summarized here. Bug fixes in
406files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
407
408[ List each fix as a =item entry ]
409
0346c3a9 410=over 4
375f5f06 411
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412=item *
413
39c4a6cf 414XXX
2884baee 415
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416=item *
417
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418Constant dereferencing now works correctly for typeglob constants.
419Previously the glob was stringified and its name looked up. Now the glob
420itself is used. [perl #69456]
421
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422=item *
423
424When parsing a funny character ($ @ % &) followed by braces, the parser no
425longer tries to guess whether it is a block or a hash constructor (causing
426a syntax error when it guesses the latter), since it can only be a block.
427
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428=item *
429
430C<undef $reference> now frees the referent immediately, instead of hanging
431on to it until the next statement. [perl #122556]
432
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433=item *
434
435Various cases where the name of a sub is used (autoload, overloading, error
436messages) used to crash for lexical subs, but have been fixed.
437
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438=item *
439
440Bareword lookup now tries to avoid vivifying packages if it turns out the
441bareword is not going to be a subroutine name.
442
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443=item *
444
445Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer
446deletes any subroutine named C<__ANON__> in the current package. Not only
447was C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug
448goes back to perl 5.8.0.
449
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450=item *
451
452Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out
453constants of the same name declared by C<use constant>. This bug was
454introduced in perl 5.10.0.
455
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456=item *
457
458Under some conditions a warning raised in compilation of regular
459expression patterns could be displayed multiple times. This is now
460fixed.
461
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462=item *
463
464C<qr/[\N{named sequence}]/> now works properly in many instances. Some
465names known to C<\N{...}> refer to a sequence of multiple characters,
466instead of the usual single character. Bracketed character classes
467generally only match single characters, but now special handling has
468been added so that they can match named sequences, but not if the class
469is inverted or the sequence is specified as the beginning or end of a
470range. In these cases, the only behavior change from before is a slight
471rewording of the fatal error message given when this class is part of a
472C<?[...])> construct. When the C<[...]> stands alone, the same
473non-fatal warning as before is raised, and only the first character in
474the sequence is used, again just as before.
475
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476=item *
477
478Tainted constants evaluated at compile time no longer cause unrelated
479statements to become tainted. [perl #122669]
480
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481=item *
482
483C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0",
484was not giving the handle the right reference count, so a double free could
485happen.
486
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487=item *
488
489When deciding that a bareword was a method name, the parser would get
490confused if an "our" sub with the same name existed, and look up the method
491in the package of the "our" sub, instead of the package of the invocant.
492
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493=item *
494
495The parser no longer gets confused by C<\U=> within a double-quoted string.
496It used to roduce a syntax error, but now compiles it correctly.
497[perl #80368]
498
39c4a6cf 499=back
b756670b 500
39c4a6cf 501=head1 Known Problems
b756670b 502
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503XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
504tests that had to be C<TODO>ed for the release would be noted here. Unfixed
505platform specific bugs also go here.
e917e94e 506
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507[ List each fix as a =item entry ]
508
509=over 4
e917e94e 510
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511=item *
512
39c4a6cf 513XXX
26dd5fd6 514
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515=back
516
39c4a6cf 517=head1 Errata From Previous Releases
e831f11a 518
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519=over 4
520
521=item *
ff433f2d 522
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523XXX Add anything here that we forgot to add, or were mistaken about, in
524the perldelta of a previous release.
ff433f2d 525
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526=back
527
528=head1 Obituary
ff433f2d 529
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530XXX If any significant core contributor has died, we've added a short obituary
531here.
ff433f2d 532
39c4a6cf 533=head1 Acknowledgements
ff433f2d 534
39c4a6cf 535XXX Generate this with:
e831f11a 536
39c4a6cf 537 perl Porting/acknowledgements.pl v5.21.3..HEAD
f5b73711 538
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539=head1 Reporting Bugs
540
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541If you find what you think is a bug, you might check the articles recently
542posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 543https://rt.perl.org/ . There may also be information at
7ef8b31d 544http://www.perl.org/ , the Perl Home Page.
44691e6f 545
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546If you believe you have an unreported bug, please run the L<perlbug> program
547included with your release. Be sure to trim your bug down to a tiny but
548sufficient test case. Your bug report, along with the output of C<perl -V>,
549will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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550
551If the bug you are reporting has security implications, which make it
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552inappropriate to send to a publicly archived mailing list, then please send it
553to perl5-security-report@perl.org. This points to a closed subscription
554unarchived mailing list, which includes all the core committers, who will be
555able to help assess the impact of issues, figure out a resolution, and help
f9001595 556co-ordinate the release of patches to mitigate or fix the problem across all
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557platforms on which Perl is supported. Please only use this address for
558security issues in the Perl core, not for modules independently distributed on
559CPAN.
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560
561=head1 SEE ALSO
562
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563The F<Changes> file for an explanation of how to view exhaustive details on
564what changed.
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565
566The F<INSTALL> file for how to build Perl.
567
568The F<README> file for general stuff.
569
570The F<Artistic> and F<Copying> files for copyright information.
571
572=cut