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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 v5.21.6
c68523cb 9
238894db 10=head1 DESCRIPTION
c68523cb 11
86372193 12This document describes differences between the 5.21.5 release and the 5.21.6
238894db 13release.
c68523cb 14
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15If you are upgrading from an earlier release such as 5.21.4, first read
16L<perl5215delta>, which describes differences between 5.21.4 and 5.21.5.
8435afd1 17
86372193 18=head1 Notice
5cfa0642 19
86372193 20XXX Any important notices here
4cad5dc8 21
86372193 22=head1 Core Enhancements
4cad5dc8 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.
a5591204 27
86372193 28[ List each enhancement as a =head2 entry ]
a5591204 29
518159a1
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30=head2 List form of pipe open implemented for Win32
31
32The list form of pipe:
33
34 open my $fh, "-|", "program", @arguments;
35
36is now implemented on Win32. It has the same limitations as C<system
37LIST> on Win32, since the Win32 API doesn't accept program arguments
38as a list.
39
86372193 40=head1 Security
a5591204 41
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42XXX Any security-related notices go here. In particular, any security
43vulnerabilities closed should be noted here rather than in the
44L</Selected Bug Fixes> section.
a5591204 45
86372193 46[ List each security issue as a =head2 entry ]
a5591204 47
86372193 48=head1 Incompatible Changes
a5591204 49
86372193 50XXX For a release on a stable branch, this section aspires to be:
a5591204 51
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52 There are no changes intentionally incompatible with 5.XXX.XXX
53 If any exist, they are bugs, and we request that you submit a
54 report. See L</Reporting Bugs> below.
b15c1b56 55
86372193 56[ List each incompatible change as a =head2 entry ]
b15c1b56 57
86372193 58=head1 Deprecations
bb8c7e27 59
86372193 60XXX Any deprecated features, syntax, modules etc. should be listed here.
bb8c7e27 61
86372193 62=head2 Module removals
bb8c7e27 63
86372193 64XXX Remove this section if inapplicable.
9a88d663 65
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66The following modules will be removed from the core distribution in a
67future release, and will at that time need to be installed from CPAN.
68Distributions on CPAN which require these modules will need to list them as
69prerequisites.
9a88d663 70
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71The core versions of these modules will now issue C<"deprecated">-category
72warnings to alert you to this fact. To silence these deprecation warnings,
73install the modules in question from CPAN.
5cfa0642 74
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75Note that these are (with rare exceptions) fine modules that you are encouraged
76to continue to use. Their disinclusion from core primarily hinges on their
77necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
78not usually on concerns over their design.
ba474e87 79
86372193 80=over
8435afd1 81
86372193 82=item XXX
d0ab07ee 83
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84XXX Note that deprecated modules should be listed here even if they are listed
85as an updated module in the L</Modules and Pragmata> section.
cc4d09e1 86
86372193 87=back
cc4d09e1 88
86372193 89[ List each other deprecation as a =head2 entry ]
8435afd1 90
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91=head2 Use of non-graphic characters in single-character variable names
92
93The syntax for single-character variable names is more lenient than
94for longer variable names, allowing the one-character name to be a
95punctuation character or even invisible (a non-graphic). Perl v5.20
96deprecated the ASCII-range controls as such a name. Now, all
97non-graphic characters that formerly were allowed are deprecated.
98The practical effect of this occurs only when not under C<S<"use
99utf8">>, and affects just the C1 controls (code points 0x80 through
1000xFF), NO-BREAK SPACE, and SOFT HYPHEN.
101
8c8d6154 102=head1 Performance Enhancements
5cfa0642 103
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104XXX Changes which enhance performance without changing behaviour go here.
105There may well be none in a stable release.
5cfa0642 106
86372193 107[ List each enhancement as a =item entry ]
8435afd1 108
86372193 109=over 4
5cfa0642 110
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111=item *
112
86372193 113XXX
5b306eef 114
86372193 115=back
357205d5 116
86372193 117=head1 Modules and Pragmata
357205d5 118
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119XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
120go here. If Module::CoreList is updated, generate an initial draft of the
121following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
122for important changes should then be added by hand. In an ideal world,
123dual-life modules would have a F<Changes> file that could be cribbed.
f704f251 124
86372193 125[ Within each section, list entries as a =item entry ]
f704f251 126
86372193 127=head2 New Modules and Pragmata
0cb3abac 128
86372193 129=over 4
0cb3abac 130
deec1830
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131=item *
132
86372193 133XXX
deec1830 134
8c8d6154 135=back
d0ab07ee 136
8c8d6154 137=head2 Updated Modules and Pragmata
d99849ae 138
39c4a6cf 139=over 4
d99849ae 140
ff433f2d
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141=item *
142
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143L<IO::Socket> has been upgraded from version 1.37 to 1.38.
144
145Document the limitations of the isconnected() method. [perl #123096]
cbfcbc14 146
86372193 147=back
f348c3d8 148
86372193 149=head2 Removed Modules and Pragmata
f348c3d8 150
86372193 151=over 4
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152
153=item *
154
86372193 155XXX
f348c3d8 156
86372193 157=back
7635ad4d 158
86372193 159=head1 Documentation
7635ad4d 160
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161XXX Changes to files in F<pod/> go here. Consider grouping entries by
162file and be sure to link to the appropriate page, e.g. L<perlfunc>.
7635ad4d 163
86372193 164=head2 New Documentation
f348c3d8 165
86372193 166XXX Changes which create B<new> files in F<pod/> go here.
f348c3d8 167
86372193 168=head3 L<XXX>
f4eedc6b 169
86372193 170XXX Description of the purpose of the new file here
f4eedc6b 171
86372193 172=head2 Changes to Existing Documentation
f4eedc6b 173
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174XXX Changes which significantly change existing files in F<pod/> go here.
175However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
176section.
f348c3d8 177
42327f06 178=head3 L<perldata/Identifier parsing>
f348c3d8 179
86372193 180=over 4
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181
182=item *
183
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184The syntax of single-character variable names has been brought
185up-to-date and more fully explained.
f348c3d8 186
86372193 187=back
f348c3d8 188
86372193 189=head1 Diagnostics
f348c3d8 190
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191The following additions or changes have been made to diagnostic output,
192including warnings and fatal error messages. For the complete list of
193diagnostic messages, see L<perldiag>.
f348c3d8 194
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195XXX New or changed warnings emitted by the core's C<C> code go here. Also
196include any changes in L<perldiag> that reconcile it to the C<C> code.
f348c3d8 197
86372193 198=head2 New Diagnostics
f348c3d8 199
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200XXX Newly added diagnostic messages go under here, separated into New Errors
201and New Warnings
f348c3d8 202
86372193 203=head3 New Errors
84d03adf 204
86372193 205=over 4
ff433f2d 206
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207=item *
208
86372193 209XXX L<message|perldiag/"message">
f348c3d8 210
86372193 211=back
f348c3d8 212
86372193 213=head3 New Warnings
f4eedc6b 214
86372193 215=over 4
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216
217=item *
218
4475d0d2 219L<Use of literal non-graphic characters in variable names is deprecated|perldiag/"Use of literal non-graphic characters in variable names is deprecated">
f348c3d8 220
86372193 221=back
0561e60b 222
86372193 223=head2 Changes to Existing Diagnostics
0561e60b 224
86372193 225XXX Changes (i.e. rewording) of diagnostic messages go here
0561e60b 226
86372193 227=over 4
4cd408ba 228
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229=item *
230
86372193 231XXX Describe change here
4cd408ba 232
86372193 233=back
40a81b59 234
86372193 235=head1 Utility Changes
f348c3d8 236
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237XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
238Most of these are built within the directory F<utils>.
f348c3d8 239
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240[ List utility changes as a =head2 entry for each utility and =item
241entries for each change
242Use L<XXX> with program names to get proper documentation linking. ]
f348c3d8 243
86372193 244=head2 L<XXX>
f348c3d8 245
86372193 246=over 4
f348c3d8
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247
248=item *
249
86372193 250XXX
40a81b59 251
13900f93 252=back
aac7f82f 253
86372193 254=head1 Configuration and Compilation
2a395b86 255
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256XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
257go here. Any other changes to the Perl build process should be listed here.
258However, any platform-specific changes should be listed in the
259L</Platform Support> section, instead.
8435afd1 260
86372193 261[ List changes as a =item entry ].
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262
263=over 4
2a395b86 264
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265=item *
266
c517e197 267F<Configure> with C<-Dmksymlinks> should now be faster. [perl #122002]
12d22d1f 268
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269=back
270
86372193 271=head1 Testing
2a395b86 272
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273XXX Any significant changes to the testing of a freshly built perl should be
274listed here. Changes which create B<new> files in F<t/> go here as do any
275large changes to the testing harness (e.g. when parallel testing was added).
276Changes to existing files in F<t/> aren't worth summarizing, although the bugs
277that they represent may be covered elsewhere.
2a395b86 278
86372193 279[ List each test improvement as a =item entry ]
5cfa0642 280
8c8d6154 281=over 4
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282
283=item *
284
86372193 285XXX
bb8c7e27 286
86372193 287=back
bb8c7e27 288
86372193 289=head1 Platform Support
bb8c7e27 290
86372193 291XXX Any changes to platform support should be listed in the sections below.
bb8c7e27 292
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293[ Within the sections, list each platform as a =item entry with specific
294changes as paragraphs below it. ]
2a395b86 295
86372193 296=head2 New Platforms
6d9b7c7c 297
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298XXX List any platforms that this version of perl compiles on, that previous
299versions did not. These will either be enabled by new files in the F<hints/>
300directories, or new subdirectories and F<README> files at the top level of the
301source tree.
363d3025 302
8c8d6154 303=over 4
334464b3 304
86372193 305=item XXX-some-platform
334464b3 306
86372193 307XXX
ef5a9509 308
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309=back
310
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311=head2 Discontinued Platforms
312
313XXX List any platforms that this version of perl no longer compiles on.
d72cd2eb 314
0346c3a9 315=over 4
375f5f06 316
86372193 317=item XXX-some-platform
2884baee 318
86372193 319XXX
6f1a844b 320
8c8d6154 321=back
549ea8d4 322
8c8d6154 323=head2 Platform-Specific Notes
aa292ef2 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.
329
8c8d6154 330=over 4
739e9bee 331
86372193 332=item XXX-some-platform
739e9bee 333
86372193 334XXX
b23b2fdb 335
8c8d6154 336=back
b23b2fdb 337
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338=head3 Win32
339
340=over 4
341
342=item *
343
344In the experimental C<:win32> layer, a crash in C<open> was fixed. Also
345opening C</dev/null>, which works the Win32 Perl's normal C<:unix> layer, was
346implemented for C<:win32>.
347L<[perl #122224]|https://rt.perl.org/Ticket/Display.html?id=122224>
348
349=back
350
8c8d6154 351=head1 Internal Changes
7d15b1a8 352
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353XXX Changes which affect the interface available to C<XS> code go here. Other
354significant internal changes for future core maintainers should be noted as
355well.
bbca64cf 356
86372193 357[ List each change as a =item entry ]
6ff8f256 358
86372193 359=over 4
28482d6c 360
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361=item *
362
86372193 363XXX
28a42920 364
8c8d6154 365=back
6ff8f256 366
8c8d6154 367=head1 Selected Bug Fixes
80cc3290 368
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369XXX Important bug fixes in the core language are summarized here. Bug fixes in
370files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
13dd5671 371
86372193 372[ List each fix as a =item entry ]
bdab7676 373
86372193 374=over 4
db98db4e 375
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376=item *
377
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378fchmod() and futimes() now set C<$!> when they fail due to being
379passed a closed file handle. [perl #122703]
bb8c7e27 380
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381=item *
382
383Perl now comes with a corrected Unicode 7.0 for the erratum issued on
384October 21, 2014 (see L<http://www.unicode.org/errata/#current_errata>),
385dealing with glyph shaping in Arabic.
386
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387=item *
388
389op_free() no longer crashes due to a stack overflow when freeing a
390deeply recursive op tree. [perl #108276]
391
53795ef8
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392=item *
393
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394scalarvoid() would crash due to a stack overflow when processing a
395deeply recursive op tree. [perl #108276]
396
397=item *
398
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399In Perl 5.20.0, C<$^N> accidentally had the internal UTF8 flag turned off
400if accessed from a code block within a regular expression, effectively
401UTF8-encoding the value. This has been fixed. [perl #123135]
402
86372193 403=back
bb8c7e27 404
86372193 405=head1 Known Problems
bb8c7e27 406
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407XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
408tests that had to be C<TODO>ed for the release would be noted here. Unfixed
409platform specific bugs also go here.
bb8c7e27 410
86372193 411[ List each fix as a =item entry ]
bb8c7e27 412
86372193 413=over 4
bb8c7e27 414
74f9f9ed
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415=item *
416
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417Starting in 5.21.6, accessing L<perlapi/CvPADLIST> in an XSUB is forbidden.
418CvPADLIST has be reused for a different internal purpose for XSUBs. Guard all
419CvPADLIST expressions with C<CvISXSUB()> if your code doesn't already block
420XSUB CV*s from going through optree CV* expecting code.
28a42920 421
86372193 422=back
28a42920 423
86372193 424=head1 Errata From Previous Releases
28a42920 425
86372193 426=over 4
28a42920
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427
428=item *
429
86372193
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430XXX Add anything here that we forgot to add, or were mistaken about, in
431the perldelta of a previous release.
28a42920 432
8c8d6154 433=back
3a085d00 434
86372193 435=head1 Obituary
01d42a22 436
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437XXX If any significant core contributor has died, we've added a short obituary
438here.
01d42a22 439
86372193 440=head1 Acknowledgements
01d42a22 441
86372193 442XXX Generate this with:
01d42a22 443
86372193 444 perl Porting/acknowledgements.pl v5.21.5..HEAD
f5b73711 445
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446=head1 Reporting Bugs
447
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448If you find what you think is a bug, you might check the articles recently
449posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 450https://rt.perl.org/ . There may also be information at
7ef8b31d 451http://www.perl.org/ , the Perl Home Page.
44691e6f 452
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453If you believe you have an unreported bug, please run the L<perlbug> program
454included with your release. Be sure to trim your bug down to a tiny but
455sufficient test case. Your bug report, along with the output of C<perl -V>,
456will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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457
458If the bug you are reporting has security implications, which make it
e08634c5
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459inappropriate to send to a publicly archived mailing list, then please send it
460to perl5-security-report@perl.org. This points to a closed subscription
461unarchived mailing list, which includes all the core committers, who will be
462able to help assess the impact of issues, figure out a resolution, and help
f9001595 463co-ordinate the release of patches to mitigate or fix the problem across all
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464platforms on which Perl is supported. Please only use this address for
465security issues in the Perl core, not for modules independently distributed on
466CPAN.
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467
468=head1 SEE ALSO
469
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470The F<Changes> file for an explanation of how to view exhaustive details on
471what changed.
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472
473The F<INSTALL> file for how to build Perl.
474
475The F<README> file for general stuff.
476
477The F<Artistic> and F<Copying> files for copyright information.
478
479=cut