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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. ]
417a992d 7
4eabcf70 8perldelta - what is new for perl v5.17.3
e128ab2c 9
4eabcf70 10=head1 DESCRIPTION
6db9054f 11
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12This document describes differences between the 5.17.2 release and
13the 5.17.3 release.
6db9054f 14
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15If you are upgrading from an earlier release such as 5.17.1, first read
16L<perl5172delta>, which describes differences between 5.17.1 and
175.17.2.
ef7131e9 18
4eabcf70 19=head1 Notice
ff3f295c 20
4eabcf70 21XXX Any important notices here
95c6c5c5 22
4eabcf70 23=head1 Core Enhancements
95c6c5c5 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.
4c77591b 28
4eabcf70 29[ List each enhancement as a =head2 entry ]
c506fc7e 30
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31=head2 Computed Labels
32
33The loop controls C<next>, C<last> and C<redo>, and the special C<dump>
34operator, now allow arbitrary expressions to be used to compute labels at
35run time. Previously, any argument that was not a constant was treated as
36the empty string.
37
4eabcf70 38=head1 Security
36ab1671 39
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40XXX Any security-related notices go here. In particular, any security
41vulnerabilities closed should be noted here rather than in the
42L</Selected Bug Fixes> section.
36ab1671 43
4eabcf70 44[ List each security issue as a =head2 entry ]
36ab1671 45
4eabcf70 46=head1 Incompatible Changes
df2c1bb8 47
613c63b4 48[ List each incompatible change as a =head2 entry ]
df2c1bb8 49
613c63b4 50=head2 C<$ENV{foo} = undef> deletes value from environ, like C<delete $ENV{foo}>
df2c1bb8 51
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52This facilitates use of C<local()> with C<%ENV> entries. In previous
53versions of Perl, C<undef> was converted to the empty string.
54
55=head2 Defined values stored in environment are forced to byte strings
56
57A value stored in an environment variable has always been stringified. In
58this release, it is converted to be only a byte string. First, it is forced
59to be a only a string. Then if the string is utf8 and the equivalent of
60C<utf8::downgrade> works, that result is used; otherwise, the equivalent of
61C<utf8::encode> is used, and a warning is issued about wide characters
62(L</Diagnostics>).
7ab2ea42 63
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64=head2 C<given> now aliases the global $_
65
66Instead of assigning to an implicit lexical $_, C<given> now makes the
67global $_ an alias for its argument, just like C<foreach>. However, it
68still uses lexical $_ if there is lexical $_ in scope (again, just like
69C<foreach>).
70
4eabcf70 71=head1 Deprecations
7ab2ea42 72
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73XXX Any deprecated features, syntax, modules etc. should be listed here.
74In particular, deprecated modules should be listed here even if they are
75listed as an updated module in the L</Modules and Pragmata> section.
7ab2ea42 76
4eabcf70 77[ List each deprecation as a =head2 entry ]
7ab2ea42 78
4eabcf70 79=head1 Performance Enhancements
3be135d8 80
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81XXX Changes which enhance performance without changing behaviour go here. There
82may well be none in a stable release.
3be135d8 83
4eabcf70 84[ List each enhancement as a =item entry ]
6db9054f 85
4eabcf70 86=over 4
6db9054f 87
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88=item *
89
4eabcf70 90XXX
7ca04d94 91
e96e0834 92=back
c506fc7e 93
4eabcf70 94=head1 Modules and Pragmata
95c6c5c5 95
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96XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
97go here. If Module::CoreList is updated, generate an initial draft of the
98following sections using F<Porting/corelist-perldelta.pl>, which prints stub
99entries to STDOUT. Results can be pasted in place of the '=head2' entries
100below. A paragraph summary for important changes should then be added by hand.
101In an ideal world, dual-life modules would have a F<Changes> file that could be
102cribbed.
95c6c5c5 103
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104[ Within each section, list entries as a =item entry ]
105
106=head2 New Modules and Pragmata
95c6c5c5 107
e96e0834 108=over 4
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109
110=item *
111
4eabcf70 112XXX
95c6c5c5 113
e96e0834 114=back
95c6c5c5 115
4eabcf70 116=head2 Updated Modules and Pragmata
95c6c5c5 117
e96e0834 118=over 4
95c6c5c5 119
95c6c5c5
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120=item *
121
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122L<B> has been upgraded from version 1.36 to version 1.37. All C<CVf_*> and
123C<GVf_*> and more SV-related flag values are now provided as constants in
124the C<B::> namespace and available for export. The default export list has
125not changed.
b8a55fe7 126
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127=item *
128
129L<B::Deparse> has been upgraded from version 1.15 to 1.16. It now deparses
130loop controls with the correct precedence.
131
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132=item *
133
134L<Storable> has been upgraded from version 2.37 to 2.38. It can now freeze
135and thaw vstrings correctly. This causes a slight incompatible change in
136the storage format, so the format version has increased to 2.9.
137
e96e0834 138=back
95c6c5c5 139
4eabcf70 140=head2 Removed Modules and Pragmata
95c6c5c5 141
e96e0834 142=over 4
95c6c5c5 143
95c6c5c5
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144=item *
145
4eabcf70 146XXX
4f85bc45 147
4eabcf70 148=back
72267260 149
4eabcf70 150=head1 Documentation
72267260 151
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152XXX Changes to files in F<pod/> go here. Consider grouping entries by
153file and be sure to link to the appropriate page, e.g. L<perlfunc>.
4f85bc45 154
4eabcf70 155=head2 New Documentation
7d101ed1 156
4eabcf70 157XXX Changes which create B<new> files in F<pod/> go here.
e013ada0 158
4eabcf70 159=head3 L<XXX>
4f85bc45 160
4eabcf70 161XXX Description of the purpose of the new file here
e013ada0 162
4eabcf70 163=head2 Changes to Existing Documentation
95c6c5c5 164
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165XXX Changes which significantly change existing files in F<pod/> go here.
166However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
167section.
95c6c5c5 168
be28af6e 169=head3 L<perlfunc>, L<perlop>
95c6c5c5 170
e96e0834 171=over 4
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172
173=item *
174
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175Loop control verbs (C<dump>, C<goto>, C<next>, C<last> and C<redo>) have
176always had the same precedence as assignment operators, but this was never
177documented until now.
95c6c5c5 178
e96e0834 179=back
95c6c5c5 180
4eabcf70 181=head1 Diagnostics
05c8f9ed 182
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183The following additions or changes have been made to diagnostic output,
184including warnings and fatal error messages. For the complete list of
185diagnostic messages, see L<perldiag>.
ceb0881c 186
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187XXX New or changed warnings emitted by the core's C<C> code go here. Also
188include any changes in L<perldiag> that reconcile it to the C<C> code.
0998713f 189
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190[ Within each section, list entries as a =item entry that links to perldiag,
191 e.g.
112b6866 192
4eabcf70 193 =item *
112b6866 194
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195 L<Invalid version object|perldiag/"Invalid version object">
196]
42d72fc5 197
4eabcf70 198=head2 New Diagnostics
42d72fc5 199
4eabcf70 200XXX Newly added diagnostic messages go here
8e125188 201
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202=over 4
203
204=item *
205
206Attempts to put wide characters into environment variables via %ENV provoke
207the warning "Wide character in setenv".
208
209=back
210
4eabcf70 211=head3 New Errors
8e125188 212
e96e0834 213=over 4
e128ab2c 214
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215=item *
216
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217L<Unterminated delimiter for here document|perldiag/"Unterminated delimiter for here document">
218
219This message now occurs when a here document label has an initial quotation mark but the final quotation mark is missing.
220
221This replaces a bogus and misleading error message about not finding the
222label itself [perl #114104].
16e4fcbf 223
4eabcf70 224=back
e2f0c3bb 225
4eabcf70 226=head3 New Warnings
90519d0f 227
4eabcf70 228=over 4
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229
230=item *
231
4eabcf70 232XXX L<message|perldiag/"message">
90519d0f 233
61174fb5 234=back
422287bf 235
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236=head2 Changes to Existing Diagnostics
237
238XXX Changes (i.e. rewording) of diagnostic messages go here
2de6ba8d 239
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240=over 4
241
242=item *
243
4eabcf70 244XXX Describe change here
e128ab2c 245
4eabcf70 246=back
8b1adbab 247
4eabcf70 248=head1 Utility Changes
8b1adbab 249
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250XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
251here. Most of these are built within the directories F<utils> and F<x2p>.
83f29afa 252
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253[ List utility changes as a =head3 entry for each utility and =item
254entries for each change
255Use L<XXX> with program names to get proper documentation linking. ]
83f29afa 256
4eabcf70 257=head3 L<XXX>
0938f143 258
4eabcf70 259=over 4
0938f143 260
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261=item *
262
4eabcf70 263XXX
7a251f7a 264
4eabcf70 265=back
7a251f7a 266
4eabcf70 267=head1 Configuration and Compilation
21247d85 268
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269XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
270go here. Any other changes to the Perl build process should be listed here.
271However, any platform-specific changes should be listed in the
272L</Platform Support> section, instead.
21247d85 273
4eabcf70 274[ List changes as a =item entry ].
2e4f8b82 275
4eabcf70 276=over 4
c95d4104 277
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278=item *
279
4eabcf70 280XXX
788505db 281
4eabcf70 282=back
2c2b9cf4 283
4eabcf70 284=head1 Testing
3cd56aaa 285
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286XXX Any significant changes to the testing of a freshly built perl should be
287listed here. Changes which create B<new> files in F<t/> go here as do any
288large changes to the testing harness (e.g. when parallel testing was added).
289Changes to existing files in F<t/> aren't worth summarising, although the bugs
290that they represent may be covered elsewhere.
3cd56aaa 291
4eabcf70 292[ List each test improvement as a =item entry ]
3cd56aaa 293
4eabcf70 294=over 4
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295
296=item *
297
4eabcf70 298XXX
3cd56aaa 299
4eabcf70 300=back
3cd56aaa 301
4eabcf70 302=head1 Platform Support
3cd56aaa 303
4eabcf70 304XXX Any changes to platform support should be listed in the sections below.
3cd56aaa 305
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306[ Within the sections, list each platform as a =item entry with specific
307changes as paragraphs below it. ]
3cd56aaa 308
4eabcf70 309=head2 New Platforms
3cd56aaa 310
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311XXX List any platforms that this version of perl compiles on, that previous
312versions did not. These will either be enabled by new files in the F<hints/>
313directories, or new subdirectories and F<README> files at the top level of the
314source tree.
3cd56aaa 315
4eabcf70 316=over 4
3cd56aaa 317
4eabcf70 318=item XXX-some-platform
3cd56aaa 319
4eabcf70 320XXX
c0c19433 321
4eabcf70 322=back
c0c19433 323
4eabcf70 324=head2 Discontinued Platforms
7ab2ea42 325
4eabcf70 326XXX List any platforms that this version of perl no longer compiles on.
7ab2ea42 327
4eabcf70 328=over 4
7ab2ea42 329
4eabcf70 330=item XXX-some-platform
7ab2ea42 331
4eabcf70 332XXX
90519d0f 333
4eabcf70 334=back
90519d0f 335
4eabcf70 336=head2 Platform-Specific Notes
90519d0f 337
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338XXX List any changes for specific platforms. This could include configuration
339and compilation changes or changes in portability/compatibility. However,
340changes within modules for platforms should generally be listed in the
341L</Modules and Pragmata> section.
90519d0f 342
4eabcf70 343=over 4
90519d0f 344
4eabcf70 345=item XXX-some-platform
90519d0f 346
4eabcf70 347XXX
90519d0f 348
4eabcf70 349=back
90519d0f 350
4eabcf70 351=head1 Internal Changes
90519d0f 352
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353XXX Changes which affect the interface available to C<XS> code go here.
354Other significant internal changes for future core maintainers should
355be noted as well.
90519d0f 356
4eabcf70 357[ List each change as a =item entry ]
90519d0f 358
4eabcf70 359=over 4
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360
361=item *
362
4eabcf70 363XXX
90519d0f 364
4eabcf70 365=back
90519d0f 366
4eabcf70 367=head1 Selected Bug Fixes
90519d0f 368
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369XXX Important bug fixes in the core language are summarised here.
370Bug fixes in files in F<ext/> and F<lib/> are best summarised in
371L</Modules and Pragmata>.
90519d0f 372
4eabcf70 373[ List each fix as a =item entry ]
90519d0f 374
4eabcf70 375=over 4
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376
377=item *
378
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379C<\w> now matches the code points U+200C (ZERO WIDTH NON-JOINER) and
380U+200D (ZERO WIDTH JOINER). C<\W> no longer matches these. This change
381is because Unicode corrected their definition of what C<\w> should match.
90519d0f 382
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383=item *
384
385C<dump LABEL> no longer leaks its label.
386
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387=item *
388
389Constant folding no longer changes the behaviour of functions like C<stat>
390and C<truncate> that can take either filenames or handles.
391C<stat 1 ? foo : bar> nows treats its argument as a file name (since it is
392an arbitrary expression), rather than the handle "foo".
393
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394=item *
395
396C<truncate FOO, $len> no longer falls back to treating "FOO" as a file name
397if the filehandle has been deleted. This was broken in Perl 5.16.0.
398
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399=item *
400
401Subroutine redefinitions after sub-to-glob and glob-to-glob assignments no
402longer cause double frees or panic messages.
403
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404=item *
405
406C<s///> now turns vstrings into plain strings when performing a
407substitution, even if the resulting string is the same (C<s/a/a/>).
408
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409=item *
410
411Prototype mismatch warnings no longer erroneously treat constant subs as
412having no prototype when they actually have "".
413
414=item *
415
416Constant subroutines and forward declarations no longer prevent prototype
417mismatch warnings from omitting the sub name.
418
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419=item *
420
421C<undef> on a subroutine now clears call checkers.
422
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423=item *
424
425The C<ref> operator started leaking memory on blessed objects in Perl
4265.16.0. This has been fixed [perl #114340].
427
4eabcf70 428=back
90519d0f 429
4eabcf70 430=head1 Known Problems
b8a55fe7 431
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432XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
433tests that had to be C<TODO>ed for the release would be noted here. Unfixed
434platform specific bugs also go here.
b8a55fe7 435
4eabcf70 436[ List each fix as a =item entry ]
b8a55fe7 437
4eabcf70 438=over 4
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439
440=item *
441
4eabcf70 442XXX
b8a55fe7 443
4eabcf70 444=back
5073ffbd 445
4eabcf70 446=head1 Obituary
5073ffbd 447
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448XXX If any significant core contributor has died, we've added a short obituary
449here.
e128ab2c 450
61174fb5 451=head1 Acknowledgements
d5dc7001 452
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453XXX Generate this with:
454
455 perl Porting/acknowledgements.pl v5.17.2..HEAD
29cf780c 456
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457=head1 Reporting Bugs
458
459If you find what you think is a bug, you might check the articles
52deee2e 460recently posted to the comp.lang.perl.misc newsgroup and the perl
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461bug database at http://rt.perl.org/perlbug/ . There may also be
462information at http://www.perl.org/ , the Perl Home Page.
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463
464If you believe you have an unreported bug, please run the L<perlbug>
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465program included with your release. Be sure to trim your bug down
466to a tiny but sufficient test case. Your bug report, along with the
467output of C<perl -V>, will be sent off to perlbug@perl.org to be
468analysed by the Perl porting team.
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469
470If the bug you are reporting has security implications, which make it
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471inappropriate to send to a publicly archived mailing list, then please send
472it to perl5-security-report@perl.org. This points to a closed subscription
473unarchived mailing list, which includes
474all the core committers, who will be able
475to help assess the impact of issues, figure out a resolution, and help
476co-ordinate the release of patches to mitigate or fix the problem across all
477platforms on which Perl is supported. Please only use this address for
478security issues in the Perl core, not for modules independently
479distributed on CPAN.
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480
481=head1 SEE ALSO
482
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483The F<Changes> file for an explanation of how to view exhaustive details
484on what changed.
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485
486The F<INSTALL> file for how to build Perl.
487
488The F<README> file for general stuff.
489
490The F<Artistic> and F<Copying> files for copyright information.
491
492=cut