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perldelta for given aliasing $_
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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
e96e0834 132=back
95c6c5c5 133
4eabcf70 134=head2 Removed Modules and Pragmata
95c6c5c5 135
e96e0834 136=over 4
95c6c5c5 137
95c6c5c5
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138=item *
139
4eabcf70 140XXX
4f85bc45 141
4eabcf70 142=back
72267260 143
4eabcf70 144=head1 Documentation
72267260 145
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146XXX Changes to files in F<pod/> go here. Consider grouping entries by
147file and be sure to link to the appropriate page, e.g. L<perlfunc>.
4f85bc45 148
4eabcf70 149=head2 New Documentation
7d101ed1 150
4eabcf70 151XXX Changes which create B<new> files in F<pod/> go here.
e013ada0 152
4eabcf70 153=head3 L<XXX>
4f85bc45 154
4eabcf70 155XXX Description of the purpose of the new file here
e013ada0 156
4eabcf70 157=head2 Changes to Existing Documentation
95c6c5c5 158
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159XXX Changes which significantly change existing files in F<pod/> go here.
160However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
161section.
95c6c5c5 162
be28af6e 163=head3 L<perlfunc>, L<perlop>
95c6c5c5 164
e96e0834 165=over 4
95c6c5c5
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166
167=item *
168
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169Loop control verbs (C<dump>, C<goto>, C<next>, C<last> and C<redo>) have
170always had the same precedence as assignment operators, but this was never
171documented until now.
95c6c5c5 172
e96e0834 173=back
95c6c5c5 174
4eabcf70 175=head1 Diagnostics
05c8f9ed 176
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177The following additions or changes have been made to diagnostic output,
178including warnings and fatal error messages. For the complete list of
179diagnostic messages, see L<perldiag>.
ceb0881c 180
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181XXX New or changed warnings emitted by the core's C<C> code go here. Also
182include any changes in L<perldiag> that reconcile it to the C<C> code.
0998713f 183
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184[ Within each section, list entries as a =item entry that links to perldiag,
185 e.g.
112b6866 186
4eabcf70 187 =item *
112b6866 188
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189 L<Invalid version object|perldiag/"Invalid version object">
190]
42d72fc5 191
4eabcf70 192=head2 New Diagnostics
42d72fc5 193
4eabcf70 194XXX Newly added diagnostic messages go here
8e125188 195
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196=over 4
197
198=item *
199
200Attempts to put wide characters into environment variables via %ENV provoke
201the warning "Wide character in setenv".
202
203=back
204
4eabcf70 205=head3 New Errors
8e125188 206
e96e0834 207=over 4
e128ab2c 208
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209=item *
210
4eabcf70 211XXX L<message|perldiag/"message">
16e4fcbf 212
4eabcf70 213=back
e2f0c3bb 214
4eabcf70 215=head3 New Warnings
90519d0f 216
4eabcf70 217=over 4
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218
219=item *
220
4eabcf70 221XXX L<message|perldiag/"message">
90519d0f 222
61174fb5 223=back
422287bf 224
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225=head2 Changes to Existing Diagnostics
226
227XXX Changes (i.e. rewording) of diagnostic messages go here
2de6ba8d 228
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229=over 4
230
231=item *
232
4eabcf70 233XXX Describe change here
e128ab2c 234
4eabcf70 235=back
8b1adbab 236
4eabcf70 237=head1 Utility Changes
8b1adbab 238
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239XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
240here. Most of these are built within the directories F<utils> and F<x2p>.
83f29afa 241
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242[ List utility changes as a =head3 entry for each utility and =item
243entries for each change
244Use L<XXX> with program names to get proper documentation linking. ]
83f29afa 245
4eabcf70 246=head3 L<XXX>
0938f143 247
4eabcf70 248=over 4
0938f143 249
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250=item *
251
4eabcf70 252XXX
7a251f7a 253
4eabcf70 254=back
7a251f7a 255
4eabcf70 256=head1 Configuration and Compilation
21247d85 257
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258XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
259go here. Any other changes to the Perl build process should be listed here.
260However, any platform-specific changes should be listed in the
261L</Platform Support> section, instead.
21247d85 262
4eabcf70 263[ List changes as a =item entry ].
2e4f8b82 264
4eabcf70 265=over 4
c95d4104 266
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267=item *
268
4eabcf70 269XXX
788505db 270
4eabcf70 271=back
2c2b9cf4 272
4eabcf70 273=head1 Testing
3cd56aaa 274
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275XXX Any significant changes to the testing of a freshly built perl should be
276listed here. Changes which create B<new> files in F<t/> go here as do any
277large changes to the testing harness (e.g. when parallel testing was added).
278Changes to existing files in F<t/> aren't worth summarising, although the bugs
279that they represent may be covered elsewhere.
3cd56aaa 280
4eabcf70 281[ List each test improvement as a =item entry ]
3cd56aaa 282
4eabcf70 283=over 4
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284
285=item *
286
4eabcf70 287XXX
3cd56aaa 288
4eabcf70 289=back
3cd56aaa 290
4eabcf70 291=head1 Platform Support
3cd56aaa 292
4eabcf70 293XXX Any changes to platform support should be listed in the sections below.
3cd56aaa 294
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295[ Within the sections, list each platform as a =item entry with specific
296changes as paragraphs below it. ]
3cd56aaa 297
4eabcf70 298=head2 New Platforms
3cd56aaa 299
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300XXX List any platforms that this version of perl compiles on, that previous
301versions did not. These will either be enabled by new files in the F<hints/>
302directories, or new subdirectories and F<README> files at the top level of the
303source tree.
3cd56aaa 304
4eabcf70 305=over 4
3cd56aaa 306
4eabcf70 307=item XXX-some-platform
3cd56aaa 308
4eabcf70 309XXX
c0c19433 310
4eabcf70 311=back
c0c19433 312
4eabcf70 313=head2 Discontinued Platforms
7ab2ea42 314
4eabcf70 315XXX List any platforms that this version of perl no longer compiles on.
7ab2ea42 316
4eabcf70 317=over 4
7ab2ea42 318
4eabcf70 319=item XXX-some-platform
7ab2ea42 320
4eabcf70 321XXX
90519d0f 322
4eabcf70 323=back
90519d0f 324
4eabcf70 325=head2 Platform-Specific Notes
90519d0f 326
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327XXX List any changes for specific platforms. This could include configuration
328and compilation changes or changes in portability/compatibility. However,
329changes within modules for platforms should generally be listed in the
330L</Modules and Pragmata> section.
90519d0f 331
4eabcf70 332=over 4
90519d0f 333
4eabcf70 334=item XXX-some-platform
90519d0f 335
4eabcf70 336XXX
90519d0f 337
4eabcf70 338=back
90519d0f 339
4eabcf70 340=head1 Internal Changes
90519d0f 341
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342XXX Changes which affect the interface available to C<XS> code go here.
343Other significant internal changes for future core maintainers should
344be noted as well.
90519d0f 345
4eabcf70 346[ List each change as a =item entry ]
90519d0f 347
4eabcf70 348=over 4
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349
350=item *
351
4eabcf70 352XXX
90519d0f 353
4eabcf70 354=back
90519d0f 355
4eabcf70 356=head1 Selected Bug Fixes
90519d0f 357
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358XXX Important bug fixes in the core language are summarised here.
359Bug fixes in files in F<ext/> and F<lib/> are best summarised in
360L</Modules and Pragmata>.
90519d0f 361
4eabcf70 362[ List each fix as a =item entry ]
90519d0f 363
4eabcf70 364=over 4
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365
366=item *
367
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368C<\w> now matches the code points U+200C (ZERO WIDTH NON-JOINER) and
369U+200D (ZERO WIDTH JOINER). C<\W> no longer matches these. This change
370is because Unicode corrected their definition of what C<\w> should match.
90519d0f 371
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372=item *
373
374C<dump LABEL> no longer leaks its label.
375
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376=item *
377
378Constant folding no longer changes the behaviour of functions like C<stat>
379and C<truncate> that can take either filenames or handles.
380C<stat 1 ? foo : bar> nows treats its argument as a file name (since it is
381an arbitrary expression), rather than the handle "foo".
382
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383=item *
384
385C<truncate FOO, $len> no longer falls back to treating "FOO" as a file name
386if the filehandle has been deleted. This was broken in Perl 5.16.0.
387
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388=item *
389
390Subroutine redefinitions after sub-to-glob and glob-to-glob assignments no
391longer cause double frees or panic messages.
392
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393=item *
394
395C<s///> now turns vstrings into plain strings when performing a
396substitution, even if the resulting string is the same (C<s/a/a/>).
397
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398=item *
399
400Prototype mismatch warnings no longer erroneously treat constant subs as
401having no prototype when they actually have "".
402
403=item *
404
405Constant subroutines and forward declarations no longer prevent prototype
406mismatch warnings from omitting the sub name.
407
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408=item *
409
410C<undef> on a subroutine now clears call checkers.
411
4eabcf70 412=back
90519d0f 413
4eabcf70 414=head1 Known Problems
b8a55fe7 415
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416XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
417tests that had to be C<TODO>ed for the release would be noted here. Unfixed
418platform specific bugs also go here.
b8a55fe7 419
4eabcf70 420[ List each fix as a =item entry ]
b8a55fe7 421
4eabcf70 422=over 4
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423
424=item *
425
4eabcf70 426XXX
b8a55fe7 427
4eabcf70 428=back
5073ffbd 429
4eabcf70 430=head1 Obituary
5073ffbd 431
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432XXX If any significant core contributor has died, we've added a short obituary
433here.
e128ab2c 434
61174fb5 435=head1 Acknowledgements
d5dc7001 436
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437XXX Generate this with:
438
439 perl Porting/acknowledgements.pl v5.17.2..HEAD
29cf780c 440
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441=head1 Reporting Bugs
442
443If you find what you think is a bug, you might check the articles
52deee2e 444recently posted to the comp.lang.perl.misc newsgroup and the perl
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445bug database at http://rt.perl.org/perlbug/ . There may also be
446information at http://www.perl.org/ , the Perl Home Page.
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447
448If you believe you have an unreported bug, please run the L<perlbug>
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449program included with your release. Be sure to trim your bug down
450to a tiny but sufficient test case. Your bug report, along with the
451output of C<perl -V>, will be sent off to perlbug@perl.org to be
452analysed by the Perl porting team.
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453
454If the bug you are reporting has security implications, which make it
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455inappropriate to send to a publicly archived mailing list, then please send
456it to perl5-security-report@perl.org. This points to a closed subscription
457unarchived mailing list, which includes
458all the core committers, who will be able
459to help assess the impact of issues, figure out a resolution, and help
460co-ordinate the release of patches to mitigate or fix the problem across all
461platforms on which Perl is supported. Please only use this address for
462security issues in the Perl core, not for modules independently
463distributed on CPAN.
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464
465=head1 SEE ALSO
466
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467The F<Changes> file for an explanation of how to view exhaustive details
468on what changed.
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469
470The F<INSTALL> file for how to build Perl.
471
472The F<README> file for general stuff.
473
474The F<Artistic> and F<Copying> files for copyright information.
475
476=cut