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perldelta for [perl #68712]
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1=encoding utf8
2
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4c9d53d5 4This has been completed up to b2ef6d44, except for:
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10=head1 NAME
11
12[ this is a template for a new perldelta file. Any text flagged as
13XXX needs to be processed before release. ]
14
15perldelta - what is new for perl v5.13.8
16
17=head1 DESCRIPTION
18
19This document describes differences between the 5.13.8 release and
20the 5.13.7 release.
21
dbbe2d83 22If you are upgrading from an earlier release such as 5.13.6, first read
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23L<perl5137delta>, which describes differences between 5.13.6 and
245.13.7.
25
26=head1 Notice
27
28XXX Any important notices here
29
30=head1 Core Enhancements
31
32XXX New core language features go here. Summarise user-visible core language
33enhancements. Particularly prominent performance optimisations could go
34here, but most should go in the L</Performance Enhancements> section.
35
36[ List each enhancement as a =head2 entry ]
37
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38=head2 C<-d:-foo> calls C<Devel::foo::unimport>
39
40The syntax C<-dI<B<:>foo>> was extended in 5.6.1 to make C<-dI<:fooB<=bar>>>
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41equivalent to C<-MDevel::foo=bar>, which expands
42internally to C<use Devel::foo 'bar';>.
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43F<perl> now allows prefixing the module name with C<->, with the same
44semantics as C<-M>, I<i.e.>
45
46=over 4
47
48=item C<-d:-foo>
49
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50Equivalent to C<-M-Devel::foo>, expands to
51C<no Devel::foo;>, calls C<< Devel::foo->unimport() >>
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52if the method exists.
53
54=item C<-d:-foo=bar>
55
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56Equivalent to C<-M-Devel::foo=bar>, expands to C<no Devel::foo 'bar';>,
57calls C<< Devel::foo->unimport('bar') >> if the method exists.
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58
59=back
60
61This is particularly useful to suppresses the default actions of a
62C<Devel::*> module's C<import> method whilst still loading it for debugging.
63
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64=head2 Filehandle method calls load IO::File on demand
65
66When a method call on a filehandle would die because the method can not
67be resolved and L<IO::File> has not been loaded, Perl now loads IO::File
68via C<require> and attempts method resolution again:
69
70 open my $fh, ">", $file;
71 $fh->binmode(":raw"); # loads IO::File and succeeds
72
73This also works for globs like STDOUT, STDERR and STDIN:
74
75 STDOUT->autoflush(1);
76
77Because this on-demand load only happens if method resolution fails, the
78legacy approach of manually loading an IO::File parent class for partial
79method support still works as expected:
80
81 use IO::Handle;
82 open my $fh, ">", $file;
83 $fh->autoflush(1); # IO::File not loaded
84
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85=head2 Full functionality for C<use feature 'unicode_strings'>
86
87This release provides full functionality for C<use feature
88'unicode_strings'>. Under its scope, all string operations executed and
89regular expressions compiled (even if executed outside its scope) have
90Unicode semantics. See L<feature>.
91
92This feature avoids the "Unicode Bug" (See
93L<perlunicode/The "Unicode Bug"> for details.) If their is a
94possibility that your code will process Unicode strings, you are
95B<strongly> encouraged to use this subpragma to avoid nasty surprises.
96
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97This availability of this should strongly affect the whole tone of
98various documents, such as L<perlunicode> and L<perluniintro>, but this
99work has not been done yet.
100
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101=head2 Exception Handling Backcompat Hack
102
103When an exception is thrown in an C<eval BLOCK>, C<$@> is now set before
104unwinding, as well as being set after unwinding as the eval block exits. This
105early setting supports code that has historically treated C<$@> during unwinding
106as an indicator of whether the unwinding was due to an exception. These modules
107had been broken by 5.13.1's change from setting C<$@> early to setting it late.
108This double setting arrangement is a stopgap until the reason for unwinding can
109be made properly introspectable. C<$@> has never been a reliable indicator of
110this.
111
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112=head1 Security
113
114XXX Any security-related notices go here. In particular, any security
115vulnerabilities closed should be noted here rather than in the
116L</Selected Bug Fixes> section.
117
118[ List each security issue as a =head2 entry ]
119
120=head1 Incompatible Changes
121
2dc78664 122=head2 Attempting to use C<:=> as an empty attribute list is now a syntax error
3a5c9134 123
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124Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
125with the C<:> being treated as the start of an attribute list, ending before
126the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is now
127a syntax error. This will allow the future use of C<:=> as a new token.
3a5c9134 128
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129We find no Perl 5 code on CPAN using this construction, outside the core's
130tests for it, so we believe that this change will have very little impact on
131real-world codebases.
132
133If it is absolutely necessary to have empty attribute lists (for example,
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134because of a code generator) then avoid the error by adding a space before
135the C<=>.
3a5c9134 136
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137=head2 Run-time code block in regular expressions
138
139Code blocks in regular expressions (C<(?{...})> and C<(??{...})>) used not
140to inherit any pragmata (strict, warnings, etc.) if the regular expression
141was compiled at run time as happens in cases like these two:
142
143 use re 'eval';
144 $foo =~ $bar; # when $bar contains (?{...})
145 $foo =~ /$bar(?{ $finished = 1 })/;
146
147This was a bug, which has now been fixed. But it has the potential to break
148any code that was relying on this bug.
149
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150=head1 Deprecations
151
152XXX Any deprecated features, syntax, modules etc. should be listed here.
153In particular, deprecated modules should be listed here even if they are
154listed as an updated module in the L</Modules and Pragmata> section.
155
156[ List each deprecation as a =head2 entry ]
157
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158=head2 C<?PATTERN?> is deprecated
159
160C<?PATTERN?> (without the initial m) has been deprecated and now produces
161a warning.
162
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163=head2 C<sv_compile_2op> is now deprecated
164
165The C<sv_compile_2op> is now deprecated, and will be removed. Searches suggest
166that nothing on CPAN is using it, so this should have zero impact.
167
168It attempted to provide an API to compile code down to an optree, but failed
169to bind correctly to lexicals in the enclosing scope. It's not possible to
170fix this problem within the constraints of its parameters and return value.
171
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172=head2 Tie functions on scalars holding typeglobs
173
174Calling a tie function (C<tie>, C<tied>, C<untie>) with a scalar argument
175acts on a file handle if the scalar happens to hold a typeglob.
176
177This is a long-standing bug that will be removed in Perl 5.16, as
178there is currently no way to tie the scalar itself when it holds
179a typeglob, and no way to untie a scalar that has had a typeglob
180assigned to it.
181
182This bug was fixed in 5.13.7 but, because of the breakage it caused, the
183fix has been reverted. Now there is a deprecation warning whenever a tie
184function is used on a handle without an explicit C<*>.
185
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186=head1 Performance Enhancements
187
188XXX Changes which enhance performance without changing behaviour go here. There
189may well be none in a stable release.
190
191[ List each enhancement as a =item entry ]
192
193=over 4
194
195=item *
196
197XXX
198
199=back
200
201=head1 Modules and Pragmata
202
203XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
204go here. If Module::CoreList is updated, generate an initial draft of the
205following sections using F<Porting/corelist-perldelta.pl>, which prints stub
206entries to STDOUT. Results can be pasted in place of the '=head2' entries
207below. A paragraph summary for important changes should then be added by hand.
208In an ideal world, dual-life modules would have a F<Changes> file that could be
209cribbed.
210
211[ Within each section, list entries as a =item entry ]
212
213=head2 New Modules and Pragmata
214
215=over 4
216
217=item *
218
219XXX
220
221=back
222
223=head2 Updated Modules and Pragmata
224
225=over 4
226
227=item *
228
8172cd69 229C<ExtUtils::CBuilder> has been upgraded from 0.2703 to 0.2801
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230
231=item *
232
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233C<if> has been upgraded from 0.06 to 0.0601.
234
235=item *
236
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237C<Devel::SelfStubber> has been upgraded from version 1.03 to 1.04.
238
239=item *
240
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241C<IPC::Cmd> has been upgraded from 0.64 to 0.66
242
243Resolves an issue with splitting Win32 command lines
244and documentation enhancements.
245
246=item *
247
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248C<Locale::Codes> has been upgraded from version 3.14 to 3.15
249
250=item *
251
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252C<Memoize> has been upgraded from version 1.01_03 to 1.02.
253
254=item *
255
37fa6334 256C<MIME::Base64> has been upgraded from 3.10 to 3.13
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257
258Now provides encode_base64url and decode_base64url functions to process
259the base64 scheme for "URL applications".
260
261=item *
262
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263C<mro> has been upgraded from version 1.05 to 1.06.
264
265C<next::method> I<et al.> now take into account that every class inherits
266from UNIVERSAL
267L<[perl #68654]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68654>.
268
269=item *
270
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271C<overload> has been upgraded from 1.11 to 1.12.
272
273=item *
274
275C<PerlIO::scalar> has been upgraded from 0.10 to 0.11.
276
277A C<read> after a C<seek> beyond the end of the string no longer thinks it
278has data to read
279L<[perl #78716]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=78716>.
280
281=item *
282
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283C<re> has been upgraded from 0.14 to 0.15.
284
285=item *
286
5ebfb99c 287C<Socket> has been upgraded from 1.91 to 1.92.
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288
289It has several new functions for handling IPv6 addresses.
290
291=item *
292
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293C<Storable> has been upgraded from 2.24 to 2.25.
294
295This adds support for serialising code references that contain UTF-8 strings
296correctly. The Storable minor version number changed as a result -- this means
297Storable users that set C<$Storable::accept_future_minor> to a C<FALSE> value
298will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
299
300=item *
301
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302C<Time::HiRes> has been upgraded from 1.9721 to 1.9721_01.
303
304=item *
305
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306C<Unicode::Collate> has been upgraded from 0.67 to 0.68
307
308=item *
309
59773fc7 310C<Unicode::UCD> has been upgraded from 0.29 to 0.30.
3a5c9134 311
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312=item *
313
314C<version> has been upgraded from 0.82 to 0.86.
315
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316=item *
317
318C<Win32> has been upgraded from 0.039 to 0.040.
319
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320=back
321
322=head2 Removed Modules and Pragmata
323
324=over 4
325
326=item *
327
328XXX
329
330=back
331
332=head1 Documentation
333
334XXX Changes to files in F<pod/> go here. Consider grouping entries by
335file and be sure to link to the appropriate page, e.g. L<perlfunc>.
336
337=head2 New Documentation
338
339XXX Changes which create B<new> files in F<pod/> go here.
340
341=head3 L<XXX>
342
343XXX Description of the purpose of the new file here
344
345=head2 Changes to Existing Documentation
346
347XXX Changes which significantly change existing files in F<pod/> go here.
348However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
349section.
350
351=head3 L<XXX>
352
353=over 4
354
355=item *
356
357XXX Description of the change here
358
359=back
360
361=head1 Diagnostics
362
363The following additions or changes have been made to diagnostic output,
364including warnings and fatal error messages. For the complete list of
365diagnostic messages, see L<perldiag>.
366
367XXX New or changed warnings emitted by the core's C<C> code go here. Also
368include any changes in L<perldiag> that reconcile it to the C<C> code.
369
370[ Within each section, list entries as a =item entry ]
371
372=head2 New Diagnostics
373
374XXX Newly added diagnostic messages go here
375
376=over 4
377
378=item *
379
4d4ca6a5 380There is a new "Closure prototype called" error.
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381
382=back
383
384=head2 Changes to Existing Diagnostics
385
386XXX Changes (i.e. rewording) of diagnostic messages go here
387
388=over 4
389
390=item *
391
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392The "Found = in conditional" warning that is emitted when a constant is
393assigned to a variable in a condition is now withheld if the constant is
394actually a subroutine or one generated by C<use constant>, since the value
395of the constant may not be known at the time the program is written
396L<[perl #77762]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=77762>.
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397
398=back
399
400=head1 Utility Changes
401
402XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
403here. Most of these are built within the directories F<utils> and F<x2p>.
404
405[ List utility changes as a =head3 entry for each utility and =item
406entries for each change
407Use L<XXX> with program names to get proper documentation linking. ]
408
409=head3 L<XXX>
410
411=over 4
412
413=item *
414
415XXX
416
417=back
418
419=head1 Configuration and Compilation
420
421XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
422go here. Any other changes to the Perl build process should be listed here.
423However, any platform-specific changes should be listed in the
424L</Platform Support> section, instead.
425
426[ List changes as a =item entry ].
427
428=over 4
429
430=item *
431
432XXX
433
434=back
435
436=head1 Testing
437
438XXX Any significant changes to the testing of a freshly built perl should be
439listed here. Changes which create B<new> files in F<t/> go here as do any
440large changes to the testing harness (e.g. when parallel testing was added).
441Changes to existing files in F<t/> aren't worth summarising, although the bugs
442that they represent may be covered elsewhere.
443
444[ List each test improvement as a =item entry ]
445
446=over 4
447
448=item *
449
450XXX
451
452=back
453
454=head1 Platform Support
455
456XXX Any changes to platform support should be listed in the sections below.
457
458[ Within the sections, list each platform as a =item entry with specific
459changes as paragraphs below it. ]
460
461=head2 New Platforms
462
463XXX List any platforms that this version of perl compiles on, that previous
464versions did not. These will either be enabled by new files in the F<hints/>
465directories, or new subdirectories and F<README> files at the top level of the
466source tree.
467
468=over 4
469
470=item XXX-some-platform
471
472XXX
473
474=back
475
476=head2 Discontinued Platforms
477
478XXX List any platforms that this version of perl no longer compiles on.
479
480=over 4
481
482=item XXX-some-platform
483
484XXX
485
486=back
487
488=head2 Platform-Specific Notes
489
490XXX List any changes for specific platforms. This could include configuration
491and compilation changes or changes in portability/compatibility. However,
492changes within modules for platforms should generally be listed in the
493L</Modules and Pragmata> section.
494
495=over 4
496
085d0904 497=item NetBSD
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499The NetBSD hints file has been changed to make the system's malloc the
500default.
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501
502=back
503
504=head1 Internal Changes
505
506XXX Changes which affect the interface available to C<XS> code go here.
507Other significant internal changes for future core maintainers should
508be noted as well.
509
510[ List each test improvement as a =item entry ]
511
512=over 4
513
514=item *
515
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516C<mg_findext> and C<sv_unmagicext> have been added.
517
518These new functions allow extension authors to find and remove magic attached to
519scalars based on both the magic type and the magic virtual table, similar to how
520C<sv_magicext> attaches magic of a certain type and with a given virtual table
521to a scalar. This eliminates the need for extensions to walk the list of
522C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
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523
524=back
525
526=head1 Selected Bug Fixes
527
528XXX Important bug fixes in the core language are summarised here.
529Bug fixes in files in F<ext/> and F<lib/> are best summarised in
530L</Modules and Pragmata>.
531
532[ List each fix as a =item entry ]
533
534=over 4
535
536=item *
537
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538C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
539identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
540was erroneously executing the C<use feature ':5.12.0'> and
541C<use strict; use warnings;> behaviour, which only C<use> was documented to
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542provide
543L<[perl #69050]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=69050>.
544
545=item *
546
547C<use 5.42>
548L<[perl #69050]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=69050>,
549C<use 6> and C<no 5> no longer leak memory.
550
551=item *
552
553C<eval "BEGIN{die}"> no longer leaks memory on non-threaded builds.
3a5c9134 554
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555=item *
556
557PerlIO no longer crashes when called recursively, e.g., from a signal
558handler. Now it just leaks memory
559L<[perl #75556]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=75556>.
560
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561=item *
562
563Defining a constant with the same name as one of perl's special blocks
564(e.g., INIT) stopped working in 5.12.0, but has now been fixed
565L<[perl #78634]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=78634>.
566
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567=item *
568
569A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
570to be stringified, even if the hash was tied
571L<[perl #79178]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=79178>.
572
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573=item *
574
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575A closure containing an C<if> statement followed by a constant or variable
576is no longer treated as a constant
577L<[perl #63540]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=63540>.
578
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579=item *
580
581Calling a closure prototype (what is passed to an attribute handler for a
582closure) now results in a "Closure prototype called" error message
583L<[perl #68560]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68560>.
584
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585=item *
586
587A regular expression optimisation would sometimes cause a match with a
588C<{n,m}> quantifier to fail when it should match
589L<[perl #79152]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=79152>.
590
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591=item *
592
593What has become known as the "Unicode Bug" is resolved in this release.
594Under C<use feature 'unicode_strings'>, the internal storage format of a
595string no longer affects the external semantics. There are two known
596exceptions. User-defined case changing functions, which are planned to
597be deprecated in 5.14, require utf8-encoded strings to function; and the
598character C<LATIN SMALL LETTER SHARP S> in regular expression
599case-insensitive matching has a somewhat different set of bugs depending
600on the internal storage format. Case-insensitive matching of all
601characters that have multi-character matches, as this one does, is
602problematical in Perl.
603L<[perl #58182]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=58182>.
604
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605=item *
606
607Mentioning a read-only lexical variable from the enclosing scope in a
608string C<eval> would cause the variable to become writable
609L<[perl #19135]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=19135>.
610
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611=item *
612
613C<state> can now be used with attributes. It used to mean the same thing as
614C<my> if attributes were present
615L<[perl #68658]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68658>.
616
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617=item *
618
619Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
620the "Use of uninitialized value in numeric gt" warning when C<$a> is
621undefined (since it is not part of the C<E<gt>> expression, but the operand
622of the C<@>)
623L<[perl #72090]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=72090>.
624
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625=item *
626
627C<require> no longer causes C<caller> to return the wrong file name for
628the scope that called C<require> and other scopes higher up that had the
629same file name
630L<[perl #68712]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68712>.
631
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632=back
633
634=head1 Known Problems
635
636XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
637tests that had to be C<TODO>ed for the release would be noted here, unless
638they were specific to a particular platform (see below).
639
640This is a list of some significant unfixed bugs, which are regressions
641from either 5.XXX.XXX or 5.XXX.XXX.
642
643[ List each fix as a =item entry ]
644
645=over 4
646
647=item *
648
3ad6135d 649XXX
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650
651=back
652
653=head1 Obituary
654
655XXX If any significant core contributor has died, we've added a short obituary
656here.
657
658=head1 Acknowledgements
659
660XXX The list of people to thank goes here.
661
662=head1 Reporting Bugs
663
664If you find what you think is a bug, you might check the articles
665recently posted to the comp.lang.perl.misc newsgroup and the perl
666bug database at http://rt.perl.org/perlbug/ . There may also be
667information at http://www.perl.org/ , the Perl Home Page.
668
669If you believe you have an unreported bug, please run the L<perlbug>
670program included with your release. Be sure to trim your bug down
671to a tiny but sufficient test case. Your bug report, along with the
672output of C<perl -V>, will be sent off to perlbug@perl.org to be
673analysed by the Perl porting team.
674
675If the bug you are reporting has security implications, which make it
676inappropriate to send to a publicly archived mailing list, then please send
677it to perl5-security-report@perl.org. This points to a closed subscription
678unarchived mailing list, which includes all the core committers, who be able
679to help assess the impact of issues, figure out a resolution, and help
680co-ordinate the release of patches to mitigate or fix the problem across all
681platforms on which Perl is supported. Please only use this address for
682security issues in the Perl core, not for modules independently
683distributed on CPAN.
684
685=head1 SEE ALSO
686
687The F<Changes> file for an explanation of how to view exhaustive details
688on what changed.
689
690The F<INSTALL> file for how to build Perl.
691
692The F<README> file for general stuff.
693
694The F<Artistic> and F<Copying> files for copyright information.
695
696=cut