This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
the rmg should tell BLEAD-POINT to bump version at the end
[perl5.git] / pod / perldelta.pod
CommitLineData
44691e6f
AB
1=encoding utf8
2
3=head1 NAME
4
61174fb5 5perldelta - what is new for perl v5.17.1
27f00e3d 6
f9001595 7=head1 DESCRIPTION
2630d42b 8
61174fb5
Z
9This document describes differences between the 5.17.0 release and
10the 5.17.1 release.
7620cb10 11
f9001595 12If you are upgrading from an earlier release such as 5.16.0, first read
61174fb5
Z
13L<perl5170delta>, which describes differences between 5.16.0 and
145.17.0.
d7c042c9 15
61174fb5 16=head1 Core Enhancements
417a992d 17
028c8719
FC
18=head2 More CORE:: subs
19
20Several more built-in functions have been added as subroutines to the
21CORE:: namespace, namely, those non-overridable keywords that can be
22implemented without custom parsers: C<defined>, C<delete>, C<exists>,
f1303084 23C<glob>, C<pos>, C<protoytpe>, C<scalar>, C<split>, C<study>, and C<undef>.
028c8719
FC
24
25As some of these have prototypes, C<prototype('CORE::...')> has been
b1c9e38d 26changed to not make a distinction between overridable and non-overridable
028c8719
FC
27keywords. This is to make C<prototype('CORE::pos')> consistent with
28C<prototype(&CORE::pos)>.
29
61174fb5 30=head1 Incompatible Changes
30608892 31
954945b8 32=head2 C</(?{})/> and C</(??{})/> have been heavily reworked
e128ab2c 33
b1c9e38d 34The implementation of this feature has been almost completely rewritten.
954945b8 35Although its main intent is to fix bugs, some behaviors, especially
e128ab2c
DM
36related to the scope of lexical variables, will have changed. This is
37described more fully in the L</Selected Bug Fixes> section.
38
fe3193b5
KW
39=head2 C<\N{BELL}> now refers to U+1F514 instead of U+0007
40
41Unicode 6.0 reused the name "BELL" for a different code point than it
42traditionally had meant. Since Perl v5.14, use of this name still
954945b8 43referred to U+0007, but would raise a deprecation warning. Now, "BELL"
fe3193b5
KW
44refers to U+1F514, and the name for U+0007 is "ALERT". All the
45functions in L<charnames> have been correspondingly updated.
05c8f9ed 46
0da72d5e 47=head2 Alphanumeric operators must now be separated from the closing
b1c9e38d 48delimiter of regular expressions
0da72d5e
KW
49
50You may no longer write something like:
51
52 m/a/and 1
53
54Instead you must write
55
56 m/a/ and 1
57
58with whitespace separating the operator from the closing delimiter of
59the regular expression. Not having whitespace has resulted in a
954945b8 60deprecation warning since Perl v5.14.0.
0da72d5e 61
e2f0c3bb
FC
62=head2 C<require> dies for unreadable files
63
64When C<require> encounters an unreadable file, it now dies. It used to
65ignore the file and continue searching the directories in @INC
66[perl #113422].
67
7d101ed1
JL
68=head2 Upgrade to the Unicode 6.2 beta
69
70Unicode 6.2 is proposing some changes that may very well break some CPAN
71modules. The timing of this nicely coincides with Perl's being early in the
72release cycle. This commit takes the current beta 6.2, adds the proposed
73changes that aren't yet in it, and subtracts the changes that would affect \X
74processing, as those turn out to have errors, and may have to be rethought.
75Unicode has been notified of these problems.
76
77This will allow us to gather data as to whether or not the proposed changes
78cause us problems. These will be presented to Unicode to aid in their final
79decision as to whether or not to go forward with the changes.
80
81These changes will be replaced by the final version of Unicode 6.2 before
825.18.0 is released.
83
61174fb5 84=head1 Performance Enhancements
95ce428c 85
f9001595 86=over 4
75ff5956 87
2630d42b 88=item *
c11980ad 89
e2f0c3bb
FC
90The C<x> repetition operator is now folded to a single constant at compile
91time if called in scalar context with constant operands and no parentheses
92around the left operand.
53de3ff0 93
61174fb5 94=back
ef7131e9 95
61174fb5 96=head1 Modules and Pragmata
ef7131e9 97
61174fb5 98=head2 Updated Modules and Pragmata
83fb037c 99
61174fb5 100=over 4
83fb037c
FC
101
102=item *
103
95c6c5c5 104L<Archive::Extract> has been upgraded from version 0.58 to 0.60.
c01b3876 105
95c6c5c5
JL
106Work around an edge case on Linux with Busybox's unzip.
107
108=item *
109
110L<Archive::Tar> has been upgraded from version 1.82 to 1.88.
111
954945b8
JL
112ptar now supports the -T option as well as dashless options
113[rt.cpan.org #75473], [rt.cpan.org #75475].
95c6c5c5
JL
114
115Auto-encode filenames marked as UTF-8 [rt.cpan.org #75474].
116
954945b8 117Don't use C<tell> on L<IO::Zlib> handles [rt.cpan.org #64339].
95c6c5c5
JL
118
119Don't try to C<chown> on symlinks.
120
121=item *
122
123L<attributes> has been upgraded from version 0.19 to 0.20.
124
95c6c5c5
JL
125=item *
126
127L<autodie> has been upgraded from version 2.10 to 2.11.
128
c01b3876
SH
129=item *
130
5cefbec9
FC
131L<B> has been upgraded from version 1.35 to 1.36.
132
133C<B::COP::stashlen> has been replaced with C<B::COP::stashoff>.
134
954945b8 135C<B::COP::stashpv> now supports UTF-8 package names and embedded NULs.
fbdb83f3 136
5cefbec9
FC
137=item *
138
95c6c5c5
JL
139L<B::Deparse> has been upgraded from version 1.14 to 1.15.
140
141Avoid warning when run under C<perl -w>.
142
143=item *
144
e2f0c3bb
FC
145L<Class::Struct> has been upgraded from version 0.63 to 0.64.
146
147The constructor now respects overridden accessor methods [perl #29230].
148
149=item *
150
95c6c5c5
JL
151L<Compress::Raw::Bzip2> has been upgraded from version 2.048 to 2.052.
152
95c6c5c5
JL
153=item *
154
155L<Compress::Raw::Zlib> has been upgraded from version 2.048 to 2.054.
156
157Upgrade bundled zlib to version 1.2.7.
158
159Fix build failures on Irix, Solaris, and Win32, and also when building as C++
160[rt.cpan.org #69985], [rt.cpan.org #77030], [rt.cpan.org #75222].
161
162=item *
163
164L<CPAN::Meta> has been upgraded from version 2.120630 to 2.120921.
165
95c6c5c5
JL
166=item *
167
168L<CPAN::Meta::Requirements> has been upgraded from version 2.120630 to 2.122.
169
170Treat undef requirements to C<from_string_hash> as 0 (with a warning).
171
172Added C<requirements_for_module> method.
173
174=item *
175
176L<CPAN::Meta::YAML> has been upgraded from version 0.007 to 0.008.
177
95c6c5c5
JL
178=item *
179
180L<CPANPLUS> has been upgraded from version 0.9121 to 0.9130.
181
182Allow adding F<blib/script> to PATH.
183
184Save the history between invocations of the shell.
185
186Handle multiple C<makemakerargs> and C<makeflags> arguments better.
187
188Use C<File::HomeDir> when available, and provide C<PERL5_CPANPLUS_HOME> to
189override the autodetection.
190
954945b8 191Always re-fetch F<CHECKSUMS> if C<fetchdir> is set.
95c6c5c5
JL
192
193=item *
194
195L<Digest::MD5> has been upgraded from version 2.51 to 2.52.
196
954945b8 197Fix C<Digest::Perl::MD5> OO fallback [rt.cpan.org #66634].
95c6c5c5
JL
198
199=item *
200
9331f04e
NC
201L<DynaLoader> has been upgraded from version 1.14 to 1.15.
202
203This is due to a minor code change in the XS for the VMS implementation.
204
205=item *
206
95c6c5c5
JL
207L<ExtUtils::CBuilder> has been upgraded from version 0.280206 to 0.280208.
208
209Manifest files are now correctly embedded for those versions of VC++ which
210make use of them. [perl #111782, #111798].
211
212=item *
213
ff3f295c
NC
214L<File::DosGlob> has been upgraded from version 1.07 to 1.08.
215
ff3f295c
NC
216=item *
217
95c6c5c5
JL
218L<File::Fetch> has been upgraded from version 0.32 to 0.34.
219
95c6c5c5
JL
220=item *
221
c506fc7e
FC
222L<File::Spec::Unix> has been upgraded from version 3.39_02 to 3.39_03.
223
224C<abs2rel> could produce incorrect results when given two relative paths or
225the root directory twice [perl #111510].
226
227=item *
228
95c6c5c5
JL
229L<Filter::Util::Call> has been upgraded from version 1.40 to 1.45.
230
95c6c5c5
JL
231=item *
232
233L<HTTP::Tiny> has been upgraded from version 0.017 to 0.022.
234
235Add SSL verification features [github #6], [github #9].
236
237Include the final URL in the response hashref.
238
239Add C<local_address> option.
240
241=item *
242
d9661073 243L<IO> has been upgraded from version 1.25_06 to 1.25_07.
1c633914 244
d9661073 245C<sync()> can now be called on read-only file handles [perl #64772].
f558db2f 246
66aa79e2
KW
247=item *
248
95c6c5c5
JL
249L<IPC::Cmd> has been upgraded from version 0.76 to 0.78.
250
251Use C<POSIX::_exit> instead of C<exit> in C<run_forked> [rt.cpan.org #76901].
252
253=item *
254
255L<Memoize> has been upgraded from version 1.02 to 1.03.
256
257Fix the C<MERGE> cache option.
258
259=item *
260
261L<Module::Build> has been upgraded from version 0.39_01 to 0.40.
262
263Fixed bug where modules without C<$VERSION> might have a version of '0' listed
264in 'provides' metadata, which will be rejected by PAUSE.
265
266Fixed bug in PodParser to allow numerals in module names.
267
268Fixed bug where giving arguments twice led to them becoming arrays, resulting
269in install paths like F<ARRAY(0xdeadbeef)/lib/Foo.pm>.
270
271=item *
272
71014848
JL
273L<Module::CoreList> has been upgraded from version 2.67 to 2.68.
274
275=item *
276
95c6c5c5
JL
277L<Module::Load::Conditional> has been upgraded from version 0.46 to 0.50.
278
279Fix use of C<requires> on perls installed to a path with spaces.
280
281=item *
282
283L<Object::Accessor> has been upgraded from version 0.42 to 0.44.
284
95c6c5c5
JL
285=item *
286
287L<Params::Check> has been upgraded from version 0.32 to 0.36.
288
95c6c5c5
JL
289=item *
290
291L<Parse::CPAN::Meta> has been upgraded from version 1.4402 to 1.4404.
292
95c6c5c5
JL
293=item *
294
295L<PerlIO::mmap> has been upgraded from version 0.010 to 0.011.
296
95c6c5c5
JL
297=item *
298
299L<PerlIO::via::QuotedPrint> has been upgraded from version 0.06 to 0.07.
300
95c6c5c5
JL
301=item *
302
99565752
NC
303L<Pod::Html> has been upgraded from version 1.15_02 to 1.16.
304
b1c9e38d 305The option C<--libpods> has been reinstated. It is deprecated, and its use
99565752
NC
306does nothing other than issue a warning that it is no longer supported.
307
954945b8
JL
308Since the HTML files generated by pod2html claim to have a UTF-8 charset,
309actually write the files out using UTF-8 [perl #111446].
7d101ed1 310
99565752
NC
311=item *
312
95c6c5c5 313L<POSIX> has been upgraded from version 1.30 to 1.31.
d9661073 314
95c6c5c5
JL
315=item *
316
317L<re> has been upgraded from version 0.19 to 0.20.
318
319See note about C<op_comp> in the L</Internal Changes> section below.
320
321=item *
322
323L<Safe> has been upgraded from version 2.31_01 to 2.33_01.
324
954945b8
JL
325Fix interactions with C<Devel::Cover>.
326
327Don't eval code under C<no strict>.
66aa79e2 328
3630f57e
CBW
329=item *
330
331L<Scalar::Util> has been upgraded from version 1.23 to version 1.25.
332
95c6c5c5
JL
333Fix an overloading issue with C<sum>.
334
335C<first> and C<reduce> now check the callback first (so C<&first(1)> is
336disallowed).
337
338Fix C<tainted> on magical values [rt.cpan.org #55763].
339
340Fix C<sum> on previously magical values [rt.cpan.org #61118].
341
342Fix reading past the end of a fixed buffer [rt.cpan.org #72700].
343
344=item *
345
346L<Search::Dict> has been upgraded from version 1.04 to 1.07.
347
348No longer require C<stat> on filehandles.
349
350Use C<fc> for casefolding.
351
352=item *
353
354L<Storable> has been upgraded from version 2.35 to 2.36.
355
95c6c5c5
JL
356=item *
357
358L<Term::ANSIColor> has been upgraded from version 3.01 to 3.02.
359
360Add support for italics.
361
362Improve error handling.
363
364=item *
365
366L<Test::Harness> has been upgraded from version 3.23 to 3.25.
367
368Fix glob semantics on Win32 [rt.cpan.org #49732].
369
954945b8 370Don't use C<Win32::GetShortPathName> when calling perl [rt.cpan.org #47890].
95c6c5c5
JL
371
372Ignore -T when reading shebang [rt.cpan.org #64404].
373
374Handle the case where we don't know the wait status of the test more
375gracefully.
376
954945b8 377Make the test summary 'ok' line overridable so that it can be changed to a
95c6c5c5
JL
378plugin to make the output of prove idempotent.
379
380Don't run world-writable files.
381
382=item *
383
384L<Unicode::UCD> has been upgraded from version 0.43 to 0.44.
385
386This adds a function L<all_casefolds()|Unicode::UCD/all_casefolds()>
387that returns all the casefolds.
388
61174fb5 389=back
f558db2f 390
61174fb5 391=head1 Documentation
80b8b050 392
61174fb5 393=head2 Changes to Existing Documentation
30608892 394
c7166200 395=head3 L<perlfaq>
ecd144ea 396
f9001595 397=over 4
05c8f9ed
RS
398
399=item *
400
954945b8 401L<perlfaq> has been synchronized with version 5.0150040 from CPAN.
9dea6244 402
204b72a4 403=back
9dea6244 404
7d101ed1
JL
405=head3 L<perlcheat>
406
407=over 4
408
409=item *
410
411L<perlcheat> has been reorganized, and a few new sections were added.
412
413=back
414
61174fb5 415=head1 Diagnostics
ef7131e9 416
4a301309
FC
417=head2 Removals of Diagnostics
418
419=over 4
420
a1d2df36
FC
421=item *
422
4a301309
FC
423The "Runaway prototype" warning that occurs in bizarre cases has been
424removed as being unhelpful and inconsistent.
425
8dffc0ab
FC
426=item *
427
428The "Not a format reference" error has been removed, as the only case in
429which it could be triggered was a bug.
430
dbc84d79
FC
431=item *
432
433The "Unable to create sub named %s" error has been removed for the same
434reason.
435
4a301309
FC
436=back
437
61174fb5 438=head1 Platform Support
05c8f9ed 439
61174fb5 440=head2 Platform-Specific Notes
ceb0881c 441
61174fb5 442=over 4
89cbc6b8 443
4aa4c0a5 444=item Win32
c6b15a5a 445
4aa4c0a5
TC
446C<link> on Win32 now attempts to set C<$!> to more appropriate values
447based on the Win32 API error code. [perl #112272]
c6b15a5a 448
0998713f
SH
449Perl no longer mangles the environment block, e.g. when launching a new
450sub-process, when the environment contains non-ASCII characters. Known
451problems still remain, however, when the environment contains characters
452outside of the current ANSI codepage (e.g. see the item about Unicode in
453C<%ENV> in L<http://perl5.git.perl.org/perl.git/blob/HEAD:/Porting/todo.pod>).
454[perl #113536]
455
112b6866
CB
456=item VMS
457
458All C header files from the top-level directory of the distribution are now
459installed on VMS, providing consistency with a long-standing practice on other
c7c2090d
JL
460platforms. Previously only a subset were installed, which broke non-core
461extension builds for extensions that depended on the missing include files.
112b6866 462
61174fb5 463=back
8e125188 464
61174fb5 465=head1 Internal Changes
8e125188 466
61174fb5 467=over 4
c4643160 468
422287bf
FC
469=item *
470
b7e9bef4
FC
471The C<study> function was made a no-op in 5.16. It was simply disabled via
472a C<return> statement; the code was left in place. Now the code supporting
473what C<study> used to do has been removed.
53de3ff0 474
f8ef51fd
FC
475=item *
476
477Under threaded perls, there is no longer a separate PV allocated for every
478COP to store its package name (C<< cop->stashpv >>). Instead, there is an
479offset (C<< cop->stashoff >>) into the new C<PL_stashpad> array, which
480holds stash pointers.
481
e128ab2c
DM
482=item *
483
484In the pluggable regex API, the C<regexp_engine> struct has acquired a new
485field C<op_comp>, which is currently just for perl's internal use, and
b1c9e38d 486should be initialised to NULL by other regex plugin modules.
e128ab2c 487
e2f0c3bb
FC
488=item *
489
490A new function C<alloccoptash> has been added to the API, but is considered
491experimental. See L<perlapi>.
492
61174fb5 493=back
422287bf 494
61174fb5 495=head1 Selected Bug Fixes
2de6ba8d 496
61174fb5 497=over 4
52c4b146 498
9aa9a888
KW
499=item *
500
e128ab2c 501The implementation of code blocks in regular expressions, such as C<(?{})>
954945b8 502and C<(??{})>, has been heavily reworked to eliminate a whole slew of bugs.
e128ab2c
DM
503The main user-visible changes are:
504
505=over 4
506
507=item *
508
509Code blocks within patterns are now parsed in the same pass as the
510surrounding code; in particular it is no longer necessary to have balanced
511braces: this now works:
512
513 /(?{ $x='{' })/
514
515This means that this error message is longer generated:
516
517 Sequence (?{...}) not terminated or not {}-balanced in regex
518
519but a new error may be seen:
520
521 Sequence (?{...}) not terminated with ')'
522
523In addition, literal code blocks within run-time patterns are only
524compiled once, at perl compile-time:
525
526 for my $p (...) {
527 # this 'FOO' block of code is compiled once,
528 # at the same time as the surrounding 'for' loop
529 /$p{(?{FOO;})/;
530 }
531
532=item *
533
534Lexical variables are now sane as regards scope, recursion and closure
954945b8 535behavior. In particular, C</A(?{B})C/> behaves (from a closure viewpoint)
e128ab2c
DM
536exactly like C</A/ && do { B } && /C/>, while C<qr/A(?{B})C/> is like
537C<sub {/A/ && do { B } && /C/}>. So this code now works how you might
be722aee 538expect, creating three regexes that match 0, 1, and 2:
e128ab2c
DM
539
540 for my $i (0..2) {
541 push @r, qr/^(??{$i})$/;
542 }
543 "1" =~ $r[1]; # matches
544
545=item *
546
b1c9e38d
JL
547The C<use re 'eval'> pragma is now only required for code blocks defined
548at runtime; in particular in the following, the text of the C<$r> pattern is
e128ab2c 549still interpolated into the new pattern and recompiled, but the individual
b1c9e38d 550compiled code-blocks within C<$r> are reused rather than being recompiled,
e128ab2c
DM
551and C<use re 'eval'> isn't needed any more:
552
553 my $r = qr/abc(?{....})def/;
554 /xyz$r/;
555
556=item *
557
558Flow control operators no longer crash. Each code block runs in a new
559dynamic scope, so C<next> etc. will not see any enclosing loops and
560C<caller> will not see any calling subroutines. C<return> returns a value
561from the code block, not from any enclosing subroutine.
562
563=item *
564
565Perl normally caches the compilation of run-time patterns, and doesn't
954945b8
JL
566recompile if the pattern hasn't changed, but this is now disabled if
567required for the correct behavior of closures. For example:
e128ab2c
DM
568
569 my $code = '(??{$x})';
570 for my $x (1..3) {
571 # recompile to see fresh value of $x each time
572 $x =~ /$code/;
573 }
574
575
576=item *
577
578The C</msix> and C<(?msix)> etc. flags are now propagated into the return
579value from C<(??{})>; this now works:
580
581 "AB" =~ /a(??{'b'})/i;
582
583=item *
584
585Warnings and errors will appear to come from the surrounding code (or for
586run-time code blocks, from an eval) rather than from an C<re_eval>:
587
588 use re 'eval'; $c = '(?{ warn "foo" })'; /$c/;
589 /(?{ warn "foo" })/;
590
591formerly gave:
592
593 foo at (re_eval 1) line 1.
594 foo at (re_eval 2) line 1.
595
596and now gives:
597
598 foo at (eval 1) line 1.
599 foo at /some/prog line 2.
600
601=back
602
603=item *
604
7ade940c
KW
605Perl now works as well as can be expected on all releases of Unicode so
606far. In v5.16, it worked on Unicodes 6.0 and 6.1, but there were
607various bugs for earlier releases; the older the release the more
608problems.
9aa9a888 609
701da2e9
FC
610=item *
611
612C<vec> no longer produces "uninitialized" warnings in lvalue context
613[perl #9423].
614
d67d4c0e
FC
615=item *
616
954945b8 617An optimization involving fixed strings in regular expressions could cause
d67d4c0e
FC
618a severe performance penalty in edge cases. This has been fixed
619[perl #76546].
620
b9dc63e8
FC
621=item *
622
7d101ed1
JL
623In certain cases, including empty subpatterns within a regular expression (such
624as C<(?:)> or C<(?:|)>) could disable some optimizations. This has been fixed.
625
626=item *
627
b9dc63e8 628The "Can't find an opnumber" message that C<prototype> produces when passed
954945b8 629a string like "CORE::nonexistent_keyword" now passes UTF-8 and embedded
18a66a2d 630NULs through unchanged [perl #97478].
b9dc63e8 631
b6d5888c
FC
632=item *
633
c0df136d
FC
634C<prototype> now treats magical variables like C<$1> the same way as
635non-magical variables when checking for the CORE:: prefix, instead of
636treating them as subroutine names.
637
638=item *
639
b1c9e38d 640Under threaded perls, a runtime code block in a regular expression could
b6d5888c
FC
641corrupt the package name stored in the op tree, resulting in bad reads
642in C<caller>, and possibly crashes [perl #113060].
643
d8816adc
FC
644=item *
645
646Referencing a closure prototype (C<\&{$_[1]}> in an attribute handler for a
647closure) no longer results in a copy of the subroutine (or assertion
648failures on debugging builds).
649
9b9df0bb
FC
650=item *
651
652C<eval '__PACKAGE__'> now returns the right answer on threaded builds if
653the current package has been assigned over (as in
654C<*ThisPackage:: = *ThatPackage::>) [perl #78742].
655
b16ca463
FC
656=item *
657
658If a package is deleted by code that it calls, it is possible for C<caller>
659to see a stack frame belonging to that deleted package. C<caller> could
660crash if the stash's memory address was reused for a scalar and a
661substitution was performed on the same scalar [perl #113486].
662
6fe02df8
FC
663=item *
664
665C<UNIVERSAL::can> no longer treats its first argument differently
666depending on whether it is a string or number internally.
667
2aab098d
FC
668=item *
669
954945b8
JL
670C<open> with C<< <& >> for the mode checks to see whether the third argument is
671a number, in determining whether to treat it as a file descriptor or a handle
672name. Magical variables like C<$1> were always failing the numeric check and
673being treated as handle names.
2aab098d 674
38d77b7f
FC
675=item *
676
677C<warn>'s handling of magical variables (C<$1>, ties) has undergone several
954945b8 678fixes. C<FETCH> is only called once now on a tied argument or a tied C<$@>
38d77b7f
FC
679[perl #97480]. Tied variables returning objects that stringify as "" are
680no longer ignored. A tied C<$@> that happened to return a reference the
681I<previous> time is was used is no longer ignored.
682
e811dbaa
FC
683=item *
684
8b9712e0
FC
685C<warn ""> now treats C<$@> with a number in it the same way, regardless of
686whether it happened via C<$@=3> or C<$@="3">. It used to ignore the
687former. Now it appends "\t...caught", as it has always done with
688C<$@="3">.
689
690=item *
691
e811dbaa 692Numeric operators on magical variables (e.g., S<C<$1 + 1>>) used to use
0998713f
SH
693floating point operations even where integer operations were more appropriate,
694resulting in loss of accuracy on 64-bit platforms [perl #109542].
e811dbaa 695
844115ec
FC
696=item *
697
698Unary negation no longer treats a string as a number if the string happened
b1c9e38d 699to be used as a number at some point. So, if C<$x> contains the string "dogs",
844115ec
FC
700C<-$x> returns "-dogs" even if C<$y=0+$x> has happened at some point.
701
a7143705
FC
702=item *
703
704In Perl 5.14, C<-'-10'> was fixed to return "10", not "+10". But magical
705variables (C<$1>, ties) were not fixed till now [perl #57706].
706
9c308096
FC
707=item *
708
709Unary negation now treats strings consistently, regardless of the internal
954945b8 710C<UTF8> flag.
9c308096 711
fc67deb3
KW
712=item *
713
714A regression introduced in Perl v5.16.0 involving
715C<tr/I<SEARCHLIST>/I<REPLACEMENTLIST>/> has been fixed. Only the first
716instance is supposed to be meaningful if a character appears more than
717once in C<I<SEARCHLIST>>. Under some circumstances, the final instance
718was overriding all earlier ones. [perl #113584]
719
45e0f58a
KW
720=item *
721
722Regular expressions like C<qr/\87/> previously silently inserted a NUL
723character, thus matching as if it had been written C<qr/\00087/>. Now it
b1c9e38d 724matches as if it had been written as C<qr/87/>, with a message that the
45e0f58a
KW
725sequence C<"\8"> is unrecognized.
726
e2f0c3bb
FC
727=item *
728
954945b8 729C<__SUB__> now works in special blocks (C<BEGIN>, C<END>, etc.).
e2f0c3bb
FC
730
731=item *
732
733Thread creation on Windows could theoretically result in a crash if done
954945b8 734inside a C<BEGIN> block. It still does not work properly, but it no longer
e2f0c3bb
FC
735crashes [perl #111610].
736
dbc84d79
FC
737=item *
738
739C<\&{''}> (with the empty string) now autovivifies a stub like any other
740sub name, and no longer produces the "Unable to create sub" error
741[perl #94476].
742
61174fb5 743=back
53de3ff0 744
233bba44
JL
745=head1 Known Problems
746
747=over 4
748
749=item *
750
954945b8 751On VMS, L<Module::Build> still fails its test suite.
233bba44
JL
752
753=item *
754
755On Win32, several tests fail intermittently, and may hang unless STDERR is
756redirected.
757
758=back
759
61174fb5 760=head1 Acknowledgements
d5dc7001 761
6c487cb9
JL
762Perl 5.17.1 represents approximately 4 weeks of development since Perl 5.17.0
763and contains approximately 37,000 lines of changes across 710 files from 35
764authors.
765
766Perl continues to flourish into its third decade thanks to a vibrant community
767of users and developers. The following people are known to have contributed the
768improvements that became Perl 5.17.1:
769
770?, Andy Dougherty, Aristotle Pagaltzis, Breno G. de Oliveira, Brian Fraser,
771Chris 'BinGOs' Williams, Craig A. Berry, David Mitchell, Dominic Hargreaves,
772Evan Miller, Father Chrysostomos, Florian Ragwitz, H.Merijn Brand, Herbert
773Breunung, Hugo van der Sanden, Jesse Luehrs, Karl Williamson, Karthik
774Rajagopalan, Lukas Mai, Martin Hasch, Michael Schroeder, Nicholas Clark, Paul
775Johnson, Reini Urban, Renee Baecker, Rhesa Rozendaal, Ricardo Signes, Shlomi
776Fish, Steve Hay, Steve Peters, Sullivan Beck, Tony Cook, Volker Schatz, Yves
777Orton, Zefram.
778
779The list above is almost certainly incomplete as it is automatically generated
780from version control history. In particular, it does not include the names of
781the (very much appreciated) contributors who reported issues to the Perl bug
782tracker.
783
784Many of the changes included in this version originated in the CPAN modules
785included in Perl's core. We're grateful to the entire CPAN community for
786helping Perl to flourish.
787
788For a more complete list of all of Perl's historical contributors, please see
789the F<AUTHORS> file in the Perl source distribution.
29cf780c 790
44691e6f
AB
791=head1 Reporting Bugs
792
793If you find what you think is a bug, you might check the articles
52deee2e 794recently posted to the comp.lang.perl.misc newsgroup and the perl
f9001595
RS
795bug database at http://rt.perl.org/perlbug/ . There may also be
796information at http://www.perl.org/ , the Perl Home Page.
44691e6f
AB
797
798If you believe you have an unreported bug, please run the L<perlbug>
52deee2e
DR
799program included with your release. Be sure to trim your bug down
800to a tiny but sufficient test case. Your bug report, along with the
801output of C<perl -V>, will be sent off to perlbug@perl.org to be
802analysed by the Perl porting team.
44691e6f
AB
803
804If the bug you are reporting has security implications, which make it
f9001595
RS
805inappropriate to send to a publicly archived mailing list, then please send
806it to perl5-security-report@perl.org. This points to a closed subscription
807unarchived mailing list, which includes
808all the core committers, who will be able
809to help assess the impact of issues, figure out a resolution, and help
810co-ordinate the release of patches to mitigate or fix the problem across all
811platforms on which Perl is supported. Please only use this address for
812security issues in the Perl core, not for modules independently
813distributed on CPAN.
44691e6f
AB
814
815=head1 SEE ALSO
816
52deee2e
DR
817The F<Changes> file for an explanation of how to view exhaustive details
818on what changed.
44691e6f
AB
819
820The F<INSTALL> file for how to build Perl.
821
822The F<README> file for general stuff.
823
824The F<Artistic> and F<Copying> files for copyright information.
825
826=cut