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Add more extensive information about @INC changes into perldelta (RT#131304)
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1=encoding utf8
2
3=head1 NAME
4
2c8edc25 5perldelta - what is new for perl v5.26.0
eabfc7bc 6
2cfe9b50 7=head1 DESCRIPTION
eabfc7bc 8
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9This document describes the differences between the 5.24.0 release and the
105.26.0 release.
11
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12=head1 Notice
13
14This release includes two updates with widespread effects:
15
16=over 4
17
18=item * C<.> no longer in C<@INC>
19
20The current modules, and for the execution of scripts. See the section
21L<<Removal of the current directory C<.> from @INC>> for the full details.
22
23=item * C<do> may now warn
24
25C<do> now gives a mandatory warning when it fails to load a file which it
26would have loaded had C<.> been in C<@INC>.
27
28=back
29
2c8edc25 30=head1 Core Enhancements
f3ed8cbf 31
2c8edc25 32=head2 New regular expression modifier C</xx>
f4b40f11 33
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34Specifying two C<x> characters to modify a regular expression pattern
35does everything that a single one does, but additionally TAB and SPACE
36characters within a bracketed character class are generally ignored and
37can be added to improve readability, like
38S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
39L<perlre/E<sol>x and E<sol>xx>.
5e50eae4 40
2c8edc25 41=head2 New Hash Function For 64-bit Builds
a049258c 42
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43We have switched to a hybrid hash function to better balance
44performance for short and long keys.
45
46For short keys, 16 bytes and under, we use an optimised variant of
47One At A Time Hard, and for longer keys we use Siphash 1-3. For very
48long keys this is a big improvement in performance. For shorter keys
49there is a modest improvement.
50
51=head2 Indented Here-documents
52
53This adds a new modifier '~' to here-docs that tells the parser
54that it should look for /^\s*$DELIM\n/ as the closing delimiter.
55
56These syntaxes are all supported:
57
58 <<~EOF;
59 <<~\EOF;
60 <<~'EOF';
61 <<~"EOF";
62 <<~`EOF`;
63 <<~ 'EOF';
64 <<~ "EOF";
65 <<~ `EOF`;
66
67The '~' modifier will strip, from each line in the here-doc, the
68same whitespace that appears before the delimiter.
69
70Newlines will be copied as is, and lines that don't include the
71proper beginning whitespace will cause perl to croak.
72
73For example:
74
75 if (1) {
76 print <<~EOF;
77 Hello there
78 EOF
79 }
80
81prints "Hello there\n" with no leading whitespace.
82
83=head2 '.' and @INC
84
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85Since time immemorial Perl has, as a last resort, loaded libraries
86from the current directory. For security reasons this is no longer the
87case, the C<@INC> variable no longer contains C<.> as its last element
88by default.
89
90If you want to disable this behavior at compile-time build perl with
91C<-Udefault_inc_excludes_dot> (C<-Ddefault_inc_excludes_dot> being the
92default now).
93
94If you'd like to add C<.> back to C<@INC> at runtime set
95C<PERL_USE_UNSAFE_INC=1> in the environment before starting
96perl. Setting it to 1 restores C<.> in the C<@INC> when perl otherwise
97lacks it.
98
99Various toolchain modules will set C<PERL_USE_UNSAFE_INC=1>
100themselves. E.g. L<Test::Harness> sets it since loading modules from a
101relative path is a common idiom in test code. If you find that you
102have C<.> in C<@INC> on a perl built with default settings it's likely
103that your code is being invoked by a toolchain module of some sort.
2c8edc25 104
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105=head2 create a safer utf8_hop() called utf8_hop_safe()
106
107Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after
108the end of the supplied buffer.
109
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110=head2 @{^CAPTURE}, %{^CAPTURE}, and %{^CAPTURE_ALL}
111
112C<@{^CAPTURE}> exposes the capture buffers of the last match as an
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113array. So C<$1> is C<${^CAPTURE}[0]>. This is a more efficient equivalent
114to code like C<substr($matched_string,$-[0],$+[0]-$-[0])>, and you don't
115have to keep track of the C<$matched_string> either. This variable has no
116single character equivalent. Note like the other regex magic variables
117the contents of this variable is dynamic, if you wish to store it beyond
118the lifetime of the match you must copy it to another array.
2c8edc25 119
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120C<%{^CAPTURE}> is the equivalent to C<%+> (ie named captures). Other than
121being more self documenting there is no difference between the two forms.
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122
123C<%{^CAPTURE_ALL}> is the equivalent to C<%-> (ie all named captures).
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124Other than being more self documenting there is no difference between the
125two forms.
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126
127=head2 Unicode 9.0 is now supported
128
129A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
130Modules that are shipped with core Perl but not maintained by p5p do not
131necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
132
133=head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
134
135Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and
136called it Script_Extensions (C<scx>). As of now, Perl uses this improved
137version when a property is specified as just C<\p{I<script>}>. The meaning of
138compound forms, like C<\p{sc=I<script>}> are unchanged. This should make
139programs be more accurate when determining if a character is used in a given
140script, but there is a slight chance of breakage for programs that very
141specifically needed the old behavior. See L<perlunicode/Scripts>.
142
143=head2 Declaring a reference to a variable
144
145As an experimental feature, Perl now allows the referencing operator to come
146after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
147L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
148be enabled with C<use feature 'declared_refs'>. It is experimental, and will
149warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
150It is intended mainly for use in assignments to references. For example:
151
152 use experimental 'refaliasing', 'declared_refs';
153 my \$a = \$b;
154
a9fbda47 155See L<perlref/Assigning to References> for more details.
a049258c 156
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157=head2 Perl can now do default collation in UTF-8 locales on platforms
158that support it
a049258c 159
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160Some platforms natively do a reasonable job of collating and sorting in
161UTF-8 locales. Perl now works with those. For portability and full
162control, L<Unicode::Collate> is still recommended, but now you may
163not need to do anything special to get good-enough results, depending on
164your application. See
165L<perllocale/Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>.
166
167=head2 Better locale collation of strings containing embedded C<NUL>
168characters
169
170In locales that have multi-level character weights, these are now
171ignored at the higher priority ones. There are still some gotchas in
172some strings, though. See
173L<perllocale/Collation of strings containing embedded C<NUL> characters>.
174
175=head2 Lexical subroutines are no longer experimental
176
2586f92e 177Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
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178code that disables the C<experimental::lexical_subs> warning category
179that the feature previously used will continue to work. The
180C<lexical_subs> feature has no effect; all Perl code can use lexical
181subroutines, regardless of what feature declarations are in scope.
182
183=head2 C<CORE> subroutines for hash and array functions callable via
184reference
185
186The hash and array functions in the C<CORE> namespace--C<keys>, C<each>,
187C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>--, can now
188be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference
e6abae1c 189(C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be
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190used when inlined.
191
192=head2 POSIX::tmpnam() has been removed
193
194The fundamentally unsafe C<tmpnam()> interface was deprecated in
195Perl 5.22.0 and has now been removed. In its place you can use
196for example the L<File::Temp> interfaces.
197
198=head2 require ::Foo::Bar is now illegal.
199
200Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
201bareword require which starts with a double colon dies instead.
202
203=head2 Unescaped literal C<"{"> characters in regular expression
204patterns are no longer permissible
205
206You have to now say something like C<"\{"> or C<"[{]"> to specify to
207match a LEFT CURLY BRACKET. This will allow future extensions to the
208language. This restriction is not enforced, nor are there current plans
209to enforce it, if the C<"{"> is the first character in the pattern.
210
211These have been deprecated since v5.16, with a deprecation message
212displayed starting in v5.22.
213
214=head2 Literal control character variable names are no longer permissible
215
216A variable name may no longer contain a literal control character under
217any circumstances. These previously were allowed in single-character
218names on ASCII platforms, but have been deprecated there since Perl
219v5.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
220control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
221source code.
222
223=head2 C<NBSP> is no longer permissible in C<\N{...}>
224
225The name of a character may no longer contain non-breaking spaces. It
226has been deprecated to do so since Perl v5.22.
a049258c 227
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228=head2 create a safer utf8_hop() called utf8_hop_safe()
229
230Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after
231the end of the supplied buffer.
232
a049258c
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233=head1 Security
234
89853d76 235=head2 Removal of the current directory (C<.>) from C<@INC>
2c8edc25 236
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237The perl binary includes a default set of paths in C<@INC>. Historically
238it has also included the current directory (C<.>) as the final entry,
239unless run with taint mode enabled (C<perl -T>). While convenient, this has
240security implications: for example, where a script attempts to load an
241optional module when its current directory is untrusted (such as F</tmp>),
242it could load and execute code from under that directory.
243
244Starting with v5.26.0, C<.> is always removed by default, not just under
245tainting. This has major implications for installing modules and executing
246scripts.
247
248The following new features have been added to help ameliorate these
249issues.
250
251=over
252
253=item * C<Configure -Udefault_inc_excludes_dot>
254
255There is a new C<Configure> option, C<default_inc_excludes_dot> (enabled
256by default) which builds a perl executable without C<.>; unsetting this
257option using C<-U> reverts perl to the old behaviour. This may fix your
258path issues but will reintroduce all the security concerns, so don't
259build a perl executable like this unless you're I<really> confident that
260such issues are not a concern in your environment.
261
262=item * C<$PERL_USE_UNSAFE_INC>
263
264There is a new environment variable recognised by the perl interpreter.
265If this variable has the value C<1> when the perl interpreter starts up,
266then C<.> will be automatically appended to C<@INC> (except under tainting).
267
268This allows you restore the old perl interpreter behaviour on a
269case-by-case basis. But note that this intended to be a temporary crutch,
270and this feature will likely be removed in some future perl version.
271It is currently set by the C<cpan> utility and C<Test::Harness> to
272ease installation of CPAN modules which have not been updated handle the
273lack of dot. Once again, don't use this unless you are sure that this
274will not reintroduce any security concerns.
275
276=item * A new mandatory warning issued by C<do>.
277
278While it is well-known that C<use> and C<require> use C<@INC> to search
279for the file to load, many people don't realise that C<do "file"> also
280searches C<@INC> if the file is a relative path. With the removal of C<.>,
281a simple C<do "file.pl"> will fail to read in and execute C<file.pl> from
282the current directory. Since this is commonly expected behaviour, a new
283mandatory warning is now issued whenever C<do> fails to load a file which
284it otherwise would have found if dot had been in C<@INC>.
285
286=back
287
288Here are some things script and module authors may need to do to make
289their software work in the new regime.
290
291=over
292
293=item * Script authors
294
295If the issue is within your own code (rather than within included
296modules), then you have two main options. Firstly, if you are confident
297that your script will only be run within a trusted directory (under which
298you expect to find trusted files and modules), then add C<.> back into the
299path; e.g.:
300
301 BEGIN {
302 my $dir = "/some/trusted/directory";
303 chdir $dir or die "Can't chdir to $dir: $!\n";
304 # safe now
305 push @INC, '.';
306 }
307 use "Foo::Bar"; # may load /some/trusted/directory/Foo/Bar.pm
308 do "config.pl"; # may load /some/trusted/directory/config.pl
309
310On the other hand, if your script is intended to be run from within
311untrusted directories (such as F</tmp>), then your script suddenly failing
312to load files may be indicative of a security issue. You most likely want
313to replace any relative paths with full paths; for example,
314
315 do ".foo_config.pl"
316
317might become
318
319 do "$ENV{HOME}/.foo_config.pl"
320
321If you are absolutely certain that you want your script to load and
322execute a file from the current directory, then use a C<./> prefix; for
323example:
324
325 do "./.foo_config.pl"
326
327=item * Installing and using CPAN modules
328
329If you install a CPAN module using an automatic tool like C<cpan>, then
330this tool will itself set the C<PERL_USE_UNSAFE_INC> environment variable
331while building and testing the module, which may be sufficient to install
332a distribution which hasn't been updated to be dot-aware. If you want to
333install such a module manually, then you'll need to replace the
334traditional invocation:
335
336 perl Makefile.PL && make && make test && make install
337
338with something like
339
340 (export PERL_USE_UNSAFE_INC=1; \
341 perl Makefile.PL && make && make test && make install)
342
343Note that this only helps build and install an unfixed module. It's
344possible for the tests to pass (since they were run under
345C<PERL_USE_UNSAFE_INC=1>), but for the module itself to fail to perform
346correctly in production. In this case you may have to temporarily modify
347your script until such time as fixed version of the module is released.
348For example:
349
350 use Foo::Bar;
351 {
352 local @INC = (@INC, '.');
353 # assuming read_config() needs '.' in @INC
354 $config = Foo::Bar->read_config();
355 }
356
357This is only rarely expected to be necessary. Again, if doing this,
358assess the resultant risks first.
359
360=item * Module Authors
361
362If you maintain a CPAN distribution, it may need updating to run in
363a dotless environment. Although C<cpan> and other such tools will
364currently set the C<PERL_USE_UNSAFE_INC> during module build, this is
365temporary workaround for the set of modules which rely on C<.> being in
366C<@INC> for installation and testing, and this may mask deeper issues. It
367could result in a module which passes tests and installs, but which
368fails at run time.
369
370During build, test and install, it will normally be the case that any perl
371processes will be executing directly within the root directory of the
372untarred distribution, or a known subdirectory of that, such as F<t/>. It
373may well be that F<Makefile.PL> or F<t/foo.t> will attempt to include
374local modules and configuration files using their direct relative
375filenames, which will now fail.
376
377However, as described above, automatic tools like F<cpan> will (for now)
378set the C<PERL_USE_UNSAFE_INC> environment variable, which introduces
379dot during build.
380
381This makes it likely that your existing build and test code will work, but
382this may mask issues with your code which only manifest when used after
383install. It is prudent to try and run your build process with that
384variable explicitly disabled:
385 (export PERL_USE_UNSAFE_INC=0; \
386 perl Makefile.PL && make && make test && make install)
387
388This is more likely to show up any potential problems with your module's
389build process, or even with the module itself. Fixing such issues will
390ensure both that your module can again be installed manually, and that
391it will still build once the C<PERL_USE_UNSAFE_INC> crutch goes away.
392
393When fixing issues in tests due to the removal of dot from C<@INC>,
394reinsertion of dot into C<@INC> should be performed with caution, for this
395too may suppress real errors in your runtime code. You are encouraged
396wherever possible to apply the aforementioned approaches with explicit
397absolute/relative paths, or relocate your needed files into a subdirectory
398and insert that subdirectory into C<@INC> instead.
399
400If your runtime code has problems under the dotless C<@INC>, then the comments
401above on how to fix for script authors will mostly apply here too. Bear in
402mind though that it is considered bad form for a module to globally add dot to
403C<@INC>, since it introduces both a security risk and hides issues of
404accidentally requiring dot in C<@INC>, as explained above.
405
406=back
407>>>>>>> Add more extensive information about @INC changes into perldelta (RT#131304)
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408
409=head2 "Escaped" colons and relative paths in PATH
410
411On Unix systems, Perl treats any relative paths in the PATH environment
412variable as tainted when starting a new process. Previously, it was
413allowing a backslash to escape a colon (unlike the OS), consequently
414allowing relative paths to be considered safe if the PATH was set to
415something like C</\:.>. The check has been fixed to treat C<.> as tainted
416in that example.
417
418=head2 C<-Di> switch is now required for PerlIO debugging output
419
420Previously PerlIO debugging output would be sent to the file specified
421by the C<PERLIO_DEBUG> environment variable if perl wasn't running
422setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
423
424If perl performed output at a point where it hadn't yet parsed its
425switches this could result in perl creating or overwriting the file
426named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
427
428Perl now requires the C<-Di> switch to produce PerlIO debugging
429output. By default this is written to C<stderr>, but can optionally
430be redirected to a file by setting the C<PERLIO_DEBUG> environment
431variable.
a049258c 432
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433If perl is running setuid or the C<-T> switch has supplied
434C<PERLIO_DEBUG> is ignored and the debugging output is sent to
435C<stderr> as for any other C<-D> switch.
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436
437=head1 Incompatible Changes
438
2c8edc25 439=head2 C<${^ENCODING}> has been removed
a049258c 440
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441Consequently, the L<encoding> pragma's default mode is no longer supported. If
442you still need to write your source code in encodings other than UTF-8, use a
443source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
444option.
a049258c 445
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446=head2 C<scalar(%hash)> return signature changed
447
448The value returned for C<scalar(%hash)> will no longer show information about
449the buckets allocated in the hash. It will simply return the count of used
450keys. It is thus equivalent to C<0+keys(%hash)>.
451
452A form of backwards compatibility is provided via C<Hash::Util::bucket_ratio()>
453which provides the same behavior as C<scalar(%hash)> provided prior to Perl
4545.25.
455
456=head2 C<keys> returned from an lvalue subroutine
457
458C<keys> returned from an lvalue subroutine can no longer be assigned
459to in list context.
460
461 sub foo : lvalue { keys(%INC) }
462 (foo) = 3; # death
463 sub bar : lvalue { keys(@_) }
464 (bar) = 3; # also an error
465
466This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
467C<(keys @_) = ...>, which are also errors. [perl #128187]
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468
469=head1 Deprecations
470
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471=head2 String delimiters that aren't stand-alone graphemes are now deprecated
472
473In order for Perl to eventually allow string delimiters to be Unicode
474grapheme clusters (which look like a single character, but may be
475a sequence of several ones), we have to stop allowing a single char
476delimiter that isn't a grapheme by itself. These are unlikely to exist
477in actual code, as they would typically display as attached to the
478character in front of them.
479
480=head1 Performance Enhancements
a049258c 481
2c8edc25 482=over 4
a049258c 483
2c8edc25 484=item *
a049258c 485
2c8edc25 486A hash in boolean context is now sometimes faster, e.g.
a049258c 487
2c8edc25 488 if (!%h) { ... }
a049258c 489
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490This was already special-cased, but some cases were missed, and even the
491ones which weren't have been improved.
a049258c 492
2c8edc25 493=item *
a049258c 494
2c8edc25 495Several other ops may now also be faster in boolean context.
a049258c 496
2c8edc25 497=item * New Faster Hash Function on 64 bit builds
a049258c 498
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499We use a different hash function for short and long keys. This should
500improve performance and security, especially for long keys.
a049258c 501
2c8edc25 502=item * readline is faster
a049258c 503
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504Reading from a file line-by-line with C<readline()> or C<< E<lt>E<gt> >> should
505now typically be faster due to a better implementation of the code that
506searches for the next newline character.
507
508=item *
a049258c 509
2c8edc25 510Reduce cost of SvVALID().
a049258c 511
2c8edc25 512=item *
ad5c8857 513
2c8edc25 514C<$ref1 = $ref2> has been optimized.
5e50eae4 515
4b99a68c 516=item *
f4b40f11 517
2c8edc25 518Array and hash assignment are now faster, e.g.
ec34c8a4 519
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520 (..., @a) = (...);
521 (..., %h) = (...);
f4b40f11 522
2c8edc25 523especially when the RHS is empty.
ec34c8a4 524
2c8edc25 525=item *
a049258c 526
2c8edc25 527Reduce the number of odd special cases for the C<SvSCREAM> flag.
e770df11 528
2c8edc25 529=item *
a049258c 530
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531Avoid sv_catpvn() in do_vop() when unneeded.
532
533=item *
534
535Enhancements in Regex concat COW implementation.
536
537=item *
538
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539Clearing hashes and arrays has been made slightly faster. Now code
540like this is around 5% faster:
541
542 my @a;
543 for my $i (1..3_000_000) {
544 @a = (1,2,3);
545 @a = ();
546 }
547
548and this code around 3% faster:
549
550 my %h;
551 for my $i (1..3_000_000) {
552 %h = qw(a 1 b 2);
553 %h = ();
554 }
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555
556=item *
557
558Better optimise array and hash assignment
559
560=item *
561
562Converting a single-digit string to a number is now substantially faster.
563
564=item *
565
566The internal op implementing the C<split> builtin has been simplified and
567sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
568to do its work. Secondly, code of the form C<my @x = split(...)> is now
569optimised in the same way as C<@x = split(...)>, and is therefore a few
570percent faster.
571
572=item *
573
574The rather slow implementation for the experimental subroutine signatures
575feature has been made much faster; it is now comparable in speed with the
576old-style C<my ($a, $b, @c) = @_>.
7ca0bfc4 577
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578=item *
579
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580Bareword constant strings are now permitted to take part in constant
581folding. They were originally exempted from constant folding in August 1999,
582during the development of Perl 5.6, to ensure that C<use strict "subs">
583would still apply to bareword constants. That has now been accomplished a
584different way, so barewords, like other constants, now gain the performance
585benefits of constant folding.
586
587This also means that void-context warnings on constant expressions of
588barewords now report the folded constant operand, rather than the operation;
589this matches the behaviour for non-bareword constants.
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590
591=back
592
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593=head1 Modules and Pragmata
594
a049258c
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595=head2 Updated Modules and Pragmata
596
597=over 4
fbe3f407 598
759020c9 599=item *
7ca0bfc4 600
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601L<Archive::Tar> has been upgraded from version 2.04 to 2.24.
602
603=item *
604
605L<arybase> has been upgraded from version 0.11 to 0.12.
606
607=item *
608
609L<attributes> has been upgraded from version 0.27 to 0.29.
a049258c 610
2c8edc25
S
611The deprecation message for the C<:unique> and C<:locked> attributes
612now mention they will disappear in Perl 5.28.
a049258c 613
2c8edc25 614=item *
a049258c 615
0cc8c746
S
616L<B> has been upgraded from version 1.62 to 1.68.
617
618=item *
619
620L<B::Concise> has been upgraded from version 0.996 to 0.999.
2c8edc25
S
621
622Its output is now more descriptive for C<op_private> flags.
d5c7a4fc 623
759020c9
S
624=item *
625
0cc8c746
S
626L<B::Debug> has been upgraded from version 1.23 to 1.24.
627
628=item *
629
630L<B::Deparse> has been upgraded from version 1.37 to 1.40.
631
632=item *
633
2c8edc25 634L<B::Xref> has been upgraded from version 1.05 to 1.06.
a049258c 635
2c8edc25 636It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 637
2c8edc25 638=item *
a049258c 639
0cc8c746
S
640L<base> has been upgraded from version 2.23 to 2.25.
641
642=item *
643
644L<bignum> has been upgraded from version 0.42 to 0.47.
645
646=item *
647
648L<Carp> has been upgraded from version 1.40 to 1.42.
649
650=item *
651
652L<charnames> has been upgraded from version 1.43 to 1.44.
653
654=item *
655
656L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.074.
657
658=item *
659
660L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.074.
661
662=item *
663
664L<Config::Perl::V> has been upgraded from version 0.25 to 0.28.
665
666=item *
667
668L<CPAN> has been upgraded from version 2.11 to 2.18.
669
670=item *
671
672L<CPAN::Meta> has been upgraded from version 2.150005 to 2.150010.
673
674=item *
675
676L<Data::Dumper> has been upgraded from version 2.160 to 2.167.
a049258c 677
2c8edc25 678The XS implementation now supports Deparse.
a049258c 679
2c8edc25 680This fixes a stack management bug. [perl #130487].
a049258c 681
2c8edc25 682=item *
a049258c 683
0cc8c746
S
684L<DB_File> has been upgraded from version 1.835 to 1.840.
685
686=item *
687
688L<Devel::Peek> has been upgraded from version 1.23 to 1.26.
689
690=item *
691
692L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
693
694=item *
695
2c8edc25 696L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
a049258c 697
2c8edc25 698It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 699
2c8edc25 700=item *
a049258c 701
0cc8c746 702L<diagnostics> has been upgraded from version 1.34 to 1.36.
a049258c 703
2c8edc25 704It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
7ca0bfc4 705
ad5c8857 706=item *
7ca0bfc4 707
0cc8c746
S
708L<Digest> has been upgraded from version 1.17 to 1.17_01.
709
710=item *
711
712L<Digest::MD5> has been upgraded from version 2.54 to 2.55.
713
714=item *
715
716L<Digest::SHA> has been upgraded from version 5.95 to 5.96.
717
718=item *
719
720L<DynaLoader> has been upgraded from version 1.38 to 1.42.
721
722=item *
723
724L<Encode> has been upgraded from version 2.80 to 2.88.
725
726=item *
727
728L<encoding> has been upgraded from version 2.17 to 2.19.
8f7edc68 729
2c8edc25
S
730This module's default mode is no longer supported as of Perl 5.25.3. It now
731dies when imported, unless the C<Filter> option is being used.
d5c7a4fc 732
2c8edc25 733=item *
d5c7a4fc 734
2c8edc25 735L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
a049258c 736
2c8edc25
S
737This module is no longer supported as of Perl 5.25.3. It emits a warning to
738that effect and then does nothing.
a049258c 739
2c8edc25 740=item *
d5c7a4fc 741
0cc8c746 742L<Errno> has been upgraded from version 1.25 to 1.28.
a049258c 743
2c8edc25 744Document that using C<%!> loads Errno for you.
d5c7a4fc 745
2c8edc25 746It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
3abe9611 747
c714fb1f 748=item *
3ce6a296 749
2c8edc25 750L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
a049258c 751
2c8edc25 752It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 753
2c8edc25 754=item *
a049258c 755
0cc8c746
S
756L<ExtUtils::MakeMaker> has been upgraded from version 7.10_01 to 7.24.
757
758=item *
759
760L<ExtUtils::Miniperl> has been upgraded from version 1.05 to 1.06.
761
762=item *
763
764L<ExtUtils::ParseXS> has been upgraded from version 3.31 to 3.34.
765
766=item *
767
768L<ExtUtils::Typemaps> has been upgraded from version 3.31 to 3.34.
769
770=item *
771
772L<feature> has been upgraded from version 1.42 to 1.47.
2c8edc25
S
773
774Fixes the Unicode Bug in the range operator.
a049258c
S
775
776=item *
5c92a635 777
0cc8c746
S
778L<File::Copy> has been upgraded from version 2.31 to 2.32.
779
780=item *
781
782L<File::Fetch> has been upgraded from version 0.48 to 0.52.
783
784=item *
785
786L<File::Glob> has been upgraded from version 1.26 to 1.28.
d5c7a4fc 787
2c8edc25 788Issue a deprecation message for C<File::Glob::glob()>.
d5c7a4fc 789
2c8edc25 790=item *
d5c7a4fc 791
0cc8c746
S
792L<File::Spec> has been upgraded from version 3.63 to 3.67.
793
794=item *
795
796L<FileHandle> has been upgraded from version 2.02 to 2.03.
797
798=item *
799
2c8edc25 800L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
a049258c 801
2c8edc25
S
802It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
803end-of-file. [perl #107726]
64afbd29
DM
804
805=item *
806
0cc8c746
S
807L<Getopt::Long> has been upgraded from version 2.48 to 2.49.
808
809=item *
810
811L<Getopt::Std> has been upgraded from version 1.11 to 1.12.
812
813=item *
814
815L<Hash::Util> has been upgraded from version 0.19 to 0.22.
816
817=item *
818
819L<HTTP::Tiny> has been upgraded from version 0.056 to 0.070.
a049258c 820
2c8edc25 821Internal 599-series errors now include the redirect history.
a049258c 822
2c8edc25 823=item *
a049258c 824
0cc8c746 825L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
a049258c 826
2c8edc25 827It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 828
2c8edc25 829=item *
a049258c 830
0cc8c746
S
831L<IO> has been upgraded from version 1.36 to 1.38.
832
833=item *
834
601d9a87 835IO-Compress has been upgraded from version 2.069 to 2.074.
0cc8c746
S
836
837=item *
838
839L<IO::Socket::IP> has been upgraded from version 0.37 to 0.38.
840
841=item *
842
843L<IPC::Cmd> has been upgraded from version 0.92 to 0.96.
844
845=item *
846
847L<IPC::SysV> has been upgraded from version 2.06_01 to 2.07.
848
849=item *
850
851L<JSON::PP> has been upgraded from version 2.27300 to 2.27400_02.
852
853=item *
854
2c8edc25
S
855L<lib> has been upgraded from version 0.63 to 0.64.
856
857It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
faab9793 858
c714fb1f 859=item *
ad5c8857 860
0cc8c746
S
861L<List::Util> has been upgraded from version 1.42_02 to 1.46_02.
862
863=item *
864
865L<Locale::Codes> has been upgraded from version 3.37 to 3.42.
866
867=item *
868
869L<Locale::Maketext> has been upgraded from version 1.26 to 1.28.
870
871=item *
872
873L<Locale::Maketext::Simple> has been upgraded from version 0.21 to 0.21_01.
874
875=item *
876
877L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
ad5c8857 878
2c8edc25 879There have also been some core customizations.
ad5c8857 880
2c8edc25 881=item *
2e0dcc12 882
0cc8c746
S
883L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
884
885=item *
886
887L<Math::BigRat> has been upgraded from version 0.260802 to 0.2611.
888
889=item *
890
891L<Math::Complex> has been upgraded from version 1.59 to 1.5901.
892
893=item *
894
895L<Memoize> has been upgraded from version 1.03 to 1.03_01.
896
897=item *
898
899L<Module::CoreList> has been upgraded from version 5.20170420 to 5.20170520.
900
901=item *
902
903L<Module::Load::Conditional> has been upgraded from version 0.64 to 0.68.
904
905=item *
906
907L<Module::Metadata> has been upgraded from version 1.000031 to 1.000033.
908
909=item *
910
911L<mro> has been upgraded from version 1.18 to 1.20.
912
913=item *
914
915L<Net::Ping> has been upgraded from version 2.43 to 2.55.
d5c7a4fc 916
2c8edc25
S
917IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
918other enhancements.
d5c7a4fc 919
2c8edc25
S
920Remove sudo from 500_ping_icmp.t.
921
922Avoid stderr noise in tests
923
924Check for echo in new Net::Ping tests.
d5c7a4fc 925
a049258c 926=item *
d5c7a4fc 927
0cc8c746
S
928L<NEXT> has been upgraded from version 0.65 to 0.67.
929
930=item *
931
932L<Opcode> has been upgraded from version 1.34 to 1.39.
933
934=item *
935
936L<open> has been upgraded from version 1.10 to 1.11.
937
938=item *
939
2c8edc25 940L<OS2::Process> has been upgraded from version 1.11 to 1.12.
a049258c 941
2c8edc25 942It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 943
2c8edc25 944=item *
a049258c 945
2c8edc25 946L<overload> has been upgraded from version 1.26 to 1.28.
a049258c 947
2c8edc25 948Its compilation speed has been improved slightly.
a049258c 949
2c8edc25
S
950=item *
951
0cc8c746
S
952L<parent> has been upgraded from version 0.234 to 0.236.
953
954=item *
955
2c8edc25
S
956L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
957
958Ignore F</dev/tty> on non-Unix systems. [perl #113960]
959
960=item *
961
0cc8c746
S
962L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
963
964=item *
965
966L<perlfaq> has been upgraded from version 5.021010 to 5.021011.
967
968=item *
969
970L<PerlIO> has been upgraded from version 1.09 to 1.10.
971
972=item *
973
974L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
975
976=item *
977
978L<PerlIO::scalar> has been upgraded from version 0.24 to 0.26.
979
980=item *
981
982L<Pod::Checker> has been upgraded from version 1.60 to 1.73.
983
984=item *
985
986L<Pod::Functions> has been upgraded from version 1.10 to 1.11.
987
988=item *
989
990L<Pod::Html> has been upgraded from version 1.22 to 1.2202.
991
992=item *
993
994L<Pod::Perldoc> has been upgraded from version 3.25_02 to 3.28.
995
996=item *
997
998L<Pod::Simple> has been upgraded from version 3.32 to 3.35.
999
1000=item *
1001
1002L<Pod::Usage> has been upgraded from version 1.68 to 1.69.
1003
1004=item *
1005
1006L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
2c8edc25
S
1007defects in making its symbols exportable. [perl #127821]
1008The C<POSIX::tmpnam()> interface has been removed,
1009see L</"POSIX::tmpnam() has been removed">.
1010Trying to import POSIX subs that have no real implementations
1011(like C<POSIX::atend()>) now fails at import time, instead of
1012waiting until runtime.
1013
1014=item *
1015
0cc8c746 1016L<re> has been upgraded from version 0.32 to 0.34
2c8edc25
S
1017
1018This adds support for the new L<C<E<47>xx>|perlre/E<sol>x and E<sol>xx>
1019regular expression pattern modifier, and a change to the L<S<C<use re
1020'strict'>>|re/'strict' mode> experimental feature. When S<C<re
1021'strict'>> is enabled, a warning now will be generated for all
1022unescaped uses of the two characters C<}> and C<]> in regular
1023expression patterns (outside bracketed character classes) that are taken
1024literally. This brings them more in line with the C<)> character which
1025is always a metacharacter unless escaped. Being a metacharacter only
1026sometimes, depending on action at a distance, can lead to silently
1027having the pattern mean something quite different than was intended,
1028which the S<C<re 'strict'>> mode is intended to minimize.
1029
1030=item *
1031
0cc8c746
S
1032L<Safe> has been upgraded from version 2.39 to 2.40.
1033
1034=item *
1035
1036L<Scalar::Util> has been upgraded from version 1.42_02 to 1.46_02.
1037
1038=item *
1039
1040L<Storable> has been upgraded from version 2.56 to 2.62.
2c8edc25
S
1041
1042Fixes [perl #130098].
1043
1044=item *
1045
0cc8c746
S
1046L<Symbol> has been upgraded from version 1.07 to 1.08.
1047
1048=item *
1049
1050L<Sys::Syslog> has been upgraded from version 0.33 to 0.35.
1051
1052=item *
1053
1054L<Term::ANSIColor> has been upgraded from version 4.04 to 4.06.
1055
1056=item *
1057
2c8edc25
S
1058L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
1059
1060It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1061
1062=item *
1063
0cc8c746 1064L<Test> has been upgraded from version 1.28 to 1.30.
2c8edc25
S
1065
1066It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1067
1068=item *
1069
0cc8c746
S
1070L<Test::Harness> has been upgraded from version 3.36 to 3.38.
1071
1072=item *
1073
1074L<Test::Simple> has been upgraded from version 1.001014 to 1.302073.
1075
1076=item *
1077
1078L<Thread::Queue> has been upgraded from version 3.09 to 3.12.
1079
1080=item *
1081
2c8edc25
S
1082L<Thread::Semaphore> has been upgraded from 2.12 to 2.13.
1083
1084Added the C<down_timed> method.
1085
1086=item *
1087
0cc8c746 1088L<threads> has been upgraded from version 2.07 to 2.15.
2c8edc25
S
1089
1090Compatibility with 5.8 has been restored.
1091
1092Fixes [perl #130469].
1093
1094=item *
1095
0cc8c746 1096L<threads::shared> has been upgraded from version 1.51 to 1.56.
2c8edc25
S
1097
1098This fixes [cpan #119529], [perl #130457]
1099
1100=item *
1101
0cc8c746
S
1102L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
1103
1104=item *
1105
1106L<Time::HiRes> has been upgraded from version 1.9733 to 1.9741.
2c8edc25
S
1107
1108It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
11093.9).
1110
1111Now uses C<clockid_t>.
1112
1113=item *
1114
0cc8c746
S
1115L<Time::Local> has been upgraded from version 1.2300 to 1.25.
1116
1117=item *
1118
1119L<Unicode::Collate> has been upgraded from version 1.14 to 1.19.
1120
1121=item *
1122
1123L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
2c8edc25
S
1124
1125It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1126
1127=item *
1128
0cc8c746
S
1129L<version> has been upgraded from version 0.9916 to 0.9917.
1130
1131=item *
1132
1133L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
2c8edc25
S
1134
1135It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1136
1137=item *
1138
0cc8c746
S
1139L<warnings> has been upgraded from version 1.36 to 1.37.
1140
1141=item *
1142
1143L<XS::Typemap> has been upgraded from version 0.14 to 0.15.
1144
1145=item *
1146
1147L<XSLoader> has been upgraded from version 0.21 to 0.27.
2c8edc25
S
1148
1149Fixed a security hole in which binary files could be loaded from a path
1150outside of L<C<@INC>|perlvar/@INC>.
1151
1152It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1153
1154=back
1155
2c8edc25
S
1156=head1 Documentation
1157
1158=head2 New Documentation
a049258c 1159
2c8edc25 1160=head3 L<perldeprecation>
a049258c 1161
2c8edc25
S
1162This file documents all upcoming deprecations, and some of the deprecations
1163which already have been removed. The purpose of this documentation is
1164two-fold: document what will disappear, and by which version, and serve
1165as a guide for people dealing with code which has features that no longer
1166work after an upgrade of their perl.
a049258c 1167
2c8edc25 1168=head2 Changes to Existing Documentation
a049258c 1169
2c8edc25 1170=head3 L<perlcall>
a049258c
S
1171
1172=over 4
1173
2c8edc25
S
1174=item *
1175
1176Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30
a049258c 1177
2c8edc25
S
1178This was changed to drop a leading C<v> in C<v5.30>, so it uses the same
1179style as other deprecation messages.
a049258c 1180
2c8edc25
S
1181=item *
1182
1183"\c%c" is more clearly written simply as "%s".
1184
1185It was decided to undeprecate the use of C<\c%c>, see L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>
1186
1187=item *
1188
1189Removed redundant C<dSP> from an example.
a049258c 1190
2c8edc25 1191=back
a049258c 1192
2c8edc25 1193=head3 L<perlcommunity>
a049258c
S
1194
1195=over 4
1196
2c8edc25 1197=item *
a049258c 1198
2c8edc25 1199All references to Usenet have been removed.
a049258c
S
1200
1201=back
1202
2c8edc25
S
1203=head3 L<perldata>
1204
1205=over 4
1206
1207=item *
1208
1209Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
1210signature changed> above.
1211
1212=item *
a049258c 1213
2c8edc25
S
1214Use of single character variables, with the variable name a non printable
1215character in the range C<\x80>-C<\xFF> is no longer allowed. Update the docs to
1216reflect this.
1217
1218=back
1219
1220=head3 L<perldelta>
a049258c
S
1221
1222=over 4
1223
2c8edc25 1224=item *
a049258c 1225
2c8edc25 1226All references to Usenet have been removed.
a049258c
S
1227
1228=back
1229
2c8edc25
S
1230=head3 L<perldiag>
1231
1232=over 4
1233
1234=item *
1235
1236Deprecations are to be marked with a D.
1237C<"%s() is deprecated on :utf8 handles"> use a deprecation message, and as
1238such, such be marked C<"(D deprecated)"> and not C<"(W deprecated)">.
a049258c 1239
2c8edc25 1240=back
a049258c 1241
2c8edc25 1242=head3 L<perlexperiment>
a049258c
S
1243
1244=over 4
1245
1246=item *
1247
2c8edc25 1248Documented new feature: See L</Declaring a reference to a variable> above.
a049258c
S
1249
1250=back
1251
2c8edc25
S
1252=head3 L<perlfunc>
1253
1254=over 4
1255
1256=item *
1257
1258Defined on aggregates is no longer allowed. Perlfunc was still reporting it as
1259deprecated, and that it will be deleted in the future.
1260
1261=item *
1262
1263Clarified documentation of L<C<seek()>|perlfunc/seek>,
1264L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>.
1265L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
a049258c 1266
2c8edc25
S
1267=item *
1268
1269Removed obsolete documentation of L<C<study()>|perlfunc/study>.
1270
1271=back
a049258c 1272
2c8edc25 1273=head3 L<perlguts>
a049258c
S
1274
1275=over 4
1276
1277=item *
1278
2c8edc25 1279Add C<pTHX_> to magic method examples.
a049258c
S
1280
1281=back
1282
2c8edc25
S
1283=head3 L<perlhack>
1284
1285=over 4
1286
1287=item *
1288
1289Document Tab VS Space.
a049258c 1290
2c8edc25 1291=back
a049258c 1292
2c8edc25 1293=head3 L<perlinterp>
a049258c
S
1294
1295=over 4
1296
1297=item *
1298
2c8edc25
S
1299L<perlinterp> has been expanded to give a more detailed example of how to
1300hunt around in the parser for how a given operator is handled.
a049258c
S
1301
1302=back
1303
2c8edc25 1304=head3 L<perllocale>
a049258c
S
1305
1306=over 4
1307
1308=item *
1309
2c8edc25
S
1310Document C<NUL> collation handling.
1311
1312=item *
1313
1314Some locales aren't compatible with Perl. Note the potential bad
1315consequences of using them.
a049258c
S
1316
1317=back
1318
2c8edc25
S
1319=head3 L<perlmodinstall>
1320
1321=over 4
1322
1323=item *
1324
1325All references to Usenet have been removed.
1326
1327=back
1328
1329=head3 L<perlmodlib>
1330
1331=over 4
1332
1333=item *
1334
1335Updated the mirror list.
1336
1337=item *
1338
1339All references to Usenet have been removed.
1340
1341=back
1342
1343=head3 L<perlnewmod>
1344
1345=over 4
1346
1347=item *
1348
1349All references to Usenet have been removed.
1350
1351=back
1352
1353=head3 L<perlobj>
1354
1355=over 4
1356
1357=item *
1358
1359Added a section on calling methods using their fully qualified names.
1360
1361=item *
1362
1363Do not discourage manual @ISA.
1364
1365=back
1366
1367=head3 L<perlootut>
1368
1369=over 4
1370
1371=item *
1372
1373Tidy the document.
1374
1375=item *
1376
1377Mention C<Moo> more.
1378
1379=back
1380
1381=head3 L<perlop>
1382
1383=over 4
1384
1385=item *
1386
1387Clarify behavior single quote regexps.
1388
1389=back
1390
1391=head3 L<perlre>
1392
1393=over 4
1394
1395=item *
1396
1397Several minor enhancements to the documentation.
1398
1399=back
1400
1401=head3 L<perlsec>
1402
1403=over 4
1404
1405=item *
1406
1407Fixed link to Crosby paper on hash complexity attack.
1408
1409=back
1410
1411=head3 L<perlref>
1412
1413=over 4
1414
1415=item *
1416
1417Documented new feature: See L</Declaring a reference to a variable> above.
1418
1419=back
1420
1421=head3 L<perltie>
1422
1423=over 4
1424
1425=item *
1426
1427Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
1428signature changed> above.
1429
1430=back
1431
1432=head3 L<perlunicode>
1433
1434=over 4
1435
1436=item *
1437
1438Documented change to C<\p{I<script>}> to now use the improved Script_Extensions
1439property. See L</Use of \p{script} uses the improved Script_Extensions
1440property> above.
1441
1442=item *
1443
1444Updated the text to correspond with changes in Unicode UTS#18, concerning
1445regular expressions, and Perl compatibility with what it says.
1446
1447=back
1448
1449=head3 L<perlvar>
1450
1451=over 4
1452
1453=item *
1454
1455Removed obsolete documentation of C<${^ENCODING}>. See L</${^ENCODING} has
1456been removed> above.
1457
1458=item *
1459
1460Document C<@ISA>. Was documented other places, not not in L<perlvar>.
1461
1462=back
1463
1464=head1 Diagnostics
1465
1466=head2 New Diagnostics
1467
1468=head3 New Errors
1469
1470=over 4
1471
1472=item *
1473
1474Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1475a warning recommending to fix the C<do> statement:
1476
1477L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
1478
1479=item *
1480
1481Using the empty pattern (which re-executes the last successfully-matched
1482pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
4f73c567
S
1483always previously yielded a segfault. It now produces an error:
1484L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
2c8edc25
S
1485
1486=item *
1487
1488L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
1489
1490(F) To declare references to variables, as in C<my \%x>, you must first enable
1491the feature:
1492
1493 no warnings "experimental::declared_refs";
1494 use feature "declared_refs";
1495
1496=item *
1497
1498L<Version control conflict marker|perldiag/"Version control conflict marker">
1499
e6abae1c 1500(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
2c8edc25
S
1501C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
1502version control system to mark conflicts after a failed merge operation.
1503
1504=item *
1505
1506L<%s: command not found|perldiag/"%s: command not found">
1507
1508(A) You've accidentally run your script through B<bash> or another shell
1509instead of Perl. Check the #! line, or manually feed your script into
1510Perl yourself. The #! line at the top of your file could look like:
1511
1512 #!/usr/bin/perl
1513
1514=item *
1515
1516L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1517
1518(A) You've accidentally run your script through B<zsh> or another shell
1519instead of Perl. Check the #! line, or manually feed your script into
1520Perl yourself. The #! line at the top of your file could look like:
1521
1522 #!/usr/bin/perl
1523
1524=item *
1525
e6abae1c 1526L<Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<E<lt>-- HERE> in mE<sol>%sE<sol>|perldiag/"Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<<-- HERE> in m/%s/">
2c8edc25
S
1527
1528Unescaped left braces are already illegal in some contexts in regular
1529expression patterns, but, due to an oversight, no deprecation warning
1530was raised in other contexts where they are intended to become illegal.
1531This warning is now raised in these contexts.
1532
1533=item *
1534
1535L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1536
1537=item *
1538
1539L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1540
1541=item *
1542
1543L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1544
1545=item *
1546
1547L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1548
1549=back
1550
1551=head3 New Warnings
1552
1553=over 4
1554
1555=item *
1556
4f73c567 1557L<Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30|perldiag/"Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30">
2c8edc25
S
1558
1559See L</Deprecations>
1560
1561=item *
1562
1563L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1564
1565(S experimental::declared_refs) This warning is emitted if you use a reference
1566constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1567C<local()>. Simply suppress the warning if you want to use the feature, but
1568know that in doing so you are taking the risk of using an experimental feature
1569which may change or be removed in a future Perl version:
1570
1571 no warnings "experimental::declared_refs";
1572 use feature "declared_refs";
1573 $fooref = my \$foo;
1574
1575=item *
1576
4f73c567 1577L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25
S
1578
1579(D deprecated) The special variable C<${^ENCODING}>, formerly used to implement
1580the C<encoding> pragma, is no longer supported as of Perl 5.26.0.
1581
89853d76
DH
1582=item *
1583
1584Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1585a warning recommending to fix the C<do> statement:
1586
1587L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no
1588longer in @INC; did you mean do ".\/%s"?>
1589
2c8edc25
S
1590=back
1591
1592=head2 Changes to Existing Diagnostics
1593
1594=over 4
1595
1596=item *
1597
1598When a C<require> fails, we now do not provide C<@INC> when the C<require>
1599is for a file instead of a module.
1600
1601=item *
1602
1603When C<@INC> is not scanned for a C<require> call, we no longer display
1604C<@INC> to avoid confusion.
1605
1606=item *
1607
1608Attribute "locked" is deprecated, and will disappear in Perl 5.28
1609
1610=item *
1611
1612Attribute "unique" is deprecated, and will disappear in Perl 5.28
1613
1614=item *
1615
1616Constants from lexical variables potentially modified elsewhere are
1617deprecated. This will not be allowed in Perl 5.32
1618
1619=item *
1620
1621Deprecated use of my() in false conditional. This will be a fatal error
1622in Perl 5.30
1623
1624=item *
1625
1626dump() better written as CORE::dump(). dump() will no longer be available
1627in Perl 5.30
1628
1629=item *
1630
1631${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
1632
1633=item *
1634
1635File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
1636instead.
1637
1638=item *
1639
1640%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
1641
1642=item *
1643
1644$* is no longer supported. Its use will be fatal in Perl 5.30
1645
1646=item *
1647
1648$* is no longer supported. Its use will be fatal in Perl 5.30
1649
1650=item *
1651
1652Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1653
1654=item *
1655
1656Opening filehandle %s also as a directory. This will be a fatal
1657error in Perl 5.28
1658
1659=item *
1660
1661Setting $/ to a reference to %s as a form of slurp is deprecated,
1662treating as undef. This will be fatal in Perl 5.28
1663
1664=item *
1665
1666Unescaped left brace in regex is deprecated here (and will be fatal
1667in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
1668
1669=item *
1670
1671Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1672
1673=item *
1674
1675Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1676
1677=item *
1678
1679Use of code point 0x%s is deprecated; the permissible max is 0x%s.
1680This will be fatal in Perl 5.28
1681
1682=item *
1683
1684Use of comma-less variable list is deprecated. Its use will be fatal
1685in Perl 5.28
1686
1687=item *
1688
1689Use of inherited AUTOLOAD for non-method %s() is deprecated. This
1690will be fatal in Perl 5.28
1691
1692=item *
1693
1694Use of strings with code points over 0xFF as arguments to %s operator
1695is deprecated. This will be a fatal error in Perl 5.28
1696
1697=item *
1698
1699Improve error for missing tie() package/method. This brings the error messages
1700in line with the ones used for normal method calls, despite not using
1701call_method().
1702
1703=item *
1704
1705Make the sysread()/syswrite/() etc :utf8 handle warnings default. These
1706warnings were under 'deprecated' previously.
1707
1708=item *
1709
1710'do' errors now refer to 'do' (not 'require').
1711
1712=item *
1713
1714Details as to the exact problem have been added to the diagnostics that
1715occur when malformed UTF-8 is encountered when trying to convert to a
1716code point.
1717
1718=item *
1719
1720Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
1721blames the variable for an uninitialized-value warning encountered by the
1722tied/magical code.
1723
1724=item *
1725
e6abae1c 1726L<Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in mE<sol>%sE<sol>|perldiag/"Unescaped left brace in regex is illegal here in regex; marked by S<<-- HERE> in m/%s/">
2c8edc25
S
1727
1728The word "here" has been added to the message that was raised in
1729v5.25.1. This is to indicate that there are contexts in which unescaped
1730left braces are not (yet) illegal.
1731
1732=item *
1733
1734Code like C<$x = $x . "a"> was incorrectly failing to yield a
1735L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
1736warning when C<$x> was a lexical variable with an undefined value. That has
1737now been fixed. [perl #127877]
1738
1739=item *
1740
1741When the error "Experimental push on scalar is now forbidden" is raised for
1742the hash functions C<keys>, C<each>, and C<values>, it is now followed by
1743the more helpful message, "Type of arg 1 to whatever must be hash or
1744array". [perl #127976]
1745
1746=item *
1747
1748C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
1749argument to C<shift> or C<pop>, began crashing in Perl 5.14.0, but has now
1750been fixed.
1751
1752=item *
1753
1754C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
1755string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
1756bringing it into consistency with C<$$scalar>.
1757
1758=item *
1759
1760C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
1761do, but merely produce a syntax error. [perl #128171]
1762
1763=item *
1764
1765C<do> or C<require> with a reference or typeglob which, when stringified,
1766contains a null character started crashing in Perl 5.20.0, but has now been
1767fixed. [perl #128182]
1768
1769=back
1770
1771=head1 Utility Changes
1772
1773=head2 F<c2ph> and F<pstruct>
1774
1775=over 4
1776
1777=item *
1778
1779These old utilities have long since superceded by L<h2xs>, and are
1780now gone from the distribution.
1781
1782=back
1783
1784=head2 F<Porting/pod_lib.pl>
1785
1786=over 4
1787
1788=item *
1789
1790Removed spurious executable bit.
1791
1792=item *
1793
1794Account for possibility of DOS file endings.
1795
1796=back
1797
1798=head2 F<Porting/sync-with-cpan>
1799
1800=over 4
1801
1802=item *
1803
1804Many improvements
1805
1806=back
1807
1808=head2 F<perf/benchmarks>
1809
1810=over 4
1811
1812=item *
1813
1814Tidy file, rename some symbols.
1815
1816=back
1817
1818=head2 F<Porting/checkAUTHORS.pl>
1819
1820=over 4
1821
1822=item *
1823
1824Replace obscure character range with \w.
1825
1826=back
1827
1828=head2 F<t/porting/regen.t>
1829
1830=over 4
1831
1832=item *
1833
1834try to be more helpful when tests fail.
1835
1836=back
1837
1838=head2 F<utils/h2xs.PL>
1839
1840=over 4
1841
1842=item *
1843
1844Avoid infinite loop for enums.
1845
1846=back
1847
1848=head2 L<perlbug>
1849
1850=over 4
1851
1852=item *
1853
1854Long lines in the message body are now wrapped at 900 characters, to stay
1855well within the 1000-character limit imposed by SMTP mail transfer agents.
1856This is particularly likely to be important for the list of arguments to
1857C<Configure>, which can readily exceed the limit if, for example, it names
1858several non-default installation paths. This change also adds the first unit
1859tests for perlbug. [perl #128020]
1860
1861=back
1862
1863=head1 Configuration and Compilation
1864
1865=over 4
1866
1867=item *
1868
89853d76 1869C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1870
1871=item *
1872
1873The C<dtrace> build process has further changes:
1874
1875=over
1876
1877=item *
1878
1879If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1880built within a FreeBSD jail.
1881
1882=item *
1883
1884On systems that build a dtrace object file (FreeBSD, Solaris and
1885SystemTap's dtrace emulation), copy the input objects to a separate
1886directory and process them there, and use those objects in the link,
1887since C<dtrace -G> also modifies these objects.
1888
1889=item *
1890
1891Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1892to libelf symbols.
1893
1894=item *
1895
1896Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1897default build on Solaris generates probes from the unused inline
1898functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1899fail.
1900
1901=back
1902
1903[perl #130108]
1904
1905=item *
1906
1907You can now disable perl's use of the PERL_HASH_SEED and
1908PERL_PERTURB_KEYS environment variables by configuring perl with
1909C<-Accflags=NO_PERL_HASH_ENV>.
1910
1911=item *
1912
1913You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment
1914variable by configuring perl with
1915C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1916
1917=item *
1918
1919Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1920and C<Inf> to make builds more reproducible. [perl #130133]
1921
1922=item *
1923
1924Since 5.18 for testing purposes we have included support for
1925building perl with a variety of non-standard, and non-recommended
1926hash functions. Since we do not recommend the use of these functions
1927we have removed them and their corresponding build options. Specifically
1928this includes the following build options:
1929
1930 PERL_HASH_FUNC_SDBM
1931 PERL_HASH_FUNC_DJB2
1932 PERL_HASH_FUNC_SUPERFAST
1933 PERL_HASH_FUNC_MURMUR3
1934 PERL_HASH_FUNC_ONE_AT_A_TIME
1935 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1936 PERL_HASH_FUNC_MURMUR_HASH_64A
1937 PERL_HASH_FUNC_MURMUR_HASH_64B
1938
1939=item *
1940
1941Remove "Warning: perl appears in your path"
1942
1943This install warning is more or less obsolete, since most platforms already
1944*will* have a /usr/bin/perl or similar provided by the OS.
1945
1946=item *
1947
1948Reduce verbosity of "make install.man"
1949
1950Previously, two progress messages were emitted for each manpage: one by
1951installman itself, and one by the function in install_lib.pl that it calls to
1952actually install the file. Disabling the second of those in each case saves
1953over 750 lines of unhelpful output.
1954
1955=item *
1956
1957Cleanup for clang -Weverything support. [perl 129961]
1958
1959=item *
1960
1961Configure: signbit scan was assuming too much, stop assuming negative 0.
1962
1963=item *
1964
1965Various compiler warnings have been silenced.
1966
1967=item *
1968
1969Several smaller changes have been made to remove impediments to compiling under
1970C++11.
1971
1972=item *
1973
1974Builds using C<USE_PAD_RESET> now work again; this configuration had
1975bit-rotted.
1976
1977=item *
1978
1979A probe for C<gai_strerror> was added to F<Configure> that checks if the
1980the gai_strerror() routine is available and can be used to
1981translate error codes returned by getaddrinfo() into human
1982readable strings.
1983
1984=item *
1985
1986F<Configure> now aborts if both "-Duselongdouble" and "-Dusequadmath" are
1987requested.
1988L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1989
1990=item *
1991
1992Fixed a bug in which F<Configure> could append "-quadmath" to the archname even
1993if it was already present.
1994L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1995
1996=item *
1997
1998Clang builds with "-DPERL_GLOBAL_STRUCT" or "-DPERL_GLOBAL_STRUCT_PRIVATE" have
1999been fixed (by disabling Thread Safety Analysis for these configurations).
2000
2001=item *
2002
2003F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
2004files require updates. This could cause dependencies, F<perlmain.c>
2005in particular, to be rebuilt unnecessarily. [perl #126710]
2006
2007=item *
2008
2009The output of C<perl -V> has been reformatted so that each configuration
2010and compile-time option is now listed one per line, to improve
2011readability.
2012
2013=item *
2014
2015C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
2016invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
2017This means you can supply your target platform C<config.sh>, generate
2018the headers and proceed to build your cross-target perl. [perl #127234]
2019
2020=item *
2021
2022Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
2023counts when the environment variable C<PERL_TRACE_OPS> to be set to a
2024non-zero integer. This allows C<make test> to pass on such a build.
2025
2026=item *
2027
2028When building with GCC 6 and link-time optimization (the C<-flto> option to
2029C<gcc>), C<Configure> was treating all probed symbols as present on the
2030system, regardless of whether they actually exist. This has been fixed.
2031[perl #128131]
2032
2033=item *
2034
2035The F<t/test.pl> library is used for internal testing of Perl itself, and
2036also copied by several CPAN modules. Some of those modules must work on
2037older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
2038features. Compatibility with Perl 5.8 was inadvertently removed some time
2039ago; it has now been restored. [perl #128052]
2040
2041=item *
2042
2043The build process no longer emits an extra blank line before building each
2044"simple" extension (those with only F<*.pm> and F<*.pod> files).
2045
2046=back
2047
2048=head1 Testing
2049
2050=over 4
2051
2052=item *
2053
2054F<XS-APItest/t/utf8.t>: Several small fixes and enhancements.
2055
2056=item *
2057
2058Tests for locales were erroneously using locales incompatible with Perl.
2059
2060=item *
2061
2062Some parts of the test suite that try to exhaustively test edge cases in the
2063regex implementation have been restricted to running for a maximum of five
2064minutes. On slow systems they could otherwise take several hours, without
2065significantly improving our understanding of the correctness of the code
2066under test.
2067
2068In addition, some of those test cases have been split into more files, to
2069allow them to be run in parallel on suitable systems.
2070
2071=item *
2072
2073A new internal facility allows analysing the time taken by the individual
2074tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
2075
2076=item *
2077
2078F<t/re/regexp_nonull.t> has been added to test that the regular expression
2079engine can handle scalars that do not have a null byte just past the end of
2080the string.
2081
2082=item *
2083
2084A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
2085"Declaring a reference to a variable".
2086
2087=item *
2088
2089A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
2090generated by bracketed character classes are as expected.
2091
2092=item *
2093
2094F<t/harness> now tries really hard not to run tests outside of the Perl
2095source tree. [perl #124050]
2096
2097=back
2098
2099=head1 Platform Support
2100
2101=head2 New Platforms
2102
2103=over 4
2104
2105=item NetBSD/VAX
2106
2107Perl now compiles under NetBSD on VAX machines. However, it's not
2108possible for that platform to implement floating-point infinities and
2109NaNs compatibly with most modern systems, which implement the IEEE-754
2110floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2111literals, C<printf %a>) is not implemented, either.
2112The C<make test> passes 98% of tests.
2113
2114=over 4
2115
2116=item *
2117
2118Test fixes and minor updates.
2119
2120=item *
2121
2122Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2123
2124=back
2125
2126=back
2127
2128=head2 Platform-Specific Notes
2129
2130=over 4
2131
2132=item Darwin
2133
2134don't treat -Dprefix=/usr as special, instead require an extra option
2135-Ddarwin_distribution to produce the same results.
2136
2137=item POSIX
2138
2139Finish removing POSIX deprecated functions.
2140
2141=item OS X
2142
2143OS X El Capitan doesn't implement the clock_gettime() or clock_getres() APIs,
2144emulate them as necessary.
2145
2146=item macOS
2147
2148Deprecated syscall(2) on macOS 10.12.
2149
2150=item EBCDIC
2151
2152Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2153
2154=item HP-UX
2155
2156L<Net::Ping> UDP test is skipped on HP-UX.
2157
2158=item Hurd
2159
2160The hints for Hurd have been improved enabling malloc wrap and reporting the
2161GNU libc used (previously it was an empty string when reported).
2162
2163=item VAX
2164
2165VAX floating point formats are now supported.
2166
2167=item VMS
2168
2169=over 4
2170
2171=item *
2172
2173The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
2174now a colon (C<:>) when running under a Unix shell. There is no change when
2175running under DCL (it's still C<|>).
2176
2177=item *
2178
2179Remove some VMS-specific hacks from C<showlex.t>. These were added 15 years
2180ago, and are no longer necessary for any VMS version now supported.
2181
2182=item *
2183
2184Move C<_pDEPTH> and C<_aDEPTH> after F<config.h> otherwise DEBUGGING
2185may not be defined yet.
2186
2187=item *
2188
2189VAXC has not been a possibility for a good long while, and the versions of the
2190DEC/Compaq/HP/VSI C compiler that report themselves as "DEC" in a listing file
2191are 15 years or more out-of-date and can be safely desupported.
2192
2193=back
2194
2195=item Windows
2196
2197=over 4
2198
2199=item *
2200
2201Support for compiling perl on Windows using Microsoft Visual Studio 2015
2202(containing Visual C++ 14.0) has been added.
2203
2204This version of VC++ includes a completely rewritten C run-time library, some
2205of the changes in which mean that work done to resolve a socket close() bug in
2206perl #120091 and perl #118059 is not workable in its current state with this
2207version of VC++. Therefore, we have effectively reverted that bug fix for
2208VS2015 onwards on the basis that being able to build with VS2015 onwards is
2209more important than keeping the bug fix. We may revisit this in the future to
2210attempt to fix the bug again in a way that is compatible with VS2015.
2211
2212These changes do not affect compilation with GCC or with Visual Studio versions
2213up to and including VS2013, i.e. the bug fix is retained (unchanged) for those
2214compilers.
2215
2216Note that you may experience compatibility problems if you mix a perl built
2217with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2218perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2219Some incompatibility may arise because of the bug fix that has been reverted
2220for VS2015 builds of perl, but there may well be incompatibility anyway because
2221of the rewritten CRT in VS2015 (e.g. see discussion at
2222http://stackoverflow.com/questions/30412951).
2223
2224=back
2225
2226=item Win32
2227
2228=over 4
2229
2230=item *
2231
2232Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2233depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
2234the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2235
2236=item *
2237
2238fp definitions have been updated.
2239
2240=back
2241
2242=item VMS And Win32
2243
2244Fix some breakage, add 'undef' value for default_inc_excludes_dot in build
2245scripts.
2246
2247=item Linux
2248
2249Drop support for Linux a.out Linux has used ELF for over twenty years.
2250
2251=item OpenBSD 6
2252
2253OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2254Make sure this is accounted for.
2255
2256=item FreeBSD
2257
2258t/uni/overload.t: Skip hanging test on FreeBSD.
2259
2260=back
2261
2262=head1 Internal Changes
2263
2264=over 4
2265
2266=item *
2267
2268The C<op_class()> API function has been added. This is like the existing
2269C<OP_CLASS()> macro, but can more accurately determine what struct an op
2270has been allocated as. For example C<OP_CLASS()> might return
2271C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2272allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2273C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2274
2275=item *
2276
2277The output format of the C<op_dump()> function (as used by C<perl -Dx>)
2278has changed: it now displays an "ASCII-art" tree structure, and shows more
2279low-level details about each op, such as its address and class.
2280
2281=item *
2282
2283New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
2284been added, each with the
2285suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
2286parameter, giving an upper limit of how far into the string it is safe
2287to read. Using the old versions could cause attempts to read beyond the
2288end of the input buffer if the UTF-8 is not well-formed, and their use
2289now raises a deprecation warning. Details are at
2290L<perlapi/Character classification>.
2291
2292=item *
2293
2294Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
2295deprecation warning since Perl v5.18. They now die.
2296Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
2297
2298=item *
2299
2300Calling the functions C<utf8n_to_uvchr> and its derivatives, while
2301passing a string length of 0 is now asserted against in DEBUGGING
2302builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If
2303you have nothing to decode, you shouldn't call the decode function.
2304
2305=item *
2306
2307The functions C<utf8n_to_uvchr> and its derivatives now return the
2308Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong
2309malformation, and that malformation is allowed by the input parameters.
2310This malformation is where the UTF-8 looks valid syntactically, but
2311there is a shorter sequence that yields the same code point. This has
2312been forbidden since Unicode version 3.1.
2313
2314=item *
2315
2316The functions C<utf8n_to_uvchr> and its derivatives now accept an input
2317flag to allow the overflow malformation. This malformation is when the
2318UTF-8 may be syntactically valid, but the code point it represents is
2319not capable of being represented in the word length on the platform.
2320What "allowed" means in this case is that the function doesn't return an
2321error, and advances the parse pointer to beyond the UTF-8 in question,
2322but it returns the Unicode REPLACEMENT CHARACTER as the value of the
2323code point (since the real value is not representable).
2324
2325=item *
2326
2327The C<PADOFFSET> type has changed from being unsigned to signed, and
2328several pad-related variables such as C<PL_padix> have changed from being
2329of type C<I32> to type C<PADOFFSET>.
2330
2331=item *
2332
2333The function C<L<perlapi/utf8n_to_uvchr>> has been changed to not
2334abandon searching for other malformations when the first one is
2335encountered. A call to it thus can generate multiple diagnostics,
2336instead of just one.
2337
2338=item *
2339
2340A new function, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
2341use by modules that need to know the details of UTF-8 malformations
2342beyond pass/fail. Previously, the only ways to know why a sequence was
2343ill-formed was to capture and parse the generated diagnostics, or to do
2344your own analysis.
2345
2346=item *
2347
2348Several new functions for handling Unicode have been added to the API:
2349C<L<perlapi/is_strict_utf8_string>>,
2350C<L<perlapi/is_c9strict_utf8_string>>,
2351C<L<perlapi/is_utf8_string_flags>>,
2352C<L<perlapi/is_strict_utf8_string_loc>>,
2353C<L<perlapi/is_strict_utf8_string_loclen>>,
2354C<L<perlapi/is_c9strict_utf8_string_loc>>,
2355C<L<perlapi/is_c9strict_utf8_string_loclen>>,
2356C<L<perlapi/is_utf8_string_loc_flags>>,
2357C<L<perlapi/is_utf8_string_loclen_flags>>,
2358C<L<perlapi/is_utf8_fixed_width_buf_flags>>,
2359C<L<perlapi/is_utf8_fixed_width_buf_loc_flags>>,
2360C<L<perlapi/is_utf8_fixed_width_buf_loclen_flags>>.
2361
2362These functions are all extensions of the C<is_utf8_string_*()> functions,
2363that apply various restrictions to the UTF-8 recognized as valid.
2364
2365=item *
2366
2367A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
2368length and allocated size of the buffer in an C<SV>, growing the buffer if
2369necessary.
2370
2371=item *
2372
2373A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
2374like Perl-space C<$x = ''>, but with several optimisations.
2375
2376=item *
2377
2378All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2379previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2380that several parts of the internals had to be special-cased to accommodate
2381it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2382that is now handled in a simpler way.
2383
2384=item *
2385
2386Several new internal C macros have been added that take a string literal as
2387arguments, alongside existing routines that take the equivalent value as two
2388arguments, a character pointer and a length. The advantage of this is that
2389the length of the string is calculated automatically, rather than having to
2390be done manually. These routines are now used where appropriate across the
2391entire codebase.
2392
2393=item *
2394
2395The code in F<gv.c> that determines whether a variable has a special meaning
2396to Perl has been simplified.
2397
2398=item *
2399
2400The C<DEBUGGING>-mode output for regex compilation and execution has been
2401enhanced.
2402
2403=item *
2404
2405Several macros and functions have been added to the public API for
2406dealing with Unicode and UTF-8-encoded strings. See
2407L<perlapi/Unicode Support>.
2408
2409=item *
2410
2411Use C<my_strlcat()> in C<locale.c>. While C<strcat()> is safe in this context,
2412some compilers were optimizing this to C<strcpy()> causing a porting test to
2413fail that looks for unsafe code. Rather than fighting this, we just use
2414C<my_strlcat()> instead.
2415
2416=item *
2417
2418Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
2419been added. These are intended principally to implement the individual
2420elements of a subroutine signature, plus any overall checking required.
2421
2422=item *
2423
2424Perl no longer panics when switching into some locales on machines with
2425buggy C<strxfrm()> implementations in their libc. [perl #121734]
2426
2427=item *
2428
2429Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
2430default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2431This flag alters how the C<op_sibling> field is used in C<OP> structures,
2432and has been available optionally since perl 5.22.0.
2433
2434See L<perl5220delta/"Internal Changes"> for more details of what this
2435build option does.
2436
2437=item *
2438
2439The meanings of some internal SV flags have been changed
2440
2441OPpRUNTIME, SVpbm_VALID, SVpbm_TAIL, SvTAIL_on, SvTAIL_off, SVrepl_EVAL,
2442SvEVALED
2443
2444=item *
2445
2446Change C<hv_fetch(…, "…", …, …)> to C<hv_fetchs(…, "…", …)>
2447
2448The dual-life dists all use Devel::PPPort, so they can use this function even
2449though it was only added in 5.10.
2450
2451=back
2452
2453=head1 Selected Bug Fixes
2454
2455=over 4
2456
2457=item *
2458
2459C< $-{$name} > would leak an C<AV> on each access if the regular
2460expression had no named captures. The same applies to access to any
2461hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2462#130822]
2463
2464=item *
2465
2466Attempting to use the deprecated variable C<$#> as the object in an
2467indirect object method call could cause a heap use after free or
2468buffer overflow. [perl #129274]
2469
2470=item *
2471
2472When checking for an indirect object method call in some rare cases
2473the parser could reallocate the line buffer but then continue to use
2474pointers to the old buffer. [perl #129190]
2475
2476=item *
2477
2478Supplying a glob as the format argument to L<perlfunc/formline> would
2479cause an assertion failure. [perl #130722]
2480
2481=item *
2482
2483Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
2484converted into a qr// operator, leaving extra elements on the stack to
2485confuse any surrounding expression. [perl #130705]
2486
2487=item *
2488
2489Since 5.24.0 in some obscure cases, a regex which included code blocks
2490from multiple sources (e.g. via embedded via qr// objects) could end up
2491with the wrong current pad and crash or give weird results. [perl #129881]
2492
2493=item *
2494
2495Occasionally C<local()>s in a code block within a patterns weren't being
2496undone when the pattern matching backtracked over the code block.
2497[perl #126697]
2498
2499=item *
2500
2501Using C<substr()> to modify a magic variable could access freed memory
2502in some cases. [perl #129340]
2503
2504=item *
2505
2506Perl 5.25.9 was fixed so that under C<use utf8>, the entire Perl program
2507is checked that the UTF-8 is wellformed. It turns out that several edge
2508cases were missed, and are now fixed. [perl #126310] was the original
2509ticket.
2510
2511=item *
2512
2513Under C<use utf8>, the entire Perl program is now checked that the UTF-8
2514is wellformed. This resolves [perl #126310].
2515
2516=item *
2517
2518The range operator C<..> on strings now handles its arguments correctly when in
2519the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
2520feature. The previous behaviour was sufficiently unexpected that we believe no
2521correct program could have made use of it.
2522
2523=item *
2524
2525The S<split> operator did not ensure enough space was allocated for
2526its return value in scalar context. It could then write a single
2527pointer immediately beyond the end of the memory block allocated for
2528the stack. [perl #130262]
2529
2530=item *
2531
2532Using a large code point with the C<W> pack template character with
2533the current output position aligned at just the right point could
2534cause a write a single zero byte immediately beyond the end of an
2535allocated buffer. [perl #129149]
2536
2537=item *
2538
2539Supplying the form picture argument as part of the form argument list
2540where the picture specifies modifying the argument could cause an
2541access to the new freed compiled form. [perl #129125]
2542
2543=item *
2544
2545Fix a problem with sort's build-in compare, where it would not sort
2546correctly with 64-bit integers, and non-long doubles. [perl #130335]
2547
2548=item *
2549
2550Fix issues with /(?{ ... E<lt>E<lt>EOF })/ that broke Method-Signatures. [perl #130398]
2551
2552=item *
2553
2554Fix a macro which caused syntax error on an EBCDIC build.
2555
2556=item *
2557
2558Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2559
2560=item *
2561
2562Fixed an assertion failure with C<chop> and C<chomp>, which
2563could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2564
2565=item *
2566
2567Fixed a comment skipping error under C</x>; it could stop skipping a
2568byte early, which could be in the middle of a UTF-8 character.
2569[perl #130495].
2570
2571=item *
2572
2573F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2574
2575=item *
2576
2577Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2578
2579=item *
2580
2581DragonFly BSD now has support for setproctitle(). [perl #130068].
2582
2583=item *
2584
2585Fix an assertion error which could be triggered when lookahead string
2586in patterns exceeded a minimum length. [perl #130522].
2587
2588=item *
2589
2590Only warn once per literal about a misplaced C<_>. [perl #70878].
2591
2592=item *
2593
2594Ensure range-start is set after error in C<tr///>. [perl #129342].
2595
2596=item *
2597
2598Don't read past start of string for unmatched backref; otherwise,
2599we may have heap buffer overflow. [perl #129377].
2600
2601=item *
2602
2603Properly recognize mathematical digit ranges starting at U+1D7E.
2604C<use re 'strict'> is supposed to warn if you use a range whose start
2605and end digit aren't from the same group of 10. It didn't do that
2606for five groups of mathematical digits starting at U+1D7E.
2607
2608=item *
2609
2610A sub containing a "forward" declaration with the same name (e.g.,
2611C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2612#129090]
2613
2614=item *
2615
2616A crash in executing a regex with a floating UTF-8 substring against a
2617target string that also used UTF-8 has been fixed. [perl #129350]
2618
2619=item *
2620
2621Previously, a shebang line like C<#!perl -i u> could be erroneously
2622interpreted as requesting the C<-u> option. This has been fixed. [perl
2623#129336]
2624
2625=item *
2626
2627The regex engine was previously producing incorrect results in some rare
2628situations when backtracking past a trie that matches only one thing; this
2629showed up as capture buffers (C<$1>, C<$2>, etc) erroneously containing data
2630from regex execution paths that weren't actually executed for the final
2631match. [perl #129897]
2632
2633=item *
2634
2635Certain regexes making use of the experimental C<regex_sets> feature could
2636trigger an assertion failure. This has been fixed. [perl #129322]
2637
2638=item *
2639
2640Invalid assignments to a reference constructor (e.g., C<\eval=time>) could
2641sometimes crash in addition to giving a syntax error. [perl #125679]
2642
2643=item *
2644
2645The parser could sometimes crash if a bareword came after C<evalbytes>.
2646[perl #129196]
2647
2648=item *
2649
2650Autoloading via a method call would warn erroneously ("Use of inherited
2651AUTOLOAD for non-method") if there was a stub present in the package into
2652which the invocant had been blessed. The warning is no longer emitted in
2653such circumstances. [perl #47047]
2654
2655=item *
2656
2657A sub containing with a "forward" declaration with the same name (e.g.,
2658C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2659#129090]
2660
2661=item *
2662
2663The use of C<splice> on arrays with nonexistent elements could cause other
2664operators to crash. [perl #129164]
2665
2666=item *
2667
2668Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2669string. [perl #129012]
2670
2671=item *
2672
2673Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2674checking that the I<current> C<cx> is the right type, and instead was always
2675checking the base C<cx> (effectively a noop). [perl #129029]
2676
2677=item *
2678
2679Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2680maintains up to two pointers into the parser buffer, one of which can
2681become stale under the right conditions. [perl #129069]
2682
2683=item *
2684
2685Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2686when it wasn't. [perl #129038]
2687
2688=item *
2689
2690Fixed place where regex was not setting the syntax error correctly.
2691[perl #129122]
2692
2693=item *
2694
2695The C<&.> operator (and the C<&> operator, when it treats its arguments as
2696strings) were failing to append a trailing null byte if at least one string
2697was marked as utf8 internally. Many code paths (system calls, regexp
2698compilation) still expect there to be a null byte in the string buffer
2699just past the end of the logical string. An assertion failure was the
2700result. [perl #129287]
2701
2702=item *
2703
2704Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2705silently truncates the supplied path if it won't fit into the C<sun_path>
2706member of C<sockaddr_un>. This may change in the future, but for now
2707check the path in theC<sockaddr> matches the desired path, and skip if
2708it doesn't. [perl #128095]
2709
2710=item *
2711
2712Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2713cases this is used in building error messages. [perl #128988]
2714
2715=item *
2716
2717Check for null PL_curcop in IN_LC() [perl #129106]
2718
2719=item *
2720
2721Fixed the parser error handling for an 'C<:attr(foo>' that does not have
2722an ending 'C<)>'.
2723
2724=item *
2725
2726Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2727actually fixed two bugs, [perl #129064] and [perl #129176].
2728
2729=item *
2730
2731[perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to
2732prevent possible string overrun with invalid len in gv.c
2733
2734=item *
2735
2736Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2737where the source and destination of the sort are the same plain array, are
2738optimised to do less copying around. Two side-effects of this optimisation
2739were that the contents of C<@a> as visible to to sort routine were
2740partially sorted, and under some circumstances accessing C<@a> during the
2741sort could crash the interpreter. Both these issues have been fixed, and
2742Sort functions see the original value of C<@a>.
2743
2744=item *
2745
2746Non-ASCII string delimiters are now reported correctly in error messages
2747for unterminated strings. [perl #128701]
2748
2749=item *
2750
2751C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2752temporary value") erroneously in some cases, but has been fixed.
2753
2754=item *
2755
2756C<@DB::args> is now exempt from "used once" warnings. The warnings only
2757occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2758multiple times.
2759
2760=item *
2761
2762The use of built-in arrays or hash slices in a double-quoted string no
2763longer issues a warning ("Possible unintended interpolation...") if the
2764variable has not been mentioned before. This affected code like
2765C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2766C<@-> and C<@+> were already exempt from the warning.)
2767
2768=item *
2769
2770C<gethostent> and similar functions now perform a null check internally, to
2771avoid crashing with torsocks. This was a regression from 5.22. [perl
2772#128740]
2773
2774=item *
2775
2776C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2777memory if the typeglob in question has never been accessed before.
2778
2779=item *
2780
2781In 5.25.4 fchown() was changed not to accept negative one as an argument
2782because in some platforms that is an error. However, in some other platforms
2783that is an acceptable argument. This change has been reverted [perl #128967].
2784
2785=item *
2786
2787Mentioning the same constant twice in a row (which is a syntax error) no
2788longer fails an assertion under debugging builds. This was a regression
2789from 5.20. [perl #126482]
2790
2791=item *
2792
2793Many issues relating to C<printf "%a"> of hexadecimal floating point
2794were fixed. In addition, the "subnormals" (formerly known as "denormals")
2795floating point anumbers are now supported both with the plain IEEE 754
2796floating point numbers (64-bit or 128-bit) and the x86 80-bit
2797"extended precision". Note that subnormal hexadecimal floating
2798point literals will give a warning about "exponent underflow".
2799[perl #128843, #128889, #128890, #128893, #128909, #128919]
2800
2801=item *
2802
2803A regression in 5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2804128 and 255 has been fixed. [perl #128734].
2805
2806=item *
2807
2808A regression from the previous development release, 5.23.3, where
2809compiling a regular expression could crash the interpreter has been
2810fixed. [perl #128686].
2811
2812=item *
2813
2814Use of a string delimiter whose code point is above 2**31 now works
2815correctly on platforms that allow this. Previously, certain characters,
2816due to truncation, would be confused with other delimiter characters
2817with special meaning (such as C<?> in C<m?...?>), resulting
2818in inconsistent behaviour. Note that this is non-portable,
2819and is based on Perl's extension to UTF-8, and is probably not
2820displayable nor enterable by any editor. [perl #128738]
2821
2822=item *
2823
2824C<@{x> followed by a newline where C<x> represents a control or non-ASCII
2825character no longer produces a garbled syntax error message or a crash.
2826[perl #128951]
2827
2828=item *
2829
2830An assertion failure with C<%: = 0> has been fixed.
2831L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2832
2833=item *
2834
2835In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2836that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2837was to parse it as C<$foo:: . $bar>, has been restored.
2838L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2839
2840=item *
2841
2842Since Perl 5.20, line numbers have been off by one when perl is invoked with
2843the B<-x> switch. This has been fixed.
2844L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2845
2846=item *
2847
2848Vivifying a subroutine stub in a deleted stash (e.g., C<delete $My::{"Foo::"};
2849\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2850L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2851
2852=item *
2853
2854Some obscure cases of subroutines and file handles being freed at the same time
2855could result in crashes, but have been fixed. The crash was introduced in Perl
28565.22.
2857L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2858
2859=item *
2860
2861Code that looks for a variable name associated with an uninitialized value
2862could cause an assertion in cases where magic is involved, such as
2863C<$ISA[0][0]>. This has now been fixed.
2864L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2865
2866=item *
2867
2868A crash caused by code generating the warning "Subroutine STASH::NAME
2869redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2870fixed. In these cases, where the STASH is missing, the warning will now appear
2871as "Subroutine NAME redefined".
2872L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2873
2874=item *
2875
2876Fixed an assertion triggered by some code that handles deprecated behavior in
2877formats, e.g. in cases like this:
2878
2879 format STDOUT =
2880 @
2881 0"$x"
2882
2883L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2884
2885=item *
2886
2887A possible divide by zero in string transformation code on Windows has been
2888avoided, fixing a crash when collating an empty string.
2889L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2890
2891=item *
2892
2893Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2894regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2895L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2896
2897=item *
2898
2899C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2900warn when syntax warnings are enabled. [perl #127333]
2901
2902=item *
2903
2904socket() now leaves the error code returned by the system in C<$!> on
2905failure. [perl #128316]
2906
2907=item *
2908
2909Assignment variants of any bitwise ops under the C<bitwise> feature would
2910crash if the left-hand side was an array or hash. [perl #128204]
2911
2912=item *
2913
2914C<require> followed by a single colon (as in C<foo() ? require : ...> is
2915now parsed correctly as C<require> with implicit $_, rather than
2916C<require "">. [perl #128307]
2917
2918=item *
2919
2920Scalar C<keys %hash> can now be assigned to consistently in all scalar
2921lvalue contexts. Previously it worked for some contexts but not others.
2922
2923=item *
2924
2925List assignment to C<vec> or C<substr> with an array or hash for its first
2926argument used to result in crashes or "Can't coerce" error messages at run
2927time, unlike scalar assignment, which would give an error at compile time.
2928List assignment now gives a compile-time error, too. [perl #128260]
2929
2930=item *
2931
2932Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
2933and C<or>) were being compiled incorrectly in some cases. If the left-hand
2934side consisted of either a negated bareword constant or a negated C<do {}>
2935block containing a constant expression, and the right-hand side consisted of
2936a negated non-foldable expression, one of the negations was effectively
2937ignored. The same was true of C<if> and C<unless> statement modifiers,
2938though with the left-hand and right-hand sides swapped. This long-standing
2939bug has now been fixed. [perl #127952]
2940
2941=item *
2942
2943C<reset> with an argument no longer crashes when encountering stash entries
2944other than globs. [perl #128106]
2945
2946=item *
2947
2948Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2949longer causes crashes. [perl #128086]
2950
2951=item *
2952
2953Handle SvIMMORTALs in LHS of list assign. [perl #129991]
2954
2955=item *
2956
2957[perl #130010] a5540cf breaks texinfo
2958
2959This involved user-defined Unicode properties.
2960
2961=item *
2962
2963Fix error message for unclosed C<\N{> in regcomp.
2964
2965An unclosed C<\N{> could give the wrong error message
2966C<"\N{NAME} must be resolved by the lexer">.
2967
2968=item *
2969
2970List assignment in list context where the LHS contained aggregates and
2971where there were not enough RHS elements, used to skip scalar lvalues.
2972Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
2973it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2974returns C<($a,$b,$c)>. This can be seen in the following:
2975
2976 sub inc { $_++ for @_ }
2977 inc(($a,$b,@c,$d) = (10))
2978
2979Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2980now they are C<(11,1,1)>.
2981
2982=item *
2983
2984[perl 129903]
2985
2986The basic problem is that code like this: /(?{ s!!! })/ can trigger infinite
2987recursion on the C stack (not the normal perl stack) when the last successful
2988pattern in scope is itself. Since the C stack overflows this manifests as an
2989untrappable error/segfault, which then kills perl.
2990
2991We avoid the segfault by simply forbidding the use of the empty pattern when it
2992would resolve to the currently executing pattern.
2993
2994=item *
2995
2996[perl 128997] Avoid reading beyond the end of the line buffer when there's a
2997short UTF-8 character at the end.
2998
2999=item *
3000
3001[perl 129950] fix firstchar bitmap under utf8 with prefix optimisation.
3002
3003=item *
3004
3005[perl 129954] Carp/t/arg_string.t: be liberal in f/p formats.
3006
3007=item *
3008
3009[perl 129928] make do "a\0b" fail silently instead of throwing.
3010
3011=item *
3012
3013[perl 129130] make chdir allocate the stack it needs.
3014
3015=back
3016
3017=head1 Known Problems
3018
3019=over 4
3020
3021=item *
3022
3023Some modules have been broken by the L<context stack rework|/Internal Changes>.
3024These modules were relying on non-guaranteed implementation details in perl.
3025Their maintainers have been informed, and should contact perl5-porters for
3026advice if needed. Below is a subset of these modules:
3027
3028=over 4
3029
3030=item * L<Algorithm::Permute>
3031
3032=item * L<Coro>
3033
3034L<Coro> and perl v5.22.0 were already incompatible due to a change in the perl,
3035and the reworking on the perl context stack creates a further incompatibility.
3036perl5-porters has L<discussed the issue on the mailing
3037list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
3038
3039=item * L<Data::Alias>
3040
3041=item * L<RPerl>
3042
3043=item * L<Scope::Upper>
3044
3045=item * L<TryCatch>
3046
3047=back
3048
3049=item *
3050
3051The module L<lexical::underscore> no longer works on perl v5.24.0, because perl
3052no longer has a lexical C<$_>!
3053
3054=item *
3055
3056C<mod_perl> has been patched for compatibility for v5.22.0 and later but no
3057release has been made. The relevant patch (and other changes) can be found in
3058their source code repository, L<mirrored at
3059GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
3060
3061=back
3062
3063=head1 Errata From Previous Releases
3064
3065=over 4
3066
3067=item *
3068
3069Parsing bad POSIX charclasses no longer leaks memory. This was fixed in Perl
30705.25.2
3071L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
3072
3073=item *
3074
3075Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.0.
3076L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
3077
3078=back
3079
3080=head1 Obituary
3081
3082Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
3083member, has passed away on August 10, 2016. He will be remembered and
3084missed by all those with which he came in contact and enriched with his
3085intellect, wit, and spirit.
3086
3087It is with great sadness we also note Kip Hampton's passing.. Probably
3088best known as the author of the Perl & XML column on XML.com, he was a
3089core contributor to AxKit, an XML server platform that became an Apache
3090Foundation project. He was a frequent speaker in the early days at
3091OSCON, and most recently at YAPC::NA in Madison. He was frequently on
3092irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
3093group responsible for YAPC::NA Asheville in 2011.
a049258c 3094
2c8edc25
S
3095Kip and his constant contributions to the community will be greatly
3096missed.
a049258c
S
3097
3098=head1 Acknowledgements
2e0dcc12 3099
0cc8c746 3100Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 3101and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
S
3102authors.
3103
3104Excluding auto-generated files, documentation and release tools, there were
3105approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
3106
3107Perl continues to flourish into its third decade thanks to a vibrant community
3108of users and developers. The following people are known to have contributed the
3109improvements that became Perl 5.24.1:
3110
3111Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
3112König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
3113Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
3114Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
3115Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
3116Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3117Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3118Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3119D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3120Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3121De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3122Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3123Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3124Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3125Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3126Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3127Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3128Yves Orton, Zefram.
0cc8c746
S
3129
3130The list above is almost certainly incomplete as it is automatically generated
3131from version control history. In particular, it does not include the names of
3132the (very much appreciated) contributors who reported issues to the Perl bug
3133tracker.
3134
3135Many of the changes included in this version originated in the CPAN modules
3136included in Perl's core. We're grateful to the entire CPAN community for
3137helping Perl to flourish.
3138
3139For a more complete list of all of Perl's historical contributors, please see
3140the F<AUTHORS> file in the Perl source distribution.
f5b73711 3141
44691e6f
AB
3142=head1 Reporting Bugs
3143
2c8edc25
S
3144If you find what you think is a bug, you might check the articles recently
3145posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3146L<https://rt.perl.org/> . There may also be information at
4b8803f0 3147L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3148
e08634c5
SH
3149If you believe you have an unreported bug, please run the L<perlbug> program
3150included with your release. Be sure to trim your bug down to a tiny but
3151sufficient test case. Your bug report, along with the output of C<perl -V>,
3152will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
44691e6f 3153
87c118b9
DM
3154If the bug you are reporting has security implications which make it
3155inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3156L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3157for details of how to report the issue.
44691e6f
AB
3158
3159=head1 SEE ALSO
3160
e08634c5
SH
3161The F<Changes> file for an explanation of how to view exhaustive details on
3162what changed.
44691e6f
AB
3163
3164The F<INSTALL> file for how to build Perl.
3165
3166The F<README> file for general stuff.
3167
3168The F<Artistic> and F<Copying> files for copyright information.
3169
3170=cut