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perldelta: Add a section for undeprecations
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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
16beba24 14This release includes three updates with widespread effects:
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15
16=over 4
17
18=item * C<.> no longer in C<@INC>
19
95b17558 20The current modules, and for the execution of scripts. See the section
07b4a50c 21L<< Removal of the current directory (C<.>) from C<@INC> >> for the full details.
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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
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28=item * In regular expression patterns, a literal left brace C<"{">
29should be escaped
30
31See L</Unescaped literal C<"{"> characters in regular expression patterns are no longer permissible>.
32
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33=back
34
2c8edc25 35=head1 Core Enhancements
f3ed8cbf 36
2c8edc25 37=head2 New regular expression modifier C</xx>
f4b40f11 38
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39Specifying two C<x> characters to modify a regular expression pattern
40does everything that a single one does, but additionally TAB and SPACE
41characters within a bracketed character class are generally ignored and
42can be added to improve readability, like
43S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
44L<perlre/E<sol>x and E<sol>xx>.
5e50eae4 45
2c8edc25 46=head2 New Hash Function For 64-bit Builds
a049258c 47
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48We have switched to a hybrid hash function to better balance
49performance for short and long keys.
50
51For short keys, 16 bytes and under, we use an optimised variant of
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52One At A Time Hard, and for longer keys we use Siphash 1-3. For very
53long keys this is a big improvement in performance. For shorter keys
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54there is a modest improvement.
55
56=head2 Indented Here-documents
57
58This adds a new modifier '~' to here-docs that tells the parser
59that it should look for /^\s*$DELIM\n/ as the closing delimiter.
60
61These syntaxes are all supported:
62
63 <<~EOF;
64 <<~\EOF;
65 <<~'EOF';
66 <<~"EOF";
67 <<~`EOF`;
68 <<~ 'EOF';
69 <<~ "EOF";
70 <<~ `EOF`;
71
72The '~' modifier will strip, from each line in the here-doc, the
73same whitespace that appears before the delimiter.
74
fce64130 75Newlines will be copied as-is, and lines that don't include the
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76proper beginning whitespace will cause perl to croak.
77
78For example:
79
80 if (1) {
81 print <<~EOF;
82 Hello there
83 EOF
84 }
85
86prints "Hello there\n" with no leading whitespace.
87
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88=head2 @{^CAPTURE}, %{^CAPTURE}, and %{^CAPTURE_ALL}
89
90C<@{^CAPTURE}> exposes the capture buffers of the last match as an
95b17558 91array. So C<$1> is C<${^CAPTURE}[0]>. This is a more efficient equivalent
95013431 92to code like C<substr($matched_string,$-[0],$+[0]-$-[0])>, and you don't
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93have to keep track of the C<$matched_string> either. This variable has no
94single character equivalent. Note, like the other regex magic variables
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95the contents of this variable is dynamic, if you wish to store it beyond
96the lifetime of the match you must copy it to another array.
2c8edc25 97
95b17558 98C<%{^CAPTURE}> is the equivalent to C<%+> (I<i.e.>, named captures). Other than
95013431 99being more self documenting there is no difference between the two forms.
2c8edc25 100
fce64130 101C<%{^CAPTURE_ALL}> is the equivalent to C<%-> (I<i.e.>, all named captures).
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102Other than being more self documenting there is no difference between the
103two forms.
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104
105=head2 Unicode 9.0 is now supported
106
107A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
108Modules that are shipped with core Perl but not maintained by p5p do not
109necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
110
111=head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
112
113Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and
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114called it Script_Extensions (C<scx>). Perl now uses this improved
115version when a property is specified as just C<\p{I<script>}>. This
116should make programs be more accurate when determining if a character is
117used in a given script, but there is a slight chance of breakage for
118programs that very specifically needed the old behavior. The meaning of
119compound forms, like C<\p{sc=I<script>}> are unchanged. See
120L<perlunicode/Scripts>.
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121
122=head2 Declaring a reference to a variable
123
124As an experimental feature, Perl now allows the referencing operator to come
125after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
126L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
127be enabled with C<use feature 'declared_refs'>. It is experimental, and will
128warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
129It is intended mainly for use in assignments to references. For example:
130
131 use experimental 'refaliasing', 'declared_refs';
132 my \$a = \$b;
133
a9fbda47 134See L<perlref/Assigning to References> for more details.
a049258c 135
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136=head2 Perl can now do default collation in UTF-8 locales on platforms
137that support it
a049258c 138
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139Some platforms natively do a reasonable job of collating and sorting in
140UTF-8 locales. Perl now works with those. For portability and full
141control, L<Unicode::Collate> is still recommended, but now you may
142not need to do anything special to get good-enough results, depending on
143your application. See
144L<perllocale/Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>.
145
146=head2 Better locale collation of strings containing embedded C<NUL>
147characters
148
fce64130 149In locales that have multi-level character weights, C<NUL>s are now
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150ignored at the higher priority ones. There are still some gotchas in
151some strings, though. See
152L<perllocale/Collation of strings containing embedded C<NUL> characters>.
153
154=head2 Lexical subroutines are no longer experimental
155
95b17558 156Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
2c8edc25 157code that disables the C<experimental::lexical_subs> warning category
95b17558 158that the feature previously used will continue to work. The
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159C<lexical_subs> feature has no effect; all Perl code can use lexical
160subroutines, regardless of what feature declarations are in scope.
161
162=head2 C<CORE> subroutines for hash and array functions callable via
163reference
164
165The hash and array functions in the C<CORE> namespace--C<keys>, C<each>,
166C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>--, can now
167be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference
e6abae1c 168(C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be
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169used when inlined.
170
8b70433f 171=head2 for XS code, create a safer utf8_hop() called utf8_hop_safe()
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172
173Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after
174the end of the supplied buffer.
175
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176=head1 Security
177
89853d76 178=head2 Removal of the current directory (C<.>) from C<@INC>
2c8edc25 179
95b17558 180The perl binary includes a default set of paths in C<@INC>. Historically
89853d76 181it has also included the current directory (C<.>) as the final entry,
95b17558 182unless run with taint mode enabled (C<perl -T>). While convenient, this has
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183security implications: for example, where a script attempts to load an
184optional module when its current directory is untrusted (such as F</tmp>),
185it could load and execute code from under that directory.
186
53799a91 187Starting with v5.26, C<.> is always removed by default, not just under
95b17558 188tainting. This has major implications for installing modules and executing
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189scripts.
190
191The following new features have been added to help ameliorate these
192issues.
193
194=over
195
196=item * C<Configure -Udefault_inc_excludes_dot>
197
198There is a new C<Configure> option, C<default_inc_excludes_dot> (enabled
199by default) which builds a perl executable without C<.>; unsetting this
95b17558 200option using C<-U> reverts perl to the old behaviour. This may fix your
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201path issues but will reintroduce all the security concerns, so don't
202build a perl executable like this unless you're I<really> confident that
203such issues are not a concern in your environment.
204
409c12ef 205=item * C<PERL_USE_UNSAFE_INC>
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206
207There is a new environment variable recognised by the perl interpreter.
208If this variable has the value C<1> when the perl interpreter starts up,
209then C<.> will be automatically appended to C<@INC> (except under tainting).
210
211This allows you restore the old perl interpreter behaviour on a
95b17558 212case-by-case basis. But note that this is intended to be a temporary crutch,
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213and this feature will likely be removed in some future perl version.
214It is currently set by the C<cpan> utility and C<Test::Harness> to
fce64130 215ease installation of CPAN modules which have not been updated to handle the
95b17558 216lack of dot. Once again, don't use this unless you are sure that this
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217will not reintroduce any security concerns.
218
219=item * A new mandatory warning issued by C<do>.
220
221While it is well-known that C<use> and C<require> use C<@INC> to search
222for the file to load, many people don't realise that C<do "file"> also
95b17558 223searches C<@INC> if the file is a relative path. With the removal of C<.>,
89853d76 224a simple C<do "file.pl"> will fail to read in and execute C<file.pl> from
95b17558 225the current directory. Since this is commonly expected behaviour, a new
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226mandatory warning is now issued whenever C<do> fails to load a file which
227it otherwise would have found if dot had been in C<@INC>.
228
229=back
230
231Here are some things script and module authors may need to do to make
232their software work in the new regime.
233
234=over
235
236=item * Script authors
237
238If the issue is within your own code (rather than within included
95b17558 239modules), then you have two main options. Firstly, if you are confident
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240that your script will only be run within a trusted directory (under which
241you expect to find trusted files and modules), then add C<.> back into the
fce64130 242path; I<e.g.>:
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243
244 BEGIN {
245 my $dir = "/some/trusted/directory";
246 chdir $dir or die "Can't chdir to $dir: $!\n";
247 # safe now
248 push @INC, '.';
249 }
250 use "Foo::Bar"; # may load /some/trusted/directory/Foo/Bar.pm
251 do "config.pl"; # may load /some/trusted/directory/config.pl
252
253On the other hand, if your script is intended to be run from within
254untrusted directories (such as F</tmp>), then your script suddenly failing
95b17558 255to load files may be indicative of a security issue. You most likely want
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256to replace any relative paths with full paths; for example,
257
258 do ".foo_config.pl"
259
260might become
261
262 do "$ENV{HOME}/.foo_config.pl"
263
264If you are absolutely certain that you want your script to load and
265execute a file from the current directory, then use a C<./> prefix; for
266example:
267
268 do "./.foo_config.pl"
269
270=item * Installing and using CPAN modules
271
272If you install a CPAN module using an automatic tool like C<cpan>, then
273this tool will itself set the C<PERL_USE_UNSAFE_INC> environment variable
274while building and testing the module, which may be sufficient to install
275a distribution which hasn't been updated to be dot-aware. If you want to
276install such a module manually, then you'll need to replace the
277traditional invocation:
278
279 perl Makefile.PL && make && make test && make install
280
281with something like
282
283 (export PERL_USE_UNSAFE_INC=1; \
284 perl Makefile.PL && make && make test && make install)
285
95b17558 286Note that this only helps build and install an unfixed module. It's
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287possible for the tests to pass (since they were run under
288C<PERL_USE_UNSAFE_INC=1>), but for the module itself to fail to perform
95b17558 289correctly in production. In this case you may have to temporarily modify
0f275d26 290your script until such time as a fixed version of the module is released.
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291For example:
292
293 use Foo::Bar;
294 {
295 local @INC = (@INC, '.');
296 # assuming read_config() needs '.' in @INC
297 $config = Foo::Bar->read_config();
298 }
299
95b17558 300This is only rarely expected to be necessary. Again, if doing this,
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301assess the resultant risks first.
302
303=item * Module Authors
304
305If you maintain a CPAN distribution, it may need updating to run in
95b17558 306a dotless environment. Although C<cpan> and other such tools will
0f275d26 307currently set the C<PERL_USE_UNSAFE_INC> during module build, this is a
89853d76 308temporary workaround for the set of modules which rely on C<.> being in
95b17558 309C<@INC> for installation and testing, and this may mask deeper issues. It
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310could result in a module which passes tests and installs, but which
311fails at run time.
312
313During build, test and install, it will normally be the case that any perl
314processes will be executing directly within the root directory of the
95b17558 315untarred distribution, or a known subdirectory of that, such as F<t/>. It
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316may well be that F<Makefile.PL> or F<t/foo.t> will attempt to include
317local modules and configuration files using their direct relative
318filenames, which will now fail.
319
320However, as described above, automatic tools like F<cpan> will (for now)
321set the C<PERL_USE_UNSAFE_INC> environment variable, which introduces
322dot during build.
323
324This makes it likely that your existing build and test code will work, but
325this may mask issues with your code which only manifest when used after
95b17558 326install. It is prudent to try and run your build process with that
89853d76 327variable explicitly disabled:
0f275d26 328
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329 (export PERL_USE_UNSAFE_INC=0; \
330 perl Makefile.PL && make && make test && make install)
331
332This is more likely to show up any potential problems with your module's
95b17558 333build process, or even with the module itself. Fixing such issues will
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334ensure both that your module can again be installed manually, and that
335it will still build once the C<PERL_USE_UNSAFE_INC> crutch goes away.
336
337When fixing issues in tests due to the removal of dot from C<@INC>,
338reinsertion of dot into C<@INC> should be performed with caution, for this
95b17558 339too may suppress real errors in your runtime code. You are encouraged
89853d76 340wherever possible to apply the aforementioned approaches with explicit
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341absolute/relative paths, or to relocate your needed files into a
342subdirectory and insert that subdirectory into C<@INC> instead.
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343
344If your runtime code has problems under the dotless C<@INC>, then the comments
95b17558 345above on how to fix for script authors will mostly apply here too. Bear in
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346mind though that it is considered bad form for a module to globally add dot to
347C<@INC>, since it introduces both a security risk and hides issues of
348accidentally requiring dot in C<@INC>, as explained above.
349
350=back
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351
352=head2 "Escaped" colons and relative paths in PATH
353
354On Unix systems, Perl treats any relative paths in the PATH environment
355variable as tainted when starting a new process. Previously, it was
356allowing a backslash to escape a colon (unlike the OS), consequently
357allowing relative paths to be considered safe if the PATH was set to
358something like C</\:.>. The check has been fixed to treat C<.> as tainted
359in that example.
360
361=head2 C<-Di> switch is now required for PerlIO debugging output
362
363Previously PerlIO debugging output would be sent to the file specified
364by the C<PERLIO_DEBUG> environment variable if perl wasn't running
365setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
366
367If perl performed output at a point where it hadn't yet parsed its
368switches this could result in perl creating or overwriting the file
369named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
370
371Perl now requires the C<-Di> switch to produce PerlIO debugging
372output. By default this is written to C<stderr>, but can optionally
373be redirected to a file by setting the C<PERLIO_DEBUG> environment
374variable.
a049258c 375
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376If perl is running setuid or the C<-T> switch has supplied
377C<PERLIO_DEBUG> is ignored and the debugging output is sent to
378C<stderr> as for any other C<-D> switch.
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379
380=head1 Incompatible Changes
381
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382=head2 Unescaped literal C<"{"> characters in regular expression
383patterns are no longer permissible
a049258c 384
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385You have to now say something like C<"\{"> or C<"[{]"> to specify to
386match a LEFT CURLY BRACKET; otherwise it is a fatal pattern compilation
387error. This change will allow future extensions to the language.
388
389These have been deprecated since v5.16, with a deprecation message
390raised for some uses starting in v5.22. Unfortunately, the code added
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391to raise the message was buggy, and failed to warn in some cases where
392it should have. Therefore, enforcement of this ban for these cases is
393deferred until Perl 5.30, but the code has been fixed to raise a
394default-on deprecation message for them in the meantime.
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395
396Some uses of literal C<"{"> occur in contexts where we do not foresee
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397the meaning ever being anything but the literal, such as the very first
398character in the pattern, or after a C<"|"> meaning alternation. Thus
399
400 qr/{fee|{fie/
401
402matches either of the strings C<{fee> or C<{fie>. To avoid forcing
403unnecessary code changes, these uses do not need to be escaped, and no
404warning is raised about them, and there are no current plans to change this.
405
406But it is always correct to escape C<"{">, and the simple rule to
407remember is to always do so.
a049258c 408
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409=head2 C<scalar(%hash)> return signature changed
410
411The value returned for C<scalar(%hash)> will no longer show information about
412the buckets allocated in the hash. It will simply return the count of used
413keys. It is thus equivalent to C<0+keys(%hash)>.
414
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415A form of backwards compatibility is provided via
416L<C<Hash::Util::bucket_ratio()>|Hash::Util/bucket_ratio> which provides
417the same behavior as
418C<scalar(%hash)> provided in Perl 5.24 and earlier.
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419
420=head2 C<keys> returned from an lvalue subroutine
421
422C<keys> returned from an lvalue subroutine can no longer be assigned
423to in list context.
424
425 sub foo : lvalue { keys(%INC) }
426 (foo) = 3; # death
427 sub bar : lvalue { keys(@_) }
428 (bar) = 3; # also an error
429
430This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
431C<(keys @_) = ...>, which are also errors. [perl #128187]
a049258c 432
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433=head2 C<${^ENCODING}> has been removed
434
435Consequently, the L<encoding> pragma's default mode is no longer supported. If
436you still need to write your source code in encodings other than UTF-8, use a
437source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
438option.
439
440=head2 POSIX::tmpnam() has been removed
441
442The fundamentally unsafe C<tmpnam()> interface was deprecated in
53799a91 443Perl 5.22 and has now been removed. In its place you can use,
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444for example, the L<File::Temp> interfaces.
445
446=head2 require ::Foo::Bar is now illegal.
447
95b17558 448Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
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449bareword require which starts with a double colon dies instead.
450
451=head2 Literal control character variable names are no longer permissible
452
453A variable name may no longer contain a literal control character under
454any circumstances. These previously were allowed in single-character
455names on ASCII platforms, but have been deprecated there since Perl
4565.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
457control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
458source code.
459
460=head2 C<NBSP> is no longer permissible in C<\N{...}>
461
462The name of a character may no longer contain non-breaking spaces. It
53799a91 463has been deprecated to do so since Perl 5.22.
8d25d2f3 464
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465=head1 Deprecations
466
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467=head2 String delimiters that aren't stand-alone graphemes are now deprecated
468
469In order for Perl to eventually allow string delimiters to be Unicode
470grapheme clusters (which look like a single character, but may be
0f275d26 471a sequence of several ones), we have to stop allowing a single character
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472delimiter that isn't a grapheme by itself. These are unlikely to exist
473in actual code, as they would typically display as attached to the
474character in front of them.
475
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476=head1 Removed Deprecations
477
478The C<\cI<X>> construct is intended to be a way to specify non-printable
479characters. Previously it was deprecated to use it for a printable one,
480which is better written as simply itself, perhaps preceded by a
481backslash for non-word characters. Now this raises a warning, but not a
482deprecation. See
483L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>.
484
2c8edc25 485=head1 Performance Enhancements
a049258c 486
2c8edc25 487=over 4
a049258c 488
2c8edc25 489=item *
a049258c 490
fce64130 491A hash in boolean context is now sometimes faster, I<e.g.>
a049258c 492
2c8edc25 493 if (!%h) { ... }
a049258c 494
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495This was already special-cased, but some cases were missed, and even the
496ones which weren't have been improved.
a049258c 497
2c8edc25 498=item *
a049258c 499
2c8edc25 500Several other ops may now also be faster in boolean context.
a049258c 501
2c8edc25 502=item * New Faster Hash Function on 64 bit builds
a049258c 503
95b17558 504We use a different hash function for short and long keys. This should
2c8edc25 505improve performance and security, especially for long keys.
a049258c 506
2c8edc25 507=item * readline is faster
a049258c 508
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509Reading from a file line-by-line with C<readline()> or C<< E<lt>E<gt> >> should
510now typically be faster due to a better implementation of the code that
511searches for the next newline character.
512
513=item *
a049258c 514
2c8edc25 515Reduce cost of SvVALID().
a049258c 516
2c8edc25 517=item *
ad5c8857 518
2c8edc25 519C<$ref1 = $ref2> has been optimized.
5e50eae4 520
4b99a68c 521=item *
f4b40f11 522
fce64130 523Array and hash assignment are now faster, I<e.g.>
ec34c8a4 524
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525 (..., @a) = (...);
526 (..., %h) = (...);
f4b40f11 527
2c8edc25 528especially when the RHS is empty.
ec34c8a4 529
2c8edc25 530=item *
a049258c 531
2c8edc25 532Reduce the number of odd special cases for the C<SvSCREAM> flag.
e770df11 533
2c8edc25 534=item *
a049258c 535
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536Avoid sv_catpvn() in do_vop() when unneeded.
537
538=item *
539
540Enhancements in Regex concat COW implementation.
541
542=item *
543
95b17558 544Clearing hashes and arrays has been made slightly faster. Now code
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545like this is around 5% faster:
546
547 my @a;
548 for my $i (1..3_000_000) {
549 @a = (1,2,3);
550 @a = ();
551 }
552
553and this code around 3% faster:
554
555 my %h;
556 for my $i (1..3_000_000) {
557 %h = qw(a 1 b 2);
558 %h = ();
559 }
2c8edc25
S
560
561=item *
562
563Better optimise array and hash assignment
564
565=item *
566
567Converting a single-digit string to a number is now substantially faster.
568
569=item *
570
571The internal op implementing the C<split> builtin has been simplified and
95b17558
KW
572sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
573to do its work. Secondly, code of the form C<my @x = split(...)> is now
2c8edc25
S
574optimised in the same way as C<@x = split(...)>, and is therefore a few
575percent faster.
576
577=item *
578
579The rather slow implementation for the experimental subroutine signatures
580feature has been made much faster; it is now comparable in speed with the
581old-style C<my ($a, $b, @c) = @_>.
7ca0bfc4 582
fbe3f407
S
583=item *
584
2c8edc25 585Bareword constant strings are now permitted to take part in constant
95b17558 586folding. They were originally exempted from constant folding in August 1999,
2c8edc25 587during the development of Perl 5.6, to ensure that C<use strict "subs">
95b17558 588would still apply to bareword constants. That has now been accomplished a
2c8edc25
S
589different way, so barewords, like other constants, now gain the performance
590benefits of constant folding.
591
592This also means that void-context warnings on constant expressions of
593barewords now report the folded constant operand, rather than the operation;
594this matches the behaviour for non-bareword constants.
a049258c
S
595
596=back
597
2c8edc25
S
598=head1 Modules and Pragmata
599
a049258c
S
600=head2 Updated Modules and Pragmata
601
602=over 4
fbe3f407 603
759020c9 604=item *
7ca0bfc4 605
0cc8c746
S
606L<Archive::Tar> has been upgraded from version 2.04 to 2.24.
607
608=item *
609
610L<arybase> has been upgraded from version 0.11 to 0.12.
611
612=item *
613
614L<attributes> has been upgraded from version 0.27 to 0.29.
a049258c 615
2c8edc25 616The deprecation message for the C<:unique> and C<:locked> attributes
0f275d26 617now mention that they will disappear in Perl 5.28.
a049258c 618
2c8edc25 619=item *
a049258c 620
0cc8c746
S
621L<B> has been upgraded from version 1.62 to 1.68.
622
623=item *
624
625L<B::Concise> has been upgraded from version 0.996 to 0.999.
2c8edc25
S
626
627Its output is now more descriptive for C<op_private> flags.
d5c7a4fc 628
759020c9
S
629=item *
630
0cc8c746
S
631L<B::Debug> has been upgraded from version 1.23 to 1.24.
632
633=item *
634
635L<B::Deparse> has been upgraded from version 1.37 to 1.40.
636
637=item *
638
2c8edc25 639L<B::Xref> has been upgraded from version 1.05 to 1.06.
a049258c 640
2c8edc25 641It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 642
2c8edc25 643=item *
a049258c 644
0cc8c746
S
645L<base> has been upgraded from version 2.23 to 2.25.
646
647=item *
648
649L<bignum> has been upgraded from version 0.42 to 0.47.
650
651=item *
652
653L<Carp> has been upgraded from version 1.40 to 1.42.
654
655=item *
656
657L<charnames> has been upgraded from version 1.43 to 1.44.
658
659=item *
660
661L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.074.
662
663=item *
664
665L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.074.
666
667=item *
668
669L<Config::Perl::V> has been upgraded from version 0.25 to 0.28.
670
671=item *
672
673L<CPAN> has been upgraded from version 2.11 to 2.18.
674
675=item *
676
677L<CPAN::Meta> has been upgraded from version 2.150005 to 2.150010.
678
679=item *
680
681L<Data::Dumper> has been upgraded from version 2.160 to 2.167.
a049258c 682
2c8edc25 683The XS implementation now supports Deparse.
a049258c 684
2c8edc25 685This fixes a stack management bug. [perl #130487].
a049258c 686
2c8edc25 687=item *
a049258c 688
0cc8c746
S
689L<DB_File> has been upgraded from version 1.835 to 1.840.
690
691=item *
692
693L<Devel::Peek> has been upgraded from version 1.23 to 1.26.
694
695=item *
696
697L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
698
699=item *
700
2c8edc25 701L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
a049258c 702
2c8edc25 703It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 704
2c8edc25 705=item *
a049258c 706
0cc8c746 707L<diagnostics> has been upgraded from version 1.34 to 1.36.
a049258c 708
2c8edc25 709It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
7ca0bfc4 710
ad5c8857 711=item *
7ca0bfc4 712
0cc8c746
S
713L<Digest> has been upgraded from version 1.17 to 1.17_01.
714
715=item *
716
717L<Digest::MD5> has been upgraded from version 2.54 to 2.55.
718
719=item *
720
721L<Digest::SHA> has been upgraded from version 5.95 to 5.96.
722
723=item *
724
725L<DynaLoader> has been upgraded from version 1.38 to 1.42.
726
727=item *
728
729L<Encode> has been upgraded from version 2.80 to 2.88.
730
731=item *
732
733L<encoding> has been upgraded from version 2.17 to 2.19.
8f7edc68 734
ee8180b8 735This module's default mode is no longer supported. It now
2c8edc25 736dies when imported, unless the C<Filter> option is being used.
d5c7a4fc 737
2c8edc25 738=item *
d5c7a4fc 739
2c8edc25 740L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
a049258c 741
ee8180b8 742This module is no longer supported. It emits a warning to
2c8edc25 743that effect and then does nothing.
a049258c 744
2c8edc25 745=item *
d5c7a4fc 746
0cc8c746 747L<Errno> has been upgraded from version 1.25 to 1.28.
a049258c 748
2c8edc25 749Document that using C<%!> loads Errno for you.
d5c7a4fc 750
2c8edc25 751It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
3abe9611 752
c714fb1f 753=item *
3ce6a296 754
2c8edc25 755L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
a049258c 756
2c8edc25 757It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 758
2c8edc25 759=item *
a049258c 760
0cc8c746
S
761L<ExtUtils::MakeMaker> has been upgraded from version 7.10_01 to 7.24.
762
763=item *
764
765L<ExtUtils::Miniperl> has been upgraded from version 1.05 to 1.06.
766
767=item *
768
769L<ExtUtils::ParseXS> has been upgraded from version 3.31 to 3.34.
770
771=item *
772
773L<ExtUtils::Typemaps> has been upgraded from version 3.31 to 3.34.
774
775=item *
776
777L<feature> has been upgraded from version 1.42 to 1.47.
2c8edc25
S
778
779Fixes the Unicode Bug in the range operator.
a049258c
S
780
781=item *
5c92a635 782
0cc8c746
S
783L<File::Copy> has been upgraded from version 2.31 to 2.32.
784
785=item *
786
787L<File::Fetch> has been upgraded from version 0.48 to 0.52.
788
789=item *
790
791L<File::Glob> has been upgraded from version 1.26 to 1.28.
d5c7a4fc 792
2c8edc25 793Issue a deprecation message for C<File::Glob::glob()>.
d5c7a4fc 794
2c8edc25 795=item *
d5c7a4fc 796
0cc8c746
S
797L<File::Spec> has been upgraded from version 3.63 to 3.67.
798
799=item *
800
801L<FileHandle> has been upgraded from version 2.02 to 2.03.
802
803=item *
804
2c8edc25 805L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
a049258c 806
2c8edc25
S
807It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
808end-of-file. [perl #107726]
64afbd29
DM
809
810=item *
811
0cc8c746
S
812L<Getopt::Long> has been upgraded from version 2.48 to 2.49.
813
814=item *
815
816L<Getopt::Std> has been upgraded from version 1.11 to 1.12.
817
818=item *
819
820L<Hash::Util> has been upgraded from version 0.19 to 0.22.
821
822=item *
823
824L<HTTP::Tiny> has been upgraded from version 0.056 to 0.070.
a049258c 825
2c8edc25 826Internal 599-series errors now include the redirect history.
a049258c 827
2c8edc25 828=item *
a049258c 829
0cc8c746 830L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
a049258c 831
2c8edc25 832It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 833
2c8edc25 834=item *
a049258c 835
0cc8c746
S
836L<IO> has been upgraded from version 1.36 to 1.38.
837
838=item *
839
601d9a87 840IO-Compress has been upgraded from version 2.069 to 2.074.
0cc8c746
S
841
842=item *
843
844L<IO::Socket::IP> has been upgraded from version 0.37 to 0.38.
845
846=item *
847
848L<IPC::Cmd> has been upgraded from version 0.92 to 0.96.
849
850=item *
851
852L<IPC::SysV> has been upgraded from version 2.06_01 to 2.07.
853
854=item *
855
856L<JSON::PP> has been upgraded from version 2.27300 to 2.27400_02.
857
858=item *
859
2c8edc25
S
860L<lib> has been upgraded from version 0.63 to 0.64.
861
862It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
faab9793 863
c714fb1f 864=item *
ad5c8857 865
0cc8c746
S
866L<List::Util> has been upgraded from version 1.42_02 to 1.46_02.
867
868=item *
869
870L<Locale::Codes> has been upgraded from version 3.37 to 3.42.
871
872=item *
873
874L<Locale::Maketext> has been upgraded from version 1.26 to 1.28.
875
876=item *
877
878L<Locale::Maketext::Simple> has been upgraded from version 0.21 to 0.21_01.
879
880=item *
881
882L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
ad5c8857 883
2c8edc25 884There have also been some core customizations.
ad5c8857 885
2c8edc25 886=item *
2e0dcc12 887
0cc8c746
S
888L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
889
890=item *
891
892L<Math::BigRat> has been upgraded from version 0.260802 to 0.2611.
893
894=item *
895
896L<Math::Complex> has been upgraded from version 1.59 to 1.5901.
897
898=item *
899
900L<Memoize> has been upgraded from version 1.03 to 1.03_01.
901
902=item *
903
904L<Module::CoreList> has been upgraded from version 5.20170420 to 5.20170520.
905
906=item *
907
908L<Module::Load::Conditional> has been upgraded from version 0.64 to 0.68.
909
910=item *
911
912L<Module::Metadata> has been upgraded from version 1.000031 to 1.000033.
913
914=item *
915
916L<mro> has been upgraded from version 1.18 to 1.20.
917
918=item *
919
920L<Net::Ping> has been upgraded from version 2.43 to 2.55.
d5c7a4fc 921
2c8edc25
S
922IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
923other enhancements.
d5c7a4fc 924
2c8edc25
S
925Remove sudo from 500_ping_icmp.t.
926
927Avoid stderr noise in tests
928
0f275d26 929Check for echo in new L<Net::Ping> tests.
d5c7a4fc 930
a049258c 931=item *
d5c7a4fc 932
0cc8c746
S
933L<NEXT> has been upgraded from version 0.65 to 0.67.
934
935=item *
936
937L<Opcode> has been upgraded from version 1.34 to 1.39.
938
939=item *
940
941L<open> has been upgraded from version 1.10 to 1.11.
942
943=item *
944
2c8edc25 945L<OS2::Process> has been upgraded from version 1.11 to 1.12.
a049258c 946
2c8edc25 947It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 948
2c8edc25 949=item *
a049258c 950
2c8edc25 951L<overload> has been upgraded from version 1.26 to 1.28.
a049258c 952
2c8edc25 953Its compilation speed has been improved slightly.
a049258c 954
2c8edc25
S
955=item *
956
0cc8c746
S
957L<parent> has been upgraded from version 0.234 to 0.236.
958
959=item *
960
2c8edc25
S
961L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
962
963Ignore F</dev/tty> on non-Unix systems. [perl #113960]
964
965=item *
966
0cc8c746
S
967L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
968
969=item *
970
971L<perlfaq> has been upgraded from version 5.021010 to 5.021011.
972
973=item *
974
975L<PerlIO> has been upgraded from version 1.09 to 1.10.
976
977=item *
978
979L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
980
981=item *
982
983L<PerlIO::scalar> has been upgraded from version 0.24 to 0.26.
984
985=item *
986
987L<Pod::Checker> has been upgraded from version 1.60 to 1.73.
988
989=item *
990
991L<Pod::Functions> has been upgraded from version 1.10 to 1.11.
992
993=item *
994
995L<Pod::Html> has been upgraded from version 1.22 to 1.2202.
996
997=item *
998
999L<Pod::Perldoc> has been upgraded from version 3.25_02 to 3.28.
1000
1001=item *
1002
1003L<Pod::Simple> has been upgraded from version 3.32 to 3.35.
1004
1005=item *
1006
1007L<Pod::Usage> has been upgraded from version 1.68 to 1.69.
1008
1009=item *
1010
95b17558 1011L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
2c8edc25
S
1012defects in making its symbols exportable. [perl #127821]
1013The C<POSIX::tmpnam()> interface has been removed,
1014see L</"POSIX::tmpnam() has been removed">.
1015Trying to import POSIX subs that have no real implementations
1016(like C<POSIX::atend()>) now fails at import time, instead of
1017waiting until runtime.
1018
1019=item *
1020
0cc8c746 1021L<re> has been upgraded from version 0.32 to 0.34
2c8edc25
S
1022
1023This adds support for the new L<C<E<47>xx>|perlre/E<sol>x and E<sol>xx>
1024regular expression pattern modifier, and a change to the L<S<C<use re
1025'strict'>>|re/'strict' mode> experimental feature. When S<C<re
1026'strict'>> is enabled, a warning now will be generated for all
1027unescaped uses of the two characters C<}> and C<]> in regular
1028expression patterns (outside bracketed character classes) that are taken
1029literally. This brings them more in line with the C<)> character which
1030is always a metacharacter unless escaped. Being a metacharacter only
1031sometimes, depending on action at a distance, can lead to silently
1032having the pattern mean something quite different than was intended,
1033which the S<C<re 'strict'>> mode is intended to minimize.
1034
1035=item *
1036
0cc8c746
S
1037L<Safe> has been upgraded from version 2.39 to 2.40.
1038
1039=item *
1040
1041L<Scalar::Util> has been upgraded from version 1.42_02 to 1.46_02.
1042
1043=item *
1044
1045L<Storable> has been upgraded from version 2.56 to 2.62.
2c8edc25
S
1046
1047Fixes [perl #130098].
1048
1049=item *
1050
0cc8c746
S
1051L<Symbol> has been upgraded from version 1.07 to 1.08.
1052
1053=item *
1054
1055L<Sys::Syslog> has been upgraded from version 0.33 to 0.35.
1056
1057=item *
1058
1059L<Term::ANSIColor> has been upgraded from version 4.04 to 4.06.
1060
1061=item *
1062
2c8edc25
S
1063L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
1064
1065It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1066
1067=item *
1068
0cc8c746 1069L<Test> has been upgraded from version 1.28 to 1.30.
2c8edc25
S
1070
1071It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1072
1073=item *
1074
0cc8c746
S
1075L<Test::Harness> has been upgraded from version 3.36 to 3.38.
1076
1077=item *
1078
1079L<Test::Simple> has been upgraded from version 1.001014 to 1.302073.
1080
1081=item *
1082
1083L<Thread::Queue> has been upgraded from version 3.09 to 3.12.
1084
1085=item *
1086
2c8edc25
S
1087L<Thread::Semaphore> has been upgraded from 2.12 to 2.13.
1088
1089Added the C<down_timed> method.
1090
1091=item *
1092
0cc8c746 1093L<threads> has been upgraded from version 2.07 to 2.15.
2c8edc25
S
1094
1095Compatibility with 5.8 has been restored.
1096
1097Fixes [perl #130469].
1098
1099=item *
1100
0cc8c746 1101L<threads::shared> has been upgraded from version 1.51 to 1.56.
2c8edc25
S
1102
1103This fixes [cpan #119529], [perl #130457]
1104
1105=item *
1106
0cc8c746
S
1107L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
1108
1109=item *
1110
1111L<Time::HiRes> has been upgraded from version 1.9733 to 1.9741.
2c8edc25
S
1112
1113It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
11143.9).
1115
1116Now uses C<clockid_t>.
1117
1118=item *
1119
0cc8c746
S
1120L<Time::Local> has been upgraded from version 1.2300 to 1.25.
1121
1122=item *
1123
1124L<Unicode::Collate> has been upgraded from version 1.14 to 1.19.
1125
1126=item *
1127
1128L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
2c8edc25
S
1129
1130It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1131
1132=item *
1133
0cc8c746
S
1134L<version> has been upgraded from version 0.9916 to 0.9917.
1135
1136=item *
1137
1138L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
2c8edc25
S
1139
1140It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1141
1142=item *
1143
0cc8c746
S
1144L<warnings> has been upgraded from version 1.36 to 1.37.
1145
1146=item *
1147
1148L<XS::Typemap> has been upgraded from version 0.14 to 0.15.
1149
1150=item *
1151
1152L<XSLoader> has been upgraded from version 0.21 to 0.27.
2c8edc25
S
1153
1154Fixed a security hole in which binary files could be loaded from a path
1155outside of L<C<@INC>|perlvar/@INC>.
1156
1157It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1158
1159=back
1160
2c8edc25
S
1161=head1 Documentation
1162
1163=head2 New Documentation
a049258c 1164
2c8edc25 1165=head3 L<perldeprecation>
a049258c 1166
2c8edc25 1167This file documents all upcoming deprecations, and some of the deprecations
95b17558 1168which already have been removed. The purpose of this documentation is
2c8edc25
S
1169two-fold: document what will disappear, and by which version, and serve
1170as a guide for people dealing with code which has features that no longer
1171work after an upgrade of their perl.
a049258c 1172
2c8edc25 1173=head2 Changes to Existing Documentation
a049258c 1174
2c8edc25 1175=head3 L<perlcall>
a049258c
S
1176
1177=over 4
1178
2c8edc25
S
1179=item *
1180
1181Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30
a049258c 1182
2c8edc25
S
1183This was changed to drop a leading C<v> in C<v5.30>, so it uses the same
1184style as other deprecation messages.
a049258c 1185
2c8edc25
S
1186=item *
1187
1188"\c%c" is more clearly written simply as "%s".
1189
1190It 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>
1191
1192=item *
1193
1194Removed redundant C<dSP> from an example.
a049258c 1195
2c8edc25 1196=back
a049258c 1197
2c8edc25 1198=head3 L<perlcommunity>
a049258c
S
1199
1200=over 4
1201
2c8edc25 1202=item *
a049258c 1203
2c8edc25 1204All references to Usenet have been removed.
a049258c
S
1205
1206=back
1207
2c8edc25
S
1208=head3 L<perldata>
1209
1210=over 4
1211
1212=item *
1213
1214Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
1215signature changed> above.
1216
1217=item *
a049258c 1218
2c8edc25 1219Use of single character variables, with the variable name a non printable
95b17558 1220character in the range C<\x80>-C<\xFF> is no longer allowed. Update the docs to
2c8edc25
S
1221reflect this.
1222
1223=back
1224
1225=head3 L<perldelta>
a049258c
S
1226
1227=over 4
1228
2c8edc25 1229=item *
a049258c 1230
2c8edc25 1231All references to Usenet have been removed.
a049258c
S
1232
1233=back
1234
2c8edc25
S
1235=head3 L<perldiag>
1236
1237=over 4
1238
1239=item *
1240
1241Deprecations are to be marked with a D.
1242C<"%s() is deprecated on :utf8 handles"> use a deprecation message, and as
1243such, such be marked C<"(D deprecated)"> and not C<"(W deprecated)">.
a049258c 1244
2c8edc25 1245=back
a049258c 1246
2c8edc25 1247=head3 L<perlexperiment>
a049258c
S
1248
1249=over 4
1250
1251=item *
1252
2c8edc25 1253Documented new feature: See L</Declaring a reference to a variable> above.
a049258c
S
1254
1255=back
1256
2c8edc25
S
1257=head3 L<perlfunc>
1258
1259=over 4
1260
1261=item *
1262
95b17558 1263Defined on aggregates is no longer allowed. Perlfunc was still reporting it as
2c8edc25
S
1264deprecated, and that it will be deleted in the future.
1265
1266=item *
1267
1268Clarified documentation of L<C<seek()>|perlfunc/seek>,
1269L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>.
1270L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
a049258c 1271
2c8edc25
S
1272=item *
1273
1274Removed obsolete documentation of L<C<study()>|perlfunc/study>.
1275
1276=back
a049258c 1277
2c8edc25 1278=head3 L<perlguts>
a049258c
S
1279
1280=over 4
1281
1282=item *
1283
2c8edc25 1284Add C<pTHX_> to magic method examples.
a049258c
S
1285
1286=back
1287
2c8edc25
S
1288=head3 L<perlhack>
1289
1290=over 4
1291
1292=item *
1293
1294Document Tab VS Space.
a049258c 1295
2c8edc25 1296=back
a049258c 1297
2c8edc25 1298=head3 L<perlinterp>
a049258c
S
1299
1300=over 4
1301
1302=item *
1303
2c8edc25
S
1304L<perlinterp> has been expanded to give a more detailed example of how to
1305hunt around in the parser for how a given operator is handled.
a049258c
S
1306
1307=back
1308
2c8edc25 1309=head3 L<perllocale>
a049258c
S
1310
1311=over 4
1312
1313=item *
1314
2c8edc25
S
1315Document C<NUL> collation handling.
1316
1317=item *
1318
1319Some locales aren't compatible with Perl. Note the potential bad
1320consequences of using them.
a049258c
S
1321
1322=back
1323
2c8edc25
S
1324=head3 L<perlmodinstall>
1325
1326=over 4
1327
1328=item *
1329
1330All references to Usenet have been removed.
1331
1332=back
1333
1334=head3 L<perlmodlib>
1335
1336=over 4
1337
1338=item *
1339
1340Updated the mirror list.
1341
1342=item *
1343
1344All references to Usenet have been removed.
1345
1346=back
1347
1348=head3 L<perlnewmod>
1349
1350=over 4
1351
1352=item *
1353
1354All references to Usenet have been removed.
1355
1356=back
1357
1358=head3 L<perlobj>
1359
1360=over 4
1361
1362=item *
1363
1364Added a section on calling methods using their fully qualified names.
1365
1366=item *
1367
1368Do not discourage manual @ISA.
1369
1370=back
1371
1372=head3 L<perlootut>
1373
1374=over 4
1375
1376=item *
1377
1378Tidy the document.
1379
1380=item *
1381
1382Mention C<Moo> more.
1383
1384=back
1385
1386=head3 L<perlop>
1387
1388=over 4
1389
1390=item *
1391
0f275d26 1392Clarify behavior of single quote regexps.
2c8edc25
S
1393
1394=back
1395
1396=head3 L<perlre>
1397
1398=over 4
1399
1400=item *
1401
1c34b59a
KW
1402The first part was extensively rewritten to incorporate various basic
1403points, that in earlier versions were mentioned in sort of an appendix
1404on Version 8 regular expressions.
1405
2c8edc25
S
1406Several minor enhancements to the documentation.
1407
1408=back
1409
1410=head3 L<perlsec>
1411
1412=over 4
1413
1414=item *
1415
1416Fixed link to Crosby paper on hash complexity attack.
1417
1418=back
1419
1420=head3 L<perlref>
1421
1422=over 4
1423
1424=item *
1425
1426Documented new feature: See L</Declaring a reference to a variable> above.
1427
1428=back
1429
1430=head3 L<perltie>
1431
1432=over 4
1433
1434=item *
1435
1436Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
1437signature changed> above.
1438
1439=back
1440
1441=head3 L<perlunicode>
1442
1443=over 4
1444
1445=item *
1446
1447Documented change to C<\p{I<script>}> to now use the improved Script_Extensions
1448property. See L</Use of \p{script} uses the improved Script_Extensions
1449property> above.
1450
1451=item *
1452
1453Updated the text to correspond with changes in Unicode UTS#18, concerning
1454regular expressions, and Perl compatibility with what it says.
1455
1456=back
1457
1458=head3 L<perlvar>
1459
1460=over 4
1461
1462=item *
1463
1464Removed obsolete documentation of C<${^ENCODING}>. See L</${^ENCODING} has
1465been removed> above.
1466
1467=item *
1468
95b17558 1469Document C<@ISA>. Was documented other places, not not in L<perlvar>.
2c8edc25
S
1470
1471=back
1472
1473=head1 Diagnostics
1474
1475=head2 New Diagnostics
1476
1477=head3 New Errors
1478
1479=over 4
1480
1481=item *
1482
1483Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1484a warning recommending to fix the C<do> statement:
1485
1486L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
1487
1488=item *
1489
1490Using the empty pattern (which re-executes the last successfully-matched
1491pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
95b17558 1492always previously yielded a segfault. It now produces an error:
4f73c567 1493L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
2c8edc25
S
1494
1495=item *
1496
1497L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
1498
1499(F) To declare references to variables, as in C<my \%x>, you must first enable
1500the feature:
1501
1502 no warnings "experimental::declared_refs";
1503 use feature "declared_refs";
1504
1505=item *
1506
1507L<Version control conflict marker|perldiag/"Version control conflict marker">
1508
e6abae1c 1509(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
95b17558 1510C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
2c8edc25
S
1511version control system to mark conflicts after a failed merge operation.
1512
1513=item *
1514
1515L<%s: command not found|perldiag/"%s: command not found">
1516
1517(A) You've accidentally run your script through B<bash> or another shell
1518instead of Perl. Check the #! line, or manually feed your script into
1519Perl yourself. The #! line at the top of your file could look like:
1520
1521 #!/usr/bin/perl
1522
1523=item *
1524
1525L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1526
1527(A) You've accidentally run your script through B<zsh> or another shell
1528instead of Perl. Check the #! line, or manually feed your script into
1529Perl yourself. The #! line at the top of your file could look like:
1530
1531 #!/usr/bin/perl
1532
1533=item *
1534
d8362e1b 1535L<Unescaped left brace in regex is illegal here|perldiag/Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in m/%s/>
2c8edc25 1536
d8362e1b
KW
1537Unescaped left braces are now illegal in some contexts in regular expression
1538patterns. In other contexts, they are still just deprecated; they will
1539be illegal in Perl 5.30.
2c8edc25
S
1540
1541=item *
1542
1543L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1544
1545=item *
1546
1547L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1548
1549=item *
1550
1551L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1552
1553=item *
1554
1555L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1556
1557=back
1558
1559=head3 New Warnings
1560
1561=over 4
1562
1563=item *
1564
4f73c567 1565L<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
1566
1567See L</Deprecations>
1568
1569=item *
1570
1571L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1572
1573(S experimental::declared_refs) This warning is emitted if you use a reference
1574constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1575C<local()>. Simply suppress the warning if you want to use the feature, but
1576know that in doing so you are taking the risk of using an experimental feature
1577which may change or be removed in a future Perl version:
1578
1579 no warnings "experimental::declared_refs";
1580 use feature "declared_refs";
1581 $fooref = my \$foo;
1582
1583=item *
1584
4f73c567 1585L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25 1586
0f275d26 1587The special variable C<${^ENCODING}>, formerly used to implement
53799a91 1588the C<encoding> pragma, is no longer supported as of Perl 5.26.
2c8edc25 1589
89853d76
DH
1590=item *
1591
1592Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1593a warning recommending to fix the C<do> statement:
1594
fc902710 1595L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
89853d76 1596
2c8edc25
S
1597=back
1598
1599=head2 Changes to Existing Diagnostics
1600
1601=over 4
1602
1603=item *
1604
1605When a C<require> fails, we now do not provide C<@INC> when the C<require>
1606is for a file instead of a module.
1607
1608=item *
1609
1610When C<@INC> is not scanned for a C<require> call, we no longer display
1611C<@INC> to avoid confusion.
1612
1613=item *
1614
1615Attribute "locked" is deprecated, and will disappear in Perl 5.28
1616
1617=item *
1618
1619Attribute "unique" is deprecated, and will disappear in Perl 5.28
1620
1621=item *
1622
1623Constants from lexical variables potentially modified elsewhere are
1624deprecated. This will not be allowed in Perl 5.32
1625
1626=item *
1627
1628Deprecated use of my() in false conditional. This will be a fatal error
1629in Perl 5.30
1630
1631=item *
1632
1633dump() better written as CORE::dump(). dump() will no longer be available
1634in Perl 5.30
1635
1636=item *
1637
1638${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
1639
1640=item *
1641
1642File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
1643instead.
1644
1645=item *
1646
1647%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
1648
1649=item *
1650
1651$* is no longer supported. Its use will be fatal in Perl 5.30
1652
1653=item *
1654
1655$* is no longer supported. Its use will be fatal in Perl 5.30
1656
1657=item *
1658
1659Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1660
1661=item *
1662
1663Opening filehandle %s also as a directory. This will be a fatal
1664error in Perl 5.28
1665
1666=item *
1667
1668Setting $/ to a reference to %s as a form of slurp is deprecated,
1669treating as undef. This will be fatal in Perl 5.28
1670
1671=item *
1672
1673Unescaped left brace in regex is deprecated here (and will be fatal
1674in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
1675
1676=item *
1677
1678Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1679
1680=item *
1681
1682Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1683
1684=item *
1685
1686Use of code point 0x%s is deprecated; the permissible max is 0x%s.
1687This will be fatal in Perl 5.28
1688
1689=item *
1690
1691Use of comma-less variable list is deprecated. Its use will be fatal
1692in Perl 5.28
1693
1694=item *
1695
1696Use of inherited AUTOLOAD for non-method %s() is deprecated. This
1697will be fatal in Perl 5.28
1698
1699=item *
1700
1701Use of strings with code points over 0xFF as arguments to %s operator
1702is deprecated. This will be a fatal error in Perl 5.28
1703
1704=item *
1705
1706Improve error for missing tie() package/method. This brings the error messages
1707in line with the ones used for normal method calls, despite not using
1708call_method().
1709
1710=item *
1711
1712Make the sysread()/syswrite/() etc :utf8 handle warnings default. These
1713warnings were under 'deprecated' previously.
1714
1715=item *
1716
1717'do' errors now refer to 'do' (not 'require').
1718
1719=item *
1720
1721Details as to the exact problem have been added to the diagnostics that
1722occur when malformed UTF-8 is encountered when trying to convert to a
1723code point.
1724
1725=item *
1726
1727Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
1728blames the variable for an uninitialized-value warning encountered by the
1729tied/magical code.
1730
1731=item *
1732
2c8edc25
S
1733Code like C<$x = $x . "a"> was incorrectly failing to yield a
1734L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
1735warning when C<$x> was a lexical variable with an undefined value. That has
1736now been fixed. [perl #127877]
1737
1738=item *
1739
1740When the error "Experimental push on scalar is now forbidden" is raised for
1741the hash functions C<keys>, C<each>, and C<values>, it is now followed by
1742the more helpful message, "Type of arg 1 to whatever must be hash or
1743array". [perl #127976]
1744
1745=item *
1746
1747C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
53799a91 1748argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
2c8edc25
S
1749been fixed.
1750
1751=item *
1752
1753C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
1754string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
1755bringing it into consistency with C<$$scalar>.
1756
1757=item *
1758
1759C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
1760do, but merely produce a syntax error. [perl #128171]
1761
1762=item *
1763
1764C<do> or C<require> with a reference or typeglob which, when stringified,
53799a91 1765contains a null character started crashing in Perl 5.20, but has now been
2c8edc25
S
1766fixed. [perl #128182]
1767
1768=back
1769
1770=head1 Utility Changes
1771
1772=head2 F<c2ph> and F<pstruct>
1773
1774=over 4
1775
1776=item *
1777
1778These old utilities have long since superceded by L<h2xs>, and are
1779now gone from the distribution.
1780
1781=back
1782
1783=head2 F<Porting/pod_lib.pl>
1784
1785=over 4
1786
1787=item *
1788
1789Removed spurious executable bit.
1790
1791=item *
1792
1793Account for possibility of DOS file endings.
1794
1795=back
1796
1797=head2 F<Porting/sync-with-cpan>
1798
1799=over 4
1800
1801=item *
1802
1803Many improvements
1804
1805=back
1806
1807=head2 F<perf/benchmarks>
1808
1809=over 4
1810
1811=item *
1812
1813Tidy file, rename some symbols.
1814
1815=back
1816
1817=head2 F<Porting/checkAUTHORS.pl>
1818
1819=over 4
1820
1821=item *
1822
0f275d26 1823Replace obscure character range with C<\w>.
2c8edc25
S
1824
1825=back
1826
1827=head2 F<t/porting/regen.t>
1828
1829=over 4
1830
1831=item *
1832
1833try to be more helpful when tests fail.
1834
1835=back
1836
1837=head2 F<utils/h2xs.PL>
1838
1839=over 4
1840
1841=item *
1842
1843Avoid infinite loop for enums.
1844
1845=back
1846
1847=head2 L<perlbug>
1848
1849=over 4
1850
1851=item *
1852
1853Long lines in the message body are now wrapped at 900 characters, to stay
1854well within the 1000-character limit imposed by SMTP mail transfer agents.
1855This is particularly likely to be important for the list of arguments to
1856C<Configure>, which can readily exceed the limit if, for example, it names
95b17558 1857several non-default installation paths. This change also adds the first unit
2c8edc25
S
1858tests for perlbug. [perl #128020]
1859
1860=back
1861
1862=head1 Configuration and Compilation
1863
1864=over 4
1865
1866=item *
1867
89853d76 1868C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1869
1870=item *
1871
1872The C<dtrace> build process has further changes:
1873
1874=over
1875
1876=item *
1877
1878If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1879built within a FreeBSD jail.
1880
1881=item *
1882
1883On systems that build a dtrace object file (FreeBSD, Solaris and
1884SystemTap's dtrace emulation), copy the input objects to a separate
1885directory and process them there, and use those objects in the link,
1886since C<dtrace -G> also modifies these objects.
1887
1888=item *
1889
1890Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1891to libelf symbols.
1892
1893=item *
1894
1895Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1896default build on Solaris generates probes from the unused inline
1897functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1898fail.
1899
1900=back
1901
1902[perl #130108]
1903
1904=item *
1905
1906You can now disable perl's use of the PERL_HASH_SEED and
1907PERL_PERTURB_KEYS environment variables by configuring perl with
1908C<-Accflags=NO_PERL_HASH_ENV>.
1909
1910=item *
1911
1912You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment
1913variable by configuring perl with
1914C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1915
1916=item *
1917
1918Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1919and C<Inf> to make builds more reproducible. [perl #130133]
1920
1921=item *
1922
1923Since 5.18 for testing purposes we have included support for
1924building perl with a variety of non-standard, and non-recommended
95b17558
KW
1925hash functions. Since we do not recommend the use of these functions
1926we have removed them and their corresponding build options. Specifically
2c8edc25
S
1927this includes the following build options:
1928
1929 PERL_HASH_FUNC_SDBM
1930 PERL_HASH_FUNC_DJB2
1931 PERL_HASH_FUNC_SUPERFAST
1932 PERL_HASH_FUNC_MURMUR3
1933 PERL_HASH_FUNC_ONE_AT_A_TIME
1934 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1935 PERL_HASH_FUNC_MURMUR_HASH_64A
1936 PERL_HASH_FUNC_MURMUR_HASH_64B
1937
1938=item *
1939
1940Remove "Warning: perl appears in your path"
1941
1942This install warning is more or less obsolete, since most platforms already
1943*will* have a /usr/bin/perl or similar provided by the OS.
1944
1945=item *
1946
1947Reduce verbosity of "make install.man"
1948
1949Previously, two progress messages were emitted for each manpage: one by
1950installman itself, and one by the function in install_lib.pl that it calls to
95b17558 1951actually install the file. Disabling the second of those in each case saves
2c8edc25
S
1952over 750 lines of unhelpful output.
1953
1954=item *
1955
1956Cleanup for clang -Weverything support. [perl 129961]
1957
1958=item *
1959
1960Configure: signbit scan was assuming too much, stop assuming negative 0.
1961
1962=item *
1963
1964Various compiler warnings have been silenced.
1965
1966=item *
1967
1968Several smaller changes have been made to remove impediments to compiling under
1969C++11.
1970
1971=item *
1972
1973Builds using C<USE_PAD_RESET> now work again; this configuration had
1974bit-rotted.
1975
1976=item *
1977
1978A probe for C<gai_strerror> was added to F<Configure> that checks if the
1979the gai_strerror() routine is available and can be used to
1980translate error codes returned by getaddrinfo() into human
1981readable strings.
1982
1983=item *
1984
1985F<Configure> now aborts if both "-Duselongdouble" and "-Dusequadmath" are
1986requested.
1987L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1988
1989=item *
1990
1991Fixed a bug in which F<Configure> could append "-quadmath" to the archname even
1992if it was already present.
1993L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1994
1995=item *
1996
1997Clang builds with "-DPERL_GLOBAL_STRUCT" or "-DPERL_GLOBAL_STRUCT_PRIVATE" have
1998been fixed (by disabling Thread Safety Analysis for these configurations).
1999
2000=item *
2001
2002F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
2003files require updates. This could cause dependencies, F<perlmain.c>
2004in particular, to be rebuilt unnecessarily. [perl #126710]
2005
2006=item *
2007
2008The output of C<perl -V> has been reformatted so that each configuration
2009and compile-time option is now listed one per line, to improve
2010readability.
2011
2012=item *
2013
2014C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
2015invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
2016This means you can supply your target platform C<config.sh>, generate
2017the headers and proceed to build your cross-target perl. [perl #127234]
2018
2019=item *
2020
2021Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
2022counts when the environment variable C<PERL_TRACE_OPS> to be set to a
2023non-zero integer. This allows C<make test> to pass on such a build.
2024
2025=item *
2026
2027When building with GCC 6 and link-time optimization (the C<-flto> option to
2028C<gcc>), C<Configure> was treating all probed symbols as present on the
95b17558 2029system, regardless of whether they actually exist. This has been fixed.
2c8edc25
S
2030[perl #128131]
2031
2032=item *
2033
2034The F<t/test.pl> library is used for internal testing of Perl itself, and
95b17558 2035also copied by several CPAN modules. Some of those modules must work on
2c8edc25 2036older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
95b17558 2037features. Compatibility with Perl 5.8 was inadvertently removed some time
2c8edc25
S
2038ago; it has now been restored. [perl #128052]
2039
2040=item *
2041
2042The build process no longer emits an extra blank line before building each
2043"simple" extension (those with only F<*.pm> and F<*.pod> files).
2044
2045=back
2046
2047=head1 Testing
2048
2049=over 4
2050
2051=item *
2052
2053F<XS-APItest/t/utf8.t>: Several small fixes and enhancements.
2054
2055=item *
2056
2057Tests for locales were erroneously using locales incompatible with Perl.
2058
2059=item *
2060
2061Some parts of the test suite that try to exhaustively test edge cases in the
2062regex implementation have been restricted to running for a maximum of five
95b17558 2063minutes. On slow systems they could otherwise take several hours, without
2c8edc25
S
2064significantly improving our understanding of the correctness of the code
2065under test.
2066
2067In addition, some of those test cases have been split into more files, to
2068allow them to be run in parallel on suitable systems.
2069
2070=item *
2071
2072A new internal facility allows analysing the time taken by the individual
2073tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
2074
2075=item *
2076
2077F<t/re/regexp_nonull.t> has been added to test that the regular expression
2078engine can handle scalars that do not have a null byte just past the end of
2079the string.
2080
2081=item *
2082
2083A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
2084"Declaring a reference to a variable".
2085
2086=item *
2087
2088A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
2089generated by bracketed character classes are as expected.
2090
2091=item *
2092
2093F<t/harness> now tries really hard not to run tests outside of the Perl
2094source tree. [perl #124050]
2095
2096=back
2097
2098=head1 Platform Support
2099
2100=head2 New Platforms
2101
2102=over 4
2103
2104=item NetBSD/VAX
2105
2106Perl now compiles under NetBSD on VAX machines. However, it's not
2107possible for that platform to implement floating-point infinities and
2108NaNs compatibly with most modern systems, which implement the IEEE-754
2109floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2110literals, C<printf %a>) is not implemented, either.
2111The C<make test> passes 98% of tests.
2112
2113=over 4
2114
2115=item *
2116
2117Test fixes and minor updates.
2118
2119=item *
2120
2121Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2122
2123=back
2124
2125=back
2126
2127=head2 Platform-Specific Notes
2128
2129=over 4
2130
2131=item Darwin
2132
2133don't treat -Dprefix=/usr as special, instead require an extra option
2134-Ddarwin_distribution to produce the same results.
2135
2136=item POSIX
2137
2138Finish removing POSIX deprecated functions.
2139
2140=item OS X
2141
29ce4d71 2142OS X El Capitan doesn't implement the clock_gettime() or clock_getres() APIs;
2c8edc25
S
2143emulate them as necessary.
2144
2145=item macOS
2146
2147Deprecated syscall(2) on macOS 10.12.
2148
2149=item EBCDIC
2150
2151Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2152
2153=item HP-UX
2154
2155L<Net::Ping> UDP test is skipped on HP-UX.
2156
2157=item Hurd
2158
2159The hints for Hurd have been improved enabling malloc wrap and reporting the
2160GNU libc used (previously it was an empty string when reported).
2161
2162=item VAX
2163
29ce4d71 2164VAX floating point formats are now supported on NetBSD.
2c8edc25
S
2165
2166=item VMS
2167
2168=over 4
2169
2170=item *
2171
2172The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
95b17558 2173now a colon (C<:>) when running under a Unix shell. There is no change when
2c8edc25
S
2174running under DCL (it's still C<|>).
2175
2176=item *
2177
29ce4d71
CB
2178C<configure.com> now recognizes the VSI-branded C compiler and no longer
2179recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
218015 or more years).
2c8edc25
S
2181
2182=back
2183
2184=item Windows
2185
2186=over 4
2187
2188=item *
2189
2190Support for compiling perl on Windows using Microsoft Visual Studio 2015
2191(containing Visual C++ 14.0) has been added.
2192
2193This version of VC++ includes a completely rewritten C run-time library, some
2194of the changes in which mean that work done to resolve a socket close() bug in
2195perl #120091 and perl #118059 is not workable in its current state with this
2196version of VC++. Therefore, we have effectively reverted that bug fix for
2197VS2015 onwards on the basis that being able to build with VS2015 onwards is
2198more important than keeping the bug fix. We may revisit this in the future to
2199attempt to fix the bug again in a way that is compatible with VS2015.
2200
2201These changes do not affect compilation with GCC or with Visual Studio versions
fce64130 2202up to and including VS2013, I<i.e.>, the bug fix is retained (unchanged) for those
2c8edc25
S
2203compilers.
2204
2205Note that you may experience compatibility problems if you mix a perl built
2206with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2207perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2208Some incompatibility may arise because of the bug fix that has been reverted
2209for VS2015 builds of perl, but there may well be incompatibility anyway because
fce64130 2210of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
2c8edc25
S
2211http://stackoverflow.com/questions/30412951).
2212
2213=back
2214
2215=item Win32
2216
2217=over 4
2218
2219=item *
2220
95b17558 2221Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2c8edc25 2222depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
95b17558 2223the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2c8edc25
S
2224
2225=item *
2226
2227fp definitions have been updated.
2228
2229=back
2230
2c8edc25
S
2231=item Linux
2232
2233Drop support for Linux a.out Linux has used ELF for over twenty years.
2234
2235=item OpenBSD 6
2236
2237OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2238Make sure this is accounted for.
2239
2240=item FreeBSD
2241
2242t/uni/overload.t: Skip hanging test on FreeBSD.
2243
2244=back
2245
2246=head1 Internal Changes
2247
2248=over 4
2249
2250=item *
2251
95b17558 2252The C<op_class()> API function has been added. This is like the existing
2c8edc25 2253C<OP_CLASS()> macro, but can more accurately determine what struct an op
95b17558 2254has been allocated as. For example C<OP_CLASS()> might return
2c8edc25
S
2255C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2256allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2257C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2258
2259=item *
2260
2261The output format of the C<op_dump()> function (as used by C<perl -Dx>)
2262has changed: it now displays an "ASCII-art" tree structure, and shows more
2263low-level details about each op, such as its address and class.
2264
2265=item *
2266
2267New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
2268been added, each with the
2269suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
2270parameter, giving an upper limit of how far into the string it is safe
2271to read. Using the old versions could cause attempts to read beyond the
2272end of the input buffer if the UTF-8 is not well-formed, and their use
2273now raises a deprecation warning. Details are at
2274L<perlapi/Character classification>.
2275
2276=item *
2277
2278Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
53799a91 2279deprecation warning since Perl 5.18. They now die.
2c8edc25
S
2280Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
2281
2282=item *
2283
2284Calling the functions C<utf8n_to_uvchr> and its derivatives, while
2285passing a string length of 0 is now asserted against in DEBUGGING
2286builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If
2287you have nothing to decode, you shouldn't call the decode function.
2288
2289=item *
2290
2291The functions C<utf8n_to_uvchr> and its derivatives now return the
2292Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong
2293malformation, and that malformation is allowed by the input parameters.
2294This malformation is where the UTF-8 looks valid syntactically, but
2295there is a shorter sequence that yields the same code point. This has
2296been forbidden since Unicode version 3.1.
2297
2298=item *
2299
2300The functions C<utf8n_to_uvchr> and its derivatives now accept an input
2301flag to allow the overflow malformation. This malformation is when the
2302UTF-8 may be syntactically valid, but the code point it represents is
2303not capable of being represented in the word length on the platform.
2304What "allowed" means in this case is that the function doesn't return an
2305error, and advances the parse pointer to beyond the UTF-8 in question,
2306but it returns the Unicode REPLACEMENT CHARACTER as the value of the
2307code point (since the real value is not representable).
2308
2309=item *
2310
2311The C<PADOFFSET> type has changed from being unsigned to signed, and
2312several pad-related variables such as C<PL_padix> have changed from being
2313of type C<I32> to type C<PADOFFSET>.
2314
2315=item *
2316
2317The function C<L<perlapi/utf8n_to_uvchr>> has been changed to not
2318abandon searching for other malformations when the first one is
2319encountered. A call to it thus can generate multiple diagnostics,
2320instead of just one.
2321
2322=item *
2323
2324A new function, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
2325use by modules that need to know the details of UTF-8 malformations
2326beyond pass/fail. Previously, the only ways to know why a sequence was
2327ill-formed was to capture and parse the generated diagnostics, or to do
2328your own analysis.
2329
2330=item *
2331
2332Several new functions for handling Unicode have been added to the API:
2333C<L<perlapi/is_strict_utf8_string>>,
2334C<L<perlapi/is_c9strict_utf8_string>>,
2335C<L<perlapi/is_utf8_string_flags>>,
2336C<L<perlapi/is_strict_utf8_string_loc>>,
2337C<L<perlapi/is_strict_utf8_string_loclen>>,
2338C<L<perlapi/is_c9strict_utf8_string_loc>>,
2339C<L<perlapi/is_c9strict_utf8_string_loclen>>,
2340C<L<perlapi/is_utf8_string_loc_flags>>,
2341C<L<perlapi/is_utf8_string_loclen_flags>>,
2342C<L<perlapi/is_utf8_fixed_width_buf_flags>>,
2343C<L<perlapi/is_utf8_fixed_width_buf_loc_flags>>,
2344C<L<perlapi/is_utf8_fixed_width_buf_loclen_flags>>.
2345
2346These functions are all extensions of the C<is_utf8_string_*()> functions,
2347that apply various restrictions to the UTF-8 recognized as valid.
2348
2349=item *
2350
2351A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
2352length and allocated size of the buffer in an C<SV>, growing the buffer if
2353necessary.
2354
2355=item *
2356
2357A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
2358like Perl-space C<$x = ''>, but with several optimisations.
2359
2360=item *
2361
2362All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2363previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2364that several parts of the internals had to be special-cased to accommodate
95b17558 2365it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2c8edc25
S
2366that is now handled in a simpler way.
2367
2368=item *
2369
2370Several new internal C macros have been added that take a string literal as
2371arguments, alongside existing routines that take the equivalent value as two
95b17558 2372arguments, a character pointer and a length. The advantage of this is that
2c8edc25 2373the length of the string is calculated automatically, rather than having to
95b17558 2374be done manually. These routines are now used where appropriate across the
2c8edc25
S
2375entire codebase.
2376
2377=item *
2378
2379The code in F<gv.c> that determines whether a variable has a special meaning
2380to Perl has been simplified.
2381
2382=item *
2383
2384The C<DEBUGGING>-mode output for regex compilation and execution has been
2385enhanced.
2386
2387=item *
2388
2389Several macros and functions have been added to the public API for
2390dealing with Unicode and UTF-8-encoded strings. See
2391L<perlapi/Unicode Support>.
2392
2393=item *
2394
95b17558 2395Use C<my_strlcat()> in C<locale.c>. While C<strcat()> is safe in this context,
2c8edc25 2396some compilers were optimizing this to C<strcpy()> causing a porting test to
95b17558 2397fail that looks for unsafe code. Rather than fighting this, we just use
2c8edc25
S
2398C<my_strlcat()> instead.
2399
2400=item *
2401
2402Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
95b17558 2403been added. These are intended principally to implement the individual
2c8edc25
S
2404elements of a subroutine signature, plus any overall checking required.
2405
2406=item *
2407
2408Perl no longer panics when switching into some locales on machines with
2409buggy C<strxfrm()> implementations in their libc. [perl #121734]
2410
2411=item *
2412
2413Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
95b17558 2414default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2c8edc25 2415This flag alters how the C<op_sibling> field is used in C<OP> structures,
53799a91 2416and has been available optionally since perl 5.22.
2c8edc25
S
2417
2418See L<perl5220delta/"Internal Changes"> for more details of what this
2419build option does.
2420
2421=item *
2422
2423The meanings of some internal SV flags have been changed
2424
2425OPpRUNTIME, SVpbm_VALID, SVpbm_TAIL, SvTAIL_on, SvTAIL_off, SVrepl_EVAL,
2426SvEVALED
2427
2428=item *
2429
2430Change C<hv_fetch(…, "…", …, …)> to C<hv_fetchs(…, "…", …)>
2431
2432The dual-life dists all use Devel::PPPort, so they can use this function even
2433though it was only added in 5.10.
2434
2435=back
2436
2437=head1 Selected Bug Fixes
2438
2439=over 4
2440
2441=item *
2442
2443C< $-{$name} > would leak an C<AV> on each access if the regular
2444expression had no named captures. The same applies to access to any
2445hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2446#130822]
2447
2448=item *
2449
2450Attempting to use the deprecated variable C<$#> as the object in an
2451indirect object method call could cause a heap use after free or
2452buffer overflow. [perl #129274]
2453
2454=item *
2455
2456When checking for an indirect object method call in some rare cases
2457the parser could reallocate the line buffer but then continue to use
2458pointers to the old buffer. [perl #129190]
2459
2460=item *
2461
2462Supplying a glob as the format argument to L<perlfunc/formline> would
2463cause an assertion failure. [perl #130722]
2464
2465=item *
2466
2467Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
2468converted into a qr// operator, leaving extra elements on the stack to
2469confuse any surrounding expression. [perl #130705]
2470
2471=item *
2472
53799a91 2473Since 5.24 in some obscure cases, a regex which included code blocks
fce64130 2474from multiple sources (I<e.g.>, via embedded via qr// objects) could end up
2c8edc25
S
2475with the wrong current pad and crash or give weird results. [perl #129881]
2476
2477=item *
2478
2479Occasionally C<local()>s in a code block within a patterns weren't being
2480undone when the pattern matching backtracked over the code block.
2481[perl #126697]
2482
2483=item *
2484
2485Using C<substr()> to modify a magic variable could access freed memory
2486in some cases. [perl #129340]
2487
2488=item *
2489
2c8edc25
S
2490Under C<use utf8>, the entire Perl program is now checked that the UTF-8
2491is wellformed. This resolves [perl #126310].
2492
2493=item *
2494
2495The range operator C<..> on strings now handles its arguments correctly when in
2496the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
95b17558 2497feature. The previous behaviour was sufficiently unexpected that we believe no
2c8edc25
S
2498correct program could have made use of it.
2499
2500=item *
2501
2502The S<split> operator did not ensure enough space was allocated for
2503its return value in scalar context. It could then write a single
2504pointer immediately beyond the end of the memory block allocated for
2505the stack. [perl #130262]
2506
2507=item *
2508
2509Using a large code point with the C<W> pack template character with
2510the current output position aligned at just the right point could
2511cause a write a single zero byte immediately beyond the end of an
2512allocated buffer. [perl #129149]
2513
2514=item *
2515
2516Supplying the form picture argument as part of the form argument list
2517where the picture specifies modifying the argument could cause an
2518access to the new freed compiled form. [perl #129125]
2519
2520=item *
2521
2522Fix a problem with sort's build-in compare, where it would not sort
2523correctly with 64-bit integers, and non-long doubles. [perl #130335]
2524
2525=item *
2526
2527Fix issues with /(?{ ... E<lt>E<lt>EOF })/ that broke Method-Signatures. [perl #130398]
2528
2529=item *
2530
2531Fix a macro which caused syntax error on an EBCDIC build.
2532
2533=item *
2534
2535Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2536
2537=item *
2538
2539Fixed an assertion failure with C<chop> and C<chomp>, which
2540could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2541
2542=item *
2543
2544Fixed a comment skipping error under C</x>; it could stop skipping a
2545byte early, which could be in the middle of a UTF-8 character.
2546[perl #130495].
2547
2548=item *
2549
2550F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2551
2552=item *
2553
2554Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2555
2556=item *
2557
2558DragonFly BSD now has support for setproctitle(). [perl #130068].
2559
2560=item *
2561
2562Fix an assertion error which could be triggered when lookahead string
2563in patterns exceeded a minimum length. [perl #130522].
2564
2565=item *
2566
2567Only warn once per literal about a misplaced C<_>. [perl #70878].
2568
2569=item *
2570
2571Ensure range-start is set after error in C<tr///>. [perl #129342].
2572
2573=item *
2574
2575Don't read past start of string for unmatched backref; otherwise,
2576we may have heap buffer overflow. [perl #129377].
2577
2578=item *
2579
2580Properly recognize mathematical digit ranges starting at U+1D7E.
2581C<use re 'strict'> is supposed to warn if you use a range whose start
95b17558 2582and end digit aren't from the same group of 10. It didn't do that
2c8edc25
S
2583for five groups of mathematical digits starting at U+1D7E.
2584
2585=item *
2586
fce64130 2587A sub containing a "forward" declaration with the same name (I<e.g.>,
2c8edc25
S
2588C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2589#129090]
2590
2591=item *
2592
2593A crash in executing a regex with a floating UTF-8 substring against a
2594target string that also used UTF-8 has been fixed. [perl #129350]
2595
2596=item *
2597
2598Previously, a shebang line like C<#!perl -i u> could be erroneously
95b17558 2599interpreted as requesting the C<-u> option. This has been fixed. [perl
2c8edc25
S
2600#129336]
2601
2602=item *
2603
2604The regex engine was previously producing incorrect results in some rare
2605situations when backtracking past a trie that matches only one thing; this
2606showed up as capture buffers (C<$1>, C<$2>, etc) erroneously containing data
2607from regex execution paths that weren't actually executed for the final
2608match. [perl #129897]
2609
2610=item *
2611
2612Certain regexes making use of the experimental C<regex_sets> feature could
95b17558 2613trigger an assertion failure. This has been fixed. [perl #129322]
2c8edc25
S
2614
2615=item *
2616
fce64130 2617Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
2c8edc25
S
2618sometimes crash in addition to giving a syntax error. [perl #125679]
2619
2620=item *
2621
2622The parser could sometimes crash if a bareword came after C<evalbytes>.
2623[perl #129196]
2624
2625=item *
2626
2627Autoloading via a method call would warn erroneously ("Use of inherited
2628AUTOLOAD for non-method") if there was a stub present in the package into
2629which the invocant had been blessed. The warning is no longer emitted in
2630such circumstances. [perl #47047]
2631
2632=item *
2633
fce64130
KW
2634A sub containing with a "forward" declaration with the same name
2635(I<e.g.>,
2c8edc25
S
2636C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2637#129090]
2638
2639=item *
2640
2641The use of C<splice> on arrays with nonexistent elements could cause other
2642operators to crash. [perl #129164]
2643
2644=item *
2645
2646Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2647string. [perl #129012]
2648
2649=item *
2650
2651Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2652checking that the I<current> C<cx> is the right type, and instead was always
2653checking the base C<cx> (effectively a noop). [perl #129029]
2654
2655=item *
2656
95b17558 2657Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2c8edc25
S
2658maintains up to two pointers into the parser buffer, one of which can
2659become stale under the right conditions. [perl #129069]
2660
2661=item *
2662
2663Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2664when it wasn't. [perl #129038]
2665
2666=item *
2667
2668Fixed place where regex was not setting the syntax error correctly.
2669[perl #129122]
2670
2671=item *
2672
2673The C<&.> operator (and the C<&> operator, when it treats its arguments as
2674strings) were failing to append a trailing null byte if at least one string
2675was marked as utf8 internally. Many code paths (system calls, regexp
2676compilation) still expect there to be a null byte in the string buffer
2677just past the end of the logical string. An assertion failure was the
2678result. [perl #129287]
2679
2680=item *
2681
2682Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2683silently truncates the supplied path if it won't fit into the C<sun_path>
95b17558 2684member of C<sockaddr_un>. This may change in the future, but for now
2c8edc25
S
2685check the path in theC<sockaddr> matches the desired path, and skip if
2686it doesn't. [perl #128095]
2687
2688=item *
2689
95b17558 2690Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2c8edc25
S
2691cases this is used in building error messages. [perl #128988]
2692
2693=item *
2694
2695Check for null PL_curcop in IN_LC() [perl #129106]
2696
2697=item *
2698
2699Fixed the parser error handling for an 'C<:attr(foo>' that does not have
2700an ending 'C<)>'.
2701
2702=item *
2703
2704Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2705actually fixed two bugs, [perl #129064] and [perl #129176].
2706
2707=item *
2708
2709[perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to
2710prevent possible string overrun with invalid len in gv.c
2711
2712=item *
2713
2714Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2715where the source and destination of the sort are the same plain array, are
95b17558 2716optimised to do less copying around. Two side-effects of this optimisation
2c8edc25
S
2717were that the contents of C<@a> as visible to to sort routine were
2718partially sorted, and under some circumstances accessing C<@a> during the
95b17558 2719sort could crash the interpreter. Both these issues have been fixed, and
2c8edc25
S
2720Sort functions see the original value of C<@a>.
2721
2722=item *
2723
2724Non-ASCII string delimiters are now reported correctly in error messages
2725for unterminated strings. [perl #128701]
2726
2727=item *
2728
2729C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2730temporary value") erroneously in some cases, but has been fixed.
2731
2732=item *
2733
2734C<@DB::args> is now exempt from "used once" warnings. The warnings only
2735occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2736multiple times.
2737
2738=item *
2739
2740The use of built-in arrays or hash slices in a double-quoted string no
2741longer issues a warning ("Possible unintended interpolation...") if the
2742variable has not been mentioned before. This affected code like
2743C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2744C<@-> and C<@+> were already exempt from the warning.)
2745
2746=item *
2747
2748C<gethostent> and similar functions now perform a null check internally, to
2749avoid crashing with torsocks. This was a regression from 5.22. [perl
2750#128740]
2751
2752=item *
2753
2754C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2755memory if the typeglob in question has never been accessed before.
2756
2757=item *
2758
2c8edc25
S
2759Mentioning the same constant twice in a row (which is a syntax error) no
2760longer fails an assertion under debugging builds. This was a regression
2761from 5.20. [perl #126482]
2762
2763=item *
2764
2765Many issues relating to C<printf "%a"> of hexadecimal floating point
2766were fixed. In addition, the "subnormals" (formerly known as "denormals")
2767floating point anumbers are now supported both with the plain IEEE 754
2768floating point numbers (64-bit or 128-bit) and the x86 80-bit
2769"extended precision". Note that subnormal hexadecimal floating
2770point literals will give a warning about "exponent underflow".
2771[perl #128843, #128889, #128890, #128893, #128909, #128919]
2772
2773=item *
2774
2775A regression in 5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2776128 and 255 has been fixed. [perl #128734].
2777
2778=item *
2779
2780A regression from the previous development release, 5.23.3, where
2781compiling a regular expression could crash the interpreter has been
2782fixed. [perl #128686].
2783
2784=item *
2785
2786Use of a string delimiter whose code point is above 2**31 now works
2787correctly on platforms that allow this. Previously, certain characters,
2788due to truncation, would be confused with other delimiter characters
2789with special meaning (such as C<?> in C<m?...?>), resulting
2790in inconsistent behaviour. Note that this is non-portable,
2791and is based on Perl's extension to UTF-8, and is probably not
2792displayable nor enterable by any editor. [perl #128738]
2793
2794=item *
2795
2796C<@{x> followed by a newline where C<x> represents a control or non-ASCII
2797character no longer produces a garbled syntax error message or a crash.
2798[perl #128951]
2799
2800=item *
2801
2802An assertion failure with C<%: = 0> has been fixed.
2803L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2804
2805=item *
2806
2807In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2808that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2809was to parse it as C<$foo:: . $bar>, has been restored.
2810L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2811
2812=item *
2813
2814Since Perl 5.20, line numbers have been off by one when perl is invoked with
2815the B<-x> switch. This has been fixed.
2816L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2817
2818=item *
2819
fce64130 2820Vivifying a subroutine stub in a deleted stash (I<e.g.>, C<delete $My::{"Foo::"};
2c8edc25
S
2821\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2822L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2823
2824=item *
2825
2826Some obscure cases of subroutines and file handles being freed at the same time
2827could result in crashes, but have been fixed. The crash was introduced in Perl
28285.22.
2829L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2830
2831=item *
2832
2833Code that looks for a variable name associated with an uninitialized value
2834could cause an assertion in cases where magic is involved, such as
2835C<$ISA[0][0]>. This has now been fixed.
2836L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2837
2838=item *
2839
2840A crash caused by code generating the warning "Subroutine STASH::NAME
2841redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2842fixed. In these cases, where the STASH is missing, the warning will now appear
2843as "Subroutine NAME redefined".
2844L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2845
2846=item *
2847
2848Fixed an assertion triggered by some code that handles deprecated behavior in
fce64130 2849formats, I<e.g.>, in cases like this:
2c8edc25
S
2850
2851 format STDOUT =
2852 @
2853 0"$x"
2854
2855L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2856
2857=item *
2858
2859A possible divide by zero in string transformation code on Windows has been
2860avoided, fixing a crash when collating an empty string.
2861L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2862
2863=item *
2864
2865Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2866regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2867L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2868
2869=item *
2870
2871C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2872warn when syntax warnings are enabled. [perl #127333]
2873
2874=item *
2875
2876socket() now leaves the error code returned by the system in C<$!> on
2877failure. [perl #128316]
2878
2879=item *
2880
2881Assignment variants of any bitwise ops under the C<bitwise> feature would
2882crash if the left-hand side was an array or hash. [perl #128204]
2883
2884=item *
2885
2886C<require> followed by a single colon (as in C<foo() ? require : ...> is
2887now parsed correctly as C<require> with implicit $_, rather than
2888C<require "">. [perl #128307]
2889
2890=item *
2891
2892Scalar C<keys %hash> can now be assigned to consistently in all scalar
2893lvalue contexts. Previously it worked for some contexts but not others.
2894
2895=item *
2896
2897List assignment to C<vec> or C<substr> with an array or hash for its first
2898argument used to result in crashes or "Can't coerce" error messages at run
2899time, unlike scalar assignment, which would give an error at compile time.
2900List assignment now gives a compile-time error, too. [perl #128260]
2901
2902=item *
2903
2904Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
95b17558 2905and C<or>) were being compiled incorrectly in some cases. If the left-hand
2c8edc25
S
2906side consisted of either a negated bareword constant or a negated C<do {}>
2907block containing a constant expression, and the right-hand side consisted of
2908a negated non-foldable expression, one of the negations was effectively
95b17558
KW
2909ignored. The same was true of C<if> and C<unless> statement modifiers,
2910though with the left-hand and right-hand sides swapped. This long-standing
2c8edc25
S
2911bug has now been fixed. [perl #127952]
2912
2913=item *
2914
2915C<reset> with an argument no longer crashes when encountering stash entries
2916other than globs. [perl #128106]
2917
2918=item *
2919
2920Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2921longer causes crashes. [perl #128086]
2922
2923=item *
2924
2925Handle SvIMMORTALs in LHS of list assign. [perl #129991]
2926
2927=item *
2928
2929[perl #130010] a5540cf breaks texinfo
2930
2931This involved user-defined Unicode properties.
2932
2933=item *
2934
2935Fix error message for unclosed C<\N{> in regcomp.
2936
2937An unclosed C<\N{> could give the wrong error message
2938C<"\N{NAME} must be resolved by the lexer">.
2939
2940=item *
2941
2942List assignment in list context where the LHS contained aggregates and
2943where there were not enough RHS elements, used to skip scalar lvalues.
2944Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
95b17558
KW
2945it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2946returns C<($a,$b,$c)>. This can be seen in the following:
2c8edc25
S
2947
2948 sub inc { $_++ for @_ }
2949 inc(($a,$b,@c,$d) = (10))
2950
2951Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2952now they are C<(11,1,1)>.
2953
2954=item *
2955
2956[perl 129903]
2957
2958The basic problem is that code like this: /(?{ s!!! })/ can trigger infinite
2959recursion on the C stack (not the normal perl stack) when the last successful
95b17558 2960pattern in scope is itself. Since the C stack overflows this manifests as an
2c8edc25
S
2961untrappable error/segfault, which then kills perl.
2962
2963We avoid the segfault by simply forbidding the use of the empty pattern when it
2964would resolve to the currently executing pattern.
2965
2966=item *
2967
2968[perl 128997] Avoid reading beyond the end of the line buffer when there's a
2969short UTF-8 character at the end.
2970
2971=item *
2972
2973[perl 129950] fix firstchar bitmap under utf8 with prefix optimisation.
2974
2975=item *
2976
2977[perl 129954] Carp/t/arg_string.t: be liberal in f/p formats.
2978
2979=item *
2980
2981[perl 129928] make do "a\0b" fail silently instead of throwing.
2982
2983=item *
2984
2985[perl 129130] make chdir allocate the stack it needs.
2986
2987=back
2988
2989=head1 Known Problems
2990
2991=over 4
2992
2993=item *
2994
2995Some modules have been broken by the L<context stack rework|/Internal Changes>.
2996These modules were relying on non-guaranteed implementation details in perl.
2997Their maintainers have been informed, and should contact perl5-porters for
2998advice if needed. Below is a subset of these modules:
2999
3000=over 4
3001
3002=item * L<Algorithm::Permute>
3003
3004=item * L<Coro>
3005
53799a91 3006L<Coro> and perl 5.22 were already incompatible due to a change in the perl,
2c8edc25
S
3007and the reworking on the perl context stack creates a further incompatibility.
3008perl5-porters has L<discussed the issue on the mailing
3009list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
3010
3011=item * L<Data::Alias>
3012
3013=item * L<RPerl>
3014
3015=item * L<Scope::Upper>
3016
3017=item * L<TryCatch>
3018
3019=back
3020
3021=item *
3022
53799a91 3023The module L<lexical::underscore> no longer works on Perl 5.24, because perl
2c8edc25
S
3024no longer has a lexical C<$_>!
3025
3026=item *
3027
53799a91 3028C<mod_perl> has been patched for compatibility for v5.22 and later but no
2c8edc25
S
3029release has been made. The relevant patch (and other changes) can be found in
3030their source code repository, L<mirrored at
3031GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
3032
3033=back
3034
3035=head1 Errata From Previous Releases
3036
3037=over 4
3038
3039=item *
3040
ee8180b8 3041Parsing bad POSIX charclasses no longer leaks memory.
2c8edc25
S
3042L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
3043
3044=item *
3045
53799a91 3046Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
2c8edc25
S
3047L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
3048
3049=back
3050
3051=head1 Obituary
3052
3053Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
95b17558 3054member, has passed away on August 10, 2016. He will be remembered and
c94c0e4f 3055missed by all those who he came in contact with, and enriched with his
2c8edc25
S
3056intellect, wit, and spirit.
3057
c94c0e4f 3058It is with great sadness that we also note Kip Hampton's passing. Probably
2c8edc25
S
3059best known as the author of the Perl & XML column on XML.com, he was a
3060core contributor to AxKit, an XML server platform that became an Apache
95b17558
KW
3061Foundation project. He was a frequent speaker in the early days at
3062OSCON, and most recently at YAPC::NA in Madison. He was frequently on
2c8edc25
S
3063irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
3064group responsible for YAPC::NA Asheville in 2011.
a049258c 3065
2c8edc25
S
3066Kip and his constant contributions to the community will be greatly
3067missed.
a049258c
S
3068
3069=head1 Acknowledgements
2e0dcc12 3070
0cc8c746 3071Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 3072and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
S
3073authors.
3074
3075Excluding auto-generated files, documentation and release tools, there were
3076approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
3077
3078Perl continues to flourish into its third decade thanks to a vibrant community
95b17558 3079of users and developers. The following people are known to have contributed the
ad543fb2 3080improvements that became Perl 5.26.0:
0cc8c746
S
3081
3082Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
3083König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
3084Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
3085Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
3086Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
3087Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3088Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3089Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3090D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3091Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3092De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3093Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3094Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3095Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3096Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3097Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3098Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3099Yves Orton, Zefram.
0cc8c746
S
3100
3101The list above is almost certainly incomplete as it is automatically generated
95b17558 3102from version control history. In particular, it does not include the names of
0cc8c746
S
3103the (very much appreciated) contributors who reported issues to the Perl bug
3104tracker.
3105
3106Many of the changes included in this version originated in the CPAN modules
95b17558 3107included in Perl's core. We're grateful to the entire CPAN community for
0cc8c746
S
3108helping Perl to flourish.
3109
3110For a more complete list of all of Perl's historical contributors, please see
3111the F<AUTHORS> file in the Perl source distribution.
f5b73711 3112
44691e6f
AB
3113=head1 Reporting Bugs
3114
2c8edc25
S
3115If you find what you think is a bug, you might check the articles recently
3116posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3117L<https://rt.perl.org/> . There may also be information at
4b8803f0 3118L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3119
e08634c5
SH
3120If you believe you have an unreported bug, please run the L<perlbug> program
3121included with your release. Be sure to trim your bug down to a tiny but
3122sufficient test case. Your bug report, along with the output of C<perl -V>,
3123will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
44691e6f 3124
87c118b9
DM
3125If the bug you are reporting has security implications which make it
3126inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3127L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3128for details of how to report the issue.
44691e6f
AB
3129
3130=head1 SEE ALSO
3131
e08634c5
SH
3132The F<Changes> file for an explanation of how to view exhaustive details on
3133what changed.
44691e6f
AB
3134
3135The F<INSTALL> file for how to build Perl.
3136
3137The F<README> file for general stuff.
3138
3139The F<Artistic> and F<Copying> files for copyright information.
3140
3141=cut