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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
df48f9a4 18=item * C<"."> no longer in C<@INC>
89853d76 19
df48f9a4 20For security reasons, the current directory (C<".">) is no longer included
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21by default at the end of the module search path (C<@INC>). This may have
22widespread implications for the building, testing and installing of
23modules, and for the execution of scripts. See the section
48e85ff2 24L<< Removal of the current directory (C<".">) from C<@INC> >>
8ab76fe6 25for the full details.
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26
27=item * C<do> may now warn
28
8928e7db 29C<do> now gives a deprecation warning when it fails to load a file which
df48f9a4 30it would have loaded had C<"."> been in C<@INC>.
89853d76 31
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32=item * In regular expression patterns, a literal left brace C<"{">
33should be escaped
34
35See L</Unescaped literal C<"{"> characters in regular expression patterns are no longer permissible>.
36
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37=back
38
2c8edc25 39=head1 Core Enhancements
f3ed8cbf 40
22a7b456 41=head2 Lexical subroutines are no longer experimental
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43Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
44code that disables the C<experimental::lexical_subs> warning category
45that the feature previously used will continue to work. The
46C<lexical_subs> feature has no effect; all Perl code can use lexical
47subroutines, regardless of what feature declarations are in scope.
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48
49=head2 Indented Here-documents
50
df48f9a4 51This adds a new modifier C<"~"> to here-docs that tells the parser
0f032fe1 52that it should look for C</^\s*$DELIM\n/> as the closing delimiter.
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53
54These syntaxes are all supported:
55
56 <<~EOF;
57 <<~\EOF;
58 <<~'EOF';
59 <<~"EOF";
60 <<~`EOF`;
61 <<~ 'EOF';
62 <<~ "EOF";
63 <<~ `EOF`;
64
df48f9a4 65The C<"~"> modifier will strip, from each line in the here-doc, the
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66same whitespace that appears before the delimiter.
67
fce64130 68Newlines will be copied as-is, and lines that don't include the
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69proper beginning whitespace will cause perl to croak.
70
71For example:
72
73 if (1) {
74 print <<~EOF;
75 Hello there
76 EOF
77 }
78
79prints "Hello there\n" with no leading whitespace.
80
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81=head2 New regular expression modifier C</xx>
82
df48f9a4 83Specifying two C<"x"> characters to modify a regular expression pattern
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84does everything that a single one does, but additionally TAB and SPACE
85characters within a bracketed character class are generally ignored and
86can be added to improve readability, like
87S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
88L<perlre/E<sol>x and E<sol>xx>.
89
0f032fe1 90=head2 C<@{^CAPTURE}>, C<%{^CAPTURE}>, and C<%{^CAPTURE_ALL}>
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91
92C<@{^CAPTURE}> exposes the capture buffers of the last match as an
95b17558 93array. So C<$1> is C<${^CAPTURE}[0]>. This is a more efficient equivalent
95013431 94to code like C<substr($matched_string,$-[0],$+[0]-$-[0])>, and you don't
95b17558 95have to keep track of the C<$matched_string> either. This variable has no
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96single character equivalent. Note that, like the other regex magic variables,
97the contents of this variable is dynamic; if you wish to store it beyond
95013431 98the lifetime of the match you must copy it to another array.
2c8edc25 99
fb5d4b1a 100C<%{^CAPTURE}> is equivalent to C<%+> (I<i.e.>, named captures). Other than
95013431 101being more self documenting there is no difference between the two forms.
2c8edc25 102
fb5d4b1a 103C<%{^CAPTURE_ALL}> is equivalent to C<%-> (I<i.e.>, all named captures).
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104Other than being more self documenting there is no difference between the
105two forms.
2c8edc25 106
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107=head2 Declaring a reference to a variable
108
109As an experimental feature, Perl now allows the referencing operator to come
110after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
111L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
112be enabled with C<use feature 'declared_refs'>. It is experimental, and will
113warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
114It is intended mainly for use in assignments to references. For example:
115
116 use experimental 'refaliasing', 'declared_refs';
117 my \$a = \$b;
118
119See L<perlref/Assigning to References> for more details.
120
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121=head2 Unicode 9.0 is now supported
122
123A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
124Modules that are shipped with core Perl but not maintained by p5p do not
125necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
126
127=head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
128
129Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and
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130called it Script_Extensions (C<scx>). Perl now uses this improved
131version when a property is specified as just C<\p{I<script>}>. This
132should make programs be more accurate when determining if a character is
133used in a given script, but there is a slight chance of breakage for
134programs that very specifically needed the old behavior. The meaning of
135compound forms, like C<\p{sc=I<script>}> are unchanged. See
136L<perlunicode/Scripts>.
2c8edc25 137
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138=head2 Perl can now do default collation in UTF-8 locales on platforms
139that support it
a049258c 140
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141Some platforms natively do a reasonable job of collating and sorting in
142UTF-8 locales. Perl now works with those. For portability and full
143control, L<Unicode::Collate> is still recommended, but now you may
144not need to do anything special to get good-enough results, depending on
145your application. See
146L<perllocale/Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>.
147
148=head2 Better locale collation of strings containing embedded C<NUL>
149characters
150
fce64130 151In locales that have multi-level character weights, C<NUL>s are now
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152ignored at the higher priority ones. There are still some gotchas in
153some strings, though. See
154L<perllocale/Collation of strings containing embedded C<NUL> characters>.
155
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156=head2 C<CORE> subroutines for hash and array functions callable via
157reference
158
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159The hash and array functions in the C<CORE> namespace (C<keys>, C<each>,
160C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>) can now
2c8edc25 161be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference
e6abae1c 162(C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be
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163used when inlined.
164
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165=head2 New Hash Function For 64-bit Builds
166
167We have switched to a hybrid hash function to better balance
168performance for short and long keys.
169
170For short keys, 16 bytes and under, we use an optimised variant of
171One At A Time Hard, and for longer keys we use Siphash 1-3. For very
172long keys this is a big improvement in performance. For shorter keys
173there is a modest improvement.
174
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175=head1 Security
176
df48f9a4 177=head2 Removal of the current directory (C<".">) from C<@INC>
2c8edc25 178
95b17558 179The perl binary includes a default set of paths in C<@INC>. Historically
df48f9a4 180it has also included the current directory (C<".">) as the final entry,
95b17558 181unless run with taint mode enabled (C<perl -T>). While convenient, this has
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182security implications: for example, where a script attempts to load an
183optional module when its current directory is untrusted (such as F</tmp>),
184it could load and execute code from under that directory.
185
df48f9a4 186Starting with v5.26, C<"."> is always removed by default, not just under
95b17558 187tainting. This has major implications for installing modules and executing
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188scripts.
189
190The following new features have been added to help ameliorate these
191issues.
192
193=over
194
195=item * C<Configure -Udefault_inc_excludes_dot>
196
197There is a new C<Configure> option, C<default_inc_excludes_dot> (enabled
df48f9a4 198by default) which builds a perl executable without C<".">; unsetting this
95b17558 199option using C<-U> reverts perl to the old behaviour. This may fix your
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200path issues but will reintroduce all the security concerns, so don't
201build a perl executable like this unless you're I<really> confident that
202such issues are not a concern in your environment.
203
409c12ef 204=item * C<PERL_USE_UNSAFE_INC>
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205
206There is a new environment variable recognised by the perl interpreter.
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207If this variable has the value 1 when the perl interpreter starts up,
208then C<"."> will be automatically appended to C<@INC> (except under tainting).
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209
210This allows you restore the old perl interpreter behaviour on a
95b17558 211case-by-case basis. But note that this is intended to be a temporary crutch,
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212and this feature will likely be removed in some future perl version.
213It is currently set by the C<cpan> utility and C<Test::Harness> to
fce64130 214ease installation of CPAN modules which have not been updated to handle the
95b17558 215lack of dot. Once again, don't use this unless you are sure that this
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216will not reintroduce any security concerns.
217
218=item * A new mandatory warning issued by C<do>.
219
220While it is well-known that C<use> and C<require> use C<@INC> to search
221for the file to load, many people don't realise that C<do "file"> also
df48f9a4 222searches C<@INC> if the file is a relative path. With the removal of C<".">,
89853d76 223a simple C<do "file.pl"> will fail to read in and execute C<file.pl> from
95b17558 224the current directory. Since this is commonly expected behaviour, a new
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225mandatory warning is now issued whenever C<do> fails to load a file which
226it otherwise would have found if dot had been in C<@INC>.
227
228=back
229
230Here are some things script and module authors may need to do to make
231their software work in the new regime.
232
233=over
234
235=item * Script authors
236
237If the issue is within your own code (rather than within included
95b17558 238modules), then you have two main options. Firstly, if you are confident
89853d76 239that your script will only be run within a trusted directory (under which
df48f9a4 240you expect to find trusted files and modules), then add C<"."> back into the
fce64130 241path; I<e.g.>:
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242
243 BEGIN {
244 my $dir = "/some/trusted/directory";
245 chdir $dir or die "Can't chdir to $dir: $!\n";
246 # safe now
247 push @INC, '.';
248 }
249 use "Foo::Bar"; # may load /some/trusted/directory/Foo/Bar.pm
250 do "config.pl"; # may load /some/trusted/directory/config.pl
251
252On the other hand, if your script is intended to be run from within
253untrusted directories (such as F</tmp>), then your script suddenly failing
95b17558 254to load files may be indicative of a security issue. You most likely want
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255to replace any relative paths with full paths; for example,
256
257 do ".foo_config.pl"
258
259might become
260
261 do "$ENV{HOME}/.foo_config.pl"
262
263If you are absolutely certain that you want your script to load and
264execute a file from the current directory, then use a C<./> prefix; for
265example:
266
267 do "./.foo_config.pl"
268
269=item * Installing and using CPAN modules
270
271If you install a CPAN module using an automatic tool like C<cpan>, then
272this tool will itself set the C<PERL_USE_UNSAFE_INC> environment variable
273while building and testing the module, which may be sufficient to install
274a distribution which hasn't been updated to be dot-aware. If you want to
275install such a module manually, then you'll need to replace the
276traditional invocation:
277
278 perl Makefile.PL && make && make test && make install
279
280with something like
281
282 (export PERL_USE_UNSAFE_INC=1; \
283 perl Makefile.PL && make && make test && make install)
284
95b17558 285Note that this only helps build and install an unfixed module. It's
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286possible for the tests to pass (since they were run under
287C<PERL_USE_UNSAFE_INC=1>), but for the module itself to fail to perform
95b17558 288correctly in production. In this case you may have to temporarily modify
0f275d26 289your script until such time as a fixed version of the module is released.
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290For example:
291
292 use Foo::Bar;
293 {
294 local @INC = (@INC, '.');
295 # assuming read_config() needs '.' in @INC
296 $config = Foo::Bar->read_config();
297 }
298
95b17558 299This is only rarely expected to be necessary. Again, if doing this,
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300assess the resultant risks first.
301
302=item * Module Authors
303
304If you maintain a CPAN distribution, it may need updating to run in
95b17558 305a dotless environment. Although C<cpan> and other such tools will
0f275d26 306currently set the C<PERL_USE_UNSAFE_INC> during module build, this is a
df48f9a4 307temporary workaround for the set of modules which rely on C<"."> being in
95b17558 308C<@INC> for installation and testing, and this may mask deeper issues. It
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309could result in a module which passes tests and installs, but which
310fails at run time.
311
312During build, test and install, it will normally be the case that any perl
313processes will be executing directly within the root directory of the
95b17558 314untarred distribution, or a known subdirectory of that, such as F<t/>. It
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315may well be that F<Makefile.PL> or F<t/foo.t> will attempt to include
316local modules and configuration files using their direct relative
317filenames, which will now fail.
318
319However, as described above, automatic tools like F<cpan> will (for now)
320set the C<PERL_USE_UNSAFE_INC> environment variable, which introduces
321dot during build.
322
323This makes it likely that your existing build and test code will work, but
324this may mask issues with your code which only manifest when used after
95b17558 325install. It is prudent to try and run your build process with that
89853d76 326variable explicitly disabled:
0f275d26 327
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328 (export PERL_USE_UNSAFE_INC=0; \
329 perl Makefile.PL && make && make test && make install)
330
331This is more likely to show up any potential problems with your module's
95b17558 332build process, or even with the module itself. Fixing such issues will
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333ensure both that your module can again be installed manually, and that
334it will still build once the C<PERL_USE_UNSAFE_INC> crutch goes away.
335
336When fixing issues in tests due to the removal of dot from C<@INC>,
337reinsertion of dot into C<@INC> should be performed with caution, for this
95b17558 338too may suppress real errors in your runtime code. You are encouraged
89853d76 339wherever possible to apply the aforementioned approaches with explicit
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340absolute/relative paths, or to relocate your needed files into a
341subdirectory and insert that subdirectory into C<@INC> instead.
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342
343If your runtime code has problems under the dotless C<@INC>, then the comments
95b17558 344above on how to fix for script authors will mostly apply here too. Bear in
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345mind though that it is considered bad form for a module to globally add dot to
346C<@INC>, since it introduces both a security risk and hides issues of
347accidentally requiring dot in C<@INC>, as explained above.
348
349=back
2c8edc25 350
fb5d4b1a 351=head2 Escaped colons and relative paths in PATH
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352
353On Unix systems, Perl treats any relative paths in the PATH environment
354variable as tainted when starting a new process. Previously, it was
355allowing a backslash to escape a colon (unlike the OS), consequently
356allowing relative paths to be considered safe if the PATH was set to
5aeff080 357something like C</\:.>. The check has been fixed to treat C<"."> as tainted
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358in that example.
359
360=head2 C<-Di> switch is now required for PerlIO debugging output
361
362Previously PerlIO debugging output would be sent to the file specified
363by the C<PERLIO_DEBUG> environment variable if perl wasn't running
364setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
365
366If perl performed output at a point where it hadn't yet parsed its
367switches this could result in perl creating or overwriting the file
368named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
369
370Perl now requires the C<-Di> switch to produce PerlIO debugging
371output. By default this is written to C<stderr>, but can optionally
372be redirected to a file by setting the C<PERLIO_DEBUG> environment
373variable.
a049258c 374
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375If perl is running setuid or the C<-T> switch has supplied
376C<PERLIO_DEBUG> is ignored and the debugging output is sent to
377C<stderr> as for any other C<-D> switch.
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378
379=head1 Incompatible Changes
380
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381=head2 Unescaped literal C<"{"> characters in regular expression
382patterns are no longer permissible
a049258c 383
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384You have to now say something like C<"\{"> or C<"[{]"> to specify to
385match a LEFT CURLY BRACKET; otherwise it is a fatal pattern compilation
386error. This change will allow future extensions to the language.
387
388These have been deprecated since v5.16, with a deprecation message
389raised for some uses starting in v5.22. Unfortunately, the code added
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390to raise the message was buggy, and failed to warn in some cases where
391it should have. Therefore, enforcement of this ban for these cases is
392deferred until Perl 5.30, but the code has been fixed to raise a
393default-on deprecation message for them in the meantime.
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394
395Some uses of literal C<"{"> occur in contexts where we do not foresee
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396the meaning ever being anything but the literal, such as the very first
397character in the pattern, or after a C<"|"> meaning alternation. Thus
398
399 qr/{fee|{fie/
400
401matches either of the strings C<{fee> or C<{fie>. To avoid forcing
402unnecessary code changes, these uses do not need to be escaped, and no
403warning is raised about them, and there are no current plans to change this.
404
405But it is always correct to escape C<"{">, and the simple rule to
406remember is to always do so.
a049258c 407
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408=head2 C<scalar(%hash)> return signature changed
409
410The value returned for C<scalar(%hash)> will no longer show information about
411the buckets allocated in the hash. It will simply return the count of used
412keys. It is thus equivalent to C<0+keys(%hash)>.
413
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414A form of backwards compatibility is provided via
415L<C<Hash::Util::bucket_ratio()>|Hash::Util/bucket_ratio> which provides
416the same behavior as
417C<scalar(%hash)> provided in Perl 5.24 and earlier.
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418
419=head2 C<keys> returned from an lvalue subroutine
420
421C<keys> returned from an lvalue subroutine can no longer be assigned
422to in list context.
423
424 sub foo : lvalue { keys(%INC) }
425 (foo) = 3; # death
426 sub bar : lvalue { keys(@_) }
427 (bar) = 3; # also an error
428
429This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
430C<(keys @_) = ...>, which are also errors. [perl #128187]
a049258c 431
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432=head2 C<${^ENCODING}> has been removed
433
434Consequently, the L<encoding> pragma's default mode is no longer supported. If
435you still need to write your source code in encodings other than UTF-8, use a
436source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
437option.
438
0f032fe1 439=head2 C<POSIX::tmpnam()> has been removed
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440
441The fundamentally unsafe C<tmpnam()> interface was deprecated in
53799a91 442Perl 5.22 and has now been removed. In its place you can use,
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443for example, the L<File::Temp> interfaces.
444
445=head2 require ::Foo::Bar is now illegal.
446
95b17558 447Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
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448bareword require which starts with a double colon dies instead.
449
450=head2 Literal control character variable names are no longer permissible
451
452A variable name may no longer contain a literal control character under
453any circumstances. These previously were allowed in single-character
454names on ASCII platforms, but have been deprecated there since Perl
4555.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
456control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
457source code.
458
459=head2 C<NBSP> is no longer permissible in C<\N{...}>
460
461The name of a character may no longer contain non-breaking spaces. It
53799a91 462has been deprecated to do so since Perl 5.22.
8d25d2f3 463
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464=head1 Deprecations
465
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466=head2 String delimiters that aren't stand-alone graphemes are now deprecated
467
468In order for Perl to eventually allow string delimiters to be Unicode
469grapheme clusters (which look like a single character, but may be
0f275d26 470a sequence of several ones), we have to stop allowing a single character
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471delimiter that isn't a grapheme by itself. These are unlikely to exist
472in actual code, as they would typically display as attached to the
473character in front of them.
474
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475=head2 C<\cI<X>> that maps to a printable is no longer deprecated
476
477This means we have no plans to remove this feature. It still raises a
478warning, but only if syntax warnings are enabled. The feature was
479originally intended to be a way to express non-printable characters that
480don't have a mnemonic (C<\t> and C<\n> are mnemonics for two
481non-printable characters, but most non-printables don't have a
482mnemonic.) But the feature can be used to specify a few printable
483characters, though those are more clearly expressed as the printable
484itself. See
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485L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>.
486
2c8edc25 487=head1 Performance Enhancements
a049258c 488
2c8edc25 489=over 4
a049258c 490
2c8edc25 491=item *
a049258c 492
fce64130 493A hash in boolean context is now sometimes faster, I<e.g.>
a049258c 494
2c8edc25 495 if (!%h) { ... }
a049258c 496
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497This was already special-cased, but some cases were missed (such as
498C<grep %$_, @AoH>, and even the ones which weren't have been improved.
a049258c 499
2c8edc25 500=item * New Faster Hash Function on 64 bit builds
a049258c 501
95b17558 502We use a different hash function for short and long keys. This should
2c8edc25 503improve performance and security, especially for long keys.
a049258c 504
2c8edc25 505=item * readline is faster
a049258c 506
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507Reading from a file line-by-line with C<readline()> or C<< E<lt>E<gt> >> should
508now typically be faster due to a better implementation of the code that
509searches for the next newline character.
510
511=item *
a049258c 512
0f032fe1 513Reduce cost of C<SvVALID()>.
a049258c 514
2c8edc25 515=item *
ad5c8857 516
2c8edc25 517C<$ref1 = $ref2> has been optimized.
5e50eae4 518
4b99a68c 519=item *
f4b40f11 520
fce64130 521Array and hash assignment are now faster, I<e.g.>
ec34c8a4 522
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523 (..., @a) = (...);
524 (..., %h) = (...);
f4b40f11 525
2c8edc25 526especially when the RHS is empty.
ec34c8a4 527
2c8edc25 528=item *
a049258c 529
2c8edc25 530Reduce the number of odd special cases for the C<SvSCREAM> flag.
e770df11 531
2c8edc25 532=item *
a049258c 533
0f032fe1 534Avoid C<sv_catpvn()> in C<do_vop()> when unneeded.
2c8edc25
S
535
536=item *
537
538Enhancements in Regex concat COW implementation.
539
540=item *
541
8928e7db
DM
542Better optimise array and hash assignment: where an array or hash appears
543in the LHS of a list assignment, such as C<(..., @a) = (...);>, it's
544likely to be considerably faster, especially if it involves emptying the
545array/hash. For example this code runs about 1/3 faster compared to
d3972b39 546Perl 5.24.0:
d053832c
AB
547
548 my @a;
8928e7db 549 for my $i (1..10_000_000) {
d053832c
AB
550 @a = (1,2,3);
551 @a = ();
552 }
553
2c8edc25
S
554
555=item *
556
557Converting a single-digit string to a number is now substantially faster.
558
559=item *
560
561The internal op implementing the C<split> builtin has been simplified and
95b17558
KW
562sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
563to do its work. Secondly, code of the form C<my @x = split(...)> is now
2c8edc25
S
564optimised in the same way as C<@x = split(...)>, and is therefore a few
565percent faster.
566
567=item *
568
569The rather slow implementation for the experimental subroutine signatures
570feature has been made much faster; it is now comparable in speed with the
571old-style C<my ($a, $b, @c) = @_>.
7ca0bfc4 572
fbe3f407
S
573=item *
574
2c8edc25 575Bareword constant strings are now permitted to take part in constant
95b17558 576folding. They were originally exempted from constant folding in August 1999,
2c8edc25 577during the development of Perl 5.6, to ensure that C<use strict "subs">
95b17558 578would still apply to bareword constants. That has now been accomplished a
2c8edc25
S
579different way, so barewords, like other constants, now gain the performance
580benefits of constant folding.
581
582This also means that void-context warnings on constant expressions of
583barewords now report the folded constant operand, rather than the operation;
584this matches the behaviour for non-bareword constants.
a049258c
S
585
586=back
587
2c8edc25
S
588=head1 Modules and Pragmata
589
a049258c
S
590=head2 Updated Modules and Pragmata
591
592=over 4
fbe3f407 593
759020c9 594=item *
7ca0bfc4 595
0cc8c746
S
596L<Archive::Tar> has been upgraded from version 2.04 to 2.24.
597
598=item *
599
600L<arybase> has been upgraded from version 0.11 to 0.12.
601
602=item *
603
604L<attributes> has been upgraded from version 0.27 to 0.29.
a049258c 605
2c8edc25 606The deprecation message for the C<:unique> and C<:locked> attributes
0f275d26 607now mention that they will disappear in Perl 5.28.
a049258c 608
2c8edc25 609=item *
a049258c 610
0cc8c746
S
611L<B> has been upgraded from version 1.62 to 1.68.
612
613=item *
614
615L<B::Concise> has been upgraded from version 0.996 to 0.999.
2c8edc25
S
616
617Its output is now more descriptive for C<op_private> flags.
d5c7a4fc 618
759020c9
S
619=item *
620
0cc8c746
S
621L<B::Debug> has been upgraded from version 1.23 to 1.24.
622
623=item *
624
625L<B::Deparse> has been upgraded from version 1.37 to 1.40.
626
627=item *
628
2c8edc25 629L<B::Xref> has been upgraded from version 1.05 to 1.06.
a049258c 630
2c8edc25 631It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 632
2c8edc25 633=item *
a049258c 634
0cc8c746
S
635L<base> has been upgraded from version 2.23 to 2.25.
636
637=item *
638
639L<bignum> has been upgraded from version 0.42 to 0.47.
640
641=item *
642
643L<Carp> has been upgraded from version 1.40 to 1.42.
644
645=item *
646
647L<charnames> has been upgraded from version 1.43 to 1.44.
648
649=item *
650
651L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.074.
652
653=item *
654
655L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.074.
656
657=item *
658
659L<Config::Perl::V> has been upgraded from version 0.25 to 0.28.
660
661=item *
662
663L<CPAN> has been upgraded from version 2.11 to 2.18.
664
665=item *
666
667L<CPAN::Meta> has been upgraded from version 2.150005 to 2.150010.
668
669=item *
670
671L<Data::Dumper> has been upgraded from version 2.160 to 2.167.
a049258c 672
2c8edc25 673The XS implementation now supports Deparse.
a049258c 674
2c8edc25 675This fixes a stack management bug. [perl #130487].
a049258c 676
2c8edc25 677=item *
a049258c 678
0cc8c746
S
679L<DB_File> has been upgraded from version 1.835 to 1.840.
680
681=item *
682
683L<Devel::Peek> has been upgraded from version 1.23 to 1.26.
684
685=item *
686
687L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
688
689=item *
690
2c8edc25 691L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
a049258c 692
2c8edc25 693It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 694
2c8edc25 695=item *
a049258c 696
0cc8c746 697L<diagnostics> has been upgraded from version 1.34 to 1.36.
a049258c 698
2c8edc25 699It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
7ca0bfc4 700
ad5c8857 701=item *
7ca0bfc4 702
0cc8c746
S
703L<Digest> has been upgraded from version 1.17 to 1.17_01.
704
705=item *
706
707L<Digest::MD5> has been upgraded from version 2.54 to 2.55.
708
709=item *
710
711L<Digest::SHA> has been upgraded from version 5.95 to 5.96.
712
713=item *
714
715L<DynaLoader> has been upgraded from version 1.38 to 1.42.
716
717=item *
718
719L<Encode> has been upgraded from version 2.80 to 2.88.
720
721=item *
722
723L<encoding> has been upgraded from version 2.17 to 2.19.
8f7edc68 724
ee8180b8 725This module's default mode is no longer supported. It now
2c8edc25 726dies when imported, unless the C<Filter> option is being used.
d5c7a4fc 727
2c8edc25 728=item *
d5c7a4fc 729
2c8edc25 730L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
a049258c 731
ee8180b8 732This module is no longer supported. It emits a warning to
2c8edc25 733that effect and then does nothing.
a049258c 734
2c8edc25 735=item *
d5c7a4fc 736
0cc8c746 737L<Errno> has been upgraded from version 1.25 to 1.28.
a049258c 738
2c8edc25 739Document that using C<%!> loads Errno for you.
d5c7a4fc 740
2c8edc25 741It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
3abe9611 742
c714fb1f 743=item *
3ce6a296 744
2c8edc25 745L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
a049258c 746
2c8edc25 747It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 748
2c8edc25 749=item *
a049258c 750
0cc8c746
S
751L<ExtUtils::MakeMaker> has been upgraded from version 7.10_01 to 7.24.
752
753=item *
754
755L<ExtUtils::Miniperl> has been upgraded from version 1.05 to 1.06.
756
757=item *
758
759L<ExtUtils::ParseXS> has been upgraded from version 3.31 to 3.34.
760
761=item *
762
763L<ExtUtils::Typemaps> has been upgraded from version 3.31 to 3.34.
764
765=item *
766
767L<feature> has been upgraded from version 1.42 to 1.47.
2c8edc25
S
768
769Fixes the Unicode Bug in the range operator.
a049258c
S
770
771=item *
5c92a635 772
0cc8c746
S
773L<File::Copy> has been upgraded from version 2.31 to 2.32.
774
775=item *
776
777L<File::Fetch> has been upgraded from version 0.48 to 0.52.
778
779=item *
780
781L<File::Glob> has been upgraded from version 1.26 to 1.28.
d5c7a4fc 782
2c8edc25 783Issue a deprecation message for C<File::Glob::glob()>.
d5c7a4fc 784
2c8edc25 785=item *
d5c7a4fc 786
0cc8c746
S
787L<File::Spec> has been upgraded from version 3.63 to 3.67.
788
789=item *
790
791L<FileHandle> has been upgraded from version 2.02 to 2.03.
792
793=item *
794
2c8edc25 795L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
a049258c 796
2c8edc25
S
797It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
798end-of-file. [perl #107726]
64afbd29
DM
799
800=item *
801
0cc8c746
S
802L<Getopt::Long> has been upgraded from version 2.48 to 2.49.
803
804=item *
805
806L<Getopt::Std> has been upgraded from version 1.11 to 1.12.
807
808=item *
809
810L<Hash::Util> has been upgraded from version 0.19 to 0.22.
811
812=item *
813
814L<HTTP::Tiny> has been upgraded from version 0.056 to 0.070.
a049258c 815
2c8edc25 816Internal 599-series errors now include the redirect history.
a049258c 817
2c8edc25 818=item *
a049258c 819
0cc8c746 820L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
a049258c 821
2c8edc25 822It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 823
2c8edc25 824=item *
a049258c 825
0cc8c746
S
826L<IO> has been upgraded from version 1.36 to 1.38.
827
828=item *
829
601d9a87 830IO-Compress has been upgraded from version 2.069 to 2.074.
0cc8c746
S
831
832=item *
833
834L<IO::Socket::IP> has been upgraded from version 0.37 to 0.38.
835
836=item *
837
838L<IPC::Cmd> has been upgraded from version 0.92 to 0.96.
839
840=item *
841
842L<IPC::SysV> has been upgraded from version 2.06_01 to 2.07.
843
844=item *
845
846L<JSON::PP> has been upgraded from version 2.27300 to 2.27400_02.
847
848=item *
849
2c8edc25
S
850L<lib> has been upgraded from version 0.63 to 0.64.
851
852It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
faab9793 853
c714fb1f 854=item *
ad5c8857 855
0cc8c746
S
856L<List::Util> has been upgraded from version 1.42_02 to 1.46_02.
857
858=item *
859
860L<Locale::Codes> has been upgraded from version 3.37 to 3.42.
861
862=item *
863
864L<Locale::Maketext> has been upgraded from version 1.26 to 1.28.
865
866=item *
867
868L<Locale::Maketext::Simple> has been upgraded from version 0.21 to 0.21_01.
869
870=item *
871
872L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
ad5c8857 873
2c8edc25 874There have also been some core customizations.
ad5c8857 875
2c8edc25 876=item *
2e0dcc12 877
0cc8c746
S
878L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
879
880=item *
881
882L<Math::BigRat> has been upgraded from version 0.260802 to 0.2611.
883
884=item *
885
886L<Math::Complex> has been upgraded from version 1.59 to 1.5901.
887
888=item *
889
890L<Memoize> has been upgraded from version 1.03 to 1.03_01.
891
892=item *
893
894L<Module::CoreList> has been upgraded from version 5.20170420 to 5.20170520.
895
896=item *
897
898L<Module::Load::Conditional> has been upgraded from version 0.64 to 0.68.
899
900=item *
901
902L<Module::Metadata> has been upgraded from version 1.000031 to 1.000033.
903
904=item *
905
906L<mro> has been upgraded from version 1.18 to 1.20.
907
908=item *
909
910L<Net::Ping> has been upgraded from version 2.43 to 2.55.
d5c7a4fc 911
2c8edc25
S
912IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
913other enhancements.
d5c7a4fc 914
2c8edc25
S
915Remove sudo from 500_ping_icmp.t.
916
917Avoid stderr noise in tests
918
0f275d26 919Check for echo in new L<Net::Ping> tests.
d5c7a4fc 920
a049258c 921=item *
d5c7a4fc 922
0cc8c746
S
923L<NEXT> has been upgraded from version 0.65 to 0.67.
924
925=item *
926
927L<Opcode> has been upgraded from version 1.34 to 1.39.
928
929=item *
930
931L<open> has been upgraded from version 1.10 to 1.11.
932
933=item *
934
2c8edc25 935L<OS2::Process> has been upgraded from version 1.11 to 1.12.
a049258c 936
2c8edc25 937It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 938
2c8edc25 939=item *
a049258c 940
2c8edc25 941L<overload> has been upgraded from version 1.26 to 1.28.
a049258c 942
2c8edc25 943Its compilation speed has been improved slightly.
a049258c 944
2c8edc25
S
945=item *
946
0cc8c746
S
947L<parent> has been upgraded from version 0.234 to 0.236.
948
949=item *
950
2c8edc25
S
951L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
952
953Ignore F</dev/tty> on non-Unix systems. [perl #113960]
954
955=item *
956
0cc8c746
S
957L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
958
959=item *
960
961L<perlfaq> has been upgraded from version 5.021010 to 5.021011.
962
963=item *
964
965L<PerlIO> has been upgraded from version 1.09 to 1.10.
966
967=item *
968
969L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
970
971=item *
972
973L<PerlIO::scalar> has been upgraded from version 0.24 to 0.26.
974
975=item *
976
977L<Pod::Checker> has been upgraded from version 1.60 to 1.73.
978
979=item *
980
981L<Pod::Functions> has been upgraded from version 1.10 to 1.11.
982
983=item *
984
985L<Pod::Html> has been upgraded from version 1.22 to 1.2202.
986
987=item *
988
989L<Pod::Perldoc> has been upgraded from version 3.25_02 to 3.28.
990
991=item *
992
993L<Pod::Simple> has been upgraded from version 3.32 to 3.35.
994
995=item *
996
997L<Pod::Usage> has been upgraded from version 1.68 to 1.69.
998
999=item *
1000
95b17558 1001L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
2c8edc25
S
1002defects in making its symbols exportable. [perl #127821]
1003The C<POSIX::tmpnam()> interface has been removed,
1004see L</"POSIX::tmpnam() has been removed">.
1005Trying to import POSIX subs that have no real implementations
1006(like C<POSIX::atend()>) now fails at import time, instead of
1007waiting until runtime.
1008
1009=item *
1010
0cc8c746 1011L<re> has been upgraded from version 0.32 to 0.34
2c8edc25
S
1012
1013This adds support for the new L<C<E<47>xx>|perlre/E<sol>x and E<sol>xx>
1014regular expression pattern modifier, and a change to the L<S<C<use re
1015'strict'>>|re/'strict' mode> experimental feature. When S<C<re
1016'strict'>> is enabled, a warning now will be generated for all
df48f9a4 1017unescaped uses of the two characters C<"}"> and C<"]"> in regular
2c8edc25 1018expression patterns (outside bracketed character classes) that are taken
df48f9a4 1019literally. This brings them more in line with the C<")"> character which
2c8edc25
S
1020is always a metacharacter unless escaped. Being a metacharacter only
1021sometimes, depending on action at a distance, can lead to silently
1022having the pattern mean something quite different than was intended,
1023which the S<C<re 'strict'>> mode is intended to minimize.
1024
1025=item *
1026
0cc8c746
S
1027L<Safe> has been upgraded from version 2.39 to 2.40.
1028
1029=item *
1030
1031L<Scalar::Util> has been upgraded from version 1.42_02 to 1.46_02.
1032
1033=item *
1034
1035L<Storable> has been upgraded from version 2.56 to 2.62.
2c8edc25
S
1036
1037Fixes [perl #130098].
1038
1039=item *
1040
0cc8c746
S
1041L<Symbol> has been upgraded from version 1.07 to 1.08.
1042
1043=item *
1044
1045L<Sys::Syslog> has been upgraded from version 0.33 to 0.35.
1046
1047=item *
1048
1049L<Term::ANSIColor> has been upgraded from version 4.04 to 4.06.
1050
1051=item *
1052
2c8edc25
S
1053L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
1054
1055It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1056
1057=item *
1058
0cc8c746 1059L<Test> has been upgraded from version 1.28 to 1.30.
2c8edc25
S
1060
1061It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1062
1063=item *
1064
0cc8c746
S
1065L<Test::Harness> has been upgraded from version 3.36 to 3.38.
1066
1067=item *
1068
1069L<Test::Simple> has been upgraded from version 1.001014 to 1.302073.
1070
1071=item *
1072
1073L<Thread::Queue> has been upgraded from version 3.09 to 3.12.
1074
1075=item *
1076
2c8edc25
S
1077L<Thread::Semaphore> has been upgraded from 2.12 to 2.13.
1078
1079Added the C<down_timed> method.
1080
1081=item *
1082
0cc8c746 1083L<threads> has been upgraded from version 2.07 to 2.15.
2c8edc25
S
1084
1085Compatibility with 5.8 has been restored.
1086
1087Fixes [perl #130469].
1088
1089=item *
1090
0cc8c746 1091L<threads::shared> has been upgraded from version 1.51 to 1.56.
2c8edc25
S
1092
1093This fixes [cpan #119529], [perl #130457]
1094
1095=item *
1096
0cc8c746
S
1097L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
1098
1099=item *
1100
1101L<Time::HiRes> has been upgraded from version 1.9733 to 1.9741.
2c8edc25
S
1102
1103It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
11043.9).
1105
1106Now uses C<clockid_t>.
1107
1108=item *
1109
0cc8c746
S
1110L<Time::Local> has been upgraded from version 1.2300 to 1.25.
1111
1112=item *
1113
1114L<Unicode::Collate> has been upgraded from version 1.14 to 1.19.
1115
1116=item *
1117
1118L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
2c8edc25
S
1119
1120It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1121
1122=item *
1123
0cc8c746
S
1124L<version> has been upgraded from version 0.9916 to 0.9917.
1125
1126=item *
1127
1128L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
2c8edc25
S
1129
1130It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1131
1132=item *
1133
0cc8c746
S
1134L<warnings> has been upgraded from version 1.36 to 1.37.
1135
1136=item *
1137
1138L<XS::Typemap> has been upgraded from version 0.14 to 0.15.
1139
1140=item *
1141
1142L<XSLoader> has been upgraded from version 0.21 to 0.27.
2c8edc25
S
1143
1144Fixed a security hole in which binary files could be loaded from a path
1145outside of L<C<@INC>|perlvar/@INC>.
1146
1147It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1148
1149=back
1150
2c8edc25
S
1151=head1 Documentation
1152
1153=head2 New Documentation
a049258c 1154
2c8edc25 1155=head3 L<perldeprecation>
a049258c 1156
2c8edc25 1157This file documents all upcoming deprecations, and some of the deprecations
95b17558 1158which already have been removed. The purpose of this documentation is
2c8edc25
S
1159two-fold: document what will disappear, and by which version, and serve
1160as a guide for people dealing with code which has features that no longer
1161work after an upgrade of their perl.
a049258c 1162
2c8edc25 1163=head2 Changes to Existing Documentation
a049258c 1164
b10de59c
KW
1165We have attempted to update the documentation to reflect the changes
1166listed in this document. If you find any we have missed, send email to
bfe8fcbb 1167L<perlbug@perl.org|mailto:perlbug@perl.org>.
a049258c 1168
b10de59c
KW
1169Additionally all references to Usenet have been removed, and the
1170following selected changes have been made:
2c8edc25 1171
b10de59c 1172=head3 L<perlfunc>
a049258c 1173
b10de59c 1174=over 4
a049258c 1175
2c8edc25
S
1176=item *
1177
b10de59c
KW
1178Removed obsolete text about L<C<defined()>|perlfunc/defined>
1179on aggregates that should have been deleted earlier, when the feature
1180was removed.
2c8edc25
S
1181
1182=item *
1183
b10de59c
KW
1184Corrected documentation of L<C<eval()>|perlfunc/eval>,
1185and L<C<evalbytes()>|perlfunc/evalbytes>.
a049258c 1186
2c8edc25 1187=item *
a049258c 1188
b10de59c
KW
1189Clarified documentation of L<C<seek()>|perlfunc/seek>,
1190L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>
f9b6dffc 1191emphasizing that positions are in bytes and not characters.
b10de59c 1192L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
2c8edc25
S
1193
1194=item *
1195
b10de59c
KW
1196Clarified documentation of L<C<sort()>|perlfunc/sort LIST> concerning
1197the variables C<$a> and C<$b>.
2c8edc25
S
1198
1199=item *
a049258c 1200
de7be789
KW
1201In L<C<split()>|perlfunc/split> noted that certain pattern modifiers are
1202legal, and added a caution about its use in Perls before v5.11,
a049258c 1203
2c8edc25 1204=item *
a049258c 1205
b10de59c
KW
1206Removed obsolete documentation of L<C<study()>|perlfunc/study>, noting
1207that it is now a no-op.
2c8edc25
S
1208
1209=item *
1210
b10de59c
KW
1211Noted that L<C<vec()>|perlfunc/vec> doesn't work well when the string
1212contains characters whose code points are above 255.
a049258c 1213
2c8edc25 1214=back
a049258c 1215
b10de59c 1216=head3 L<perlguts>
a049258c
S
1217
1218=over 4
1219
1220=item *
1221
b10de59c
KW
1222Added advice on
1223L<formatted printing of operands of C<Size_t> and C<SSize_t>|perlguts/Formatted Printing of Size_t and SSize_t>
a049258c
S
1224
1225=back
1226
b10de59c 1227=head3 L<perlhack>
2c8edc25
S
1228
1229=over 4
1230
1231=item *
1232
7964b3a0
KW
1233Clarify what editor tab stop rules to use, and note that we are
1234migrating away from using tabs, replacing them with sequences of SPACE
1235characters.
2c8edc25
S
1236
1237=back
a049258c 1238
b10de59c 1239=head3 L<perlhacktips>
a049258c
S
1240
1241=over 4
1242
1243=item *
1244
b10de59c 1245Give another reason to use C<cBOOL> to cast an expression to boolean.
2c8edc25
S
1246
1247=item *
1248
b10de59c
KW
1249Note that there are macros C<TRUE> and C<FALSE> available to express
1250boolean values.
a049258c 1251
2c8edc25 1252=back
a049258c 1253
2c8edc25 1254=head3 L<perlinterp>
a049258c
S
1255
1256=over 4
1257
1258=item *
1259
2c8edc25
S
1260L<perlinterp> has been expanded to give a more detailed example of how to
1261hunt around in the parser for how a given operator is handled.
a049258c
S
1262
1263=back
1264
2c8edc25 1265=head3 L<perllocale>
a049258c
S
1266
1267=over 4
1268
a6733086
S
1269=item *
1270
b10de59c
KW
1271Some locales aren't compatible with Perl. Note that these can cause
1272core dumps.
a049258c
S
1273
1274=back
1275
2c8edc25
S
1276=head3 L<perlmodinstall>
1277
1278=over 4
1279
1280=item *
1281
b10de59c 1282Various clarifications have been added.
2c8edc25
S
1283
1284=back
1285
1286=head3 L<perlmodlib>
1287
1288=over 4
1289
1290=item *
1291
b10de59c 1292Updated the site mirror list.
2c8edc25
S
1293
1294=back
1295
1296=head3 L<perlobj>
1297
1298=over 4
1299
1300=item *
1301
1302Added a section on calling methods using their fully qualified names.
1303
1304=item *
1305
0f032fe1 1306Do not discourage manual C<@ISA>.
2c8edc25
S
1307
1308=back
1309
1310=head3 L<perlootut>
1311
1312=over 4
1313
1314=item *
1315
2c8edc25
S
1316Mention C<Moo> more.
1317
1318=back
1319
1320=head3 L<perlop>
1321
1322=over 4
1323
1324=item *
1325
0f275d26 1326Clarify behavior of single quote regexps.
2c8edc25
S
1327
1328=back
1329
1330=head3 L<perlre>
1331
1332=over 4
1333
1334=item *
1335
1c34b59a
KW
1336The first part was extensively rewritten to incorporate various basic
1337points, that in earlier versions were mentioned in sort of an appendix
1338on Version 8 regular expressions.
1339
0cbd1ffa
KW
1340=item *
1341
b10de59c
KW
1342Note that it is common to have the C</x> modifier and forget that this
1343means that C<"#"> has to be escaped.
2c8edc25
S
1344
1345=back
1346
b10de59c 1347=head3 L<perlretut>
2c8edc25
S
1348
1349=over 4
1350
1351=item *
1352
b10de59c 1353Add introductory material
2c8edc25
S
1354
1355=item *
1356
b10de59c
KW
1357Note that a metacharacter occurring in a context where it can't mean
1358that, silently loses its meta-ness and matches literally.
1359L<C<use re 'strict'>|re/'strict' mode> can catch some of these.
2c8edc25
S
1360
1361=back
1362
1363=head3 L<perlunicode>
1364
1365=over 4
1366
1367=item *
1368
b10de59c 1369Corrected the text about Unicode BYTE ORDER MARK handling.
2c8edc25
S
1370
1371=item *
1372
1373Updated the text to correspond with changes in Unicode UTS#18, concerning
1374regular expressions, and Perl compatibility with what it says.
1375
1376=back
1377
1378=head3 L<perlvar>
1379
1380=over 4
1381
1382=item *
1383
95b17558 1384Document C<@ISA>. Was documented other places, not not in L<perlvar>.
2c8edc25
S
1385
1386=back
1387
1388=head1 Diagnostics
1389
1390=head2 New Diagnostics
1391
1392=head3 New Errors
1393
1394=over 4
1395
1396=item *
1397
df48f9a4 1398Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
2c8edc25
S
1399a warning recommending to fix the C<do> statement:
1400
1401L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
1402
1403=item *
1404
1405Using the empty pattern (which re-executes the last successfully-matched
1406pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
95b17558 1407always previously yielded a segfault. It now produces an error:
4f73c567 1408L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
2c8edc25
S
1409
1410=item *
1411
1412L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
1413
1414(F) To declare references to variables, as in C<my \%x>, you must first enable
1415the feature:
1416
1417 no warnings "experimental::declared_refs";
1418 use feature "declared_refs";
1419
1420=item *
1421
1422L<Version control conflict marker|perldiag/"Version control conflict marker">
1423
e6abae1c 1424(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
95b17558 1425C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
2c8edc25
S
1426version control system to mark conflicts after a failed merge operation.
1427
1428=item *
1429
1430L<%s: command not found|perldiag/"%s: command not found">
1431
1432(A) You've accidentally run your script through B<bash> or another shell
1433instead of Perl. Check the #! line, or manually feed your script into
1434Perl yourself. The #! line at the top of your file could look like:
1435
1436 #!/usr/bin/perl
1437
1438=item *
1439
1440L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1441
1442(A) You've accidentally run your script through B<zsh> or another shell
1443instead of Perl. Check the #! line, or manually feed your script into
1444Perl yourself. The #! line at the top of your file could look like:
1445
1446 #!/usr/bin/perl
1447
1448=item *
1449
a6733086 1450L<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 mE<sol>%sE<sol>>
2c8edc25 1451
d8362e1b
KW
1452Unescaped left braces are now illegal in some contexts in regular expression
1453patterns. In other contexts, they are still just deprecated; they will
1454be illegal in Perl 5.30.
2c8edc25
S
1455
1456=item *
1457
1458L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1459
1460=item *
1461
1462L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1463
1464=item *
1465
1466L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1467
1468=item *
1469
1470L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1471
1472=back
1473
1474=head3 New Warnings
1475
1476=over 4
1477
1478=item *
1479
4f73c567 1480L<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
1481
1482See L</Deprecations>
1483
1484=item *
1485
1486L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1487
1488(S experimental::declared_refs) This warning is emitted if you use a reference
1489constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1490C<local()>. Simply suppress the warning if you want to use the feature, but
1491know that in doing so you are taking the risk of using an experimental feature
1492which may change or be removed in a future Perl version:
1493
1494 no warnings "experimental::declared_refs";
1495 use feature "declared_refs";
1496 $fooref = my \$foo;
1497
1498=item *
1499
4f73c567 1500L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25 1501
0f275d26 1502The special variable C<${^ENCODING}>, formerly used to implement
53799a91 1503the C<encoding> pragma, is no longer supported as of Perl 5.26.
2c8edc25 1504
89853d76
DH
1505=item *
1506
df48f9a4 1507Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
89853d76
DH
1508a warning recommending to fix the C<do> statement:
1509
fc902710 1510L<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 1511
2c8edc25
S
1512=back
1513
1514=head2 Changes to Existing Diagnostics
1515
1516=over 4
1517
1518=item *
1519
1520When a C<require> fails, we now do not provide C<@INC> when the C<require>
1521is for a file instead of a module.
1522
1523=item *
1524
1525When C<@INC> is not scanned for a C<require> call, we no longer display
1526C<@INC> to avoid confusion.
1527
1528=item *
1529
1530Attribute "locked" is deprecated, and will disappear in Perl 5.28
1531
1532=item *
1533
1534Attribute "unique" is deprecated, and will disappear in Perl 5.28
1535
1536=item *
1537
1538Constants from lexical variables potentially modified elsewhere are
1539deprecated. This will not be allowed in Perl 5.32
1540
1541=item *
1542
0f032fe1 1543Deprecated use of C<my()> in false conditional. This will be a fatal error
2c8edc25
S
1544in Perl 5.30
1545
1546=item *
1547
0f032fe1 1548C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available
2c8edc25
S
1549in Perl 5.30
1550
1551=item *
1552
1553${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
1554
1555=item *
1556
1557File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
1558instead.
1559
1560=item *
1561
1562%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
1563
1564=item *
1565
1566$* is no longer supported. Its use will be fatal in Perl 5.30
1567
1568=item *
1569
1570$* is no longer supported. Its use will be fatal in Perl 5.30
1571
1572=item *
1573
1574Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1575
1576=item *
1577
1578Opening filehandle %s also as a directory. This will be a fatal
1579error in Perl 5.28
1580
1581=item *
1582
0f032fe1 1583Setting C<$/> to a reference to %s as a form of slurp is deprecated,
2c8edc25
S
1584treating as undef. This will be fatal in Perl 5.28
1585
1586=item *
1587
1588Unescaped left brace in regex is deprecated here (and will be fatal
1589in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
1590
1591=item *
1592
1593Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1594
1595=item *
1596
1597Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1598
1599=item *
1600
1601Use of code point 0x%s is deprecated; the permissible max is 0x%s.
1602This will be fatal in Perl 5.28
1603
1604=item *
1605
1606Use of comma-less variable list is deprecated. Its use will be fatal
1607in Perl 5.28
1608
1609=item *
1610
1611Use of inherited AUTOLOAD for non-method %s() is deprecated. This
1612will be fatal in Perl 5.28
1613
1614=item *
1615
1616Use of strings with code points over 0xFF as arguments to %s operator
1617is deprecated. This will be a fatal error in Perl 5.28
1618
1619=item *
1620
0f032fe1 1621Improve error for missing C<tie()> package/method. This brings the error messages
2c8edc25
S
1622in line with the ones used for normal method calls, despite not using
1623call_method().
1624
1625=item *
1626
0f032fe1
KW
1627Make the C<sysread()>/C<syswrite()> I<etc.>, C<:utf8> handle warnings
1628XXX default. These warnings were under 'deprecated' previously.
2c8edc25
S
1629
1630=item *
1631
0f032fe1 1632C<do> errors now refer to C<do> (not C<require>).
2c8edc25
S
1633
1634=item *
1635
1636Details as to the exact problem have been added to the diagnostics that
1637occur when malformed UTF-8 is encountered when trying to convert to a
1638code point.
1639
1640=item *
1641
1642Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
1643blames the variable for an uninitialized-value warning encountered by the
1644tied/magical code.
1645
1646=item *
1647
2c8edc25
S
1648Code like C<$x = $x . "a"> was incorrectly failing to yield a
1649L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
1650warning when C<$x> was a lexical variable with an undefined value. That has
1651now been fixed. [perl #127877]
1652
1653=item *
1654
1655When the error "Experimental push on scalar is now forbidden" is raised for
1656the hash functions C<keys>, C<each>, and C<values>, it is now followed by
1657the more helpful message, "Type of arg 1 to whatever must be hash or
1658array". [perl #127976]
1659
1660=item *
1661
1662C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
53799a91 1663argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
2c8edc25
S
1664been fixed.
1665
1666=item *
1667
1668C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
1669string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
1670bringing it into consistency with C<$$scalar>.
1671
1672=item *
1673
1674C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
1675do, but merely produce a syntax error. [perl #128171]
1676
1677=item *
1678
1679C<do> or C<require> with a reference or typeglob which, when stringified,
53799a91 1680contains a null character started crashing in Perl 5.20, but has now been
2c8edc25
S
1681fixed. [perl #128182]
1682
1683=back
1684
1685=head1 Utility Changes
1686
1687=head2 F<c2ph> and F<pstruct>
1688
1689=over 4
1690
1691=item *
1692
1693These old utilities have long since superceded by L<h2xs>, and are
1694now gone from the distribution.
1695
1696=back
1697
1698=head2 F<Porting/pod_lib.pl>
1699
1700=over 4
1701
1702=item *
1703
1704Removed spurious executable bit.
1705
1706=item *
1707
fb5d4b1a 1708Account for the possibility of DOS file endings.
2c8edc25
S
1709
1710=back
1711
1712=head2 F<Porting/sync-with-cpan>
1713
1714=over 4
1715
1716=item *
1717
1718Many improvements
1719
1720=back
1721
1722=head2 F<perf/benchmarks>
1723
1724=over 4
1725
1726=item *
1727
1728Tidy file, rename some symbols.
1729
1730=back
1731
1732=head2 F<Porting/checkAUTHORS.pl>
1733
1734=over 4
1735
1736=item *
1737
0f275d26 1738Replace obscure character range with C<\w>.
2c8edc25
S
1739
1740=back
1741
1742=head2 F<t/porting/regen.t>
1743
1744=over 4
1745
1746=item *
1747
1748try to be more helpful when tests fail.
1749
1750=back
1751
1752=head2 F<utils/h2xs.PL>
1753
1754=over 4
1755
1756=item *
1757
1758Avoid infinite loop for enums.
1759
1760=back
1761
1762=head2 L<perlbug>
1763
1764=over 4
1765
1766=item *
1767
1768Long lines in the message body are now wrapped at 900 characters, to stay
1769well within the 1000-character limit imposed by SMTP mail transfer agents.
1770This is particularly likely to be important for the list of arguments to
1771C<Configure>, which can readily exceed the limit if, for example, it names
95b17558 1772several non-default installation paths. This change also adds the first unit
2c8edc25
S
1773tests for perlbug. [perl #128020]
1774
1775=back
1776
1777=head1 Configuration and Compilation
1778
1779=over 4
1780
1781=item *
1782
89853d76 1783C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1784
1785=item *
1786
18618fea 1787The C<dtrace> build process has further changes [perl #130108]:
2c8edc25
S
1788
1789=over
1790
1791=item *
1792
1793If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1794built within a FreeBSD jail.
1795
1796=item *
1797
1798On systems that build a dtrace object file (FreeBSD, Solaris and
1799SystemTap's dtrace emulation), copy the input objects to a separate
1800directory and process them there, and use those objects in the link,
1801since C<dtrace -G> also modifies these objects.
1802
1803=item *
1804
1805Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1806to libelf symbols.
1807
1808=item *
1809
1810Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1811default build on Solaris generates probes from the unused inline
1812functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1813fail.
1814
1815=back
1816
2c8edc25
S
1817=item *
1818
0f032fe1
KW
1819You can now disable perl's use of the C<PERL_HASH_SEED> and
1820C<PERL_PERTURB_KEYS> environment variables by configuring perl with
2c8edc25
S
1821C<-Accflags=NO_PERL_HASH_ENV>.
1822
1823=item *
1824
0f032fe1 1825You can now disable perl's use of the C<PERL_HASH_SEED_DEBUG> environment
2c8edc25
S
1826variable by configuring perl with
1827C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1828
1829=item *
1830
1831Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1832and C<Inf> to make builds more reproducible. [perl #130133]
1833
1834=item *
1835
fb5d4b1a 1836Since v5.18 for testing purposes, we have included support for
2c8edc25 1837building perl with a variety of non-standard, and non-recommended
95b17558
KW
1838hash functions. Since we do not recommend the use of these functions
1839we have removed them and their corresponding build options. Specifically
2c8edc25
S
1840this includes the following build options:
1841
1842 PERL_HASH_FUNC_SDBM
1843 PERL_HASH_FUNC_DJB2
1844 PERL_HASH_FUNC_SUPERFAST
1845 PERL_HASH_FUNC_MURMUR3
1846 PERL_HASH_FUNC_ONE_AT_A_TIME
1847 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1848 PERL_HASH_FUNC_MURMUR_HASH_64A
1849 PERL_HASH_FUNC_MURMUR_HASH_64B
1850
1851=item *
1852
1853Remove "Warning: perl appears in your path"
1854
1855This install warning is more or less obsolete, since most platforms already
0f032fe1 1856B<will> have a F</usr/bin/perl> or similar provided by the OS.
2c8edc25
S
1857
1858=item *
1859
0f032fe1 1860Reduce verbosity of C<make install.man>
2c8edc25
S
1861
1862Previously, two progress messages were emitted for each manpage: one by
1863installman itself, and one by the function in install_lib.pl that it calls to
95b17558 1864actually install the file. Disabling the second of those in each case saves
2c8edc25
S
1865over 750 lines of unhelpful output.
1866
1867=item *
1868
0f032fe1 1869Cleanup for C<clang -Weverything> support. [perl 129961]
2c8edc25
S
1870
1871=item *
1872
1873Configure: signbit scan was assuming too much, stop assuming negative 0.
1874
1875=item *
1876
1877Various compiler warnings have been silenced.
1878
1879=item *
1880
1881Several smaller changes have been made to remove impediments to compiling under
1882C++11.
1883
1884=item *
1885
1886Builds using C<USE_PAD_RESET> now work again; this configuration had
1887bit-rotted.
1888
1889=item *
1890
1891A probe for C<gai_strerror> was added to F<Configure> that checks if the
0f032fe1
KW
1892the C<gai_strerror()> routine is available and can be used to
1893translate error codes returned by C<getaddrinfo()> into human
2c8edc25
S
1894readable strings.
1895
1896=item *
1897
0f032fe1 1898F<Configure> now aborts if both C<-Duselongdouble> and C<-Dusequadmath> are
2c8edc25
S
1899requested.
1900L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1901
1902=item *
1903
0f032fe1 1904Fixed a bug in which F<Configure> could append C<-quadmath> to the archname even
2c8edc25
S
1905if it was already present.
1906L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1907
1908=item *
1909
0f032fe1
KW
1910Clang builds with C<-DPERL_GLOBAL_STRUCT> or
1911C<-DPERL_GLOBAL_STRUCT_PRIVATE> have
2c8edc25
S
1912been fixed (by disabling Thread Safety Analysis for these configurations).
1913
1914=item *
1915
1916F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
1917files require updates. This could cause dependencies, F<perlmain.c>
1918in particular, to be rebuilt unnecessarily. [perl #126710]
1919
1920=item *
1921
1922The output of C<perl -V> has been reformatted so that each configuration
1923and compile-time option is now listed one per line, to improve
1924readability.
1925
1926=item *
1927
1928C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
1929invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
1930This means you can supply your target platform C<config.sh>, generate
1931the headers and proceed to build your cross-target perl. [perl #127234]
1932
1933=item *
1934
1935Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
1936counts when the environment variable C<PERL_TRACE_OPS> to be set to a
1937non-zero integer. This allows C<make test> to pass on such a build.
1938
1939=item *
1940
1941When building with GCC 6 and link-time optimization (the C<-flto> option to
1942C<gcc>), C<Configure> was treating all probed symbols as present on the
95b17558 1943system, regardless of whether they actually exist. This has been fixed.
2c8edc25
S
1944[perl #128131]
1945
1946=item *
1947
1948The F<t/test.pl> library is used for internal testing of Perl itself, and
95b17558 1949also copied by several CPAN modules. Some of those modules must work on
2c8edc25 1950older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
95b17558 1951features. Compatibility with Perl 5.8 was inadvertently removed some time
2c8edc25
S
1952ago; it has now been restored. [perl #128052]
1953
1954=item *
1955
1956The build process no longer emits an extra blank line before building each
1957"simple" extension (those with only F<*.pm> and F<*.pod> files).
1958
1959=back
1960
1961=head1 Testing
1962
dd84ba97
KW
1963Tests were added and changed to reflect the other additions and changes
1964in this release. In addition, these substantive changes were made:
1965
2c8edc25
S
1966=over 4
1967
1968=item *
1969
dd84ba97
KW
1970A new test script, F<comp/parser_run.t>, has been added to test
1971reads through invalid pointers.
2c8edc25
S
1972
1973=item *
1974
1975Tests for locales were erroneously using locales incompatible with Perl.
1976
1977=item *
1978
1979Some parts of the test suite that try to exhaustively test edge cases in the
1980regex implementation have been restricted to running for a maximum of five
95b17558 1981minutes. On slow systems they could otherwise take several hours, without
2c8edc25
S
1982significantly improving our understanding of the correctness of the code
1983under test.
1984
1985In addition, some of those test cases have been split into more files, to
1986allow them to be run in parallel on suitable systems.
1987
1988=item *
1989
1990A new internal facility allows analysing the time taken by the individual
1991tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
1992
1993=item *
1994
1995F<t/re/regexp_nonull.t> has been added to test that the regular expression
1996engine can handle scalars that do not have a null byte just past the end of
1997the string.
1998
1999=item *
2000
2001A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
2002"Declaring a reference to a variable".
2003
2004=item *
2005
dd84ba97
KW
2006A new test script, F<t/re/keep_tabs.t> has been added to contain tests
2007where C<\t> characters should not be expanded into spaces.
2008
2009=item *
2010
2c8edc25
S
2011A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
2012generated by bracketed character classes are as expected.
2013
2014=item *
2015
dd84ba97
KW
2016There is now more extensive testing of the Unicode-related API macros
2017and functions.
2018
2019=item *
2020
2021Several of the longer running API test files have been split into
2022multiple test files so that they can be run in parallel.
2023
2024=item *
2025
2c8edc25
S
2026F<t/harness> now tries really hard not to run tests outside of the Perl
2027source tree. [perl #124050]
2028
2029=back
2030
2031=head1 Platform Support
2032
2033=head2 New Platforms
2034
2035=over 4
2036
2037=item NetBSD/VAX
2038
2039Perl now compiles under NetBSD on VAX machines. However, it's not
2040possible for that platform to implement floating-point infinities and
2041NaNs compatibly with most modern systems, which implement the IEEE-754
2042floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2043literals, C<printf %a>) is not implemented, either.
2044The C<make test> passes 98% of tests.
2045
2046=over 4
2047
2048=item *
2049
2050Test fixes and minor updates.
2051
2052=item *
2053
2054Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2055
2056=back
2057
2058=back
2059
2060=head2 Platform-Specific Notes
2061
2062=over 4
2063
2064=item Darwin
2065
0f032fe1
KW
2066don't treat C<-Dprefix=/usr> as special, instead require an extra option
2067C<-Ddarwin_distribution> to produce the same results.
2c8edc25
S
2068
2069=item POSIX
2070
2071Finish removing POSIX deprecated functions.
2072
2073=item OS X
2074
0f032fe1
KW
2075OS X El Capitan doesn't implement the C<clock_gettime()> or
2076C<clock_getres()> APIs; emulate them as necessary.
2c8edc25
S
2077
2078=item macOS
2079
0f032fe1 2080Deprecated C<syscall(2)> on macOS 10.12.
2c8edc25
S
2081
2082=item EBCDIC
2083
2084Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2085
2086=item HP-UX
2087
2088L<Net::Ping> UDP test is skipped on HP-UX.
2089
2090=item Hurd
2091
2092The hints for Hurd have been improved enabling malloc wrap and reporting the
2093GNU libc used (previously it was an empty string when reported).
2094
2095=item VAX
2096
29ce4d71 2097VAX floating point formats are now supported on NetBSD.
2c8edc25
S
2098
2099=item VMS
2100
2101=over 4
2102
2103=item *
2104
2105The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
df48f9a4
KW
2106now a colon (C<":">) when running under a Unix shell. There is no change when
2107running under DCL (it's still C<"|">).
2c8edc25
S
2108
2109=item *
2110
29ce4d71
CB
2111C<configure.com> now recognizes the VSI-branded C compiler and no longer
2112recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
211315 or more years).
2c8edc25
S
2114
2115=back
2116
2117=item Windows
2118
2119=over 4
2120
2121=item *
2122
2123Support for compiling perl on Windows using Microsoft Visual Studio 2015
2124(containing Visual C++ 14.0) has been added.
2125
2126This version of VC++ includes a completely rewritten C run-time library, some
0f032fe1
KW
2127of the changes in which mean that work done to resolve a socket
2128C<close()> bug in
2c8edc25
S
2129perl #120091 and perl #118059 is not workable in its current state with this
2130version of VC++. Therefore, we have effectively reverted that bug fix for
2131VS2015 onwards on the basis that being able to build with VS2015 onwards is
2132more important than keeping the bug fix. We may revisit this in the future to
2133attempt to fix the bug again in a way that is compatible with VS2015.
2134
2135These changes do not affect compilation with GCC or with Visual Studio versions
fce64130 2136up to and including VS2013, I<i.e.>, the bug fix is retained (unchanged) for those
2c8edc25
S
2137compilers.
2138
2139Note that you may experience compatibility problems if you mix a perl built
2140with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2141perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2142Some incompatibility may arise because of the bug fix that has been reverted
2143for VS2015 builds of perl, but there may well be incompatibility anyway because
fce64130 2144of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
2c8edc25
S
2145http://stackoverflow.com/questions/30412951).
2146
2147=back
2148
2149=item Win32
2150
2151=over 4
2152
2153=item *
2154
95b17558 2155Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2c8edc25 2156depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
95b17558 2157the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2c8edc25
S
2158
2159=item *
2160
2161fp definitions have been updated.
2162
2163=back
2164
2c8edc25
S
2165=item Linux
2166
2167Drop support for Linux a.out Linux has used ELF for over twenty years.
2168
2169=item OpenBSD 6
2170
2171OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2172Make sure this is accounted for.
2173
2174=item FreeBSD
2175
0f032fe1 2176F<t/uni/overload.t>: Skip hanging test on FreeBSD.
2c8edc25
S
2177
2178=back
2179
2180=head1 Internal Changes
2181
2182=over 4
2183
2184=item *
2185
c2ef64b1
DM
2186A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
2187length and allocated size of the buffer in an C<SV>, growing the buffer if
2188necessary.
2c8edc25
S
2189
2190=item *
2191
c2ef64b1
DM
2192A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
2193like Perl-space C<$x = ''>, but with several optimisations.
2c8edc25
S
2194
2195=item *
2196
c11f9206 2197Several new macros and functions for dealing with Unicode and
fb5d4b1a
KW
2198UTF-8-encoded strings have been added to the API, as well as some
2199changes in
c11f9206
DM
2200functionality of existing functions (see L<perlapi/Unicode Support> for
2201more details):
2202
2203=over
2204
2205=item *
2206
2c8edc25
S
2207New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
2208been added, each with the
2209suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
2210parameter, giving an upper limit of how far into the string it is safe
2211to read. Using the old versions could cause attempts to read beyond the
2212end of the input buffer if the UTF-8 is not well-formed, and their use
2213now raises a deprecation warning. Details are at
2214L<perlapi/Character classification>.
2215
2216=item *
2217
2218Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
53799a91 2219deprecation warning since Perl 5.18. They now die.
2c8edc25
S
2220Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
2221
2222=item *
2223
c11f9206
DM
2224Several new macros for analysing the validity of utf8 sequences. These
2225are:
2226
bfe8fcbb
KW
2227L<C<UTF8_GOT_ABOVE_31_BIT>|perlapi/UTF8_GOT_ABOVE_31_BIT>
2228L<C<UTF8_GOT_CONTINUATION>|perlapi/UTF8_GOT_CONTINUATION>
2229L<C<UTF8_GOT_EMPTY>|perlapi/UTF8_GOT_EMPTY>
2230L<C<UTF8_GOT_LONG>|perlapi/UTF8_GOT_LONG>
2231L<C<UTF8_GOT_NONCHAR>|perlapi/UTF8_GOT_NONCHAR>
2232L<C<UTF8_GOT_NON_CONTINUATION>|perlapi/UTF8_GOT_NON_CONTINUATION>
2233L<C<UTF8_GOT_OVERFLOW>|perlapi/UTF8_GOT_OVERFLOW>
2234L<C<UTF8_GOT_SHORT>|perlapi/UTF8_GOT_SHORT>
2235L<C<UTF8_GOT_SUPER>|perlapi/UTF8_GOT_SUPER>
2236L<C<UTF8_GOT_SURROGATE>|perlapi/UTF8_GOT_SURROGATE>
2237L<C<UTF8_IS_INVARIANT>|perlapi/UTF8_IS_INVARIANT>
2238L<C<UTF8_IS_NONCHAR>|perlapi/UTF8_IS_NONCHAR>
2239L<C<UTF8_IS_SUPER>|perlapi/UTF8_IS_SUPER>
2240L<C<UTF8_IS_SURROGATE>|perlapi/UTF8_IS_SURROGATE>
2241L<C<UVCHR_IS_INVARIANT>|perlapi/UVCHR_IS_INVARIANT>
2242L<C<isUTF8_CHAR_flags>|perlapi/isUTF8_CHAR_flags>
2243L<C<isSTRICT_UTF8_CHAR>|perlapi/isSTRICT_UTF8_CHAR>
2244L<C<isC9_STRICT_UTF8_CHAR>|perlapi/isC9_STRICT_UTF8_CHAR>
2c8edc25
S
2245
2246=item *
2247
0f032fe1 2248Functions that are all extensions of the C<is_utf8_string_I<*>()> functions,
c11f9206
DM
2249that apply various restrictions to the UTF-8 recognized as valid:
2250
bfe8fcbb
KW
2251L<C<is_strict_utf8_string>|perlapi/is_strict_utf8_string>,
2252L<C<is_strict_utf8_string_loc>|perlapi/is_strict_utf8_string_loc>,
2253L<C<is_strict_utf8_string_loclen>|perlapi/is_strict_utf8_string_loclen>,
c11f9206 2254
bfe8fcbb
KW
2255L<C<is_c9strict_utf8_string>|perlapi/is_c9strict_utf8_string>,
2256L<C<is_c9strict_utf8_string_loc>|perlapi/is_c9strict_utf8_string_loc>,
2257L<C<is_c9strict_utf8_string_loclen>|perlapi/is_c9strict_utf8_string_loclen>,
c11f9206 2258
bfe8fcbb
KW
2259L<C<is_utf8_string_flags>|perlapi/is_utf8_string_flags>,
2260L<C<is_utf8_string_loc_flags>|perlapi/is_utf8_string_loc_flags>,
2261L<C<is_utf8_string_loclen_flags>|perlapi/is_utf8_string_loclen_flags>,
c11f9206 2262
bfe8fcbb
KW
2263L<C<is_utf8_fixed_width_buf_flags>|perlapi/is_utf8_fixed_width_buf_flags>,
2264L<C<is_utf8_fixed_width_buf_loc_flags>|perlapi/is_utf8_fixed_width_buf_loc_flags>,
2265L<C<is_utf8_fixed_width_buf_loclen_flags>|perlapi/is_utf8_fixed_width_buf_loclen_flags>.
c11f9206 2266
bfe8fcbb
KW
2267L<C<is_utf8_invariant_string>|perlapi/is_utf8_invariant_string>.
2268L<C<is_utf8_valid_partial_char>|perlapi/is_utf8_valid_partial_char>.
2269L<C<is_utf8_valid_partial_char_flags>|perlapi/is_utf8_valid_partial_char_flags>.
2c8edc25
S
2270
2271=item *
2272
bfe8fcbb
KW
2273The functions L<C<utf8n_to_uvchr>|perlapi/utf8n_to_uvchr> and its
2274derivatives have had several changes of behaviour.
c11f9206
DM
2275
2276Calling them, while passing a string length of 0 is now asserted against
2277in DEBUGGING builds, and otherwise returns the Unicode REPLACEMENT
2278CHARACTER. If you have nothing to decode, you shouldn't call the decode
2279function.
2280
2281They now return the Unicode REPLACEMENT CHARACTER if called with UTF-8
2282that has the overlong malformation, and that malformation is allowed by
2283the input parameters. This malformation is where the UTF-8 looks valid
2284syntactically, but there is a shorter sequence that yields the same code
2285point. This has been forbidden since Unicode version 3.1.
2286
2287They now accept an input
2c8edc25
S
2288flag to allow the overflow malformation. This malformation is when the
2289UTF-8 may be syntactically valid, but the code point it represents is
2290not capable of being represented in the word length on the platform.
2291What "allowed" means in this case is that the function doesn't return an
fb5d4b1a
KW
2292error, and it advances the parse pointer to beyond the UTF-8 in
2293question, but it returns the Unicode REPLACEMENT CHARACTER as the value
2294of the code point (since the real value is not representable).
2c8edc25 2295
c11f9206 2296C<utf8n_to_uvchr> has been changed to not
2c8edc25
S
2297abandon searching for other malformations when the first one is
2298encountered. A call to it thus can generate multiple diagnostics,
2299instead of just one.
2300
2301=item *
2302
c11f9206
DM
2303C<valid_utf8_to_uvchr()> has been added to the API (although it was
2304present in core earlier). Like C<utf8_to_uvchr_buf()>, but assumes that
fb5d4b1a 2305the next character is well-formed. Use with caution.
c11f9206
DM
2306
2307=item *
2308
bfe8fcbb
KW
2309A new function, L<C<utf8n_to_uvchr_error>|perlapi/utf8n_to_uvchr_error>,
2310has been added for
2c8edc25
S
2311use by modules that need to know the details of UTF-8 malformations
2312beyond pass/fail. Previously, the only ways to know why a sequence was
2313ill-formed was to capture and parse the generated diagnostics, or to do
2314your own analysis.
2315
2316=item *
2317
c11f9206
DM
2318There is now a safer version of utf8_hop(), called utf8_hop_safe().
2319Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or
2320after the end of the supplied buffer.
2c8edc25
S
2321
2322=item *
2323
c11f9206
DM
2324Two new functions, C<utf8_hop_forward()> and C<utf8_hop_back()> are
2325similar to C<utf8_hop_safe()> but are for when you know which direction
2326you wish to travel.
2c8edc25
S
2327
2328=item *
2329
c11f9206
DM
2330Two new macros which return useful utf8 byte sequences:
2331
bfe8fcbb
KW
2332L<C<BOM_UTF8>|perlapi/BOM_UTF8>
2333L<C<REPLACEMENT_CHARACTER_UTF8>|perlapi/REPLACEMENT_CHARACTER_UTF8>
c11f9206
DM
2334
2335=back
c2ef64b1
DM
2336
2337=item *
2338
2339Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
2340default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2341This flag alters how the C<op_sibling> field is used in C<OP> structures,
2342and has been available optionally since perl 5.22.
2343
2344See L<perl5220delta/"Internal Changes"> for more details of what this
2345build option does.
2346
2347=item *
2348
2349Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
2350been added. These are intended principally to implement the individual
2351elements of a subroutine signature, plus any overall checking required.
2352
2353=item *
2354
2355The C<op_class()> API function has been added. This is like the existing
2356C<OP_CLASS()> macro, but can more accurately determine what struct an op
2357has been allocated as. For example C<OP_CLASS()> might return
2358C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2359allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2360C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2c8edc25
S
2361
2362=item *
2363
2364All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2365previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2366that several parts of the internals had to be special-cased to accommodate
95b17558 2367it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2c8edc25
S
2368that is now handled in a simpler way.
2369
2370=item *
2371
c2ef64b1
DM
2372The output format of the C<op_dump()> function (as used by C<perl -Dx>)
2373has changed: it now displays an "ASCII-art" tree structure, and shows more
2374low-level details about each op, such as its address and class.
2c8edc25
S
2375
2376=item *
2377
c2ef64b1
DM
2378The C<PADOFFSET> type has changed from being unsigned to signed, and
2379several pad-related variables such as C<PL_padix> have changed from being
2380of type C<I32> to type C<PADOFFSET>.
2c8edc25
S
2381
2382=item *
2383
c2ef64b1
DM
2384The C<DEBUGGING>-mode output for regex compilation and execution has been
2385enhanced.
2c8edc25
S
2386
2387=item *
2388
74ca8c9e
DM
2389Several obscure SV flags have been eliminated, sometimes along with the
2390macros which manipulate them: C<SVpbm_VALID>, C<SVpbm_TAIL>, C<SvTAIL_on>,
2391C<SvTAIL_off>, C<SVrepl_EVAL>, C<SvEVALED>
2c8edc25
S
2392
2393=item *
2394
74ca8c9e
DM
2395An OP op_private flag has been eliminated: C<OPpRUNTIME>. This used to
2396often get set on C<PMOP>s, but had become meaningless over time.
2c8edc25
S
2397
2398=back
2399
2400=head1 Selected Bug Fixes
2401
2402=over 4
2403
2404=item *
2405
5573eafe
DM
2406Perl no longer panics when switching into some locales on machines with
2407buggy C<strxfrm()> implementations in their libc. [perl #121734]
2408
2409=item *
2410
2c8edc25
S
2411C< $-{$name} > would leak an C<AV> on each access if the regular
2412expression had no named captures. The same applies to access to any
2413hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2414#130822]
2415
2416=item *
2417
2418Attempting to use the deprecated variable C<$#> as the object in an
2419indirect object method call could cause a heap use after free or
2420buffer overflow. [perl #129274]
2421
2422=item *
2423
2424When checking for an indirect object method call in some rare cases
2425the parser could reallocate the line buffer but then continue to use
2426pointers to the old buffer. [perl #129190]
2427
2428=item *
2429
0f032fe1
KW
2430Supplying a glob as the format argument to
2431L<C<formline>|perlfunc/formline> would
2c8edc25
S
2432cause an assertion failure. [perl #130722]
2433
2434=item *
2435
2436Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
0f032fe1 2437converted into a C<qr//> operator, leaving extra elements on the stack to
2c8edc25
S
2438confuse any surrounding expression. [perl #130705]
2439
2440=item *
2441
d3972b39 2442Since v5.24 in some obscure cases, a regex which included code blocks
0f032fe1 2443from multiple sources (I<e.g.>, via embedded via C<qr//> objects) could end up
2c8edc25
S
2444with the wrong current pad and crash or give weird results. [perl #129881]
2445
2446=item *
2447
2448Occasionally C<local()>s in a code block within a patterns weren't being
2449undone when the pattern matching backtracked over the code block.
2450[perl #126697]
2451
2452=item *
2453
2454Using C<substr()> to modify a magic variable could access freed memory
2455in some cases. [perl #129340]
2456
2457=item *
2458
2c8edc25 2459Under C<use utf8>, the entire Perl program is now checked that the UTF-8
fb5d4b1a 2460is wellformed. [perl #126310].
2c8edc25
S
2461
2462=item *
2463
df48f9a4 2464The range operator C<".."> on strings now handles its arguments correctly when in
2c8edc25 2465the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
95b17558 2466feature. The previous behaviour was sufficiently unexpected that we believe no
2c8edc25
S
2467correct program could have made use of it.
2468
2469=item *
2470
0f032fe1 2471The C<split> operator did not ensure enough space was allocated for
2c8edc25
S
2472its return value in scalar context. It could then write a single
2473pointer immediately beyond the end of the memory block allocated for
2474the stack. [perl #130262]
2475
2476=item *
2477
df48f9a4 2478Using a large code point with the C<"W"> pack template character with
2c8edc25
S
2479the current output position aligned at just the right point could
2480cause a write a single zero byte immediately beyond the end of an
2481allocated buffer. [perl #129149]
2482
2483=item *
2484
2485Supplying the form picture argument as part of the form argument list
2486where the picture specifies modifying the argument could cause an
2487access to the new freed compiled form. [perl #129125]
2488
2489=item *
2490
2491Fix a problem with sort's build-in compare, where it would not sort
2492correctly with 64-bit integers, and non-long doubles. [perl #130335]
2493
2494=item *
2495
0f032fe1 2496Fix issues with C</(?{ ... E<lt>E<lt>EOF })/> that broke Method-Signatures. [perl #130398]
2c8edc25
S
2497
2498=item *
2499
2500Fix a macro which caused syntax error on an EBCDIC build.
2501
2502=item *
2503
2504Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2505
2506=item *
2507
2508Fixed an assertion failure with C<chop> and C<chomp>, which
2509could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2510
2511=item *
2512
fb5d4b1a
KW
2513Fixed a comment skipping error in patterns under C</x>; it could stop
2514skipping a byte early, which could be in the middle of a UTF-8
2515character. [perl #130495].
2c8edc25
S
2516
2517=item *
2518
2519F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2520
2521=item *
2522
2523Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2524
2525=item *
2526
0f032fe1 2527DragonFly BSD now has support for C<setproctitle()>. [perl #130068].
2c8edc25
S
2528
2529=item *
2530
fb5d4b1a 2531Fix an assertion error which could be triggered when a lookahead string
2c8edc25
S
2532in patterns exceeded a minimum length. [perl #130522].
2533
2534=item *
2535
df48f9a4 2536Only warn once per literal about a misplaced C<"_">. [perl #70878].
2c8edc25
S
2537
2538=item *
2539
2540Ensure range-start is set after error in C<tr///>. [perl #129342].
2541
2542=item *
2543
2544Don't read past start of string for unmatched backref; otherwise,
2545we may have heap buffer overflow. [perl #129377].
2546
2547=item *
2548
2c8edc25 2549C<use re 'strict'> is supposed to warn if you use a range whose start
95b17558 2550and end digit aren't from the same group of 10. It didn't do that
2c8edc25
S
2551for five groups of mathematical digits starting at U+1D7E.
2552
2553=item *
2554
fce64130 2555A sub containing a "forward" declaration with the same name (I<e.g.>,
2c8edc25
S
2556C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2557#129090]
2558
2559=item *
2560
fb5d4b1a 2561A crash in executing a regex with a non-anchored UTF-8 substring against a
2c8edc25
S
2562target string that also used UTF-8 has been fixed. [perl #129350]
2563
2564=item *
2565
2566Previously, a shebang line like C<#!perl -i u> could be erroneously
95b17558 2567interpreted as requesting the C<-u> option. This has been fixed. [perl
2c8edc25
S
2568#129336]
2569
2570=item *
2571
2572The regex engine was previously producing incorrect results in some rare
2573situations when backtracking past a trie that matches only one thing; this
0f032fe1 2574showed up as capture buffers (C<$1>, C<$2>, I<etc.>) erroneously containing data
2c8edc25
S
2575from regex execution paths that weren't actually executed for the final
2576match. [perl #129897]
2577
2578=item *
2579
2580Certain regexes making use of the experimental C<regex_sets> feature could
95b17558 2581trigger an assertion failure. This has been fixed. [perl #129322]
2c8edc25
S
2582
2583=item *
2584
fce64130 2585Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
2c8edc25
S
2586sometimes crash in addition to giving a syntax error. [perl #125679]
2587
2588=item *
2589
2590The parser could sometimes crash if a bareword came after C<evalbytes>.
2591[perl #129196]
2592
2593=item *
2594
2595Autoloading via a method call would warn erroneously ("Use of inherited
2596AUTOLOAD for non-method") if there was a stub present in the package into
2597which the invocant had been blessed. The warning is no longer emitted in
2598such circumstances. [perl #47047]
2599
2600=item *
2601
2c8edc25
S
2602The use of C<splice> on arrays with nonexistent elements could cause other
2603operators to crash. [perl #129164]
2604
2605=item *
2606
2607Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2608string. [perl #129012]
2609
2610=item *
2611
2612Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2613checking that the I<current> C<cx> is the right type, and instead was always
2614checking the base C<cx> (effectively a noop). [perl #129029]
2615
2616=item *
2617
95b17558 2618Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2c8edc25
S
2619maintains up to two pointers into the parser buffer, one of which can
2620become stale under the right conditions. [perl #129069]
2621
2622=item *
2623
2624Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2625when it wasn't. [perl #129038]
2626
2627=item *
2628
2629Fixed place where regex was not setting the syntax error correctly.
2630[perl #129122]
2631
2632=item *
2633
df48f9a4 2634The C<&.> operator (and the C<"&"> operator, when it treats its arguments as
2c8edc25
S
2635strings) were failing to append a trailing null byte if at least one string
2636was marked as utf8 internally. Many code paths (system calls, regexp
2637compilation) still expect there to be a null byte in the string buffer
2638just past the end of the logical string. An assertion failure was the
2639result. [perl #129287]
2640
2641=item *
2642
2643Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2644silently truncates the supplied path if it won't fit into the C<sun_path>
95b17558 2645member of C<sockaddr_un>. This may change in the future, but for now
2c8edc25
S
2646check the path in theC<sockaddr> matches the desired path, and skip if
2647it doesn't. [perl #128095]
2648
2649=item *
2650
95b17558 2651Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2c8edc25
S
2652cases this is used in building error messages. [perl #128988]
2653
2654=item *
2655
2656Check for null PL_curcop in IN_LC() [perl #129106]
2657
2658=item *
2659
2660Fixed the parser error handling for an 'C<:attr(foo>' that does not have
df48f9a4 2661an ending 'C<")">'.
2c8edc25
S
2662
2663=item *
2664
2665Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2666actually fixed two bugs, [perl #129064] and [perl #129176].
2667
2668=item *
2669
0f032fe1
KW
2670[perl #129267] rework C<gv_fetchmethod_pvn_flags> separator parsing to
2671prevent possible string overrun with invalid len in F<gv.c>
2c8edc25
S
2672
2673=item *
2674
2675Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2676where the source and destination of the sort are the same plain array, are
95b17558 2677optimised to do less copying around. Two side-effects of this optimisation
2c8edc25
S
2678were that the contents of C<@a> as visible to to sort routine were
2679partially sorted, and under some circumstances accessing C<@a> during the
95b17558 2680sort could crash the interpreter. Both these issues have been fixed, and
2c8edc25
S
2681Sort functions see the original value of C<@a>.
2682
2683=item *
2684
2685Non-ASCII string delimiters are now reported correctly in error messages
2686for unterminated strings. [perl #128701]
2687
2688=item *
2689
2690C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2691temporary value") erroneously in some cases, but has been fixed.
2692
2693=item *
2694
2695C<@DB::args> is now exempt from "used once" warnings. The warnings only
2696occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2697multiple times.
2698
2699=item *
2700
2701The use of built-in arrays or hash slices in a double-quoted string no
2702longer issues a warning ("Possible unintended interpolation...") if the
2703variable has not been mentioned before. This affected code like
2704C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2705C<@-> and C<@+> were already exempt from the warning.)
2706
2707=item *
2708
2709C<gethostent> and similar functions now perform a null check internally, to
d3972b39 2710avoid crashing with torsocks. This was a regression from v5.22. [perl
2c8edc25
S
2711#128740]
2712
2713=item *
2714
2715C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2716memory if the typeglob in question has never been accessed before.
2717
2718=item *
2719
2c8edc25
S
2720Mentioning the same constant twice in a row (which is a syntax error) no
2721longer fails an assertion under debugging builds. This was a regression
d3972b39 2722from v5.20. [perl #126482]
2c8edc25
S
2723
2724=item *
2725
2726Many issues relating to C<printf "%a"> of hexadecimal floating point
2727were fixed. In addition, the "subnormals" (formerly known as "denormals")
fb5d4b1a 2728floating point numbers are now supported both with the plain IEEE 754
2c8edc25
S
2729floating point numbers (64-bit or 128-bit) and the x86 80-bit
2730"extended precision". Note that subnormal hexadecimal floating
2731point literals will give a warning about "exponent underflow".
2732[perl #128843, #128889, #128890, #128893, #128909, #128919]
2733
2734=item *
2735
d3972b39 2736A regression in v5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2c8edc25
S
2737128 and 255 has been fixed. [perl #128734].
2738
2739=item *
2740
2c8edc25
S
2741Use of a string delimiter whose code point is above 2**31 now works
2742correctly on platforms that allow this. Previously, certain characters,
2743due to truncation, would be confused with other delimiter characters
df48f9a4 2744with special meaning (such as C<"?"> in C<m?...?>), resulting
2c8edc25
S
2745in inconsistent behaviour. Note that this is non-portable,
2746and is based on Perl's extension to UTF-8, and is probably not
2747displayable nor enterable by any editor. [perl #128738]
2748
2749=item *
2750
df48f9a4 2751C<@{x> followed by a newline where C<"x"> represents a control or non-ASCII
2c8edc25
S
2752character no longer produces a garbled syntax error message or a crash.
2753[perl #128951]
2754
2755=item *
2756
2757An assertion failure with C<%: = 0> has been fixed.
2758L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2759
2760=item *
2761
2762In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2763that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2764was to parse it as C<$foo:: . $bar>, has been restored.
2765L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2766
2767=item *
2768
2769Since Perl 5.20, line numbers have been off by one when perl is invoked with
2770the B<-x> switch. This has been fixed.
2771L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2772
2773=item *
2774
fce64130 2775Vivifying a subroutine stub in a deleted stash (I<e.g.>, C<delete $My::{"Foo::"};
2c8edc25
S
2776\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2777L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2778
2779=item *
2780
2781Some obscure cases of subroutines and file handles being freed at the same time
2782could result in crashes, but have been fixed. The crash was introduced in Perl
27835.22.
2784L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2785
2786=item *
2787
2788Code that looks for a variable name associated with an uninitialized value
fb5d4b1a 2789could cause an assertion failure in cases where magic is involved, such as
2c8edc25
S
2790C<$ISA[0][0]>. This has now been fixed.
2791L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2792
2793=item *
2794
2795A crash caused by code generating the warning "Subroutine STASH::NAME
2796redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2797fixed. In these cases, where the STASH is missing, the warning will now appear
2798as "Subroutine NAME redefined".
2799L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2800
2801=item *
2802
2803Fixed an assertion triggered by some code that handles deprecated behavior in
fce64130 2804formats, I<e.g.>, in cases like this:
2c8edc25
S
2805
2806 format STDOUT =
2807 @
2808 0"$x"
2809
2810L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2811
2812=item *
2813
2814A possible divide by zero in string transformation code on Windows has been
2815avoided, fixing a crash when collating an empty string.
2816L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2817
2818=item *
2819
2820Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2821regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2822L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2823
2824=item *
2825
2826C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2827warn when syntax warnings are enabled. [perl #127333]
2828
2829=item *
2830
2831socket() now leaves the error code returned by the system in C<$!> on
2832failure. [perl #128316]
2833
2834=item *
2835
2836Assignment variants of any bitwise ops under the C<bitwise> feature would
2837crash if the left-hand side was an array or hash. [perl #128204]
2838
2839=item *
2840
2841C<require> followed by a single colon (as in C<foo() ? require : ...> is
0f032fe1 2842now parsed correctly as C<require> with implicit C<$_>, rather than
2c8edc25
S
2843C<require "">. [perl #128307]
2844
2845=item *
2846
2847Scalar C<keys %hash> can now be assigned to consistently in all scalar
2848lvalue contexts. Previously it worked for some contexts but not others.
2849
2850=item *
2851
2852List assignment to C<vec> or C<substr> with an array or hash for its first
2853argument used to result in crashes or "Can't coerce" error messages at run
2854time, unlike scalar assignment, which would give an error at compile time.
2855List assignment now gives a compile-time error, too. [perl #128260]
2856
2857=item *
2858
2859Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
95b17558 2860and C<or>) were being compiled incorrectly in some cases. If the left-hand
2c8edc25
S
2861side consisted of either a negated bareword constant or a negated C<do {}>
2862block containing a constant expression, and the right-hand side consisted of
2863a negated non-foldable expression, one of the negations was effectively
95b17558
KW
2864ignored. The same was true of C<if> and C<unless> statement modifiers,
2865though with the left-hand and right-hand sides swapped. This long-standing
2c8edc25
S
2866bug has now been fixed. [perl #127952]
2867
2868=item *
2869
2870C<reset> with an argument no longer crashes when encountering stash entries
2871other than globs. [perl #128106]
2872
2873=item *
2874
2875Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2876longer causes crashes. [perl #128086]
2877
2878=item *
2879
0f032fe1 2880Handle C<SvIMMORTALs> in LHS of list assign. [perl #129991]
2c8edc25
S
2881
2882=item *
2883
fc751fe1 2884Assertion failure with user-defined Unicode-like properties. [perl #130010]
2c8edc25
S
2885
2886=item *
2887
2888Fix error message for unclosed C<\N{> in regcomp.
2889
2890An unclosed C<\N{> could give the wrong error message
2891C<"\N{NAME} must be resolved by the lexer">.
2892
2893=item *
2894
2895List assignment in list context where the LHS contained aggregates and
2896where there were not enough RHS elements, used to skip scalar lvalues.
2897Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
95b17558
KW
2898it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2899returns C<($a,$b,$c)>. This can be seen in the following:
2c8edc25
S
2900
2901 sub inc { $_++ for @_ }
2902 inc(($a,$b,@c,$d) = (10))
2903
2904Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2905now they are C<(11,1,1)>.
2906
2907=item *
2908
f632cffa
KW
2909Code like this: C</(?{ s!!! })/> can trigger infinite recursion on the C
2910stack (not the normal perl stack) when the last successful pattern in
2911scope is itself. We avoid the segfault by simply forbidding the use of
2912the empty pattern when it would resolve to the currently executing
2913pattern. [perl 129903]
2c8edc25
S
2914
2915=item *
2916
0c092f6b
KW
2917Avoid reading beyond the end of the line buffer when there's a
2918short UTF-8 character at the end. [perl 128997]
2c8edc25
S
2919
2920=item *
2921
0c092f6b 2922Fix firstchar bitmap under utf8 with prefix optimisation. [perl 129950]
2c8edc25
S
2923
2924=item *
2925
0c092f6b 2926Make F<Carp/t/arg_string.t>: be liberal in C<f>/C<p> formats. [perl 129954]
2c8edc25
S
2927
2928=item *
2929
0c092f6b 2930Make C<do "a\0b"> fail silently instead of throwing an error. [perl 129928]
2c8edc25
S
2931
2932=item *
2933
0c092f6b 2934Make C<chdir> allocate the stack it needs. [perl 129130]
2c8edc25
S
2935
2936=back
2937
2938=head1 Known Problems
2939
2940=over 4
2941
2942=item *
2943
2944Some modules have been broken by the L<context stack rework|/Internal Changes>.
fb5d4b1a
KW
2945These modules were relying on non-guaranteed implementation details in
2946the perl interpreter.
2c8edc25
S
2947Their maintainers have been informed, and should contact perl5-porters for
2948advice if needed. Below is a subset of these modules:
2949
2950=over 4
2951
2952=item * L<Algorithm::Permute>
2953
2954=item * L<Coro>
2955
fb5d4b1a
KW
2956L<Coro> and Perl 5.22 were already incompatible due to a change in the perl
2957interpreter,
2c8edc25
S
2958and the reworking on the perl context stack creates a further incompatibility.
2959perl5-porters has L<discussed the issue on the mailing
2960list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
2961
2962=item * L<Data::Alias>
2963
2964=item * L<RPerl>
2965
2966=item * L<Scope::Upper>
2967
2968=item * L<TryCatch>
2969
2970=back
2971
2972=item *
2973
53799a91 2974The module L<lexical::underscore> no longer works on Perl 5.24, because perl
2c8edc25
S
2975no longer has a lexical C<$_>!
2976
2977=item *
2978
53799a91 2979C<mod_perl> has been patched for compatibility for v5.22 and later but no
2c8edc25
S
2980release has been made. The relevant patch (and other changes) can be found in
2981their source code repository, L<mirrored at
2982GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
2983
2984=back
2985
2986=head1 Errata From Previous Releases
2987
2988=over 4
2989
2990=item *
2991
ee8180b8 2992Parsing bad POSIX charclasses no longer leaks memory.
2c8edc25
S
2993L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
2994
2995=item *
2996
53799a91 2997Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
2c8edc25
S
2998L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
2999
3000=back
3001
3002=head1 Obituary
3003
3004Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
95b17558 3005member, has passed away on August 10, 2016. He will be remembered and
c94c0e4f 3006missed by all those who he came in contact with, and enriched with his
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3007intellect, wit, and spirit.
3008
c94c0e4f 3009It is with great sadness that we also note Kip Hampton's passing. Probably
2c8edc25
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3010best known as the author of the Perl & XML column on XML.com, he was a
3011core contributor to AxKit, an XML server platform that became an Apache
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KW
3012Foundation project. He was a frequent speaker in the early days at
3013OSCON, and most recently at YAPC::NA in Madison. He was frequently on
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3014irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
3015group responsible for YAPC::NA Asheville in 2011.
a049258c 3016
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3017Kip and his constant contributions to the community will be greatly
3018missed.
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3019
3020=head1 Acknowledgements
2e0dcc12 3021
0cc8c746 3022Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 3023and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
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3024authors.
3025
3026Excluding auto-generated files, documentation and release tools, there were
3027approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
3028
3029Perl continues to flourish into its third decade thanks to a vibrant community
95b17558 3030of users and developers. The following people are known to have contributed the
ad543fb2 3031improvements that became Perl 5.26.0:
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3032
3033Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
3034König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
3035Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
3036Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
3037Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
3038Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3039Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3040Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3041D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3042Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3043De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3044Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3045Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3046Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3047Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3048Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3049Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3050Yves Orton, Zefram.
0cc8c746
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3051
3052The list above is almost certainly incomplete as it is automatically generated
95b17558 3053from version control history. In particular, it does not include the names of
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3054the (very much appreciated) contributors who reported issues to the Perl bug
3055tracker.
3056
3057Many of the changes included in this version originated in the CPAN modules
95b17558 3058included in Perl's core. We're grateful to the entire CPAN community for
0cc8c746
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3059helping Perl to flourish.
3060
3061For a more complete list of all of Perl's historical contributors, please see
3062the F<AUTHORS> file in the Perl source distribution.
f5b73711 3063
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3064=head1 Reporting Bugs
3065
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3066If you find what you think is a bug, you might check the articles recently
3067posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3068L<https://rt.perl.org/> . There may also be information at
4b8803f0 3069L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3070
e08634c5
SH
3071If you believe you have an unreported bug, please run the L<perlbug> program
3072included with your release. Be sure to trim your bug down to a tiny but
3073sufficient test case. Your bug report, along with the output of C<perl -V>,
7c825fca 3074will be sent off to C<perlbug@perl.org> to be analysed by the Perl porting team.
44691e6f 3075
87c118b9
DM
3076If the bug you are reporting has security implications which make it
3077inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3078L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3079for details of how to report the issue.
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3080
3081=head1 SEE ALSO
3082
e08634c5
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3083The F<Changes> file for an explanation of how to view exhaustive details on
3084what changed.
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3085
3086The F<INSTALL> file for how to build Perl.
3087
3088The F<README> file for general stuff.
3089
3090The F<Artistic> and F<Copying> files for copyright information.
3091
3092=cut