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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
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362This is used for debugging of code within PerlIO to avoid recursive
363calls. Previously this output would be sent to the file specified
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364by the C<PERLIO_DEBUG> environment variable if perl wasn't running
365setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
366
367If perl performed output at a point where it hadn't yet parsed its
368switches this could result in perl creating or overwriting the file
369named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
370
371Perl now requires the C<-Di> switch to produce PerlIO debugging
372output. By default this is written to C<stderr>, but can optionally
373be redirected to a file by setting the C<PERLIO_DEBUG> environment
374variable.
a049258c 375
3ee934f7 376If perl is running setuid or the C<-T> switch was supplied,
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377C<PERLIO_DEBUG> is ignored and the debugging output is sent to
378C<stderr> as for any other C<-D> switch.
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379
380=head1 Incompatible Changes
381
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382=head2 Unescaped literal C<"{"> characters in regular expression
383patterns are no longer permissible
a049258c 384
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385You have to now say something like C<"\{"> or C<"[{]"> to specify to
386match a LEFT CURLY BRACKET; otherwise it is a fatal pattern compilation
387error. This change will allow future extensions to the language.
388
389These have been deprecated since v5.16, with a deprecation message
390raised for some uses starting in v5.22. Unfortunately, the code added
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391to raise the message was buggy, and failed to warn in some cases where
392it should have. Therefore, enforcement of this ban for these cases is
393deferred until Perl 5.30, but the code has been fixed to raise a
394default-on deprecation message for them in the meantime.
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395
396Some uses of literal C<"{"> occur in contexts where we do not foresee
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397the meaning ever being anything but the literal, such as the very first
398character in the pattern, or after a C<"|"> meaning alternation. Thus
399
400 qr/{fee|{fie/
401
402matches either of the strings C<{fee> or C<{fie>. To avoid forcing
403unnecessary code changes, these uses do not need to be escaped, and no
404warning is raised about them, and there are no current plans to change this.
405
406But it is always correct to escape C<"{">, and the simple rule to
407remember is to always do so.
a049258c 408
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409See L<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>>.
410
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411=head2 C<scalar(%hash)> return signature changed
412
413The value returned for C<scalar(%hash)> will no longer show information about
414the buckets allocated in the hash. It will simply return the count of used
415keys. It is thus equivalent to C<0+keys(%hash)>.
416
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417A form of backwards compatibility is provided via
418L<C<Hash::Util::bucket_ratio()>|Hash::Util/bucket_ratio> which provides
419the same behavior as
420C<scalar(%hash)> provided in Perl 5.24 and earlier.
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421
422=head2 C<keys> returned from an lvalue subroutine
423
424C<keys> returned from an lvalue subroutine can no longer be assigned
425to in list context.
426
427 sub foo : lvalue { keys(%INC) }
428 (foo) = 3; # death
429 sub bar : lvalue { keys(@_) }
430 (bar) = 3; # also an error
431
432This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
433C<(keys @_) = ...>, which are also errors. [perl #128187]
a049258c 434
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435=head2 C<${^ENCODING}> has been removed
436
437Consequently, the L<encoding> pragma's default mode is no longer supported. If
438you still need to write your source code in encodings other than UTF-8, use a
439source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
440option.
441
0f032fe1 442=head2 C<POSIX::tmpnam()> has been removed
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443
444The fundamentally unsafe C<tmpnam()> interface was deprecated in
53799a91 445Perl 5.22 and has now been removed. In its place you can use,
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446for example, the L<File::Temp> interfaces.
447
448=head2 require ::Foo::Bar is now illegal.
449
95b17558 450Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
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451bareword require which starts with a double colon dies instead.
452
453=head2 Literal control character variable names are no longer permissible
454
455A variable name may no longer contain a literal control character under
456any circumstances. These previously were allowed in single-character
457names on ASCII platforms, but have been deprecated there since Perl
4585.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
459control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
460source code.
461
462=head2 C<NBSP> is no longer permissible in C<\N{...}>
463
464The name of a character may no longer contain non-breaking spaces. It
53799a91 465has been deprecated to do so since Perl 5.22.
8d25d2f3 466
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467=head1 Deprecations
468
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469=head2 String delimiters that aren't stand-alone graphemes are now deprecated
470
471In order for Perl to eventually allow string delimiters to be Unicode
472grapheme clusters (which look like a single character, but may be
0f275d26 473a sequence of several ones), we have to stop allowing a single character
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474delimiter that isn't a grapheme by itself. These are unlikely to exist
475in actual code, as they would typically display as attached to the
476character in front of them.
477
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478=head2 C<\cI<X>> that maps to a printable is no longer deprecated
479
480This means we have no plans to remove this feature. It still raises a
481warning, but only if syntax warnings are enabled. The feature was
482originally intended to be a way to express non-printable characters that
483don't have a mnemonic (C<\t> and C<\n> are mnemonics for two
484non-printable characters, but most non-printables don't have a
485mnemonic.) But the feature can be used to specify a few printable
486characters, though those are more clearly expressed as the printable
487itself. See
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488L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>.
489
2c8edc25 490=head1 Performance Enhancements
a049258c 491
2c8edc25 492=over 4
a049258c 493
2c8edc25 494=item *
a049258c 495
fce64130 496A hash in boolean context is now sometimes faster, I<e.g.>
a049258c 497
2c8edc25 498 if (!%h) { ... }
a049258c 499
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500This was already special-cased, but some cases were missed (such as
501C<grep %$_, @AoH>, and even the ones which weren't have been improved.
a049258c 502
2c8edc25 503=item * New Faster Hash Function on 64 bit builds
a049258c 504
95b17558 505We use a different hash function for short and long keys. This should
2c8edc25 506improve performance and security, especially for long keys.
a049258c 507
2c8edc25 508=item * readline is faster
a049258c 509
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510Reading from a file line-by-line with C<readline()> or C<< E<lt>E<gt> >> should
511now typically be faster due to a better implementation of the code that
512searches for the next newline character.
513
514=item *
a049258c 515
0f032fe1 516Reduce cost of C<SvVALID()>.
a049258c 517
2c8edc25 518=item *
ad5c8857 519
2c8edc25 520C<$ref1 = $ref2> has been optimized.
5e50eae4 521
4b99a68c 522=item *
f4b40f11 523
fce64130 524Array and hash assignment are now faster, I<e.g.>
ec34c8a4 525
2c8edc25
S
526 (..., @a) = (...);
527 (..., %h) = (...);
f4b40f11 528
2c8edc25 529especially when the RHS is empty.
ec34c8a4 530
2c8edc25 531=item *
a049258c 532
2c8edc25 533Reduce the number of odd special cases for the C<SvSCREAM> flag.
e770df11 534
2c8edc25 535=item *
a049258c 536
0f032fe1 537Avoid C<sv_catpvn()> in C<do_vop()> when unneeded.
2c8edc25
S
538
539=item *
540
541Enhancements in Regex concat COW implementation.
542
543=item *
544
8928e7db
DM
545Better optimise array and hash assignment: where an array or hash appears
546in the LHS of a list assignment, such as C<(..., @a) = (...);>, it's
547likely to be considerably faster, especially if it involves emptying the
548array/hash. For example this code runs about 1/3 faster compared to
d3972b39 549Perl 5.24.0:
d053832c
AB
550
551 my @a;
8928e7db 552 for my $i (1..10_000_000) {
d053832c
AB
553 @a = (1,2,3);
554 @a = ();
555 }
556
2c8edc25
S
557
558=item *
559
560Converting a single-digit string to a number is now substantially faster.
561
562=item *
563
564The internal op implementing the C<split> builtin has been simplified and
95b17558
KW
565sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
566to do its work. Secondly, code of the form C<my @x = split(...)> is now
2c8edc25
S
567optimised in the same way as C<@x = split(...)>, and is therefore a few
568percent faster.
569
570=item *
571
572The rather slow implementation for the experimental subroutine signatures
573feature has been made much faster; it is now comparable in speed with the
574old-style C<my ($a, $b, @c) = @_>.
7ca0bfc4 575
fbe3f407
S
576=item *
577
2c8edc25 578Bareword constant strings are now permitted to take part in constant
95b17558 579folding. They were originally exempted from constant folding in August 1999,
2c8edc25 580during the development of Perl 5.6, to ensure that C<use strict "subs">
95b17558 581would still apply to bareword constants. That has now been accomplished a
2c8edc25
S
582different way, so barewords, like other constants, now gain the performance
583benefits of constant folding.
584
585This also means that void-context warnings on constant expressions of
586barewords now report the folded constant operand, rather than the operation;
587this matches the behaviour for non-bareword constants.
a049258c
S
588
589=back
590
2c8edc25
S
591=head1 Modules and Pragmata
592
a049258c
S
593=head2 Updated Modules and Pragmata
594
595=over 4
fbe3f407 596
759020c9 597=item *
7ca0bfc4 598
0cc8c746
S
599L<Archive::Tar> has been upgraded from version 2.04 to 2.24.
600
601=item *
602
603L<arybase> has been upgraded from version 0.11 to 0.12.
604
605=item *
606
607L<attributes> has been upgraded from version 0.27 to 0.29.
a049258c 608
2c8edc25 609The deprecation message for the C<:unique> and C<:locked> attributes
0f275d26 610now mention that they will disappear in Perl 5.28.
a049258c 611
2c8edc25 612=item *
a049258c 613
0cc8c746
S
614L<B> has been upgraded from version 1.62 to 1.68.
615
616=item *
617
618L<B::Concise> has been upgraded from version 0.996 to 0.999.
2c8edc25
S
619
620Its output is now more descriptive for C<op_private> flags.
d5c7a4fc 621
759020c9
S
622=item *
623
0cc8c746
S
624L<B::Debug> has been upgraded from version 1.23 to 1.24.
625
626=item *
627
628L<B::Deparse> has been upgraded from version 1.37 to 1.40.
629
630=item *
631
2c8edc25 632L<B::Xref> has been upgraded from version 1.05 to 1.06.
a049258c 633
2c8edc25 634It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 635
2c8edc25 636=item *
a049258c 637
0cc8c746
S
638L<base> has been upgraded from version 2.23 to 2.25.
639
640=item *
641
642L<bignum> has been upgraded from version 0.42 to 0.47.
643
644=item *
645
646L<Carp> has been upgraded from version 1.40 to 1.42.
647
648=item *
649
650L<charnames> has been upgraded from version 1.43 to 1.44.
651
652=item *
653
654L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.074.
655
656=item *
657
658L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.074.
659
660=item *
661
662L<Config::Perl::V> has been upgraded from version 0.25 to 0.28.
663
664=item *
665
666L<CPAN> has been upgraded from version 2.11 to 2.18.
667
668=item *
669
670L<CPAN::Meta> has been upgraded from version 2.150005 to 2.150010.
671
672=item *
673
674L<Data::Dumper> has been upgraded from version 2.160 to 2.167.
a049258c 675
2c8edc25 676The XS implementation now supports Deparse.
a049258c 677
2c8edc25 678This fixes a stack management bug. [perl #130487].
a049258c 679
2c8edc25 680=item *
a049258c 681
0cc8c746
S
682L<DB_File> has been upgraded from version 1.835 to 1.840.
683
684=item *
685
686L<Devel::Peek> has been upgraded from version 1.23 to 1.26.
687
688=item *
689
690L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
691
692=item *
693
2c8edc25 694L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
a049258c 695
2c8edc25 696It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 697
2c8edc25 698=item *
a049258c 699
0cc8c746 700L<diagnostics> has been upgraded from version 1.34 to 1.36.
a049258c 701
2c8edc25 702It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
7ca0bfc4 703
ad5c8857 704=item *
7ca0bfc4 705
0cc8c746
S
706L<Digest> has been upgraded from version 1.17 to 1.17_01.
707
708=item *
709
710L<Digest::MD5> has been upgraded from version 2.54 to 2.55.
711
712=item *
713
714L<Digest::SHA> has been upgraded from version 5.95 to 5.96.
715
716=item *
717
718L<DynaLoader> has been upgraded from version 1.38 to 1.42.
719
720=item *
721
722L<Encode> has been upgraded from version 2.80 to 2.88.
723
724=item *
725
726L<encoding> has been upgraded from version 2.17 to 2.19.
8f7edc68 727
ee8180b8 728This module's default mode is no longer supported. It now
2c8edc25 729dies when imported, unless the C<Filter> option is being used.
d5c7a4fc 730
2c8edc25 731=item *
d5c7a4fc 732
2c8edc25 733L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
a049258c 734
ee8180b8 735This module is no longer supported. It emits a warning to
2c8edc25 736that effect and then does nothing.
a049258c 737
2c8edc25 738=item *
d5c7a4fc 739
0cc8c746 740L<Errno> has been upgraded from version 1.25 to 1.28.
a049258c 741
2c8edc25 742Document that using C<%!> loads Errno for you.
d5c7a4fc 743
2c8edc25 744It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
3abe9611 745
c714fb1f 746=item *
3ce6a296 747
2c8edc25 748L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
a049258c 749
2c8edc25 750It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 751
2c8edc25 752=item *
a049258c 753
0cc8c746
S
754L<ExtUtils::MakeMaker> has been upgraded from version 7.10_01 to 7.24.
755
756=item *
757
758L<ExtUtils::Miniperl> has been upgraded from version 1.05 to 1.06.
759
760=item *
761
762L<ExtUtils::ParseXS> has been upgraded from version 3.31 to 3.34.
763
764=item *
765
766L<ExtUtils::Typemaps> has been upgraded from version 3.31 to 3.34.
767
768=item *
769
770L<feature> has been upgraded from version 1.42 to 1.47.
2c8edc25
S
771
772Fixes the Unicode Bug in the range operator.
a049258c
S
773
774=item *
5c92a635 775
0cc8c746
S
776L<File::Copy> has been upgraded from version 2.31 to 2.32.
777
778=item *
779
780L<File::Fetch> has been upgraded from version 0.48 to 0.52.
781
782=item *
783
784L<File::Glob> has been upgraded from version 1.26 to 1.28.
d5c7a4fc 785
2c8edc25 786Issue a deprecation message for C<File::Glob::glob()>.
d5c7a4fc 787
2c8edc25 788=item *
d5c7a4fc 789
0cc8c746
S
790L<File::Spec> has been upgraded from version 3.63 to 3.67.
791
792=item *
793
794L<FileHandle> has been upgraded from version 2.02 to 2.03.
795
796=item *
797
2c8edc25 798L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
a049258c 799
2c8edc25
S
800It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
801end-of-file. [perl #107726]
64afbd29
DM
802
803=item *
804
0cc8c746
S
805L<Getopt::Long> has been upgraded from version 2.48 to 2.49.
806
807=item *
808
809L<Getopt::Std> has been upgraded from version 1.11 to 1.12.
810
811=item *
812
813L<Hash::Util> has been upgraded from version 0.19 to 0.22.
814
815=item *
816
817L<HTTP::Tiny> has been upgraded from version 0.056 to 0.070.
a049258c 818
2c8edc25 819Internal 599-series errors now include the redirect history.
a049258c 820
2c8edc25 821=item *
a049258c 822
0cc8c746 823L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
a049258c 824
2c8edc25 825It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 826
2c8edc25 827=item *
a049258c 828
0cc8c746
S
829L<IO> has been upgraded from version 1.36 to 1.38.
830
831=item *
832
601d9a87 833IO-Compress has been upgraded from version 2.069 to 2.074.
0cc8c746
S
834
835=item *
836
837L<IO::Socket::IP> has been upgraded from version 0.37 to 0.38.
838
839=item *
840
841L<IPC::Cmd> has been upgraded from version 0.92 to 0.96.
842
843=item *
844
845L<IPC::SysV> has been upgraded from version 2.06_01 to 2.07.
846
847=item *
848
849L<JSON::PP> has been upgraded from version 2.27300 to 2.27400_02.
850
851=item *
852
2c8edc25
S
853L<lib> has been upgraded from version 0.63 to 0.64.
854
855It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
faab9793 856
c714fb1f 857=item *
ad5c8857 858
0cc8c746
S
859L<List::Util> has been upgraded from version 1.42_02 to 1.46_02.
860
861=item *
862
863L<Locale::Codes> has been upgraded from version 3.37 to 3.42.
864
865=item *
866
867L<Locale::Maketext> has been upgraded from version 1.26 to 1.28.
868
869=item *
870
871L<Locale::Maketext::Simple> has been upgraded from version 0.21 to 0.21_01.
872
873=item *
874
875L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
ad5c8857 876
2c8edc25 877There have also been some core customizations.
ad5c8857 878
2c8edc25 879=item *
2e0dcc12 880
0cc8c746
S
881L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
882
883=item *
884
885L<Math::BigRat> has been upgraded from version 0.260802 to 0.2611.
886
887=item *
888
889L<Math::Complex> has been upgraded from version 1.59 to 1.5901.
890
891=item *
892
893L<Memoize> has been upgraded from version 1.03 to 1.03_01.
894
895=item *
896
897L<Module::CoreList> has been upgraded from version 5.20170420 to 5.20170520.
898
899=item *
900
901L<Module::Load::Conditional> has been upgraded from version 0.64 to 0.68.
902
903=item *
904
905L<Module::Metadata> has been upgraded from version 1.000031 to 1.000033.
906
907=item *
908
909L<mro> has been upgraded from version 1.18 to 1.20.
910
911=item *
912
913L<Net::Ping> has been upgraded from version 2.43 to 2.55.
d5c7a4fc 914
2c8edc25
S
915IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
916other enhancements.
d5c7a4fc 917
2c8edc25
S
918Remove sudo from 500_ping_icmp.t.
919
920Avoid stderr noise in tests
921
0f275d26 922Check for echo in new L<Net::Ping> tests.
d5c7a4fc 923
a049258c 924=item *
d5c7a4fc 925
0cc8c746
S
926L<NEXT> has been upgraded from version 0.65 to 0.67.
927
928=item *
929
930L<Opcode> has been upgraded from version 1.34 to 1.39.
931
932=item *
933
934L<open> has been upgraded from version 1.10 to 1.11.
935
936=item *
937
2c8edc25 938L<OS2::Process> has been upgraded from version 1.11 to 1.12.
a049258c 939
2c8edc25 940It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 941
2c8edc25 942=item *
a049258c 943
2c8edc25 944L<overload> has been upgraded from version 1.26 to 1.28.
a049258c 945
2c8edc25 946Its compilation speed has been improved slightly.
a049258c 947
2c8edc25
S
948=item *
949
0cc8c746
S
950L<parent> has been upgraded from version 0.234 to 0.236.
951
952=item *
953
2c8edc25
S
954L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
955
956Ignore F</dev/tty> on non-Unix systems. [perl #113960]
957
958=item *
959
0cc8c746
S
960L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
961
962=item *
963
964L<perlfaq> has been upgraded from version 5.021010 to 5.021011.
965
966=item *
967
968L<PerlIO> has been upgraded from version 1.09 to 1.10.
969
970=item *
971
972L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
973
974=item *
975
976L<PerlIO::scalar> has been upgraded from version 0.24 to 0.26.
977
978=item *
979
980L<Pod::Checker> has been upgraded from version 1.60 to 1.73.
981
982=item *
983
984L<Pod::Functions> has been upgraded from version 1.10 to 1.11.
985
986=item *
987
988L<Pod::Html> has been upgraded from version 1.22 to 1.2202.
989
990=item *
991
992L<Pod::Perldoc> has been upgraded from version 3.25_02 to 3.28.
993
994=item *
995
996L<Pod::Simple> has been upgraded from version 3.32 to 3.35.
997
998=item *
999
1000L<Pod::Usage> has been upgraded from version 1.68 to 1.69.
1001
1002=item *
1003
95b17558 1004L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
2c8edc25
S
1005defects in making its symbols exportable. [perl #127821]
1006The C<POSIX::tmpnam()> interface has been removed,
1007see L</"POSIX::tmpnam() has been removed">.
1008Trying to import POSIX subs that have no real implementations
1009(like C<POSIX::atend()>) now fails at import time, instead of
1010waiting until runtime.
1011
1012=item *
1013
0cc8c746 1014L<re> has been upgraded from version 0.32 to 0.34
2c8edc25
S
1015
1016This adds support for the new L<C<E<47>xx>|perlre/E<sol>x and E<sol>xx>
1017regular expression pattern modifier, and a change to the L<S<C<use re
1018'strict'>>|re/'strict' mode> experimental feature. When S<C<re
1019'strict'>> is enabled, a warning now will be generated for all
df48f9a4 1020unescaped uses of the two characters C<"}"> and C<"]"> in regular
2c8edc25 1021expression patterns (outside bracketed character classes) that are taken
df48f9a4 1022literally. This brings them more in line with the C<")"> character which
2c8edc25
S
1023is always a metacharacter unless escaped. Being a metacharacter only
1024sometimes, depending on action at a distance, can lead to silently
1025having the pattern mean something quite different than was intended,
1026which the S<C<re 'strict'>> mode is intended to minimize.
1027
1028=item *
1029
0cc8c746
S
1030L<Safe> has been upgraded from version 2.39 to 2.40.
1031
1032=item *
1033
1034L<Scalar::Util> has been upgraded from version 1.42_02 to 1.46_02.
1035
1036=item *
1037
1038L<Storable> has been upgraded from version 2.56 to 2.62.
2c8edc25
S
1039
1040Fixes [perl #130098].
1041
1042=item *
1043
0cc8c746
S
1044L<Symbol> has been upgraded from version 1.07 to 1.08.
1045
1046=item *
1047
1048L<Sys::Syslog> has been upgraded from version 0.33 to 0.35.
1049
1050=item *
1051
1052L<Term::ANSIColor> has been upgraded from version 4.04 to 4.06.
1053
1054=item *
1055
2c8edc25
S
1056L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
1057
1058It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1059
1060=item *
1061
0cc8c746 1062L<Test> has been upgraded from version 1.28 to 1.30.
2c8edc25
S
1063
1064It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1065
1066=item *
1067
0cc8c746
S
1068L<Test::Harness> has been upgraded from version 3.36 to 3.38.
1069
1070=item *
1071
1072L<Test::Simple> has been upgraded from version 1.001014 to 1.302073.
1073
1074=item *
1075
1076L<Thread::Queue> has been upgraded from version 3.09 to 3.12.
1077
1078=item *
1079
2c8edc25
S
1080L<Thread::Semaphore> has been upgraded from 2.12 to 2.13.
1081
1082Added the C<down_timed> method.
1083
1084=item *
1085
0cc8c746 1086L<threads> has been upgraded from version 2.07 to 2.15.
2c8edc25
S
1087
1088Compatibility with 5.8 has been restored.
1089
1090Fixes [perl #130469].
1091
1092=item *
1093
0cc8c746 1094L<threads::shared> has been upgraded from version 1.51 to 1.56.
2c8edc25
S
1095
1096This fixes [cpan #119529], [perl #130457]
1097
1098=item *
1099
0cc8c746
S
1100L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
1101
1102=item *
1103
1104L<Time::HiRes> has been upgraded from version 1.9733 to 1.9741.
2c8edc25
S
1105
1106It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
11073.9).
1108
1109Now uses C<clockid_t>.
1110
1111=item *
1112
0cc8c746
S
1113L<Time::Local> has been upgraded from version 1.2300 to 1.25.
1114
1115=item *
1116
1117L<Unicode::Collate> has been upgraded from version 1.14 to 1.19.
1118
1119=item *
1120
1121L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
2c8edc25
S
1122
1123It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1124
1125=item *
1126
0cc8c746
S
1127L<version> has been upgraded from version 0.9916 to 0.9917.
1128
1129=item *
1130
1131L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
2c8edc25
S
1132
1133It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1134
1135=item *
1136
0cc8c746
S
1137L<warnings> has been upgraded from version 1.36 to 1.37.
1138
1139=item *
1140
1141L<XS::Typemap> has been upgraded from version 0.14 to 0.15.
1142
1143=item *
1144
1145L<XSLoader> has been upgraded from version 0.21 to 0.27.
2c8edc25
S
1146
1147Fixed a security hole in which binary files could be loaded from a path
1148outside of L<C<@INC>|perlvar/@INC>.
1149
1150It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1151
1152=back
1153
2c8edc25
S
1154=head1 Documentation
1155
1156=head2 New Documentation
a049258c 1157
2c8edc25 1158=head3 L<perldeprecation>
a049258c 1159
2c8edc25 1160This file documents all upcoming deprecations, and some of the deprecations
95b17558 1161which already have been removed. The purpose of this documentation is
2c8edc25
S
1162two-fold: document what will disappear, and by which version, and serve
1163as a guide for people dealing with code which has features that no longer
1164work after an upgrade of their perl.
a049258c 1165
2c8edc25 1166=head2 Changes to Existing Documentation
a049258c 1167
b10de59c
KW
1168We have attempted to update the documentation to reflect the changes
1169listed in this document. If you find any we have missed, send email to
bfe8fcbb 1170L<perlbug@perl.org|mailto:perlbug@perl.org>.
a049258c 1171
b10de59c
KW
1172Additionally all references to Usenet have been removed, and the
1173following selected changes have been made:
2c8edc25 1174
b10de59c 1175=head3 L<perlfunc>
a049258c 1176
b10de59c 1177=over 4
a049258c 1178
2c8edc25
S
1179=item *
1180
b10de59c
KW
1181Removed obsolete text about L<C<defined()>|perlfunc/defined>
1182on aggregates that should have been deleted earlier, when the feature
1183was removed.
2c8edc25
S
1184
1185=item *
1186
b10de59c
KW
1187Corrected documentation of L<C<eval()>|perlfunc/eval>,
1188and L<C<evalbytes()>|perlfunc/evalbytes>.
a049258c 1189
2c8edc25 1190=item *
a049258c 1191
b10de59c
KW
1192Clarified documentation of L<C<seek()>|perlfunc/seek>,
1193L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>
f9b6dffc 1194emphasizing that positions are in bytes and not characters.
b10de59c 1195L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
2c8edc25
S
1196
1197=item *
1198
b10de59c
KW
1199Clarified documentation of L<C<sort()>|perlfunc/sort LIST> concerning
1200the variables C<$a> and C<$b>.
2c8edc25
S
1201
1202=item *
a049258c 1203
de7be789
KW
1204In L<C<split()>|perlfunc/split> noted that certain pattern modifiers are
1205legal, and added a caution about its use in Perls before v5.11,
a049258c 1206
2c8edc25 1207=item *
a049258c 1208
b10de59c
KW
1209Removed obsolete documentation of L<C<study()>|perlfunc/study>, noting
1210that it is now a no-op.
2c8edc25
S
1211
1212=item *
1213
b10de59c
KW
1214Noted that L<C<vec()>|perlfunc/vec> doesn't work well when the string
1215contains characters whose code points are above 255.
a049258c 1216
2c8edc25 1217=back
a049258c 1218
b10de59c 1219=head3 L<perlguts>
a049258c
S
1220
1221=over 4
1222
1223=item *
1224
b10de59c
KW
1225Added advice on
1226L<formatted printing of operands of C<Size_t> and C<SSize_t>|perlguts/Formatted Printing of Size_t and SSize_t>
a049258c
S
1227
1228=back
1229
b10de59c 1230=head3 L<perlhack>
2c8edc25
S
1231
1232=over 4
1233
1234=item *
1235
7964b3a0
KW
1236Clarify what editor tab stop rules to use, and note that we are
1237migrating away from using tabs, replacing them with sequences of SPACE
1238characters.
2c8edc25
S
1239
1240=back
a049258c 1241
b10de59c 1242=head3 L<perlhacktips>
a049258c
S
1243
1244=over 4
1245
1246=item *
1247
b10de59c 1248Give another reason to use C<cBOOL> to cast an expression to boolean.
2c8edc25
S
1249
1250=item *
1251
b10de59c
KW
1252Note that there are macros C<TRUE> and C<FALSE> available to express
1253boolean values.
a049258c 1254
2c8edc25 1255=back
a049258c 1256
2c8edc25 1257=head3 L<perlinterp>
a049258c
S
1258
1259=over 4
1260
1261=item *
1262
2c8edc25
S
1263L<perlinterp> has been expanded to give a more detailed example of how to
1264hunt around in the parser for how a given operator is handled.
a049258c
S
1265
1266=back
1267
2c8edc25 1268=head3 L<perllocale>
a049258c
S
1269
1270=over 4
1271
a6733086
S
1272=item *
1273
b10de59c
KW
1274Some locales aren't compatible with Perl. Note that these can cause
1275core dumps.
a049258c
S
1276
1277=back
1278
2c8edc25
S
1279=head3 L<perlmodinstall>
1280
1281=over 4
1282
1283=item *
1284
b10de59c 1285Various clarifications have been added.
2c8edc25
S
1286
1287=back
1288
1289=head3 L<perlmodlib>
1290
1291=over 4
1292
1293=item *
1294
b10de59c 1295Updated the site mirror list.
2c8edc25
S
1296
1297=back
1298
1299=head3 L<perlobj>
1300
1301=over 4
1302
1303=item *
1304
1305Added a section on calling methods using their fully qualified names.
1306
1307=item *
1308
0f032fe1 1309Do not discourage manual C<@ISA>.
2c8edc25
S
1310
1311=back
1312
1313=head3 L<perlootut>
1314
1315=over 4
1316
1317=item *
1318
2c8edc25
S
1319Mention C<Moo> more.
1320
1321=back
1322
1323=head3 L<perlop>
1324
1325=over 4
1326
1327=item *
1328
b072a8ef
KW
1329Note that white space must be used for quoting operators if the
1330delimiter is a word character (I<i.e.>, matches C<\w>).
1331
1332=item *
1333
1334Clarify that in regular expression patterns delimited by single quotes,
1335no variable interpolation is done.
2c8edc25
S
1336
1337=back
1338
1339=head3 L<perlre>
1340
1341=over 4
1342
1343=item *
1344
1c34b59a
KW
1345The first part was extensively rewritten to incorporate various basic
1346points, that in earlier versions were mentioned in sort of an appendix
1347on Version 8 regular expressions.
1348
0cbd1ffa
KW
1349=item *
1350
b10de59c
KW
1351Note that it is common to have the C</x> modifier and forget that this
1352means that C<"#"> has to be escaped.
2c8edc25
S
1353
1354=back
1355
b10de59c 1356=head3 L<perlretut>
2c8edc25
S
1357
1358=over 4
1359
1360=item *
1361
b10de59c 1362Add introductory material
2c8edc25
S
1363
1364=item *
1365
b10de59c
KW
1366Note that a metacharacter occurring in a context where it can't mean
1367that, silently loses its meta-ness and matches literally.
1368L<C<use re 'strict'>|re/'strict' mode> can catch some of these.
2c8edc25
S
1369
1370=back
1371
1372=head3 L<perlunicode>
1373
1374=over 4
1375
1376=item *
1377
b10de59c 1378Corrected the text about Unicode BYTE ORDER MARK handling.
2c8edc25
S
1379
1380=item *
1381
1382Updated the text to correspond with changes in Unicode UTS#18, concerning
1383regular expressions, and Perl compatibility with what it says.
1384
1385=back
1386
1387=head3 L<perlvar>
1388
1389=over 4
1390
1391=item *
1392
95b17558 1393Document C<@ISA>. Was documented other places, not not in L<perlvar>.
2c8edc25
S
1394
1395=back
1396
1397=head1 Diagnostics
1398
1399=head2 New Diagnostics
1400
1401=head3 New Errors
1402
1403=over 4
1404
1405=item *
1406
df48f9a4 1407Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
2c8edc25
S
1408a warning recommending to fix the C<do> statement:
1409
1410L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
1411
1412=item *
1413
1414Using the empty pattern (which re-executes the last successfully-matched
1415pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
95b17558 1416always previously yielded a segfault. It now produces an error:
4f73c567 1417L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
2c8edc25
S
1418
1419=item *
1420
1421L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
1422
1423(F) To declare references to variables, as in C<my \%x>, you must first enable
1424the feature:
1425
1426 no warnings "experimental::declared_refs";
1427 use feature "declared_refs";
1428
1429=item *
1430
1431L<Version control conflict marker|perldiag/"Version control conflict marker">
1432
e6abae1c 1433(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
95b17558 1434C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
2c8edc25
S
1435version control system to mark conflicts after a failed merge operation.
1436
1437=item *
1438
1439L<%s: command not found|perldiag/"%s: command not found">
1440
1441(A) You've accidentally run your script through B<bash> or another shell
1442instead of Perl. Check the #! line, or manually feed your script into
1443Perl yourself. The #! line at the top of your file could look like:
1444
1445 #!/usr/bin/perl
1446
1447=item *
1448
1449L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1450
1451(A) You've accidentally run your script through B<zsh> or another shell
1452instead of Perl. Check the #! line, or manually feed your script into
1453Perl yourself. The #! line at the top of your file could look like:
1454
1455 #!/usr/bin/perl
1456
1457=item *
1458
a6733086 1459L<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 1460
d8362e1b
KW
1461Unescaped left braces are now illegal in some contexts in regular expression
1462patterns. In other contexts, they are still just deprecated; they will
1463be illegal in Perl 5.30.
2c8edc25
S
1464
1465=item *
1466
1467L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1468
1469=item *
1470
1471L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1472
1473=item *
1474
1475L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1476
1477=item *
1478
1479L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1480
1481=back
1482
1483=head3 New Warnings
1484
1485=over 4
1486
1487=item *
1488
4f73c567 1489L<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
1490
1491See L</Deprecations>
1492
1493=item *
1494
1495L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1496
1497(S experimental::declared_refs) This warning is emitted if you use a reference
1498constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1499C<local()>. Simply suppress the warning if you want to use the feature, but
1500know that in doing so you are taking the risk of using an experimental feature
1501which may change or be removed in a future Perl version:
1502
1503 no warnings "experimental::declared_refs";
1504 use feature "declared_refs";
1505 $fooref = my \$foo;
1506
1507=item *
1508
4f73c567 1509L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25 1510
0f275d26 1511The special variable C<${^ENCODING}>, formerly used to implement
53799a91 1512the C<encoding> pragma, is no longer supported as of Perl 5.26.
2c8edc25 1513
89853d76
DH
1514=item *
1515
df48f9a4 1516Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
89853d76
DH
1517a warning recommending to fix the C<do> statement:
1518
fc902710 1519L<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 1520
2c8edc25
S
1521=back
1522
1523=head2 Changes to Existing Diagnostics
1524
1525=over 4
1526
1527=item *
1528
1529When a C<require> fails, we now do not provide C<@INC> when the C<require>
1530is for a file instead of a module.
1531
1532=item *
1533
1534When C<@INC> is not scanned for a C<require> call, we no longer display
1535C<@INC> to avoid confusion.
1536
1537=item *
1538
1539Attribute "locked" is deprecated, and will disappear in Perl 5.28
1540
1541=item *
1542
1543Attribute "unique" is deprecated, and will disappear in Perl 5.28
1544
1545=item *
1546
1547Constants from lexical variables potentially modified elsewhere are
1548deprecated. This will not be allowed in Perl 5.32
1549
1550=item *
1551
0f032fe1 1552Deprecated use of C<my()> in false conditional. This will be a fatal error
2c8edc25
S
1553in Perl 5.30
1554
1555=item *
1556
0f032fe1 1557C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available
2c8edc25
S
1558in Perl 5.30
1559
1560=item *
1561
1562${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
1563
1564=item *
1565
1566File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
1567instead.
1568
1569=item *
1570
1571%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
1572
1573=item *
1574
1575$* is no longer supported. Its use will be fatal in Perl 5.30
1576
1577=item *
1578
1579$* is no longer supported. Its use will be fatal in Perl 5.30
1580
1581=item *
1582
1583Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1584
1585=item *
1586
1587Opening filehandle %s also as a directory. This will be a fatal
1588error in Perl 5.28
1589
1590=item *
1591
0f032fe1 1592Setting C<$/> to a reference to %s as a form of slurp is deprecated,
2c8edc25
S
1593treating as undef. This will be fatal in Perl 5.28
1594
1595=item *
1596
1597Unescaped left brace in regex is deprecated here (and will be fatal
1598in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
1599
1600=item *
1601
1602Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1603
1604=item *
1605
1606Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1607
1608=item *
1609
1610Use of code point 0x%s is deprecated; the permissible max is 0x%s.
1611This will be fatal in Perl 5.28
1612
1613=item *
1614
1615Use of comma-less variable list is deprecated. Its use will be fatal
1616in Perl 5.28
1617
1618=item *
1619
1620Use of inherited AUTOLOAD for non-method %s() is deprecated. This
1621will be fatal in Perl 5.28
1622
1623=item *
1624
1625Use of strings with code points over 0xFF as arguments to %s operator
1626is deprecated. This will be a fatal error in Perl 5.28
1627
1628=item *
1629
0f032fe1 1630Improve error for missing C<tie()> package/method. This brings the error messages
2c8edc25
S
1631in line with the ones used for normal method calls, despite not using
1632call_method().
1633
1634=item *
1635
0f032fe1
KW
1636Make the C<sysread()>/C<syswrite()> I<etc.>, C<:utf8> handle warnings
1637XXX default. These warnings were under 'deprecated' previously.
2c8edc25
S
1638
1639=item *
1640
0f032fe1 1641C<do> errors now refer to C<do> (not C<require>).
2c8edc25
S
1642
1643=item *
1644
1645Details as to the exact problem have been added to the diagnostics that
1646occur when malformed UTF-8 is encountered when trying to convert to a
1647code point.
1648
1649=item *
1650
1651Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
1652blames the variable for an uninitialized-value warning encountered by the
1653tied/magical code.
1654
1655=item *
1656
2c8edc25
S
1657Code like C<$x = $x . "a"> was incorrectly failing to yield a
1658L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
1659warning when C<$x> was a lexical variable with an undefined value. That has
1660now been fixed. [perl #127877]
1661
1662=item *
1663
1664When the error "Experimental push on scalar is now forbidden" is raised for
1665the hash functions C<keys>, C<each>, and C<values>, it is now followed by
1666the more helpful message, "Type of arg 1 to whatever must be hash or
1667array". [perl #127976]
1668
1669=item *
1670
1671C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
53799a91 1672argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
2c8edc25
S
1673been fixed.
1674
1675=item *
1676
1677C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
1678string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
1679bringing it into consistency with C<$$scalar>.
1680
1681=item *
1682
1683C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
1684do, but merely produce a syntax error. [perl #128171]
1685
1686=item *
1687
1688C<do> or C<require> with a reference or typeglob which, when stringified,
53799a91 1689contains a null character started crashing in Perl 5.20, but has now been
2c8edc25
S
1690fixed. [perl #128182]
1691
1692=back
1693
1694=head1 Utility Changes
1695
1696=head2 F<c2ph> and F<pstruct>
1697
1698=over 4
1699
1700=item *
1701
1702These old utilities have long since superceded by L<h2xs>, and are
1703now gone from the distribution.
1704
1705=back
1706
1707=head2 F<Porting/pod_lib.pl>
1708
1709=over 4
1710
1711=item *
1712
1713Removed spurious executable bit.
1714
1715=item *
1716
fb5d4b1a 1717Account for the possibility of DOS file endings.
2c8edc25
S
1718
1719=back
1720
1721=head2 F<Porting/sync-with-cpan>
1722
1723=over 4
1724
1725=item *
1726
1727Many improvements
1728
1729=back
1730
1731=head2 F<perf/benchmarks>
1732
1733=over 4
1734
1735=item *
1736
1737Tidy file, rename some symbols.
1738
1739=back
1740
1741=head2 F<Porting/checkAUTHORS.pl>
1742
1743=over 4
1744
1745=item *
1746
0f275d26 1747Replace obscure character range with C<\w>.
2c8edc25
S
1748
1749=back
1750
1751=head2 F<t/porting/regen.t>
1752
1753=over 4
1754
1755=item *
1756
1757try to be more helpful when tests fail.
1758
1759=back
1760
1761=head2 F<utils/h2xs.PL>
1762
1763=over 4
1764
1765=item *
1766
1767Avoid infinite loop for enums.
1768
1769=back
1770
1771=head2 L<perlbug>
1772
1773=over 4
1774
1775=item *
1776
1777Long lines in the message body are now wrapped at 900 characters, to stay
1778well within the 1000-character limit imposed by SMTP mail transfer agents.
1779This is particularly likely to be important for the list of arguments to
1780C<Configure>, which can readily exceed the limit if, for example, it names
95b17558 1781several non-default installation paths. This change also adds the first unit
2c8edc25
S
1782tests for perlbug. [perl #128020]
1783
1784=back
1785
1786=head1 Configuration and Compilation
1787
1788=over 4
1789
1790=item *
1791
89853d76 1792C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1793
1794=item *
1795
18618fea 1796The C<dtrace> build process has further changes [perl #130108]:
2c8edc25
S
1797
1798=over
1799
1800=item *
1801
1802If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1803built within a FreeBSD jail.
1804
1805=item *
1806
1807On systems that build a dtrace object file (FreeBSD, Solaris and
1808SystemTap's dtrace emulation), copy the input objects to a separate
1809directory and process them there, and use those objects in the link,
1810since C<dtrace -G> also modifies these objects.
1811
1812=item *
1813
1814Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1815to libelf symbols.
1816
1817=item *
1818
1819Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1820default build on Solaris generates probes from the unused inline
1821functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1822fail.
1823
1824=back
1825
2c8edc25
S
1826=item *
1827
0f032fe1
KW
1828You can now disable perl's use of the C<PERL_HASH_SEED> and
1829C<PERL_PERTURB_KEYS> environment variables by configuring perl with
2c8edc25
S
1830C<-Accflags=NO_PERL_HASH_ENV>.
1831
1832=item *
1833
0f032fe1 1834You can now disable perl's use of the C<PERL_HASH_SEED_DEBUG> environment
2c8edc25
S
1835variable by configuring perl with
1836C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1837
1838=item *
1839
1840Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1841and C<Inf> to make builds more reproducible. [perl #130133]
1842
1843=item *
1844
fb5d4b1a 1845Since v5.18 for testing purposes, we have included support for
2c8edc25 1846building perl with a variety of non-standard, and non-recommended
95b17558
KW
1847hash functions. Since we do not recommend the use of these functions
1848we have removed them and their corresponding build options. Specifically
2c8edc25
S
1849this includes the following build options:
1850
1851 PERL_HASH_FUNC_SDBM
1852 PERL_HASH_FUNC_DJB2
1853 PERL_HASH_FUNC_SUPERFAST
1854 PERL_HASH_FUNC_MURMUR3
1855 PERL_HASH_FUNC_ONE_AT_A_TIME
1856 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1857 PERL_HASH_FUNC_MURMUR_HASH_64A
1858 PERL_HASH_FUNC_MURMUR_HASH_64B
1859
1860=item *
1861
1862Remove "Warning: perl appears in your path"
1863
1864This install warning is more or less obsolete, since most platforms already
0f032fe1 1865B<will> have a F</usr/bin/perl> or similar provided by the OS.
2c8edc25
S
1866
1867=item *
1868
0f032fe1 1869Reduce verbosity of C<make install.man>
2c8edc25
S
1870
1871Previously, two progress messages were emitted for each manpage: one by
1872installman itself, and one by the function in install_lib.pl that it calls to
95b17558 1873actually install the file. Disabling the second of those in each case saves
2c8edc25
S
1874over 750 lines of unhelpful output.
1875
1876=item *
1877
0f032fe1 1878Cleanup for C<clang -Weverything> support. [perl 129961]
2c8edc25
S
1879
1880=item *
1881
1882Configure: signbit scan was assuming too much, stop assuming negative 0.
1883
1884=item *
1885
1886Various compiler warnings have been silenced.
1887
1888=item *
1889
1890Several smaller changes have been made to remove impediments to compiling under
1891C++11.
1892
1893=item *
1894
1895Builds using C<USE_PAD_RESET> now work again; this configuration had
1896bit-rotted.
1897
1898=item *
1899
1900A probe for C<gai_strerror> was added to F<Configure> that checks if the
0f032fe1
KW
1901the C<gai_strerror()> routine is available and can be used to
1902translate error codes returned by C<getaddrinfo()> into human
2c8edc25
S
1903readable strings.
1904
1905=item *
1906
0f032fe1 1907F<Configure> now aborts if both C<-Duselongdouble> and C<-Dusequadmath> are
2c8edc25
S
1908requested.
1909L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1910
1911=item *
1912
0f032fe1 1913Fixed a bug in which F<Configure> could append C<-quadmath> to the archname even
2c8edc25
S
1914if it was already present.
1915L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1916
1917=item *
1918
0f032fe1
KW
1919Clang builds with C<-DPERL_GLOBAL_STRUCT> or
1920C<-DPERL_GLOBAL_STRUCT_PRIVATE> have
2c8edc25
S
1921been fixed (by disabling Thread Safety Analysis for these configurations).
1922
1923=item *
1924
1925F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
1926files require updates. This could cause dependencies, F<perlmain.c>
1927in particular, to be rebuilt unnecessarily. [perl #126710]
1928
1929=item *
1930
1931The output of C<perl -V> has been reformatted so that each configuration
1932and compile-time option is now listed one per line, to improve
1933readability.
1934
1935=item *
1936
1937C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
1938invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
1939This means you can supply your target platform C<config.sh>, generate
1940the headers and proceed to build your cross-target perl. [perl #127234]
1941
1942=item *
1943
1944Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
1945counts when the environment variable C<PERL_TRACE_OPS> to be set to a
1946non-zero integer. This allows C<make test> to pass on such a build.
1947
1948=item *
1949
1950When building with GCC 6 and link-time optimization (the C<-flto> option to
1951C<gcc>), C<Configure> was treating all probed symbols as present on the
95b17558 1952system, regardless of whether they actually exist. This has been fixed.
2c8edc25
S
1953[perl #128131]
1954
1955=item *
1956
1957The F<t/test.pl> library is used for internal testing of Perl itself, and
95b17558 1958also copied by several CPAN modules. Some of those modules must work on
2c8edc25 1959older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
95b17558 1960features. Compatibility with Perl 5.8 was inadvertently removed some time
2c8edc25
S
1961ago; it has now been restored. [perl #128052]
1962
1963=item *
1964
1965The build process no longer emits an extra blank line before building each
1966"simple" extension (those with only F<*.pm> and F<*.pod> files).
1967
1968=back
1969
1970=head1 Testing
1971
dd84ba97
KW
1972Tests were added and changed to reflect the other additions and changes
1973in this release. In addition, these substantive changes were made:
1974
2c8edc25
S
1975=over 4
1976
1977=item *
1978
dd84ba97
KW
1979A new test script, F<comp/parser_run.t>, has been added to test
1980reads through invalid pointers.
2c8edc25
S
1981
1982=item *
1983
1984Tests for locales were erroneously using locales incompatible with Perl.
1985
1986=item *
1987
1988Some parts of the test suite that try to exhaustively test edge cases in the
1989regex implementation have been restricted to running for a maximum of five
95b17558 1990minutes. On slow systems they could otherwise take several hours, without
2c8edc25
S
1991significantly improving our understanding of the correctness of the code
1992under test.
1993
1994In addition, some of those test cases have been split into more files, to
1995allow them to be run in parallel on suitable systems.
1996
1997=item *
1998
1999A new internal facility allows analysing the time taken by the individual
2000tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
2001
2002=item *
2003
2004F<t/re/regexp_nonull.t> has been added to test that the regular expression
2005engine can handle scalars that do not have a null byte just past the end of
2006the string.
2007
2008=item *
2009
0ebc1fcf
KW
2010A new test script, F<t/op/decl-refs.t>, has been added to test the new feature
2011L</Declaring a reference to a variable>.
2c8edc25
S
2012
2013=item *
2014
dd84ba97
KW
2015A new test script, F<t/re/keep_tabs.t> has been added to contain tests
2016where C<\t> characters should not be expanded into spaces.
2017
2018=item *
2019
2c8edc25
S
2020A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
2021generated by bracketed character classes are as expected.
2022
2023=item *
2024
dd84ba97
KW
2025There is now more extensive testing of the Unicode-related API macros
2026and functions.
2027
2028=item *
2029
2030Several of the longer running API test files have been split into
2031multiple test files so that they can be run in parallel.
2032
2033=item *
2034
2c8edc25
S
2035F<t/harness> now tries really hard not to run tests outside of the Perl
2036source tree. [perl #124050]
2037
2038=back
2039
2040=head1 Platform Support
2041
2042=head2 New Platforms
2043
2044=over 4
2045
2046=item NetBSD/VAX
2047
2048Perl now compiles under NetBSD on VAX machines. However, it's not
2049possible for that platform to implement floating-point infinities and
2050NaNs compatibly with most modern systems, which implement the IEEE-754
2051floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2052literals, C<printf %a>) is not implemented, either.
2053The C<make test> passes 98% of tests.
2054
2055=over 4
2056
2057=item *
2058
2059Test fixes and minor updates.
2060
2061=item *
2062
2063Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2064
2065=back
2066
2067=back
2068
2069=head2 Platform-Specific Notes
2070
2071=over 4
2072
2073=item Darwin
2074
0f032fe1
KW
2075don't treat C<-Dprefix=/usr> as special, instead require an extra option
2076C<-Ddarwin_distribution> to produce the same results.
2c8edc25
S
2077
2078=item POSIX
2079
2080Finish removing POSIX deprecated functions.
2081
2082=item OS X
2083
0f032fe1
KW
2084OS X El Capitan doesn't implement the C<clock_gettime()> or
2085C<clock_getres()> APIs; emulate them as necessary.
2c8edc25
S
2086
2087=item macOS
2088
0f032fe1 2089Deprecated C<syscall(2)> on macOS 10.12.
2c8edc25
S
2090
2091=item EBCDIC
2092
2093Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2094
2095=item HP-UX
2096
2097L<Net::Ping> UDP test is skipped on HP-UX.
2098
2099=item Hurd
2100
2101The hints for Hurd have been improved enabling malloc wrap and reporting the
2102GNU libc used (previously it was an empty string when reported).
2103
2104=item VAX
2105
29ce4d71 2106VAX floating point formats are now supported on NetBSD.
2c8edc25
S
2107
2108=item VMS
2109
2110=over 4
2111
2112=item *
2113
2114The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
df48f9a4
KW
2115now a colon (C<":">) when running under a Unix shell. There is no change when
2116running under DCL (it's still C<"|">).
2c8edc25
S
2117
2118=item *
2119
29ce4d71
CB
2120C<configure.com> now recognizes the VSI-branded C compiler and no longer
2121recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
212215 or more years).
2c8edc25
S
2123
2124=back
2125
2126=item Windows
2127
2128=over 4
2129
2130=item *
2131
2132Support for compiling perl on Windows using Microsoft Visual Studio 2015
2133(containing Visual C++ 14.0) has been added.
2134
2135This version of VC++ includes a completely rewritten C run-time library, some
0f032fe1
KW
2136of the changes in which mean that work done to resolve a socket
2137C<close()> bug in
2c8edc25
S
2138perl #120091 and perl #118059 is not workable in its current state with this
2139version of VC++. Therefore, we have effectively reverted that bug fix for
2140VS2015 onwards on the basis that being able to build with VS2015 onwards is
2141more important than keeping the bug fix. We may revisit this in the future to
2142attempt to fix the bug again in a way that is compatible with VS2015.
2143
2144These changes do not affect compilation with GCC or with Visual Studio versions
fce64130 2145up to and including VS2013, I<i.e.>, the bug fix is retained (unchanged) for those
2c8edc25
S
2146compilers.
2147
2148Note that you may experience compatibility problems if you mix a perl built
2149with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2150perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2151Some incompatibility may arise because of the bug fix that has been reverted
2152for VS2015 builds of perl, but there may well be incompatibility anyway because
fce64130 2153of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
bdd37d82 2154L<http://stackoverflow.com/questions/30412951>).
2c8edc25
S
2155
2156=back
2157
2158=item Win32
2159
2160=over 4
2161
2162=item *
2163
95b17558 2164Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2c8edc25 2165depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
95b17558 2166the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2c8edc25
S
2167
2168=item *
2169
2170fp definitions have been updated.
2171
2172=back
2173
2c8edc25
S
2174=item Linux
2175
2176Drop support for Linux a.out Linux has used ELF for over twenty years.
2177
2178=item OpenBSD 6
2179
2180OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2181Make sure this is accounted for.
2182
2183=item FreeBSD
2184
0f032fe1 2185F<t/uni/overload.t>: Skip hanging test on FreeBSD.
2c8edc25
S
2186
2187=back
2188
2189=head1 Internal Changes
2190
2191=over 4
2192
2193=item *
2194
0ebc1fcf
KW
2195A new API function L<C<sv_setpv_bufsize()>|perlapi/sv_setpv_bufsize>
2196allows simultaneously setting the
c2ef64b1
DM
2197length and allocated size of the buffer in an C<SV>, growing the buffer if
2198necessary.
2c8edc25
S
2199
2200=item *
2201
0ebc1fcf
KW
2202A new API macro L<C<SvPVCLEAR()>|perlapi/SvPVCLEAR> sets its C<SV>
2203argument to an empty string,
c2ef64b1 2204like Perl-space C<$x = ''>, but with several optimisations.
2c8edc25
S
2205
2206=item *
2207
c11f9206 2208Several new macros and functions for dealing with Unicode and
fb5d4b1a
KW
2209UTF-8-encoded strings have been added to the API, as well as some
2210changes in
c11f9206
DM
2211functionality of existing functions (see L<perlapi/Unicode Support> for
2212more details):
2213
2214=over
2215
2216=item *
2217
0ebc1fcf
KW
2218New versions of the API macros like C<isALPHA_utf8> and C<toLOWER_utf8>
2219have been added, each with the suffix C<_safe>, like
2220L<C<isSPACE_utf8_safe>|perlapi/isSPACE>. These take an extra
2221parameter, giving an upper
2222limit of how far into the string it is safe to read. Using the old
2223versions could cause attempts to read beyond the end of the input buffer
2224if the UTF-8 is not well-formed, and their use now raises a deprecation
2225warning. Details are at L<perlapi/Character classification>.
2c8edc25
S
2226
2227=item *
2228
0ebc1fcf
KW
2229Macros like L<C<isALPHA_utf8>|perlapi/isALPHA> and
2230L<C<toLOWER_utf8>|perlapi/toLOWER_utf8> now die if they detect
ac6c7175
KW
2231that their input UTF-8 is malformed. A deprecation warning had been
2232issued since Perl 5.18.
2c8edc25
S
2233
2234=item *
2235
c11f9206
DM
2236Several new macros for analysing the validity of utf8 sequences. These
2237are:
2238
bfe8fcbb
KW
2239L<C<UTF8_GOT_ABOVE_31_BIT>|perlapi/UTF8_GOT_ABOVE_31_BIT>
2240L<C<UTF8_GOT_CONTINUATION>|perlapi/UTF8_GOT_CONTINUATION>
2241L<C<UTF8_GOT_EMPTY>|perlapi/UTF8_GOT_EMPTY>
2242L<C<UTF8_GOT_LONG>|perlapi/UTF8_GOT_LONG>
2243L<C<UTF8_GOT_NONCHAR>|perlapi/UTF8_GOT_NONCHAR>
2244L<C<UTF8_GOT_NON_CONTINUATION>|perlapi/UTF8_GOT_NON_CONTINUATION>
2245L<C<UTF8_GOT_OVERFLOW>|perlapi/UTF8_GOT_OVERFLOW>
2246L<C<UTF8_GOT_SHORT>|perlapi/UTF8_GOT_SHORT>
2247L<C<UTF8_GOT_SUPER>|perlapi/UTF8_GOT_SUPER>
2248L<C<UTF8_GOT_SURROGATE>|perlapi/UTF8_GOT_SURROGATE>
2249L<C<UTF8_IS_INVARIANT>|perlapi/UTF8_IS_INVARIANT>
2250L<C<UTF8_IS_NONCHAR>|perlapi/UTF8_IS_NONCHAR>
2251L<C<UTF8_IS_SUPER>|perlapi/UTF8_IS_SUPER>
2252L<C<UTF8_IS_SURROGATE>|perlapi/UTF8_IS_SURROGATE>
2253L<C<UVCHR_IS_INVARIANT>|perlapi/UVCHR_IS_INVARIANT>
2254L<C<isUTF8_CHAR_flags>|perlapi/isUTF8_CHAR_flags>
2255L<C<isSTRICT_UTF8_CHAR>|perlapi/isSTRICT_UTF8_CHAR>
2256L<C<isC9_STRICT_UTF8_CHAR>|perlapi/isC9_STRICT_UTF8_CHAR>
2c8edc25
S
2257
2258=item *
2259
0f032fe1 2260Functions that are all extensions of the C<is_utf8_string_I<*>()> functions,
c11f9206
DM
2261that apply various restrictions to the UTF-8 recognized as valid:
2262
bfe8fcbb
KW
2263L<C<is_strict_utf8_string>|perlapi/is_strict_utf8_string>,
2264L<C<is_strict_utf8_string_loc>|perlapi/is_strict_utf8_string_loc>,
2265L<C<is_strict_utf8_string_loclen>|perlapi/is_strict_utf8_string_loclen>,
c11f9206 2266
bfe8fcbb
KW
2267L<C<is_c9strict_utf8_string>|perlapi/is_c9strict_utf8_string>,
2268L<C<is_c9strict_utf8_string_loc>|perlapi/is_c9strict_utf8_string_loc>,
2269L<C<is_c9strict_utf8_string_loclen>|perlapi/is_c9strict_utf8_string_loclen>,
c11f9206 2270
bfe8fcbb
KW
2271L<C<is_utf8_string_flags>|perlapi/is_utf8_string_flags>,
2272L<C<is_utf8_string_loc_flags>|perlapi/is_utf8_string_loc_flags>,
2273L<C<is_utf8_string_loclen_flags>|perlapi/is_utf8_string_loclen_flags>,
c11f9206 2274
bfe8fcbb
KW
2275L<C<is_utf8_fixed_width_buf_flags>|perlapi/is_utf8_fixed_width_buf_flags>,
2276L<C<is_utf8_fixed_width_buf_loc_flags>|perlapi/is_utf8_fixed_width_buf_loc_flags>,
2277L<C<is_utf8_fixed_width_buf_loclen_flags>|perlapi/is_utf8_fixed_width_buf_loclen_flags>.
c11f9206 2278
bfe8fcbb
KW
2279L<C<is_utf8_invariant_string>|perlapi/is_utf8_invariant_string>.
2280L<C<is_utf8_valid_partial_char>|perlapi/is_utf8_valid_partial_char>.
2281L<C<is_utf8_valid_partial_char_flags>|perlapi/is_utf8_valid_partial_char_flags>.
2c8edc25
S
2282
2283=item *
2284
bfe8fcbb
KW
2285The functions L<C<utf8n_to_uvchr>|perlapi/utf8n_to_uvchr> and its
2286derivatives have had several changes of behaviour.
c11f9206
DM
2287
2288Calling them, while passing a string length of 0 is now asserted against
2289in DEBUGGING builds, and otherwise returns the Unicode REPLACEMENT
2290CHARACTER. If you have nothing to decode, you shouldn't call the decode
2291function.
2292
2293They now return the Unicode REPLACEMENT CHARACTER if called with UTF-8
2294that has the overlong malformation, and that malformation is allowed by
2295the input parameters. This malformation is where the UTF-8 looks valid
2296syntactically, but there is a shorter sequence that yields the same code
2297point. This has been forbidden since Unicode version 3.1.
2298
2299They now accept an input
2c8edc25
S
2300flag to allow the overflow malformation. This malformation is when the
2301UTF-8 may be syntactically valid, but the code point it represents is
2302not capable of being represented in the word length on the platform.
2303What "allowed" means in this case is that the function doesn't return an
fb5d4b1a
KW
2304error, and it advances the parse pointer to beyond the UTF-8 in
2305question, but it returns the Unicode REPLACEMENT CHARACTER as the value
2306of the code point (since the real value is not representable).
2c8edc25 2307
55b0afa5
KW
2308They no longer abandon searching for other malformations when the first
2309one is encountered. A call to one of these functions thus can generate
2310multiple diagnostics, instead of just one.
2c8edc25
S
2311
2312=item *
2313
0ebc1fcf
KW
2314L<C<valid_utf8_to_uvchr()>|perlapi/valid_utf8_to_uvchr> has been added
2315to the API (although it was
c11f9206 2316present in core earlier). Like C<utf8_to_uvchr_buf()>, but assumes that
fb5d4b1a 2317the next character is well-formed. Use with caution.
c11f9206
DM
2318
2319=item *
2320
bfe8fcbb
KW
2321A new function, L<C<utf8n_to_uvchr_error>|perlapi/utf8n_to_uvchr_error>,
2322has been added for
2c8edc25
S
2323use by modules that need to know the details of UTF-8 malformations
2324beyond pass/fail. Previously, the only ways to know why a sequence was
2325ill-formed was to capture and parse the generated diagnostics, or to do
2326your own analysis.
2327
2328=item *
2329
0ebc1fcf
KW
2330There is now a safer version of utf8_hop(), called
2331L<C<utf8_hop_safe()>|perlapi/utf8_hop_safe>.
c11f9206
DM
2332Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or
2333after the end of the supplied buffer.
2c8edc25
S
2334
2335=item *
2336
0ebc1fcf
KW
2337Two new functions, L<C<utf8_hop_forward()>|perlapi/utf8_hop_forward> and
2338L<C<utf8_hop_back()>|perlapi/utf8_hop_back> are
c11f9206
DM
2339similar to C<utf8_hop_safe()> but are for when you know which direction
2340you wish to travel.
2c8edc25
S
2341
2342=item *
2343
c11f9206
DM
2344Two new macros which return useful utf8 byte sequences:
2345
bfe8fcbb
KW
2346L<C<BOM_UTF8>|perlapi/BOM_UTF8>
2347L<C<REPLACEMENT_CHARACTER_UTF8>|perlapi/REPLACEMENT_CHARACTER_UTF8>
c11f9206
DM
2348
2349=back
c2ef64b1
DM
2350
2351=item *
2352
2353Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
2354default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2355This flag alters how the C<op_sibling> field is used in C<OP> structures,
2356and has been available optionally since perl 5.22.
2357
2358See L<perl5220delta/"Internal Changes"> for more details of what this
2359build option does.
2360
2361=item *
2362
2363Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
2364been added. These are intended principally to implement the individual
2365elements of a subroutine signature, plus any overall checking required.
2366
2367=item *
2368
0ebc1fcf
KW
2369The L<C<op_class()>|perlapi/op_class> API function has been added. This
2370is like the existing
c2ef64b1
DM
2371C<OP_CLASS()> macro, but can more accurately determine what struct an op
2372has been allocated as. For example C<OP_CLASS()> might return
2373C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2374allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2375C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2c8edc25
S
2376
2377=item *
2378
2379All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2380previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2381that several parts of the internals had to be special-cased to accommodate
95b17558 2382it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2c8edc25
S
2383that is now handled in a simpler way.
2384
2385=item *
2386
0ebc1fcf
KW
2387The output format of the L<C<op_dump()>|perlapi/op_dump> function (as
2388used by C<perl -Dx>)
c2ef64b1
DM
2389has changed: it now displays an "ASCII-art" tree structure, and shows more
2390low-level details about each op, such as its address and class.
2c8edc25
S
2391
2392=item *
2393
c2ef64b1
DM
2394The C<PADOFFSET> type has changed from being unsigned to signed, and
2395several pad-related variables such as C<PL_padix> have changed from being
2396of type C<I32> to type C<PADOFFSET>.
2c8edc25
S
2397
2398=item *
2399
c2ef64b1
DM
2400The C<DEBUGGING>-mode output for regex compilation and execution has been
2401enhanced.
2c8edc25
S
2402
2403=item *
2404
74ca8c9e
DM
2405Several obscure SV flags have been eliminated, sometimes along with the
2406macros which manipulate them: C<SVpbm_VALID>, C<SVpbm_TAIL>, C<SvTAIL_on>,
2407C<SvTAIL_off>, C<SVrepl_EVAL>, C<SvEVALED>
2c8edc25
S
2408
2409=item *
2410
74ca8c9e
DM
2411An OP op_private flag has been eliminated: C<OPpRUNTIME>. This used to
2412often get set on C<PMOP>s, but had become meaningless over time.
2c8edc25
S
2413
2414=back
2415
2416=head1 Selected Bug Fixes
2417
2418=over 4
2419
2420=item *
2421
5573eafe
DM
2422Perl no longer panics when switching into some locales on machines with
2423buggy C<strxfrm()> implementations in their libc. [perl #121734]
2424
2425=item *
2426
2c8edc25
S
2427C< $-{$name} > would leak an C<AV> on each access if the regular
2428expression had no named captures. The same applies to access to any
2429hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2430#130822]
2431
2432=item *
2433
2434Attempting to use the deprecated variable C<$#> as the object in an
2435indirect object method call could cause a heap use after free or
2436buffer overflow. [perl #129274]
2437
2438=item *
2439
2440When checking for an indirect object method call in some rare cases
2441the parser could reallocate the line buffer but then continue to use
2442pointers to the old buffer. [perl #129190]
2443
2444=item *
2445
0f032fe1
KW
2446Supplying a glob as the format argument to
2447L<C<formline>|perlfunc/formline> would
2c8edc25
S
2448cause an assertion failure. [perl #130722]
2449
2450=item *
2451
2452Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
0f032fe1 2453converted into a C<qr//> operator, leaving extra elements on the stack to
2c8edc25
S
2454confuse any surrounding expression. [perl #130705]
2455
2456=item *
2457
d3972b39 2458Since v5.24 in some obscure cases, a regex which included code blocks
0f032fe1 2459from multiple sources (I<e.g.>, via embedded via C<qr//> objects) could end up
2c8edc25
S
2460with the wrong current pad and crash or give weird results. [perl #129881]
2461
2462=item *
2463
2464Occasionally C<local()>s in a code block within a patterns weren't being
2465undone when the pattern matching backtracked over the code block.
2466[perl #126697]
2467
2468=item *
2469
2470Using C<substr()> to modify a magic variable could access freed memory
2471in some cases. [perl #129340]
2472
2473=item *
2474
2c8edc25 2475Under C<use utf8>, the entire Perl program is now checked that the UTF-8
fb5d4b1a 2476is wellformed. [perl #126310].
2c8edc25
S
2477
2478=item *
2479
df48f9a4 2480The range operator C<".."> on strings now handles its arguments correctly when in
2c8edc25 2481the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
95b17558 2482feature. The previous behaviour was sufficiently unexpected that we believe no
2c8edc25
S
2483correct program could have made use of it.
2484
2485=item *
2486
0f032fe1 2487The C<split> operator did not ensure enough space was allocated for
2c8edc25
S
2488its return value in scalar context. It could then write a single
2489pointer immediately beyond the end of the memory block allocated for
2490the stack. [perl #130262]
2491
2492=item *
2493
df48f9a4 2494Using a large code point with the C<"W"> pack template character with
2c8edc25
S
2495the current output position aligned at just the right point could
2496cause a write a single zero byte immediately beyond the end of an
2497allocated buffer. [perl #129149]
2498
2499=item *
2500
2501Supplying the form picture argument as part of the form argument list
2502where the picture specifies modifying the argument could cause an
2503access to the new freed compiled form. [perl #129125]
2504
2505=item *
2506
2507Fix a problem with sort's build-in compare, where it would not sort
2508correctly with 64-bit integers, and non-long doubles. [perl #130335]
2509
2510=item *
2511
0ebc1fcf
KW
2512Fix issues with C</(?{ ... E<lt>E<lt>EOF })/> that broke
2513L<Method::Signatures>. [perl #130398]
2c8edc25
S
2514
2515=item *
2516
2c8edc25
S
2517Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2518
2519=item *
2520
2521Fixed an assertion failure with C<chop> and C<chomp>, which
2522could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2523
2524=item *
2525
fb5d4b1a
KW
2526Fixed a comment skipping error in patterns under C</x>; it could stop
2527skipping a byte early, which could be in the middle of a UTF-8
2528character. [perl #130495].
2c8edc25
S
2529
2530=item *
2531
2532F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2533
2534=item *
2535
2536Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2537
2538=item *
2539
0f032fe1 2540DragonFly BSD now has support for C<setproctitle()>. [perl #130068].
2c8edc25
S
2541
2542=item *
2543
fb5d4b1a 2544Fix an assertion error which could be triggered when a lookahead string
2c8edc25
S
2545in patterns exceeded a minimum length. [perl #130522].
2546
2547=item *
2548
df48f9a4 2549Only warn once per literal about a misplaced C<"_">. [perl #70878].
2c8edc25
S
2550
2551=item *
2552
2553Ensure range-start is set after error in C<tr///>. [perl #129342].
2554
2555=item *
2556
2557Don't read past start of string for unmatched backref; otherwise,
2558we may have heap buffer overflow. [perl #129377].
2559
2560=item *
2561
2c8edc25 2562C<use re 'strict'> is supposed to warn if you use a range whose start
95b17558 2563and end digit aren't from the same group of 10. It didn't do that
2c8edc25
S
2564for five groups of mathematical digits starting at U+1D7E.
2565
2566=item *
2567
fce64130 2568A sub containing a "forward" declaration with the same name (I<e.g.>,
2c8edc25
S
2569C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2570#129090]
2571
2572=item *
2573
fb5d4b1a 2574A crash in executing a regex with a non-anchored UTF-8 substring against a
2c8edc25
S
2575target string that also used UTF-8 has been fixed. [perl #129350]
2576
2577=item *
2578
2579Previously, a shebang line like C<#!perl -i u> could be erroneously
95b17558 2580interpreted as requesting the C<-u> option. This has been fixed. [perl
2c8edc25
S
2581#129336]
2582
2583=item *
2584
2585The regex engine was previously producing incorrect results in some rare
2586situations when backtracking past a trie that matches only one thing; this
0f032fe1 2587showed up as capture buffers (C<$1>, C<$2>, I<etc.>) erroneously containing data
2c8edc25
S
2588from regex execution paths that weren't actually executed for the final
2589match. [perl #129897]
2590
2591=item *
2592
2593Certain regexes making use of the experimental C<regex_sets> feature could
95b17558 2594trigger an assertion failure. This has been fixed. [perl #129322]
2c8edc25
S
2595
2596=item *
2597
fce64130 2598Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
2c8edc25
S
2599sometimes crash in addition to giving a syntax error. [perl #125679]
2600
2601=item *
2602
2603The parser could sometimes crash if a bareword came after C<evalbytes>.
2604[perl #129196]
2605
2606=item *
2607
2608Autoloading via a method call would warn erroneously ("Use of inherited
2609AUTOLOAD for non-method") if there was a stub present in the package into
2610which the invocant had been blessed. The warning is no longer emitted in
2611such circumstances. [perl #47047]
2612
2613=item *
2614
2c8edc25
S
2615The use of C<splice> on arrays with nonexistent elements could cause other
2616operators to crash. [perl #129164]
2617
2618=item *
2619
2620Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2621string. [perl #129012]
2622
2623=item *
2624
2625Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2626checking that the I<current> C<cx> is the right type, and instead was always
2627checking the base C<cx> (effectively a noop). [perl #129029]
2628
2629=item *
2630
95b17558 2631Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2c8edc25
S
2632maintains up to two pointers into the parser buffer, one of which can
2633become stale under the right conditions. [perl #129069]
2634
2635=item *
2636
2637Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2638when it wasn't. [perl #129038]
2639
2640=item *
2641
2642Fixed place where regex was not setting the syntax error correctly.
2643[perl #129122]
2644
2645=item *
2646
df48f9a4 2647The C<&.> operator (and the C<"&"> operator, when it treats its arguments as
2c8edc25
S
2648strings) were failing to append a trailing null byte if at least one string
2649was marked as utf8 internally. Many code paths (system calls, regexp
2650compilation) still expect there to be a null byte in the string buffer
2651just past the end of the logical string. An assertion failure was the
2652result. [perl #129287]
2653
2654=item *
2655
2656Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2657silently truncates the supplied path if it won't fit into the C<sun_path>
95b17558 2658member of C<sockaddr_un>. This may change in the future, but for now
2c8edc25
S
2659check the path in theC<sockaddr> matches the desired path, and skip if
2660it doesn't. [perl #128095]
2661
2662=item *
2663
95b17558 2664Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2c8edc25
S
2665cases this is used in building error messages. [perl #128988]
2666
2667=item *
2668
570ce26a
KW
2669Fix segfault when run with C<-DC> options on DEBUGGING builds.
2670[perl #129106]
2c8edc25
S
2671
2672=item *
2673
2674Fixed the parser error handling for an 'C<:attr(foo>' that does not have
df48f9a4 2675an ending 'C<")">'.
2c8edc25
S
2676
2677=item *
2678
2679Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2680actually fixed two bugs, [perl #129064] and [perl #129176].
2681
2682=item *
2683
0f032fe1
KW
2684[perl #129267] rework C<gv_fetchmethod_pvn_flags> separator parsing to
2685prevent possible string overrun with invalid len in F<gv.c>
2c8edc25
S
2686
2687=item *
2688
2689Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2690where the source and destination of the sort are the same plain array, are
95b17558 2691optimised to do less copying around. Two side-effects of this optimisation
2c8edc25
S
2692were that the contents of C<@a> as visible to to sort routine were
2693partially sorted, and under some circumstances accessing C<@a> during the
95b17558 2694sort could crash the interpreter. Both these issues have been fixed, and
2c8edc25
S
2695Sort functions see the original value of C<@a>.
2696
2697=item *
2698
2699Non-ASCII string delimiters are now reported correctly in error messages
2700for unterminated strings. [perl #128701]
2701
2702=item *
2703
2704C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2705temporary value") erroneously in some cases, but has been fixed.
2706
2707=item *
2708
2709C<@DB::args> is now exempt from "used once" warnings. The warnings only
2710occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2711multiple times.
2712
2713=item *
2714
2715The use of built-in arrays or hash slices in a double-quoted string no
2716longer issues a warning ("Possible unintended interpolation...") if the
2717variable has not been mentioned before. This affected code like
2718C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2719C<@-> and C<@+> were already exempt from the warning.)
2720
2721=item *
2722
2723C<gethostent> and similar functions now perform a null check internally, to
d3972b39 2724avoid crashing with torsocks. This was a regression from v5.22. [perl
2c8edc25
S
2725#128740]
2726
2727=item *
2728
2729C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2730memory if the typeglob in question has never been accessed before.
2731
2732=item *
2733
2c8edc25
S
2734Mentioning the same constant twice in a row (which is a syntax error) no
2735longer fails an assertion under debugging builds. This was a regression
d3972b39 2736from v5.20. [perl #126482]
2c8edc25
S
2737
2738=item *
2739
2740Many issues relating to C<printf "%a"> of hexadecimal floating point
2741were fixed. In addition, the "subnormals" (formerly known as "denormals")
fb5d4b1a 2742floating point numbers are now supported both with the plain IEEE 754
2c8edc25
S
2743floating point numbers (64-bit or 128-bit) and the x86 80-bit
2744"extended precision". Note that subnormal hexadecimal floating
2745point literals will give a warning about "exponent underflow".
2746[perl #128843, #128889, #128890, #128893, #128909, #128919]
2747
2748=item *
2749
d3972b39 2750A regression in v5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2c8edc25
S
2751128 and 255 has been fixed. [perl #128734].
2752
2753=item *
2754
2c8edc25
S
2755Use of a string delimiter whose code point is above 2**31 now works
2756correctly on platforms that allow this. Previously, certain characters,
2757due to truncation, would be confused with other delimiter characters
df48f9a4 2758with special meaning (such as C<"?"> in C<m?...?>), resulting
2c8edc25
S
2759in inconsistent behaviour. Note that this is non-portable,
2760and is based on Perl's extension to UTF-8, and is probably not
2761displayable nor enterable by any editor. [perl #128738]
2762
2763=item *
2764
df48f9a4 2765C<@{x> followed by a newline where C<"x"> represents a control or non-ASCII
2c8edc25
S
2766character no longer produces a garbled syntax error message or a crash.
2767[perl #128951]
2768
2769=item *
2770
2771An assertion failure with C<%: = 0> has been fixed.
2772L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2773
2774=item *
2775
2776In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2777that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2778was to parse it as C<$foo:: . $bar>, has been restored.
2779L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2780
2781=item *
2782
2783Since Perl 5.20, line numbers have been off by one when perl is invoked with
2784the B<-x> switch. This has been fixed.
2785L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2786
2787=item *
2788
fce64130 2789Vivifying a subroutine stub in a deleted stash (I<e.g.>, C<delete $My::{"Foo::"};
2c8edc25
S
2790\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2791L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2792
2793=item *
2794
2795Some obscure cases of subroutines and file handles being freed at the same time
2796could result in crashes, but have been fixed. The crash was introduced in Perl
27975.22.
2798L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2799
2800=item *
2801
2802Code that looks for a variable name associated with an uninitialized value
fb5d4b1a 2803could cause an assertion failure in cases where magic is involved, such as
2c8edc25
S
2804C<$ISA[0][0]>. This has now been fixed.
2805L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2806
2807=item *
2808
2809A crash caused by code generating the warning "Subroutine STASH::NAME
2810redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2811fixed. In these cases, where the STASH is missing, the warning will now appear
2812as "Subroutine NAME redefined".
2813L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2814
2815=item *
2816
2817Fixed an assertion triggered by some code that handles deprecated behavior in
fce64130 2818formats, I<e.g.>, in cases like this:
2c8edc25
S
2819
2820 format STDOUT =
2821 @
2822 0"$x"
2823
2824L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2825
2826=item *
2827
2828A possible divide by zero in string transformation code on Windows has been
2829avoided, fixing a crash when collating an empty string.
2830L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2831
2832=item *
2833
2834Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2835regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2836L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2837
2838=item *
2839
2840C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2841warn when syntax warnings are enabled. [perl #127333]
2842
2843=item *
2844
2845socket() now leaves the error code returned by the system in C<$!> on
2846failure. [perl #128316]
2847
2848=item *
2849
2850Assignment variants of any bitwise ops under the C<bitwise> feature would
2851crash if the left-hand side was an array or hash. [perl #128204]
2852
2853=item *
2854
2855C<require> followed by a single colon (as in C<foo() ? require : ...> is
0f032fe1 2856now parsed correctly as C<require> with implicit C<$_>, rather than
2c8edc25
S
2857C<require "">. [perl #128307]
2858
2859=item *
2860
2861Scalar C<keys %hash> can now be assigned to consistently in all scalar
2862lvalue contexts. Previously it worked for some contexts but not others.
2863
2864=item *
2865
2866List assignment to C<vec> or C<substr> with an array or hash for its first
2867argument used to result in crashes or "Can't coerce" error messages at run
2868time, unlike scalar assignment, which would give an error at compile time.
2869List assignment now gives a compile-time error, too. [perl #128260]
2870
2871=item *
2872
2873Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
95b17558 2874and C<or>) were being compiled incorrectly in some cases. If the left-hand
2c8edc25
S
2875side consisted of either a negated bareword constant or a negated C<do {}>
2876block containing a constant expression, and the right-hand side consisted of
2877a negated non-foldable expression, one of the negations was effectively
95b17558
KW
2878ignored. The same was true of C<if> and C<unless> statement modifiers,
2879though with the left-hand and right-hand sides swapped. This long-standing
2c8edc25
S
2880bug has now been fixed. [perl #127952]
2881
2882=item *
2883
2884C<reset> with an argument no longer crashes when encountering stash entries
2885other than globs. [perl #128106]
2886
2887=item *
2888
2889Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2890longer causes crashes. [perl #128086]
2891
2892=item *
2893
0f032fe1 2894Handle C<SvIMMORTALs> in LHS of list assign. [perl #129991]
2c8edc25
S
2895
2896=item *
2897
fc751fe1 2898Assertion failure with user-defined Unicode-like properties. [perl #130010]
2c8edc25
S
2899
2900=item *
2901
2902Fix error message for unclosed C<\N{> in regcomp.
2903
2904An unclosed C<\N{> could give the wrong error message
2905C<"\N{NAME} must be resolved by the lexer">.
2906
2907=item *
2908
2909List assignment in list context where the LHS contained aggregates and
2910where there were not enough RHS elements, used to skip scalar lvalues.
2911Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
95b17558
KW
2912it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2913returns C<($a,$b,$c)>. This can be seen in the following:
2c8edc25
S
2914
2915 sub inc { $_++ for @_ }
2916 inc(($a,$b,@c,$d) = (10))
2917
2918Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2919now they are C<(11,1,1)>.
2920
2921=item *
2922
f632cffa
KW
2923Code like this: C</(?{ s!!! })/> can trigger infinite recursion on the C
2924stack (not the normal perl stack) when the last successful pattern in
2925scope is itself. We avoid the segfault by simply forbidding the use of
2926the empty pattern when it would resolve to the currently executing
2927pattern. [perl 129903]
2c8edc25
S
2928
2929=item *
2930
0c092f6b
KW
2931Avoid reading beyond the end of the line buffer when there's a
2932short UTF-8 character at the end. [perl 128997]
2c8edc25
S
2933
2934=item *
2935
0c092f6b 2936Fix firstchar bitmap under utf8 with prefix optimisation. [perl 129950]
2c8edc25
S
2937
2938=item *
2939
0c092f6b 2940Make F<Carp/t/arg_string.t>: be liberal in C<f>/C<p> formats. [perl 129954]
2c8edc25
S
2941
2942=item *
2943
0c092f6b 2944Make C<do "a\0b"> fail silently instead of throwing an error. [perl 129928]
2c8edc25
S
2945
2946=item *
2947
0c092f6b 2948Make C<chdir> allocate the stack it needs. [perl 129130]
2c8edc25
S
2949
2950=back
2951
2952=head1 Known Problems
2953
2954=over 4
2955
2956=item *
2957
2958Some modules have been broken by the L<context stack rework|/Internal Changes>.
fb5d4b1a
KW
2959These modules were relying on non-guaranteed implementation details in
2960the perl interpreter.
2c8edc25
S
2961Their maintainers have been informed, and should contact perl5-porters for
2962advice if needed. Below is a subset of these modules:
2963
2964=over 4
2965
2966=item * L<Algorithm::Permute>
2967
2968=item * L<Coro>
2969
fb5d4b1a
KW
2970L<Coro> and Perl 5.22 were already incompatible due to a change in the perl
2971interpreter,
2c8edc25
S
2972and the reworking on the perl context stack creates a further incompatibility.
2973perl5-porters has L<discussed the issue on the mailing
2974list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
2975
2976=item * L<Data::Alias>
2977
2978=item * L<RPerl>
2979
2980=item * L<Scope::Upper>
2981
2982=item * L<TryCatch>
2983
2984=back
2985
2986=item *
2987
53799a91 2988The module L<lexical::underscore> no longer works on Perl 5.24, because perl
2c8edc25
S
2989no longer has a lexical C<$_>!
2990
2991=item *
2992
53799a91 2993C<mod_perl> has been patched for compatibility for v5.22 and later but no
2c8edc25
S
2994release has been made. The relevant patch (and other changes) can be found in
2995their source code repository, L<mirrored at
2996GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
2997
2998=back
2999
3000=head1 Errata From Previous Releases
3001
3002=over 4
3003
3004=item *
3005
ee8180b8 3006Parsing bad POSIX charclasses no longer leaks memory.
2c8edc25
S
3007L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
3008
3009=item *
3010
53799a91 3011Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
2c8edc25
S
3012L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
3013
3014=back
3015
3016=head1 Obituary
3017
3018Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
95b17558 3019member, has passed away on August 10, 2016. He will be remembered and
c94c0e4f 3020missed by all those who he came in contact with, and enriched with his
2c8edc25
S
3021intellect, wit, and spirit.
3022
c94c0e4f 3023It is with great sadness that we also note Kip Hampton's passing. Probably
2c8edc25
S
3024best known as the author of the Perl & XML column on XML.com, he was a
3025core contributor to AxKit, an XML server platform that became an Apache
95b17558
KW
3026Foundation project. He was a frequent speaker in the early days at
3027OSCON, and most recently at YAPC::NA in Madison. He was frequently on
2c8edc25
S
3028irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
3029group responsible for YAPC::NA Asheville in 2011.
a049258c 3030
2c8edc25
S
3031Kip and his constant contributions to the community will be greatly
3032missed.
a049258c
S
3033
3034=head1 Acknowledgements
2e0dcc12 3035
0cc8c746 3036Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 3037and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
S
3038authors.
3039
3040Excluding auto-generated files, documentation and release tools, there were
3041approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
3042
3043Perl continues to flourish into its third decade thanks to a vibrant community
95b17558 3044of users and developers. The following people are known to have contributed the
ad543fb2 3045improvements that became Perl 5.26.0:
0cc8c746
S
3046
3047Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
3048König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
3049Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
3050Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
3051Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
3052Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3053Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3054Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3055D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3056Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3057De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3058Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3059Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3060Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3061Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3062Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3063Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3064Yves Orton, Zefram.
0cc8c746
S
3065
3066The list above is almost certainly incomplete as it is automatically generated
95b17558 3067from version control history. In particular, it does not include the names of
0cc8c746
S
3068the (very much appreciated) contributors who reported issues to the Perl bug
3069tracker.
3070
3071Many of the changes included in this version originated in the CPAN modules
95b17558 3072included in Perl's core. We're grateful to the entire CPAN community for
0cc8c746
S
3073helping Perl to flourish.
3074
3075For a more complete list of all of Perl's historical contributors, please see
3076the F<AUTHORS> file in the Perl source distribution.
f5b73711 3077
44691e6f
AB
3078=head1 Reporting Bugs
3079
2c8edc25
S
3080If you find what you think is a bug, you might check the articles recently
3081posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3082L<https://rt.perl.org/> . There may also be information at
4b8803f0 3083L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3084
e08634c5
SH
3085If you believe you have an unreported bug, please run the L<perlbug> program
3086included with your release. Be sure to trim your bug down to a tiny but
3087sufficient test case. Your bug report, along with the output of C<perl -V>,
7c825fca 3088will be sent off to C<perlbug@perl.org> to be analysed by the Perl porting team.
44691e6f 3089
87c118b9
DM
3090If the bug you are reporting has security implications which make it
3091inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3092L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3093for details of how to report the issue.
44691e6f
AB
3094
3095=head1 SEE ALSO
3096
e08634c5
SH
3097The F<Changes> file for an explanation of how to view exhaustive details on
3098what changed.
44691e6f
AB
3099
3100The F<INSTALL> file for how to build Perl.
3101
3102The F<README> file for general stuff.
3103
3104The F<Artistic> and F<Copying> files for copyright information.
3105
3106=cut