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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
15a20477 1279=head3 L<perlmod>
2c8edc25
S
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
473ac7a0
KW
1429See L</Declaring a reference to a variable>.
1430
2c8edc25
S
1431=item *
1432
1433L<Version control conflict marker|perldiag/"Version control conflict marker">
1434
e6abae1c 1435(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
95b17558 1436C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
2c8edc25
S
1437version control system to mark conflicts after a failed merge operation.
1438
1439=item *
1440
1441L<%s: command not found|perldiag/"%s: command not found">
1442
1443(A) You've accidentally run your script through B<bash> or another shell
068a1201
KW
1444instead of Perl. Check the C<#!> line, or manually feed your script into
1445Perl yourself. The C<#!> line at the top of your file could look like:
2c8edc25
S
1446
1447 #!/usr/bin/perl
1448
1449=item *
1450
1451L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1452
1453(A) You've accidentally run your script through B<zsh> or another shell
068a1201
KW
1454instead of Perl. Check the C<#!> line, or manually feed your script into
1455Perl yourself. The C<#!> line at the top of your file could look like:
2c8edc25
S
1456
1457 #!/usr/bin/perl
1458
1459=item *
1460
a6733086 1461L<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 1462
d8362e1b
KW
1463Unescaped left braces are now illegal in some contexts in regular expression
1464patterns. In other contexts, they are still just deprecated; they will
1465be illegal in Perl 5.30.
2c8edc25
S
1466
1467=item *
1468
1469L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1470
1471=item *
1472
1473L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1474
1475=item *
1476
1477L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1478
1479=item *
1480
1481L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1482
1483=back
1484
1485=head3 New Warnings
1486
1487=over 4
1488
1489=item *
1490
4f73c567 1491L<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
1492
1493See L</Deprecations>
1494
1495=item *
1496
1497L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1498
1499(S experimental::declared_refs) This warning is emitted if you use a reference
1500constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1501C<local()>. Simply suppress the warning if you want to use the feature, but
1502know that in doing so you are taking the risk of using an experimental feature
1503which may change or be removed in a future Perl version:
1504
1505 no warnings "experimental::declared_refs";
1506 use feature "declared_refs";
1507 $fooref = my \$foo;
1508
473ac7a0
KW
1509See L</Declaring a reference to a variable>.
1510
2c8edc25
S
1511=item *
1512
4f73c567 1513L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25 1514
0f275d26 1515The special variable C<${^ENCODING}>, formerly used to implement
53799a91 1516the C<encoding> pragma, is no longer supported as of Perl 5.26.
2c8edc25 1517
89853d76
DH
1518=item *
1519
df48f9a4 1520Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
89853d76
DH
1521a warning recommending to fix the C<do> statement:
1522
fc902710 1523L<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 1524
2c8edc25
S
1525=back
1526
1527=head2 Changes to Existing Diagnostics
1528
1529=over 4
1530
1531=item *
1532
1533When a C<require> fails, we now do not provide C<@INC> when the C<require>
1534is for a file instead of a module.
1535
1536=item *
1537
1538When C<@INC> is not scanned for a C<require> call, we no longer display
1539C<@INC> to avoid confusion.
1540
1541=item *
1542
02e0a8e8
KW
1543Details as to the exact problem have been added to the diagnostics that
1544occur when malformed UTF-8 is encountered when trying to convert to a
1545code point.
1546
1547=item *
1548
cf3a543f
KW
1549L<Attribute "locked" is deprecated, and will disappear in Perl 5.28
1550|perldiag/Attribute "locked" is deprecated, and will disappear in Perl 5.28>
2c8edc25
S
1551
1552=item *
1553
cf3a543f
KW
1554L<Attribute "unique" is deprecated, and will disappear in Perl 5.28
1555|perldiag/Attribute "unique" is deprecated, and will disappear in Perl 5.28>
2c8edc25
S
1556
1557=item *
1558
cf3a543f
KW
1559L<Constants from lexical variables potentially modified elsewhere are deprecated. This will not be allowed in Perl 5.32
1560|perldiag/Constants from lexical variables potentially modified elsewhere are deprecated. This will not be allowed in Perl 5.32>
2c8edc25
S
1561
1562=item *
1563
cf3a543f
KW
1564L<Deprecated use of C<my()> in false conditional. This will be a fatal error in Perl 5.30
1565|perldiag/Deprecated use of C<my()> in false conditional. This will be a fatal error in Perl 5.30>
2c8edc25
S
1566
1567=item *
1568
cf3a543f
KW
1569L<C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available in Perl 5.30
1570|perldiag/C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available in Perl 5.30>
2c8edc25
S
1571
1572=item *
1573
cf3a543f
KW
1574L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28
1575|perldiag/C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28>
2c8edc25
S
1576
1577=item *
1578
cf3a543f
KW
1579L<Experimental %s on scalar is now forbidden This message now is followed by more helpful text. [perl #127976]
1580|perldiag/Experimental %s on scalar is now forbidden>.
906e28fb
KW
1581This message now is followed by more helpful text. [perl #127976]
1582
1583=item *
1584
cf3a543f
KW
1585L<C<File::Glob::glob()> will disappear in perl 5.30. Use C<File::Glob::bsd_glob()> instead.
1586|perldiag/C<File::Glob::glob()> will disappear in perl 5.30. Use C<File::Glob::bsd_glob()> instead.>
2c8edc25
S
1587
1588=item *
1589
cf3a543f
KW
1590L<%s() is deprecated on C<:utf8> handles. This will be a fatal error in Perl 5.30
1591|perldiag/%s() is deprecated on C<:utf8> handles. This will be a fatal error in Perl 5.30>.
d0d6ad19 1592"%s" is one of C<sysread>, C<recv>, C<syswrite>, or C<send>.
2c8edc25
S
1593
1594=item *
1595
cf3a543f
KW
1596L<C<$*> is no longer supported. Its use will be fatal in Perl 5.30
1597|perldiag/C<$*> is no longer supported. Its use will be fatal in Perl 5.30>
2c8edc25
S
1598
1599=item *
1600
cf3a543f
KW
1601L<Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1602|perldiag/Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28>
2c8edc25
S
1603
1604=item *
1605
cf3a543f
KW
1606L<Opening filehandle %s also as a directory. This will be a fatal error in Perl 5.28
1607|perldiag/Opening filehandle %s also as a directory. This will be a fatal error in Perl 5.28>
2c8edc25
S
1608
1609=item *
1610
cf3a543f
KW
1611L<Setting C<$/> to a reference to %s as a form of slurp is deprecated, treating as undef. This will be fatal in Perl 5.28
1612|perldiag/Setting C<$/> to a reference to %s as a form of slurp is deprecated, treating as undef. This will be fatal in Perl 5.28>
2c8edc25
S
1613
1614=item *
1615
cf3a543f
KW
1616L<Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in mE<sol>%sE<sol>
1617|perldiag/Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/>
2c8edc25
S
1618
1619=item *
1620
cf3a543f
KW
1621L<Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1622|perldiag/Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28>
2c8edc25
S
1623
1624=item *
1625
cf3a543f
KW
1626L<Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1627|perldiag/Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28>
2c8edc25
S
1628
1629=item *
1630
cf3a543f
KW
1631L<Use of code point 0x%s is deprecated; the permissible max is 0x%s. This will be fatal in Perl 5.28
1632|perldiag/Use of code point 0x%s is deprecated; the permissible max is 0x%s. This will be fatal in Perl 5.28>
2c8edc25
S
1633
1634=item *
1635
cf3a543f
KW
1636L<Use of comma-less variable list is deprecated. Its use will be fatal in Perl 5.28
1637|perldiag/Use of comma-less variable list is deprecated. Its use will be fatal in Perl 5.28>
2c8edc25
S
1638
1639=item *
1640
cf3a543f
KW
1641L<Use of inherited C<AUTOLOAD> for non-method %s() is deprecated. This will be fatal in Perl 5.28
1642|perldiag/Use of inherited C<AUTOLOAD> for non-method %s() is deprecated. This will be fatal in Perl 5.28>
2c8edc25
S
1643
1644=item *
1645
cf3a543f
KW
1646L<Use of strings with code points over 0xFF as arguments to %s operator is deprecated. This will be a fatal error in Perl 5.28
1647|perldiag/Use of strings with code points over 0xFF as arguments to %s operator is deprecated. This will be a fatal error in Perl 5.28>
2c8edc25 1648
2c8edc25
S
1649=back
1650
1651=head1 Utility Changes
1652
1653=head2 F<c2ph> and F<pstruct>
1654
1655=over 4
1656
1657=item *
1658
1659These old utilities have long since superceded by L<h2xs>, and are
1660now gone from the distribution.
1661
1662=back
1663
1664=head2 F<Porting/pod_lib.pl>
1665
1666=over 4
1667
1668=item *
1669
1670Removed spurious executable bit.
1671
1672=item *
1673
fb5d4b1a 1674Account for the possibility of DOS file endings.
2c8edc25
S
1675
1676=back
1677
1678=head2 F<Porting/sync-with-cpan>
1679
1680=over 4
1681
1682=item *
1683
1684Many improvements
1685
1686=back
1687
1688=head2 F<perf/benchmarks>
1689
1690=over 4
1691
1692=item *
1693
1694Tidy file, rename some symbols.
1695
1696=back
1697
1698=head2 F<Porting/checkAUTHORS.pl>
1699
1700=over 4
1701
1702=item *
1703
0f275d26 1704Replace obscure character range with C<\w>.
2c8edc25
S
1705
1706=back
1707
1708=head2 F<t/porting/regen.t>
1709
1710=over 4
1711
1712=item *
1713
1714try to be more helpful when tests fail.
1715
1716=back
1717
1718=head2 F<utils/h2xs.PL>
1719
1720=over 4
1721
1722=item *
1723
1724Avoid infinite loop for enums.
1725
1726=back
1727
1728=head2 L<perlbug>
1729
1730=over 4
1731
1732=item *
1733
1734Long lines in the message body are now wrapped at 900 characters, to stay
1735well within the 1000-character limit imposed by SMTP mail transfer agents.
1736This is particularly likely to be important for the list of arguments to
1737C<Configure>, which can readily exceed the limit if, for example, it names
95b17558 1738several non-default installation paths. This change also adds the first unit
2c8edc25
S
1739tests for perlbug. [perl #128020]
1740
1741=back
1742
1743=head1 Configuration and Compilation
1744
1745=over 4
1746
1747=item *
1748
89853d76 1749C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1750
1751=item *
1752
18618fea 1753The C<dtrace> build process has further changes [perl #130108]:
2c8edc25
S
1754
1755=over
1756
1757=item *
1758
1759If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1760built within a FreeBSD jail.
1761
1762=item *
1763
1764On systems that build a dtrace object file (FreeBSD, Solaris and
1765SystemTap's dtrace emulation), copy the input objects to a separate
1766directory and process them there, and use those objects in the link,
1767since C<dtrace -G> also modifies these objects.
1768
1769=item *
1770
1771Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1772to libelf symbols.
1773
1774=item *
1775
1776Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1777default build on Solaris generates probes from the unused inline
1778functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1779fail.
1780
1781=back
1782
2c8edc25
S
1783=item *
1784
0f032fe1
KW
1785You can now disable perl's use of the C<PERL_HASH_SEED> and
1786C<PERL_PERTURB_KEYS> environment variables by configuring perl with
2c8edc25
S
1787C<-Accflags=NO_PERL_HASH_ENV>.
1788
1789=item *
1790
0f032fe1 1791You can now disable perl's use of the C<PERL_HASH_SEED_DEBUG> environment
2c8edc25
S
1792variable by configuring perl with
1793C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1794
1795=item *
1796
1797Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1798and C<Inf> to make builds more reproducible. [perl #130133]
1799
1800=item *
1801
fb5d4b1a 1802Since v5.18 for testing purposes, we have included support for
2c8edc25 1803building perl with a variety of non-standard, and non-recommended
95b17558
KW
1804hash functions. Since we do not recommend the use of these functions
1805we have removed them and their corresponding build options. Specifically
2c8edc25
S
1806this includes the following build options:
1807
1808 PERL_HASH_FUNC_SDBM
1809 PERL_HASH_FUNC_DJB2
1810 PERL_HASH_FUNC_SUPERFAST
1811 PERL_HASH_FUNC_MURMUR3
1812 PERL_HASH_FUNC_ONE_AT_A_TIME
1813 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1814 PERL_HASH_FUNC_MURMUR_HASH_64A
1815 PERL_HASH_FUNC_MURMUR_HASH_64B
1816
1817=item *
1818
1819Remove "Warning: perl appears in your path"
1820
1821This install warning is more or less obsolete, since most platforms already
0f032fe1 1822B<will> have a F</usr/bin/perl> or similar provided by the OS.
2c8edc25
S
1823
1824=item *
1825
0f032fe1 1826Reduce verbosity of C<make install.man>
2c8edc25
S
1827
1828Previously, two progress messages were emitted for each manpage: one by
1829installman itself, and one by the function in install_lib.pl that it calls to
95b17558 1830actually install the file. Disabling the second of those in each case saves
2c8edc25
S
1831over 750 lines of unhelpful output.
1832
1833=item *
1834
5d7d637c 1835Cleanup for C<clang -Weverything> support. [perl #129961]
2c8edc25
S
1836
1837=item *
1838
1839Configure: signbit scan was assuming too much, stop assuming negative 0.
1840
1841=item *
1842
1843Various compiler warnings have been silenced.
1844
1845=item *
1846
1847Several smaller changes have been made to remove impediments to compiling under
1848C++11.
1849
1850=item *
1851
1852Builds using C<USE_PAD_RESET> now work again; this configuration had
1853bit-rotted.
1854
1855=item *
1856
1857A probe for C<gai_strerror> was added to F<Configure> that checks if the
0f032fe1
KW
1858the C<gai_strerror()> routine is available and can be used to
1859translate error codes returned by C<getaddrinfo()> into human
2c8edc25
S
1860readable strings.
1861
1862=item *
1863
0f032fe1 1864F<Configure> now aborts if both C<-Duselongdouble> and C<-Dusequadmath> are
2c8edc25
S
1865requested.
1866L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1867
1868=item *
1869
0f032fe1 1870Fixed a bug in which F<Configure> could append C<-quadmath> to the archname even
2c8edc25
S
1871if it was already present.
1872L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1873
1874=item *
1875
0f032fe1
KW
1876Clang builds with C<-DPERL_GLOBAL_STRUCT> or
1877C<-DPERL_GLOBAL_STRUCT_PRIVATE> have
2c8edc25
S
1878been fixed (by disabling Thread Safety Analysis for these configurations).
1879
1880=item *
1881
1882F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
1883files require updates. This could cause dependencies, F<perlmain.c>
1884in particular, to be rebuilt unnecessarily. [perl #126710]
1885
1886=item *
1887
1888The output of C<perl -V> has been reformatted so that each configuration
1889and compile-time option is now listed one per line, to improve
1890readability.
1891
1892=item *
1893
1894C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
1895invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
1896This means you can supply your target platform C<config.sh>, generate
1897the headers and proceed to build your cross-target perl. [perl #127234]
1898
1899=item *
1900
1901Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
1902counts when the environment variable C<PERL_TRACE_OPS> to be set to a
1903non-zero integer. This allows C<make test> to pass on such a build.
1904
1905=item *
1906
1907When building with GCC 6 and link-time optimization (the C<-flto> option to
1908C<gcc>), C<Configure> was treating all probed symbols as present on the
95b17558 1909system, regardless of whether they actually exist. This has been fixed.
2c8edc25
S
1910[perl #128131]
1911
1912=item *
1913
1914The F<t/test.pl> library is used for internal testing of Perl itself, and
95b17558 1915also copied by several CPAN modules. Some of those modules must work on
2c8edc25 1916older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
95b17558 1917features. Compatibility with Perl 5.8 was inadvertently removed some time
2c8edc25
S
1918ago; it has now been restored. [perl #128052]
1919
1920=item *
1921
1922The build process no longer emits an extra blank line before building each
1923"simple" extension (those with only F<*.pm> and F<*.pod> files).
1924
1925=back
1926
1927=head1 Testing
1928
dd84ba97
KW
1929Tests were added and changed to reflect the other additions and changes
1930in this release. In addition, these substantive changes were made:
1931
2c8edc25
S
1932=over 4
1933
1934=item *
1935
dd84ba97
KW
1936A new test script, F<comp/parser_run.t>, has been added to test
1937reads through invalid pointers.
2c8edc25
S
1938
1939=item *
1940
1941Tests for locales were erroneously using locales incompatible with Perl.
1942
1943=item *
1944
1945Some parts of the test suite that try to exhaustively test edge cases in the
1946regex implementation have been restricted to running for a maximum of five
95b17558 1947minutes. On slow systems they could otherwise take several hours, without
2c8edc25
S
1948significantly improving our understanding of the correctness of the code
1949under test.
1950
1951In addition, some of those test cases have been split into more files, to
1952allow them to be run in parallel on suitable systems.
1953
1954=item *
1955
1956A new internal facility allows analysing the time taken by the individual
1957tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
1958
1959=item *
1960
1961F<t/re/regexp_nonull.t> has been added to test that the regular expression
1962engine can handle scalars that do not have a null byte just past the end of
1963the string.
1964
1965=item *
1966
0ebc1fcf
KW
1967A new test script, F<t/op/decl-refs.t>, has been added to test the new feature
1968L</Declaring a reference to a variable>.
2c8edc25
S
1969
1970=item *
1971
dd84ba97
KW
1972A new test script, F<t/re/keep_tabs.t> has been added to contain tests
1973where C<\t> characters should not be expanded into spaces.
1974
1975=item *
1976
2c8edc25
S
1977A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
1978generated by bracketed character classes are as expected.
1979
1980=item *
1981
dd84ba97
KW
1982There is now more extensive testing of the Unicode-related API macros
1983and functions.
1984
1985=item *
1986
1987Several of the longer running API test files have been split into
1988multiple test files so that they can be run in parallel.
1989
1990=item *
1991
2c8edc25
S
1992F<t/harness> now tries really hard not to run tests outside of the Perl
1993source tree. [perl #124050]
1994
1995=back
1996
1997=head1 Platform Support
1998
1999=head2 New Platforms
2000
2001=over 4
2002
2003=item NetBSD/VAX
2004
2005Perl now compiles under NetBSD on VAX machines. However, it's not
2006possible for that platform to implement floating-point infinities and
2007NaNs compatibly with most modern systems, which implement the IEEE-754
2008floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2009literals, C<printf %a>) is not implemented, either.
2010The C<make test> passes 98% of tests.
2011
2012=over 4
2013
2014=item *
2015
2016Test fixes and minor updates.
2017
2018=item *
2019
2020Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2021
2022=back
2023
2024=back
2025
2026=head2 Platform-Specific Notes
2027
2028=over 4
2029
2030=item Darwin
2031
0f032fe1
KW
2032don't treat C<-Dprefix=/usr> as special, instead require an extra option
2033C<-Ddarwin_distribution> to produce the same results.
2c8edc25
S
2034
2035=item POSIX
2036
2037Finish removing POSIX deprecated functions.
2038
2039=item OS X
2040
0f032fe1
KW
2041OS X El Capitan doesn't implement the C<clock_gettime()> or
2042C<clock_getres()> APIs; emulate them as necessary.
2c8edc25
S
2043
2044=item macOS
2045
0f032fe1 2046Deprecated C<syscall(2)> on macOS 10.12.
2c8edc25
S
2047
2048=item EBCDIC
2049
2050Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2051
2052=item HP-UX
2053
2054L<Net::Ping> UDP test is skipped on HP-UX.
2055
2056=item Hurd
2057
2058The hints for Hurd have been improved enabling malloc wrap and reporting the
2059GNU libc used (previously it was an empty string when reported).
2060
2061=item VAX
2062
29ce4d71 2063VAX floating point formats are now supported on NetBSD.
2c8edc25
S
2064
2065=item VMS
2066
2067=over 4
2068
2069=item *
2070
2071The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
df48f9a4
KW
2072now a colon (C<":">) when running under a Unix shell. There is no change when
2073running under DCL (it's still C<"|">).
2c8edc25
S
2074
2075=item *
2076
29ce4d71
CB
2077C<configure.com> now recognizes the VSI-branded C compiler and no longer
2078recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
207915 or more years).
2c8edc25
S
2080
2081=back
2082
2083=item Windows
2084
2085=over 4
2086
2087=item *
2088
2089Support for compiling perl on Windows using Microsoft Visual Studio 2015
2090(containing Visual C++ 14.0) has been added.
2091
2092This version of VC++ includes a completely rewritten C run-time library, some
0f032fe1
KW
2093of the changes in which mean that work done to resolve a socket
2094C<close()> bug in
2c8edc25
S
2095perl #120091 and perl #118059 is not workable in its current state with this
2096version of VC++. Therefore, we have effectively reverted that bug fix for
2097VS2015 onwards on the basis that being able to build with VS2015 onwards is
2098more important than keeping the bug fix. We may revisit this in the future to
2099attempt to fix the bug again in a way that is compatible with VS2015.
2100
2101These changes do not affect compilation with GCC or with Visual Studio versions
fce64130 2102up to and including VS2013, I<i.e.>, the bug fix is retained (unchanged) for those
2c8edc25
S
2103compilers.
2104
2105Note that you may experience compatibility problems if you mix a perl built
2106with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2107perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2108Some incompatibility may arise because of the bug fix that has been reverted
2109for VS2015 builds of perl, but there may well be incompatibility anyway because
fce64130 2110of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
bdd37d82 2111L<http://stackoverflow.com/questions/30412951>).
2c8edc25
S
2112
2113=back
2114
2115=item Win32
2116
2117=over 4
2118
2119=item *
2120
95b17558 2121Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2c8edc25 2122depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
95b17558 2123the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2c8edc25
S
2124
2125=item *
2126
2127fp definitions have been updated.
2128
2129=back
2130
2c8edc25
S
2131=item Linux
2132
2133Drop support for Linux a.out Linux has used ELF for over twenty years.
2134
2135=item OpenBSD 6
2136
2137OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2138Make sure this is accounted for.
2139
2140=item FreeBSD
2141
0f032fe1 2142F<t/uni/overload.t>: Skip hanging test on FreeBSD.
2c8edc25
S
2143
2144=back
2145
2146=head1 Internal Changes
2147
2148=over 4
2149
2150=item *
2151
0ebc1fcf
KW
2152A new API function L<C<sv_setpv_bufsize()>|perlapi/sv_setpv_bufsize>
2153allows simultaneously setting the
c2ef64b1
DM
2154length and allocated size of the buffer in an C<SV>, growing the buffer if
2155necessary.
2c8edc25
S
2156
2157=item *
2158
0ebc1fcf
KW
2159A new API macro L<C<SvPVCLEAR()>|perlapi/SvPVCLEAR> sets its C<SV>
2160argument to an empty string,
c2ef64b1 2161like Perl-space C<$x = ''>, but with several optimisations.
2c8edc25
S
2162
2163=item *
2164
c11f9206 2165Several new macros and functions for dealing with Unicode and
fb5d4b1a
KW
2166UTF-8-encoded strings have been added to the API, as well as some
2167changes in
c11f9206
DM
2168functionality of existing functions (see L<perlapi/Unicode Support> for
2169more details):
2170
2171=over
2172
2173=item *
2174
0ebc1fcf
KW
2175New versions of the API macros like C<isALPHA_utf8> and C<toLOWER_utf8>
2176have been added, each with the suffix C<_safe>, like
2177L<C<isSPACE_utf8_safe>|perlapi/isSPACE>. These take an extra
2178parameter, giving an upper
2179limit of how far into the string it is safe to read. Using the old
2180versions could cause attempts to read beyond the end of the input buffer
2181if the UTF-8 is not well-formed, and their use now raises a deprecation
2182warning. Details are at L<perlapi/Character classification>.
2c8edc25
S
2183
2184=item *
2185
0ebc1fcf
KW
2186Macros like L<C<isALPHA_utf8>|perlapi/isALPHA> and
2187L<C<toLOWER_utf8>|perlapi/toLOWER_utf8> now die if they detect
ac6c7175
KW
2188that their input UTF-8 is malformed. A deprecation warning had been
2189issued since Perl 5.18.
2c8edc25
S
2190
2191=item *
2192
c11f9206
DM
2193Several new macros for analysing the validity of utf8 sequences. These
2194are:
2195
bfe8fcbb
KW
2196L<C<UTF8_GOT_ABOVE_31_BIT>|perlapi/UTF8_GOT_ABOVE_31_BIT>
2197L<C<UTF8_GOT_CONTINUATION>|perlapi/UTF8_GOT_CONTINUATION>
2198L<C<UTF8_GOT_EMPTY>|perlapi/UTF8_GOT_EMPTY>
2199L<C<UTF8_GOT_LONG>|perlapi/UTF8_GOT_LONG>
2200L<C<UTF8_GOT_NONCHAR>|perlapi/UTF8_GOT_NONCHAR>
2201L<C<UTF8_GOT_NON_CONTINUATION>|perlapi/UTF8_GOT_NON_CONTINUATION>
2202L<C<UTF8_GOT_OVERFLOW>|perlapi/UTF8_GOT_OVERFLOW>
2203L<C<UTF8_GOT_SHORT>|perlapi/UTF8_GOT_SHORT>
2204L<C<UTF8_GOT_SUPER>|perlapi/UTF8_GOT_SUPER>
2205L<C<UTF8_GOT_SURROGATE>|perlapi/UTF8_GOT_SURROGATE>
2206L<C<UTF8_IS_INVARIANT>|perlapi/UTF8_IS_INVARIANT>
2207L<C<UTF8_IS_NONCHAR>|perlapi/UTF8_IS_NONCHAR>
2208L<C<UTF8_IS_SUPER>|perlapi/UTF8_IS_SUPER>
2209L<C<UTF8_IS_SURROGATE>|perlapi/UTF8_IS_SURROGATE>
2210L<C<UVCHR_IS_INVARIANT>|perlapi/UVCHR_IS_INVARIANT>
2211L<C<isUTF8_CHAR_flags>|perlapi/isUTF8_CHAR_flags>
2212L<C<isSTRICT_UTF8_CHAR>|perlapi/isSTRICT_UTF8_CHAR>
2213L<C<isC9_STRICT_UTF8_CHAR>|perlapi/isC9_STRICT_UTF8_CHAR>
2c8edc25
S
2214
2215=item *
2216
0f032fe1 2217Functions that are all extensions of the C<is_utf8_string_I<*>()> functions,
c11f9206
DM
2218that apply various restrictions to the UTF-8 recognized as valid:
2219
bfe8fcbb
KW
2220L<C<is_strict_utf8_string>|perlapi/is_strict_utf8_string>,
2221L<C<is_strict_utf8_string_loc>|perlapi/is_strict_utf8_string_loc>,
2222L<C<is_strict_utf8_string_loclen>|perlapi/is_strict_utf8_string_loclen>,
c11f9206 2223
bfe8fcbb
KW
2224L<C<is_c9strict_utf8_string>|perlapi/is_c9strict_utf8_string>,
2225L<C<is_c9strict_utf8_string_loc>|perlapi/is_c9strict_utf8_string_loc>,
2226L<C<is_c9strict_utf8_string_loclen>|perlapi/is_c9strict_utf8_string_loclen>,
c11f9206 2227
bfe8fcbb
KW
2228L<C<is_utf8_string_flags>|perlapi/is_utf8_string_flags>,
2229L<C<is_utf8_string_loc_flags>|perlapi/is_utf8_string_loc_flags>,
2230L<C<is_utf8_string_loclen_flags>|perlapi/is_utf8_string_loclen_flags>,
c11f9206 2231
bfe8fcbb
KW
2232L<C<is_utf8_fixed_width_buf_flags>|perlapi/is_utf8_fixed_width_buf_flags>,
2233L<C<is_utf8_fixed_width_buf_loc_flags>|perlapi/is_utf8_fixed_width_buf_loc_flags>,
2234L<C<is_utf8_fixed_width_buf_loclen_flags>|perlapi/is_utf8_fixed_width_buf_loclen_flags>.
c11f9206 2235
bfe8fcbb
KW
2236L<C<is_utf8_invariant_string>|perlapi/is_utf8_invariant_string>.
2237L<C<is_utf8_valid_partial_char>|perlapi/is_utf8_valid_partial_char>.
2238L<C<is_utf8_valid_partial_char_flags>|perlapi/is_utf8_valid_partial_char_flags>.
2c8edc25
S
2239
2240=item *
2241
bfe8fcbb
KW
2242The functions L<C<utf8n_to_uvchr>|perlapi/utf8n_to_uvchr> and its
2243derivatives have had several changes of behaviour.
c11f9206
DM
2244
2245Calling them, while passing a string length of 0 is now asserted against
2246in DEBUGGING builds, and otherwise returns the Unicode REPLACEMENT
2247CHARACTER. If you have nothing to decode, you shouldn't call the decode
2248function.
2249
2250They now return the Unicode REPLACEMENT CHARACTER if called with UTF-8
2251that has the overlong malformation, and that malformation is allowed by
2252the input parameters. This malformation is where the UTF-8 looks valid
2253syntactically, but there is a shorter sequence that yields the same code
2254point. This has been forbidden since Unicode version 3.1.
2255
2256They now accept an input
2c8edc25
S
2257flag to allow the overflow malformation. This malformation is when the
2258UTF-8 may be syntactically valid, but the code point it represents is
2259not capable of being represented in the word length on the platform.
2260What "allowed" means in this case is that the function doesn't return an
fb5d4b1a
KW
2261error, and it advances the parse pointer to beyond the UTF-8 in
2262question, but it returns the Unicode REPLACEMENT CHARACTER as the value
2263of the code point (since the real value is not representable).
2c8edc25 2264
55b0afa5
KW
2265They no longer abandon searching for other malformations when the first
2266one is encountered. A call to one of these functions thus can generate
2267multiple diagnostics, instead of just one.
2c8edc25
S
2268
2269=item *
2270
0ebc1fcf
KW
2271L<C<valid_utf8_to_uvchr()>|perlapi/valid_utf8_to_uvchr> has been added
2272to the API (although it was
c11f9206 2273present in core earlier). Like C<utf8_to_uvchr_buf()>, but assumes that
fb5d4b1a 2274the next character is well-formed. Use with caution.
c11f9206
DM
2275
2276=item *
2277
bfe8fcbb
KW
2278A new function, L<C<utf8n_to_uvchr_error>|perlapi/utf8n_to_uvchr_error>,
2279has been added for
2c8edc25
S
2280use by modules that need to know the details of UTF-8 malformations
2281beyond pass/fail. Previously, the only ways to know why a sequence was
2282ill-formed was to capture and parse the generated diagnostics, or to do
2283your own analysis.
2284
2285=item *
2286
0ebc1fcf
KW
2287There is now a safer version of utf8_hop(), called
2288L<C<utf8_hop_safe()>|perlapi/utf8_hop_safe>.
c11f9206
DM
2289Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or
2290after the end of the supplied buffer.
2c8edc25
S
2291
2292=item *
2293
0ebc1fcf
KW
2294Two new functions, L<C<utf8_hop_forward()>|perlapi/utf8_hop_forward> and
2295L<C<utf8_hop_back()>|perlapi/utf8_hop_back> are
c11f9206
DM
2296similar to C<utf8_hop_safe()> but are for when you know which direction
2297you wish to travel.
2c8edc25
S
2298
2299=item *
2300
c11f9206
DM
2301Two new macros which return useful utf8 byte sequences:
2302
bfe8fcbb
KW
2303L<C<BOM_UTF8>|perlapi/BOM_UTF8>
2304L<C<REPLACEMENT_CHARACTER_UTF8>|perlapi/REPLACEMENT_CHARACTER_UTF8>
c11f9206
DM
2305
2306=back
c2ef64b1
DM
2307
2308=item *
2309
2310Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
2311default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2312This flag alters how the C<op_sibling> field is used in C<OP> structures,
2313and has been available optionally since perl 5.22.
2314
2315See L<perl5220delta/"Internal Changes"> for more details of what this
2316build option does.
2317
2318=item *
2319
2320Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
2321been added. These are intended principally to implement the individual
2322elements of a subroutine signature, plus any overall checking required.
2323
2324=item *
2325
0ebc1fcf
KW
2326The L<C<op_class()>|perlapi/op_class> API function has been added. This
2327is like the existing
c2ef64b1
DM
2328C<OP_CLASS()> macro, but can more accurately determine what struct an op
2329has been allocated as. For example C<OP_CLASS()> might return
2330C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2331allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2332C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2c8edc25
S
2333
2334=item *
2335
2336All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2337previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2338that several parts of the internals had to be special-cased to accommodate
95b17558 2339it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2c8edc25
S
2340that is now handled in a simpler way.
2341
2342=item *
2343
0ebc1fcf
KW
2344The output format of the L<C<op_dump()>|perlapi/op_dump> function (as
2345used by C<perl -Dx>)
c2ef64b1
DM
2346has changed: it now displays an "ASCII-art" tree structure, and shows more
2347low-level details about each op, such as its address and class.
2c8edc25
S
2348
2349=item *
2350
c2ef64b1
DM
2351The C<PADOFFSET> type has changed from being unsigned to signed, and
2352several pad-related variables such as C<PL_padix> have changed from being
2353of type C<I32> to type C<PADOFFSET>.
2c8edc25
S
2354
2355=item *
2356
c2ef64b1
DM
2357The C<DEBUGGING>-mode output for regex compilation and execution has been
2358enhanced.
2c8edc25
S
2359
2360=item *
2361
74ca8c9e
DM
2362Several obscure SV flags have been eliminated, sometimes along with the
2363macros which manipulate them: C<SVpbm_VALID>, C<SVpbm_TAIL>, C<SvTAIL_on>,
2364C<SvTAIL_off>, C<SVrepl_EVAL>, C<SvEVALED>
2c8edc25
S
2365
2366=item *
2367
74ca8c9e
DM
2368An OP op_private flag has been eliminated: C<OPpRUNTIME>. This used to
2369often get set on C<PMOP>s, but had become meaningless over time.
2c8edc25
S
2370
2371=back
2372
2373=head1 Selected Bug Fixes
2374
2375=over 4
2376
2377=item *
2378
5573eafe
DM
2379Perl no longer panics when switching into some locales on machines with
2380buggy C<strxfrm()> implementations in their libc. [perl #121734]
2381
2382=item *
2383
2c8edc25
S
2384C< $-{$name} > would leak an C<AV> on each access if the regular
2385expression had no named captures. The same applies to access to any
2386hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2387#130822]
2388
2389=item *
2390
2391Attempting to use the deprecated variable C<$#> as the object in an
2392indirect object method call could cause a heap use after free or
2393buffer overflow. [perl #129274]
2394
2395=item *
2396
2397When checking for an indirect object method call in some rare cases
2398the parser could reallocate the line buffer but then continue to use
2399pointers to the old buffer. [perl #129190]
2400
2401=item *
2402
0f032fe1
KW
2403Supplying a glob as the format argument to
2404L<C<formline>|perlfunc/formline> would
2c8edc25
S
2405cause an assertion failure. [perl #130722]
2406
2407=item *
2408
2409Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
0f032fe1 2410converted into a C<qr//> operator, leaving extra elements on the stack to
2c8edc25
S
2411confuse any surrounding expression. [perl #130705]
2412
2413=item *
2414
d3972b39 2415Since v5.24 in some obscure cases, a regex which included code blocks
0f032fe1 2416from multiple sources (I<e.g.>, via embedded via C<qr//> objects) could end up
2c8edc25
S
2417with the wrong current pad and crash or give weird results. [perl #129881]
2418
2419=item *
2420
2421Occasionally C<local()>s in a code block within a patterns weren't being
2422undone when the pattern matching backtracked over the code block.
2423[perl #126697]
2424
2425=item *
2426
2427Using C<substr()> to modify a magic variable could access freed memory
2428in some cases. [perl #129340]
2429
2430=item *
2431
2c8edc25 2432Under C<use utf8>, the entire Perl program is now checked that the UTF-8
fb5d4b1a 2433is wellformed. [perl #126310].
2c8edc25
S
2434
2435=item *
2436
df48f9a4 2437The range operator C<".."> on strings now handles its arguments correctly when in
2c8edc25 2438the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
95b17558 2439feature. The previous behaviour was sufficiently unexpected that we believe no
2c8edc25
S
2440correct program could have made use of it.
2441
2442=item *
2443
0f032fe1 2444The C<split> operator did not ensure enough space was allocated for
2c8edc25
S
2445its return value in scalar context. It could then write a single
2446pointer immediately beyond the end of the memory block allocated for
2447the stack. [perl #130262]
2448
2449=item *
2450
df48f9a4 2451Using a large code point with the C<"W"> pack template character with
2c8edc25
S
2452the current output position aligned at just the right point could
2453cause a write a single zero byte immediately beyond the end of an
2454allocated buffer. [perl #129149]
2455
2456=item *
2457
2458Supplying the form picture argument as part of the form argument list
2459where the picture specifies modifying the argument could cause an
2460access to the new freed compiled form. [perl #129125]
2461
2462=item *
2463
2464Fix a problem with sort's build-in compare, where it would not sort
2465correctly with 64-bit integers, and non-long doubles. [perl #130335]
2466
2467=item *
2468
0ebc1fcf
KW
2469Fix issues with C</(?{ ... E<lt>E<lt>EOF })/> that broke
2470L<Method::Signatures>. [perl #130398]
2c8edc25
S
2471
2472=item *
2473
2c8edc25
S
2474Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2475
2476=item *
2477
2478Fixed an assertion failure with C<chop> and C<chomp>, which
2479could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2480
2481=item *
2482
fb5d4b1a
KW
2483Fixed a comment skipping error in patterns under C</x>; it could stop
2484skipping a byte early, which could be in the middle of a UTF-8
2485character. [perl #130495].
2c8edc25
S
2486
2487=item *
2488
2489F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2490
2491=item *
2492
2493Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2494
2495=item *
2496
0f032fe1 2497DragonFly BSD now has support for C<setproctitle()>. [perl #130068].
2c8edc25
S
2498
2499=item *
2500
fb5d4b1a 2501Fix an assertion error which could be triggered when a lookahead string
2c8edc25
S
2502in patterns exceeded a minimum length. [perl #130522].
2503
2504=item *
2505
df48f9a4 2506Only warn once per literal about a misplaced C<"_">. [perl #70878].
2c8edc25
S
2507
2508=item *
2509
2510Ensure range-start is set after error in C<tr///>. [perl #129342].
2511
2512=item *
2513
2514Don't read past start of string for unmatched backref; otherwise,
2515we may have heap buffer overflow. [perl #129377].
2516
2517=item *
2518
2c8edc25 2519C<use re 'strict'> is supposed to warn if you use a range whose start
95b17558 2520and end digit aren't from the same group of 10. It didn't do that
2c8edc25
S
2521for five groups of mathematical digits starting at U+1D7E.
2522
2523=item *
2524
fce64130 2525A sub containing a "forward" declaration with the same name (I<e.g.>,
2c8edc25
S
2526C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2527#129090]
2528
2529=item *
2530
fb5d4b1a 2531A crash in executing a regex with a non-anchored UTF-8 substring against a
2c8edc25
S
2532target string that also used UTF-8 has been fixed. [perl #129350]
2533
2534=item *
2535
2536Previously, a shebang line like C<#!perl -i u> could be erroneously
95b17558 2537interpreted as requesting the C<-u> option. This has been fixed. [perl
2c8edc25
S
2538#129336]
2539
2540=item *
2541
2542The regex engine was previously producing incorrect results in some rare
2543situations when backtracking past a trie that matches only one thing; this
0f032fe1 2544showed up as capture buffers (C<$1>, C<$2>, I<etc.>) erroneously containing data
2c8edc25
S
2545from regex execution paths that weren't actually executed for the final
2546match. [perl #129897]
2547
2548=item *
2549
2550Certain regexes making use of the experimental C<regex_sets> feature could
95b17558 2551trigger an assertion failure. This has been fixed. [perl #129322]
2c8edc25
S
2552
2553=item *
2554
fce64130 2555Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
2c8edc25
S
2556sometimes crash in addition to giving a syntax error. [perl #125679]
2557
2558=item *
2559
2560The parser could sometimes crash if a bareword came after C<evalbytes>.
2561[perl #129196]
2562
2563=item *
2564
2565Autoloading via a method call would warn erroneously ("Use of inherited
2566AUTOLOAD for non-method") if there was a stub present in the package into
2567which the invocant had been blessed. The warning is no longer emitted in
2568such circumstances. [perl #47047]
2569
2570=item *
2571
2c8edc25
S
2572The use of C<splice> on arrays with nonexistent elements could cause other
2573operators to crash. [perl #129164]
2574
2575=item *
2576
2577Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2578string. [perl #129012]
2579
2580=item *
2581
2582Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2583checking that the I<current> C<cx> is the right type, and instead was always
2584checking the base C<cx> (effectively a noop). [perl #129029]
2585
2586=item *
2587
95b17558 2588Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2c8edc25
S
2589maintains up to two pointers into the parser buffer, one of which can
2590become stale under the right conditions. [perl #129069]
2591
2592=item *
2593
2594Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2595when it wasn't. [perl #129038]
2596
2597=item *
2598
2599Fixed place where regex was not setting the syntax error correctly.
2600[perl #129122]
2601
2602=item *
2603
df48f9a4 2604The C<&.> operator (and the C<"&"> operator, when it treats its arguments as
2c8edc25
S
2605strings) were failing to append a trailing null byte if at least one string
2606was marked as utf8 internally. Many code paths (system calls, regexp
2607compilation) still expect there to be a null byte in the string buffer
2608just past the end of the logical string. An assertion failure was the
2609result. [perl #129287]
2610
2611=item *
2612
2613Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2614silently truncates the supplied path if it won't fit into the C<sun_path>
95b17558 2615member of C<sockaddr_un>. This may change in the future, but for now
2c8edc25
S
2616check the path in theC<sockaddr> matches the desired path, and skip if
2617it doesn't. [perl #128095]
2618
2619=item *
2620
95b17558 2621Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2c8edc25
S
2622cases this is used in building error messages. [perl #128988]
2623
2624=item *
2625
570ce26a
KW
2626Fix segfault when run with C<-DC> options on DEBUGGING builds.
2627[perl #129106]
2c8edc25
S
2628
2629=item *
2630
2631Fixed the parser error handling for an 'C<:attr(foo>' that does not have
df48f9a4 2632an ending 'C<")">'.
2c8edc25
S
2633
2634=item *
2635
2636Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2637actually fixed two bugs, [perl #129064] and [perl #129176].
2638
2639=item *
2640
0f032fe1
KW
2641[perl #129267] rework C<gv_fetchmethod_pvn_flags> separator parsing to
2642prevent possible string overrun with invalid len in F<gv.c>
2c8edc25
S
2643
2644=item *
2645
2646Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2647where the source and destination of the sort are the same plain array, are
95b17558 2648optimised to do less copying around. Two side-effects of this optimisation
2c8edc25
S
2649were that the contents of C<@a> as visible to to sort routine were
2650partially sorted, and under some circumstances accessing C<@a> during the
95b17558 2651sort could crash the interpreter. Both these issues have been fixed, and
2c8edc25
S
2652Sort functions see the original value of C<@a>.
2653
2654=item *
2655
2656Non-ASCII string delimiters are now reported correctly in error messages
2657for unterminated strings. [perl #128701]
2658
2659=item *
2660
2661C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2662temporary value") erroneously in some cases, but has been fixed.
2663
2664=item *
2665
2666C<@DB::args> is now exempt from "used once" warnings. The warnings only
2667occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2668multiple times.
2669
2670=item *
2671
2672The use of built-in arrays or hash slices in a double-quoted string no
2673longer issues a warning ("Possible unintended interpolation...") if the
2674variable has not been mentioned before. This affected code like
2675C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2676C<@-> and C<@+> were already exempt from the warning.)
2677
2678=item *
2679
2680C<gethostent> and similar functions now perform a null check internally, to
d3972b39 2681avoid crashing with torsocks. This was a regression from v5.22. [perl
2c8edc25
S
2682#128740]
2683
2684=item *
2685
2686C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2687memory if the typeglob in question has never been accessed before.
2688
2689=item *
2690
2c8edc25
S
2691Mentioning the same constant twice in a row (which is a syntax error) no
2692longer fails an assertion under debugging builds. This was a regression
d3972b39 2693from v5.20. [perl #126482]
2c8edc25
S
2694
2695=item *
2696
2697Many issues relating to C<printf "%a"> of hexadecimal floating point
2698were fixed. In addition, the "subnormals" (formerly known as "denormals")
fb5d4b1a 2699floating point numbers are now supported both with the plain IEEE 754
2c8edc25
S
2700floating point numbers (64-bit or 128-bit) and the x86 80-bit
2701"extended precision". Note that subnormal hexadecimal floating
2702point literals will give a warning about "exponent underflow".
2703[perl #128843, #128889, #128890, #128893, #128909, #128919]
2704
2705=item *
2706
d3972b39 2707A regression in v5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2c8edc25
S
2708128 and 255 has been fixed. [perl #128734].
2709
2710=item *
2711
2c8edc25
S
2712Use of a string delimiter whose code point is above 2**31 now works
2713correctly on platforms that allow this. Previously, certain characters,
2714due to truncation, would be confused with other delimiter characters
df48f9a4 2715with special meaning (such as C<"?"> in C<m?...?>), resulting
2c8edc25
S
2716in inconsistent behaviour. Note that this is non-portable,
2717and is based on Perl's extension to UTF-8, and is probably not
2718displayable nor enterable by any editor. [perl #128738]
2719
2720=item *
2721
df48f9a4 2722C<@{x> followed by a newline where C<"x"> represents a control or non-ASCII
2c8edc25
S
2723character no longer produces a garbled syntax error message or a crash.
2724[perl #128951]
2725
2726=item *
2727
2728An assertion failure with C<%: = 0> has been fixed.
2729L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2730
2731=item *
2732
2733In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2734that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2735was to parse it as C<$foo:: . $bar>, has been restored.
2736L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2737
2738=item *
2739
2740Since Perl 5.20, line numbers have been off by one when perl is invoked with
2741the B<-x> switch. This has been fixed.
2742L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2743
2744=item *
2745
fce64130 2746Vivifying a subroutine stub in a deleted stash (I<e.g.>, C<delete $My::{"Foo::"};
2c8edc25
S
2747\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2748L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2749
2750=item *
2751
2752Some obscure cases of subroutines and file handles being freed at the same time
2753could result in crashes, but have been fixed. The crash was introduced in Perl
27545.22.
2755L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2756
2757=item *
2758
2759Code that looks for a variable name associated with an uninitialized value
fb5d4b1a 2760could cause an assertion failure in cases where magic is involved, such as
2c8edc25
S
2761C<$ISA[0][0]>. This has now been fixed.
2762L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2763
2764=item *
2765
2766A crash caused by code generating the warning "Subroutine STASH::NAME
2767redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2768fixed. In these cases, where the STASH is missing, the warning will now appear
2769as "Subroutine NAME redefined".
2770L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2771
2772=item *
2773
2774Fixed an assertion triggered by some code that handles deprecated behavior in
fce64130 2775formats, I<e.g.>, in cases like this:
2c8edc25
S
2776
2777 format STDOUT =
2778 @
2779 0"$x"
2780
2781L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2782
2783=item *
2784
2785A possible divide by zero in string transformation code on Windows has been
2786avoided, fixing a crash when collating an empty string.
2787L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2788
2789=item *
2790
2791Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2792regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2793L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2794
2795=item *
2796
2797C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2798warn when syntax warnings are enabled. [perl #127333]
2799
2800=item *
2801
2802socket() now leaves the error code returned by the system in C<$!> on
2803failure. [perl #128316]
2804
2805=item *
2806
2807Assignment variants of any bitwise ops under the C<bitwise> feature would
2808crash if the left-hand side was an array or hash. [perl #128204]
2809
2810=item *
2811
2812C<require> followed by a single colon (as in C<foo() ? require : ...> is
0f032fe1 2813now parsed correctly as C<require> with implicit C<$_>, rather than
2c8edc25
S
2814C<require "">. [perl #128307]
2815
2816=item *
2817
2818Scalar C<keys %hash> can now be assigned to consistently in all scalar
2819lvalue contexts. Previously it worked for some contexts but not others.
2820
2821=item *
2822
2823List assignment to C<vec> or C<substr> with an array or hash for its first
2824argument used to result in crashes or "Can't coerce" error messages at run
2825time, unlike scalar assignment, which would give an error at compile time.
2826List assignment now gives a compile-time error, too. [perl #128260]
2827
2828=item *
2829
2830Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
95b17558 2831and C<or>) were being compiled incorrectly in some cases. If the left-hand
2c8edc25
S
2832side consisted of either a negated bareword constant or a negated C<do {}>
2833block containing a constant expression, and the right-hand side consisted of
2834a negated non-foldable expression, one of the negations was effectively
95b17558
KW
2835ignored. The same was true of C<if> and C<unless> statement modifiers,
2836though with the left-hand and right-hand sides swapped. This long-standing
2c8edc25
S
2837bug has now been fixed. [perl #127952]
2838
2839=item *
2840
2841C<reset> with an argument no longer crashes when encountering stash entries
2842other than globs. [perl #128106]
2843
2844=item *
2845
2846Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2847longer causes crashes. [perl #128086]
2848
2849=item *
2850
0f032fe1 2851Handle C<SvIMMORTALs> in LHS of list assign. [perl #129991]
2c8edc25
S
2852
2853=item *
2854
fc751fe1 2855Assertion failure with user-defined Unicode-like properties. [perl #130010]
2c8edc25
S
2856
2857=item *
2858
2859Fix error message for unclosed C<\N{> in regcomp.
2860
2861An unclosed C<\N{> could give the wrong error message
2862C<"\N{NAME} must be resolved by the lexer">.
2863
2864=item *
2865
2866List assignment in list context where the LHS contained aggregates and
2867where there were not enough RHS elements, used to skip scalar lvalues.
2868Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
95b17558
KW
2869it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2870returns C<($a,$b,$c)>. This can be seen in the following:
2c8edc25
S
2871
2872 sub inc { $_++ for @_ }
2873 inc(($a,$b,@c,$d) = (10))
2874
2875Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2876now they are C<(11,1,1)>.
2877
2878=item *
2879
f632cffa
KW
2880Code like this: C</(?{ s!!! })/> can trigger infinite recursion on the C
2881stack (not the normal perl stack) when the last successful pattern in
2882scope is itself. We avoid the segfault by simply forbidding the use of
2883the empty pattern when it would resolve to the currently executing
5d7d637c 2884pattern. [perl #129903]
2c8edc25
S
2885
2886=item *
2887
0c092f6b 2888Avoid reading beyond the end of the line buffer when there's a
5d7d637c 2889short UTF-8 character at the end. [perl #128997]
2c8edc25
S
2890
2891=item *
2892
5d7d637c 2893Fix firstchar bitmap under utf8 with prefix optimisation. [perl #129950]
2c8edc25
S
2894
2895=item *
2896
5d7d637c 2897Make F<Carp/t/arg_string.t>: be liberal in C<f>/C<p> formats. [perl #129954]
2c8edc25
S
2898
2899=item *
2900
5d7d637c 2901Make C<do "a\0b"> fail silently instead of throwing an error. [perl #129928]
2c8edc25
S
2902
2903=item *
2904
5d7d637c 2905Make C<chdir> allocate the stack it needs. [perl #129130]
2c8edc25 2906
acea3104
KW
2907=item *
2908
2909C<do> errors now refer to C<do> (not C<require>).
2910
2911=item *
2912
2913Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
2914blames the variable for an uninitialized-value warning encountered by the
2915tied/magical code.
2916
2917=item *
2918
2919Code like C<$x = $x . "a"> was incorrectly failing to yield a
2920L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
2921warning when C<$x> was a lexical variable with an undefined value. That has
2922now been fixed. [perl #127877]
2923
2924=item *
2925
2926C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
2927argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
2928been fixed.
2929
2930=item *
2931
2932C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
2933string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
2934bringing it into consistency with C<$$scalar>.
2935
2936=item *
2937
2938C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
2939do, but merely produce a syntax error. [perl #128171]
2940
2941=item *
2942
2943C<do> or C<require> with a reference or typeglob which, when stringified,
2944contains a null character started crashing in Perl 5.20, but has now been
2945fixed. [perl #128182]
2946
2947=item *
2948
2949Improve error for missing C<tie()> package/method. This brings the error messages
2950in line with the ones used for normal method calls, despite not using
2951call_method().
2952
2c8edc25
S
2953=back
2954
2955=head1 Known Problems
2956
2957=over 4
2958
2959=item *
2960
2961Some modules have been broken by the L<context stack rework|/Internal Changes>.
fb5d4b1a
KW
2962These modules were relying on non-guaranteed implementation details in
2963the perl interpreter.
2c8edc25
S
2964Their maintainers have been informed, and should contact perl5-porters for
2965advice if needed. Below is a subset of these modules:
2966
2967=over 4
2968
2969=item * L<Algorithm::Permute>
2970
2971=item * L<Coro>
2972
fb5d4b1a
KW
2973L<Coro> and Perl 5.22 were already incompatible due to a change in the perl
2974interpreter,
2c8edc25
S
2975and the reworking on the perl context stack creates a further incompatibility.
2976perl5-porters has L<discussed the issue on the mailing
2977list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
2978
2979=item * L<Data::Alias>
2980
2981=item * L<RPerl>
2982
2983=item * L<Scope::Upper>
2984
2985=item * L<TryCatch>
2986
2987=back
2988
2989=item *
2990
53799a91 2991The module L<lexical::underscore> no longer works on Perl 5.24, because perl
2c8edc25
S
2992no longer has a lexical C<$_>!
2993
2994=item *
2995
53799a91 2996C<mod_perl> has been patched for compatibility for v5.22 and later but no
2c8edc25
S
2997release has been made. The relevant patch (and other changes) can be found in
2998their source code repository, L<mirrored at
2999GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
3000
3001=back
3002
3003=head1 Errata From Previous Releases
3004
3005=over 4
3006
3007=item *
3008
ee8180b8 3009Parsing bad POSIX charclasses no longer leaks memory.
2c8edc25
S
3010L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
3011
3012=item *
3013
53799a91 3014Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
2c8edc25
S
3015L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
3016
3017=back
3018
3019=head1 Obituary
3020
3021Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
95b17558 3022member, has passed away on August 10, 2016. He will be remembered and
c94c0e4f 3023missed by all those who he came in contact with, and enriched with his
2c8edc25
S
3024intellect, wit, and spirit.
3025
c94c0e4f 3026It is with great sadness that we also note Kip Hampton's passing. Probably
2c8edc25
S
3027best known as the author of the Perl & XML column on XML.com, he was a
3028core contributor to AxKit, an XML server platform that became an Apache
95b17558
KW
3029Foundation project. He was a frequent speaker in the early days at
3030OSCON, and most recently at YAPC::NA in Madison. He was frequently on
2c8edc25
S
3031irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
3032group responsible for YAPC::NA Asheville in 2011.
a049258c 3033
2c8edc25
S
3034Kip and his constant contributions to the community will be greatly
3035missed.
a049258c
S
3036
3037=head1 Acknowledgements
2e0dcc12 3038
0cc8c746 3039Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 3040and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
S
3041authors.
3042
3043Excluding auto-generated files, documentation and release tools, there were
3044approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
3045
3046Perl continues to flourish into its third decade thanks to a vibrant community
95b17558 3047of users and developers. The following people are known to have contributed the
ad543fb2 3048improvements that became Perl 5.26.0:
0cc8c746
S
3049
3050Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
3051König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
3052Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
3053Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
3054Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
3055Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3056Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3057Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3058D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3059Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3060De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3061Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3062Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3063Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3064Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3065Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3066Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3067Yves Orton, Zefram.
0cc8c746
S
3068
3069The list above is almost certainly incomplete as it is automatically generated
95b17558 3070from version control history. In particular, it does not include the names of
0cc8c746
S
3071the (very much appreciated) contributors who reported issues to the Perl bug
3072tracker.
3073
3074Many of the changes included in this version originated in the CPAN modules
95b17558 3075included in Perl's core. We're grateful to the entire CPAN community for
0cc8c746
S
3076helping Perl to flourish.
3077
3078For a more complete list of all of Perl's historical contributors, please see
3079the F<AUTHORS> file in the Perl source distribution.
f5b73711 3080
44691e6f
AB
3081=head1 Reporting Bugs
3082
2c8edc25
S
3083If you find what you think is a bug, you might check the articles recently
3084posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3085L<https://rt.perl.org/> . There may also be information at
4b8803f0 3086L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3087
e08634c5
SH
3088If you believe you have an unreported bug, please run the L<perlbug> program
3089included with your release. Be sure to trim your bug down to a tiny but
3090sufficient test case. Your bug report, along with the output of C<perl -V>,
7c825fca 3091will be sent off to C<perlbug@perl.org> to be analysed by the Perl porting team.
44691e6f 3092
87c118b9
DM
3093If the bug you are reporting has security implications which make it
3094inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3095L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3096for details of how to report the issue.
44691e6f
AB
3097
3098=head1 SEE ALSO
3099
e08634c5
SH
3100The F<Changes> file for an explanation of how to view exhaustive details on
3101what changed.
44691e6f
AB
3102
3103The F<INSTALL> file for how to build Perl.
3104
3105The F<README> file for general stuff.
3106
3107The F<Artistic> and F<Copying> files for copyright information.
3108
3109=cut