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perldelta: Fix some issues raised by Ævar
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1=encoding utf8
2
3=head1 NAME
4
2c8edc25 5perldelta - what is new for perl v5.26.0
eabfc7bc 6
2cfe9b50 7=head1 DESCRIPTION
eabfc7bc 8
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9This document describes the differences between the 5.24.0 release and the
105.26.0 release.
11
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12=head1 Notice
13
16beba24 14This release includes three updates with widespread effects:
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15
16=over 4
17
18=item * C<.> no longer in C<@INC>
19
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20For security reasons, the current directory (C<.>) is no longer included
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
24L<< Removal of the current directory (C<.>) from C<@INC> >>
25for the full details.
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26
27=item * C<do> may now warn
28
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29C<do> now gives a deprecation warning when it fails to load a file which
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
2c8edc25 41=head2 New regular expression modifier C</xx>
f4b40f11 42
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43Specifying two C<x> characters to modify a regular expression pattern
44does everything that a single one does, but additionally TAB and SPACE
45characters within a bracketed character class are generally ignored and
46can be added to improve readability, like
47S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
48L<perlre/E<sol>x and E<sol>xx>.
5e50eae4 49
2c8edc25 50=head2 New Hash Function For 64-bit Builds
a049258c 51
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52We have switched to a hybrid hash function to better balance
53performance for short and long keys.
54
55For short keys, 16 bytes and under, we use an optimised variant of
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56One At A Time Hard, and for longer keys we use Siphash 1-3. For very
57long keys this is a big improvement in performance. For shorter keys
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58there is a modest improvement.
59
60=head2 Indented Here-documents
61
62This adds a new modifier '~' to here-docs that tells the parser
63that it should look for /^\s*$DELIM\n/ as the closing delimiter.
64
65These syntaxes are all supported:
66
67 <<~EOF;
68 <<~\EOF;
69 <<~'EOF';
70 <<~"EOF";
71 <<~`EOF`;
72 <<~ 'EOF';
73 <<~ "EOF";
74 <<~ `EOF`;
75
76The '~' modifier will strip, from each line in the here-doc, the
77same whitespace that appears before the delimiter.
78
fce64130 79Newlines will be copied as-is, and lines that don't include the
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80proper beginning whitespace will cause perl to croak.
81
82For example:
83
84 if (1) {
85 print <<~EOF;
86 Hello there
87 EOF
88 }
89
90prints "Hello there\n" with no leading whitespace.
91
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92=head2 @{^CAPTURE}, %{^CAPTURE}, and %{^CAPTURE_ALL}
93
94C<@{^CAPTURE}> exposes the capture buffers of the last match as an
95b17558 95array. So C<$1> is C<${^CAPTURE}[0]>. This is a more efficient equivalent
95013431 96to code like C<substr($matched_string,$-[0],$+[0]-$-[0])>, and you don't
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97have to keep track of the C<$matched_string> either. This variable has no
98single character equivalent. Note, like the other regex magic variables
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99the contents of this variable is dynamic, if you wish to store it beyond
100the lifetime of the match you must copy it to another array.
2c8edc25 101
95b17558 102C<%{^CAPTURE}> is the equivalent to C<%+> (I<i.e.>, named captures). Other than
95013431 103being more self documenting there is no difference between the two forms.
2c8edc25 104
fce64130 105C<%{^CAPTURE_ALL}> is the equivalent to C<%-> (I<i.e.>, all named captures).
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106Other than being more self documenting there is no difference between the
107two forms.
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108
109=head2 Unicode 9.0 is now supported
110
111A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
112Modules that are shipped with core Perl but not maintained by p5p do not
113necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
114
115=head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
116
117Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and
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118called it Script_Extensions (C<scx>). Perl now uses this improved
119version when a property is specified as just C<\p{I<script>}>. This
120should make programs be more accurate when determining if a character is
121used in a given script, but there is a slight chance of breakage for
122programs that very specifically needed the old behavior. The meaning of
123compound forms, like C<\p{sc=I<script>}> are unchanged. See
124L<perlunicode/Scripts>.
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125
126=head2 Declaring a reference to a variable
127
128As an experimental feature, Perl now allows the referencing operator to come
129after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
130L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
131be enabled with C<use feature 'declared_refs'>. It is experimental, and will
132warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
133It is intended mainly for use in assignments to references. For example:
134
135 use experimental 'refaliasing', 'declared_refs';
136 my \$a = \$b;
137
a9fbda47 138See L<perlref/Assigning to References> for more details.
a049258c 139
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140=head2 Perl can now do default collation in UTF-8 locales on platforms
141that support it
a049258c 142
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143Some platforms natively do a reasonable job of collating and sorting in
144UTF-8 locales. Perl now works with those. For portability and full
145control, L<Unicode::Collate> is still recommended, but now you may
146not need to do anything special to get good-enough results, depending on
147your application. See
148L<perllocale/Category C<LC_COLLATE>: Collation: Text Comparisons and Sorting>.
149
150=head2 Better locale collation of strings containing embedded C<NUL>
151characters
152
fce64130 153In locales that have multi-level character weights, C<NUL>s are now
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154ignored at the higher priority ones. There are still some gotchas in
155some strings, though. See
156L<perllocale/Collation of strings containing embedded C<NUL> characters>.
157
158=head2 Lexical subroutines are no longer experimental
159
95b17558 160Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
2c8edc25 161code that disables the C<experimental::lexical_subs> warning category
95b17558 162that the feature previously used will continue to work. The
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163C<lexical_subs> feature has no effect; all Perl code can use lexical
164subroutines, regardless of what feature declarations are in scope.
165
166=head2 C<CORE> subroutines for hash and array functions callable via
167reference
168
169The hash and array functions in the C<CORE> namespace--C<keys>, C<each>,
170C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>--, can now
171be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference
e6abae1c 172(C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be
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173used when inlined.
174
8b70433f 175=head2 for XS code, create a safer utf8_hop() called utf8_hop_safe()
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176
177Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after
178the end of the supplied buffer.
179
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180=head1 Security
181
89853d76 182=head2 Removal of the current directory (C<.>) from C<@INC>
2c8edc25 183
95b17558 184The perl binary includes a default set of paths in C<@INC>. Historically
89853d76 185it has also included the current directory (C<.>) as the final entry,
95b17558 186unless run with taint mode enabled (C<perl -T>). While convenient, this has
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187security implications: for example, where a script attempts to load an
188optional module when its current directory is untrusted (such as F</tmp>),
189it could load and execute code from under that directory.
190
53799a91 191Starting with v5.26, C<.> is always removed by default, not just under
95b17558 192tainting. This has major implications for installing modules and executing
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193scripts.
194
195The following new features have been added to help ameliorate these
196issues.
197
198=over
199
200=item * C<Configure -Udefault_inc_excludes_dot>
201
202There is a new C<Configure> option, C<default_inc_excludes_dot> (enabled
203by default) which builds a perl executable without C<.>; unsetting this
95b17558 204option using C<-U> reverts perl to the old behaviour. This may fix your
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205path issues but will reintroduce all the security concerns, so don't
206build a perl executable like this unless you're I<really> confident that
207such issues are not a concern in your environment.
208
409c12ef 209=item * C<PERL_USE_UNSAFE_INC>
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210
211There is a new environment variable recognised by the perl interpreter.
212If this variable has the value C<1> when the perl interpreter starts up,
213then C<.> will be automatically appended to C<@INC> (except under tainting).
214
215This allows you restore the old perl interpreter behaviour on a
95b17558 216case-by-case basis. But note that this is intended to be a temporary crutch,
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217and this feature will likely be removed in some future perl version.
218It is currently set by the C<cpan> utility and C<Test::Harness> to
fce64130 219ease installation of CPAN modules which have not been updated to handle the
95b17558 220lack of dot. Once again, don't use this unless you are sure that this
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221will not reintroduce any security concerns.
222
223=item * A new mandatory warning issued by C<do>.
224
225While it is well-known that C<use> and C<require> use C<@INC> to search
226for the file to load, many people don't realise that C<do "file"> also
95b17558 227searches C<@INC> if the file is a relative path. With the removal of C<.>,
89853d76 228a simple C<do "file.pl"> will fail to read in and execute C<file.pl> from
95b17558 229the current directory. Since this is commonly expected behaviour, a new
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230mandatory warning is now issued whenever C<do> fails to load a file which
231it otherwise would have found if dot had been in C<@INC>.
232
233=back
234
235Here are some things script and module authors may need to do to make
236their software work in the new regime.
237
238=over
239
240=item * Script authors
241
242If the issue is within your own code (rather than within included
95b17558 243modules), then you have two main options. Firstly, if you are confident
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244that your script will only be run within a trusted directory (under which
245you expect to find trusted files and modules), then add C<.> back into the
fce64130 246path; I<e.g.>:
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247
248 BEGIN {
249 my $dir = "/some/trusted/directory";
250 chdir $dir or die "Can't chdir to $dir: $!\n";
251 # safe now
252 push @INC, '.';
253 }
254 use "Foo::Bar"; # may load /some/trusted/directory/Foo/Bar.pm
255 do "config.pl"; # may load /some/trusted/directory/config.pl
256
257On the other hand, if your script is intended to be run from within
258untrusted directories (such as F</tmp>), then your script suddenly failing
95b17558 259to load files may be indicative of a security issue. You most likely want
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260to replace any relative paths with full paths; for example,
261
262 do ".foo_config.pl"
263
264might become
265
266 do "$ENV{HOME}/.foo_config.pl"
267
268If you are absolutely certain that you want your script to load and
269execute a file from the current directory, then use a C<./> prefix; for
270example:
271
272 do "./.foo_config.pl"
273
274=item * Installing and using CPAN modules
275
276If you install a CPAN module using an automatic tool like C<cpan>, then
277this tool will itself set the C<PERL_USE_UNSAFE_INC> environment variable
278while building and testing the module, which may be sufficient to install
279a distribution which hasn't been updated to be dot-aware. If you want to
280install such a module manually, then you'll need to replace the
281traditional invocation:
282
283 perl Makefile.PL && make && make test && make install
284
285with something like
286
287 (export PERL_USE_UNSAFE_INC=1; \
288 perl Makefile.PL && make && make test && make install)
289
95b17558 290Note that this only helps build and install an unfixed module. It's
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291possible for the tests to pass (since they were run under
292C<PERL_USE_UNSAFE_INC=1>), but for the module itself to fail to perform
95b17558 293correctly in production. In this case you may have to temporarily modify
0f275d26 294your script until such time as a fixed version of the module is released.
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295For example:
296
297 use Foo::Bar;
298 {
299 local @INC = (@INC, '.');
300 # assuming read_config() needs '.' in @INC
301 $config = Foo::Bar->read_config();
302 }
303
95b17558 304This is only rarely expected to be necessary. Again, if doing this,
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305assess the resultant risks first.
306
307=item * Module Authors
308
309If you maintain a CPAN distribution, it may need updating to run in
95b17558 310a dotless environment. Although C<cpan> and other such tools will
0f275d26 311currently set the C<PERL_USE_UNSAFE_INC> during module build, this is a
89853d76 312temporary workaround for the set of modules which rely on C<.> being in
95b17558 313C<@INC> for installation and testing, and this may mask deeper issues. It
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314could result in a module which passes tests and installs, but which
315fails at run time.
316
317During build, test and install, it will normally be the case that any perl
318processes will be executing directly within the root directory of the
95b17558 319untarred distribution, or a known subdirectory of that, such as F<t/>. It
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320may well be that F<Makefile.PL> or F<t/foo.t> will attempt to include
321local modules and configuration files using their direct relative
322filenames, which will now fail.
323
324However, as described above, automatic tools like F<cpan> will (for now)
325set the C<PERL_USE_UNSAFE_INC> environment variable, which introduces
326dot during build.
327
328This makes it likely that your existing build and test code will work, but
329this may mask issues with your code which only manifest when used after
95b17558 330install. It is prudent to try and run your build process with that
89853d76 331variable explicitly disabled:
0f275d26 332
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333 (export PERL_USE_UNSAFE_INC=0; \
334 perl Makefile.PL && make && make test && make install)
335
336This is more likely to show up any potential problems with your module's
95b17558 337build process, or even with the module itself. Fixing such issues will
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338ensure both that your module can again be installed manually, and that
339it will still build once the C<PERL_USE_UNSAFE_INC> crutch goes away.
340
341When fixing issues in tests due to the removal of dot from C<@INC>,
342reinsertion of dot into C<@INC> should be performed with caution, for this
95b17558 343too may suppress real errors in your runtime code. You are encouraged
89853d76 344wherever possible to apply the aforementioned approaches with explicit
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345absolute/relative paths, or to relocate your needed files into a
346subdirectory and insert that subdirectory into C<@INC> instead.
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347
348If your runtime code has problems under the dotless C<@INC>, then the comments
95b17558 349above on how to fix for script authors will mostly apply here too. Bear in
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350mind though that it is considered bad form for a module to globally add dot to
351C<@INC>, since it introduces both a security risk and hides issues of
352accidentally requiring dot in C<@INC>, as explained above.
353
354=back
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355
356=head2 "Escaped" colons and relative paths in PATH
357
358On Unix systems, Perl treats any relative paths in the PATH environment
359variable as tainted when starting a new process. Previously, it was
360allowing a backslash to escape a colon (unlike the OS), consequently
361allowing relative paths to be considered safe if the PATH was set to
362something like C</\:.>. The check has been fixed to treat C<.> as tainted
363in that example.
364
365=head2 C<-Di> switch is now required for PerlIO debugging output
366
367Previously PerlIO debugging output would be sent to the file specified
368by the C<PERLIO_DEBUG> environment variable if perl wasn't running
369setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
370
371If perl performed output at a point where it hadn't yet parsed its
372switches this could result in perl creating or overwriting the file
373named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
374
375Perl now requires the C<-Di> switch to produce PerlIO debugging
376output. By default this is written to C<stderr>, but can optionally
377be redirected to a file by setting the C<PERLIO_DEBUG> environment
378variable.
a049258c 379
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380If perl is running setuid or the C<-T> switch has supplied
381C<PERLIO_DEBUG> is ignored and the debugging output is sent to
382C<stderr> as for any other C<-D> switch.
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383
384=head1 Incompatible Changes
385
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386=head2 Unescaped literal C<"{"> characters in regular expression
387patterns are no longer permissible
a049258c 388
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389You have to now say something like C<"\{"> or C<"[{]"> to specify to
390match a LEFT CURLY BRACKET; otherwise it is a fatal pattern compilation
391error. This change will allow future extensions to the language.
392
393These have been deprecated since v5.16, with a deprecation message
394raised for some uses starting in v5.22. Unfortunately, the code added
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395to raise the message was buggy, and failed to warn in some cases where
396it should have. Therefore, enforcement of this ban for these cases is
397deferred until Perl 5.30, but the code has been fixed to raise a
398default-on deprecation message for them in the meantime.
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399
400Some uses of literal C<"{"> occur in contexts where we do not foresee
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401the meaning ever being anything but the literal, such as the very first
402character in the pattern, or after a C<"|"> meaning alternation. Thus
403
404 qr/{fee|{fie/
405
406matches either of the strings C<{fee> or C<{fie>. To avoid forcing
407unnecessary code changes, these uses do not need to be escaped, and no
408warning is raised about them, and there are no current plans to change this.
409
410But it is always correct to escape C<"{">, and the simple rule to
411remember is to always do so.
a049258c 412
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413=head2 C<scalar(%hash)> return signature changed
414
415The value returned for C<scalar(%hash)> will no longer show information about
416the buckets allocated in the hash. It will simply return the count of used
417keys. It is thus equivalent to C<0+keys(%hash)>.
418
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419A form of backwards compatibility is provided via
420L<C<Hash::Util::bucket_ratio()>|Hash::Util/bucket_ratio> which provides
421the same behavior as
422C<scalar(%hash)> provided in Perl 5.24 and earlier.
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423
424=head2 C<keys> returned from an lvalue subroutine
425
426C<keys> returned from an lvalue subroutine can no longer be assigned
427to in list context.
428
429 sub foo : lvalue { keys(%INC) }
430 (foo) = 3; # death
431 sub bar : lvalue { keys(@_) }
432 (bar) = 3; # also an error
433
434This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
435C<(keys @_) = ...>, which are also errors. [perl #128187]
a049258c 436
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437=head2 C<${^ENCODING}> has been removed
438
439Consequently, the L<encoding> pragma's default mode is no longer supported. If
440you still need to write your source code in encodings other than UTF-8, use a
441source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
442option.
443
444=head2 POSIX::tmpnam() has been removed
445
446The fundamentally unsafe C<tmpnam()> interface was deprecated in
53799a91 447Perl 5.22 and has now been removed. In its place you can use,
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448for example, the L<File::Temp> interfaces.
449
450=head2 require ::Foo::Bar is now illegal.
451
95b17558 452Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
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453bareword require which starts with a double colon dies instead.
454
455=head2 Literal control character variable names are no longer permissible
456
457A variable name may no longer contain a literal control character under
458any circumstances. These previously were allowed in single-character
459names on ASCII platforms, but have been deprecated there since Perl
4605.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
461control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
462source code.
463
464=head2 C<NBSP> is no longer permissible in C<\N{...}>
465
466The name of a character may no longer contain non-breaking spaces. It
53799a91 467has been deprecated to do so since Perl 5.22.
8d25d2f3 468
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469=head1 Deprecations
470
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471=head2 String delimiters that aren't stand-alone graphemes are now deprecated
472
473In order for Perl to eventually allow string delimiters to be Unicode
474grapheme clusters (which look like a single character, but may be
0f275d26 475a sequence of several ones), we have to stop allowing a single character
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476delimiter that isn't a grapheme by itself. These are unlikely to exist
477in actual code, as they would typically display as attached to the
478character in front of them.
479
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480=head1 Removed Deprecations
481
482The C<\cI<X>> construct is intended to be a way to specify non-printable
483characters. Previously it was deprecated to use it for a printable one,
484which is better written as simply itself, perhaps preceded by a
485backslash for non-word characters. Now this raises a warning, but not a
486deprecation. See
487L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>.
488
2c8edc25 489=head1 Performance Enhancements
a049258c 490
2c8edc25 491=over 4
a049258c 492
2c8edc25 493=item *
a049258c 494
fce64130 495A hash in boolean context is now sometimes faster, I<e.g.>
a049258c 496
2c8edc25 497 if (!%h) { ... }
a049258c 498
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499This was already special-cased, but some cases were missed (such as
500C<grep %$_, @AoH>, and even the ones which weren't have been improved.
a049258c 501
2c8edc25 502=item * New Faster Hash Function on 64 bit builds
a049258c 503
95b17558 504We use a different hash function for short and long keys. This should
2c8edc25 505improve performance and security, especially for long keys.
a049258c 506
2c8edc25 507=item * readline is faster
a049258c 508
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509Reading from a file line-by-line with C<readline()> or C<< E<lt>E<gt> >> should
510now typically be faster due to a better implementation of the code that
511searches for the next newline character.
512
513=item *
a049258c 514
2c8edc25 515Reduce cost of SvVALID().
a049258c 516
2c8edc25 517=item *
ad5c8857 518
2c8edc25 519C<$ref1 = $ref2> has been optimized.
5e50eae4 520
4b99a68c 521=item *
f4b40f11 522
fce64130 523Array and hash assignment are now faster, I<e.g.>
ec34c8a4 524
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525 (..., @a) = (...);
526 (..., %h) = (...);
f4b40f11 527
2c8edc25 528especially when the RHS is empty.
ec34c8a4 529
2c8edc25 530=item *
a049258c 531
2c8edc25 532Reduce the number of odd special cases for the C<SvSCREAM> flag.
e770df11 533
2c8edc25 534=item *
a049258c 535
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536Avoid sv_catpvn() in do_vop() when unneeded.
537
538=item *
539
540Enhancements in Regex concat COW implementation.
541
542=item *
543
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544Better optimise array and hash assignment: where an array or hash appears
545in the LHS of a list assignment, such as C<(..., @a) = (...);>, it's
546likely to be considerably faster, especially if it involves emptying the
547array/hash. For example this code runs about 1/3 faster compared to
5485.24.0:
d053832c
AB
549
550 my @a;
8928e7db 551 for my $i (1..10_000_000) {
d053832c
AB
552 @a = (1,2,3);
553 @a = ();
554 }
555
2c8edc25
S
556
557=item *
558
559Converting a single-digit string to a number is now substantially faster.
560
561=item *
562
563The internal op implementing the C<split> builtin has been simplified and
95b17558
KW
564sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
565to do its work. Secondly, code of the form C<my @x = split(...)> is now
2c8edc25
S
566optimised in the same way as C<@x = split(...)>, and is therefore a few
567percent faster.
568
569=item *
570
571The rather slow implementation for the experimental subroutine signatures
572feature has been made much faster; it is now comparable in speed with the
573old-style C<my ($a, $b, @c) = @_>.
7ca0bfc4 574
fbe3f407
S
575=item *
576
2c8edc25 577Bareword constant strings are now permitted to take part in constant
95b17558 578folding. They were originally exempted from constant folding in August 1999,
2c8edc25 579during the development of Perl 5.6, to ensure that C<use strict "subs">
95b17558 580would still apply to bareword constants. That has now been accomplished a
2c8edc25
S
581different way, so barewords, like other constants, now gain the performance
582benefits of constant folding.
583
584This also means that void-context warnings on constant expressions of
585barewords now report the folded constant operand, rather than the operation;
586this matches the behaviour for non-bareword constants.
a049258c
S
587
588=back
589
2c8edc25
S
590=head1 Modules and Pragmata
591
a049258c
S
592=head2 Updated Modules and Pragmata
593
594=over 4
fbe3f407 595
759020c9 596=item *
7ca0bfc4 597
0cc8c746
S
598L<Archive::Tar> has been upgraded from version 2.04 to 2.24.
599
600=item *
601
602L<arybase> has been upgraded from version 0.11 to 0.12.
603
604=item *
605
606L<attributes> has been upgraded from version 0.27 to 0.29.
a049258c 607
2c8edc25 608The deprecation message for the C<:unique> and C<:locked> attributes
0f275d26 609now mention that they will disappear in Perl 5.28.
a049258c 610
2c8edc25 611=item *
a049258c 612
0cc8c746
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613L<B> has been upgraded from version 1.62 to 1.68.
614
615=item *
616
617L<B::Concise> has been upgraded from version 0.996 to 0.999.
2c8edc25
S
618
619Its output is now more descriptive for C<op_private> flags.
d5c7a4fc 620
759020c9
S
621=item *
622
0cc8c746
S
623L<B::Debug> has been upgraded from version 1.23 to 1.24.
624
625=item *
626
627L<B::Deparse> has been upgraded from version 1.37 to 1.40.
628
629=item *
630
2c8edc25 631L<B::Xref> has been upgraded from version 1.05 to 1.06.
a049258c 632
2c8edc25 633It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 634
2c8edc25 635=item *
a049258c 636
0cc8c746
S
637L<base> has been upgraded from version 2.23 to 2.25.
638
639=item *
640
641L<bignum> has been upgraded from version 0.42 to 0.47.
642
643=item *
644
645L<Carp> has been upgraded from version 1.40 to 1.42.
646
647=item *
648
649L<charnames> has been upgraded from version 1.43 to 1.44.
650
651=item *
652
653L<Compress::Raw::Bzip2> has been upgraded from version 2.069 to 2.074.
654
655=item *
656
657L<Compress::Raw::Zlib> has been upgraded from version 2.069 to 2.074.
658
659=item *
660
661L<Config::Perl::V> has been upgraded from version 0.25 to 0.28.
662
663=item *
664
665L<CPAN> has been upgraded from version 2.11 to 2.18.
666
667=item *
668
669L<CPAN::Meta> has been upgraded from version 2.150005 to 2.150010.
670
671=item *
672
673L<Data::Dumper> has been upgraded from version 2.160 to 2.167.
a049258c 674
2c8edc25 675The XS implementation now supports Deparse.
a049258c 676
2c8edc25 677This fixes a stack management bug. [perl #130487].
a049258c 678
2c8edc25 679=item *
a049258c 680
0cc8c746
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681L<DB_File> has been upgraded from version 1.835 to 1.840.
682
683=item *
684
685L<Devel::Peek> has been upgraded from version 1.23 to 1.26.
686
687=item *
688
689L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
690
691=item *
692
2c8edc25 693L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
a049258c 694
2c8edc25 695It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 696
2c8edc25 697=item *
a049258c 698
0cc8c746 699L<diagnostics> has been upgraded from version 1.34 to 1.36.
a049258c 700
2c8edc25 701It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
7ca0bfc4 702
ad5c8857 703=item *
7ca0bfc4 704
0cc8c746
S
705L<Digest> has been upgraded from version 1.17 to 1.17_01.
706
707=item *
708
709L<Digest::MD5> has been upgraded from version 2.54 to 2.55.
710
711=item *
712
713L<Digest::SHA> has been upgraded from version 5.95 to 5.96.
714
715=item *
716
717L<DynaLoader> has been upgraded from version 1.38 to 1.42.
718
719=item *
720
721L<Encode> has been upgraded from version 2.80 to 2.88.
722
723=item *
724
725L<encoding> has been upgraded from version 2.17 to 2.19.
8f7edc68 726
ee8180b8 727This module's default mode is no longer supported. It now
2c8edc25 728dies when imported, unless the C<Filter> option is being used.
d5c7a4fc 729
2c8edc25 730=item *
d5c7a4fc 731
2c8edc25 732L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
a049258c 733
ee8180b8 734This module is no longer supported. It emits a warning to
2c8edc25 735that effect and then does nothing.
a049258c 736
2c8edc25 737=item *
d5c7a4fc 738
0cc8c746 739L<Errno> has been upgraded from version 1.25 to 1.28.
a049258c 740
2c8edc25 741Document that using C<%!> loads Errno for you.
d5c7a4fc 742
2c8edc25 743It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
3abe9611 744
c714fb1f 745=item *
3ce6a296 746
2c8edc25 747L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
a049258c 748
2c8edc25 749It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 750
2c8edc25 751=item *
a049258c 752
0cc8c746
S
753L<ExtUtils::MakeMaker> has been upgraded from version 7.10_01 to 7.24.
754
755=item *
756
757L<ExtUtils::Miniperl> has been upgraded from version 1.05 to 1.06.
758
759=item *
760
761L<ExtUtils::ParseXS> has been upgraded from version 3.31 to 3.34.
762
763=item *
764
765L<ExtUtils::Typemaps> has been upgraded from version 3.31 to 3.34.
766
767=item *
768
769L<feature> has been upgraded from version 1.42 to 1.47.
2c8edc25
S
770
771Fixes the Unicode Bug in the range operator.
a049258c
S
772
773=item *
5c92a635 774
0cc8c746
S
775L<File::Copy> has been upgraded from version 2.31 to 2.32.
776
777=item *
778
779L<File::Fetch> has been upgraded from version 0.48 to 0.52.
780
781=item *
782
783L<File::Glob> has been upgraded from version 1.26 to 1.28.
d5c7a4fc 784
2c8edc25 785Issue a deprecation message for C<File::Glob::glob()>.
d5c7a4fc 786
2c8edc25 787=item *
d5c7a4fc 788
0cc8c746
S
789L<File::Spec> has been upgraded from version 3.63 to 3.67.
790
791=item *
792
793L<FileHandle> has been upgraded from version 2.02 to 2.03.
794
795=item *
796
2c8edc25 797L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
a049258c 798
2c8edc25
S
799It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
800end-of-file. [perl #107726]
64afbd29
DM
801
802=item *
803
0cc8c746
S
804L<Getopt::Long> has been upgraded from version 2.48 to 2.49.
805
806=item *
807
808L<Getopt::Std> has been upgraded from version 1.11 to 1.12.
809
810=item *
811
812L<Hash::Util> has been upgraded from version 0.19 to 0.22.
813
814=item *
815
816L<HTTP::Tiny> has been upgraded from version 0.056 to 0.070.
a049258c 817
2c8edc25 818Internal 599-series errors now include the redirect history.
a049258c 819
2c8edc25 820=item *
a049258c 821
0cc8c746 822L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
a049258c 823
2c8edc25 824It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 825
2c8edc25 826=item *
a049258c 827
0cc8c746
S
828L<IO> has been upgraded from version 1.36 to 1.38.
829
830=item *
831
601d9a87 832IO-Compress has been upgraded from version 2.069 to 2.074.
0cc8c746
S
833
834=item *
835
836L<IO::Socket::IP> has been upgraded from version 0.37 to 0.38.
837
838=item *
839
840L<IPC::Cmd> has been upgraded from version 0.92 to 0.96.
841
842=item *
843
844L<IPC::SysV> has been upgraded from version 2.06_01 to 2.07.
845
846=item *
847
848L<JSON::PP> has been upgraded from version 2.27300 to 2.27400_02.
849
850=item *
851
2c8edc25
S
852L<lib> has been upgraded from version 0.63 to 0.64.
853
854It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
faab9793 855
c714fb1f 856=item *
ad5c8857 857
0cc8c746
S
858L<List::Util> has been upgraded from version 1.42_02 to 1.46_02.
859
860=item *
861
862L<Locale::Codes> has been upgraded from version 3.37 to 3.42.
863
864=item *
865
866L<Locale::Maketext> has been upgraded from version 1.26 to 1.28.
867
868=item *
869
870L<Locale::Maketext::Simple> has been upgraded from version 0.21 to 0.21_01.
871
872=item *
873
874L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
ad5c8857 875
2c8edc25 876There have also been some core customizations.
ad5c8857 877
2c8edc25 878=item *
2e0dcc12 879
0cc8c746
S
880L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
881
882=item *
883
884L<Math::BigRat> has been upgraded from version 0.260802 to 0.2611.
885
886=item *
887
888L<Math::Complex> has been upgraded from version 1.59 to 1.5901.
889
890=item *
891
892L<Memoize> has been upgraded from version 1.03 to 1.03_01.
893
894=item *
895
896L<Module::CoreList> has been upgraded from version 5.20170420 to 5.20170520.
897
898=item *
899
900L<Module::Load::Conditional> has been upgraded from version 0.64 to 0.68.
901
902=item *
903
904L<Module::Metadata> has been upgraded from version 1.000031 to 1.000033.
905
906=item *
907
908L<mro> has been upgraded from version 1.18 to 1.20.
909
910=item *
911
912L<Net::Ping> has been upgraded from version 2.43 to 2.55.
d5c7a4fc 913
2c8edc25
S
914IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
915other enhancements.
d5c7a4fc 916
2c8edc25
S
917Remove sudo from 500_ping_icmp.t.
918
919Avoid stderr noise in tests
920
0f275d26 921Check for echo in new L<Net::Ping> tests.
d5c7a4fc 922
a049258c 923=item *
d5c7a4fc 924
0cc8c746
S
925L<NEXT> has been upgraded from version 0.65 to 0.67.
926
927=item *
928
929L<Opcode> has been upgraded from version 1.34 to 1.39.
930
931=item *
932
933L<open> has been upgraded from version 1.10 to 1.11.
934
935=item *
936
2c8edc25 937L<OS2::Process> has been upgraded from version 1.11 to 1.12.
a049258c 938
2c8edc25 939It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c 940
2c8edc25 941=item *
a049258c 942
2c8edc25 943L<overload> has been upgraded from version 1.26 to 1.28.
a049258c 944
2c8edc25 945Its compilation speed has been improved slightly.
a049258c 946
2c8edc25
S
947=item *
948
0cc8c746
S
949L<parent> has been upgraded from version 0.234 to 0.236.
950
951=item *
952
2c8edc25
S
953L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
954
955Ignore F</dev/tty> on non-Unix systems. [perl #113960]
956
957=item *
958
0cc8c746
S
959L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
960
961=item *
962
963L<perlfaq> has been upgraded from version 5.021010 to 5.021011.
964
965=item *
966
967L<PerlIO> has been upgraded from version 1.09 to 1.10.
968
969=item *
970
971L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
972
973=item *
974
975L<PerlIO::scalar> has been upgraded from version 0.24 to 0.26.
976
977=item *
978
979L<Pod::Checker> has been upgraded from version 1.60 to 1.73.
980
981=item *
982
983L<Pod::Functions> has been upgraded from version 1.10 to 1.11.
984
985=item *
986
987L<Pod::Html> has been upgraded from version 1.22 to 1.2202.
988
989=item *
990
991L<Pod::Perldoc> has been upgraded from version 3.25_02 to 3.28.
992
993=item *
994
995L<Pod::Simple> has been upgraded from version 3.32 to 3.35.
996
997=item *
998
999L<Pod::Usage> has been upgraded from version 1.68 to 1.69.
1000
1001=item *
1002
95b17558 1003L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
2c8edc25
S
1004defects in making its symbols exportable. [perl #127821]
1005The C<POSIX::tmpnam()> interface has been removed,
1006see L</"POSIX::tmpnam() has been removed">.
1007Trying to import POSIX subs that have no real implementations
1008(like C<POSIX::atend()>) now fails at import time, instead of
1009waiting until runtime.
1010
1011=item *
1012
0cc8c746 1013L<re> has been upgraded from version 0.32 to 0.34
2c8edc25
S
1014
1015This adds support for the new L<C<E<47>xx>|perlre/E<sol>x and E<sol>xx>
1016regular expression pattern modifier, and a change to the L<S<C<use re
1017'strict'>>|re/'strict' mode> experimental feature. When S<C<re
1018'strict'>> is enabled, a warning now will be generated for all
1019unescaped uses of the two characters C<}> and C<]> in regular
1020expression patterns (outside bracketed character classes) that are taken
1021literally. This brings them more in line with the C<)> character which
1022is always a metacharacter unless escaped. Being a metacharacter only
1023sometimes, depending on action at a distance, can lead to silently
1024having the pattern mean something quite different than was intended,
1025which the S<C<re 'strict'>> mode is intended to minimize.
1026
1027=item *
1028
0cc8c746
S
1029L<Safe> has been upgraded from version 2.39 to 2.40.
1030
1031=item *
1032
1033L<Scalar::Util> has been upgraded from version 1.42_02 to 1.46_02.
1034
1035=item *
1036
1037L<Storable> has been upgraded from version 2.56 to 2.62.
2c8edc25
S
1038
1039Fixes [perl #130098].
1040
1041=item *
1042
0cc8c746
S
1043L<Symbol> has been upgraded from version 1.07 to 1.08.
1044
1045=item *
1046
1047L<Sys::Syslog> has been upgraded from version 0.33 to 0.35.
1048
1049=item *
1050
1051L<Term::ANSIColor> has been upgraded from version 4.04 to 4.06.
1052
1053=item *
1054
2c8edc25
S
1055L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
1056
1057It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1058
1059=item *
1060
0cc8c746 1061L<Test> has been upgraded from version 1.28 to 1.30.
2c8edc25
S
1062
1063It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1064
1065=item *
1066
0cc8c746
S
1067L<Test::Harness> has been upgraded from version 3.36 to 3.38.
1068
1069=item *
1070
1071L<Test::Simple> has been upgraded from version 1.001014 to 1.302073.
1072
1073=item *
1074
1075L<Thread::Queue> has been upgraded from version 3.09 to 3.12.
1076
1077=item *
1078
2c8edc25
S
1079L<Thread::Semaphore> has been upgraded from 2.12 to 2.13.
1080
1081Added the C<down_timed> method.
1082
1083=item *
1084
0cc8c746 1085L<threads> has been upgraded from version 2.07 to 2.15.
2c8edc25
S
1086
1087Compatibility with 5.8 has been restored.
1088
1089Fixes [perl #130469].
1090
1091=item *
1092
0cc8c746 1093L<threads::shared> has been upgraded from version 1.51 to 1.56.
2c8edc25
S
1094
1095This fixes [cpan #119529], [perl #130457]
1096
1097=item *
1098
0cc8c746
S
1099L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
1100
1101=item *
1102
1103L<Time::HiRes> has been upgraded from version 1.9733 to 1.9741.
2c8edc25
S
1104
1105It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
11063.9).
1107
1108Now uses C<clockid_t>.
1109
1110=item *
1111
0cc8c746
S
1112L<Time::Local> has been upgraded from version 1.2300 to 1.25.
1113
1114=item *
1115
1116L<Unicode::Collate> has been upgraded from version 1.14 to 1.19.
1117
1118=item *
1119
1120L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
2c8edc25
S
1121
1122It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
1123
1124=item *
1125
0cc8c746
S
1126L<version> has been upgraded from version 0.9916 to 0.9917.
1127
1128=item *
1129
1130L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
2c8edc25
S
1131
1132It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1133
1134=item *
1135
0cc8c746
S
1136L<warnings> has been upgraded from version 1.36 to 1.37.
1137
1138=item *
1139
1140L<XS::Typemap> has been upgraded from version 0.14 to 0.15.
1141
1142=item *
1143
1144L<XSLoader> has been upgraded from version 0.21 to 0.27.
2c8edc25
S
1145
1146Fixed a security hole in which binary files could be loaded from a path
1147outside of L<C<@INC>|perlvar/@INC>.
1148
1149It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
a049258c
S
1150
1151=back
1152
2c8edc25
S
1153=head1 Documentation
1154
1155=head2 New Documentation
a049258c 1156
2c8edc25 1157=head3 L<perldeprecation>
a049258c 1158
2c8edc25 1159This file documents all upcoming deprecations, and some of the deprecations
95b17558 1160which already have been removed. The purpose of this documentation is
2c8edc25
S
1161two-fold: document what will disappear, and by which version, and serve
1162as a guide for people dealing with code which has features that no longer
1163work after an upgrade of their perl.
a049258c 1164
2c8edc25 1165=head2 Changes to Existing Documentation
a049258c 1166
b10de59c
KW
1167We have attempted to update the documentation to reflect the changes
1168listed in this document. If you find any we have missed, send email to
1169L<mailto:perlbug@perl.org>.
a049258c 1170
b10de59c
KW
1171Additionally all references to Usenet have been removed, and the
1172following selected changes have been made:
2c8edc25 1173
b10de59c 1174=head3 L<perlfunc>
a049258c 1175
b10de59c 1176=over 4
a049258c 1177
2c8edc25
S
1178=item *
1179
b10de59c
KW
1180Removed obsolete text about L<C<defined()>|perlfunc/defined>
1181on aggregates that should have been deleted earlier, when the feature
1182was removed.
2c8edc25
S
1183
1184=item *
1185
b10de59c
KW
1186Corrected documentation of L<C<eval()>|perlfunc/eval>,
1187and L<C<evalbytes()>|perlfunc/evalbytes>.
a049258c 1188
2c8edc25 1189=item *
a049258c 1190
b10de59c
KW
1191Clarified documentation of L<C<seek()>|perlfunc/seek>,
1192L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>
1193regarding that positions are in bytes vs. characters.
1194L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
2c8edc25
S
1195
1196=item *
1197
b10de59c
KW
1198Clarified documentation of L<C<sort()>|perlfunc/sort LIST> concerning
1199the variables C<$a> and C<$b>.
2c8edc25
S
1200
1201=item *
a049258c 1202
b10de59c
KW
1203In L<C<split()>|perlfunc/split> added a caution about its use in Perls
1204before 5.11, and noted that certain pattern modifiers are legal in it.
a049258c 1205
2c8edc25 1206=item *
a049258c 1207
b10de59c
KW
1208Removed obsolete documentation of L<C<study()>|perlfunc/study>, noting
1209that it is now a no-op.
2c8edc25
S
1210
1211=item *
1212
b10de59c
KW
1213Noted that L<C<vec()>|perlfunc/vec> doesn't work well when the string
1214contains characters whose code points are above 255.
a049258c 1215
2c8edc25 1216=back
a049258c 1217
b10de59c 1218=head3 L<perlguts>
a049258c
S
1219
1220=over 4
1221
1222=item *
1223
b10de59c
KW
1224Added advice on
1225L<formatted printing of operands of C<Size_t> and C<SSize_t>|perlguts/Formatted Printing of Size_t and SSize_t>
a049258c
S
1226
1227=back
1228
b10de59c 1229=head3 L<perlhack>
2c8edc25
S
1230
1231=over 4
1232
1233=item *
1234
b10de59c
KW
1235Clariy indentation rules, and note that we are migrating away from using
1236tabs to indent, replacing them with sequences of SPACE characters.
2c8edc25
S
1237
1238=back
a049258c 1239
b10de59c 1240=head3 L<perlhacktips>
a049258c
S
1241
1242=over 4
1243
1244=item *
1245
b10de59c 1246Give another reason to use C<cBOOL> to cast an expression to boolean.
2c8edc25
S
1247
1248=item *
1249
b10de59c
KW
1250Note that there are macros C<TRUE> and C<FALSE> available to express
1251boolean values.
a049258c 1252
2c8edc25 1253=back
a049258c 1254
2c8edc25 1255=head3 L<perlinterp>
a049258c
S
1256
1257=over 4
1258
1259=item *
1260
2c8edc25
S
1261L<perlinterp> has been expanded to give a more detailed example of how to
1262hunt around in the parser for how a given operator is handled.
a049258c
S
1263
1264=back
1265
2c8edc25 1266=head3 L<perllocale>
a049258c
S
1267
1268=over 4
1269
b10de59c
KW
1270Some locales aren't compatible with Perl. Note that these can cause
1271core dumps.
a049258c
S
1272
1273=back
1274
2c8edc25
S
1275=head3 L<perlmodinstall>
1276
1277=over 4
1278
1279=item *
1280
b10de59c 1281Various clarifications have been added.
2c8edc25
S
1282
1283=back
1284
1285=head3 L<perlmodlib>
1286
1287=over 4
1288
1289=item *
1290
b10de59c 1291Updated the site mirror list.
2c8edc25
S
1292
1293=back
1294
1295=head3 L<perlobj>
1296
1297=over 4
1298
1299=item *
1300
1301Added a section on calling methods using their fully qualified names.
1302
1303=item *
1304
1305Do not discourage manual @ISA.
1306
1307=back
1308
1309=head3 L<perlootut>
1310
1311=over 4
1312
1313=item *
1314
2c8edc25
S
1315Mention C<Moo> more.
1316
1317=back
1318
1319=head3 L<perlop>
1320
1321=over 4
1322
1323=item *
1324
0f275d26 1325Clarify behavior of single quote regexps.
2c8edc25
S
1326
1327=back
1328
1329=head3 L<perlre>
1330
1331=over 4
1332
1333=item *
1334
1c34b59a
KW
1335The first part was extensively rewritten to incorporate various basic
1336points, that in earlier versions were mentioned in sort of an appendix
1337on Version 8 regular expressions.
1338
b10de59c
KW
1339Note that it is common to have the C</x> modifier and forget that this
1340means that C<"#"> has to be escaped.
2c8edc25
S
1341
1342=back
1343
b10de59c 1344=head3 L<perlretut>
2c8edc25
S
1345
1346=over 4
1347
1348=item *
1349
b10de59c 1350Add introductory material
2c8edc25
S
1351
1352=item *
1353
b10de59c
KW
1354Note that a metacharacter occurring in a context where it can't mean
1355that, silently loses its meta-ness and matches literally.
1356L<C<use re 'strict'>|re/'strict' mode> can catch some of these.
2c8edc25
S
1357
1358=back
1359
1360=head3 L<perlunicode>
1361
1362=over 4
1363
1364=item *
1365
b10de59c 1366Corrected the text about Unicode BYTE ORDER MARK handling.
2c8edc25
S
1367
1368=item *
1369
1370Updated the text to correspond with changes in Unicode UTS#18, concerning
1371regular expressions, and Perl compatibility with what it says.
1372
1373=back
1374
1375=head3 L<perlvar>
1376
1377=over 4
1378
1379=item *
1380
95b17558 1381Document C<@ISA>. Was documented other places, not not in L<perlvar>.
2c8edc25
S
1382
1383=back
1384
1385=head1 Diagnostics
1386
1387=head2 New Diagnostics
1388
1389=head3 New Errors
1390
1391=over 4
1392
1393=item *
1394
1395Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1396a warning recommending to fix the C<do> statement:
1397
1398L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
1399
1400=item *
1401
1402Using the empty pattern (which re-executes the last successfully-matched
1403pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
95b17558 1404always previously yielded a segfault. It now produces an error:
4f73c567 1405L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
2c8edc25
S
1406
1407=item *
1408
1409L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
1410
1411(F) To declare references to variables, as in C<my \%x>, you must first enable
1412the feature:
1413
1414 no warnings "experimental::declared_refs";
1415 use feature "declared_refs";
1416
1417=item *
1418
1419L<Version control conflict marker|perldiag/"Version control conflict marker">
1420
e6abae1c 1421(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
95b17558 1422C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
2c8edc25
S
1423version control system to mark conflicts after a failed merge operation.
1424
1425=item *
1426
1427L<%s: command not found|perldiag/"%s: command not found">
1428
1429(A) You've accidentally run your script through B<bash> or another shell
1430instead of Perl. Check the #! line, or manually feed your script into
1431Perl yourself. The #! line at the top of your file could look like:
1432
1433 #!/usr/bin/perl
1434
1435=item *
1436
1437L<%s: command not found: %s|perldiag/"%s: command not found: %s">
1438
1439(A) You've accidentally run your script through B<zsh> or another shell
1440instead of Perl. Check the #! line, or manually feed your script into
1441Perl yourself. The #! line at the top of your file could look like:
1442
1443 #!/usr/bin/perl
1444
1445=item *
1446
d8362e1b 1447L<Unescaped left brace in regex is illegal here|perldiag/Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in m/%s/>
2c8edc25 1448
d8362e1b
KW
1449Unescaped left braces are now illegal in some contexts in regular expression
1450patterns. In other contexts, they are still just deprecated; they will
1451be illegal in Perl 5.30.
2c8edc25
S
1452
1453=item *
1454
1455L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
1456
1457=item *
1458
1459L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
1460
1461=item *
1462
1463L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
1464
1465=item *
1466
1467L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
1468
1469=back
1470
1471=head3 New Warnings
1472
1473=over 4
1474
1475=item *
1476
4f73c567 1477L<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
1478
1479See L</Deprecations>
1480
1481=item *
1482
1483L<Declaring references is experimental|perldiag/"Declaring references is experimental">
1484
1485(S experimental::declared_refs) This warning is emitted if you use a reference
1486constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
1487C<local()>. Simply suppress the warning if you want to use the feature, but
1488know that in doing so you are taking the risk of using an experimental feature
1489which may change or be removed in a future Perl version:
1490
1491 no warnings "experimental::declared_refs";
1492 use feature "declared_refs";
1493 $fooref = my \$foo;
1494
1495=item *
1496
4f73c567 1497L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
2c8edc25 1498
0f275d26 1499The special variable C<${^ENCODING}>, formerly used to implement
53799a91 1500the C<encoding> pragma, is no longer supported as of Perl 5.26.
2c8edc25 1501
89853d76
DH
1502=item *
1503
1504Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
1505a warning recommending to fix the C<do> statement:
1506
fc902710 1507L<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 1508
2c8edc25
S
1509=back
1510
1511=head2 Changes to Existing Diagnostics
1512
1513=over 4
1514
1515=item *
1516
1517When a C<require> fails, we now do not provide C<@INC> when the C<require>
1518is for a file instead of a module.
1519
1520=item *
1521
1522When C<@INC> is not scanned for a C<require> call, we no longer display
1523C<@INC> to avoid confusion.
1524
1525=item *
1526
1527Attribute "locked" is deprecated, and will disappear in Perl 5.28
1528
1529=item *
1530
1531Attribute "unique" is deprecated, and will disappear in Perl 5.28
1532
1533=item *
1534
1535Constants from lexical variables potentially modified elsewhere are
1536deprecated. This will not be allowed in Perl 5.32
1537
1538=item *
1539
1540Deprecated use of my() in false conditional. This will be a fatal error
1541in Perl 5.30
1542
1543=item *
1544
1545dump() better written as CORE::dump(). dump() will no longer be available
1546in Perl 5.30
1547
1548=item *
1549
1550${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
1551
1552=item *
1553
1554File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
1555instead.
1556
1557=item *
1558
1559%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
1560
1561=item *
1562
1563$* is no longer supported. Its use will be fatal in Perl 5.30
1564
1565=item *
1566
1567$* is no longer supported. Its use will be fatal in Perl 5.30
1568
1569=item *
1570
1571Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
1572
1573=item *
1574
1575Opening filehandle %s also as a directory. This will be a fatal
1576error in Perl 5.28
1577
1578=item *
1579
1580Setting $/ to a reference to %s as a form of slurp is deprecated,
1581treating as undef. This will be fatal in Perl 5.28
1582
1583=item *
1584
1585Unescaped left brace in regex is deprecated here (and will be fatal
1586in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
1587
1588=item *
1589
1590Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
1591
1592=item *
1593
1594Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
1595
1596=item *
1597
1598Use of code point 0x%s is deprecated; the permissible max is 0x%s.
1599This will be fatal in Perl 5.28
1600
1601=item *
1602
1603Use of comma-less variable list is deprecated. Its use will be fatal
1604in Perl 5.28
1605
1606=item *
1607
1608Use of inherited AUTOLOAD for non-method %s() is deprecated. This
1609will be fatal in Perl 5.28
1610
1611=item *
1612
1613Use of strings with code points over 0xFF as arguments to %s operator
1614is deprecated. This will be a fatal error in Perl 5.28
1615
1616=item *
1617
1618Improve error for missing tie() package/method. This brings the error messages
1619in line with the ones used for normal method calls, despite not using
1620call_method().
1621
1622=item *
1623
1624Make the sysread()/syswrite/() etc :utf8 handle warnings default. These
1625warnings were under 'deprecated' previously.
1626
1627=item *
1628
1629'do' errors now refer to 'do' (not 'require').
1630
1631=item *
1632
1633Details as to the exact problem have been added to the diagnostics that
1634occur when malformed UTF-8 is encountered when trying to convert to a
1635code point.
1636
1637=item *
1638
1639Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
1640blames the variable for an uninitialized-value warning encountered by the
1641tied/magical code.
1642
1643=item *
1644
2c8edc25
S
1645Code like C<$x = $x . "a"> was incorrectly failing to yield a
1646L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
1647warning when C<$x> was a lexical variable with an undefined value. That has
1648now been fixed. [perl #127877]
1649
1650=item *
1651
1652When the error "Experimental push on scalar is now forbidden" is raised for
1653the hash functions C<keys>, C<each>, and C<values>, it is now followed by
1654the more helpful message, "Type of arg 1 to whatever must be hash or
1655array". [perl #127976]
1656
1657=item *
1658
1659C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
53799a91 1660argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
2c8edc25
S
1661been fixed.
1662
1663=item *
1664
1665C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
1666string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
1667bringing it into consistency with C<$$scalar>.
1668
1669=item *
1670
1671C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
1672do, but merely produce a syntax error. [perl #128171]
1673
1674=item *
1675
1676C<do> or C<require> with a reference or typeglob which, when stringified,
53799a91 1677contains a null character started crashing in Perl 5.20, but has now been
2c8edc25
S
1678fixed. [perl #128182]
1679
1680=back
1681
1682=head1 Utility Changes
1683
1684=head2 F<c2ph> and F<pstruct>
1685
1686=over 4
1687
1688=item *
1689
1690These old utilities have long since superceded by L<h2xs>, and are
1691now gone from the distribution.
1692
1693=back
1694
1695=head2 F<Porting/pod_lib.pl>
1696
1697=over 4
1698
1699=item *
1700
1701Removed spurious executable bit.
1702
1703=item *
1704
1705Account for possibility of DOS file endings.
1706
1707=back
1708
1709=head2 F<Porting/sync-with-cpan>
1710
1711=over 4
1712
1713=item *
1714
1715Many improvements
1716
1717=back
1718
1719=head2 F<perf/benchmarks>
1720
1721=over 4
1722
1723=item *
1724
1725Tidy file, rename some symbols.
1726
1727=back
1728
1729=head2 F<Porting/checkAUTHORS.pl>
1730
1731=over 4
1732
1733=item *
1734
0f275d26 1735Replace obscure character range with C<\w>.
2c8edc25
S
1736
1737=back
1738
1739=head2 F<t/porting/regen.t>
1740
1741=over 4
1742
1743=item *
1744
1745try to be more helpful when tests fail.
1746
1747=back
1748
1749=head2 F<utils/h2xs.PL>
1750
1751=over 4
1752
1753=item *
1754
1755Avoid infinite loop for enums.
1756
1757=back
1758
1759=head2 L<perlbug>
1760
1761=over 4
1762
1763=item *
1764
1765Long lines in the message body are now wrapped at 900 characters, to stay
1766well within the 1000-character limit imposed by SMTP mail transfer agents.
1767This is particularly likely to be important for the list of arguments to
1768C<Configure>, which can readily exceed the limit if, for example, it names
95b17558 1769several non-default installation paths. This change also adds the first unit
2c8edc25
S
1770tests for perlbug. [perl #128020]
1771
1772=back
1773
1774=head1 Configuration and Compilation
1775
1776=over 4
1777
1778=item *
1779
89853d76 1780C<-Ddefault_inc_excludes_dot> has been turned on by default.
2c8edc25
S
1781
1782=item *
1783
1784The C<dtrace> build process has further changes:
1785
1786=over
1787
1788=item *
1789
1790If the C<-xnolibs> is available, use that so a F<dtrace> perl can be
1791built within a FreeBSD jail.
1792
1793=item *
1794
1795On systems that build a dtrace object file (FreeBSD, Solaris and
1796SystemTap's dtrace emulation), copy the input objects to a separate
1797directory and process them there, and use those objects in the link,
1798since C<dtrace -G> also modifies these objects.
1799
1800=item *
1801
1802Add libelf to the build on FreeBSD 10.x, since dtrace adds references
1803to libelf symbols.
1804
1805=item *
1806
1807Generate a dummy dtrace_main.o if C<dtrace -G> fails to build it. A
1808default build on Solaris generates probes from the unused inline
1809functions, while they don't on FreeBSD, which causes C<dtrace -G> to
1810fail.
1811
1812=back
1813
1814[perl #130108]
1815
1816=item *
1817
1818You can now disable perl's use of the PERL_HASH_SEED and
1819PERL_PERTURB_KEYS environment variables by configuring perl with
1820C<-Accflags=NO_PERL_HASH_ENV>.
1821
1822=item *
1823
1824You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment
1825variable by configuring perl with
1826C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
1827
1828=item *
1829
1830Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
1831and C<Inf> to make builds more reproducible. [perl #130133]
1832
1833=item *
1834
1835Since 5.18 for testing purposes we have included support for
1836building perl with a variety of non-standard, and non-recommended
95b17558
KW
1837hash functions. Since we do not recommend the use of these functions
1838we have removed them and their corresponding build options. Specifically
2c8edc25
S
1839this includes the following build options:
1840
1841 PERL_HASH_FUNC_SDBM
1842 PERL_HASH_FUNC_DJB2
1843 PERL_HASH_FUNC_SUPERFAST
1844 PERL_HASH_FUNC_MURMUR3
1845 PERL_HASH_FUNC_ONE_AT_A_TIME
1846 PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
1847 PERL_HASH_FUNC_MURMUR_HASH_64A
1848 PERL_HASH_FUNC_MURMUR_HASH_64B
1849
1850=item *
1851
1852Remove "Warning: perl appears in your path"
1853
1854This install warning is more or less obsolete, since most platforms already
1855*will* have a /usr/bin/perl or similar provided by the OS.
1856
1857=item *
1858
1859Reduce verbosity of "make install.man"
1860
1861Previously, two progress messages were emitted for each manpage: one by
1862installman itself, and one by the function in install_lib.pl that it calls to
95b17558 1863actually install the file. Disabling the second of those in each case saves
2c8edc25
S
1864over 750 lines of unhelpful output.
1865
1866=item *
1867
1868Cleanup for clang -Weverything support. [perl 129961]
1869
1870=item *
1871
1872Configure: signbit scan was assuming too much, stop assuming negative 0.
1873
1874=item *
1875
1876Various compiler warnings have been silenced.
1877
1878=item *
1879
1880Several smaller changes have been made to remove impediments to compiling under
1881C++11.
1882
1883=item *
1884
1885Builds using C<USE_PAD_RESET> now work again; this configuration had
1886bit-rotted.
1887
1888=item *
1889
1890A probe for C<gai_strerror> was added to F<Configure> that checks if the
1891the gai_strerror() routine is available and can be used to
1892translate error codes returned by getaddrinfo() into human
1893readable strings.
1894
1895=item *
1896
1897F<Configure> now aborts if both "-Duselongdouble" and "-Dusequadmath" are
1898requested.
1899L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
1900
1901=item *
1902
1903Fixed a bug in which F<Configure> could append "-quadmath" to the archname even
1904if it was already present.
1905L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
1906
1907=item *
1908
1909Clang builds with "-DPERL_GLOBAL_STRUCT" or "-DPERL_GLOBAL_STRUCT_PRIVATE" have
1910been fixed (by disabling Thread Safety Analysis for these configurations).
1911
1912=item *
1913
1914F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
1915files require updates. This could cause dependencies, F<perlmain.c>
1916in particular, to be rebuilt unnecessarily. [perl #126710]
1917
1918=item *
1919
1920The output of C<perl -V> has been reformatted so that each configuration
1921and compile-time option is now listed one per line, to improve
1922readability.
1923
1924=item *
1925
1926C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
1927invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
1928This means you can supply your target platform C<config.sh>, generate
1929the headers and proceed to build your cross-target perl. [perl #127234]
1930
1931=item *
1932
1933Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
1934counts when the environment variable C<PERL_TRACE_OPS> to be set to a
1935non-zero integer. This allows C<make test> to pass on such a build.
1936
1937=item *
1938
1939When building with GCC 6 and link-time optimization (the C<-flto> option to
1940C<gcc>), C<Configure> was treating all probed symbols as present on the
95b17558 1941system, regardless of whether they actually exist. This has been fixed.
2c8edc25
S
1942[perl #128131]
1943
1944=item *
1945
1946The F<t/test.pl> library is used for internal testing of Perl itself, and
95b17558 1947also copied by several CPAN modules. Some of those modules must work on
2c8edc25 1948older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
95b17558 1949features. Compatibility with Perl 5.8 was inadvertently removed some time
2c8edc25
S
1950ago; it has now been restored. [perl #128052]
1951
1952=item *
1953
1954The build process no longer emits an extra blank line before building each
1955"simple" extension (those with only F<*.pm> and F<*.pod> files).
1956
1957=back
1958
1959=head1 Testing
1960
1961=over 4
1962
1963=item *
1964
1965F<XS-APItest/t/utf8.t>: Several small fixes and enhancements.
1966
1967=item *
1968
1969Tests for locales were erroneously using locales incompatible with Perl.
1970
1971=item *
1972
1973Some parts of the test suite that try to exhaustively test edge cases in the
1974regex implementation have been restricted to running for a maximum of five
95b17558 1975minutes. On slow systems they could otherwise take several hours, without
2c8edc25
S
1976significantly improving our understanding of the correctness of the code
1977under test.
1978
1979In addition, some of those test cases have been split into more files, to
1980allow them to be run in parallel on suitable systems.
1981
1982=item *
1983
1984A new internal facility allows analysing the time taken by the individual
1985tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
1986
1987=item *
1988
1989F<t/re/regexp_nonull.t> has been added to test that the regular expression
1990engine can handle scalars that do not have a null byte just past the end of
1991the string.
1992
1993=item *
1994
1995A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
1996"Declaring a reference to a variable".
1997
1998=item *
1999
2000A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
2001generated by bracketed character classes are as expected.
2002
2003=item *
2004
2005F<t/harness> now tries really hard not to run tests outside of the Perl
2006source tree. [perl #124050]
2007
2008=back
2009
2010=head1 Platform Support
2011
2012=head2 New Platforms
2013
2014=over 4
2015
2016=item NetBSD/VAX
2017
2018Perl now compiles under NetBSD on VAX machines. However, it's not
2019possible for that platform to implement floating-point infinities and
2020NaNs compatibly with most modern systems, which implement the IEEE-754
2021floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
2022literals, C<printf %a>) is not implemented, either.
2023The C<make test> passes 98% of tests.
2024
2025=over 4
2026
2027=item *
2028
2029Test fixes and minor updates.
2030
2031=item *
2032
2033Account for lack of C<inf>, C<nan>, and C<-0.0> support.
2034
2035=back
2036
2037=back
2038
2039=head2 Platform-Specific Notes
2040
2041=over 4
2042
2043=item Darwin
2044
2045don't treat -Dprefix=/usr as special, instead require an extra option
2046-Ddarwin_distribution to produce the same results.
2047
2048=item POSIX
2049
2050Finish removing POSIX deprecated functions.
2051
2052=item OS X
2053
29ce4d71 2054OS X El Capitan doesn't implement the clock_gettime() or clock_getres() APIs;
2c8edc25
S
2055emulate them as necessary.
2056
2057=item macOS
2058
2059Deprecated syscall(2) on macOS 10.12.
2060
2061=item EBCDIC
2062
2063Several tests have been updated to work (or be skipped) on EBCDIC platforms.
2064
2065=item HP-UX
2066
2067L<Net::Ping> UDP test is skipped on HP-UX.
2068
2069=item Hurd
2070
2071The hints for Hurd have been improved enabling malloc wrap and reporting the
2072GNU libc used (previously it was an empty string when reported).
2073
2074=item VAX
2075
29ce4d71 2076VAX floating point formats are now supported on NetBSD.
2c8edc25
S
2077
2078=item VMS
2079
2080=over 4
2081
2082=item *
2083
2084The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
95b17558 2085now a colon (C<:>) when running under a Unix shell. There is no change when
2c8edc25
S
2086running under DCL (it's still C<|>).
2087
2088=item *
2089
29ce4d71
CB
2090C<configure.com> now recognizes the VSI-branded C compiler and no longer
2091recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
209215 or more years).
2c8edc25
S
2093
2094=back
2095
2096=item Windows
2097
2098=over 4
2099
2100=item *
2101
2102Support for compiling perl on Windows using Microsoft Visual Studio 2015
2103(containing Visual C++ 14.0) has been added.
2104
2105This version of VC++ includes a completely rewritten C run-time library, some
2106of the changes in which mean that work done to resolve a socket close() bug in
2107perl #120091 and perl #118059 is not workable in its current state with this
2108version of VC++. Therefore, we have effectively reverted that bug fix for
2109VS2015 onwards on the basis that being able to build with VS2015 onwards is
2110more important than keeping the bug fix. We may revisit this in the future to
2111attempt to fix the bug again in a way that is compatible with VS2015.
2112
2113These changes do not affect compilation with GCC or with Visual Studio versions
fce64130 2114up to and including VS2013, I<i.e.>, the bug fix is retained (unchanged) for those
2c8edc25
S
2115compilers.
2116
2117Note that you may experience compatibility problems if you mix a perl built
2118with GCC or VS E<lt>= VS2013 with XS modules built with VS2015, or if you mix a
2119perl built with VS2015 with XS modules built with GCC or VS E<lt>= VS2013.
2120Some incompatibility may arise because of the bug fix that has been reverted
2121for VS2015 builds of perl, but there may well be incompatibility anyway because
fce64130 2122of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
2c8edc25
S
2123http://stackoverflow.com/questions/30412951).
2124
2125=back
2126
2127=item Win32
2128
2129=over 4
2130
2131=item *
2132
95b17558 2133Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
2c8edc25 2134depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
95b17558 2135the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
2c8edc25
S
2136
2137=item *
2138
2139fp definitions have been updated.
2140
2141=back
2142
2c8edc25
S
2143=item Linux
2144
2145Drop support for Linux a.out Linux has used ELF for over twenty years.
2146
2147=item OpenBSD 6
2148
2149OpenBSD 6 still does not support returning pid, gid or uid with SA_SIGINFO.
2150Make sure this is accounted for.
2151
2152=item FreeBSD
2153
2154t/uni/overload.t: Skip hanging test on FreeBSD.
2155
2156=back
2157
2158=head1 Internal Changes
2159
2160=over 4
2161
2162=item *
2163
95b17558 2164The C<op_class()> API function has been added. This is like the existing
2c8edc25 2165C<OP_CLASS()> macro, but can more accurately determine what struct an op
95b17558 2166has been allocated as. For example C<OP_CLASS()> might return
2c8edc25
S
2167C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
2168allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
2169C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
2170
2171=item *
2172
2173The output format of the C<op_dump()> function (as used by C<perl -Dx>)
2174has changed: it now displays an "ASCII-art" tree structure, and shows more
2175low-level details about each op, such as its address and class.
2176
2177=item *
2178
2179New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
2180been added, each with the
2181suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
2182parameter, giving an upper limit of how far into the string it is safe
2183to read. Using the old versions could cause attempts to read beyond the
2184end of the input buffer if the UTF-8 is not well-formed, and their use
2185now raises a deprecation warning. Details are at
2186L<perlapi/Character classification>.
2187
2188=item *
2189
2190Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
53799a91 2191deprecation warning since Perl 5.18. They now die.
2c8edc25
S
2192Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
2193
2194=item *
2195
2196Calling the functions C<utf8n_to_uvchr> and its derivatives, while
2197passing a string length of 0 is now asserted against in DEBUGGING
2198builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If
2199you have nothing to decode, you shouldn't call the decode function.
2200
2201=item *
2202
2203The functions C<utf8n_to_uvchr> and its derivatives now return the
2204Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong
2205malformation, and that malformation is allowed by the input parameters.
2206This malformation is where the UTF-8 looks valid syntactically, but
2207there is a shorter sequence that yields the same code point. This has
2208been forbidden since Unicode version 3.1.
2209
2210=item *
2211
2212The functions C<utf8n_to_uvchr> and its derivatives now accept an input
2213flag to allow the overflow malformation. This malformation is when the
2214UTF-8 may be syntactically valid, but the code point it represents is
2215not capable of being represented in the word length on the platform.
2216What "allowed" means in this case is that the function doesn't return an
2217error, and advances the parse pointer to beyond the UTF-8 in question,
2218but it returns the Unicode REPLACEMENT CHARACTER as the value of the
2219code point (since the real value is not representable).
2220
2221=item *
2222
2223The C<PADOFFSET> type has changed from being unsigned to signed, and
2224several pad-related variables such as C<PL_padix> have changed from being
2225of type C<I32> to type C<PADOFFSET>.
2226
2227=item *
2228
2229The function C<L<perlapi/utf8n_to_uvchr>> has been changed to not
2230abandon searching for other malformations when the first one is
2231encountered. A call to it thus can generate multiple diagnostics,
2232instead of just one.
2233
2234=item *
2235
2236A new function, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
2237use by modules that need to know the details of UTF-8 malformations
2238beyond pass/fail. Previously, the only ways to know why a sequence was
2239ill-formed was to capture and parse the generated diagnostics, or to do
2240your own analysis.
2241
2242=item *
2243
2244Several new functions for handling Unicode have been added to the API:
2245C<L<perlapi/is_strict_utf8_string>>,
2246C<L<perlapi/is_c9strict_utf8_string>>,
2247C<L<perlapi/is_utf8_string_flags>>,
2248C<L<perlapi/is_strict_utf8_string_loc>>,
2249C<L<perlapi/is_strict_utf8_string_loclen>>,
2250C<L<perlapi/is_c9strict_utf8_string_loc>>,
2251C<L<perlapi/is_c9strict_utf8_string_loclen>>,
2252C<L<perlapi/is_utf8_string_loc_flags>>,
2253C<L<perlapi/is_utf8_string_loclen_flags>>,
2254C<L<perlapi/is_utf8_fixed_width_buf_flags>>,
2255C<L<perlapi/is_utf8_fixed_width_buf_loc_flags>>,
2256C<L<perlapi/is_utf8_fixed_width_buf_loclen_flags>>.
2257
2258These functions are all extensions of the C<is_utf8_string_*()> functions,
2259that apply various restrictions to the UTF-8 recognized as valid.
2260
2261=item *
2262
2263A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
2264length and allocated size of the buffer in an C<SV>, growing the buffer if
2265necessary.
2266
2267=item *
2268
2269A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
2270like Perl-space C<$x = ''>, but with several optimisations.
2271
2272=item *
2273
2274All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
2275previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
2276that several parts of the internals had to be special-cased to accommodate
95b17558 2277it. This oddity's original motivation was to handle code like C<$x ||= 1>;
2c8edc25
S
2278that is now handled in a simpler way.
2279
2280=item *
2281
2282Several new internal C macros have been added that take a string literal as
2283arguments, alongside existing routines that take the equivalent value as two
95b17558 2284arguments, a character pointer and a length. The advantage of this is that
2c8edc25 2285the length of the string is calculated automatically, rather than having to
95b17558 2286be done manually. These routines are now used where appropriate across the
2c8edc25
S
2287entire codebase.
2288
2289=item *
2290
2291The code in F<gv.c> that determines whether a variable has a special meaning
2292to Perl has been simplified.
2293
2294=item *
2295
2296The C<DEBUGGING>-mode output for regex compilation and execution has been
2297enhanced.
2298
2299=item *
2300
2301Several macros and functions have been added to the public API for
2302dealing with Unicode and UTF-8-encoded strings. See
2303L<perlapi/Unicode Support>.
2304
2305=item *
2306
95b17558 2307Use C<my_strlcat()> in C<locale.c>. While C<strcat()> is safe in this context,
2c8edc25 2308some compilers were optimizing this to C<strcpy()> causing a porting test to
95b17558 2309fail that looks for unsafe code. Rather than fighting this, we just use
2c8edc25
S
2310C<my_strlcat()> instead.
2311
2312=item *
2313
2314Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
95b17558 2315been added. These are intended principally to implement the individual
2c8edc25
S
2316elements of a subroutine signature, plus any overall checking required.
2317
2318=item *
2319
2320Perl no longer panics when switching into some locales on machines with
2321buggy C<strxfrm()> implementations in their libc. [perl #121734]
2322
2323=item *
2324
2325Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
95b17558 2326default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
2c8edc25 2327This flag alters how the C<op_sibling> field is used in C<OP> structures,
53799a91 2328and has been available optionally since perl 5.22.
2c8edc25
S
2329
2330See L<perl5220delta/"Internal Changes"> for more details of what this
2331build option does.
2332
2333=item *
2334
2335The meanings of some internal SV flags have been changed
2336
2337OPpRUNTIME, SVpbm_VALID, SVpbm_TAIL, SvTAIL_on, SvTAIL_off, SVrepl_EVAL,
2338SvEVALED
2339
2340=item *
2341
2342Change C<hv_fetch(…, "…", …, …)> to C<hv_fetchs(…, "…", …)>
2343
2344The dual-life dists all use Devel::PPPort, so they can use this function even
2345though it was only added in 5.10.
2346
2347=back
2348
2349=head1 Selected Bug Fixes
2350
2351=over 4
2352
2353=item *
2354
2355C< $-{$name} > would leak an C<AV> on each access if the regular
2356expression had no named captures. The same applies to access to any
2357hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
2358#130822]
2359
2360=item *
2361
2362Attempting to use the deprecated variable C<$#> as the object in an
2363indirect object method call could cause a heap use after free or
2364buffer overflow. [perl #129274]
2365
2366=item *
2367
2368When checking for an indirect object method call in some rare cases
2369the parser could reallocate the line buffer but then continue to use
2370pointers to the old buffer. [perl #129190]
2371
2372=item *
2373
2374Supplying a glob as the format argument to L<perlfunc/formline> would
2375cause an assertion failure. [perl #130722]
2376
2377=item *
2378
2379Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
2380converted into a qr// operator, leaving extra elements on the stack to
2381confuse any surrounding expression. [perl #130705]
2382
2383=item *
2384
53799a91 2385Since 5.24 in some obscure cases, a regex which included code blocks
fce64130 2386from multiple sources (I<e.g.>, via embedded via qr// objects) could end up
2c8edc25
S
2387with the wrong current pad and crash or give weird results. [perl #129881]
2388
2389=item *
2390
2391Occasionally C<local()>s in a code block within a patterns weren't being
2392undone when the pattern matching backtracked over the code block.
2393[perl #126697]
2394
2395=item *
2396
2397Using C<substr()> to modify a magic variable could access freed memory
2398in some cases. [perl #129340]
2399
2400=item *
2401
2c8edc25
S
2402Under C<use utf8>, the entire Perl program is now checked that the UTF-8
2403is wellformed. This resolves [perl #126310].
2404
2405=item *
2406
2407The range operator C<..> on strings now handles its arguments correctly when in
2408the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
95b17558 2409feature. The previous behaviour was sufficiently unexpected that we believe no
2c8edc25
S
2410correct program could have made use of it.
2411
2412=item *
2413
2414The S<split> operator did not ensure enough space was allocated for
2415its return value in scalar context. It could then write a single
2416pointer immediately beyond the end of the memory block allocated for
2417the stack. [perl #130262]
2418
2419=item *
2420
2421Using a large code point with the C<W> pack template character with
2422the current output position aligned at just the right point could
2423cause a write a single zero byte immediately beyond the end of an
2424allocated buffer. [perl #129149]
2425
2426=item *
2427
2428Supplying the form picture argument as part of the form argument list
2429where the picture specifies modifying the argument could cause an
2430access to the new freed compiled form. [perl #129125]
2431
2432=item *
2433
2434Fix a problem with sort's build-in compare, where it would not sort
2435correctly with 64-bit integers, and non-long doubles. [perl #130335]
2436
2437=item *
2438
2439Fix issues with /(?{ ... E<lt>E<lt>EOF })/ that broke Method-Signatures. [perl #130398]
2440
2441=item *
2442
2443Fix a macro which caused syntax error on an EBCDIC build.
2444
2445=item *
2446
2447Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
2448
2449=item *
2450
2451Fixed an assertion failure with C<chop> and C<chomp>, which
2452could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
2453
2454=item *
2455
2456Fixed a comment skipping error under C</x>; it could stop skipping a
2457byte early, which could be in the middle of a UTF-8 character.
2458[perl #130495].
2459
2460=item *
2461
2462F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
2463
2464=item *
2465
2466Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
2467
2468=item *
2469
2470DragonFly BSD now has support for setproctitle(). [perl #130068].
2471
2472=item *
2473
2474Fix an assertion error which could be triggered when lookahead string
2475in patterns exceeded a minimum length. [perl #130522].
2476
2477=item *
2478
2479Only warn once per literal about a misplaced C<_>. [perl #70878].
2480
2481=item *
2482
2483Ensure range-start is set after error in C<tr///>. [perl #129342].
2484
2485=item *
2486
2487Don't read past start of string for unmatched backref; otherwise,
2488we may have heap buffer overflow. [perl #129377].
2489
2490=item *
2491
2492Properly recognize mathematical digit ranges starting at U+1D7E.
2493C<use re 'strict'> is supposed to warn if you use a range whose start
95b17558 2494and end digit aren't from the same group of 10. It didn't do that
2c8edc25
S
2495for five groups of mathematical digits starting at U+1D7E.
2496
2497=item *
2498
fce64130 2499A sub containing a "forward" declaration with the same name (I<e.g.>,
2c8edc25
S
2500C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2501#129090]
2502
2503=item *
2504
2505A crash in executing a regex with a floating UTF-8 substring against a
2506target string that also used UTF-8 has been fixed. [perl #129350]
2507
2508=item *
2509
2510Previously, a shebang line like C<#!perl -i u> could be erroneously
95b17558 2511interpreted as requesting the C<-u> option. This has been fixed. [perl
2c8edc25
S
2512#129336]
2513
2514=item *
2515
2516The regex engine was previously producing incorrect results in some rare
2517situations when backtracking past a trie that matches only one thing; this
2518showed up as capture buffers (C<$1>, C<$2>, etc) erroneously containing data
2519from regex execution paths that weren't actually executed for the final
2520match. [perl #129897]
2521
2522=item *
2523
2524Certain regexes making use of the experimental C<regex_sets> feature could
95b17558 2525trigger an assertion failure. This has been fixed. [perl #129322]
2c8edc25
S
2526
2527=item *
2528
fce64130 2529Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
2c8edc25
S
2530sometimes crash in addition to giving a syntax error. [perl #125679]
2531
2532=item *
2533
2534The parser could sometimes crash if a bareword came after C<evalbytes>.
2535[perl #129196]
2536
2537=item *
2538
2539Autoloading via a method call would warn erroneously ("Use of inherited
2540AUTOLOAD for non-method") if there was a stub present in the package into
2541which the invocant had been blessed. The warning is no longer emitted in
2542such circumstances. [perl #47047]
2543
2544=item *
2545
fce64130
KW
2546A sub containing with a "forward" declaration with the same name
2547(I<e.g.>,
2c8edc25
S
2548C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
2549#129090]
2550
2551=item *
2552
2553The use of C<splice> on arrays with nonexistent elements could cause other
2554operators to crash. [perl #129164]
2555
2556=item *
2557
2558Fixed case where C<re_untuit_start> will overshoot the length of a utf8
2559string. [perl #129012]
2560
2561=item *
2562
2563Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
2564checking that the I<current> C<cx> is the right type, and instead was always
2565checking the base C<cx> (effectively a noop). [perl #129029]
2566
2567=item *
2568
95b17558 2569Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
2c8edc25
S
2570maintains up to two pointers into the parser buffer, one of which can
2571become stale under the right conditions. [perl #129069]
2572
2573=item *
2574
2575Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
2576when it wasn't. [perl #129038]
2577
2578=item *
2579
2580Fixed place where regex was not setting the syntax error correctly.
2581[perl #129122]
2582
2583=item *
2584
2585The C<&.> operator (and the C<&> operator, when it treats its arguments as
2586strings) were failing to append a trailing null byte if at least one string
2587was marked as utf8 internally. Many code paths (system calls, regexp
2588compilation) still expect there to be a null byte in the string buffer
2589just past the end of the logical string. An assertion failure was the
2590result. [perl #129287]
2591
2592=item *
2593
2594Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
2595silently truncates the supplied path if it won't fit into the C<sun_path>
95b17558 2596member of C<sockaddr_un>. This may change in the future, but for now
2c8edc25
S
2597check the path in theC<sockaddr> matches the desired path, and skip if
2598it doesn't. [perl #128095]
2599
2600=item *
2601
95b17558 2602Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
2c8edc25
S
2603cases this is used in building error messages. [perl #128988]
2604
2605=item *
2606
2607Check for null PL_curcop in IN_LC() [perl #129106]
2608
2609=item *
2610
2611Fixed the parser error handling for an 'C<:attr(foo>' that does not have
2612an ending 'C<)>'.
2613
2614=item *
2615
2616Fix C<Perl_delimcpy()> to handle a backslash as last char, this
2617actually fixed two bugs, [perl #129064] and [perl #129176].
2618
2619=item *
2620
2621[perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to
2622prevent possible string overrun with invalid len in gv.c
2623
2624=item *
2625
2626Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
2627where the source and destination of the sort are the same plain array, are
95b17558 2628optimised to do less copying around. Two side-effects of this optimisation
2c8edc25
S
2629were that the contents of C<@a> as visible to to sort routine were
2630partially sorted, and under some circumstances accessing C<@a> during the
95b17558 2631sort could crash the interpreter. Both these issues have been fixed, and
2c8edc25
S
2632Sort functions see the original value of C<@a>.
2633
2634=item *
2635
2636Non-ASCII string delimiters are now reported correctly in error messages
2637for unterminated strings. [perl #128701]
2638
2639=item *
2640
2641C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
2642temporary value") erroneously in some cases, but has been fixed.
2643
2644=item *
2645
2646C<@DB::args> is now exempt from "used once" warnings. The warnings only
2647occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
2648multiple times.
2649
2650=item *
2651
2652The use of built-in arrays or hash slices in a double-quoted string no
2653longer issues a warning ("Possible unintended interpolation...") if the
2654variable has not been mentioned before. This affected code like
2655C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
2656C<@-> and C<@+> were already exempt from the warning.)
2657
2658=item *
2659
2660C<gethostent> and similar functions now perform a null check internally, to
2661avoid crashing with torsocks. This was a regression from 5.22. [perl
2662#128740]
2663
2664=item *
2665
2666C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
2667memory if the typeglob in question has never been accessed before.
2668
2669=item *
2670
2c8edc25
S
2671Mentioning the same constant twice in a row (which is a syntax error) no
2672longer fails an assertion under debugging builds. This was a regression
2673from 5.20. [perl #126482]
2674
2675=item *
2676
2677Many issues relating to C<printf "%a"> of hexadecimal floating point
2678were fixed. In addition, the "subnormals" (formerly known as "denormals")
2679floating point anumbers are now supported both with the plain IEEE 754
2680floating point numbers (64-bit or 128-bit) and the x86 80-bit
2681"extended precision". Note that subnormal hexadecimal floating
2682point literals will give a warning about "exponent underflow".
2683[perl #128843, #128889, #128890, #128893, #128909, #128919]
2684
2685=item *
2686
2687A regression in 5.24 with C<tr/\N{U+...}/foo/> when the code point was between
2688128 and 255 has been fixed. [perl #128734].
2689
2690=item *
2691
2692A regression from the previous development release, 5.23.3, where
2693compiling a regular expression could crash the interpreter has been
2694fixed. [perl #128686].
2695
2696=item *
2697
2698Use of a string delimiter whose code point is above 2**31 now works
2699correctly on platforms that allow this. Previously, certain characters,
2700due to truncation, would be confused with other delimiter characters
2701with special meaning (such as C<?> in C<m?...?>), resulting
2702in inconsistent behaviour. Note that this is non-portable,
2703and is based on Perl's extension to UTF-8, and is probably not
2704displayable nor enterable by any editor. [perl #128738]
2705
2706=item *
2707
2708C<@{x> followed by a newline where C<x> represents a control or non-ASCII
2709character no longer produces a garbled syntax error message or a crash.
2710[perl #128951]
2711
2712=item *
2713
2714An assertion failure with C<%: = 0> has been fixed.
2715L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
2716
2717=item *
2718
2719In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
2720that it would be treated as C<$foo."::".$bar>. The previous behavior, which
2721was to parse it as C<$foo:: . $bar>, has been restored.
2722L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
2723
2724=item *
2725
2726Since Perl 5.20, line numbers have been off by one when perl is invoked with
2727the B<-x> switch. This has been fixed.
2728L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
2729
2730=item *
2731
fce64130 2732Vivifying a subroutine stub in a deleted stash (I<e.g.>, C<delete $My::{"Foo::"};
2c8edc25
S
2733\&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
2734L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
2735
2736=item *
2737
2738Some obscure cases of subroutines and file handles being freed at the same time
2739could result in crashes, but have been fixed. The crash was introduced in Perl
27405.22.
2741L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
2742
2743=item *
2744
2745Code that looks for a variable name associated with an uninitialized value
2746could cause an assertion in cases where magic is involved, such as
2747C<$ISA[0][0]>. This has now been fixed.
2748L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
2749
2750=item *
2751
2752A crash caused by code generating the warning "Subroutine STASH::NAME
2753redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
2754fixed. In these cases, where the STASH is missing, the warning will now appear
2755as "Subroutine NAME redefined".
2756L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
2757
2758=item *
2759
2760Fixed an assertion triggered by some code that handles deprecated behavior in
fce64130 2761formats, I<e.g.>, in cases like this:
2c8edc25
S
2762
2763 format STDOUT =
2764 @
2765 0"$x"
2766
2767L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
2768
2769=item *
2770
2771A possible divide by zero in string transformation code on Windows has been
2772avoided, fixing a crash when collating an empty string.
2773L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
2774
2775=item *
2776
2777Some regular expression parsing glitches could lead to assertion failures with
e6abae1c 2778regular expressions such as C</(?E<lt>=/> and C</(?E<lt>!/>. This has now been fixed.
2c8edc25
S
2779L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
2780
2781=item *
2782
2783C< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
2784warn when syntax warnings are enabled. [perl #127333]
2785
2786=item *
2787
2788socket() now leaves the error code returned by the system in C<$!> on
2789failure. [perl #128316]
2790
2791=item *
2792
2793Assignment variants of any bitwise ops under the C<bitwise> feature would
2794crash if the left-hand side was an array or hash. [perl #128204]
2795
2796=item *
2797
2798C<require> followed by a single colon (as in C<foo() ? require : ...> is
2799now parsed correctly as C<require> with implicit $_, rather than
2800C<require "">. [perl #128307]
2801
2802=item *
2803
2804Scalar C<keys %hash> can now be assigned to consistently in all scalar
2805lvalue contexts. Previously it worked for some contexts but not others.
2806
2807=item *
2808
2809List assignment to C<vec> or C<substr> with an array or hash for its first
2810argument used to result in crashes or "Can't coerce" error messages at run
2811time, unlike scalar assignment, which would give an error at compile time.
2812List assignment now gives a compile-time error, too. [perl #128260]
2813
2814=item *
2815
2816Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
95b17558 2817and C<or>) were being compiled incorrectly in some cases. If the left-hand
2c8edc25
S
2818side consisted of either a negated bareword constant or a negated C<do {}>
2819block containing a constant expression, and the right-hand side consisted of
2820a negated non-foldable expression, one of the negations was effectively
95b17558
KW
2821ignored. The same was true of C<if> and C<unless> statement modifiers,
2822though with the left-hand and right-hand sides swapped. This long-standing
2c8edc25
S
2823bug has now been fixed. [perl #127952]
2824
2825=item *
2826
2827C<reset> with an argument no longer crashes when encountering stash entries
2828other than globs. [perl #128106]
2829
2830=item *
2831
2832Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
2833longer causes crashes. [perl #128086]
2834
2835=item *
2836
2837Handle SvIMMORTALs in LHS of list assign. [perl #129991]
2838
2839=item *
2840
2841[perl #130010] a5540cf breaks texinfo
2842
2843This involved user-defined Unicode properties.
2844
2845=item *
2846
2847Fix error message for unclosed C<\N{> in regcomp.
2848
2849An unclosed C<\N{> could give the wrong error message
2850C<"\N{NAME} must be resolved by the lexer">.
2851
2852=item *
2853
2854List assignment in list context where the LHS contained aggregates and
2855where there were not enough RHS elements, used to skip scalar lvalues.
2856Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
95b17558
KW
2857it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
2858returns C<($a,$b,$c)>. This can be seen in the following:
2c8edc25
S
2859
2860 sub inc { $_++ for @_ }
2861 inc(($a,$b,@c,$d) = (10))
2862
2863Formerly, the values of C<($a,$b,$d)> would be left as C<(11,undef,undef)>;
2864now they are C<(11,1,1)>.
2865
2866=item *
2867
2868[perl 129903]
2869
2870The basic problem is that code like this: /(?{ s!!! })/ can trigger infinite
2871recursion on the C stack (not the normal perl stack) when the last successful
95b17558 2872pattern in scope is itself. Since the C stack overflows this manifests as an
2c8edc25
S
2873untrappable error/segfault, which then kills perl.
2874
2875We avoid the segfault by simply forbidding the use of the empty pattern when it
2876would resolve to the currently executing pattern.
2877
2878=item *
2879
2880[perl 128997] Avoid reading beyond the end of the line buffer when there's a
2881short UTF-8 character at the end.
2882
2883=item *
2884
2885[perl 129950] fix firstchar bitmap under utf8 with prefix optimisation.
2886
2887=item *
2888
2889[perl 129954] Carp/t/arg_string.t: be liberal in f/p formats.
2890
2891=item *
2892
2893[perl 129928] make do "a\0b" fail silently instead of throwing.
2894
2895=item *
2896
2897[perl 129130] make chdir allocate the stack it needs.
2898
2899=back
2900
2901=head1 Known Problems
2902
2903=over 4
2904
2905=item *
2906
2907Some modules have been broken by the L<context stack rework|/Internal Changes>.
2908These modules were relying on non-guaranteed implementation details in perl.
2909Their maintainers have been informed, and should contact perl5-porters for
2910advice if needed. Below is a subset of these modules:
2911
2912=over 4
2913
2914=item * L<Algorithm::Permute>
2915
2916=item * L<Coro>
2917
53799a91 2918L<Coro> and perl 5.22 were already incompatible due to a change in the perl,
2c8edc25
S
2919and the reworking on the perl context stack creates a further incompatibility.
2920perl5-porters has L<discussed the issue on the mailing
2921list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
2922
2923=item * L<Data::Alias>
2924
2925=item * L<RPerl>
2926
2927=item * L<Scope::Upper>
2928
2929=item * L<TryCatch>
2930
2931=back
2932
2933=item *
2934
53799a91 2935The module L<lexical::underscore> no longer works on Perl 5.24, because perl
2c8edc25
S
2936no longer has a lexical C<$_>!
2937
2938=item *
2939
53799a91 2940C<mod_perl> has been patched for compatibility for v5.22 and later but no
2c8edc25
S
2941release has been made. The relevant patch (and other changes) can be found in
2942their source code repository, L<mirrored at
2943GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
2944
2945=back
2946
2947=head1 Errata From Previous Releases
2948
2949=over 4
2950
2951=item *
2952
ee8180b8 2953Parsing bad POSIX charclasses no longer leaks memory.
2c8edc25
S
2954L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
2955
2956=item *
2957
53799a91 2958Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
2c8edc25
S
2959L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
2960
2961=back
2962
2963=head1 Obituary
2964
2965Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
95b17558 2966member, has passed away on August 10, 2016. He will be remembered and
c94c0e4f 2967missed by all those who he came in contact with, and enriched with his
2c8edc25
S
2968intellect, wit, and spirit.
2969
c94c0e4f 2970It is with great sadness that we also note Kip Hampton's passing. Probably
2c8edc25
S
2971best known as the author of the Perl & XML column on XML.com, he was a
2972core contributor to AxKit, an XML server platform that became an Apache
95b17558
KW
2973Foundation project. He was a frequent speaker in the early days at
2974OSCON, and most recently at YAPC::NA in Madison. He was frequently on
2c8edc25
S
2975irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
2976group responsible for YAPC::NA Asheville in 2011.
a049258c 2977
2c8edc25
S
2978Kip and his constant contributions to the community will be greatly
2979missed.
a049258c
S
2980
2981=head1 Acknowledgements
2e0dcc12 2982
0cc8c746 2983Perl 5.26.0 represents approximately 12 months of development since Perl 5.24.0
c2948ced 2984and contains approximately 370,000 lines of changes across 2,600 files from 86
0cc8c746
S
2985authors.
2986
2987Excluding auto-generated files, documentation and release tools, there were
2988approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
2989
2990Perl continues to flourish into its third decade thanks to a vibrant community
95b17558 2991of users and developers. The following people are known to have contributed the
ad543fb2 2992improvements that became Perl 5.26.0:
0cc8c746
S
2993
2994Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
2995König, Andreas Voegele, Andrew Fresh, Andy Lester, Aristotle Pagaltzis, Chad
2996Granum, Chase Whitener, Chris 'BinGOs' Williams, Chris Lamb, Christian Hansen,
2997Christian Millour, Colin Newell, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan
c2948ced
S
2998Collins, Daniel Dragan, Dave Cross, Dave Rolsky, David Golden, David H.
2999Gutteridge, David Mitchell, Dominic Hargreaves, Doug Bell, E. Choroba, Ed Avis,
3000Father Chrysostomos, François Perrad, Hauke D, H.Merijn Brand, Hugo van der
3001Sanden, Ivan Pozdeev, James E Keenan, James Raspass, Jarkko Hietaniemi, Jerry
3002D. Hedden, Jim Cromie, J. Nick Koston, John Lightsey, Karen Etheridge, Karl
3003Williamson, Leon Timmermans, Lukas Mai, Matthew Horsfall, Maxwell Carey, Misty
3004De Meo, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Paul
3005Marquess, Peter Avalos, Petr Písař, Pino Toscano, Rafael Garcia-Suarez, Reini
3006Urban, Renee Baecker, Ricardo Signes, Richard Levitte, Rick Delaney, Salvador
3007Fandiño, Samuel Thibault, Sawyer X, Sébastien Aperghis-Tramoni, Sergey
3008Aleynikov, Shlomi Fish, Smylers, Stefan Seifert, Steffen Müller, Stevan
3009Little, Steve Hay, Steven Humphrey, Sullivan Beck, Theo Buehler, Thomas Sibley,
3010Todd Rinaldo, Tomasz Konojacki, Tony Cook, Unicode Consortium, Yaroslav Kuzmin,
3011Yves Orton, Zefram.
0cc8c746
S
3012
3013The list above is almost certainly incomplete as it is automatically generated
95b17558 3014from version control history. In particular, it does not include the names of
0cc8c746
S
3015the (very much appreciated) contributors who reported issues to the Perl bug
3016tracker.
3017
3018Many of the changes included in this version originated in the CPAN modules
95b17558 3019included in Perl's core. We're grateful to the entire CPAN community for
0cc8c746
S
3020helping Perl to flourish.
3021
3022For a more complete list of all of Perl's historical contributors, please see
3023the F<AUTHORS> file in the Perl source distribution.
f5b73711 3024
44691e6f
AB
3025=head1 Reporting Bugs
3026
2c8edc25
S
3027If you find what you think is a bug, you might check the articles recently
3028posted to the comp.lang.perl.misc newsgroup and the perl bug database at
3029L<https://rt.perl.org/> . There may also be information at
4b8803f0 3030L<http://www.perl.org/> , the Perl Home Page.
44691e6f 3031
e08634c5
SH
3032If you believe you have an unreported bug, please run the L<perlbug> program
3033included with your release. Be sure to trim your bug down to a tiny but
3034sufficient test case. Your bug report, along with the output of C<perl -V>,
7c825fca 3035will be sent off to C<perlbug@perl.org> to be analysed by the Perl porting team.
44691e6f 3036
87c118b9
DM
3037If the bug you are reporting has security implications which make it
3038inappropriate to send to a publicly archived mailing list, then see
c0ea3294
SH
3039L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
3040for details of how to report the issue.
44691e6f
AB
3041
3042=head1 SEE ALSO
3043
e08634c5
SH
3044The F<Changes> file for an explanation of how to view exhaustive details on
3045what changed.
44691e6f
AB
3046
3047The F<INSTALL> file for how to build Perl.
3048
3049The F<README> file for general stuff.
3050
3051The F<Artistic> and F<Copying> files for copyright information.
3052
3053=cut