5 perl5253delta - what is new for perl v5.25.3
9 This document describes differences between the 5.25.2 release and the 5.25.3
12 If you are upgrading from an earlier release such as 5.25.1, first read
13 L<perl5252delta>, which describes differences between 5.25.1 and 5.25.2.
15 =head1 Core Enhancements
17 =head2 Unicode 9.0 is now supported
19 A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
20 Modules that are shipped with core Perl but not maintained by p5p do not
21 necessarily support Unicode 9.0. L<Unicode::Normalize> does work on 9.0.
23 =head2 Use of C<\p{I<script>}> uses the improved Script_Extensions property
25 Unicode 6.0 introduced an improved form of the Script (C<sc>) property, and
26 called it Script_Extensions (C<scx>). As of now, Perl uses this improved
27 version when a property is specified as just C<\p{I<script>}>. The meaning of
28 compound forms, like C<\p{sc=I<script>}> are unchanged. This should make
29 programs be more accurate when determining if a character is used in a given
30 script, but there is a slight chance of breakage for programs that very
31 specifically needed the old behavior. See L<perlunicode/Scripts>.
33 =head2 Declaring a reference to a variable
35 As an experimental feature, Perl now allows the referencing operator to come
36 after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
37 L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
38 be enabled with C<use feature 'declared_refs'>. It is experimental, and will
39 warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
40 It is intended mainly for use in assignments to references. For example:
42 use experimental 'refaliasing', 'declared_refs';
45 See L<perlref/Assigning to References> for slightly more detail.
47 =head1 Incompatible Changes
49 =head2 C<${^ENCODING}> has been removed
51 Consequently, the L<encoding> pragma's default mode is no longer supported. If
52 you still need to write your source code in encodings other than UTF-8, use a
53 source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
56 =head2 C<scalar(%hash)> return signature changed
58 The value returned for C<scalar(%hash)> will no longer show information about
59 the buckets allocated in the hash. It will simply return the count of used
60 keys. It is thus equivalent to C<0+keys(%hash)>.
62 A form of backwards compatibility is provided via C<Hash::Util::bucket_ratio()>
63 which provides the same behavior as C<scalar(%hash)> provided prior to Perl
66 =head1 Modules and Pragmata
68 =head2 Updated Modules and Pragmata
74 L<bignum> has been upgraded from version 0.42 to 0.43.
78 L<Data::Dumper> has been upgraded from version 2.160 to 2.161.
82 L<Devel::PPPort> has been upgraded from version 3.32 to 3.35.
86 L<Encode> has been upgraded from version 2.80 to 2.84.
90 L<encoding> has been upgraded from version 2.17 to 2.17_01.
92 This module's default mode is no longer supported as of Perl 5.25.3. It now
93 dies when imported, unless the C<Filter> option is being used.
97 L<encoding::warnings> has been upgraded from version 0.12 to 0.13.
99 This module is no longer supported as of Perl 5.25.3. It emits a warning to
100 that effect and then does nothing.
104 L<ExtUtils::ParseXS> has been upgraded from version 3.32 to 3.33.
108 L<ExtUtils::Typemaps> has been upgraded from version 3.32 to 3.33.
112 L<feature> has been upgraded from version 1.44 to 1.45.
116 L<Hash::Util> has been upgraded from version 0.19 to 0.20.
120 L<Math::BigInt> has been upgraded from version 1.999715 to 1.999726.
124 L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.42.
128 L<Math::BigRat> has been upgraded from version 0.260802 to 0.260804.
132 L<Module::CoreList> has been upgraded from version 5.20160620 to 5.20160720.
136 L<Parse::CPAN::Meta> has been upgraded from version 1.4417 to 1.4422.
140 L<Perl::OSType> has been upgraded from version 1.009 to 1.010.
144 L<Test::Simple> has been upgraded from version 1.302026 to 1.302045.
148 L<Time::HiRes> has been upgraded from version 1.9734 to 1.9739.
152 L<Unicode::UCD> has been upgraded from version 0.65 to 0.66.
156 L<version> has been upgraded from version 0.9916 to 0.9917.
160 L<warnings> has been upgraded from version 1.36 to 1.37.
164 L<XSLoader> has been upgraded from version 0.21 to 0.22, fixing a security hole
165 in which binary files could be loaded from a path outside of
166 L<C<@INC>|perlvar/@INC>.
172 =head2 Changes to Existing Documentation
174 =head3 L<perldata> and L<perltie>
180 Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
181 signature changed> above.
185 =head3 L<perlexperiment> and L<perlref>
191 Documented new feature: See L</Declaring a reference to a variable> above.
201 Clarified documentation of L<C<seek()>|perlfunc/seek>,
202 L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>.
203 L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
207 Removed obsolete documentation of L<C<study()>|perlfunc/study>.
211 =head3 L<perlunicode>
217 Documented change to C<\p{I<script>}> to now use the improved Script_Extensions
218 property. See L</Use of \p{script} uses the improved Script_Extensions
223 Updated the text to correspond with changes in Unicode UTS#18, concerning
224 regular expressions, and Perl compatibility with what it says.
234 Removed obsolete documentation of C<${^ENCODING}>. See L</${^ENCODING} has
241 The following additions or changes have been made to diagnostic output,
242 including warnings and fatal error messages. For the complete list of
243 diagnostic messages, see L<perldiag>.
245 =head2 New Diagnostics
253 L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
255 (F) To declare references to variables, as in C<my \%x>, you must first enable
258 no warnings "experimental::declared_refs";
259 use feature "declared_refs";
269 L<Declaring references is experimental|perldiag/"Declaring references is experimental">
271 (S experimental::declared_refs) This warning is emitted if you use a reference
272 constructor on the right-hand side of C<my()>, C<state()>, C<our()>, or
273 C<local()>. Simply suppress the warning if you want to use the feature, but
274 know that in doing so you are taking the risk of using an experimental feature
275 which may change or be removed in a future Perl version:
277 no warnings "experimental::declared_refs";
278 use feature "declared_refs";
283 L<C<${^ENCODING}> is no longer supported|perldiag/"${^ENCODING} is no longer supported">
285 (D deprecated) The special variable C<${^ENCODING}>, formerly used to implement
286 the C<encoding> pragma, is no longer supported as of Perl 5.26.0.
290 =head1 Configuration and Compilation
296 F<Configure> now aborts if both "-Duselongdouble" and "-Dusequadmath" are
298 L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
302 Fixed a bug in which F<Configure> could append "-quadmath" to the archname even
303 if it was already present.
304 L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
308 Clang builds with "-DPERL_GLOBAL_STRUCT" or "-DPERL_GLOBAL_STRUCT_PRIVATE" have
309 been fixed (by disabling Thread Safety Analysis for these configurations).
319 A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
320 "Declaring a reference to a variable".
324 A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
325 generated by bracketed character classes are as expected.
329 =head1 Platform Support
331 =head2 Platform-Specific Notes
337 VAX floating point formats are now supported.
341 =head1 Selected Bug Fixes
347 An assertion failure with C<%: = 0> has been fixed.
348 L<[perl #128238]|https://rt.perl.org/Public/Bug/Display.html?id=128238>
352 In Perl 5.18, the parsing of C<"$foo::$bar"> was accidentally changed, such
353 that it would be treated as C<$foo."::".$bar>. The previous behavior, which
354 was to parse it as C<$foo:: . $bar>, has been restored.
355 L<[perl #128478]|https://rt.perl.org/Public/Bug/Display.html?id=128478>
359 Since Perl 5.20, line numbers have been off by one when perl is invoked with
360 the B<-x> switch. This has been fixed.
361 L<[perl #128508]|https://rt.perl.org/Public/Bug/Display.html?id=128508>
365 Vivifying a subroutine stub in a deleted stash (e.g., C<delete $My::{"Foo::"};
366 \&My::Foo::foo>) no longer crashes. It had begun crashing in Perl 5.18.
367 L<[perl #128532]|https://rt.perl.org/Public/Bug/Display.html?id=128532>
371 Some obscure cases of subroutines and file handles being freed at the same time
372 could result in crashes, but have been fixed. The crash was introduced in Perl
374 L<[perl #128597]|https://rt.perl.org/Public/Bug/Display.html?id=128597>
378 Code that looks for a variable name associated with an uninitialized value
379 could cause an assertion in cases where magic is involved, such as
380 C<$ISA[0][0]>. This has now been fixed.
381 L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
385 A crash caused by code generating the warning "Subroutine STASH::NAME
386 redefined" in cases such as C<sub P::f{} undef *P::; *P::f =sub{};> has been
387 fixed. In these cases, where the STASH is missing, the warning will now appear
388 as "Subroutine NAME redefined".
389 L<[perl #128257]|https://rt.perl.org/Public/Bug/Display.html?id=128257>
393 Fixed an assertion triggered by some code that handles deprecated behavior in
394 formats, e.g. in cases like this:
400 L<[perl #128255]|https://rt.perl.org/Public/Bug/Display.html?id=128255>
404 A possible divide by zero in string transformation code on Windows has been
405 avoided, fixing a crash when collating an empty string.
406 L<[perl #128618]|https://rt.perl.org/Public/Bug/Display.html?id=128618>
410 Some regular expression parsing glitches could lead to assertion failures with
411 regular expressions such as C</(?<=/> and C</(?<!/>. This has now been fixed.
412 L<[perl #128170]|https://rt.perl.org/Public/Bug/Display.html?id=128170>
416 =head1 Errata From Previous Releases
422 Parsing bad POSIX charclasses no longer leaks memory. This was fixed in Perl
424 L<[perl #128313]|https://rt.perl.org/Public/Bug/Display.html?id=128313>
428 Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.0.
429 L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
433 =head1 Acknowledgements
435 Perl 5.25.3 represents approximately 4 weeks of development since Perl 5.25.2
436 and contains approximately 67,000 lines of changes across 510 files from 25
439 Excluding auto-generated files, documentation and release tools, there were
440 approximately 40,000 lines of changes to 290 .pm, .t, .c and .h files.
442 Perl continues to flourish into its third decade thanks to a vibrant community
443 of users and developers. The following people are known to have contributed
444 the improvements that became Perl 5.25.3:
446 Aaron Crane, Ævar Arnfjörð Bjarmason, Alex Vandiver, Aristotle Pagaltzis,
447 Chad Granum, Chris 'BinGOs' Williams, Chris Lamb, Craig A. Berry, Dan Collins,
448 David Mitchell, Father Chrysostomos, H.Merijn Brand, Jarkko Hietaniemi, Karl
449 Williamson, Lukas Mai, Matthew Horsfall, Salvador Fandiño, Sawyer X,
450 Sébastien Aperghis-Tramoni, Steffen Müller, Steve Hay, Todd Rinaldo, Tony
451 Cook, Unicode Consortium, Yves Orton.
453 The list above is almost certainly incomplete as it is automatically generated
454 from version control history. In particular, it does not include the names of
455 the (very much appreciated) contributors who reported issues to the Perl bug
458 Many of the changes included in this version originated in the CPAN modules
459 included in Perl's core. We're grateful to the entire CPAN community for
460 helping Perl to flourish.
462 For a more complete list of all of Perl's historical contributors, please see
463 the F<AUTHORS> file in the Perl source distribution.
465 =head1 Reporting Bugs
467 If you find what you think is a bug, you might check the perl bug database at
468 L<https://rt.perl.org/> . There may also be information at
469 L<http://www.perl.org/> , the Perl Home Page.
471 If you believe you have an unreported bug, please run the L<perlbug> program
472 included with your release. Be sure to trim your bug down to a tiny but
473 sufficient test case. Your bug report, along with the output of C<perl -V>,
474 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
476 If the bug you are reporting has security implications which make it
477 inappropriate to send to a publicly archived mailing list, then see
478 L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION> for details of how to
483 The F<Changes> file for an explanation of how to view exhaustive details on
486 The F<INSTALL> file for how to build Perl.
488 The F<README> file for general stuff.
490 The F<Artistic> and F<Copying> files for copyright information.