5 perl5340delta - what is new for perl v5.34.0
9 This document describes differences between the 5.32.0 release and the 5.34.0
12 If you are upgrading from an earlier release such as 5.30.0, first read
13 L<perl5320delta>, which describes differences between 5.30.0 and 5.32.0.
15 =head1 Core Enhancements
17 =head2 Experimental Try/Catch Syntax
19 An initial experimental attempt at providing C<try>/C<catch> notation has
28 warn "An error occurred: $e";
31 For more information, see L<perlsyn/"Try Catch Exception Handling">.
33 =head2 C<qr/{,n}/> is now accepted
35 An empty lower bound is now accepted for regular expression quantifiers,
36 like C<m/x{,3}/> meaning C<m/x{0,3}/>
41 =head2 Blanks freely allowed within but adjacent to curly braces
43 (in double-quotish contexts and regular expression patterns)
45 This means you can write things like S<C<\x{ FFFC }>> if you like. This
46 applies to all such constructs, namely C<\b{}>, C<\g{}>, C<\k{}>,
47 C<\N{}>, C<\o{}>, and C<\x{}>; as well as the regular expression
48 quantifier C<{I<m>,I<n>}>. C<\p{}> and C<\P{}> retain their
49 already-existing, even looser, rules mandated by the Unicode standard
50 (see L<perluniprops/Properties accessible through \p{} and \P{}>).
52 This ability is in effect regardless of the presence of the C</x>
53 regular expression pattern modifier.
55 Additionally, the comma in a regular expression braced quantifier may
56 have blanks (tabs or spaces) before and/or after the comma, like
59 =head2 New octal syntax C<0oI<ddddd>>
61 It is now possible to specify octal literals with C<0o> prefixes,
62 as in C<0o123_456>, parallel to the existing construct to specify
63 hexadecimal literal C<0xI<ddddd>> and binary literal C<0bI<ddddd>>.
64 Also, the builtin C<oct()> function now accepts this new syntax.
66 See L<perldata/Scalar value constructors> and L<perlfunc/oct EXPR>.
68 =head1 Performance Enhancements
74 Fix a memory leak in RegEx
75 [L<GH #18604|https://github.com/Perl/perl5/issues/18604>]
79 =head1 Modules and Pragmata
81 =head2 New Modules and Pragmata
87 L<ExtUtils::PL2Bat> 0.004 has been added to the Perl core.
89 This module is a generalization of the C<pl2bat> script. It being a script has
90 led to at least two forks of this code; this module will unify them under one
91 implementation with tests.
95 =head2 Updated Modules and Pragmata
101 L<Archive::Tar> has been upgraded from version 2.36 to 2.38.
105 L<autodie> has been upgraded from version 2.32 to 2.34.
109 L<B> has been upgraded from version 1.80 to 1.82.
113 L<B::Deparse> has been upgraded from version 1.54 to 1.56.
117 L<bytes> has been upgraded from version 1.07 to 1.08.
121 L<Carp> has been upgraded from version 1.50 to 1.52.
125 L<Compress::Raw::Bzip2> has been upgraded from version 2.093 to 2.101.
129 L<Compress::Raw::Zlib> has been upgraded from version 2.093 to 2.101.
133 L<Config::Perl::V> has been upgraded from version 0.32 to 0.33.
137 L<CPAN> has been upgraded from version 2.27 to 2.28.
141 L<Data::Dumper> has been upgraded from version 2.174 to 2.179.
145 L<DB> has been upgraded from version 1.58 to 1.59.
149 L<DB_File> has been upgraded from version 1.853 to 1.855.
153 L<Devel::Peek> has been upgraded from version 1.28 to 1.30.
157 L<Devel::PPPort> has been upgraded from version 3.57 to 3.62.
159 New C<PERL_VERSION_*> comparison macros are now available.
161 C<ppport.h --api-info> no longer includes non-API info unless that is the only
166 L<Digest> has been upgraded from version 1.17_01 to 1.19.
170 L<Digest::MD5> has been upgraded from version 2.55_01 to 2.58.
174 L<DynaLoader> has been upgraded from version 1.47 to 1.50.
178 L<Encode> has been upgraded from version 3.06 to 3.08.
182 L<Env> has been upgraded from version 1.04 to 1.05.
186 L<Errno> has been upgraded from version 1.30 to 1.33.
190 L<experimental> has been upgraded from version 0.020 to 0.024.
194 L<Exporter> has been upgraded from version 5.74 to 5.76.
198 L<ExtUtils::CBuilder> has been upgraded from version 0.280234 to 0.280236.
202 L<ExtUtils::Install> has been upgraded from version 2.14 to 2.20.
206 L<ExtUtils::MakeMaker> has been upgraded from version 7.44 to 7.62.
210 L<ExtUtils::Manifest> has been upgraded from version 1.72 to 1.73.
214 L<ExtUtils::Miniperl> has been upgraded from version 1.09 to 1.10.
218 L<ExtUtils::ParseXS> has been upgraded from version 3.40 to 3.43.
222 L<ExtUtils::Typemaps> has been upgraded from version 3.38 to 3.43.
226 L<Fcntl> has been upgraded from version 1.13 to 1.14.
230 L<feature> has been upgraded from version 1.58 to 1.64.
232 Added the default enabled C<bareword_filehandles> feature.
234 A new L<multidimensional|feature/"The 'multidimensional' feature">
235 feature has been added, which is enabled by
236 default but allows turning off L<multi-dimensional array
237 emulation|perldata/Multi-dimensional array emulation>.
241 L<File::Copy> has been upgraded from version 2.34 to 2.35.
245 L<File::Fetch> has been upgraded from version 0.56 to 1.00.
249 L<File::Find> has been upgraded from version 1.37 to 1.39.
253 L<File::Path> has been upgraded from version 2.16 to 2.18.
257 L<File::Spec> has been upgraded from version 3.78 to 3.80.
261 L<File::Temp> has been upgraded from version 0.2309 to 0.2311.
265 L<Filter::Util::Call> has been upgraded from version 1.59 to 1.60.
269 L<FindBin> has been upgraded from version 1.51 to 1.52.
273 L<GDBM_File> has been upgraded from version 1.18 to 1.19.
275 New functions and compatibility for newer versions of GDBM.
276 [L<GH #18435|https://github.com/Perl/perl5/pull/18435>]
280 L<Getopt::Long> has been upgraded from version 2.51 to 2.52.
284 L<Getopt::Std> has been upgraded from version 1.12 to 1.13.
288 L<Hash::Util> has been upgraded from version 0.23 to 0.25.
292 L<Hash::Util::FieldHash> has been upgraded from version 1.20 to 1.21.
296 L<I18N::LangTags> has been upgraded from version 0.44 to 0.45.
300 L<if> has been upgraded from version 0.0608 to 0.0609.
304 L<IO> has been upgraded from version 1.43 to 1.46.
306 IO::Socket now stores error messages in C<$IO::Socket::errstr>, in
307 addition to in C<$@>.
309 The C<error> method now reports the error state for both the input and
310 output streams for sockets and character devices. Similarly
311 C<clearerr> now clears the error state for both streams.
313 A spurious error reported for regular file handles has been
314 fixed in L<IO::Handle>.
315 [L<GH #18019|https://github.com/Perl/perl5/issues/18019>]
319 IO-Compress has been upgraded from version 2.093 to 2.102.
321 bin/zipdetails version 2.02
325 L<IO::Socket::IP> has been upgraded from version 0.39 to 0.41.
329 L<IO::Zlib> has been upgraded from version 1.10 to 1.11.
333 L<IPC::SysV> has been upgraded from version 2.07 to 2.09.
337 L<JSON::PP> has been upgraded from version 4.04 to 4.06.
341 The libnet distribution has been upgraded from version 3.11 to 3.13.
345 L<locale> has been upgraded from version 1.09 to 1.10.
349 L<Math::Complex> has been upgraded from version 1.5901 to 1.5902.
353 L<MIME::Base64> has been upgraded from version 3.15 to 3.16.
357 L<Module::CoreList> has been upgraded from version 5.20200620 to 5.20210520.
361 L<Module::Load> has been upgraded from version 0.34 to 0.36.
365 L<Module::Load::Conditional> has been upgraded from version 0.70 to 0.74.
369 L<mro> has been upgraded from version 1.23 to 1.25_001.
373 L<Net::Ping> has been upgraded from version 2.72 to 2.74.
377 L<NEXT> has been upgraded from version 0.67_01 to 0.68.
381 L<ODBM_File> has been upgraded from version 1.16 to 1.17.
385 L<Opcode> has been upgraded from version 1.47 to 1.50.
389 L<overload> has been upgraded from version 1.31 to 1.33.
393 L<perlfaq> has been upgraded from version 5.20200523 to 5.20210411.
397 L<PerlIO::encoding> has been upgraded from version 0.28 to 0.30.
401 L<PerlIO::mmap> has been upgraded from version 0.016 to 0.017.
405 L<PerlIO::scalar> has been upgraded from version 0.30 to 0.31.
409 L<PerlIO::via::QuotedPrint> has been upgraded from version 0.08 to 0.09.
413 L<Pod::Checker> has been upgraded from version 1.73 to 1.74.
417 L<Pod::Html> has been upgraded from version 1.25 to 1.27.
421 L<Pod::Simple> has been upgraded from version 3.40 to 3.42.
425 L<Pod::Usage> has been upgraded from version 1.69 to 2.01.
429 L<POSIX> has been upgraded from version 1.94 to 1.97.
431 POSIX::signbit() behaviour has been improved.
432 [L<GH #18441|https://github.com/Perl/perl5/pull/18441>]
434 Documentation for C<asctime> clarifies that the result is always in English.
435 (Use C<strftime> for a localized result.)
439 L<re> has been upgraded from version 0.40 to 0.41.
441 (See under L</Internal Changes> for more information.)
445 L<Safe> has been upgraded from version 2.41 to 2.43.
449 L<Socket> has been upgraded from version 2.029 to 2.031.
453 L<Storable> has been upgraded from version 3.21 to 3.23.
457 L<strict> has been upgraded from version 1.11 to 1.12.
461 L<subs> has been upgraded from version 1.03 to 1.04.
465 L<Symbol> has been upgraded from version 1.08 to 1.09.
469 L<Test::Harness> has been upgraded from version 3.42 to 3.43.
473 L<Test::Simple> has been upgraded from version 1.302175 to 1.302183.
477 L<Text::Balanced> has been upgraded from version 2.03 to 2.04.
481 L<threads> has been upgraded from version 2.25 to 2.26.
485 L<threads::shared> has been upgraded from version 1.61 to 1.62.
489 L<Tie::RefHash> has been upgraded from version 1.39 to 1.40.
493 L<Time::HiRes> has been upgraded from version 1.9764 to 1.9767.
497 L<Time::Local> has been upgraded from version 1.28 to 1.30.
501 L<Unicode::Collate> has been upgraded from version 1.27 to 1.29.
505 L<Unicode::Normalize> has been upgraded from version 1.27 to 1.28.
509 L<utf8> has been upgraded from version 1.22 to 1.24.
513 L<version> has been upgraded from version 0.9924 to 0.9928.
517 L<warnings> has been upgraded from version 1.47 to 1.51.
521 L<Win32> has been upgraded from version 0.53 to 0.57.
523 Fix calling convention for C<PFNRegGetValueA>.
525 Added C<Win32::IsSymlinkCreationAllowed()>,
526 C<Win32::IsDeveloperModeEnabled()>, and C<Win32::GetProcessPrivileges()>.
528 Removed old code for versions before Windows 2000.
532 L<XS::APItest> has been upgraded from version 1.09 to 1.16.
536 L<XS::Typemap> has been upgraded from version 0.17 to 0.18.
542 =head2 New Documentation
544 =head3 L<perldocstyle>
546 This document is a guide for the authorship and maintenance of the
547 documentation that ships with Perl.
551 This document describes the goals, scope, system, and rules for Perl's new
554 Other pod files, most notably L<perlpolicy>, were amended to reflect
557 =head2 Changes to Existing Documentation
559 We have attempted to update the documentation to reflect the changes
560 listed in this document. If you find any we have missed, open an issue
561 at L<https://github.com/Perl/perl5/issues>.
563 Additionally, the following selected changes have been made:
569 L<perlapi>, L<perlguts>, L<perlxs>, and L<perlxstut> now prefer C<SvPVbyte>
574 References to B<Pumpking> have been replaced with a more accurate term or
575 B<Steering Council> where appropriate.
579 B<The Perl Steering Council> is now the fallback contact for security issues.
589 Efforts continue in improving the presentation of this document, and to
590 document more API elements.
594 =head3 L<perlcommunity>
600 The freenode IRC URL has been updated.
604 =head3 L<perldebguts>
610 Corrected the description of the scalar C<< ${"_<$filename"} >>
621 Now documents additional examples of "not imported" warnings.
631 The Perl FAQ was updated to CPAN version 5.20201107 with minor
642 L<my()|perlfunc/my> and L<state()|perlfunc/state> now explicitly warn
643 the reader that lexical variables should typically not be redeclared
644 within the same scope or statement.
645 [L<GH #18389|https://github.com/Perl/perl5/issues/18389>]
649 The L<localtime|perlfunc/localtime> entry has been improved and now
650 also states that the result of the function is always in English.
654 L<msgsnd()|perlfunc/msgsnd> documented a length field included in the
655 packed C<MSG> parameter to C<msgsnd()>, but there was no such field.
656 C<MSG> contains only the type and the message content.
660 Better explanation of what happens when C<sleep> is called with a zero or
665 Simplify the C<split()> documentation by removing the C<join()>s from the
667 [L<GH #18676|https://github.com/Perl/perl5/issues/18676>]
677 document how to create a remote-tracking branch for every PR
681 document how to get a PR as a local branch
691 L<perlguts> now explains in greater detail the need to consult C<SvUTF8>
692 when calling C<SvPV> (or variants). A new "How do I pass a Perl string to a C
693 library?" section in the same document discusses when to use which style of
694 macro to read an SV's string value.
698 Corrected C<my_rpeep> example in perlguts.
702 A section has been added on the formatted printing of special sizes.
712 The C<< <> >> and C<<< <<>> >>> operators are commonly referred to as
713 the diamond and double diamond operators respectively, but that wasn't
714 mentioned previously in their documentation.
718 Document range op behavior change.
722 =head3 L<perlpacktut>
728 Incorrect variables used in an example have been fixed.
738 Document that caller() does not see try{} blocks
742 A new example shows how a lexical C<my> variable can be declared
743 during the initialization of a C<for> loop.
753 Fix description of what Perl does with unencoded strings
759 The following additions or changes have been made to diagnostic output,
760 including warnings and fatal error messages. For the complete list of
761 diagnostic messages, see L<perldiag>.
763 =head2 New Diagnostics
771 L<Bareword filehandle "%s" not allowed under 'no feature "bareword_filehandles"'|perldiag/"Bareword filehandle "%s" not allowed under 'no feature "bareword_filehandles"'">
773 This accompanies the new
774 L<bareword_filehandles|feature/"The 'bareword_filehandles' feature."> feature.
778 L<Multidimensional hash lookup is disabled|perldiag/"Multidimensional hash lookup is disabled">
780 This accompanies the new
781 L<multidimensional|feature/"The 'multidimensional' feature"> feature.
791 L<Wide character in setenv key (encoding to utf8)|perldiag/"Wide character in %s">
793 Attempts to put wide characters into environment variable keys via C<%ENV> now
794 provoke this warning.
798 =head2 Changes to Existing Diagnostics
804 L<Error %s in expansion of %s|perldiag/"Error %s in expansion of %s">
806 An error was encountered in handling a user-defined property
807 (L<perlunicode/User-Defined Character Properties>). These are
808 programmer written subroutines, hence subject to errors that may
809 prevent them from compiling or running.
813 L<Infinite recursion in user-defined property|perldiag/"Infinite recursion in user-defined property">
815 A user-defined property (L<perlunicode/User-Defined Character Properties>)
816 can depend on the definitions of other user-defined
817 properties. If the chain of dependencies leads back to this property,
818 infinite recursion would occur, were it not for the check that raised
823 L<Timeout waiting for another thread to define \p{%s}|perldiag/"Timeout waiting for another thread to define \p{%s}">
825 The first time a user-defined property
826 (L<perlunicode/User-Defined Character Properties>) is used, its
827 definition is looked up and converted into an internal form for more
828 efficient handling in subsequent uses. There could be a race if two or
829 more threads tried to do this processing nearly simultaneously.
833 L<Unknown user-defined property name \p{%s}|perldiag/"Unknown user-defined property name \p{%s}">
835 You specified to use a property within the C<\p{...}> which was a
836 syntactically valid user-defined property, but no definition was found
841 L<Too few arguments for subroutine '%s' (got %d; expected %d)|perldiag/"Too few arguments for subroutine '%s' (got %d; expected %d)">
843 Subroutine argument-count mismatch errors now include the number of
844 given and expected arguments.
848 L<Too many arguments for subroutine '%s' (got %d; expected %d)|perldiag/"Too many arguments for subroutine '%s' (got %d; expected %d)">
850 Subroutine argument-count mismatch errors now include the number of
851 given and expected arguments.
855 L<Lost precision when %s %f by 1|perldiag/"Lost precision when %s %f by 1">
857 This warning was only issued for positive too-large values when
858 incrementing, and only for negative ones when decrementing.
859 It is now issued for both positive or negative too-large values.
860 [L<GH #18333|https://github.com/Perl/perl5/issues/18333>]
864 L<\K not permitted in lookahead/lookbehind in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"\K not permitted in lookahead/lookbehind in regex; marked by <-- HERE in m/%s/">
866 This error was incorrectly produced in some cases involving nested
867 lookarounds. This has been fixed.
868 [L<GH #18123|https://github.com/Perl/perl5/issues/18123>]
872 L<Use of uninitialized value%s|perldiag/"Use of uninitialized value%s">
874 This warning may now include the array or hash index when the
875 uninitialized value is the result of an element not found. This will
876 only happen if the index is a simple non-magical variable.
880 =head1 Utility Changes
882 =head2 L<perl5db.pl> (the debugger)
886 =item * New option: C<HistItemMinLength>
888 This option controls the minimum length a command must be to get stored in
889 history. Traditionally, this has been fixed at 2. Changes to the debugger
890 are often perilous, and new bugs should be reported so the debugger can be
893 =item * Fix to C<i> and C<l> commands
895 The C<i $var> and C<l $var> commands work again with lexical variables.
899 =head1 Configuration and Compilation
905 Prevented incpath to spill into libpth
909 Use realpath if available. (This might catch more duplicate paths.)
913 Only include real existing paths.
917 Filter inc paths out of libpth.
919 =item * stadtx hash support has been removed
921 stadtx support has been entirely removed. Previously, it could be requested
922 with C<PERL_HASH_FUNC_STADTX>, and was default in 64-bit builds. It has been
923 replaced with SipHash. SipHash has been more rigorously reviewed than stadtx.
927 A new probe checks for buggy libc implementations of the C<gcvt>/C<qgcvt>
929 [L<GH #18170|https://github.com/Perl/perl5/issues/18170>]
931 =item * C<-Dusedefaultstrict>
933 Perl can now be built with L<strict> on by default (using the configuration
934 option C<-Dusedefaultstrict>.
936 These strict defaults do not apply when C<perl> is run via C<-e> or C<-E>.
938 This setting provides a diagnostic mechanism intended for development
939 purposes only and is thus undefined by default.
943 The minimum supported Bison version is now 2.4, and the maximum is 3.7.
947 Newer 64-bit versions of the Intel C/C++ compiler are now recognised
948 and have the correct flags set.
952 We now trap SIGBUS when F<Configure> checks for C<va_copy>.
954 On several systems the attempt to determine if we need C<va_copy> or similar
955 results in a SIGBUS instead of the expected SIGSEGV, which previously caused a
958 [L<GH #18148|https://github.com/Perl/perl5/issues/18148>]
964 Tests were added and changed to reflect the other additions and
965 changes in this release. Furthermore, these significant changes were
972 Split Config-dependent tests in F<t/opbasic/arith.t> to F<t/op/arith2.t>
976 F<t/re/opt.t> was added, providing a test harness for regexp optimization.
977 [L<GH #18213|https://github.com/Perl/perl5/pull/18213>]
981 A workaround for CPAN distributions needing dot in C<@INC> has been removed
982 [L<GH #18394|https://github.com/Perl/perl5/pull/18394>].
983 All distributions that previously required the workaround have now been
988 When testing in parallel on many-core platforms, you can now cause the
989 test suite to finish somewhat earlier, but with less logical ordering of
990 the tests, by setting
992 PERL_TEST_HARNESS_ASAP=1
994 while running the test suite.
998 =head1 Platform Support
1000 =head2 New Platforms
1006 Allow building Perl on i386 9front systems (a fork of plan9).
1010 =head2 Updated Platforms
1016 Improve support for Plan9 on i386 platforms.
1018 =item MacOS (Darwin)
1020 The hints file for darwin has been updated to handle future MacOS versions
1021 beyond 10. [L<GH #17946|https://github.com/Perl/perl5/issues/17946>]
1025 =head2 Discontinued Platforms
1031 Support code relating to Symbian has been removed. Symbian was an
1032 operating system for mobile devices. The port was last updated in July
1033 2009, and the platform itself in October 2012.
1037 =head2 Platform-Specific Notes
1043 Tests were updated to workaround DragonFlyBSD bugs in L<tc*()
1044 functions|https://bugs.dragonflybsd.org/issues/3252> and L<ctime
1045 updates|https://bugs.dragonflybsd.org/issues/3251>.
1049 A number of system libraries no longer exist as actual files on Big Sur,
1050 even though C<dlopen> will pretend they do, so now we fall back to C<dlopen>
1051 if a library file can not be found.
1052 [L<GH #18407|https://github.com/Perl/perl5/issues/18407>]
1056 Reading non-ASCII characters from the console when its codepage was set to
1057 65001 (UTF-8) was broken due to a bug in Windows. A workaround for this
1058 problem has been implemented.
1059 [L<GH #18701|https://github.com/Perl/perl5/issues/18701>]
1061 Building with mingw.org compilers (version 3.4.5 or later) using mingw runtime
1062 versions < 3.22 now works again. This was broken in Perl 5.31.4.
1064 Building with mingw.org compilers (version 3.4.5 or later) using mingw runtime
1065 versions >= 3.21 now works (for compilers up to version 5.3.0).
1067 F<Makefile.mk>, and thus support for dmake, has been removed. It is still
1068 possible to build Perl on Windows using nmake (Makefile) and GNU make
1070 [L<GH #18511|https://github.com/Perl/perl5/pull/18511>]
1072 perl can now be built with C<USE_QUADMATH> on MS Windows using
1073 (32-bit and 64-bit) mingw-w64 ports of gcc.
1074 [L<GH #18465|https://github.com/Perl/perl5/pull/18465>]
1076 The F<pl2bat.pl> utility now needs to C<use ExtUtils::PL2Bat>. This could
1077 cause failures in parallel builds.
1079 Windows now supports L<symlink()|perlfunc/symlink> and
1080 L<readlink()|perlfunc/readlink>, and L<lstat()|perlfunc/lstat> is no
1081 longer an alias for L<stat()|perlfunc/stat>.
1082 [L<GH #18005|https://github.com/Perl/perl5/issues/18005>].
1084 Unlike POSIX systems, creating a symbolic link on Windows requires
1085 either elevated privileges or Windows 10 1703 or later with Developer
1088 stat(), including C<stat FILEHANDLE>, and lstat() now uses our own
1089 implementation that populates the device C<dev> and inode numbers
1090 C<ino> returned rather than always returning zero. The number of
1091 links C<nlink> field is now always populated.
1093 L<< C<${^WIN32_SLOPPY_STAT}> |perlvar/${^WIN32_SLOPPY_STAT} >> previously
1094 controlled whether the C<nlink> field was populated requiring a
1095 separate Windows API call to fetch, since C<nlink> and the other
1096 information required for C<stat()> is now retrieved in a single API call.
1098 The C<-r> and C<-w> operators now return true for the C<STDIN>,
1099 C<STDOUT> and C<STDERR> handles. Unfortunately it still won't return
1100 true for duplicates of those handles.
1101 [L<GH #8502|https://github.com/Perl/perl5/issues/8502>].
1103 The times returned by stat() and lstat() are no longer incorrect
1104 across Daylight Savings Time adjustments.
1105 [L<GH #6080|https://github.com/Perl/perl5/issues/6080>].
1107 C<-x> on a filehandle should now match C<-x> on the corresponding
1108 filename on Vista or later.
1109 [L<GH #4145|https://github.com/Perl/perl5/issues/4145>].
1111 C<-e '"'> no longer incorrectly returns true.
1112 [L<GH #12431|https://github.com/Perl/perl5/issues/12431>].
1114 The same manifest is now used for Visual C++ and gcc builds.
1116 Previously, MSVC builds were using the B</manifestdependency> flag instead of
1117 embedding F<perlexe.manifest>, which caused issues such as C<GetVersionEx()>
1118 returning the wrong version number on Windows 10.
1122 The locale categories C<LC_SYNTAX> and C<LC_TOD> are now recognized.
1123 Perl doesn't do anything with these, except it now allows you to specify
1124 them. They are included in C<LC_ALL>.
1128 =head1 Internal Changes
1134 Corrected handling of double and long double parameters for perl's
1135 implementation of formatted output for C<-Dusequadmath> builds.
1137 This applies to C<PerlIO_printf()>, C<croak()>, C<warn()>, C<sv_catpvf()> and
1140 Previously in C<quadmath> builds, code like:
1142 PerlIO_printf(PerlIO_stderr(), "%g", somedouble);
1146 PerlIO_printf(PerlIO_stderr(), "%Lg", somelongdouble);
1148 would erroneously throw an exception "panic: quadmath invalid format
1149 ...", since the code added for quadmath builds assumed C<NV>s were the
1150 only floating point format passed into these functions.
1152 This code would also process the standard C long double specifier C<L>
1153 as if it expected an C<NV> (C<__float128> for quadmath builds),
1154 resulting in undefined behaviour.
1156 These functions now correctly accept doubles, long doubles and NVs.
1160 Previously the right operand of bitwise shift operators (shift amount)
1161 was implicitly cast from IV to int, but it might lead wrong results
1162 if IV does not fit in int.
1164 And also, shifting INT_MIN bits used to yield the shiftee unchanged
1165 (treated as 0-bit shift instead of negative shift).
1169 A set of C<cop_hints_exists_{pv,pvn,pvs,sv}> functions was added,
1170 to support checking for the existence of keys in the hints hash of a
1171 specific cop without needing to create a mortal copy of said value.
1175 An aid has been added for using the C<DEBUG> macros when debugging XS or
1176 C code. The comments in F<perl.h> describe C<DEBUG_PRE_STMTS> and
1177 C<DEBUG_POST_STMTS>. which you can C<#define> to do things like save and
1178 restore C<errno>, in case the C<DEBUG> calls are interfering with that,
1179 or to display timestamps, or which thread it's coming from, or the
1180 location of the call, or whatever. You can make a quick hack to help
1181 you track something down without having to edit individual C<DEBUG>
1186 Make C<REFCOUNTED_HE_EXISTS> available outside of core
1190 All C<SvTRUE>-ish functions now evaluate their arguments exactly once.
1191 In 5.32, plain L<perlapi/C<SvTRUE>> was changed to do that; now the rest
1196 Unicode is now a first class citizen when considering the pattern /A*B/ where
1197 A and B are arbitrary. The pattern matching code tries to make a tight loop
1198 to match the span of A's. The logic of this was now really updated with
1203 The L<re> module has a new function C<optimization>, which can return a
1204 hashref of optimization data discovered about a compiled regexp.
1208 The C<PERL_GLOBAL_STRUCT> compilation option has been removed, and
1209 with it the need or the C<dVAR> macro. C<dVAR> remains defined as a
1210 no-op outside C<PERL_CORE> for backwards compatiblity with XS modules.
1214 A new savestack type C<SAVEt_HINTS_HH> has been added, which neatens the
1215 previous behaviour of C<SAVEt_HINTS>. On previous versions the types and
1216 values pushed to the save stack would depend on whether the hints included the
1217 C<HINT_LOCALIZE_HH> bit, which complicates external code that inspects the
1218 save stack. The new version uses a different savestack type to indicate the
1223 A new API function L<perlapi/av_count> has been added which gives a
1224 clearly named way to find how many elements are in an array.
1228 =head1 Selected Bug Fixes
1234 Setting C<%ENV> now properly handles upgraded strings in the key. Previously
1235 Perl sent the SV's internal PV directly to the OS; now it will handle keys
1236 as it has handled values since 5.18: attempt to downgrade the string first;
1237 if that fails then warn and use the utf8 form.
1241 Fix a memory leak in regcomp.c
1242 [L<GH #18604|https://github.com/Perl/perl5/issues/18604>]
1244 =item * pack/unpack format 'D' now works on all systems that could support it
1246 Previously if C<NV == long double>, now it is supported on all platforms that
1247 have long doubles. In particular that means it is now also supported on
1252 Skip trying to constant fold an incomplete op tree
1253 [L<GH #18380|https://github.com/Perl/perl5/issues/18380>]
1255 Constant folding of chained comparison op trees could fail under certain
1256 conditions, causing perl to crash. As a quick fix, constant folding is
1257 now skipped for such op trees. This also addresses
1258 [L<GH #17917|https://github.com/Perl/perl5/issues/17917>].
1262 C<%g> formatting broken on Ubuntu-18.04, C<NVSIZE == 8>
1263 [L<GH #18170|https://github.com/Perl/perl5/issues/18170>]
1265 Buggy libc implementations of the C<gcvt> and C<qgcvt> functions
1266 caused C<(s)printf> to incorrectly truncate C<%g> formatted numbers.
1267 A new Configure probe now checks for this, with the result that the libc
1268 C<sprintf> will be used in place of C<gcvt> and C<qgcvt>.
1270 Tests added as part of this fix also revealed related problems in
1271 some Windows builds. The makefiles for MINGW builds on Windows have
1272 thus been adjusted to use C<USE_MINGW_ANSI_STDIO> by default, ensuring
1273 that they also provide correct C<(s)printf> formatting of numbers.
1277 F<op.c>: croak on C<my $_> when C<use utf8> is in effect
1278 [L<GH #18449|https://github.com/Perl/perl5/issues/18449>]
1280 The lexical topic feature experiment was removed in Perl v5.24 and
1281 declaring C<my $_> became a compile time error. However, it was previously
1282 still possible to make this declaration if C<use utf8> was in effect.
1286 F<regexec.c>: Fix assertion failure
1287 [L<GH #18451|https://github.com/Perl/perl5/issues/18451>]
1289 Fuzzing triggered an assertion failure in the regexp engine when too many
1290 characters were copied into a buffer.
1294 L<semctl()|perlfunc/semctl>, L<msgctl()|perlfunc/msgctl>, and
1295 L<shmctl()|perlfunc/shmctl> now properly reset the UTF-8 flag on the
1296 C<ARG> parameter if it's modified for C<IPC_STAT> or C<GETALL>
1301 C<semctl()>, C<msgctl()>, and C<shmctl()> now attempt to downgrade the C<ARG>
1302 parameter if its value is being used as input to C<IPC_SET> or
1303 C<SETALL> calls. A failed downgrade will thrown an exception.
1307 In cases where C<semctl()>, C<msgctl()> or C<shmctl()> would treat the C<ARG>
1308 parameter as a pointer, an undefined value no longer generates a
1309 warning. In most such calls the pointer isn't used anyway and this
1310 allows you to supply C<undef> for a value not used by the underlying
1315 L<semop()|perlfunc/semop> now downgrades the C<OPSTRING> parameter,
1316 L<msgsnd()|perlfunc/msgsnd> now downgrades the C<MSG> parameter and
1317 L<shmwrite|perlfunc/shmwrite> now downgrades the C<STRING> parameter
1318 to treat them as bytes. Previously they would be left upgraded,
1319 providing a corrupted structure to the underlying function call.
1323 L<msgrcv()|perlfunc/msgrcv> now properly resets the UTF-8 flag the
1324 C<VAR> parameter when it is modified. Previously the UTF-8 flag could
1325 be left on, resulting in a possibly corrupt result in C<VAR>.
1329 Magic is now called correctly for stacked file test operators.
1330 [L<GH #18293|https://github.com/Perl/perl5/issues/18293>]
1334 The C<@ary = split(...)> optimization no longer switches in the target
1335 array as the value stack.
1336 [L<GH #18232|https://github.com/Perl/perl5/issues/18232>]
1337 Also see discussion at
1338 L<https://github.com/Perl/perl5/pull/18014#issuecomment-671299506>.
1342 Fixed a bug in which some regexps with recursive subpatterns matched
1345 [L<GH #18096|https://github.com/Perl/perl5/issues/18096>]
1349 On Win32, C<waitpid(-1, WNOHANG)> could sometimes have a very large
1350 timeout. [L<GH #16529|https://github.com/Perl/perl5/issues/16529>]
1354 C<MARK> and hence C<items> are now correctly initialized in C<BOOT> XSUBs.
1358 Some list assignments involving C<undef> on the left-hand side were
1359 over-optimized and produced incorrect results.
1360 [L<GH #16685|https://github.com/Perl/perl5/issues/16685>],
1361 [L<GH #17816|https://github.com/Perl/perl5/issues/17816>]
1365 =head1 Known Problems
1369 =head1 Errata From Previous Releases
1375 Kent Fredric (KENTNL) passed away in February 2021. A native of New Zealand
1376 and a self-described "huge geek," Kent was the author or maintainer of 178
1377 CPAN distributions, the Perl maintainer for the Gentoo Linux distribution and
1378 a contributor to the Perl core distribution. He is mourned by his family,
1379 friends and open source software communities worldwide.
1381 =head1 Acknowledgements
1383 Perl 5.34.0 represents approximately 11 months of development since Perl
1384 5.32.0 and contains approximately 280,000 lines of changes across 2,100
1385 files from 78 authors.
1387 Excluding auto-generated files, documentation and release tools, there were
1388 approximately 150,000 lines of changes to 1,300 .pm, .t, .c and .h files.
1390 Perl continues to flourish into its fourth decade thanks to a vibrant
1391 community of users and developers. The following people are known to have
1392 contributed the improvements that became Perl 5.34.0:
1394 Aaron Crane, Adam Hartley, Andy Dougherty, Ben Cornett, Branislav
1395 Zahradník, brian d foy, Chris 'BinGOs' Williams, Christian Walde
1396 (Mithaldu), Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Book, Daniel
1397 Böhmer, Daniel Laügt, Dan Kogai, David Cantrell, David Mitchell, Dominic
1398 Hamon, E. Choroba, Ed J, Eric Herman, Eric Lindblad, Eugene Alvin Villar,
1399 Felipe Gasper, Giovanni Tataranni, Graham Knop, Graham Ollis, Hauke D,
1400 H.Merijn Brand, Hugo van der Sanden, Ichinose Shogo, Ivan Baidakou, Jae
1401 Bradley, James E Keenan, Jason McIntosh, jkahrman, John Karr, John Lightsey,
1402 Kang-min Liu, Karen Etheridge, Karl Williamson, Keith Thompson, Leon
1403 Timmermans, Marc Reisner, Marcus Holland-Moritz, Max Maischein, Michael G
1404 Schwern, Nicholas Clark, Nicolas R., Paul Evans, Petr Písař, raiph, Renee
1405 Baecker, Ricardo Signes, Richard Leach, Romano, Ryan Voots, Samanta Navarro,
1406 Samuel Thibault, Sawyer X, Scott Baker, Sergey Poznyakoff, Sevan Janiyan,
1407 Shirakata Kentaro, Shlomi Fish, Sisyphus, Sizhe Zhao, Steve Hay, TAKAI
1408 Kousuke, Thibault Duponchelle, Todd Rinaldo, Tomasz Konojacki, Tom Hukins,
1409 Tom Stellard, Tony Cook, vividsnow, Yves Orton, Zakariyya Mughal,
1412 The list above is almost certainly incomplete as it is automatically
1413 generated from version control history. In particular, it does not include
1414 the names of the (very much appreciated) contributors who reported issues to
1415 the Perl bug tracker.
1417 Many of the changes included in this version originated in the CPAN modules
1418 included in Perl's core. We're grateful to the entire CPAN community for
1419 helping Perl to flourish.
1421 For a more complete list of all of Perl's historical contributors, please
1422 see the F<AUTHORS> file in the Perl source distribution.
1424 =head1 Reporting Bugs
1426 If you find what you think is a bug, you might check the perl bug database
1427 at L<https://github.com/Perl/perl5/issues>. There may also be information at
1428 L<http://www.perl.org/>, the Perl Home Page.
1430 If you believe you have an unreported bug, please open an issue at
1431 L<https://github.com/Perl/perl5/issues>. Be sure to trim your bug down to a
1432 tiny but sufficient test case.
1434 If the bug you are reporting has security implications which make it
1435 inappropriate to send to a public issue tracker, then see
1436 L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
1437 for details of how to report the issue.
1441 If you wish to thank the Perl 5 Porters for the work we had done in Perl 5,
1442 you can do so by running the C<perlthanks> program:
1446 This will send an email to the Perl 5 Porters list with your show of thanks.
1450 The F<Changes> file for an explanation of how to view exhaustive details on
1453 The F<INSTALL> file for how to build Perl.
1455 The F<README> file for general stuff.
1457 The F<Artistic> and F<Copying> files for copyright information.