3 perl572delta - what's new for perl v5.7.2
7 This document describes differences between the 5.7.1 release and the
10 (To view the differences between the 5.6.0 release and the 5.7.0
11 release, see L<perl570delta>. To view the differences between the
12 5.7.0 release and the 5.7.1 release, see L<perl571delta>.)
14 =head1 Security Vulnerability Closed
16 (This change was already made in 5.7.0 but bears repeating here.)
18 A security vulnerability affecting all Perl versions prior to 5.6.1
19 was found in August 2000. The vulnerability does not affect default
20 installations and as far as is known affects only the Linux platform.
22 You should upgrade your Perl to 5.6.1 as soon as possible. Patches
23 for earlier releases exist but using the patches require full
24 recompilation from the source code anyway, so 5.6.1 is your best
27 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
30 =head1 Incompatible Changes
32 =head2 64-bit platforms and malloc
34 If your pointers are 64 bits wide, the Perl malloc is no more being
35 used because it simply does not work with 8-byte pointers. Also,
36 usually the system malloc on such platforms are much better optimized
37 for such large memory models than the Perl malloc.
39 =head2 AIX Dynaloading
41 The AIX dynaloading now uses in AIX releases 4.3 and newer the native
42 dlopen interface of AIX instead of the old emulated interface. This
43 change will probably break backward compatibility with compiled
44 modules. The change was made to make Perl more compliant with other
45 applications like modperl which are using the AIX native interface.
47 =head2 Socket Extension Dynamic in VMS
49 The Socket extension is now dynamically loaded instead of being
50 statically built in. This may or may not be a problem with ancient
51 TCP/IP stacks of VMS: we do not know since we weren't able to test
52 Perl in such configurations.
54 =head2 Different Definition of the Unicode Character Classes \p{In...}
56 As suggested by the Unicode consortium, the Unicode character classes
57 now prefer I<scripts> as opposed to I<blocks> (as defined by Unicode);
58 in Perl, when the C<\p{In....}> and the C<\p{In....}> regular expression
59 constructs are used. This has changed the definition of some of those
62 The difference between scripts and blocks is that scripts are the
63 glyphs used by a language or a group of languages, while the blocks
64 are more artificial groupings of 256 characters based on the Unicode
67 In general this change results in more inclusive Unicode character
68 classes, but changes to the other direction also do take place:
69 for example while the script C<Latin> includes all the Latin
70 characters and their various diacritic-adorned versions, it
71 does not include the various punctuation or digits (since they
72 are not solely C<Latin>).
74 Changes in the character class semantics may have happened if a script
75 and a block happen to have the same name, for example C<Hebrew>.
76 In such cases the script wins and C<\p{InHebrew}> now means the script
77 definition of Hebrew. The block definition in still available,
78 though, by appending C<Block> to the name: C<\p{InHebrewBlock}> means
79 what C<\p{InHebrew}> meant in perl 5.6.0. For the full list
80 of affected character classes, see L<perlunicode/Blocks>.
84 The current user-visible implementation of pseudo-hashes (the weird
85 use of the first array element) is deprecated starting from Perl 5.8.0
86 and will be removed in Perl 5.10.0, and the feature will be
87 implemented differently. Not only is the current interface rather
88 ugly, but the current implementation slows down normal array and hash
89 use quite noticeably. The C<fields> pragma interface will remain
92 The syntaxes C<@a->[...]> and C<@h->{...}> have now been deprecated.
94 The suidperl is also considered to be too much a risk to continue
95 maintaining and the suidperl code is likely to be removed in a future
98 The C<package;> syntax (C<package> without an argument has been
99 deprecated. Its semantics were never that clear and its
100 implementation even less so. If you have used that feature to
101 disallow all but fully qualified variables, C<use strict;> instead.
103 =head1 Core Enhancements
105 In general a lot of fixing has happened in the area of Perl's
106 understanding of numbers, both integer and floating point. Since in
107 many systems the standard number parsing functions like C<strtoul()>
108 and C<atof()> seem to have bugs, Perl tries to work around their
109 deficiencies. This results hopefully in more accurate numbers.
115 The rules for allowing underscores (underbars) in numeric constants
116 have been relaxed and simplified: now you can have an underscore
121 GMAGIC (right-hand side magic) could in many cases such as string
122 concatenation be invoked too many times.
126 Lexicals I: lexicals outside an eval "" weren't resolved
127 correctly inside a subroutine definition inside the eval "" if they
128 were not already referenced in the top level of the eval""ed code.
132 Lexicals II: lexicals leaked at file scope into subroutines that
133 were declared before the lexicals.
137 Lvalue subroutines can now return C<undef> in list context.
141 The C<op_clear> and C<op_null> are now exported.
145 A new special regular expression variable has been introduced:
146 C<$^N>, which contains the most-recently closed group (submatch).
150 L<utime> now supports C<utime undef, undef, @files> to change the
151 file timestamps to the current time.
155 The Perl parser has been stress tested using both random input and
160 C<eval "v200"> now works.
164 VMS now works under PerlIO.
168 END blocks are now run even if you exit/die in a BEGIN block.
169 The execution of END blocks is now controlled by
170 PL_exit_flags & PERL_EXIT_DESTRUCT_END. This enables the new
171 behaviour for perl embedders. This will default in 5.10. See
176 =head1 Modules and Pragmata
178 =head2 New Modules and Distributions
184 L<Attribute::Handlers> - Simpler definition of attribute handlers
188 L<ExtUtils::Constant> - generate XS code to import C header constants
192 L<I18N::Langinfo> - query locale information
196 L<I18N::LangTags> - functions for dealing with RFC3066-style language tags
200 L<libnet> - a collection of perl5 modules related to network programming
202 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
206 L<List::Util> - selection of general-utility list subroutines
210 L<Locale::Maketext> - framework for localization
214 L<Memoize> - Make your functions faster by trading space for time
218 L<NEXT> - pseudo-class for method redispatch
222 L<Scalar::Util> - selection of general-utility scalar subroutines
226 L<Test::More> - yet another framework for writing test scripts
230 L<Test::Simple> - Basic utilities for writing tests
234 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
238 L<Time::Piece> - Object Oriented time objects
240 (Previously known as L<Time::Object>.)
244 L<Time::Seconds> - a simple API to convert seconds to other date values
248 L<UnicodeCD> - Unicode Character Database
252 =head2 Updated And Improved Modules and Pragmata
258 L<B::Deparse> module has been significantly enhanced. It now
259 can deparse almost all of the standard test suite (so that the
260 tests still succeed). There is a make target "test.deparse"
265 L<Class::Struct> now assigns the array/hash element if the accessor
266 is called with an array/hash element as the B<sole> argument.
270 L<Cwd> extension is now (even) faster.
274 L<DB_File> extension has been updated to version 1.77.
278 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
279 new-style constant dispatch section (see L<ExtUtils::Constant>).
283 L<File::Find> is now (again) reentrant. It also has been made
288 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
289 size of the returned list of filenames.
293 L<IO::Socket::INET> now supports C<LocalPort> of zero (usually meaning
294 that the operating system will make one up.)
298 The L<vars> pragma now supports declaring fully qualified variables.
299 (Something that C<our()> does not and will not support.)
303 =head1 Utility Changes
309 The F<emacs/e2ctags.pl> is now much faster.
313 L<h2ph> now supports C trigraphs.
317 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
318 newly created extensions that define constants. Since the new code is
319 more correct (if you have two constants where the first one is a
320 prefix of the second one, the first constant B<never> gets defined),
321 less lossy (it uses integers for integer constant, as opposed to the
322 old code that used floating point numbers even for integer constants),
323 and slightly faster, you might want to consider regenerating your
324 extension code (the new scheme makes regenerating easy).
325 L<h2xs> now also supports C trigraphs.
329 L<libnetcfg> has been added to configure the libnet.
333 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
338 =head1 New Documentation
344 L<Locale::Maketext::TPJ13> is an article about software localization,
345 originally published in The Perl Journal #13, republished here with
350 More README.$PLATFORM files have been converted into pod, which also
351 means that they also be installed as perl$PLATFORM documentation
352 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
353 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
358 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
362 Use of the F<gprof> tool to profile Perl has been documented in
363 L<perlhack>. There is a make target "perl.gprof" for generating a
364 gprofiled Perl executable.
368 =head1 Installation and Configuration Improvements
370 =head2 New Or Improved Platforms
376 AIX should now work better with gcc, threads, and 64-bitness. Also the
377 long doubles support in AIX should be better now. See L<perlaix>.
381 AtheOS (http://www.atheos.cx/) is a new platform.
385 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
389 DYNIX/ptx platform (a.k.a. dynixptx) is supported at or near osvers 4.5.2.
393 Several MacOS (Classic) portability patches have been applied. We
394 hope to get a fully working port by 5.8.0. (The remaining problems
395 relate to the changed IO model of Perl.) See L<perlmacos>.
399 MacOS X (or Darwin) should now be able to build Perl even on HFS+
400 filesystems. (The case-insensitivity confused the Perl build process.)
404 NetWare from Novell is now supported. See L<perlnetware>.
408 The Amdahl UTS UNIX mainframe platform is now supported.
412 =head2 Generic Improvements
418 In AFS installations one can configure the root of the AFS to be
419 somewhere else than the default F</afs> by using the Configure
420 parameter C<-Dafsroot=/some/where/else>.
424 The version of Berkeley DB used when the Perl (and, presumably, the
425 DB_File extension) was built is now available as
426 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
427 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
428 DB_VERSION_PATCH_CFG> from C.
432 The Thread extension is now not built at all under ithreads
433 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
434 Thread extension requires being Configured with C<-Duse5005threads>).
438 The C<B::Deparse> compiler backend has been so significantly improved
439 that almost the whole Perl test suite passes after being deparsed. A
440 make target has been added to help in further testing: C<make test.deparse>.
444 =head1 Selected Bug Fixes
450 The autouse pragma didn't work for Multi::Part::Function::Names.
454 The behaviour of non-decimal but numeric string constants such as
455 "0x23" was platform-dependent: in some platforms that was seen as 35,
456 in some as 0, in some as a floating point number (don't ask). This
457 was caused by Perl using the operating system libraries in a situation
458 where the result of the string to number conversion is undefined: now
459 Perl consistently handles such strings as zero in numeric contexts.
463 L<dprofpp> -R didn't work.
467 PERL5OPT with embedded spaces didn't work.
471 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
475 =head2 Platform Specific Changes and Fixes
481 Some versions of glibc have a broken modfl(). This affects builds
482 with C<-Duselongdouble>. This version of Perl detects this brokenness
483 and has a workaround for it. The glibc release 2.2.2 is known to have
484 fixed the modfl() bug.
488 =head1 New or Changed Diagnostics
494 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
495 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
496 many people found the C<E<lt>E<lt>> to be too similar to here-document
501 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
502 using the C<"C"> format you will get an optional warning. Similarly
503 for the C<"c"> format and a number less than -128 or more than 127.
507 Certain regex modifiers such as C<(?o)> make sense only if applied to
508 the entire regex. You will an optional warning if you try to do otherwise.
512 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
513 deprecated for a while. Now you will get an optional warning.
517 =head1 Source Code Enhancements
519 =head2 MAGIC constants
521 The MAGIC constants (e.g. C<'P'>) have been macrofied
522 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
525 =head2 Better commented code
527 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
529 =head2 Regex pre-/post-compilation items matched up
531 The regex compiler now maintains a structure that identifies nodes in
532 the compiled bytecode with the corresponding syntactic features of the
533 original regex expression. The information is attached to the new
534 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
535 complete information.
539 The C code has been made much more C<gcc -Wall> clean. Some warning
540 messages still remain, though, so if you are compiling with gcc you
541 will see some warnings about dubious practices. The warnings are
546 Several new tests have been added, especially for the F<lib> subsection.
548 The tests are now reported in a different order than in earlier Perls.
549 (This happens because the test scripts from under t/lib have been moved
550 to be closer to the library/extension they are testing.)
552 =head1 Known Problems
554 Note that unlike other sections in this document (which describe
555 changes since 5.7.0) this section is cumulative containing known
556 problems for all the 5.7 releases.
564 In AIX 4.2 Perl extensions that use C++ functions that use statics
565 may have problems in that the statics are not getting initialized.
566 In newer AIX releases this has been solved by linking Perl with
567 the libC_r library, but unfortunately in AIX 4.2 the said library
568 has an obscure bug where the various functions related to time
569 (such as time() and gettimeofday()) return broken values, and
570 therefore in AIX 4.2 Perl is not linked against the libC_r.
574 vac 5.0.0.0 May Produce Buggy Code For Perl
576 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
577 resulting in few random tests failing, but when the failing tests
578 are run by hand, they succeed. We suggest upgrading to at least
579 vac version 5.0.1.0, that has been known to compile Perl correctly.
580 "lslpp -L|grep vac.C" will tell you the vac version.
584 =head2 Amiga Perl Invoking Mystery
586 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
587 works, but for example C<bin:perl -v> doesn't. The exact reason is
588 known but the current suspect is the F<ixemul> library.
590 =head2 lib/ftmp-security tests warn 'system possibly insecure'
592 Don't panic. Read INSTALL 'make test' section instead.
594 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
596 The subtests 11 and 12 sometimes fail and sometimes work.
598 =head2 HP-UX lib/io_multihomed Fails When LP64-Configur
600 The lib/io_multihomed test may hang in HP-UX if Perl has been
601 configured to be 64-bit. Because other 64-bit platforms do not hang in
602 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
603 test attempts to create and connect to "multihomed" sockets (sockets
604 which have multiple IP addresses).
606 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
608 If perl is configured with -Duse64bitall, the successful result of the
609 subtest 10 of lib/posix may arrive before the successful result of the
610 subtest 9, which confuses the test harness so much that it thinks the
613 =head2 Linux With Sfio Fails op/misc Test 48
619 OS/390 has rather many test failures but the situation is actually
620 better than it was in 5.6.0, it's just that so many new modules and
621 tests have been added.
623 Failed Test Stat Wstat Total Fail Failed List of Failed
624 -----------------------------------------------------------------------------
625 ../ext/B/Deparse.t 14 1 7.14% 14
626 ../ext/B/Showlex.t 1 1 100.00% 1
627 ../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
629 ../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
630 ../ext/POSIX/POSIX.t 29 1 3.45% 14
631 ../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
632 ../lib/locale.t 129 33024 117 19 16.24% 99-117
633 ../lib/warnings.t 434 1 0.23% 75
634 ../lib/ExtUtils.t 27 1 3.70% 25
635 ../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
636 ../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
637 ../lib/User/pwent.t 9 1 11.11% 4
638 op/pat.t 660 6 0.91% 242-243 424-425
640 op/split.t 0 9 ?? ?? % ??
641 op/taint.t 174 3 1.72% 156 162 168
642 op/tr.t 70 3 4.29% 50 58-59
643 Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
645 =head2 op/sprintf tests 129 and 130
647 The op/sprintf tests 129 and 130 are known to fail on some platforms.
648 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
649 The failing platforms do not comply with the ANSI C Standard, line
650 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
651 something other than "1" and "-1" when formatting 0.6 and -0.6 using
652 the printf format "%.0f", most often they produce "0" and "-0".)
654 =head2 Failure of Thread tests
656 B<Note that support for 5.005-style threading remains experimental.>
658 The following tests are known to fail due to fundamental problems in
659 the 5.005 threading implementation. These are not new failures--Perl
660 5.005_0x has the same bugs, but didn't have these tests.
663 t/lib/thr5005.t 19-20
671 ext/POSIX/sigaction subtests 6 and 13 may fail.
675 lib/ExtUtils may spuriously claim that subtest 28 failed,
676 which is interesting since the test only has 27 tests.
680 Numerous numerical test failures
682 op/numconvert 209,210,217,218
684 ext/Time/HiRes/HiRes 9
685 lib/Math/BigInt/t/bigintpm 1145
688 These tests fail because of yet unresolved floating point inaccuracies.
694 There are a few known test failures, see L<perluts>.
698 Rather many tests are failing in VMS but that actually more tests
699 succeed in VMS than they used to, it's just that there are many,
700 many more tests than there used to be.
702 Here are the known failures from some compiler/platform combinations.
704 DEC C V5.3-006 on OpenVMS VAX V6.2
706 [-.ext.list.util.t]tainted..............FAILED on test 3
707 [-.ext.posix]sigaction..................FAILED on test 7
708 [-.ext.time.hires]hires.................FAILED on test 14
709 [-.lib.file.find]taint..................FAILED on test 17
710 [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
711 [-.lib.test.simple.t]exit...............FAILED on test 1
712 [.lib]vmsish............................FAILED on test 13
713 [.op]sprintf............................FAILED on test 12
714 Failed 8/399 tests, 91.23% okay.
716 DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and
717 Compaq C V6.2-008 on OpenVMS Alpha V7.1
719 [-.ext.list.util.t]tainted..............FAILED on test 3
720 [-.lib.file.find]taint..................FAILED on test 17
721 [-.lib.test.simple.t]exit...............FAILED on test 1
722 [.lib]vmsish............................FAILED on test 13
723 Failed 4/399 tests, 92.48% okay.
725 Compac C V6.4-005 on OpenVMS Alpha 7.2.1
727 [-.ext.b]showlex........................FAILED on test 1
728 [-.ext.list.util.t]tainted..............FAILED on test 3
729 [-.lib.file.find]taint..................FAILED on test 17
730 [-.lib.test.simple.t]exit...............FAILED on test 1
731 [.lib]vmsish............................FAILED on test 13
732 [.op]misc...............................FAILED on test 49
733 Failed 6/401 tests, 92.77% okay.
737 In multi-CPU boxes there are some problems with the I/O buffering:
738 some output may appear twice.
740 =head2 Localising a Tied Variable Leaks Memory
743 tie my %tie_hash => 'Tie::StdHash';
747 local($tie_hash{Foo}) = 1; # leaks
749 Code like the above is known to leak memory every time the local()
752 =head2 Self-tying of Arrays and Hashes Is Forbidden
754 Self-tying of arrays and hashes is broken in rather deep and
755 hard-to-fix ways. As a stop-gap measure to avoid people from getting
756 frustrated at the mysterious results (core dumps, most often) it is
757 for now forbidden (you will get a fatal error even from an attempt).
759 =head2 Variable Attributes are not Currently Usable for Tieing
761 This limitation will hopefully be fixed in future. (Subroutine
762 attributes work fine for tieing, see L<Attribute::Handlers>).
764 =head2 Building Extensions Can Fail Because Of Largefiles
766 Some extensions like mod_perl are known to have issues with
767 `largefiles', a change brought by Perl 5.6.0 in which file offsets
768 default to 64 bits wide, where supported. Modules may fail to compile
769 at all or compile and work incorrectly. Currently there is no good
770 solution for the problem, but Configure now provides appropriate
771 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
772 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
773 having problems can try configuring themselves without the
774 largefileness. This is admittedly not a clean solution, and the
775 solution may not even work at all. One potential failure is whether
776 one can (or, if one can, whether it's a good idea) link together at
777 all binaries with different ideas about file offsets, all this is
780 =head2 The Compiler Suite Is Still Experimental
782 The compiler suite is slowly getting better but is nowhere near
785 =head2 The Long Double Support is Still Experimental
787 The ability to configure Perl's numbers to use "long doubles",
788 floating point numbers of hopefully better accuracy, is still
789 experimental. The implementations of long doubles are not yet
790 widespread and the existing implementations are not quite mature
791 or standardised, therefore trying to support them is a rare
792 and moving target. The gain of more precision may also be offset
793 by slowdown in computations (more bits to move around, and the
794 operations are more likely to be executed by less optimised
797 =head1 Reporting Bugs
799 If you find what you think is a bug, you might check the articles
800 recently posted to the comp.lang.perl.misc newsgroup and the perl
801 bug database at http://bugs.perl.org. There may also be
802 information at http://www.perl.com/perl/, the Perl Home Page.
804 If you believe you have an unreported bug, please run the B<perlbug>
805 program included with your release. Be sure to trim your bug down
806 to a tiny but sufficient test case. Your bug report, along with the
807 output of C<perl -V>, will be sent off to perlbug@perl.org to be
808 analysed by the Perl porting team.
812 The F<Changes> file for exhaustive details on what changed.
814 The F<INSTALL> file for how to build Perl.
816 The F<README> file for general stuff.
818 The F<Artistic> and F<Copying> files for copyright information.
822 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
823 from The Perl Porters and Perl Users submitting feedback and patches.
825 Send omissions or corrections to <F<perlbug@perl.org>>.