3 perl571delta - 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 the native dlopen interface of AIX,
42 (given the AIX is recent enough) instead of the old emulated interface.
43 This will probably break backward compatibility with compiled modules.
45 =head2 Socket Extension Dynamic in VMS
47 The Socket extension is now dynamically loaded instead of being
48 statically built in. This may or may not be a problem with ancient
49 TCP/IP stacks of VMS: we do not know since we weren't able to test
50 Perl in such configurations.
54 The current user-visible implementation of pseudo-hashes (the weird
55 use of the first array element) is deprecated starting from Perl 5.8.0
56 and will be removed in Perl 5.10.0, and the feature will be
57 implemented differently. Not only is the current interface rather
58 ugly, but the current implementation slows down normal array and hash
59 use quite noticeably. The 'fields' pragma interface will remain
62 The syntaxes C<@a->[...]> and C<@h->{...}> have now been deprecated.
64 The suidperl is also considered to be too much a risk to continue
65 maintaining and the suidperl code is likely to be removed in a future
68 =head1 Core Enhancements
70 In general a lot of fixing has happened in the area of Perl's
71 understanding of numbers, both integer and floating point. Since in
72 many systems the standard number parsing functions like C<strtoul()>
73 and C<atof()> seem to have bugs, Perl tries to work around their
74 deficiencies. This results hopefully in more accurate numbers.
80 The rules for allowing underscores (underbars) in numeric constants
81 have been relaxed and simplified: now you can have an underscore
86 GMAGIC (right-hand side magic) could in many cases such as string
87 concatenation be invoked too many times.
91 Lexicals I: lexicals outside an eval "" weren't resolved
92 correctly inside a subroutine definition inside the eval "" if they
93 were not already referenced in the top level of the eval""ed code.
97 Lexicals II: lexicals leaked at file scope into subroutines that
98 were declared before the lexicals.
102 Lvalue subroutines can now return C<undef> in list context.
106 The C<op_clear> and C<op_null> are now exported.
110 A new special regular expression variable has been introduced:
111 C<$^N>, which contains the most-recently closed group (submatch).
115 L<utime> now supports C<utime undef, undef, @files> to change the
116 file timestamps to the current time.
120 The Perl parser has been stress tested using both random input and
125 C<eval "v200"> now works.
129 VMS now works under PerlIO.
133 =head1 Modules and Pragmata
135 =head2 New Modules and Distribution
141 L<Attribute::Handlers> - Simpler definition of attribute handlers
145 L<ExtUtils::Constant> - generate XS code to import C header constants
149 L<I18N::LangTags> - functions for dealing with RFC3066-style language tags
153 L<libnet> - a collection of perl5 modules related to network programming
155 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
159 L<List::Util> - selection of general-utility list subroutines
163 L<Locale::Maketext> - framework for localization
167 L<Memoize> - Make your functions faster by trading space for time
171 L<NEXT> - pseudo-class for method redispatch
175 L<Scalar::Util> - selection of general-utility scalar subroutines
179 L<Test::More> - yet another framework for writing test scripts
183 L<Test::Simple> - Basic utilities for writing tests
187 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
191 L<Time::Piece> - Object Oriented time objects
193 (Previously known as L<Time::Object>.)
197 =head2 Updated And Improved Modules and Pragmata
203 L<B::Deparse> module has been significantly enhanced. It now
204 can deparse almost all of the standard test suite (so that the
205 tests still succeed). There is a make target "test.deparse"
210 L<Class::Struct> now assigns the array/hash element if the accessor
211 is called with an array/hash element as the B<sole> argument.
215 L<Cwd> extension is now (even) faster.
219 L<DB_File> extension has been updated to version 1.77.
223 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
224 new-style constant dispatch section (see L<ExtUtils::Constant>).
228 L<File::Find> is now (again) reentrant. It also has been made
233 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
234 size of the returned list of filenames.
238 L<IO::Socket::INET> now supports C<LocalPort> of zero (usually meaning
239 that the operating system will make one up.)
243 The L<vars> pragma now supports declaring fully qualified variables.
244 (Something that C<our()> does not and will not support.)
248 =head1 Utility Changes
254 The F<emacs/e2ctags.pl> is now much faster.
258 L<h2ph> now supports C trigraphs.
262 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
263 newly created extensions that define constants. Since the new code is
264 more correct (if you have two constants where the first one is a
265 prefix of the second one, the first constant B<never> gets defined),
266 less lossy (it uses integers for integer constant, as opposed to the
267 old code that used floating point numbers even for integer constants),
268 and slightly faster, you might want to consider regenerating your
269 extension code (the new scheme makes regenerating easy).
273 L<libnetcfg> has been added to configure the libnet.
277 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
282 =head1 New Documentation
288 L<Locale::Maketext::TPJ13> is an article about software localization,
289 originally published in The Perl Journal #13, republished here with
294 More README.$PLATFORM files have been converted into pod, which also
295 means that they also be installed as perl$PLATFORM documentation
296 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
297 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
302 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
306 Use of the F<gprof> tool to profile Perl has been documented in
307 L<perlhack>. There is a make target "perl.gprof" for generating a
308 gprofiled Perl executable.
312 =head1 Installation and Configuration Improvements
314 =head2 New Or Improved Platforms
320 AIX should now work better with gcc. Also longdouble support in AIX
321 should be better now. See L<perlaix>.
325 AtheOS (http://www.atheos.cx/) is a new platform.
329 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
333 Several MacOS (Classic) portability patches have been applied. We
334 hope to get a fully working port by 5.8.0. (The remaining problems
335 relate to the changed IO model of Perl.) See L<perlmacos>.
339 MacOS X (or Darwin) should now be able to build Perl even on HFS+
340 filesystems. (The case-insensitivity confused the Perl build process.)
344 NetWare from Novell is now supported. See L<perlnetware>.
348 The Amdahl UTS UNIX mainframe platform is now supported.
352 =head2 Generic Improvements
358 In AFS installations one can configure the root of the AFS to be
359 somewhere else than the default F</afs> by using the Configure
360 parameter C<-Dafsroot=/some/where/else>.
364 The version of Berkeley DB used when the Perl (and, presumably, the
365 DB_File extension) was built is now available as
366 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
367 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
368 DB_VERSION_PATCH_CFG> from C.
372 The Thread extension is now not built at all under ithreads
373 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
374 Thread extension requires being Configured with C<-Duse5005threads>).
378 The C<B::Deparse> compiler backend has been so significantly improved
379 that almost the whole Perl test suite passes after being deparsed. A
380 make target has been added to help in further testing: C<make test.deparse>.
384 =head1 Selected Bug Fixes
390 The autouse pragma didn't work for Multi::Part::Function::Names.
394 The behaviour of non-decimal but numeric string constants such as
395 "0x23" was platform-dependent: in some platforms that was seen as 35,
396 in some as 0, in some as a floating point number (don't ask). This
397 was caused by Perl using the operating system libraries in a situation
398 where the result of the string to number conversion is undefined: now
399 Perl consistently handles such strings as zero in numeric contexts.
403 L<dprofpp> -R didn't work.
407 PERL5OPT with embedded spaces didn't work.
411 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
415 =head2 Platform Specific Changes and Fixes
421 Some versions of glibc have a broken modfl(). This affects builds
422 with C<-Duselongdouble>. This version of Perl detects this brokenness
423 and has a workaround for it. The glibc release 2.2.2 is known to have
424 fixed the modfl() bug.
428 =head1 New or Changed Diagnostics
434 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
435 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
436 many people found the C<E<lt>E<lt>> to be too similar to here-document
441 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
442 using the C<"C"> format you will get an optional warning. Similarly
443 for the C<"c"> format and a number less than -128 or more than 127.
447 Certain regex modifiers such as C<(?o)> make sense only if applied to
448 the entire regex. You will an optional warning if you try to do otherwise.
452 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
453 deprecated for a while. Now you will get an optional warning.
457 =head1 Source Code Enhancements
459 =head2 MAGIC constants
461 The MAGIC constants (e.g. C<'P'>) have been macrofied
462 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
465 =head2 Better commented code
467 F<perly.c>, F<sv.c>, and F<sv.h> have now been extensively commented.
469 =head2 Regex pre-/post-compilation items matched up
471 The regex compiler now maintains a structure that identifies nodes in
472 the compiled bytecode with the corresponding syntactic features of the
473 original regex expression. The information is attached to the new
474 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
475 complete information.
479 The C code has been made much more C<gcc -Wall> clean. Some warning
480 messages still remain, though, so if you are compiling with gcc you
481 will see some warnings about dubious practices. The warnings are
486 Several new tests have been added, especially for the F<lib> subsection.
488 The tests are now reported in a different order than in earlier Perls.
489 (This happens because the test scripts from under t/lib have been moved
490 to be closer to the library/extension they are testing.)
492 =head1 Known Problems
494 Note that unlike other sections in this document (which describe
495 changes since 5.7.0) this section is cumulative containing known
496 problems for all the 5.7 releases.
504 If Perl is configured to use long doubles the op/int subtests 13 and
505 14 and the ext/POSIX subtest 14 may fail.
509 If Perl is configured to use threads the op/magic subtest 28 may fail.
513 vac 5.0.0.0 May Produce Buggy Code For Perl
515 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
516 resulting in few random tests failing, but when the failing tests
517 are run by hand, they succeed. We suggest upgrading to at least
518 vac version 5.0.1.0, that has been known to compile Perl correctly.
519 "lslpp -L|grep vac.C" will tell you the vac version.
523 =head2 Amiga Perl Invoking Mystery
525 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
526 works, but for example C<bin:perl -v> doesn't. The exact reason is
527 known but the current suspect is the F<ixemul> library.
529 =head2 lib/ftmp-security tests warn 'system possibly insecure'
531 Don't panic. Read INSTALL 'make test' section instead.
533 =head2 Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
535 The subtests 11 and 12 sometimes fail and sometimes work.
537 =head2 HP-UX lib/io_multihomed Fails When LP64-Configur
539 The lib/io_multihomed test may hang in HP-UX if Perl has been
540 configured to be 64-bit. Because other 64-bit platforms do not hang in
541 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
542 test attempts to create and connect to "multihomed" sockets (sockets
543 which have multiple IP addresses).
545 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
547 If perl is configured with -Duse64bitall, the successful result of the
548 subtest 10 of lib/posix may arrive before the successful result of the
549 subtest 9, which confuses the test harness so much that it thinks the
552 =head2 Linux With Sfio Fails op/misc Test 48
556 =head2 op/sprintf tests 129 and 130
558 The op/sprintf tests 129 and 130 are known to fail on some platforms.
559 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
560 The failing platforms do not comply with the ANSI C Standard, line
561 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
562 something else than "1" and "-1" when formatting 0.6 and -0.6 using
563 the printf format "%.0f", most often they produce "0" and "-0".)
565 =head2 Failure of Thread tests
567 B<Note that support for 5.005-style threading remains experimental.>
569 The following tests are known to fail due to fundamental problems in
570 the 5.005 threading implementation. These are not new failures--Perl
571 5.005_0x has the same bugs, but didn't have these tests.
574 t/lib/thr5005.t 19-20
582 ext/POSIX/sigaction subtests 6 and 13 may fail.
586 lib/ExtUtils may spuriously claim that subtest 28 failed,
587 which is interesting since the test only has 27 tests.
591 Numerous numerical test failures
593 op/numconvert 209,210,217,218
595 ext/Time/HiRes/HiRes 9
596 lib/Math/BigInt/t/bigintpm 1145
599 These tests fail because of yet unresolved floating point inaccuracies.
603 =head2 UNICOS/mk ext/IPC/SysV/t/sem test 8
609 Many floating point inaccuracies:
611 op/numconvert 511,657,658,659,665-667,831,991,1151
612 op/pack 10,22,149,156
613 op/sprintf 8,10,13,102-107,134-135,146-153,159-162
614 lib/Math/BigInt/bigintpm 1145,1183
615 lib/Math/Complex 250,257,514,521,722-724,
616 934,935,945,949,955,956,975,976
621 DEC C V5.3-006 on OpenVMS VAX V6.2
623 [-.ext.list.util.t]tainted..............FAILED on test 3
624 [-.ext.posix]sigaction..................FAILED on test 7
625 [-.ext.time.hires]hires.................FAILED on test 14
626 [-.lib.file.find]taint..................FAILED on test 17
627 [-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
628 [-.lib.test.simple.t]exit...............FAILED on test 1
629 [.lib]vmsish............................FAILED on test 13
630 [.op]sprintf............................FAILED on test 12
631 Failed 8/399 tests, 91.23% okay.
633 DEC C V6.0-001 on OpenVMS Alpha V7.2-1
635 [-.ext.list.util.t]tainted..............FAILED on test 3
636 [-.lib.file.find]taint..................FAILED on test 17
637 [-.lib.test.simple.t]exit...............FAILED on test 1
638 [.lib]vmsish............................FAILED on test 13
639 Failed 4/399 tests, 92.48% okay.
641 Compac C V6.4-005 on OpenVMS Alpha 7.2.1
643 [-.ext.b]showlex........................FAILED on test 1
644 [-.ext.list.util.t]tainted..............FAILED on test 3
645 [-.lib.file.find]taint..................FAILED on test 17
646 [-.lib.test.simple.t]exit...............FAILED on test 1
647 [.lib]vmsish............................FAILED on test 13
648 [.op]misc...............................FAILED on test 49
649 Failed 6/401 tests, 92.77% okay.
651 =head2 Localising a Tied Variable Leaks Memory
654 tie my %tie_hash => 'Tie::StdHash';
658 local($tie_hash{Foo}) = 1; # leaks
660 Code like the above is known to leak memory every time the local()
663 =head2 Self-tying of Arrays and Hashes Is Forbidden
665 Self-tying of arrays and hashes is broken in rather deep and
666 hard-to-fix ways. As a stop-gap measure to avoid people from getting
667 frustrated at the mysterious results (core dumps, most often) it is
668 for now forbidden (you will get a fatal error even from an attempt).
670 =head2 Variable Attributes are not Currently Usable for Tieing
672 This limitation will hopefully be fixed in future. (Subroutine
673 attributes work fine for tieing, see L<Attribute::Handlers>).
675 =head2 Building Extensions Can Fail Because Of Largefiles
677 Some extensions like mod_perl are known to have issues with
678 `largefiles', a change brought by Perl 5.6.0 in which file offsets
679 default to 64 bits wide, where supported. Modules may fail to compile
680 at all or compile and work incorrectly. Currently there is no good
681 solution for the problem, but Configure now provides appropriate
682 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
683 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
684 having problems can try configuring themselves without the
685 largefileness. This is admittedly not a clean solution, and the
686 solution may not even work at all. One potential failure is whether
687 one can (or, if one can, whether it's a good idea) link together at
688 all binaries with different ideas about file offsets, all this is
691 =head2 The Compiler Suite Is Still Experimental
693 The compiler suite is slowly getting better but is nowhere near
696 =head2 The Long Double Support is Still Experimental
698 The ability to configure Perl's numbers to use "long doubles",
699 floating point numbers of hopefully better accuracy, is still
700 experimental. The implementations of long doubles are not yet
701 widespread and the existing implementations are not quite mature
702 or standardised, therefore trying to support them is a rare
703 and moving target. The gain of more precision may also be offset
704 by slowdown in computations (more bits to move around, and the
705 operations are more likely to be executed by less optimised
708 =head1 Reporting Bugs
710 If you find what you think is a bug, you might check the articles
711 recently posted to the comp.lang.perl.misc newsgroup and the perl
712 bug database at http://bugs.perl.org. There may also be
713 information at http://www.perl.com/perl/, the Perl Home Page.
715 If you believe you have an unreported bug, please run the B<perlbug>
716 program included with your release. Be sure to trim your bug down
717 to a tiny but sufficient test case. Your bug report, along with the
718 output of C<perl -V>, will be sent off to perlbug@perl.org to be
719 analysed by the Perl porting team.
723 The F<Changes> file for exhaustive details on what changed.
725 The F<INSTALL> file for how to build Perl.
727 The F<README> file for general stuff.
729 The F<Artistic> and F<Copying> files for copyright information.
733 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
734 from The Perl Porters and Perl Users submitting feedback and patches.
736 Send omissions or corrections to <F<perlbug@perl.org>>.