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 concatenation
87 of string 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 MAGIC constants (e.g. C<'P'>) have been macrofied
107 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
112 The C<op_clear> and C<op_null> are now exported.
116 L<utime> now supports C<utime undef, undef, @files> to change the
117 file timestamps to the current time.
121 The Perl parser has been stress tested using both random input and
126 C<eval "v200"> now works.
130 VMS now works under PerlIO.
134 =head1 Modules and Pragmata
136 =head2 New Modules and Distribution
142 L<Attribute::Handlers> - Simpler definition of attribute handlers
146 L<ExtUtils::Constant> - generate XS code to import C header constants
150 L<I18N::LangTags> - functions for dealing with RFC3066-style language tags
154 L<libnet> - a collection of perl5 modules related to network programming
156 Perl installation leaves libnet unconfigured, use F<libnetcfg> to configure.
160 L<List::Util> - selection of general-utility list subroutines
164 L<Locale::Maketext> - framework for localization
168 L<Memoize> - Make your functions faster by trading space for time
172 L<NEXT> - pseudo-class for method redispatch
176 L<Scalar::Util> - selection of general-utility scalar subroutines
180 L<Test::More> - yet another framework for writing test scripts
184 L<Test::Simple> - Basic utilities for writing tests
188 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
192 L<Time::Piece> - Object Oriented time objects
194 (Previously known as L<Time::Object>.)
198 =head2 Updated And Improved Modules and Pragmata
204 L<B::Deparse> module has been significantly enhanced. It now
205 can deparse almost all of the standard test suite (so that the
206 tests still succeed). There is a make target "test.deparse"
211 L<Class::Struct> now assigns the array/hash element if the accessor
212 is called with an array/hash element as the B<sole> argument.
216 L<Cwd> extension is now (even) faster.
220 L<DB_File> extension has been updated to version 1.77.
224 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
225 new-style constant dispatch section (see L<ExtUtils::Constant>).
229 L<File::Find> is now (again) reentrant. It also has been made
234 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
235 size of the returned list of filenames.
239 L<IO::Socket::INET> now supports C<LocalPort> of zero (usually meaning
240 that the operating system will make one up.)
244 The L<vars> pragma now supports declaring fully qualified variables.
245 (Something that C<our()> does not and will not support.)
249 =head1 Utility Changes
255 The F<emacs/e2ctags.pl> is now much faster.
259 L<h2ph> now supports C trigraphs.
263 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
264 newly created extensions that define constants. Since the new code is
265 more correct (if you have two constants where the first one is a
266 prefix of the second one, the first constant B<never> gets defined),
267 less lossy (it uses integers for integer constant, as opposed to the
268 old code that used floating point numbers even for integer constants),
269 and slightly faster, you might want to consider regenerating your
270 extension code (the new scheme makes regenerating easy).
274 L<libnetcfg> has been added to configure the libnet.
278 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
283 =head1 New Documentation
289 L<Locale::Maketext::TPJ13> is an article about software localization,
290 originally published in The Perl Journal #13, republished here with
295 More README.$PLATFORM files have been converted into pod, which also
296 means that they also be installed as perl$PLATFORM documentation
297 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
298 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
303 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
307 Use of the F<gprof> tool to profile Perl has been documented in
308 L<perlhack>. There is a make target "perl.gprof" for generating a
309 gprofiled Perl executable.
313 (Code documentation) F<perly.c> and F<sv.c> have now been extensively
318 =head1 Installation and Configuration Improvements
320 =head2 New Or Improved Platforms
326 AIX should now work better with gcc. Also longdouble support in AIX
327 should be better now. See L<perlaix>.
331 AtheOS (http://www.atheos.cx/) is a new platform.
335 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
339 Several MacOS (Classic) portability patches have been applied. We
340 hope to get a fully working port by 5.8.0. (The remaining problems
341 relate to the changed IO model of Perl.) See L<perlmacos>.
345 MacOS X (or Darwin) should now be able to build Perl even on HFS+
346 filesystems. (The case-insensitivity confused the Perl build process.)
350 NetWare from Novell is now supported. See L<perlnetware>.
354 The Amdahl UTS UNIX mainframe platform is now supported.
358 =head2 Generic Improvements
364 The C code has been made much more C<gcc -Wall> clean. Some warning
365 messages still remain, though, so if you are compiling with gcc you
366 will see some warnings about dubious practices. The warnings are
371 In AFS installations one can configure the root of the AFS to be
372 somewhere else than the default F</afs> by using the Configure
373 parameter C<-Dafsroot=/some/where/else>.
377 The version of Berkeley DB used when the Perl (and, presumably, the
378 DB_File extension) was built is now available as
379 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
380 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
381 DB_VERSION_PATCH_CFG> from C.
385 The Thread extension is now not built at all under ithreads
386 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
387 Thread extension requires being Configured with C<-Duse5005threads>).
391 The C<B::Deparse> compiler backend has been so significantly improved
392 that almost the whole Perl test suite passes after being deparsed. A
393 make target has been added to help in further testing: C<make test.deparse>.
397 =head1 Selected Bug Fixes
403 The autouse pragma didn't work for Multi::Part::Function::Names.
407 The behaviour of non-decimal but numeric string constants such as
408 "0x23" was platform-dependent: in some platforms that was seen as 35,
409 in some as 0, in some as a floating point number (don't ask). This
410 was caused by Perl using the operating system libraries in a situation
411 where the result of the string to number conversion is undefined: now
412 Perl consistently handles such strings as zero in numeric contexts.
416 L<dprofpp> -R didn't work.
420 PERL5OPT with embedded spaces didn't work.
424 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
428 =head2 Platform Specific Changes and Fixes
434 Some versions of glibc have a broken modfl(). This affects builds
435 with C<-Duselongdouble>. This version of Perl detects this brokenness
436 and has a workaround for it. The glibc release 2.2.2 is known to have
437 fixed the modfl() bug.
441 =head1 New or Changed Diagnostics
447 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
448 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
449 many people found the C<E<lt>E<lt>> to be too similar to here-document
454 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
455 using the C<"C"> format you will get an optional warning. Similarly
456 for the C<"c"> format and a number less than -128 or more than 127.
460 Certain regex modifiers such as C<(?o)> make sense only if applied to
461 the entire regex. You will an optional warning if you try to do otherwise.
465 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
466 deprecated for a while. Now you will get an optional warning.
470 =head1 Changed Internals
472 =head2 Regex pre-/post-compilation items matched up
474 The regex compiler now maintains a structure that identifies nodes in
475 the compiled bytecode with the corresponding syntactic features of the
476 original regex expression. The information is attached to the new
477 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
478 complete information.
482 Several new tests have been added, especially for the F<lib> subsection.
484 The tests are now reported in a different order than in earlier Perls.
485 (This happens because the test scripts from under t/lib have been moved
486 to be closer to the library/extension they are testing.)
488 =head1 Known Problems
490 Note that unlike other sections in this document (which describe
491 changes since 5.7.0) this section is cumulative containing known
492 problems for all the 5.7 releases.
500 If Perl is configured to use long doubles the op/int subtests 13 and
501 14 and the ext/POSIX subtest 14 may fail.
505 If Perl is configured to use threads the op/magic subtest 28 may fail.
509 vac 5.0.0.0 May Produce Buggy Code For Perl
511 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
512 resulting in few random tests failing, but when the failing tests
513 are run by hand, they succeed. We suggest upgrading to at least
514 vac version 5.0.1.0, that has been known to compile Perl correctly.
515 "lslpp -L|grep vac.C" will tell you the vac version.
519 =head2 Amiga Perl Invoking Mystery
521 One cannot call Perl using the C<volume:> syntax, that is, C<perl -v>
522 works, but for example C<bin:perl -v> doesn't. The exact reason is
523 known but the current suspect is the F<ixemul> library.
525 =head2 lib/ftmp-security tests warn 'system possibly insecure'
527 Don't panic. Read INSTALL 'make test' section instead.
529 =head Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
531 The subtests 11 and 12 sometimes fail and sometimes work.
533 =head2 HP-UX lib/io_multihomed Fails When LP64-Configur
535 The lib/io_multihomed test may hang in HP-UX if Perl has been
536 configured to be 64-bit. Because other 64-bit platforms do not hang in
537 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
538 test attempts to create and connect to "multihomed" sockets (sockets
539 which have multiple IP addresses).
541 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
543 If perl is configured with -Duse64bitall, the successful result of the
544 subtest 10 of lib/posix may arrive before the successful result of the
545 subtest 9, which confuses the test harness so much that it thinks the
548 =head2 Linux With Sfio Fails op/misc Test 48
552 =head2 op/sprintf tests 129 and 130
554 The op/sprintf tests 129 and 130 are known to fail on some platforms.
555 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
556 The failing platforms do not comply with the ANSI C Standard, line
557 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
558 something else than "1" and "-1" when formatting 0.6 and -0.6 using
559 the printf format "%.0f", most often they produce "0" and "-0".)
561 =head2 Failure of Thread tests
563 B<Note that support for 5.005-style threading remains experimental.>
565 The following tests are known to fail due to fundamental problems in
566 the 5.005 threading implementation. These are not new failures--Perl
567 5.005_0x has the same bugs, but didn't have these tests.
570 t/lib/thr5005.t 19-20
578 ext/POSIX/sigaction subtests 6 and 13 may fail.
582 lib/ExtUtils may spuriously claim that subtest 28 failed,
583 which is interesting since the test only has 27 tests.
587 Numerous numerical test failures
589 op/numconvert 209,210,217,218
591 ext/Time/HiRes/HiRes 9
592 lib/Math/BigInt/t/bigintpm 1145
595 These tests fail because of yet unresolved floating point inaccuracies.
599 =head2 UNICOS/mk ext/IPC/SysV/t/sem test 8
605 Many floating point inaccuracies:
607 op/numconvert 511,657,658,659,665-667,831,991,1151
608 op/pack 10,22,149,156
609 op/sprintf 8,10,13,102-107,134-135,146-153,159-162
610 lib/Math/BigInt/bigintpm 1145,1183
611 lib/Math/Complex 250,257,514,521,722-724,
612 934,935,945,949,955,956,975,976
615 =head2 Localising a Tied Variable Leaks Memory
618 tie my %tie_hash => 'Tie::StdHash';
622 local($tie_hash{Foo}) = 1; # leaks
624 Code like the above is known to leak memory every time the local()
627 =head2 Self-tying of Arrays and Hashes Is Forbidden
629 Self-tying of arrays and hashes is broken in rather deep and
630 hard-to-fix ways. As a stop-gap measure to avoid people from getting
631 frustrated at the mysterious results (core dumps, most often) it is
632 for now forbidden (you will get a fatal error even from an attempt).
634 =head2 Variable Attributes are not Currently Usable for Tieing
636 This limitation will hopefully be fixed in future. (Subroutine
637 attributes work fine for tieing, see L<Attribute::Handlers>).
639 =head2 Building Extensions Can Fail Because Of Largefiles
641 Some extensions like mod_perl are known to have issues with
642 `largefiles', a change brought by Perl 5.6.0 in which file offsets
643 default to 64 bits wide, where supported. Modules may fail to compile
644 at all or compile and work incorrectly. Currently there is no good
645 solution for the problem, but Configure now provides appropriate
646 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
647 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
648 having problems can try configuring themselves without the
649 largefileness. This is admittedly not a clean solution, and the
650 solution may not even work at all. One potential failure is whether
651 one can (or, if one can, whether it's a good idea) link together at
652 all binaries with different ideas about file offsets, all this is
655 =head2 The Compiler Suite Is Still Experimental
657 The compiler suite is slowly getting better but is nowhere near
660 =head2 The Long Double Support is Still Experimental
662 The ability to configure Perl's numbers to use "long doubles",
663 floating point numbers of hopefully better accuracy, is still
664 experimental. The implementations of long doubles are not yet
665 widespread and the existing implementations are not quite mature
666 or standardised, therefore trying to support them is a rare
667 and moving target. The gain of more precision may also be offset
668 by slowdown in computations (more bits to move around, and the
669 operations are more likely to be executed by less optimised
672 =head1 Reporting Bugs
674 If you find what you think is a bug, you might check the articles
675 recently posted to the comp.lang.perl.misc newsgroup and the perl
676 bug database at http://bugs.perl.org. There may also be
677 information at http://www.perl.com/perl/, the Perl Home Page.
679 If you believe you have an unreported bug, please run the B<perlbug>
680 program included with your release. Be sure to trim your bug down
681 to a tiny but sufficient test case. Your bug report, along with the
682 output of C<perl -V>, will be sent off to perlbug@perl.org to be
683 analysed by the Perl porting team.
687 The F<Changes> file for exhaustive details on what changed.
689 The F<INSTALL> file for how to build Perl.
691 The F<README> file for general stuff.
693 The F<Artistic> and F<Copying> files for copyright information.
697 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
698 from The Perl Porters and Perl Users submitting feedback and patches.
700 Send omissions or corrections to <F<perlbug@perl.org>>.