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 Future Deprecations
41 The current user-visible implementation of pseudo-hashes (the weird
42 use of the first array element) is deprecated starting from Perl 5.8.0
43 and will be removed in Perl 5.10.0, and the feature will be implemented
44 differently. Not only is the current interface rather ugly, but the
45 current implementation slows down normal array and hash use quite
46 noticeably. The 'fields' pragma interface will remain available.
48 The suidperl is also considered to be too much a risk to continue
49 maintaining and the suidperl code is likely to be removed in a future
52 =head1 Core Enhancements
54 In general a lot of fixing has happened in the area of Perl's understanding
55 of numbers, both integer and floating point. Since in many systems the
56 standard number parsing functions like C<strtoul()> and C<atof()> seem
57 to have bugs, Perl tries to work around their deficiencies. This results
58 hopefully in more accurate numbers.
64 The rules for allowing underscores (underbars) in numeric constants
65 have been relaxed and simplified: now you can have an underscore
70 VMS now works under PerlIO.
74 GMAGIC (right-hand side magic) could in many cases such as concatenation
75 of string be invoked too many times.
79 The MAGIC constants (e.g. C<'P'>) have been macrofied
80 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
85 The C<op_clear> and C<op_null> are now exported.
89 L<utime> now supports C<utime undef, undef, @files> to change the
90 times to the current time.
94 The Perl parser has been stress tested using both random input and
99 =head1 Modules and Pragmata
101 =head2 New Modules and Distribution
107 L<Attribute::Handlers> - Simpler definition of attribute handlers
111 L<ExtUtils::Constant> - generate XS code to import C header constants
115 L<I18N::LangTags> - functions for dealing with RFC3066-style language tags
119 L<libnet> - a collection of perl5 modules related to network programming
123 L<List::Util> - selection of general-utility list subroutines
127 L<Locale::Maketext> - framework for localization
131 L<Memoize> - Make your functions faster by trading space for time
135 L<NEXT> - pseudo-class for method redispatch
139 L<Scalar::Util> - selection of general-utility scalar subroutines
143 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
147 L<Time::Piece> - Object Oriented time objects
151 =head2 Updated And Improved Modules and Pragmata
157 L<B::Deparse> module has been significantly enhanced. It now
158 can deparse almost all of the standard test suite (so that the
159 tests still succeed). There is a make target "test.deparse"
164 L<Class::Struct> now assigns the array/hash element if the accessor
165 is called with an array/hash element as the B<sole> argument.
169 L<Cwd> extension is now (even) faster.
173 L<DB_File> extension has been updated to version 1.77.
177 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
178 new-style constant dispatch section (see L<ExtUtils::Constant>).
182 L<File::Find> is now (again) reentrant. It also has been made
187 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
188 size of the returned list of filenames.
192 L<vars> now supports declaring qualified variables.
196 =head1 Utility Changes
202 The F<emacs/e2ctags.pl> is now much faster.
206 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
207 newly created extensions that define constants. Since the new code is
208 more correct (if you have two constants where the first one is a
209 prefix of the second one, the first constant B<never> gets defined),
210 less lossy (it uses integers for integer constant, as opposed to the
211 old code that used floating point numbers even for integer constants),
212 and slightly faster, you might want to consider regenerating your
213 extension code (the new scheme makes regenerating easy).
217 L<libnetcfg> has been added to configure the libnet.
221 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
226 =head1 New Documentation
232 L<Locale::Maketext::TPJ13> is an article about software localization,
233 originally published in The Perl Journal #13, republished here with
238 More README.$PLATFORM files have been converted into pod, which also
239 means that they also be installed as perl$PLATFORM documentation
240 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
241 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
246 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
250 Use of the F<gprof> tool to profile Perl has been documented in
251 L<perlhack>. There is a make target "perl.gprof" for generating a
252 gprofiled Perl executable.
256 =head1 Installation and Configuration Improvements
258 =head2 New Or Improved Platforms
264 AIX should now work better with gcc. Also longdouble support in AIX
265 should be better now. See L<perlaix>.
269 AtheOS (http://www.atheos.cx/) is a new platform.
273 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
277 Several MacOS (Classic) portability patches have been applied. We
278 hope to get a fully working port by 5.8.0. (The remaining problems
279 relate to the changed IO model of Perl.) See L<perlmacos>.
283 MacOS X (or Darwin) should now be able to build Perl even on HFS+
284 filesystems. (The case-insensitivity confused the Perl build process.)
288 NetWare from Novell is now supported. See L<perlnetware>.
292 The Amdahl UTS UNIX mainframe platform is now supported.
296 =head2 Generic Improvements
302 The C code has been made much more C<gcc -Wall> clean. Some warning
303 messages still remain, though, so if you are compiling with gcc you
304 will see some warnings about dubious practices. The warnings are
309 In AFS installations one can configure the root of the AFS to be
310 somewhere else than the default F</afs> by using the Configure
311 parameter C<-Dafsroot=/some/where/else>.
315 The version of Berkeley DB used when the Perl (and, presumably, the
316 DB_File extension) was built is now available as
317 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
318 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
319 DB_VERSION_PATCH_CFG> from C.
323 The Thread extension is now not built at all under ithreads
324 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
325 Thread extension requires being Configured with C<-Duse5005threads>).
329 The C<B::Deparse> compiler backend has been so significantly improved
330 that almost the whole Perl test suite passes after being deparsed. A
331 make target has been added to help in further testing: C<make test.deparse>.
335 =head1 Selected Bug Fixes
341 The autouse pragma didn't work for Multi::Part::Function::Names.
345 The behaviour of non-decimal but numeric string constants such as
346 "0x23" was platform-dependent: in some platforms that was seen as 35,
347 in some as 0, in some as a floating point number (don't ask). This
348 was caused by Perl using the operating system libraries in a situation
349 where the result of the string to number conversion is undefined: now
350 Perl consistently handles such strings as zero in numeric contexts.
354 L<dprofpp> -R didn't work.
358 PERL5OPT with embedded spaces didn't work.
362 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
366 =head2 Platform Specific Changes and Fixes
372 Some versions of glibc have a broken modfl(). This affects builds
373 with C<-Duselongdouble>. This version of Perl detects this brokenness
374 and has a workaround for it. The glibc release 2.2.2 is known to have
375 fixed the modfl() bug.
379 =head1 New or Changed Diagnostics
385 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
386 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
387 many people found the C<E<lt>E<lt>> to be too similar to here-document
392 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
393 using the C<"C"> format you will get an optional warning. Similarly
394 for the C<"c"> format and a number less than -128 or more than 127.
398 Certain regex modifiers such as C<(?o)> make sense only if applied to
399 the entire regex. You will an optional warning if you try to do otherwise.
403 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
404 deprecated for a while. Now you will get an optional warning.
408 =head1 Changed Internals
410 =head2 Regex pre-/post-compilation items matched up
412 The regex compiler now maintains a structure that identifies nodes in
413 the compiled bytecode with the corresponding syntactic features of the
414 original regex expression. The information is attached to the new
415 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
416 complete information.
420 Several new tests have been added, especially for the F<lib> subsection.
422 The tests are now reported in a different order than in earlier Perls.
423 (This happens because the test scripts from under t/lib have been moved
424 to be closer to the library/extension they are testing.)
426 =head1 Known Problems
428 Note that unlike other sections in this document (which describe
429 changes since 5.7.0) this section is cumulative containing known
430 problems for all the 5.7 releases.
432 =head2 AIX vac 5.0.0.0 May Produce Buggy Code For Perl
434 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
435 resulting in few random tests failing, but when the failing tests
436 are run by hand, they succeed. We suggest upgrading to at least
437 vac version 5.0.1.0, that has been known to compile Perl correctly.
438 "lslpp -L|grep vac.C" will tell you the vac version.
440 =head2 lib/ftmp-security tests warn 'system possibly insecure'
442 Don't panic. Read INSTALL 'make test' section instead.
444 =head2 lib/io_multihomed Fails In LP64-Configured HP-UX
446 The lib/io_multihomed test may hang in HP-UX if Perl has been
447 configured to be 64-bit. Because other 64-bit platforms do not hang in
448 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
449 test attempts to create and connect to "multihomed" sockets (sockets
450 which have multiple IP addresses).
452 =head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
454 If perl is configured with -Duse64bitall, the successful result of the
455 subtest 10 of lib/posix may arrive before the successful result of the
456 subtest 9, which confuses the test harness so much that it thinks the
461 The test fails on various platforms (PA64 and IA64 are known), but the
462 exact cause is still being investigated.
464 =head2 Linux With Sfio Fails op/misc Test 48
468 =head2 sigaction test 13 in VMS
470 The test is known to fail; whether it's because of VMS of because
471 of faulty test is not known.
473 =head2 sprintf tests 129 and 130
475 The op/sprintf tests 129 and 130 are known to fail on some platforms.
476 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
477 The failing platforms do not comply with the ANSI C Standard, line
478 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
479 something else than "1" and "-1" when formatting 0.6 and -0.6 using
480 the printf format "%.0f", most often they produce "0" and "-0".)
482 =head2 Failure of Thread tests
484 B<Note that support for 5.005-style threading remains experimental.>
486 The following tests are known to fail due to fundamental problems in
487 the 5.005 threading implementation. These are not new failures--Perl
488 5.005_0x has the same bugs, but didn't have these tests.
490 lib/Memoize/t/correctness.t 23-25
491 lib/Memoize/t/unmemoize.t 2-5
493 t/lib/thr5005.t 19-20
495 =head2 Localising a Tied Variable Leaks Memory
498 tie my %tie_hash => 'Tie::StdHash';
502 local($tie_hash{Foo}) = 1; # leaks
504 Code like the above is known to leak memory every time the local()
507 =head2 Self-tying of Arrays and Hashes Is Forbidden
509 Self-tying of arrays and hashes is broken in rather deep and
510 hard-to-fix ways. As a stop-gap measure to avoid people from getting
511 frustrated at the mysterious results (core dumps, most often) it is
512 for now forbidden (you will get a fatal error even from an attempt).
514 =head2 Variable Attributes are not Currently Usable for Tieing
516 This limitation will hopefully be fixed in future. (Subroutine
517 attributes work fine for tieing, see L<Attribute::Handlers>).
519 =head2 Building Extensions Can Fail Because Of Largefiles
521 Some extensions like mod_perl are known to have issues with
522 `largefiles', a change brought by Perl 5.6.0 in which file offsets
523 default to 64 bits wide, where supported. Modules may fail to compile
524 at all or compile and work incorrectly. Currently there is no good
525 solution for the problem, but Configure now provides appropriate
526 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
527 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
528 having problems can try configuring themselves without the
529 largefileness. This is admittedly not a clean solution, and the
530 solution may not even work at all. One potential failure is whether
531 one can (or, if one can, whether it's a good idea) link together at
532 all binaries with different ideas about file offsets, all this is
535 =head2 The Compiler Suite Is Still Experimental
537 The compiler suite is slowly getting better but is nowhere near
540 =head1 Reporting Bugs
542 If you find what you think is a bug, you might check the articles
543 recently posted to the comp.lang.perl.misc newsgroup and the perl
544 bug database at http://bugs.perl.org. There may also be
545 information at http://www.perl.com/perl/, the Perl Home Page.
547 If you believe you have an unreported bug, please run the B<perlbug>
548 program included with your release. Be sure to trim your bug down
549 to a tiny but sufficient test case. Your bug report, along with the
550 output of C<perl -V>, will be sent off to perlbug@perl.org to be
551 analysed by the Perl porting team.
555 The F<Changes> file for exhaustive details on what changed.
557 The F<INSTALL> file for how to build Perl.
559 The F<README> file for general stuff.
561 The F<Artistic> and F<Copying> files for copyright information.
565 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
566 from The Perl Porters and Perl Users submitting feedback and patches.
568 Send omissions or corrections to <F<perlbug@perl.org>>.