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<Test::More> - yet another framework for writing test scripts
147 L<Test::Simple> - Basic utilities for writing tests
151 L<Time::HiRes> - high resolution ualarm, usleep, and gettimeofday
155 L<Time::Piece> - Object Oriented time objects
159 =head2 Updated And Improved Modules and Pragmata
165 L<B::Deparse> module has been significantly enhanced. It now
166 can deparse almost all of the standard test suite (so that the
167 tests still succeed). There is a make target "test.deparse"
172 L<Class::Struct> now assigns the array/hash element if the accessor
173 is called with an array/hash element as the B<sole> argument.
177 L<Cwd> extension is now (even) faster.
181 L<DB_File> extension has been updated to version 1.77.
185 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
186 new-style constant dispatch section (see L<ExtUtils::Constant>).
190 L<File::Find> is now (again) reentrant. It also has been made
195 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
196 size of the returned list of filenames.
200 L<vars> now supports declaring qualified variables.
204 =head1 Utility Changes
210 The F<emacs/e2ctags.pl> is now much faster.
214 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
215 newly created extensions that define constants. Since the new code is
216 more correct (if you have two constants where the first one is a
217 prefix of the second one, the first constant B<never> gets defined),
218 less lossy (it uses integers for integer constant, as opposed to the
219 old code that used floating point numbers even for integer constants),
220 and slightly faster, you might want to consider regenerating your
221 extension code (the new scheme makes regenerating easy).
225 L<libnetcfg> has been added to configure the libnet.
229 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
234 =head1 New Documentation
240 L<Locale::Maketext::TPJ13> is an article about software localization,
241 originally published in The Perl Journal #13, republished here with
246 More README.$PLATFORM files have been converted into pod, which also
247 means that they also be installed as perl$PLATFORM documentation
248 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
249 L<perlhurd>, L<perlmint>, L<perlnetware>, L<perlplan9>, L<perlqnx>,
254 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
258 Use of the F<gprof> tool to profile Perl has been documented in
259 L<perlhack>. There is a make target "perl.gprof" for generating a
260 gprofiled Perl executable.
264 =head1 Installation and Configuration Improvements
266 =head2 New Or Improved Platforms
272 AIX should now work better with gcc. Also longdouble support in AIX
273 should be better now. See L<perlaix>.
277 AtheOS (http://www.atheos.cx/) is a new platform.
281 DG/UX platform now supports the 5.005-style threads. See L<perldgux>.
285 Several MacOS (Classic) portability patches have been applied. We
286 hope to get a fully working port by 5.8.0. (The remaining problems
287 relate to the changed IO model of Perl.) See L<perlmacos>.
291 MacOS X (or Darwin) should now be able to build Perl even on HFS+
292 filesystems. (The case-insensitivity confused the Perl build process.)
296 NetWare from Novell is now supported. See L<perlnetware>.
300 The Amdahl UTS UNIX mainframe platform is now supported.
304 =head2 Generic Improvements
310 The C code has been made much more C<gcc -Wall> clean. Some warning
311 messages still remain, though, so if you are compiling with gcc you
312 will see some warnings about dubious practices. The warnings are
317 In AFS installations one can configure the root of the AFS to be
318 somewhere else than the default F</afs> by using the Configure
319 parameter C<-Dafsroot=/some/where/else>.
323 The version of Berkeley DB used when the Perl (and, presumably, the
324 DB_File extension) was built is now available as
325 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
326 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
327 DB_VERSION_PATCH_CFG> from C.
331 The Thread extension is now not built at all under ithreads
332 (C<Configure -Duseithreads>) because it wouldn't work anyway (the
333 Thread extension requires being Configured with C<-Duse5005threads>).
337 The C<B::Deparse> compiler backend has been so significantly improved
338 that almost the whole Perl test suite passes after being deparsed. A
339 make target has been added to help in further testing: C<make test.deparse>.
343 =head1 Selected Bug Fixes
349 The autouse pragma didn't work for Multi::Part::Function::Names.
353 The behaviour of non-decimal but numeric string constants such as
354 "0x23" was platform-dependent: in some platforms that was seen as 35,
355 in some as 0, in some as a floating point number (don't ask). This
356 was caused by Perl using the operating system libraries in a situation
357 where the result of the string to number conversion is undefined: now
358 Perl consistently handles such strings as zero in numeric contexts.
362 L<dprofpp> -R didn't work.
366 PERL5OPT with embedded spaces didn't work.
370 L<Sys::Syslog> ignored the C<LOG_AUTH> constant.
374 =head2 Platform Specific Changes and Fixes
380 Some versions of glibc have a broken modfl(). This affects builds
381 with C<-Duselongdouble>. This version of Perl detects this brokenness
382 and has a workaround for it. The glibc release 2.2.2 is known to have
383 fixed the modfl() bug.
387 =head1 New or Changed Diagnostics
393 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
394 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
395 many people found the C<E<lt>E<lt>> to be too similar to here-document
400 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
401 using the C<"C"> format you will get an optional warning. Similarly
402 for the C<"c"> format and a number less than -128 or more than 127.
406 Certain regex modifiers such as C<(?o)> make sense only if applied to
407 the entire regex. You will an optional warning if you try to do otherwise.
411 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
412 deprecated for a while. Now you will get an optional warning.
416 =head1 Changed Internals
418 =head2 Regex pre-/post-compilation items matched up
420 The regex compiler now maintains a structure that identifies nodes in
421 the compiled bytecode with the corresponding syntactic features of the
422 original regex expression. The information is attached to the new
423 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
424 complete information.
428 Several new tests have been added, especially for the F<lib> subsection.
430 The tests are now reported in a different order than in earlier Perls.
431 (This happens because the test scripts from under t/lib have been moved
432 to be closer to the library/extension they are testing.)
434 =head1 Known Problems
436 Note that unlike other sections in this document (which describe
437 changes since 5.7.0) this section is cumulative containing known
438 problems for all the 5.7 releases.
446 If Perl is configured to use long doubles the op/int subtests 13 and
447 14 and the ext/POSIX subtest 14 may fail.
451 If Perl is configured to use threads the op/magic subtest 28 may fail.
455 vac 5.0.0.0 May Produce Buggy Code For Perl
457 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
458 resulting in few random tests failing, but when the failing tests
459 are run by hand, they succeed. We suggest upgrading to at least
460 vac version 5.0.1.0, that has been known to compile Perl correctly.
461 "lslpp -L|grep vac.C" will tell you the vac version.
465 =head2 lib/ftmp-security tests warn 'system possibly insecure'
467 Don't panic. Read INSTALL 'make test' section instead.
469 =head Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and 12
471 The subtests 11 and 12 sometimes fail and sometimes work.
473 =head2 HP-UX lib/io_multihomed Fails When LP64-Configur
475 The lib/io_multihomed test may hang in HP-UX if Perl has been
476 configured to be 64-bit. Because other 64-bit platforms do not hang in
477 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
478 test attempts to create and connect to "multihomed" sockets (sockets
479 which have multiple IP addresses).
481 =head2 HP-UX lib/posix Subtest 9 Fails When LP64-Configured
483 If perl is configured with -Duse64bitall, the successful result of the
484 subtest 10 of lib/posix may arrive before the successful result of the
485 subtest 9, which confuses the test harness so much that it thinks the
488 =head2 Linux With Sfio Fails op/misc Test 48
492 =head2 op/sprintf tests 129 and 130
494 The op/sprintf tests 129 and 130 are known to fail on some platforms.
495 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
496 The failing platforms do not comply with the ANSI C Standard, line
497 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
498 something else than "1" and "-1" when formatting 0.6 and -0.6 using
499 the printf format "%.0f", most often they produce "0" and "-0".)
501 =head2 Failure of Thread tests
503 B<Note that support for 5.005-style threading remains experimental.>
505 The following tests are known to fail due to fundamental problems in
506 the 5.005 threading implementation. These are not new failures--Perl
507 5.005_0x has the same bugs, but didn't have these tests.
510 t/lib/thr5005.t 19-20
518 ext/POSIX/sigaction subtests 6 and 13 may fail.
522 lib/ExtUtils may spuriously claim that subtest 28 failed,
523 which is interesting since the test only has 27 tests.
527 Numerous numerical test failures
529 op/numconvert 209,210,217,218
531 ext/Time/HiRes/HiRes 9
532 lib/Math/BigInt/t/bigintpm 1145
535 These tests fail because of yet unresolved floating point inaccuracies.
539 =head2 UNICOS/mk ext/IPC/SysV/t/sem test 8
545 Many floating point inaccuracies:
547 op/numconvert 511,657,658,659,665-667,831,991,1151
548 op/pack 10,22,149,156
549 op/sprintf 8,10,13,102-107,134-135,146-153,159-162
550 lib/Math/BigInt/bigintpm 1145,1183
551 lib/Math/Complex 250,257,514,521,722-724,
552 934,935,945,949,955,956,975,976
555 =head2 Localising a Tied Variable Leaks Memory
558 tie my %tie_hash => 'Tie::StdHash';
562 local($tie_hash{Foo}) = 1; # leaks
564 Code like the above is known to leak memory every time the local()
567 =head2 Self-tying of Arrays and Hashes Is Forbidden
569 Self-tying of arrays and hashes is broken in rather deep and
570 hard-to-fix ways. As a stop-gap measure to avoid people from getting
571 frustrated at the mysterious results (core dumps, most often) it is
572 for now forbidden (you will get a fatal error even from an attempt).
574 =head2 Variable Attributes are not Currently Usable for Tieing
576 This limitation will hopefully be fixed in future. (Subroutine
577 attributes work fine for tieing, see L<Attribute::Handlers>).
579 =head2 Building Extensions Can Fail Because Of Largefiles
581 Some extensions like mod_perl are known to have issues with
582 `largefiles', a change brought by Perl 5.6.0 in which file offsets
583 default to 64 bits wide, where supported. Modules may fail to compile
584 at all or compile and work incorrectly. Currently there is no good
585 solution for the problem, but Configure now provides appropriate
586 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
587 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
588 having problems can try configuring themselves without the
589 largefileness. This is admittedly not a clean solution, and the
590 solution may not even work at all. One potential failure is whether
591 one can (or, if one can, whether it's a good idea) link together at
592 all binaries with different ideas about file offsets, all this is
595 =head2 The Compiler Suite Is Still Experimental
597 The compiler suite is slowly getting better but is nowhere near
600 =head2 The Long Double Support is Still Experimental
602 The ability to configure Perl's numbers to use "long doubles",
603 floating point numbers of hopefully better accuracy, is still
604 experimental. The implementations of long doubles are not yet
605 widespread and the existing implementations are not quite mature
606 or standardised, therefore trying to support them is a rare
607 and moving target. The gain of more precision may also be offset
608 by slowdown in computations (more bits to move around, and the
609 operations are more likely to be executed by less optimised
612 =head1 Reporting Bugs
614 If you find what you think is a bug, you might check the articles
615 recently posted to the comp.lang.perl.misc newsgroup and the perl
616 bug database at http://bugs.perl.org. There may also be
617 information at http://www.perl.com/perl/, the Perl Home Page.
619 If you believe you have an unreported bug, please run the B<perlbug>
620 program included with your release. Be sure to trim your bug down
621 to a tiny but sufficient test case. Your bug report, along with the
622 output of C<perl -V>, will be sent off to perlbug@perl.org to be
623 analysed by the Perl porting team.
627 The F<Changes> file for exhaustive details on what changed.
629 The F<INSTALL> file for how to build Perl.
631 The F<README> file for general stuff.
633 The F<Artistic> and F<Copying> files for copyright information.
637 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
638 from The Perl Porters and Perl Users submitting feedback and patches.
640 Send omissions or corrections to <F<perlbug@perl.org>>.