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 If your pointers are 64 bits wide, the Perl malloc is no more being
33 used because it simply does not work with 8-byte pointers. Also,
34 usually the system malloc on such platforms are much better optimized
35 for such large memory models than the Perl malloc.
37 =head1 Future Deprecations
39 The current user-visible implementation of pseudo-hashes (the weird
40 use of the first array element) is deprecated starting from Perl 5.8.0
41 and will be removed in Perl 5.10.0, and the feature will be implemented
42 differently. Not only is the current interface rather ugly, but the
43 current implementation slows down normal array and hash use quite
44 noticeably. The 'fields' pragma interface will remain available.
46 The suidperl is also considered to be too much a risk to continue
47 maintaining and the suidperl code is likely to be removed in a future
50 =head1 Core Enhancements
52 In general a lot of fixing has happened in the area of Perl's understanding
53 of numbers, both integer and floating point. Since in many systems the
54 standard number parsing functions like C<strtoul()> and C<atof()> seem
55 to have bugs, Perl tries to work around their deficiencies. This results
56 hopefully in more accurate numbers.
62 The rules for allowing underscores (underbars) in numeric constants
63 have been relaxed and simplified: now you can have an underscore
68 VMS now works under PerlIO.
72 GMAGIC (right-hand side magic) could in many cases such as concatenation
73 of string be invoked too many times.
77 The MAGIC constants (e.g. C<'P'>) have been macrofied
78 (e.g. C<PERL_MAGIC_TIED>) for better source code readability
83 The C<op_clear> and C<op_null> are now exported.
87 The Perl parser has been stress tested using both random input and
92 =head1 Modules and Pragmata
100 Attribute::Handlers - Simpler definition of attribute handlers
104 ExtUtils::Constant - generate XS code to import C header constants
108 I18N::LangTags - functions for dealing with RFC3066-style language tags
112 List::Util - selection of general-utility list subroutines
116 Locale::Maketext - framework for localization
120 NEXT - pseudo-class for method redispatch
124 Scalar::Util - selection of general-utility scalar subroutines
128 Time::HiRes - high resolution ualarm, usleep, and gettimeofday
132 =head2 Updated And Improved Modules and Pragmata
138 L<B::Deparse> module has been significantly enhanced. It now
139 can deparse almost all of the standard test suite (so that the
140 tests still succeed).
144 L<Class::Struct> now assigns the array/hash element if the accessor
145 is called with an array/hash element as the B<sole> argument.
149 L<Cwd> extension is now (even) faster.
153 L<DB_File> extension has been updated to version 1.77.
157 L<Fcntl>, L<Socket>, and L<Sys::Syslog> have been rewritten to use the
158 new-style constant dispatch section (see L<ExtUtils::Constant>).
162 L<File::Glob> now supports C<GLOB_LIMIT> constant to limit the
163 size of the returned list of filenames.
167 =head1 Performance Enhancements
169 =head1 Utility Changes
175 L<h2xs> uses the new L<ExtUtils::Constant> module which will affect
176 newly created extensions that define constants. Since the new code is
177 more correct (if you have two constants where the first one is a
178 prefix of the second one, the first constant B<never> gets defined),
179 less lossy (it uses integers for integer constant, as opposed to the
180 old code that used floating point numbers even for integer constants),
181 and slightly faster, you might want to consider regenerating your
182 extension code (the new scheme makes regenerating easy).
186 The F<emacs/e2ctags.pl> is now much faster.
190 The F<Pod::Html> (and thusly L<pod2html>) now allows specifying
195 =head1 New Documentation
201 L<Locale::Maketext::TPJ13> is an article about software localization,
202 originally published in The Perl Journal #13, republished here with
207 More README.$PLATFORM files have been converted into pod, which also
208 means that they also be installed as perl$PLATFORM documentation
209 files. The new files are L<perlapollo>, L<perlbeos>, L<perldgux>,
210 L<perlhurd>, L<perlmint>, L<perlplan9>, L<perlqnx>, and L<perltru64>.
214 The F<Todo> and F<Todo-5.6> files have been merged into L<perltodo>.
218 Use of the F<gprof> tool to profile Perl has been documented in L<perlhack>.
222 =head1 Installation and Configuration Improvements
224 =head2 New Or Improved Platforms
230 AIX should now work better with gcc. Also longdouble support in
231 AIX should be better now.
235 AtheOS (http://www.atheos.cx/) is a new platform.
239 DG/UX platform now supports the 5.005-style threads.
243 MacOS (Classic) [HOPEFULLY]
247 MacOS X (or Darwin) should now be able to build Perl even on HFS+ filesystem.
248 (The case-insensitivity confused the Perl build process.)
256 The Amdahl UTS UNIX mainframe platform is now supported.
260 =head2 Generic Improvements
266 The C code has been made much more C<gcc -Wall> clean. Some warning
267 messages still remain, though, so if you are compiling with gcc you
268 will see some warnings about dubious practices. The warnings are
273 In AFS installations one can configure the root of the AFS to be
274 somewhere else than the default F</afs> by using the Configure
275 parameter C<-Dafsroot=/some/where/else>.
279 The version of Berkeley DB used when the Perl (and, presumably, the
280 DB_File extension) was built is now available as
281 C<@Config{qw(db_version_major db_version_minor db_version_patch)}>
282 from Perl and as C<DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
283 DB_VERSION_PATCH_CFG> from C.
287 The Thread extension is not built at all under ithreads (C<Configure
288 -Duseithreads>) because it wouldn't work anyway (the Thread extension
289 requires being Configured with C<-Duse5005threads>).
293 The C<B::Deparse> compiler backend has been so significantly improved
294 that almost the whole Perl test suite passes after being deparsed. A
295 make target has been added to help in further testing: C<make test.deparse>.
299 =head1 Selected Bug Fixes
301 =head2 Platform Specific Changes and Fixes
307 Some versions of glibc have a broken modfl(). This affects builds
308 with C<-Duselongdouble>. This version of Perl detects this brokenness
309 and has a workaround for it. The glibc release 2.2.2 is known to have
310 fixed the modfl() bug.
314 =head1 New or Changed Diagnostics
320 In the regular expression diagnostics the C<E<lt>E<lt> HERE> marker
321 introduced in 5.7.0 has been changed to be C<E<lt>-- HERE> since too
322 many people found the C<E<lt>E<lt>> to be too similar to here-document
327 If you try to L<perlfunc/pack> a number less than 0 or larger than 255
328 using the C<"C"> format you will get an optional warning. Similarly
329 for the C<"c"> format and a number less than -128 or more than 127.
333 Certain regex modifiers such as C<(?o)> make sense only if applied to
334 the entire regex. You will an optional warning if you try to do otherwise.
338 Using arrays or hashes as references (e.g. C<%foo->{bar}> has been
339 deprecated for a while. Now you will get an optional warning.
343 =head1 Changed Internals
345 =head2 Regex pre-/post-compilation items matched up
347 The regex compiler now maintains a structure that identifies nodes in
348 the compiled bytecode with the corresponding syntactic features of the
349 original regex expression. The information is attached to the new
350 C<offsets> member of the C<struct regexp>. See L<perldebguts> for more
351 complete information.
355 Several new tests have been added, especially for the F<lib> subsection.
359 The test F<camel-III/vstring> has been merged with F<op/ver>.
361 =head1 Known Problems
363 Note that unlike other sections in this document (which describe
364 changes since 5.7.0) this section is cumulative containing known
365 problems for all the 5.7 releases.
367 =head2 AIX vac 5.0.0.0 May Produce Buggy Code For Perl
369 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
370 resulting in few random tests failing, but when the failing tests
371 are run by hand, they succeed. We suggest upgrading to at least
372 vac version 5.0.1.0, that has been known to compile Perl correctly.
373 "lslpp -L|grep vac.C" will tell you the vac version.
375 =head2 lib/ftmp-security tests warn 'system possibly insecure'
377 Don't panic. Read INSTALL 'make test' section instead.
379 =head2 lib/io_multihomed Fails In LP64-Configured HP-UX
381 The lib/io_multihomed test may hang in HP-UX if Perl has been
382 configured to be 64-bit. Because other 64-bit platforms do not hang in
383 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
384 test attempts to create and connect to "multihomed" sockets (sockets
385 which have multiple IP addresses).
387 =head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
389 If perl is configured with -Duse64bitall, the successful result of the
390 subtest 10 of lib/posix may arrive before the successful result of the
391 subtest 9, which confuses the test harness so much that it thinks the
396 The test fails on various platforms (PA64 and IA64 are known), but the
397 exact cause is still being investigated.
399 =head2 Linux With Sfio Fails op/misc Test 48
403 =head2 sigaction test 13 in VMS
405 The test is known to fail; whether it's because of VMS of because
406 of faulty test is not known.
408 =head2 sprintf tests 129 and 130
410 The op/sprintf tests 129 and 130 are known to fail on some platforms.
411 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
412 The failing platforms do not comply with the ANSI C Standard, line
413 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
414 something else than "1" and "-1" when formatting 0.6 and -0.6 using
415 the printf format "%.0f", most often they produce "0" and "-0".)
417 =head2 Failure of Thread tests
419 B<Note that support for 5.005-style threading remains experimental.>
421 The following tests are known to fail due to fundamental problems in
422 the 5.005 threading implementation. These are not new failures--Perl
423 5.005_0x has the same bugs, but didn't have these tests.
425 lib/Memoize/t/correctness.t 23-25
426 lib/Memoize/t/unmemoize.t 2-5
428 t/lib/thr5005.t 19-20
430 =head2 Localising a Tied Variable Leaks Memory
433 tie my %tie_hash => 'Tie::StdHash';
437 local($tie_hash{Foo}) = 1; # leaks
439 Code like the above is known to leak memory every time the local()
442 =head2 Self-tying of Arrays and Hashes Is Forbidden
444 Self-tying of arrays and hashes is broken in rather deep and
445 hard-to-fix ways. As a stop-gap measure to avoid people from getting
446 frustrated at the mysterious results (core dumps, most often) it is
447 for now forbidden (you will get a fatal error even from an attempt).
449 =head2 Building Extensions Can Fail Because Of Largefiles
451 Some extensions like mod_perl are known to have issues with
452 `largefiles', a change brought by Perl 5.6.0 in which file offsets
453 default to 64 bits wide, where supported. Modules may fail to compile
454 at all or compile and work incorrectly. Currently there is no good
455 solution for the problem, but Configure now provides appropriate
456 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
457 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
458 having problems can try configuring themselves without the
459 largefileness. This is admittedly not a clean solution, and the
460 solution may not even work at all. One potential failure is whether
461 one can (or, if one can, whether it's a good idea) link together at
462 all binaries with different ideas about file offsets, all this is
465 =head2 The Compiler Suite Is Still Experimental
467 The compiler suite is slowly getting better but is nowhere near
470 =head1 Reporting Bugs
472 If you find what you think is a bug, you might check the articles
473 recently posted to the comp.lang.perl.misc newsgroup and the perl
474 bug database at http://bugs.perl.org. There may also be
475 information at http://www.perl.com/perl/, the Perl Home Page.
477 If you believe you have an unreported bug, please run the B<perlbug>
478 program included with your release. Be sure to trim your bug down
479 to a tiny but sufficient test case. Your bug report, along with the
480 output of C<perl -V>, will be sent off to perlbug@perl.org to be
481 analysed by the Perl porting team.
485 The F<Changes> file for exhaustive details on what changed.
487 The F<INSTALL> file for how to build Perl.
489 The F<README> file for general stuff.
491 The F<Artistic> and F<Copying> files for copyright information.
495 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
496 from The Perl Porters and Perl Users submitting feedback and patches.
498 Send omissions or corrections to <F<perlbug@perl.org>>.