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1=head1 NAME
2
3perl570delta - what's new for perl v5.7.0
4
5=head1 DESCRIPTION
6
7This document describes differences between the 5.6.0 release and
8the 5.7.0 release.
9
10=head1 Security Vulnerability Closed
11
12A potential security vulnerability in the optional suidperl component
13of Perl has been identified. suidperl is neither built nor installed
14by default. As of September the 2nd, 2000, the only known vulnerable
15platform is Linux, most likely all Linux distributions. CERT and
16various vendors have been alerted about the vulnerability.
17
18The problem was caused by Perl trying to report a suspected security
19exploit attempt using an external program, /bin/mail. On Linux
20platforms the /bin/mail program had an undocumented feature which
21when combined with suidperl gave access to a root shell, resulting in
22a serious compromise instead of reporting the exploit attempt. If you
23don't have /bin/mail, or if you have 'safe setuid scripts', or if
24suidperl is not installed, you are safe.
25
26The exploit attempt reporting feature has been completely removed from
27the Perl 5.7.0 release, so that particular vulnerability isn't there
28anymore. However, further security vulnerabilities are,
29unfortunately, always possible. The suidperl code is being reviewed
30and if deemed too risky to continue to be supported, it may be
31completely removed from future releases. In any case, suidperl should
32only be used by security experts who know exactly what they are doing
33and why they are using suidperl instead of some other solution such as
34sudo (see http://www.courtesan.com/sudo/).
35
36=head1 Incompatible Changes
37
38=over 4
39
40=item *
41
42Arrays now always interpolate into double-quoted strings:
43constructs like "foo@bar" now always assume C<@bar> is an array,
44whether or not the compiler has seen use of C<@bar>.
45
46=item *
47
48The semantics of bless(REF, REF) were unclear and until someone proves
49it to make some sense, it is forbidden.
50
51=item *
52
53A reference to a reference now stringify as "REF(0x81485ec)" instead
54of "SCALAR(0x81485ec)" in order to be more consistent with the return
55value of ref().
56
57=item *
58
59The very dusty examples in the eg/ directory have been removed.
60Suggestions for new shiny examples welcome but the main issue is that
61the examples need to be documented, tested and (most importantly)
62maintained.
63
64=item *
65
66The obsolete chat2 library that should never have been allowed
67to escape the laboratory has been decommissioned.
68
69=item *
70
71The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
72recognised but now cause fatal errors. The previous behaviour of
73ignoring them by default and warning if requested was unacceptable
74since it, in a way, falsely promised that the features could be used.
75
76=item *
77
78The (bogus) escape sequences \8 and \9 now give an optional warning
79("Unrecognized escape passed through"). There is no need to \-escape
80any C<\w> character.
81
82=item *
83
84lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
85In future releases this may become a fatal error.
86
87=item *
88
89The long deprecated uppercase aliases for the string comparison
90operators (EQ, NE, LT, LE, GE, GT) have now been removed.
91
92=item *
93
94The regular expression captured submatches ($1, $2, ...) are now
95more consistently unset if the match fails, instead of leaving false
96data lying around in them.
97
98=item *
99
100The tr///C and tr///U features have been removed and will not return;
101the interface was a mistake. Sorry about that. For similar
102functionality, see pack('U0', ...) and pack('C0', ...).
103
104=back
105
106=head1 Core Enhancements
107
108=over 4
109
110=item *
111
112C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
113in multiple arguments.)
114
115=item *
116
117my __PACKAGE__ now works.
118
119=item *
120
121C<no Module;> now works even if there is no "sub unimport" in the Module.
122
123=item *
124
125The numerical comparison operators return C<undef> if either operand
126is a NaN. Previously the behaviour was unspecified.
127
128=item *
129
130C<pack('U0a*', ...)> can now be used to force a string to UTF8.
131
132=item *
133
134prototype(\&) is now available.
135
136=item *
137
138There is now an UNTIE method.
139
140=back
141
142=head1 Modules and Pragmata
143
144=head2 New Modules
145
146=over 4
147
148=item *
149
150File::Temp allows one to create temporary files and directories in an
151easy, portable, and secure way.
152
153=item *
154
155Storable gives persistence to Perl data structures by allowing the
156storage and retrieval of Perl data to and from files in a fast and
157compact binary format.
158
159=back
160
161=head2 Updated And Improved Modules and Pragmata
162
163=over 4
164
165=item *
166
167The following independently supported modules have been updated to
168newer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
169the podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
170
171=item *
172
173Bug fixes and minor enhancements have been applied to B::Deparse,
174Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
175Math::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
176Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
177pragma.
178
179=item *
180
181The attributes::reftype() now works on tied arguments.
182
183=item *
184
185AutoLoader can now be disabled with C<no AutoLoader;>,
186
187=item *
188
189The English module can now be used without the infamous performance
190hit by saying
191
192 use English '-no_performance_hit';
193
194(Assuming, of course, that one doesn't need the troublesome variables
195C<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
196C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
197
198=item *
199
200File::Find now has pre- and post-processing callbacks. It also
201correctly changes directories when chasing symbolic links. Callbacks
202(naughtily) exiting with "next;" instead of "return;" now work.
203
204=item *
205
206File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
207prototype mismatch with CORE::glob().
208
209=item *
210
211IPC::Open3 now allows the use of numeric file descriptors.
212
213=item *
214
215use lib now works identically to @INC. Removing directories
216with 'no lib' now works.
217
218=item *
219
220C<%INC> now localised in a Safe compartment so that use/require work.
221
222=item *
223
224The Shell module now has an OO interface.
225
226=back
227
228=head1 Utility Changes
229
230=over 4
231
232=item *
233
234The Emacs perl mode (emacs/cperl-mode.el) has been updated to version
2354.31.
236
237=item *
238
239Perlbug is now much more robust. It also sends the bug report to
240perl.org, not perl.com.
241
242=item *
243
244The perlcc utility has been rewritten and its user interface (that is,
245command line) is much more like that of the UNIX C compiler, cc.
246
247=item *
248
249The xsubpp utility for extension writers now understands POD
250documentation embedded in the *.xs files.
251
252=back
253
254=head1 New Documentation
255
256=over 4
257
258=item *
259
260perl56delta details the changes between the 5.005 release and the
2615.6.0 release.
262
263=item *
264
265perldebtut is a Perl debugging tutorial.
266
267=item *
268
269perlebcdic contains considerations for running Perl on EBCDIC platforms.
270Note that unfortunately EBCDIC platforms that used to supported back in
271Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
272bring them back to the fold.
273
274=item *
275
276perlnewmod tells about writing and submitting a new module.
277
278=item *
279
280perlposix-bc explains using Perl on the POSIX-BC platform
281(an EBCDIC mainframe platform).
282
283=item *
284
285perlretut is a regular expression tutorial.
286
287=item *
288
289perlrequick is a regular expressions quick-start guide.
290Yes, much quicker than perlretut.
291
292=item *
293
294perlutil explains the command line utilities packaged with the Perl
295distribution.
296
297=back
298
299=head1 Performance Enhancements
300
301=over 4
302
303=item *
304
305map() that changes the size of the list should now work faster.
306
307=item *
308
309sort() has been changed to use mergesort internally as opposed to the
310earlier quicksort. For very small lists this may result in slightly
311slower sorting times, but in general the speedup should be at least
31220%. Additional bonuses are that the worst case behaviour of sort()
313is now better (in computer science terms it now runs in time O(N log N),
314as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
315and that sort() is now stable (meaning that elements with identical
316keys will stay ordered as they were before the sort).
317
318=back
319
320=head1 Installation and Configuration Improvements
321
322=head2 Generic Improvements
323
324=over 4
325
326=item *
327
328INSTALL now explains how you can configure Perl to use 64-bit
329integers even on non-64-bit platforms.
330
331=item *
332
333Policy.sh policy change: if you are reusing a Policy.sh file
334(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
335Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
336them will now be changed to the new prefix, /foo/bar. (Previously
337only $prefix changed.) If you do not like this new behaviour,
338specify prefix, siteprefix, and vendorprefix explicitly.
339
340=item *
341
342A new optional location for Perl libraries, otherlibdirs, is available.
343It can be used for example for vendor add-ons without disturbing Perl's
344own library directories.
345
346=item *
347
348In many platforms the vendor-supplied 'cc' is too stripped-down to
349build Perl (basically, 'cc' doesn't do ANSI C). If this seems
350to be the case and 'cc' does not seem to be the GNU C compiler
351'gcc', an automatic attempt is made to find and use 'gcc' instead.
352
353=item *
354
355gcc needs to closely track the operating system release to avoid
356build problems. If Configure finds that gcc was built for a different
357operating system release than is running, it now gives a clearly visible
358warning that there may be trouble ahead.
359
360=item *
361
362If binary compatibility with the 5.005 release is not wanted, Configure
363no longer suggests including the 5.005 modules in @INC.
364
365=item *
366
367Configure C<-S> can now run non-interactively.
368
369=item *
370
371configure.gnu now works with options with whitespace in them.
372
373=item *
374
375installperl now outputs everything to STDERR.
376
377=item *
378
379$Config{byteorder} is now computed dynamically (this is more robust
380with "fat binaries" where an executable image contains binaries for
381more than one binary platform.)
382
383=back
384
385=head1 Selected Bug Fixes
386
387=over 4
388
389=item *
390
391Several debugger fixes: exit code now reflects the script exit code,
392condition C<"0"> now treated correctly, the C<d> command now checks
393line number, the C<$.> no longer gets corrupted, all debugger output now
394goes correctly to the socket if RemotePort is set.
395
396=item *
397
398C<*foo{FORMAT}> now works.
399
400=item *
401
402Lexical warnings now propagating correctly between scopes.
403
404=item *
405
406Line renumbering with eval and C<#line> now works.
407
408=item *
409
410Fixed numerous memory leaks, especially in eval "".
411
412=item *
413
414Modulus of unsigned numbers now works (4063328477 % 65535 used to
415return 27406, instead of 27047).
416
417=item *
418
419Some "not a number" warnings introduced in 5.6.0 eliminated to be
420more compatible with 5.005. Infinity is now recognised as a number.
421
422=item *
423
424our() variables will not cause "will not stay shared" warnings.
425
426=item *
427
428pack "Z" now correctly terminates the string with "\0".
429
430=item *
431
432Fix password routines which in some shadow password platforms
433(e.g. HP-UX) caused getpwent() to return every other entry.
434
435=item *
436
437printf() no longer resets the numeric locale to "C".
438
439=item *
440
441C<q(a\\b)> now parses correctly as C<'a\\b'>.
442
443=item *
444
445Printing quads (64-bit integers) with printf/sprintf now works
446without the q L ll prefixes (assuming you are on a quad-capable platform).
447
448=item *
449
450Regular expressions on references and overloaded scalars now work.
451
452=item *
453
454scalar() now forces scalar context even when used in void context.
455
456=item *
457
458sort() arguments are now compiled in the right wantarray context
459(they were accidentally using the context of the sort() itself).
460
461=item *
462
463Changed the POSIX character class C<[[:space:]]> to include the (very
464rare) vertical tab character. Added a new POSIX-ish character class
465C<[[:blank:]]> which stands for horizontal whitespace (currently,
466the space and the tab).
467
468=item *
469
470$AUTOLOAD, sort(), lock(), and spawning subprocesses
471in multiple threads simultaneously are now thread-safe.
472
473=item *
474
475Allow read-only string on left hand side of non-modifying tr///.
476
477=item *
478
479Several Unicode fixes (but still not perfect).
480
481=over 8
482
483=item *
484
485BOMs (byte order marks) in the beginning of Perl files
486(scripts, modules) should now be transparently skipped.
487UTF-16 (UCS-2) encoded Perl files should now be read correctly.
488
489=item *
490
491The character tables have been updated to Unicode 3.0.1.
492
493=item *
494
495chr() for values greater than 127 now create utf8 when under use
496utf8.
497
498=item *
499
500Comparing with utf8 data does not magically upgrade non-utf8 data into
501utf8.
502
503=item *
504
505C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
506
507=item *
508
509Concatenation with the C<.> operator or via variable interpolation,
510C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
511substitution with C<s///>, single-quoted UTF8, should now work--in
512theory.
513
514=item *
515
516The C<tr///> operator now works I<slightly> better but is still rather
517broken. Note that the C<tr///CU> functionality has been removed (but
518see pack('U0', ...)).
519
520=item *
521
522vec() now refuses to deal with characters >255.
523
524=item *
525
526Zero entries were missing from the Unicode classes like C<IsDigit>.
527
528=back
529
530=item *
531
532UNIVERSAL::isa no longer caches methods incorrectly. (This broke
533the Tk extension with 5.6.0.)
534
535=back
536
537=head2 Platform Specific Changes and Fixes
538
539=over 4
540
541=item *
542
543BSDI 4.*
544
545Perl now works on post-4.0 BSD/OSes.
546
547=item *
548
549All BSDs
550
551Setting C<$0> now works (as much as possible; see perlvar for details).
552
553=item *
554
555Cygwin
556
557Numerous updates; currently synchronised with Cygwin 1.1.4.
558
559=item *
560
561EPOC
562
563EPOC update after Perl 5.6.0. See README.epoc.
564
565=item *
566
567FreeBSD 3.*
568
569Perl now works on post-3.0 FreeBSDs.
570
571=item *
572
573HP-UX
574
575README.hpux updated; C<Configure -Duse64bitall> now almost works.
576
577=item *
578
579IRIX
580
581Numerous compilation flag and hint enhancements; accidental mixing
582of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
583
584=item *
585
586Linux
587
588Long doubles should now work (see INSTALL).
589
590=item *
591
592MacOS Classic
593
594Compilation of the standard Perl distribution in MacOS Classic should
595now work if you have the Metrowerks development environment and
596the missing Mac-specific toolkit bits. Contact the macperl mailing
597list for details.
598
599=item *
600
601MPE/iX
602
603MPE/iX update after Perl 5.6.0. See README.mpeix.
604
605=item *
606
607NetBSD/sparc
608
609Perl now works on NetBSD/sparc.
610
611=item *
612
613OS/2
614
615Now works with usethreads (see INSTALL).
616
617=item *
618
619Solaris
620
62164-bitness using the Sun Workshop compiler now works.
622
623=item *
624
625Tru64 (aka Digital UNIX, aka DEC OSF/1)
626
627The operating system version letter now recorded in $Config{osvers}.
628Allow compiling with gcc (previously explicitly forbidden). Compiling
629with gcc still not recommended because buggy code results, even with
630gcc 2.95.2.
631
632=item *
633
634Unicos
635
636Fixed various alignment problems that lead into core dumps either
637during build or later; no longer dies on math errors at runtime;
638now using full quad integers (64 bits), previously was using
639only 46 bit integers for speed.
640
641=item *
642
643VMS
644
645chdir() now works better despite a CRT bug; now works with MULTIPLICITY
646(see INSTALL); now works with Perl's malloc.
647
648=item *
649
650Windows
651
652=over 8
653
654=item *
655
656accept() no longer leaks memory.
657
658=item *
659
660Better chdir() return value for a non-existent directory.
661
662=item *
663
664New %ENV entries now propagate to subprocesses.
665
666=item *
667
668$ENV{LIB} now used to search for libs under Visual C.
669
670=item *
671
672A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
673
674=item *
675
676Allow REG_EXPAND_SZ keys in the registry.
677
678=item *
679
680Can now send() from all threads, not just the first one.
681
682=item *
683
684Fake signal handling reenabled, bugs and all.
685
686=item *
687
688Less stack reserved per thread so that more threads can run
689concurrently. (Still 16M per thread.)
690
691=item *
692
693C<File::Spec->tmpdir()> now prefers C:/temp over /tmp
694(works better when perl is running as service).
695
696=item *
697
698Better UNC path handling under ithreads.
699
700=item *
701
702wait() and waitpid() now work much better.
703
704=item *
705
706winsock handle leak fixed.
707
708=back
709
710=back
711
712=head1 New or Changed Diagnostics
713
714All regular expression compilation error messages are now hopefully
715easier to understand both because the error message now comes before
716the failed regex and because the point of failure is now clearly
717marked.
718
719The various "opened only for", "on closed", "never opened" warnings
720drop the C<main::> prefix for filehandles in the C<main> package,
721for example C<STDIN> instead of <main::STDIN>.
722
723The "Unrecognized escape" warning has been extended to include C<\8>,
724C<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
725
726=head1 Changed Internals
727
728=over 4
729
730=item *
731
732perlapi.pod (a companion to perlguts) now attempts to document the
733internal API.
734
735=item *
736
737You can now build a really minimal perl called microperl.
738Building microperl does not require even running Configure;
739C<make -f Makefile.micro> should be enough. Beware: microperl makes
740many assumptions, some of which may be too bold; the resulting
741executable may crash or otherwise misbehave in wondrous ways.
742For careful hackers only.
743
744=item *
745
746Added rsignal(), whichsig(), do_join() to the publicised API.
747
748=item *
749
750Made possible to propagate customised exceptions via croak()ing.
751
752=item *
753
754Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
755
756=item *
757
758Now xsubs can have attributes just like subs.
759
760=back
761
762=head1 Known Problems
763
764=head2 Unicode Support Still Far From Perfect
765
766We're working on it. Stay tuned.
767
768=head2 EBCDIC Still A Lost Platform
769
770The plan is to bring them back.
771
772=head2 Building Extensions Can Fail Because Of Largefiles
773
774Certain extensions like mod_perl and BSD::Resource are known to have
775issues with `largefiles', a change brought by Perl 5.6.0 in which file
776offsets default to 64 bits wide, where supported. Modules may fail to
777compile at all or compile and work incorrectly. Currently there is no
778good solution for the problem, but Configure now provides appropriate
779non-largefile ccflags, ldflags, libswanted, and libs in the %Config
780hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
781having problems can try configuring themselves without the
782largefileness. This is admittedly not a clean solution, and the
783solution may not even work at all. One potential failure is whether
784one can (or, if one can, whether it's a good idea) link together at
785all binaries with different ideas about file offsets, all this is
786platform-dependent.
787
788=head2 ftmp-security tests warn 'system possibly insecure'
789
790Don't panic. Read INSTALL 'make test' section instead.
791
792=head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
793
794If perl is configured with -Duse64bitall, the successful result of the
795subtest 10 of lib/posix may arrive before the successful result of the
796subtest 9, which confuses the test harness so much that it thinks the
797subtest 9 failed.
798
799=head2 Long Doubles Still Don't Work In Solaris
800
801The experimental long double support is still very much so in Solaris.
802(Other platforms like Linux and Tru64 are beginning to solidify in
803this area.)
804
805=head2 Linux With Sfio Fails op/misc Test 48
806
807No known fix.
808
809=head2 Storable tests fail in some platforms
810
811If any Storable tests fail the use of Storable is not advisable.
812
813=over 4
814
815=item *
816
817Many Storable tests fail on AIX configured with 64 bit integers.
818
819So far unidentified problems break Storable in AIX if Perl is
820configured to use 64 bit integers. AIX in 32-bit mode works and
821other 64-bit platforms work with Storable.
822
823=item *
824
825DOS DJGPP may hang when testing Storable.
826
827=item *
828
829st-06compat fails in UNICOS and UNICOS/mk.
830
831This means that you cannot read old (pre-Storable-0.7) Storable images
832made in other platforms.
833
834=item *
835
836st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
837
838=back
839
840=head2 Threads Are Still Experimental
841
842Multithreading is still an experimental feature. Some platforms
843emit the following message for lib/thr5005
844
845 #
846 # This is a KNOWN FAILURE, and one of the reasons why threading
847 # is still an experimental feature. It is here to stop people
848 # from deploying threads in production. ;-)
849 #
850
851and another known thread-related warning is
852
853 pragma/overload......Unbalanced saves: 3 more saves than restores
854 panic: magic_mutexfree during global destruction.
855 ok
856 lib/selfloader.......Unbalanced saves: 3 more saves than restores
857 panic: magic_mutexfree during global destruction.
858 ok
859 lib/st-dclone........Unbalanced saves: 3 more saves than restores
860 panic: magic_mutexfree during global destruction.
861 ok
862
863=head2 The Compiler Suite Is Still Experimental
864
865The compiler suite is slowly getting better but is nowhere near
866working order yet. The backend part that has seen perhaps the most
867progress is the bytecode compiler.
868
869=head1 Reporting Bugs
870
871If you find what you think is a bug, you might check the articles
872recently posted to the comp.lang.perl.misc newsgroup and the perl
873bug database at http://bugs.perl.org. There may also be
874information at http://www.perl.com/perl/, the Perl Home Page.
875
876If you believe you have an unreported bug, please run the B<perlbug>
877program included with your release. Be sure to trim your bug down
878to a tiny but sufficient test case. Your bug report, along with the
879output of C<perl -V>, will be sent off to perlbug@perl.org to be
880analysed by the Perl porting team.
881
882=head1 SEE ALSO
883
884The F<Changes> file for exhaustive details on what changed.
885
886The F<INSTALL> file for how to build Perl.
887
888The F<README> file for general stuff.
889
890The F<Artistic> and F<Copying> files for copyright information.
891
892=head1 HISTORY
893
894Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
895from The Perl Porters and Perl Users submitting feedback and patches.
896
897Send omissions or corrections to <F<perlbug@perl.org>>.
898
899=cut