3 perl571delta - what's new for perl v5.7.1
7 This document describes differences between the 5.7.0 release and the
10 (To view the differences between the 5.6.0 release and the 5.7.0
11 release, see L<perl570delta>).
13 =head1 Security Vulnerability Closed
15 (This change was already made in 5.7.0 but bears repeating here.)
17 A potential security vulnerability in the optional suidperl component
18 of Perl was identified in August 2000. suidperl is neither built nor
19 installed by default. As of April 2001 the only known vulnerable
20 platform is Linux, most likely all Linux distributions. CERT and
21 various vendors and distributors have been alerted about the vulnerability.
22 See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
25 The problem was caused by Perl trying to report a suspected security
26 exploit attempt using an external program, /bin/mail. On Linux
27 platforms the /bin/mail program had an undocumented feature which
28 when combined with suidperl gave access to a root shell, resulting in
29 a serious compromise instead of reporting the exploit attempt. If you
30 don't have /bin/mail, or if you have 'safe setuid scripts', or if
31 suidperl is not installed, you are safe.
33 The exploit attempt reporting feature has been completely removed from
34 all the Perl 5.7 releases (and will be gone also from the maintenance
35 release 5.6.1), so that particular vulnerability isn't there anymore.
36 However, further security vulnerabilities are, unfortunately, always
37 possible. The suidperl code is being reviewed and if deemed too risky
38 to continue to be supported, it may be completely removed from future
39 releases. In any case, suidperl should only be used by security
40 experts who know exactly what they are doing and why they are using
41 suidperl instead of some other solution such as sudo (see
42 http://www.courtesan.com/sudo/).
44 =head1 Incompatible Changes
50 Although "you shouldn't do that", it was possible to write code that
51 depends on Perl's hashed key order (Data::Dumper does this). The new
52 algorithm "One-at-a-Time" produces a different hashed key order.
53 More details are in L</"Performance Enhancements">.
57 The list of filenames from glob() (or <...>) is now by default sorted
58 alphabetically to be csh-compliant. (bsd_glob() does still sort platform
59 natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
63 =head1 Core Enhancements
69 AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
70 to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
74 IO is now by default done via PerlIO rather than system's "stdio".
75 PerlIO allows "layers" to be "pushed" onto a file handle to alter the
76 handle's behaviour. Layers can be specified at open time via 3-arg
79 open($fh,'>:crlf :utf8', $path) || ...
81 or on already opened handles via extended C<binmode>:
83 binmode($fh,':encoding(iso-8859-7)');
85 The built-in layers are: unix (low level read/write), stdio (as in
86 previous Perls), perlio (re-implementation of stdio buffering in a
87 portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
88 but available on any platform). A mmap layer may be available if
89 platform supports it (mostly UNIXes).
91 Layers to be applied by default may be specified via the 'open' pragma.
93 See L</"Installation and Configuration Improvements"> for the effects
94 of PerlIO on your architecture name.
98 File handles can be marked as accepting Perl's internal encoding of Unicode
99 (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
101 open($fh,">:utf8","Uni.txt");
103 Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
104 for you since it's not UTF-8 what you will be getting but instead
105 UTF-EBCDIC. See L<perlunicode>, L<utf8>, and
106 http://www.unicode.org/unicode/reports/tr16/ for more information.
107 In future releases this naming may change.
111 File handles can translate character encodings from/to Perl's internal
112 Unicode form on read/write via the ":encoding()" layer.
116 File handles can be opened to "in memory" files held in Perl scalars via:
118 open($fh,'>', \$variable) || ...
122 Anonymous temporary files are available without need to
123 'use FileHandle' or other module via
125 open($fh,"+>", undef) || ...
127 That is a literal undef, not an undefined value.
131 The list form of C<open> is now implemented for pipes (at least on UNIX):
133 open($fh,"-|", 'cat', '/etc/motd')
135 creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
140 The following builtin functions are now overridable: chop(), chomp(),
141 each(), keys(), pop(), push(), shift(), splice(), unshift().
145 Formats now support zero-padded decimal fields.
149 Perl now tries internally to use integer values in numeric conversions
150 and basic arithmetics (+ - * /) if the arguments are integers, and
151 tries also to keep the results stored internally as integers.
152 This change leads into often slightly faster and always less lossy
153 arithmetics. (Previously Perl always preferred floating point numbers
158 The printf() and sprintf() now support parameter reordering using the
159 C<%\d+\$> and C<*\d+\$> syntaxes. For example
161 print "%2\$s %1\$s\n", "foo", "bar";
163 will print "bar foo\n"; This feature helps in writing
164 internationalised software.
168 Unicode in general should be now much more usable. Unicode can be
169 used in hash keys, Unicode in regular expressions should work now,
170 Unicode in tr/// should work now (though tr/// seems to be a
171 particularly tricky to get right, so you have been warned)
175 The Unicode Character Database coming with Perl has been upgraded
176 to Unicode 3.1. For more information, see http://www.unicode.org/,
177 and http://www.unicode.org/unicode/reports/tr27/
179 For developers interested in enhancing Perl's Unicode capabilities:
180 almost all the UCD files are included with the Perl distribution in
181 the lib/unicode subdirectory. The most notable omission, for space
182 considerations, is the Unihan database.
186 The Unicode character classes \p{Blank} and \p{SpacePerl} have been
187 added. "Blank" is like C isblank(), that is, it contains only
188 "horizontal whitespace" (the space character is, the newline isn't),
189 and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
190 isn't, since that includes the vertical tabulator character, whereas
195 =head1 Modules and Pragmata
203 B::Concise, by Stephen McCamant, is a new compiler backend for
204 walking the Perl syntax tree, printing concise info about ops.
205 The output is highly customisable.
207 See L<B::Concise> for more information.
211 Class::ISA, by Sean Burke, for reporting the search path for a
212 class's ISA tree, has been added.
214 See L<Class::ISA> for more information.
218 Cwd has now a split personality: if possible, an extension is used,
219 (this will hopefully be both faster and more secure and robust) but
220 if not possible, the familiar Perl library implementation is used.
224 Digest, a frontend module for calculating digests (checksums),
225 from Gisle Aas, has been added.
227 See L<Digest> for more information.
231 Digest::MD5 for calculating MD5 digests (checksums), by Gisle Aas,
234 use Digest::MD5 'md5_hex';
236 $digest = md5_hex("Thirsty Camel");
238 print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
240 NOTE: the MD5 backward compatibility module is deliberately not
241 included since its use is discouraged.
243 See L<Digest::MD5> for more information.
247 Encode, by Nick Ing-Simmons, provides a mechanism to translate
248 between different character encodings. Support for Unicode,
249 ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
250 compiled in to the module. Several other encodings (like Japanese,
251 Chinese, and MacIntosh encodings) are included and will be loaded at
254 Any encoding supported by Encode module is also available to the
255 ":encoding()" layer if PerlIO is used.
257 See L<Encode> for more information.
261 Filter::Simple is an easy-to-use frontend to Filter::Util::Call,
268 use Filter::Simple sub {
269 while (my ($from, $to) = splice @_, 0, 2) {
278 use MyFilter qr/red/ => 'green';
280 print "red\n"; # this code is filtered, will print "green\n"
281 print "bored\n"; # this code is filtered, will print "bogreen\n"
285 print "red\n"; # this code is not filtered, will print "red\n"
287 See L<Filter::Simple> for more information.
291 Filter::Util::Call, by Paul Marquess, provides you with the
292 framework to write I<Source Filters> in Perl. For most uses
293 the frontend Filter::Simple is to be preferred.
294 See L<Filter::Util::Call> for more information.
298 Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language,
299 from Neil Bowers, have been added. They provide the codes for various
300 locale standards, such as "fr" for France, "usd" for US Dollar, and
305 $country = code2country('jp'); # $country gets 'Japan'
306 $code = country2code('Norway'); # $code gets 'no'
308 See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
309 and L<Locale::Language> for more information.
313 MIME::Base64, by Gisle Aas, allows you to encode data in base64.
317 $encoded = encode_base64('Aladdin:open sesame');
318 $decoded = decode_base64($encoded);
320 print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
322 See L<MIME::Base64> for more information.
326 MIME::QuotedPrint, by Gisle Aas, allows you to encode data in
327 quoted-printable encoding.
329 use MIME::QuotedPrint;
331 $encoded = encode_qp("Smiley in Unicode: \x{263a}");
332 $decoded = decode_qp($encoded);
334 print $encoded, "\n"; # "Smiley in Unicode: =263A"
336 MIME::QuotedPrint has been enhanced to provide the basic methods
337 necessary to use it with PerlIO::Via as in :
339 use MIME::QuotedPrint;
340 open($fh,">Via(MIME::QuotedPrint)",$path)
342 See L<MIME::QuotedPrint> for more information.
346 PerlIO::Scalar, by Nick Ing-Simmons, provides the implementation of
347 IO to "in memory" Perl scalars as discussed above. It also serves as
348 an example of a loadable layer. Other future possibilities include
349 PerlIO::Array and PerlIO::Code. See L<PerlIO::Scalar> for more
354 PerlIO::Via, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
355 PerlIO layer functionality provided by a class (typically implemented
358 use MIME::QuotedPrint;
359 open($fh,">Via(MIME::QuotedPrint)",$path)
361 This will automatically convert everything output to C<$fh>
362 to Quoted-Printable. See L<PerlIO::Via> for more information.
366 Pod::Text::Overstrike, by Joe Smith, has been added.
367 It converts POD data to formatted overstrike text.
368 See L<Pod::Text::Overstrike> for more information.
372 Switch from Damian Conway has been added. Just by saying
376 you have C<switch> and C<case> available in Perl.
382 case 1 { print "number 1" }
383 case "a" { print "string a" }
384 case [1..10,42] { print "number in list" }
385 case (@array) { print "number in list" }
386 case /\w+/ { print "pattern" }
387 case qr/\w+/ { print "pattern" }
388 case (%hash) { print "entry in hash" }
389 case (\%hash) { print "entry in hash" }
390 case (\&sub) { print "arg to subroutine" }
391 else { print "previous case not true" }
394 See L<Switch> for more information.
398 Text::Balanced from Damian Conway has been added, for
399 extracting delimited text sequences from strings.
401 use Text::Balanced 'extract_delimited';
403 ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
405 $a will be "'never say never'", $b will be ', he never said'.
407 In addition to extract_delimited() there are also extract_bracketed(),
408 extract_quotelike(), extract_codeblock(), extract_variable(),
409 extract_tagged(), extract_multiple(), gen_delimited_pat(), and
410 gen_extract_tagged(). With these you can implement rather advanced
411 parsing algorithms. See L<Text::Balanced> for more information.
415 Tie::RefHash::Nestable, by Edward Avis, allows storing hash references
416 (unlike the standard Tie::Refhash) The module is contained within
421 XS::Typemap, by Tim Jenness, is a test extension that exercises XS
422 typemaps. Nothing gets installed but for extension writers the code
427 =head2 Updated And Improved Modules and Pragmata
433 B::Deparse should be now more robust. It still far from providing a full
434 round trip for any random piece of Perl code, though, and is under active
435 development: expect more robustness in 5.7.2.
439 Class::Struct can now define the classes in compile time.
443 Math::BigFloat has undergone much fixing, and in addition the fmod()
444 function now supports modulus operations.
446 (The fixed Math::BigFloat module is also available in CPAN for those
447 who can't upgrade their Perl: http://www.cpan.org/authors/id/J/JP/JPEACOCK/)
451 Devel::Peek now has an interface for the Perl memory statistics
452 (this works only if you are using perl's malloc, and if you have
453 compiled with debugging).
457 IO::Socket has now atmark() method, which returns true if the socket
458 is positioned at the out-of-band mark. The method is also exportable
459 as a sockatmark() function.
463 IO::Socket::INET has support for ReusePort option (if your platform
464 supports it). The Reuse option now has an alias, ReuseAddr. For clarity
465 you may want to prefer ReuseAddr.
469 Net::Ping has been enhanced. There is now "external" protocol which
470 uses Net::Ping::External module which runs external ping(1) and parses
471 the output. An alpha version of Net::Ping::External is available in
472 CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
476 The C<open> pragma allows layers other than ":raw" and ":crlf" when
481 POSIX::sigaction() is now much more flexible and robust.
482 You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
483 handlers, installing new handlers was not atomic.
487 The Test module has been significantly enhanced. Its use is
488 greatly recommended for module writers.
492 The utf8:: name space (as in the pragma) provides various
493 Perl-callable functions to provide low level access to Perl's
494 internal Unicode representation. At the moment only length()
495 has been implemented.
499 The following modules have been upgraded from the versions at CPAN:
500 CPAN, CGI, DB_File, File::Temp, Getopt::Long, Pod::Man, Pod::Text,
501 Storable, Text-Tabs+Wrap.
503 =head1 Performance Enhancements
509 Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
510 (http://burtleburtle.net/bob/hash/doobs.html). This algorithm is
511 reasonably fast while producing a much better spread of values than
512 the old hashing algorithm (originally by Chris Torek, later tweaked by
513 Ilya Zakharevich). Hash values output from the algorithm on a hash of
514 all 3-char printable ASCII keys comes much closer to passing the
515 DIEHARD random number generation tests. According to perlbench, this
516 change has not affected the overall speed of Perl.
520 unshift() should now be noticeably faster.
524 =head1 Utility Changes
530 h2xs now produces template README.
534 s2p has been completely rewritten in Perl. (It is in fact a full
535 implementation of sed in Perl.)
539 xsubpp now supports OUT keyword.
543 =head1 New Documentation
547 Internal replacements for standard C library functions.
548 (Interesting only for extension writers and Perl core hackers.)
552 Internals of PerlIO with layers.
556 Documentation on compiling Perl on AIX has been added. AIX has
557 several different C compilers and getting the right patch level
558 is essential. On install README.aix will be installed as L<perlaix>.
562 Documentation on compiling Perl on the POSIX-BC platform (an EBCDIC
563 mainframe environment) has been added.
565 This was formerly known as README.posix-bc but the name was considered
566 to be too confusing (it has nothing to do with the POSIX module or the
567 POSIX standard). On install README.bs2000 will be installed as L<perlbs2000>.
571 In perl 5.7.1 (and in the 5.6.1) the MacPerl sources have been
572 synchronised with the standard Perl sources. To compile MacPerl
573 some additional steps are required, and this file documents those
574 steps. On install README.macos will be installed as L<perlmacos>.
578 The README.mpeix has been podified, which means that this information
579 about compiling and using Perl on the MPE/iX miniframe platform will
580 be installed as L<perlmpeix>.
582 =head2 README.solaris
584 README.solaris has been created and Solaris wisdom from elsewhere
585 in the Perl documentation has been collected there. On install
586 README.solaris will be installed as L<perlsolaris>.
590 The README.vos has been podified, which means that this information
591 about compiling and using Perl on the Stratus VOS miniframe platform
592 will be installed as L<perlvos>.
594 =head2 Porting/repository.pod
596 Documentation on how to use the Perl source repository has been added.
598 =head1 Installation and Configuration Improvements
604 Because PerlIO is now the default on most platforms, "-perlio" doesn't
605 get appended to the $Config{archname} (also known as $^O) anymore.
606 Instead, if you explicitly choose not to use perlio (Configure command
607 line option -Uuseperlio), you will get "-stdio" appended.
611 Another change related to the architecture name is that "-64all"
612 (-Duse64bitall, or "maximally 64-bit") is appended only if your
613 pointers are 64 bits wide. (To be exact, the use64bitall is ignored.)
617 APPLLIB_EXP, a less-know configuration-time definition, has been
618 documented. It can be used to prepend site-specific directories
619 to Perl's default search path (@INC), see INSTALL for information.
623 Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
624 has been documented in INSTALL.
628 If you are on IRIX or Tru64 platforms, new profiling/debugging options
629 have been added, see L<perlhack> for more information about pixie and
634 =head2 New Or Improved Platforms
636 For the list of platforms known to support Perl,
637 see L<perlport/"Supported Platforms">.
643 AIX dynamic loading should be now better supported.
647 After a long pause, AmigaOS has been verified to be happy with Perl.
651 EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
652 have been regained. Many test suite tests still fail and the
653 co-existence of Unicode and EBCDIC isn't quite settled, but the
654 situation is much better than with Perl 5.6. See L<perlos390>,
655 L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
659 Building perl with -Duseithreads or -Duse5005threads now works under
660 HP-UX 10.20 (previously it only worked under 10.30 or later). You will
661 need a thread library package installed. See README.hpux.
665 MacOS Classic (MacPerl has of course been available since
666 perl 5.004 but now the source code bases of standard Perl
667 and MacPerl have been synchronised)
671 NCR MP-RAS is now supported.
675 NonStop-UX is now supported.
679 Amdahl UTS is now supported.
683 z/OS (formerly known as OS/390, formerly known as MVS OE) has now
684 support for dynamic loading. This is not selected by default,
685 however, you must specify -Dusedl in the arguments of Configure.
689 =head2 Generic Improvements
695 Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
696 when building the Perl binary. The only exception to this is SunOS 4.x,
701 Some new Configure symbols, useful for extension writers:
709 =item d_fcntl_can_lock
711 Whether fcntl() can be used for file locking.
719 For getpagesize(), though you should prefer POSIX::sysconf(_SC_PAGE_SIZE))
727 Whether one needs to use Perl_va_copy() to copy varargs.
737 The number of elements in an array needed to hold all the available signals.
745 Whether one needs to access character data aligned by U32 sized pointers.
755 Removed Configure symbols: the PDP-11 memory model settings: huge,
756 large, medium, models.
760 SOCKS support is now much more robust.
764 If your file system supports symbolic links you can build Perl outside
765 of the source directory by
767 mkdir /tmp/perl/build/directory
768 cd /tmp/perl/build/directory
769 sh /path/to/perl/source/Configure -Dmksymlinks ...
771 This will create in /tmp/perl/build/directory a tree of symbolic links
772 pointing to files in /path/to/perl/source. The original files are left
773 unaffected. After Configure has finished you can just say
777 and Perl will be built and tested, all in /tmp/perl/build/directory.
781 =head1 Selected Bug Fixes
783 Numerous memory leaks and uninitialized memory accesses have been hunted down.
784 Most importantly anonymous subs used to leak quite a bit.
790 chop(@list) in list context returned the characters chopped in
791 reverse order. This has been reversed to be in the right order.
795 The order of DESTROYs has been made more predictable.
799 mkdir() now ignores trailing slashes in the directory name,
800 as mandated by POSIX.
804 Attributes (like :shared) didn't work with our().
808 The PERL5OPT environment variable (for passing command line arguments
809 to Perl) didn't work for more than a single group of options.
813 The tainting behaviour of sprintf() has been rationalized. It does
814 not taint the result of floating point formats anymore, making the
815 behaviour consistent with that of string interpolation.
819 All but the first argument of the IO syswrite() method are now optional.
823 Tie::ARRAY SPLICE method was broken.
827 vec() now tries to work with characters <= 255 when possible, but it leaves
828 higher character values in place. In that case, if vec() was used to modify
829 the string, it is no longer considered to be utf8-encoded.
833 =head2 Platform Specific Changes and Fixes
839 Linux previously had problems related to sockaddrlen when using
840 accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
844 Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
854 Borland C++ v5.5 is now a supported compiler that can build Perl.
855 However, the generated binaries continue to be incompatible with those
856 generated by the other supported compilers (GCC and Visual C++).
860 Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
861 Other bugs in chdir() and Cwd::cwd() have also been fixed.
865 Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
869 HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
873 The makefiles now provide a single switch to bulk-enable all the features
874 enabled in ActiveState ActivePerl (a popular binary distribution).
880 =head1 New or Changed Diagnostics
882 Two new debugging options have been added: if you have compiled your
883 Perl with debugging, you can use the -DT and -DR options to trace
884 tokenising and to add reference counts to displaying variables,
891 If an attempt to use a (non-blessed) reference as an array index
892 is made, a warning is given.
896 C<push @a;> and C<unshift @a;> (with no values to push or unshift)
897 now give a warning. This may be a problem for generated and evaled
902 =head1 Changed Internals
908 Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
909 For the full list of the available APIs see L<perlapi>.
913 dTHR and djSP have been obsoleted; the former removed (because it's
914 a no-op) and the latter replaced with dSP.
918 Perl now uses system malloc instead of Perl malloc on all 64-bit
919 platforms, and even in some not-always-64-bit platforms like AIX,
920 IRIX, and Solaris. This change breaks backward compatibility but
921 Perl's malloc has problems with large address spaces and also the
922 speed of vendors' malloc is generally better in large address space
923 machines (Perl's malloc is mostly tuned for space).
929 Many new tests have been added. The most notable is probably the
930 lib/1_compile: it is very notable because running it takes quite a
931 long time -- it test compiles all the Perl modules in the distribution.
934 =head1 Known Problems
936 Note that unlike other sections in this document (which describe
937 changes since 5.7.0) this section is cumulative containing known
938 problems for all the 5.7 releases.
940 =head2 AIX vac 5.0.0.0 May Produce Buggy Code For Perl
942 The AIX C compiler vac version 5.0.0.0 may produce buggy code,
943 resulting in few random tests failing, but when the failing tests
944 are run by hand, they succeed. We suggest upgrading to at least
945 vac version 5.0.1.0, that has been known to compile Perl correctly.
946 "lslpp -L|grep vac.C" will tell you the vac version.
948 =head2 lib/ftmp-security tests warn 'system possibly insecure'
950 Don't panic. Read INSTALL 'make test' section instead.
952 =head2 lib/io_multihomed Fails In LP64-Configured HP-UX
954 The lib/io_multihomed test may hang in HP-UX if Perl has been
955 configured to be 64-bit. Because other 64-bit platforms do not hang in
956 this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
957 test attempts to create and connect to "multihomed" sockets (sockets
958 which have multiple IP addresses).
960 =head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
962 If perl is configured with -Duse64bitall, the successful result of the
963 subtest 10 of lib/posix may arrive before the successful result of the
964 subtest 9, which confuses the test harness so much that it thinks the
969 The test fails on various platforms (PA64 and IA64 are known), but the
970 exact cause is still being investigated.
972 =head2 Linux With Sfio Fails op/misc Test 48
976 =head2 sigaction test 13 in VMS
978 The test is known to fail; whether it's because of VMS of because
979 of faulty test is not known.
981 =head2 sprintf tests 129 and 130
983 The op/sprintf tests 129 and 130 are known to fail on some platforms.
984 Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
985 The failing platforms do not comply with the ANSI C Standard, line
986 19ff on page 134 of ANSI X3.159 1989 to be exact. (They produce
987 something else than "1" and "-1" when formatting 0.6 and -0.6 using
988 the printf format "%.0f", most often they produce "0" and "-0".)
990 =head2 Failure of Thread tests
992 The subtests 19 and 20 of lib/thr5005.t test are known to fail due to
993 fundamental problems in the 5.005 threading implementation. These are
994 not new failures--Perl 5.005_0x has the same bugs, but didn't have
995 these tests. (Note that support for 5.005-style threading remains
998 =head2 Localising a Tied Variable Leaks Memory
1001 tie my %tie_hash => 'Tie::StdHash';
1005 local($tie_hash{Foo}) = 1; # leaks
1007 Code like the above is known to leak memory every time the local()
1010 =head2 Self-tying of Arrays and Hashes Is Forbidden
1012 Self-tying of arrays and hashes is broken in rather deep and
1013 hard-to-fix ways. As a stop-gap measure to avoid people from getting
1014 frustrated at the mysterious results (core dumps, most often) it is
1015 for now forbidden (you will get a fatal error even from an attempt).
1017 =head2 Building Extensions Can Fail Because Of Largefiles
1019 Some extensions like mod_perl are known to have issues with
1020 `largefiles', a change brought by Perl 5.6.0 in which file offsets
1021 default to 64 bits wide, where supported. Modules may fail to compile
1022 at all or compile and work incorrectly. Currently there is no good
1023 solution for the problem, but Configure now provides appropriate
1024 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
1025 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
1026 having problems can try configuring themselves without the
1027 largefileness. This is admittedly not a clean solution, and the
1028 solution may not even work at all. One potential failure is whether
1029 one can (or, if one can, whether it's a good idea) link together at
1030 all binaries with different ideas about file offsets, all this is
1033 =head2 The Compiler Suite Is Still Experimental
1035 The compiler suite is slowly getting better but is nowhere near
1038 =head1 Reporting Bugs
1040 If you find what you think is a bug, you might check the articles
1041 recently posted to the comp.lang.perl.misc newsgroup and the perl
1042 bug database at http://bugs.perl.org. There may also be
1043 information at http://www.perl.com/perl/, the Perl Home Page.
1045 If you believe you have an unreported bug, please run the B<perlbug>
1046 program included with your release. Be sure to trim your bug down
1047 to a tiny but sufficient test case. Your bug report, along with the
1048 output of C<perl -V>, will be sent off to perlbug@perl.org to be
1049 analysed by the Perl porting team.
1053 The F<Changes> file for exhaustive details on what changed.
1055 The F<INSTALL> file for how to build Perl.
1057 The F<README> file for general stuff.
1059 The F<Artistic> and F<Copying> files for copyright information.
1063 Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
1064 from The Perl Porters and Perl Users submitting feedback and patches.
1066 Send omissions or corrections to <F<perlbug@perl.org>>.