=head1 Incompatible Changes
+=head2 Hash Randomisation
+
+Mainly due to security reasons, the "random ordering" of hashes
+has been made even more random. Previously while the order of hash
+elements from keys(), values(), and each() was essentially random,
+it was still repeatable. Now, however, the order varies between
+different runs of Perl.
+
+B<Perl has never guaranteed any ordering of the hash keys>, and the
+ordering has already changed several times during the lifetime of
+Perl 5. Also, the ordering of hash keys has always been, and
+continues to be, affected by the insertion order.
+
+The added randomness may affect applications.
+
+One possible scenario is when output of an application has included
+hash data. For example, if you have used the Data::Dumper module to
+dump data into different files, and then compared the files to see
+whether the data has changed, now you will have false positives since
+the order in which hashes are dumped will vary. In general the cure
+is to sort the keys (or the values); in particular for Data::Dumper to
+use the C<Sortkeys> option. If some particular order is really
+important, use tied hashes: for example the Tie::IxHash module
+which by default preserves the order in which the hash elements
+were added.
+
+More subtle problem is reliance on the order of "global destruction".
+That is what happens at the end of execution: Perl destroys all data
+structures, including user data. If your destructors (the DESTROY
+subroutines) have assumed any particular ordering to the global
+destruction, there might be problems ahead. For example, in a
+destructor of one object you cannot assume that objects of any other
+class are still available, unless you hold a reference to them.
+If the environment variable PERL_DESTRUCT_LEVEL is set to a non-zero
+value, or if Perl is exiting a spawned thread, it will also destruct
+the ordinary references and the symbol tables that are no longer in use.
+You can't call a class method or an ordinary function on a class that
+has been collected that way.
+
+The hash randomisation is certain to reveal hidden assumptions about
+some particular ordering of hash elements, and outright bugs: it
+revealed a few bugs in the Perl core and core modules.
+
+To disable the hash randomisation in runtime, set the environment
+variable PERL_HASH_SEED to 0 (zero) before running Perl (for more
+information see L<perlrun/PERL_HASH_SEED>), or to disable the feature
+completely in compile time, compile with C<-DNO_HASH_SEED> (see F<INSTALL>).
+
+See L<perlsec/"Algorithmic Complexity Attacks"> for the original
+rationale behind this change.
+
+=head2 UTF-8 On Filehandles No Longer Activated By Locale
+
+In Perl 5.8.0 all filehandles, including the standard filehandles,
+were implicitly set to be in Unicode UTF-8 if the locale settings
+indicated the use of UTF-8. This feature caused too many problems,
+so the feature was turned off and redesigned: see L</"Core Enhancements">.
+
+=head2 Single-number v-strings are no longer v-strings before "=>"
+
+The version strings or v-strings (see L<perldata/"Version Strings">)
+feature introduced in Perl 5.6.0 has been a source of some confusion--
+especially when the user did not want to use it, but Perl thought it
+knew better. Especially troublesome has been the feature that before
+a "=>" a version string (a "v" followed by digits) has been interpreted
+as a v-string instead of a string literal. In other words:
+
+ %h = ( v65 => 42 );
+
+has meant since Perl 5.6.0
+
+ %h = ( 'A' => 42 );
+
+(at least in platforms of ASCII progeny) Perl 5.8.1 restored the
+more natural interpretation
+
+ %h = ( 'v65' => 42 );
+
+The multi-number v-strings like v65.66 and 65.66.67 still continue to
+be v-strings in Perl 5.8.
+
+=head2 (Win32) The -C Switch Has Been Repurposed
+
+The -C switch has changed in an incompatible way. The old semantics
+of this switch only made sense in Win32 and only in the "use utf8"
+universe in 5.6.x releases, and do not make sense for the Unicode
+implementation in 5.8.0. Since this switch could not have been used
+by anyone, it has been repurposed. The behavior that this switch
+enabled in 5.6.x releases may be supported in a transparent,
+data-dependent fashion in a future release.
+
+For the new life of this switch, see L<"UTF-8 no longer default under
+UTF-8 locales">, and L<perlrun/-C>.
+
+=head2 (Win32) The /d Switch Of cmd.exe
+
+Since version 5.8.1, perl uses the /d switch when running the cmd.exe shell
+internally for system(), backticks, and when opening pipes to external
+programs. The extra switch disables the execution of AutoRun commands
+from the registry, which is generally considered undesirable when
+running external programs. If you wish to retain compatibility with
+the older behavior, set PERL5SHELL in your environment to C<cmd /x/c>.
+
=head2 The C<$*> variable has been removed
C<$*>, which was deprecated in favor of the C</s> and C</m> regexp
=head1 Core Enhancements
+=head2 Assertions
+
+Perl 5.9.0 has experimental support for assertions. Note that hhe user
+interface is not fully stabilized yet, and it may change until the 5.10.0
+release. A new command-line switch, B<-A>, is used to activate
+assertions, which are declared with the C<assertions> pragma. See
+L<assertions>.
+
+=head2 Defined-or operators
+
+A new operator C<//> (defined-or) has been implemented.
+The following statement:
+
+ $a // $b
+
+is merely equivalent to
+
+ defined $a ? $a : $b
+
+and
+
+ $c //= $d;
+
+can be used instead of
+
+ $c = $d unless defined $c;
+
+This operator has the same precedence and associativity as C<||>.
+It has a low-precedence counterpart, C<err>, which has the same precedence
+and associativity as C<or>. Special care has been taken to ensure that
+those operators Do What You Mean while not breaking old code, but some
+edge cases involving the empty regular expression may now parse
+differently. See L<perlop> for details.
+
+=head2 UTF-8 no longer default under UTF-8 locales
+
+In Perl 5.8.0 many Unicode features were introduced. One of them
+was found to be of more nuisance than benefit: the automagic
+(and silent) "UTF-8-ification" of filehandles, including the
+standard filehandles, if the user's locale settings indicated
+use of UTF-8.
+
+For example, if you had C<en_US.UTF-8> as your locale, your STDIN and
+STDOUT were automatically "UTF-8", in other words an implicit
+binmode(..., ":utf8") was made. This meant that trying to print, say,
+chr(0xff), ended up printing the bytes 0xc3 0xbf. Hardly what
+you had in mind unless you were aware of this feature of Perl 5.8.0.
+The problem is that the vast majority of people weren't: for example
+in RedHat releases 8 and 9 the B<default> locale setting is UTF-8, so
+all RedHat users got UTF-8 filehandles, whether they wanted it or not.
+The pain was intensified by the Unicode implementation of Perl 5.8.0
+(still) having nasty bugs, especially related to the use of s/// and
+tr///. (Bugs that have been fixed in 5.8.1)
+
+Therefore a decision was made to backtrack the feature and change it
+from implicit silent default to explicit conscious option. The new
+Perl command line option C<-C> and its counterpart environment
+variable PERL_UNICODE can now be used to control how Perl and Unicode
+interact at interfaces like I/O and for example the command line
+arguments. See L<perlrun/-C> and L<perlrun/PERL_UNICODE> for more
+information.
+
+=head2 Unsafe signals again available
+
+In Perl 5.8.0 the so-called "safe signals" were introduced. This
+means that Perl no longer handles signals immediately but instead
+"between opcodes", when it is safe to do so. The earlier immediate
+handling easily could corrupt the internal state of Perl, resulting
+in mysterious crashes.
+
+However, the new safer model has its problems too. Because now an
+opcode, a basic unit of Perl execution, is never interrupted but
+instead let to run to completion, certain operations that can take a
+long time now really do take a long time. For example, certain
+network operations have their own blocking and timeout mechanisms, and
+being able to interrupt them immediately would be nice.
+
+Therefore perl 5.8.1 introduced a "backdoor" to restore the pre-5.8.0
+(pre-5.7.3, really) signal behaviour. Just set the environment variable
+PERL_SIGNALS to C<unsafe>, and the old immediate (and unsafe)
+signal handling behaviour returns. See L<perlrun/PERL_SIGNALS>
+and L<perlipc/"Deferred Signals (Safe Signals)">.
+
+In completely unrelated news, you can now use safe signals with
+POSIX::SigAction. See L<POSIX/POSIX::SigAction>.
+
=head2 Tied Arrays with Negative Array Indices
Formerly, the indices passed to C<FETCH>, C<STORE>, C<EXISTS>, and
C<DELETE> methods in tied array class were always non-negative. If
the actual argument was negative, Perl would call FETCHSIZE implicitly
and add the result to the index before passing the result to the tied
-array method. This behavior is now optional. If the tied array class
+array method. This behaviour is now optional. If the tied array class
contains a package variable named C<$NEGATIVE_INDICES> which is set to
a true value, negative values will be passed to C<FETCH>, C<STORE>,
C<EXISTS>, and C<DELETE> unchanged.
+=head2 local ${$x}
+
+The syntaxes
+
+ local ${$x}
+ local @{$x}
+ local %{$x}
+
+now do localise variables, given that the $x is a valid variable name.
+
+=head2 Unicode Character Database 4.0.0
+
+The copy of the Unicode Character Database included in Perl 5.8 has
+been updated to 4.0.0 from 3.2.0. This means for example that the
+Unicode character properties are as in Unicode 4.0.0.
+
+=head2 Miscellaneous Enhancements
+
+C<unpack()> now defaults to unpacking the C<$_>.
+
+C<map> in void context is no longer expensive. C<map> is now context
+aware, and will not construct a list if called in void context.
+
+If a socket gets closed by the server while printing to it, the client
+now gets a SIGPIPE. While this new feature was not planned, it fell
+naturally out of PerlIO changes, and is to be considered an accidental
+feature.
+
+PerlIO::get_layers(FH) returns the names of the PerlIO layers
+active on a filehandle.
+
+PerlIO::via layers can now have an optional UTF8 method to
+indicate whether the layer wants to "auto-:utf8" the stream.
+
+utf8::is_utf8() has been added as a quick way to test whether
+a scalar is encoded internally in UTF-8 (Unicode).
+
=head1 Modules and Pragmata
+=head2 Updated Modules And Pragmata
+
+The following modules and pragmata have been updated since Perl 5.8.0:
+
+=over 4
+
+=item base
+
+=item B::Bytecode
+
+In much better shape than it used to be. Still far from perfect, but
+maybe worth a try.
+
+=item B::Concise
+
+=item B::Deparse
+
+=item Benchmark
+
+An optional feature, C<:hireswallclock>, now allows for high
+resolution wall clock times (uses Time::HiRes).
+
+=item ByteLoader
+
+See B::Bytecode.
+
+=item bytes
+
+Now has bytes::substr.
+
+=item CGI
+
+=item charnames
+
+One can now have custom character name aliases.
+
+=item CPAN
+
+There is now a simple command line frontend to the CPAN.pm
+module called F<cpan>.
+
+=item Data::Dumper
+
+A new option, Pair, allows choosing the separator between hash keys
+and values.
+
+=item DB_File
+
+=item Devel::PPPort
+
+=item Digest::MD5
+
+=item Encode
+
+Significant updates on the encoding pragma functionality
+(tr/// and the DATA filehandle, formats).
+
+If a filehandle has been marked as to have an encoding, unmappable
+characters are detected already during input, not later (when the
+corrupted data is being used).
+
+The ISO 8859-6 conversion table has been corrected (the 0x30..0x39
+erroneously mapped to U+0660..U+0669, instead of U+0030..U+0039). The
+GSM 03.38 conversion did not handle escape sequences correctly. The
+UTF-7 encoding has been added (making Encode feature-complete with
+Unicode::String).
+
+=item fields
+
+=item libnet
+
+=item Math::BigInt
+
+A lot of bugs have been fixed since v1.60, the version included in Perl
+v5.8.0. Especially noteworthy are the bug in Calc that caused div and mod to
+fail for some large values, and the fixes to the handling of bad inputs.
+
+Some new features were added, e.g. the broot() method, you can now pass
+parameters to config() to change some settings at runtime, and it is now
+possible to trap the creation of NaN and infinity.
+
+As usual, some optimizations took place and made the math overall a tad
+faster. In some cases, quite a lot faster, actually. Especially alternative
+libraries like Math::BigInt::GMP benefit from this. In addition, a lot of the
+quite clunky routines like fsqrt() and flog() are now much much faster.
+
+=item MIME::Base64
+
+=item NEXT
+
+Diamond inheritance now works.
+
+=item Net::Ping
+
+=item PerlIO::scalar
+
+Reading from non-string scalars (like the special variables, see
+L<perlvar>) now works.
+
+=item podlators
+
+=item Pod::LaTeX
+
+=item PodParsers
+
+=item Pod::Perldoc
+
+Complete rewrite. As a side-effect, no longer refuses to startup when
+run by root.
+
+=item Scalar::Util
+
+New utilities: refaddr, isvstring, looks_like_number, set_prototype.
+
+=item Storable
+
+Can now store code references (via B::Deparse, so not foolproof).
+
+=item strict
+
+Earlier versions of the strict pragma did not check the parameters
+implicitly passed to its "import" (use) and "unimport" (no) routine.
+This caused the false idiom such as:
+
+ use strict qw(@ISA);
+ @ISA = qw(Foo);
+
+This however (probably) raised the false expectation that the strict
+refs, vars and subs were being enforced (and that @ISA was somehow
+"declared"). But the strict refs, vars, and subs are B<not> enforced
+when using this false idiom.
+
+Starting from Perl 5.8.1, the above B<will> cause an error to be
+raised. This may cause programs which used to execute seemingly
+correctly without warnings and errors to fail when run under 5.8.1.
+This happens because
+
+ use strict qw(@ISA);
+
+will now fail with the error:
+
+ Unknown 'strict' tag(s) '@ISA'
+
+The remedy to this problem is to replace this code with the correct idiom:
+
+ use strict;
+ use vars qw(@ISA);
+ @ISA = qw(Foo);
+
+=item Term::ANSIcolor
+
+=item Test::Harness
+
+Now much more picky about extra or missing output from test scripts.
+
+=item Test::More
+
+=item Test::Simple
+
+=item Text::Balanced
+
+=item Time::HiRes
+
+Use of nanosleep(), if available, allows mixing subsecond sleeps with
+alarms.
+
+=item threads
+
+Several fixes, for example for join() problems and memory
+leaks. In some platforms (like Linux) that use glibc the minimum memory
+footprint of one ithread has been reduced by several hundred kilobytes.
+
+=item threads::shared
+
+Many memory leaks have been fixed.
+
+=item Unicode::Collate
+
+=item Unicode::Normalize
+
+=item Win32::GetFolderPath
+
+=item Win32::GetOSVersion
+
+Now returns extra information.
+
+=back
+
=head1 Utility Changes
+The C<h2xs> utility now produces a more modern layout:
+F<Foo-Bar/lib/Foo/Bar.pm> instead of F<Foo/Bar/Bar.pm>.
+Also, the boilerplate test is now called F<t/Foo-Bar.t>
+instead of F<t/1.t>.
+
+The Perl debugger (F<lib/perl5db.pl>) has now been extensively
+documented and bugs found while documenting have been fixed.
+
+C<perldoc> has been rewritten from scratch to be more robust and
+featureful.
+
+C<perlcc -B> works now at least somewhat better, while C<perlcc -c>
+is rather more broken. (The Perl compiler suite as a whole continues
+to be experimental.)
+
=head1 New Documentation
+perl573delta has been added to list the differences between the
+(now quite obsolete) development releases 5.7.2 and 5.7.3.
+
+perl58delta and perl581delta have been added: these are the perldeltas
+of 5.8.0 and 5.8.1, detailing the differences respectively between
+5.6.0 and 5.8.0, and between 5.8.0 and 5.8.1.
+
+perlartistic has been added: it is the Artistic License in pod format,
+making it easier for modules to refer to it.
+
+perlcheat has been added: it is a Perl cheat sheet.
+
+perlgpl has been added: it is the GNU General Public License in pod
+format, making it easier for modules to refer to it.
+
+perlmacosx has been added to tell about the installation and use
+of Perl in Mac OS X.
+
+perlos400 has been added to tell about the installation and use
+of Perl in OS/400 PASE.
+
+perlreref has been added: it is a regular expressions quick reference.
+
=head1 Performance Enhancements
=head1 Installation and Configuration Improvements
+The UNIX standard Perl location, F</usr/bin/perl>, is no longer
+overwritten by default if it exists. This change was very prudent
+because so many UNIX vendors already provide a F</usr/bin/perl>,
+but simultaneously many system utilities may depend on that
+exact version of Perl, so better not to overwrite it.
+
+One can now specify installation directories for site and vendor man
+and HTML pages, and site and vendor scripts. See F<INSTALL>.
+
+One can now specify a destination directory for Perl installation
+by specifying the DESTDIR variable for C<make install>. (This feature
+is slightly different from the previous C<Configure -Dinstallprefix=...>.)
+See F<INSTALL>.
+
+gcc versions 3.x introduced a new warning that caused a lot of noise
+during Perl compilation: C<gcc -Ialreadyknowndirectory (warning:
+changing search order)>. This warning has now been avoided by
+Configure weeding out such directories before the compilation.
+
+One can now build subsets of Perl core modules by using the
+Configure flags C<-Dnoextensions=...> and C<-Donlyextensions=...>,
+see F<INSTALL>.
+
+=head2 Platform-specific enhancements
+
+In Cygwin Perl can now be built with threads (C<Configure -Duseithreads>).
+This works with both Cygwin 1.3.22 and Cygwin 1.5.3.
+
+In newer FreeBSD releases Perl 5.8.0 compilation failed because of
+trying to use F<malloc.h>, which in FreeBSD is just a dummy file, and
+a fatal error to even try to use. Now F<malloc.h> is not used.
+
+Perl is now known to build also in Hitachi HI-UXMPP.
+
+Perl is now known to build again in LynxOS.
+
+Mac OS X now installs with Perl version number embedded in
+installation directory names for easier upgrading of user-compiled
+Perl, and the installation directories in general are more standard.
+In other words, the default installation no longer breaks the
+Apple-provided Perl. On the other hand, with C<Configure -Dprefix=/usr>
+you can now really replace the Apple-supplied Perl (B<please be careful>).
+
+Mac OS X now builds Perl statically by default. This change was done
+mainly for faster startup times. The Apple-provided Perl is still
+dynamically linked and shared, and you can enable the sharedness for
+your own Perl builds by C<Configure -Duseshrplib>.
+
+Perl has been ported to IBM's OS/400 PASE environment. The best way
+to build a Perl for PASE is to use an AIX host as a cross-compilation
+environment. See README.os400.
+
+Yet another cross-compilation option has been added: now Perl builds
+on OpenZaurus, an Linux distribution based on Mandrake + Embedix for
+the Sharp Zaurus PDA. See the Cross/README file.
+
+Tru64 when using gcc 3 drops the optimisation for F<toke.c> to C<-O2>
+because of gigantic memory use with the default C<-O3>.
+
+Tru64 can now build Perl with the newer Berkeley DBs.
+
+Building Perl on WinCE has been much enhanced, see F<README.ce>
+and F<README.perlce>.
+
=head1 Selected Bug Fixes
+=head2 Closures, eval and lexicals
+
+There have been many fixes in the area of anonymous subs, lexicals and
+closures. Although this means that Perl is now more "correct", it is
+possible that some existing code will break that happens to rely on
+the faulty behaviour. In practice this is unlikely unless your code
+contains a very complex nesting of anonymous subs, evals and lexicals.
+
+=head2 Generic fixes
+
+If an input filehandle is marked C<:utf8> and Perl sees illegal UTF-8
+coming in when doing C<< <FH> >>, if warnings are enabled a warning is
+immediately given - instead of being silent about it and Perl being
+unhappy about the broken data later. (The C<:encoding(utf8)> layer
+also works the same way.)
+
+binmode(SOCKET, ":utf8") only worked on the input side, not on the
+output side of the socket. Now it works both ways.
+
+For threaded Perls certain system database functions like getpwent()
+and getgrent() now grow their result buffer dynamically, instead of
+failing. This means that at sites with lots of users and groups the
+functions no longer fail by returning only partial results.
+
+Perl 5.8.0 had accidentally broken the capability for users
+to define their own uppercase<->lowercase Unicode mappings
+(as advertised by the Camel). This feature has been fixed and
+is also documented better.
+
+In 5.8.0 this
+
+ $some_unicode .= <FH>;
+
+didn't work correctly but instead corrupted the data. This has now
+been fixed.
+
+Tied methods like FETCH etc. may now safely access tied values, i.e.
+resulting in a recursive call to FETCH etc. Remember to break the
+recursion, though.
+
+At startup Perl blocks the SIGFPE signal away since there isn't much
+Perl can do about it. Previously this blocking was in effect also for
+programs executed from within Perl. Now Perl restores the original
+SIGFPE handling routine, whatever it was, before running external
+programs.
+
+Linenumbers in Perl scripts may now be greater than 65536, or 2**16.
+(Perl scripts have always been able to be larger than that, it's just
+that the linenumber for reported errors and warnings have "wrapped
+around".) While scripts that large usually indicate a need to rethink
+your code a bit, such Perl scripts do exist, for example as results
+from generated code. Now linenumbers can go all the way to
+4294967296, or 2**32.
+
+=head2 Platform-specific fixes
+
+Linux
+
+=over 4
+
+=item *
+
+Setting $0 works again (with certain limitations that
+Perl cannot do much about: see L<perlvar/$0>)
+
+=back
+
+HP-UX
+
+=over 4
+
+=item *
+
+Setting $0 now works.
+
+=back
+
+VMS
+
+=over 4
+
+=item *
+
+Configuration now tests for the presence of C<poll()>, and IO::Poll
+now uses the vendor-supplied function if detected.
+
+=item *
+
+A rare access violation at Perl start-up could occur if the Perl image was
+installed with privileges or if there was an identifier with the
+subsystem attribute set in the process's rightslist. Either of these
+circumstances triggered tainting code that contained a pointer bug.
+The faulty pointer arithmetic has been fixed.
+
+=item *
+
+The length limit on values (not keys) in the %ENV hash has been raised
+from 255 bytes to 32640 bytes (except when the PERL_ENV_TABLES setting
+overrides the default use of logical names for %ENV). If it is
+necessary to access these long values from outside Perl, be aware that
+they are implemented using search list logical names that store the
+value in pieces, each 255-byte piece (up to 128 of them) being an
+element in the search list. When doing a lookup in %ENV from within
+Perl, the elements are combined into a single value. The existing
+VMS-specific ability to access individual elements of a search list
+logical name via the $ENV{'foo;N'} syntax (where N is the search list
+index) is unimpaired.
+
+=item *
+
+The piping implementation now uses local rather than global DCL
+symbols for inter-process communication.
+
+=item *
+
+File::Find could become confused when navigating to a relative
+directory whose name collided with a logical name. This problem has
+been corrected by adding directory syntax to relative path names, thus
+preventing logical name translation.
+
+=back
+
+Win32
+
+=over 4
+
+=item *
+
+A memory leak in the fork() emulation has been fixed.
+
+=item *
+
+The return value of the ioctl() built-in function was accidentally
+broken in 5.8.0. This has been corrected.
+
+=item *
+
+The internal message loop executed by perl during blocking operations
+sometimes interfered with messages that were external to Perl.
+This often resulted in blocking operations terminating prematurely or
+returning incorrect results, when Perl was executing under environments
+that could generate Windows messages. This has been corrected.
+
+=item *
+
+Pipes and sockets are now automatically in binary mode.
+
+=item *
+
+The four-argument form of select() did not preserve $! (errno) properly
+when there were errors in the underlying call. This is now fixed.
+
+=item *
+
+The "CR CR LF" problem of has been fixed, binmode(FH, ":crlf")
+is now effectively a no-op.
+
+=back
+
=head1 New or Changed Diagnostics
+All the warnings related to pack() and unpack() were made more
+informative and consistent.
+
+=head2 Changed "A thread exited while %d threads were running"
+
+The old version
+
+ A thread exited while %d other threads were still running
+
+was misleading because the "other" included also the thread giving
+the warning.
+
+=head2 Removed "Attempt to clear a restricted hash"
+
+It is not illegal to clear a restricted hash, so the warning
+was removed.
+
+=head2 New "Illegal declaration of anonymous subroutine"
+
+You must specify the block of code for C<sub>.
+
+=head2 Changed "Invalid range "%s" in transliteration operator"
+
+The old version
+
+ Invalid [] range "%s" in transliteration operator
+
+was simply wrong because there are no "[] ranges" in tr///.
+
+=head2 New "Missing control char name in \c"
+
+Self-explanatory.
+
+=head2 New "Newline in left-justified string for %s"
+
+The padding spaces would appear after the newline, which is
+probably not what you had in mind.
+
+=head2 New "Possible precedence problem on bitwise %c operator"
+
+If you think this
+
+ $x & $y == 0
+
+tests whether the bitwise AND of $x and $y is zero,
+you will like this warning.
+
+=head2 New "read() on %s filehandle %s"
+
+You cannot read() (or sysread()) from a closed or unopened filehandle.
+
+=head2 New "Tied variable freed while still in use"
+
+Something pulled the plug on a live tied variable, Perl plays
+safe by bailing out.
+
+=head2 New "To%s: illegal mapping '%s'"
+
+An illegal user-defined Unicode casemapping was specified.
+
+=head2 New "Use of freed value in iteration"
+
+Something modified the values being iterated over. This is not good.
+
=head1 Changed Internals
+These news matter to you only if you either write XS code or like to
+know about or hack Perl internals (using Devel::Peek or any of the
+C<B::> modules counts), or like to run Perl with the C<-D> option.
+
+The embedding examples of L<perlembed> have been reviewed to be
+uptodate and consistent: for example, the correct use of
+PERL_SYS_INIT3() and PERL_SYS_TERM().
+
+Extensive reworking of the pad code (the code responsible
+for lexical variables) has been conducted by Dave Mitchell.
+
+Extensive work on the v-strings by John Peacock.
+
+UTF-8 length and position cache: to speed up the handling of Unicode
+(UTF-8) scalars, a cache was introduced. Potential problems exist if
+an extension bypasses the official APIs and directly modifies the PV
+of an SV: the UTF-8 cache does not get cleared as it should.
+
+APIs obsoleted in Perl 5.8.0, like sv_2pv, sv_catpvn, sv_catsv,
+sv_setsv, are again available.
+
+Certain Perl core C APIs like cxinc and regatom are no longer
+available at all to code outside the Perl core of the Perl core
+extensions. This is intentional. They never should have been
+available with the shorter names, and if you application depends on
+them, you should (be ashamed and) contact perl5-porters to discuss
+what are the proper APIs.
+
+Certain Perl core C APIs like C<Perl_list> are no longer available
+without their C<Perl_> prefix. If your XS module stops working
+because some functions cannot be found, in many cases a simple fix is
+to add the C<Perl_> prefix to the function and the thread context
+C<aTHX_> as the first argument of the function call. This is also how
+it should always have been done: letting the Perl_-less forms to leak
+from the core was an accident. For cleaner embedding you can also
+force this for all APIs by defining at compile time the cpp define
+PERL_NO_SHORT_NAMES.
+
+Perl_save_bool() has been added.
+
+Regexp objects (those created with C<qr>) now have S-magic rather than
+R-magic. This fixed regexps of the form /...(??{...;$x})/ to no
+longer ignore changes made to $x. The S-magic avoids dropping
+the caching optimization and making (??{...}) constructs obscenely
+slow (and consequently useless). See also L<perlguts/"Magic Variables">.
+Regexp::Copy was affected by this change.
+
+The Perl internal debugging macros DEBUG() and DEB() have been renamed
+to PERL_DEBUG() and PERL_DEB() to avoid namespace conflicts.
+
+C<-DL> removed (the leaktest had been broken and unsupported for years,
+use alternative debugging mallocs or tools like valgrind and Purify).
+
+Verbose modifier C<v> added for C<-DXv> and C<-Dsv>, see L<perlrun>.
+
=head1 New Tests
+In Perl 5.8.0 there were about 69000 separate tests in about 700 test files,
+in Perl 5.9.0 there are about 77000 separate tests in about 780 test files.
+The exact numbers depend on the Perl configuration and on the operating
+system platform.
+
=head1 Known Problems
+The hash randomisation mentioned in L</Incompatible Changes> is definitely
+problematic: it will wake dormant bugs and shake out bad assumptions.
+
+Many of the rarer platforms that worked 100% or pretty close to it
+with perl 5.8.0 have been left a little bit untended since their
+maintainers have been otherwise busy lately, and therefore there will
+be more failures on those platforms. Such platforms include Mac OS
+Classic, IBM z/OS (and other EBCDIC platforms), and NetWare. The most
+common Perl platforms (Unix and Unix-like, Microsoft platforms, and
+VMS) have large enough testing and expert population that they are
+doing well.
+
+=head2 Tied hashes in scalar context
+
+Tied hashes do not currently return anything useful in scalar context,
+for example when used as boolean tests:
+
+ if (%tied_hash) { ... }
+
+The current nonsensical behaviour is always to return false,
+regardless of whether the hash is empty or has elements.
+
+The root cause is that there is no interface for the implementors of
+tied hashes to implement the behaviour of a hash in scalar context.
+
+=head2 Net::Ping 450_service and 510_ping_udp failures
+
+The subtests 9 and 18 of lib/Net/Ping/t/450_service.t, and the
+subtest 2 of lib/Net/Ping/t/510_ping_udp.t might fail if you have
+an unusual networking setup. For example in the latter case the
+test is trying to send a UDP ping to the IP address 127.0.0.1.
+
+=head2 B::C
+
+The C-generating compiler backend B::C (the frontend being
+C<perlcc -c>) is even more broken than it used to be because of
+the extensive lexical variable changes. (The good news is that
+B::Bytecode and ByteLoader are better than they used to be.)
+
=head1 Platform Specific Problems
+=head2 EBCDIC Platforms
+
+IBM z/OS and other EBCDIC platforms continue to be problematic
+regarding Unicode support. Many Unicode tests are skipped when
+they really should be fixed.
+
+=head2 Cygwin 1.5 problems
+
+In Cygwin 1.5 the F<io/tell> and F<op/sysio> tests have failures for
+some yet unknown reason. In 1.5.5 the threads tests stress_cv,
+stress_re, and stress_string are failing unless the environment
+variable PERLIO is set to "perlio" (which makes also the io/tell
+failure go away).
+
+Perl 5.8.1 does build and work well with Cygwin 1.3: with (uname -a)
+C<CYGWIN_NT-5.0 ... 1.3.22(0.78/3/2) 2003-03-18 09:20 i686 ...>
+a 100% "make test" was achieved with C<Configure -des -Duseithreads>.
+
+=head2 HP-UX: HP cc warnings about sendfile and sendpath
+
+With certain HP C compiler releases (e.g. B.11.11.02) you will
+get many warnings like this (lines wrapped for easier reading):
+
+ cc: "/usr/include/sys/socket.h", line 504: warning 562:
+ Redeclaration of "sendfile" with a different storage class specifier:
+ "sendfile" will have internal linkage.
+ cc: "/usr/include/sys/socket.h", line 505: warning 562:
+ Redeclaration of "sendpath" with a different storage class specifier:
+ "sendpath" will have internal linkage.
+
+The warnings show up both during the build of Perl and during certain
+lib/ExtUtils tests that invoke the C compiler. The warning, however,
+is not serious and can be ignored.
+
+=head2 IRIX: t/uni/tr_7jis.t falsely failing
+
+The test t/uni/tr_7jis.t is known to report failure under 'make test'
+or the test harness with certain releases of IRIX (at least IRIX 6.5
+and MIPSpro Compilers Version 7.3.1.1m), but if run manually the test
+fully passes.
+
+=head2 Mac OS X: no usemymalloc
+
+The Perl malloc (C<-Dusemymalloc>) does not work at all in Mac OS X.
+This is not that serious, though, since the native malloc works just
+fine.
+
+=head2 Tru64: No threaded builds with GNU cc (gcc)
+
+In the latest Tru64 releases (e.g. v5.1B or later) gcc cannot be used
+to compile a threaded Perl (-Duseithreads) because the system
+C<< <pthread.h> >> file doesn't know about gcc.
+
+=head2 Win32: sysopen, sysread, syswrite
+
+As of the 5.8.0 release, sysopen()/sysread()/syswrite() do not behave
+like they used to in 5.6.1 and earlier with respect to "text" mode.
+These built-ins now always operate in "binary" mode (even if sysopen()
+was passed the O_TEXT flag, or if binmode() was used on the file
+handle). Note that this issue should only make a difference for disk
+files, as sockets and pipes have always been in "binary" mode in the
+Windows port. As this behavior is currently considered a bug,
+compatible behavior may be re-introduced in a future release. Until
+then, the use of sysopen(), sysread() and syswrite() is not supported
+for "text" mode operations.
+
+=head1 TODO
+
+Here are some things that are planned for perl 5.10.0 :
+
+=over 4
+
+=item *
+
+Various Copy-On-Write techniques will be investigated in hopes
+of speeding up Perl.
+
+=item *
+
+CPANPLUS, Inline, and Module::Build will become core modules.
+
+=item *
+
+The ability to write true lexically scoped pragmas will be introduced,
+perhaps via a C<pragma> pragma.
+
+=item *
+
+Work will continue on the bytecompiler and byteloader.
+
+=item *
+
+v-strings as they currently exist are scheduled to be deprecated. The
+v-less form (1.2.3) will become a "version object" when used with C<use>,
+C<require>, and C<$VERSION>. $^V will also be a "version object" so the
+printf("%vd",...) construct will no longer be needed. The v-ful version
+(v1.2.3) will become obsolete. The equivalence of strings and v-strings (e.g.
+that currently 5.8.0 is equal to "\5\8\0") will go away. B<There may be no
+deprecation warning for v-strings>, though: it is quite hard to detect when
+v-strings are being used safely, and when they are not.
+
+=back
+
=head1 Reporting Bugs
If you find what you think is a bug, you might check the articles
program included with your release. Be sure to trim your bug down
to a tiny but sufficient test case. Your bug report, along with the
output of C<perl -V>, will be sent off to perlbug@perl.org to be
-analysed by the Perl porting team.
+analysed by the Perl porting team. You can browse and search
+the Perl 5 bugs at F<http://bugs.perl.org/>.
=head1 SEE ALSO
projects / p5sagit/p5-mst-13.2.git / blobdiff