New tlperl part XI

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+=head1 NAME
+
+perl570delta - what's new for perl v5.7.0
+
+=head1 DESCRIPTION
+
+This document describes differences between the 5.6.0 release and
+the 5.7.0 release.
+
+=head1 Security Vulnerability Closed
+
+A potential security vulnerability in the optional suidperl component
+of Perl has been identified.  suidperl is neither built nor installed
+by default.  As of September the 2nd, 2000, the only known vulnerable
+platform is Linux, most likely all Linux distributions.  CERT and
+various vendors have been alerted about the vulnerability.
+
+The problem was caused by Perl trying to report a suspected security
+exploit attempt using an external program, /bin/mail.  On Linux
+platforms the /bin/mail program had an undocumented feature which
+when combined with suidperl gave access to a root shell, resulting in
+a serious compromise instead of reporting the exploit attempt.  If you
+don't have /bin/mail, or if you have 'safe setuid scripts', or if
+suidperl is not installed, you are safe.
+
+The exploit attempt reporting feature has been completely removed from
+the Perl 5.7.0 release, so that particular vulnerability isn't there
+anymore.  However, further security vulnerabilities are,
+unfortunately, always possible.  The suidperl code is being reviewed
+and if deemed too risky to continue to be supported, it may be
+completely removed from future releases.  In any case, suidperl should
+only be used by security experts who know exactly what they are doing
+and why they are using suidperl instead of some other solution such as
+sudo ( see http://www.courtesan.com/sudo/ ).
+
+=head1 Incompatible Changes
+
+=over 4
+
+=item *
+
+Arrays now always interpolate into double-quoted strings:
+constructs like "foo@bar" now always assume C<@bar> is an array,
+whether or not the compiler has seen use of C<@bar>.
+
+=item *
+
+The semantics of bless(REF, REF) were unclear and until someone proves
+it to make some sense, it is forbidden.
+
+=item *
+
+A reference to a reference now stringify as "REF(0x81485ec)" instead
+of "SCALAR(0x81485ec)" in order to be more consistent with the return
+value of ref().
+
+=item *
+
+The very dusty examples in the eg/ directory have been removed.
+Suggestions for new shiny examples welcome but the main issue is that
+the examples need to be documented, tested and (most importantly)
+maintained.
+
+=item *
+
+The obsolete chat2 library that should never have been allowed
+to escape the laboratory has been decommissioned.
+
+=item *
+
+The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
+recognised but now cause fatal errors.  The previous behaviour of
+ignoring them by default and warning if requested was unacceptable
+since it, in a way, falsely promised that the features could be used.
+
+=item *
+
+The (bogus) escape sequences \8 and \9 now give an optional warning
+("Unrecognized escape passed through").  There is no need to \-escape
+any C<\w> character.
+
+=item *
+
+lstat(FILEHANDLE) now gives a warning because the operation makes no sense.
+In future releases this may become a fatal error.
+
+=item *
+
+The long deprecated uppercase aliases for the string comparison
+operators (EQ, NE, LT, LE, GE, GT) have now been removed.
+
+=item *
+
+The regular expression captured submatches ($1, $2, ...) are now
+more consistently unset if the match fails, instead of leaving false
+data lying around in them.
+
+=item *
+
+The tr///C and tr///U features have been removed and will not return;
+the interface was a mistake.  Sorry about that.  For similar
+functionality, see pack('U0', ...) and pack('C0', ...).
+
+=back
+
+=head1 Core Enhancements
+
+=over 4
+
+=item *
+
+C<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
+in multiple arguments.)
+
+=item *
+
+my __PACKAGE__ $obj now works.
+
+=item *
+
+C<no Module;> now works even if there is no "sub unimport" in the Module.
+
+=item *
+
+The numerical comparison operators return C<undef> if either operand
+is a NaN.  Previously the behaviour was unspecified.
+
+=item *
+
+C<pack('U0a*', ...)> can now be used to force a string to UTF-8.
+
+=item *
+
+prototype(\&) is now available.
+
+=item *
+
+There is now an UNTIE method.
+
+=back
+
+=head1 Modules and Pragmata
+
+=head2 New Modules
+
+=over 4
+
+=item *
+
+File::Temp allows one to create temporary files and directories in an
+easy, portable, and secure way.
+
+=item *
+
+Storable gives persistence to Perl data structures by allowing the
+storage and retrieval of Perl data to and from files in a fast and
+compact binary format.
+
+=back
+
+=head2 Updated And Improved Modules and Pragmata
+
+=over 4
+
+=item *
+
+The following independently supported modules have been updated to
+newer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
+the podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
+
+=item *
+
+Bug fixes and minor enhancements have been applied to B::Deparse,
+Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
+Math::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
+Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
+pragma.
+
+=item *
+
+The attributes::reftype() now works on tied arguments.
+
+=item *
+
+AutoLoader can now be disabled with C<no AutoLoader;>,
+
+=item *
+
+The English module can now be used without the infamous performance
+hit by saying
+
+	use English '-no_performance_hit';
+
+(Assuming, of course, that one doesn't need the troublesome variables
+C<$`>, C<$&>, or C<$'>.)  Also, introduced C<@LAST_MATCH_START> and
+C<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
+
+=item *
+
+File::Find now has pre- and post-processing callbacks.  It also
+correctly changes directories when chasing symbolic links.  Callbacks
+(naughtily) exiting with "next;" instead of "return;" now work.
+
+=item *
+
+File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
+prototype mismatch with CORE::glob().
+
+=item *
+
+IPC::Open3 now allows the use of numeric file descriptors.
+
+=item *
+
+use lib now works identically to @INC.  Removing directories
+with 'no lib' now works.
+
+=item *
+
+C<%INC> now localised in a Safe compartment so that use/require work.
+
+=item *
+
+The Shell module now has an OO interface.
+
+=back
+
+=head1 Utility Changes
+
+=over 4
+
+=item *
+
+The Emacs perl mode (emacs/cperl-mode.el) has been updated to version
+4.31.
+
+=item *
+
+Perlbug is now much more robust.  It also sends the bug report to
+perl.org, not perl.com.
+
+=item *
+
+The perlcc utility has been rewritten and its user interface (that is,
+command line) is much more like that of the Unix C compiler, cc.
+
+=item *
+
+The xsubpp utility for extension writers now understands POD
+documentation embedded in the *.xs files.
+
+=back
+
+=head1 New Documentation
+
+=over 4
+
+=item *
+
+perl56delta details the changes between the 5.005 release and the
+5.6.0 release.
+
+=item *
+
+perldebtut is a Perl debugging tutorial.
+
+=item *
+
+perlebcdic contains considerations for running Perl on EBCDIC platforms.
+Note that unfortunately EBCDIC platforms that used to supported back in
+Perl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
+bring them back to the fold.  
+
+=item *
+
+perlnewmod tells about writing and submitting a new module.
+
+=item *
+
+perlposix-bc explains using Perl on the POSIX-BC platform
+(an EBCDIC mainframe platform).
+
+=item *
+
+perlretut is a regular expression tutorial.
+
+=item *
+
+perlrequick is a regular expressions quick-start guide.
+Yes, much quicker than perlretut.
+
+=item *
+
+perlutil explains the command line utilities packaged with the Perl
+distribution.
+
+=back
+
+=head1 Performance Enhancements
+
+=over 4
+
+=item *
+
+map() that changes the size of the list should now work faster.
+
+=item *
+
+sort() has been changed to use mergesort internally as opposed to the
+earlier quicksort.  For very small lists this may result in slightly
+slower sorting times, but in general the speedup should be at least
+20%.  Additional bonuses are that the worst case behaviour of sort()
+is now better (in computer science terms it now runs in time O(N log N),
+as opposed to quicksort's Theta(N**2) worst-case run time behaviour),
+and that sort() is now stable (meaning that elements with identical
+keys will stay ordered as they were before the sort).
+
+=back
+
+=head1 Installation and Configuration Improvements
+
+=head2 Generic Improvements
+
+=over 4
+
+=item *
+
+INSTALL now explains how you can configure Perl to use 64-bit
+integers even on non-64-bit platforms.
+
+=item *
+
+Policy.sh policy change: if you are reusing a Policy.sh file
+(see INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
+Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
+them will now be changed to the new prefix, /foo/bar.  (Previously
+only $prefix changed.)  If you do not like this new behaviour,
+specify prefix, siteprefix, and vendorprefix explicitly.
+
+=item *
+
+A new optional location for Perl libraries, otherlibdirs, is available.
+It can be used for example for vendor add-ons without disturbing Perl's
+own library directories.
+
+=item *
+
+In many platforms the vendor-supplied 'cc' is too stripped-down to
+build Perl (basically, 'cc' doesn't do ANSI C).  If this seems
+to be the case and 'cc' does not seem to be the GNU C compiler
+'gcc', an automatic attempt is made to find and use 'gcc' instead.
+
+=item *
+
+gcc needs to closely track the operating system release to avoid
+build problems. If Configure finds that gcc was built for a different
+operating system release than is running, it now gives a clearly visible
+warning that there may be trouble ahead.
+
+=item *
+
+If binary compatibility with the 5.005 release is not wanted, Configure
+no longer suggests including the 5.005 modules in @INC.
+
+=item *
+
+Configure C<-S> can now run non-interactively.
+
+=item *
+
+configure.gnu now works with options with whitespace in them.
+
+=item *
+
+installperl now outputs everything to STDERR.
+
+=item *
+
+$Config{byteorder} is now computed dynamically (this is more robust
+with "fat binaries" where an executable image contains binaries for
+more than one binary platform.)
+
+=back
+
+=head1 Selected Bug Fixes
+
+=over 4
+
+=item *
+
+Several debugger fixes: exit code now reflects the script exit code,
+condition C<"0"> now treated correctly, the C<d> command now checks
+line number, the C<$.> no longer gets corrupted, all debugger output now
+goes correctly to the socket if RemotePort is set.
+
+=item *
+
+C<*foo{FORMAT}> now works.
+
+=item *
+
+Lexical warnings now propagating correctly between scopes.
+
+=item *
+
+Line renumbering with eval and C<#line> now works.
+
+=item *
+
+Fixed numerous memory leaks, especially in eval "".
+
+=item *
+
+Modulus of unsigned numbers now works (4063328477 % 65535 used to
+return 27406, instead of 27047).
+
+=item *
+
+Some "not a number" warnings introduced in 5.6.0 eliminated to be
+more compatible with 5.005.  Infinity is now recognised as a number.
+
+=item *
+
+our() variables will not cause "will not stay shared" warnings.
+
+=item *
+
+pack "Z" now correctly terminates the string with "\0".
+
+=item *
+
+Fix password routines which in some shadow password platforms
+(e.g. HP-UX) caused getpwent() to return every other entry.
+
+=item *
+
+printf() no longer resets the numeric locale to "C".
+
+=item *
+
+C<q(a\\b)> now parses correctly as C<'a\\b'>.
+
+=item *
+
+Printing quads (64-bit integers) with printf/sprintf now works
+without the q L ll prefixes (assuming you are on a quad-capable platform).
+
+=item *
+
+Regular expressions on references and overloaded scalars now work.
+
+=item *
+
+scalar() now forces scalar context even when used in void context.
+
+=item *
+
+sort() arguments are now compiled in the right wantarray context
+(they were accidentally using the context of the sort() itself).
+
+=item *
+
+Changed the POSIX character class C<[[:space:]]> to include the (very
+rare) vertical tab character.  Added a new POSIX-ish character class
+C<[[:blank:]]> which stands for horizontal whitespace (currently,
+the space and the tab).
+
+=item *
+
+$AUTOLOAD, sort(), lock(), and spawning subprocesses
+in multiple threads simultaneously are now thread-safe.
+
+=item *
+
+Allow read-only string on left hand side of non-modifying tr///.
+
+=item *
+
+Several Unicode fixes (but still not perfect).
+
+=over 8
+
+=item *
+
+BOMs (byte order marks) in the beginning of Perl files
+(scripts, modules) should now be transparently skipped.
+UTF-16 (UCS-2) encoded Perl files should now be read correctly.
+
+=item *
+
+The character tables have been updated to Unicode 3.0.1.
+
+=item *
+
+chr() for values greater than 127 now create utf8 when under use
+utf8.
+
+=item *
+
+Comparing with utf8 data does not magically upgrade non-utf8 data into
+utf8.
+
+=item *
+
+C<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
+
+=item *
+
+Concatenation with the C<.> operator or via variable interpolation,
+C<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
+substitution with C<s///>, single-quoted UTF-8, should now work--in
+theory.
+
+=item *
+
+The C<tr///> operator now works I<slightly> better but is still rather
+broken.  Note that the C<tr///CU> functionality has been removed (but
+see pack('U0', ...)).
+
+=item *
+
+vec() now refuses to deal with characters >255.
+
+=item *
+
+Zero entries were missing from the Unicode classes like C<IsDigit>.
+
+=back
+
+=item *
+
+UNIVERSAL::isa no longer caches methods incorrectly.  (This broke
+the Tk extension with 5.6.0.)
+
+=back
+
+=head2 Platform Specific Changes and Fixes
+
+=over 4
+
+=item *
+
+BSDI 4.*
+
+Perl now works on post-4.0 BSD/OSes.
+
+=item *
+
+All BSDs
+
+Setting C<$0> now works (as much as possible; see perlvar for details).
+
+=item *
+
+Cygwin
+
+Numerous updates; currently synchronised with Cygwin 1.1.4.
+
+=item *
+
+EPOC
+
+EPOC update after Perl 5.6.0.  See README.epoc.
+
+=item *
+
+FreeBSD 3.*
+
+Perl now works on post-3.0 FreeBSDs.
+
+=item *
+
+HP-UX
+
+README.hpux updated; C<Configure -Duse64bitall> now almost works.
+
+=item *
+
+IRIX
+
+Numerous compilation flag and hint enhancements; accidental mixing
+of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
+
+=item *
+
+Linux
+
+Long doubles should now work (see INSTALL).
+
+=item *
+
+Mac OS Classic
+
+Compilation of the standard Perl distribution in Mac OS Classic should
+now work if you have the Metrowerks development environment and the
+missing Mac-specific toolkit bits.  Contact the macperl mailing list
+for details.
+
+=item *
+
+MPE/iX
+
+MPE/iX update after Perl 5.6.0.  See README.mpeix.
+
+=item *
+
+NetBSD/sparc
+
+Perl now works on NetBSD/sparc.
+
+=item *
+
+OS/2
+
+Now works with usethreads (see INSTALL).
+
+=item *
+
+Solaris
+
+64-bitness using the Sun Workshop compiler now works.
+
+=item *
+
+Tru64 (aka Digital UNIX, aka DEC OSF/1)
+
+The operating system version letter now recorded in $Config{osvers}.
+Allow compiling with gcc (previously explicitly forbidden).  Compiling
+with gcc still not recommended because buggy code results, even with
+gcc 2.95.2.
+
+=item *
+
+Unicos
+
+Fixed various alignment problems that lead into core dumps either
+during build or later; no longer dies on math errors at runtime;
+now using full quad integers (64 bits), previously was using 
+only 46 bit integers for speed.
+
+=item *
+
+VMS
+
+chdir() now works better despite a CRT bug; now works with MULTIPLICITY
+(see INSTALL); now works with Perl's malloc.
+
+=item *
+
+Windows
+
+=over 8
+
+=item *
+
+accept() no longer leaks memory.
+
+=item *
+
+Better chdir() return value for a non-existent directory.
+
+=item *
+
+New %ENV entries now propagate to subprocesses.
+
+=item *
+
+$ENV{LIB} now used to search for libs under Visual C.
+
+=item *
+
+A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
+
+=item *
+
+Allow REG_EXPAND_SZ keys in the registry.
+
+=item *
+
+Can now send() from all threads, not just the first one.
+
+=item *
+
+Fake signal handling reenabled, bugs and all.
+
+=item *
+
+Less stack reserved per thread so that more threads can run
+concurrently. (Still 16M per thread.)
+
+=item *
+
+C<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
+(works better when perl is running as service).
+
+=item *
+
+Better UNC path handling under ithreads.
+
+=item *
+
+wait() and waitpid() now work much better.
+
+=item *
+
+winsock handle leak fixed.
+
+=back
+
+=back
+
+=head1 New or Changed Diagnostics
+
+All regular expression compilation error messages are now hopefully
+easier to understand both because the error message now comes before
+the failed regex and because the point of failure is now clearly
+marked.
+
+The various "opened only for", "on closed", "never opened" warnings
+drop the C<main::> prefix for filehandles in the C<main> package,
+for example C<STDIN> instead of <main::STDIN>. 
+
+The "Unrecognized escape" warning has been extended to include C<\8>,
+C<\9>, and C<\_>.  There is no need to escape any of the C<\w> characters.
+
+=head1 Changed Internals
+
+=over 4
+
+=item *
+
+perlapi.pod (a companion to perlguts) now attempts to document the
+internal API.
+
+=item *
+
+You can now build a really minimal perl called microperl.
+Building microperl does not require even running Configure;
+C<make -f Makefile.micro> should be enough.  Beware: microperl makes
+many assumptions, some of which may be too bold; the resulting
+executable may crash or otherwise misbehave in wondrous ways.
+For careful hackers only.
+
+=item *
+
+Added rsignal(), whichsig(), do_join() to the publicised API.
+
+=item *
+
+Made possible to propagate customised exceptions via croak()ing.
+
+=item *
+
+Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
+
+=item *
+
+Now xsubs can have attributes just like subs.
+
+=back
+
+=head1 Known Problems
+
+=head2 Unicode Support Still Far From Perfect
+
+We're working on it.  Stay tuned.
+
+=head2 EBCDIC Still A Lost Platform
+
+The plan is to bring them back.
+
+=head2 Building Extensions Can Fail Because Of Largefiles
+
+Certain extensions like mod_perl and BSD::Resource are known to have
+issues with `largefiles', a change brought by Perl 5.6.0 in which file
+offsets default to 64 bits wide, where supported.  Modules may fail to
+compile at all or compile and work incorrectly.  Currently there is no
+good solution for the problem, but Configure now provides appropriate
+non-largefile ccflags, ldflags, libswanted, and libs in the %Config
+hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
+having problems can try configuring themselves without the
+largefileness.  This is admittedly not a clean solution, and the
+solution may not even work at all.  One potential failure is whether
+one can (or, if one can, whether it's a good idea) link together at
+all binaries with different ideas about file offsets, all this is
+platform-dependent.
+
+=head2 ftmp-security tests warn 'system possibly insecure'
+
+Don't panic.  Read INSTALL 'make test' section instead. 
+
+=head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
+
+If perl is configured with -Duse64bitall, the successful result of the
+subtest 10 of lib/posix may arrive before the successful result of the
+subtest 9, which confuses the test harness so much that it thinks the
+subtest 9 failed.
+
+=head2 Long Doubles Still Don't Work In Solaris
+
+The experimental long double support is still very much so in Solaris.
+(Other platforms like Linux and Tru64 are beginning to solidify in
+this area.)
+
+=head2 Linux With Sfio Fails op/misc Test 48
+
+No known fix.
+
+=head2 Storable tests fail in some platforms
+
+If any Storable tests fail the use of Storable is not advisable.
+
+=over 4
+
+=item *
+
+Many Storable tests fail on AIX configured with 64 bit integers.
+
+So far unidentified problems break Storable in AIX if Perl is
+configured to use 64 bit integers.  AIX in 32-bit mode works and
+other 64-bit platforms work with Storable.
+
+=item *
+
+DOS DJGPP may hang when testing Storable.
+
+=item *
+
+st-06compat fails in UNICOS and UNICOS/mk.
+
+This means that you cannot read old (pre-Storable-0.7) Storable images
+made in other platforms.
+
+=item *
+
+st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
+
+=back
+
+=head2 Threads Are Still Experimental
+
+Multithreading is still an experimental feature.  Some platforms
+emit the following message for lib/thr5005
+
+    #
+    # This is a KNOWN FAILURE, and one of the reasons why threading
+    # is still an experimental feature.  It is here to stop people
+    # from deploying threads in production. ;-)
+    #
+
+and another known thread-related warning is
+
+   pragma/overload......Unbalanced saves: 3 more saves than restores
+   panic: magic_mutexfree during global destruction.
+   ok
+   lib/selfloader.......Unbalanced saves: 3 more saves than restores
+   panic: magic_mutexfree during global destruction.
+   ok
+   lib/st-dclone........Unbalanced saves: 3 more saves than restores
+   panic: magic_mutexfree during global destruction.
+   ok
+
+=head2 The Compiler Suite Is Still Experimental
+
+The compiler suite is slowly getting better but is nowhere near
+working order yet.  The backend part that has seen perhaps the most
+progress is the bytecode compiler.
+
+=head1 Reporting Bugs
+
+If you find what you think is a bug, you might check the articles
+recently posted to the comp.lang.perl.misc newsgroup and the perl
+bug database at http://bugs.perl.org/  There may also be
+information at http://www.perl.com/perl/ , the Perl Home Page.
+
+If you believe you have an unreported bug, please run the B<perlbug>
+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.
+
+=head1 SEE ALSO
+
+The F<Changes> file for exhaustive details on what changed.
+
+The F<INSTALL> file for how to build Perl.
+
+The F<README> file for general stuff.
+
+The F<Artistic> and F<Copying> files for copyright information.
+
+=head1 HISTORY
+
+Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
+from The Perl Porters and Perl Users submitting feedback and patches.
+
+Send omissions or corrections to <F<perlbug@perl.org>>.
+
+=cut