MirOS Manual: perl58delta(1)


PERL58DELTA(1)  Perl Programmers Reference Guide   PERL58DELTA(1)

NAME

     perl58delta - what is new for perl v5.8.0

DESCRIPTION

     This document describes differences between the 5.6.0
     release and the 5.8.0 release.

     Many of the bug fixes in 5.8.0 were already seen in the
     5.6.1 maintenance release since the two releases were kept
     closely coordinated (while 5.8.0 was still called 5.7.some-
     thing).

     Changes that were integrated into the 5.6.1 release are
     marked "[561]". Many of these changes have been further
     developed since 5.6.1 was released, those are marked
     "[561+]".

     You can see the list of changes in the 5.6.1 release (both
     from the 5.005_03 release and the 5.6.0 release) by reading
     perl561delta.

Highlights In 5.8.0
     +   Better Unicode support

     +   New IO Implementation

     +   New Thread Implementation

     +   Better Numeric Accuracy

     +   Safe Signals

     +   Many New Modules

     +   More Extensive Regression Testing

Incompatible Changes

     Binary Incompatibility

     Perl 5.8 is not binary compatible with earlier releases of
     Perl.

     You have to recompile your XS modules.

     (Pure Perl modules should continue to work.)

     The major reason for the discontinuity is the new IO archi-
     tecture called PerlIO.  PerlIO is the default configuration
     because without it many new features of Perl 5.8 cannot be
     used.  In other words: you just have to recompile your
     modules containing XS code, sorry about that.

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     In future releases of Perl, non-PerlIO aware XS modules may
     become completely unsupported.  This shouldn't be too diffi-
     cult for module authors, however: PerlIO has been designed
     as a drop-in replacement (at the source code level) for the
     stdio interface.

     Depending on your platform, there are also other reasons why
     we decided to break binary compatibility, please read on.

     64-bit platforms and malloc

     If your pointers are 64 bits wide, the Perl malloc is no
     longer being used because it does not work well with 8-byte
     pointers.  Also, usually the system mallocs on such plat-
     forms are much better optimized for such large memory models
     than the Perl malloc.  Some memory-hungry Perl applications
     like the PDL don't work well with Perl's malloc. Finally,
     other applications than Perl (such as mod_perl) tend to
     prefer the system malloc.  Such platforms include Alpha and
     64-bit HPPA, MIPS, PPC, and Sparc.

     AIX Dynaloading

     The AIX dynaloading now uses in AIX releases 4.3 and newer
     the native dlopen interface of AIX instead of the old emu-
     lated interface.  This change will probably break backward
     compatibility with compiled modules.  The change was made to
     make Perl more compliant with other applications like
     mod_perl which are using the AIX native interface.

     Attributes for "my" variables now handled at run-time

     The "my EXPR : ATTRS" syntax now applies variable attributes
     at run-time.  (Subroutine and "our" variables still get
     attributes applied at compile-time.)  See attributes for
     additional details.  In particular, however, this allows
     variable attributes to be useful for "tie" interfaces, which
     was a deficiency of earlier releases.  Note that the new
     semantics doesn't work with the Attribute::Handlers module
     (as of version 0.76).

     Socket Extension Dynamic in VMS

     The Socket extension is now dynamically loaded instead of
     being statically built in.  This may or may not be a problem
     with ancient TCP/IP stacks of VMS: we do not know since we
     weren't able to test Perl in such configurations.

     IEEE-format Floating Point Default on OpenVMS Alpha

     Perl now uses IEEE format (T_FLOAT) as the default internal
     floating point format on OpenVMS Alpha, potentially breaking

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     binary compatibility with external libraries or existing
     data.  G_FLOAT is still available as a configuration option.
     The default on VAX (D_FLOAT) has not changed.

     New Unicode Semantics (no more "use utf8", almost)

     Previously in Perl 5.6 to use Unicode one would say "use
     utf8" and then the operations (like string concatenation)
     were Unicode-aware in that lexical scope.

     This was found to be an inconvenient interface, and in Perl
     5.8 the Unicode model has completely changed: now the
     "Unicodeness" is bound to the data itself, and for most of
     the time "use utf8" is not needed at all.  The only remain-
     ing use of "use utf8" is when the Perl script itself has
     been written in the UTF-8 encoding of Unicode.  (UTF-8 has
     not been made the default since there are many Perl scripts
     out there that are using various national eight-bit charac-
     ter sets, which would be illegal in UTF-8.)

     See perluniintro for the explanation of the current model,
     and utf8 for the current use of the utf8 pragma.

     New Unicode Properties

     Unicode scripts are now supported. Scripts are similar to
     (and superior to) Unicode blocks. The difference between
     scripts and blocks is that scripts are the glyphs used by a
     language or a group of languages, while the blocks are more
     artificial groupings of (mostly) 256 characters based on the
     Unicode numbering.

     In general, scripts are more inclusive, but not universally
     so. For example, while the script "Latin" includes all the
     Latin characters and their various diacritic-adorned ver-
     sions, it does not include the various punctuation or digits
     (since they are not solely "Latin").

     A number of other properties are now supported, including
     "\p{L&}", "\p{Any}" "\p{Assigned}", "\p{Unassigned}",
     "\p{Blank}" [561] and "\p{SpacePerl}" [561] (along with
     their "\P{...}" versions, of course). See perlunicode for
     details, and more additions.

     The "In" or "Is" prefix to names used with the "\p{...}" and
     "\P{...}" are now almost always optional. The only exception
     is that a "In" prefix is required to signify a Unicode block
     when a block name conflicts with a script name. For example,
     "\p{Tibetan}" refers to the script, while "\p{InTibetan}"
     refers to the block. When there is no name conflict, you can
     omit the "In" from the block name (e.g.
     "\p{BraillePatterns}"), but to be safe, it's probably best

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     to always use the "In").

     REF(...) Instead Of SCALAR(...)

     A reference to a reference now stringifies as
     "REF(0x81485ec)" instead of "SCALAR(0x81485ec)" in order to
     be more consistent with the return value of ref().

     pack/unpack D/F recycled

     The undocumented pack/unpack template letters D/F have been
     recycled for better use: now they stand for long double (if
     supported by the platform) and NV (Perl internal floating
     point type).  (They used to be aliases for d/f, but you
     never knew that.)

     glob() now returns filenames in alphabetical order

     The list of filenames from glob() (or <...>) is now by
     default sorted alphabetically to be csh-compliant (which is
     what happened before in most UNIX platforms).  (bsd_glob()
     does still sort platform natively, ASCII or EBCDIC, unless
     GLOB_ALPHASORT is specified.) [561]

     Deprecations

     +   The semantics of bless(REF, REF) were unclear and until
         someone proves it to make some sense, it is forbidden.

     +   The obsolete chat2 library that should never have been
         allowed to escape the laboratory has been decommis-
         sioned.

     +   Using chdir("") or chdir(undef) instead of explicit
         chdir() is doubtful.  A failure (think
         chdir(some_function()) can lead into unintended chdir()
         to the home directory, therefore this behaviour is
         deprecated.

     +   The builtin dump() function has probably outlived most
         of its usefulness.  The core-dumping functionality will
         remain in future available as an explicit call to
         "CORE::dump()", but in future releases the behaviour of
         an unqualified "dump()" call may change.

     +   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 docu-
         mented, tested and (most importantly) maintained.

     +   The (bogus) escape sequences \8 and \9 now give an
         optional warning ("Unrecognized escape passed through").

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         There is no need to \-escape any "\w" character.

     +   The *glob{FILEHANDLE} is deprecated, use *glob{IO}
         instead.

     +   The "package;" syntax ("package" without an argument)
         has been deprecated.  Its semantics were never that
         clear and its implementation even less so.  If you have
         used that feature to disallow all but fully qualified
         variables, "use strict;" instead.

     +   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.

     +   In future releases, non-PerlIO aware XS modules may
         become completely unsupported.  Since PerlIO is a drop-
         in replacement for stdio at the source code level, this
         shouldn't be that drastic a change.

     +   Previous versions of perl and some readings of some sec-
         tions of Camel III implied that the ":raw" "discipline"
         was the inverse of ":crlf". Turning off "clrfness" is no
         longer enough to make a stream truly binary. So the Per-
         lIO ":raw" layer (or "discipline", to use the Camel
         book's older terminology) is now formally defined as
         being equivalent to binmode(FH) - which is in turn
         defined as doing whatever is necessary to pass each byte
         as-is without any translation.  In particular
         binmode(FH) - and hence ":raw" - will now turn off both
         CRLF and UTF-8 translation and remove other layers (e.g.
         :encoding()) which would modify byte stream.

     +   The current user-visible implementation of pseudo-hashes
         (the weird use of the first array element) is deprecated
         starting from Perl 5.8.0 and will be removed in Perl
         5.10.0, and the feature will be implemented differently.
         Not only is the current interface rather ugly, but the
         current implementation slows down normal array and hash
         use quite noticeably. The "fields" pragma interface will
         remain available.  The restricted hashes interface is
         expected to be the replacement interface (see
         Hash::Util).  If your existing programs depends on the
         underlying implementation, consider using
         Class::PseudoHash from CPAN.

     +   The syntaxes "@a->[...]" and  "%h->{...}" have now been
         deprecated.

     +   After years of trying, suidperl is considered to be too

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         complex to ever be considered truly secure.  The suid-
         perl functionality is likely to be removed in a future
         release.

     +   The 5.005 threads model (module "Thread") is deprecated
         and expected to be removed in Perl 5.10.  Multithreaded
         code should be migrated to the new ithreads model (see
         threads, threads::shared and perlthrtut).

     +   The long deprecated uppercase aliases for the string
         comparison operators (EQ, NE, LT, LE, GE, GT) have now
         been removed.

     +   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', ...). [561]

     +   Earlier Perls treated "sub foo (@bar)" as equivalent to
         "sub foo (@)". The prototypes are now checked better at
         compile-time for invalid syntax.  An optional warning is
         generated ("Illegal character in prototype...")  but
         this may be upgraded to a fatal error in a future
         release.

     +   The "exec LIST" and "system LIST" operations now produce
         warnings on tainted data and in some future release they
         will produce fatal errors.

     +   The existing behaviour when localising tied arrays and
         hashes is wrong, and will be changed in a future
         release, so do not rely on the existing behaviour. See
         "Localising Tied Arrays and Hashes Is Broken".

Core Enhancements

     Unicode Overhaul

     Unicode in general should be now much more usable than in
     Perl 5.6.0 (or even in 5.6.1).  Unicode can be used in hash
     keys, Unicode in regular expressions should work now,
     Unicode in tr/// should work now, Unicode in I/O should work
     now.  See perluniintro for introduction and perlunicode for
     details.

     +   The Unicode Character Database coming with Perl has been
         upgraded to Unicode 3.2.0.  For more information, see
         http://www.unicode.org/ . [561+] (5.6.1 has UCD 3.0.1.)

     +   For developers interested in enhancing Perl's Unicode
         capabilities: almost all the UCD files are included with
         the Perl distribution in the lib/unicore subdirectory.
         The most notable omission, for space considerations, is

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         the Unihan database.

     +   The properties \p{Blank} and \p{SpacePerl} have been
         added. "Blank" is like C isblank(), that is, it contains
         only "horizontal whitespace" (the space character is,
         the newline isn't), and the "SpacePerl" is the Unicode
         equivalent of "\s" (\p{Space} isn't, since that includes
         the vertical tabulator character, whereas "\s" doesn't.)

         See "New Unicode Properties" earlier in this document
         for additional information on changes with Unicode pro-
         perties.

     PerlIO is Now The Default

     +   IO is now by default done via PerlIO rather than
         system's "stdio". PerlIO allows "layers" to be "pushed"
         onto a file handle to alter the handle's behaviour.
         Layers can be specified at open time via 3-arg form of
         open:

            open($fh,'>:crlf :utf8', $path) || ...

         or on already opened handles via extended "binmode":

            binmode($fh,':encoding(iso-8859-7)');

         The built-in layers are: unix (low level read/write),
         stdio (as in previous Perls), perlio (re-implementation
         of stdio buffering in a portable manner), crlf (does
         CRLF <=> "\n" translation as on Win32, but available on
         any platform).  A mmap layer may be available if plat-
         form supports it (mostly UNIXes).

         Layers to be applied by default may be specified via the
         'open' pragma.

         See "Installation and Configuration Improvements" for
         the effects of PerlIO on your architecture name.

     +   If your platform supports fork(), you can use the list
         form of "open" for pipes.  For example:

             open KID_PS, "-|", "ps", "aux" or die $!;

         forks the ps(1) command (without spawning a shell, as
         there are more than three arguments to open()), and
         reads its standard output via the "KID_PS" filehandle.
         See perlipc.

     +   File handles can be marked as accepting Perl's internal
         encoding of Unicode (UTF-8 or UTF-EBCDIC depending on

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         platform) by a pseudo layer ":utf8" :

            open($fh,">:utf8","Uni.txt");

         Note for EBCDIC users: the pseudo layer ":utf8" is
         erroneously named for you since it's not UTF-8 what you
         will be getting but instead UTF-EBCDIC.  See perlun-
         icode, utf8, and
         http://www.unicode.org/unicode/reports/tr16/ for more
         information. In future releases this naming may change.
         See perluniintro for more information about UTF-8.

     +   If your environment variables (LC_ALL, LC_CTYPE, LANG)
         look like you want to use UTF-8 (any of the variables
         match "/utf-?8/i"), your STDIN, STDOUT, STDERR handles
         and the default open layer (see open) are marked as
         UTF-8.  (This feature, like other new features that com-
         bine Unicode and I/O, work only if you are using PerlIO,
         but that's the default.)

         Note that after this Perl really does assume that every-
         thing is UTF-8: for example if some input handle is not,
         Perl will probably very soon complain about the input
         data like this "Malformed UTF-8 ..." since any old
         eight-bit data is not legal UTF-8.

         Note for code authors: if you want to enable your users
         to use UTF-8 as their default encoding  but in your code
         still have eight-bit I/O streams (such as images or zip
         files), you need to explicitly open() or binmode() with
         ":bytes" (see "open" in perlfunc and "binmode" in perl-
         func), or you can just use "binmode(FH)" (nice for
         pre-5.8.0 backward compatibility).

     +   File handles can translate character encodings from/to
         Perl's internal Unicode form on read/write via the
         ":encoding()" layer.

     +   File handles can be opened to "in memory" files held in
         Perl scalars via:

            open($fh,'>', \$variable) || ...

     +   Anonymous temporary files are available without need to
         'use FileHandle' or other module via

            open($fh,"+>", undef) || ...

         That is a literal undef, not an undefined value.

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     ithreads

     The new interpreter threads ("ithreads" for short) implemen-
     tation of multithreading, by Arthur Bergman, replaces the
     old "5.005 threads" implementation.  In the ithreads model
     any data sharing between threads must be explicit, as
     opposed to the model where data sharing was implicit.  See
     threads and threads::shared, and perlthrtut.

     As a part of the ithreads implementation Perl will also use
     any necessary and detectable reentrant libc interfaces.

     Restricted Hashes

     A restricted hash is restricted to a certain set of keys, no
     keys outside the set can be added.  Also individual keys can
     be restricted so that the key cannot be deleted and the
     value cannot be changed. No new syntax is involved: the
     Hash::Util module is the interface.

     Safe Signals

     Perl used to be fragile in that signals arriving at inoppor-
     tune moments could corrupt Perl's internal state.  Now Perl
     postpones handling of signals until it's safe (between
     opcodes).

     This change may have surprising side effects because signals
     no longer interrupt Perl instantly.  Perl will now first
     finish whatever it was doing, like finishing an internal
     operation (like sort()) or an external operation (like an
     I/O operation), and only then look at any arrived signals
     (and before starting the next operation).  No more corrupt
     internal state since the current operation is always fin-
     ished first, but the signal may take more time to get heard.
     Note that breaking out from potentially blocking operations
     should still work, though.

     Understanding of Numbers

     In general a lot of fixing has happened in the area of
     Perl's understanding of numbers, both integer and floating
     point.  Since in many systems the standard number parsing
     functions like "strtoul()" and "atof()" seem to have bugs,
     Perl tries to work around their deficiencies.  This results
     hopefully in more accurate numbers.

     Perl now tries internally to use integer values in numeric
     conversions and basic arithmetics (+ - * /) if the arguments
     are integers, and tries also to keep the results stored
     internally as integers. This change leads to often slightly
     faster and always less lossy arithmetics. (Previously Perl

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     always preferred floating point numbers in its math.)

     Arrays now always interpolate into double-quoted strings
     [561]

     In double-quoted strings, arrays now interpolate, no matter
     what.  The behavior in earlier versions of perl 5 was that
     arrays would interpolate into strings if the array had been
     mentioned before the string was compiled, and otherwise Perl
     would raise a fatal compile-time error. In versions 5.000
     through 5.003, the error was

             Literal @example now requires backslash

     In versions 5.004_01 through 5.6.0, the error was

             In string, @example now must be written as \@example

     The idea here was to get people into the habit of writing
     "fred\@example.com" when they wanted a literal "@" sign,
     just as they have always written "Give me back my \$5" when
     they wanted a literal "$" sign.

     Starting with 5.6.1, when Perl now sees an "@" sign in a
     double-quoted string, it always attempts to interpolate an
     array, regardless of whether or not the array has been used
     or declared already.  The fatal error has been downgraded to
     an optional warning:

             Possible unintended interpolation of @example in string

     This warns you that "fred@example.com" is going to turn into
     "fred.com" if you don't backslash the "@". See
     http://www.plover.com/~mjd/perl/at-error.html for more
     details about the history here.

     Miscellaneous Changes

     +   AUTOLOAD is now lvaluable, meaning that you can add the
         :lvalue attribute to AUTOLOAD subroutines and you can
         assign to the AUTOLOAD return value.

     +   The $Config{byteorder} (and corresponding BYTEORDER in
         config.h) was previously wrong in platforms if
         sizeof(long) was 4, but sizeof(IV) was 8.  The byteorder
         was only sizeof(long) bytes long (1234 or 4321), but now
         it is correctly sizeof(IV) bytes long, (12345678 or
         87654321). (This problem didn't affect Windows plat-
         forms.)

         Also, $Config{byteorder} is now computed dynamically--
         this is more robust with "fat binaries" where an

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         executable image contains binaries for more than one
         binary platform, and when cross-compiling.

     +   "perl -d:Module=arg,arg,arg" now works (previously one
         couldn't pass in multiple arguments.)

     +   "do" followed by a bareword now ensures that this bare-
         word isn't a keyword (to avoid a bug where "do
         q(foo.pl)" tried to call a subroutine called "q").  This
         means that for example instead of "do format()" you must
         write "do &format()".

     +   The builtin dump() now gives an optional warning "dump()
         better written as CORE::dump()", meaning that by default
         "dump(...)" is resolved as the builtin dump() which
         dumps core and aborts, not as (possibly) user-defined
         "sub dump".  To call the latter, qualify the call as
         "&dump(...)". (The whole dump() feature is to considered
         deprecated, and possibly removed/changed in future
         releases.)

     +   chomp() and chop() are now overridable.  Note, however,
         that their prototype (as given by
         "prototype("CORE::chomp")" is undefined, because it can-
         not be expressed and therefore one cannot really write
         replacements to override these builtins.

     +   END blocks are now run even if you exit/die in a BEGIN
         block. Internally, the execution of END blocks is now
         controlled by PL_exit_flags & PERL_EXIT_DESTRUCT_END.
         This enables the new behaviour for Perl embedders. This
         will default in 5.10. See perlembed.

     +   Formats now support zero-padded decimal fields.

     +   Although "you shouldn't do that", it was possible to
         write code that depends on Perl's hashed key order
         (Data::Dumper does this).  The new algorithm
         "One-at-a-Time" produces a different hashed key order.
         More details are in "Performance Enhancements".

     +   lstat(FILEHANDLE) now gives a warning because the opera-
         tion makes no sense. In future releases this may become
         a fatal error.

     +   Spurious syntax errors generated in certain situations,
         when glob() caused File::Glob to be loaded for the first
         time, have been fixed. [561]

     +   Lvalue subroutines can now return "undef" in list con-
         text.  However, the lvalue subroutine feature still
         remains experimental.  [561+]

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     +   A lost warning "Can't declare ... dereference in my" has
         been restored (Perl had it earlier but it became lost in
         later releases.)

     +   A new special regular expression variable has been
         introduced: $^N, which contains the most-recently closed
         group (submatch).

     +   "no Module;" does not produce an error even if Module
         does not have an unimport() method.  This parallels the
         behavior of "use" vis-a-vis "import". [561]

     +   The numerical comparison operators return "undef" if
         either operand is a NaN.  Previously the behaviour was
         unspecified.

     +   "our" can now have an experimental optional attribute
         "unique" that affects how global variables are shared
         among multiple interpreters, see "our" in perlfunc.

     +   The following builtin functions are now overridable:
         each(), keys(), pop(), push(), shift(), splice(),
         unshift(). [561]

     +   "pack() / unpack()" can now group template letters with
         "()" and then apply repetition/count modifiers on the
         groups.

     +   "pack() / unpack()" can now process the Perl internal
         numeric types: IVs, UVs, NVs-- and also long doubles, if
         supported by the platform. The template letters are "j",
         "J", "F", and "D".

     +   "pack('U0a*', ...)" can now be used to force a string to
         UTF-8.

     +   my __PACKAGE__ $obj now works. [561]

     +   POSIX::sleep() now returns the number of unslept seconds
         (as the POSIX standard says), as opposed to
         CORE::sleep() which returns the number of slept seconds.

     +   printf() and sprintf() now support parameter reordering
         using the "%\d+\$" and "*\d+\$" syntaxes.  For example

             printf "%2\$s %1\$s\n", "foo", "bar";

         will print "bar foo\n".  This feature helps in writing
         internationalised software, and in general when the
         order of the parameters can vary.

     +   The (\&) prototype now works properly. [561]

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     +   prototype(\[$@%&]) is now available to implicitly create
         references (useful for example if you want to emulate
         the tie() interface).

     +   A new command-line option, "-t" is available.  It is the
         little brother of "-T": instead of dying on taint viola-
         tions, lexical warnings are given.  This is only meant
         as a temporary debugging aid while securing the code of
         old legacy applications. This is not a substitute for
         -T.

     +   In other taint news, the "exec LIST" and "system LIST"
         have now been considered too risky (think "exec @ARGV":
         it can start any program with any arguments), and now
         the said forms cause a warning under lexical warnings.
         You should carefully launder the arguments to guarantee
         their validity.  In future releases of Perl the forms
         will become fatal errors so consider starting laundering
         now.

     +   Tied hash interfaces are now required to have the EXISTS
         and DELETE methods (either own or inherited).

     +   If tr/// is just counting characters, it doesn't attempt
         to modify its target.

     +   untie() will now call an UNTIE() hook if it exists.  See
         perltie for details. [561]

     +   utime now supports "utime undef, undef, @files" to
         change the file timestamps to the current time.

     +   The rules for allowing underscores (underbars) in
         numeric constants have been relaxed and simplified: now
         you can have an underscore simply between digits.

     +   Rather than relying on C's argv[0] (which may not con-
         tain a full pathname) where possible $^X is now set by
         asking the operating system. (eg by reading
         /proc/self/exe on Linux, /proc/curproc/file on FreeBSD)

     +   A new variable, "${^TAINT}", indicates whether taint
         mode is enabled.

     +   You can now override the readline() builtin, and this
         overrides also the <FILEHANDLE> angle bracket operator.

     +   The command-line options -s and -F are now recognized on
         the shebang (#!) line.

     +   Use of the "/c" match modifier without an accompanying
         "/g" modifier elicits a new warning: "Use of /c modifier

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         is meaningless without /g".

         Use of "/c" in substitutions, even with "/g", elicits
         "Use of /c modifier is meaningless in s///".

         Use of "/g" with "split" elicits "Use of /g modifier is
         meaningless in split".

     +   Support for the "CLONE" special subroutine had been
         added. With ithreads, when a new thread is created, all
         Perl data is cloned, however non-Perl data cannot be
         cloned automatically.  In "CLONE" you can do whatever
         you need to do, like for example handle the cloning of
         non-Perl data, if necessary.  "CLONE" will be executed
         once for every package that has it defined or inherited.
         It will be called in the context of the new thread, so
         all modifications are made in the new area.

         See perlmod

Modules and Pragmata

     New Modules and Pragmata

     +   "Attribute::Handlers", originally by Damian Conway and
         now maintained by Arthur Bergman, allows a class to
         define attribute handlers.

             package MyPack;
             use Attribute::Handlers;
             sub Wolf :ATTR(SCALAR) { print "howl!\n" }

             # later, in some package using or inheriting from MyPack...

             my MyPack $Fluffy : Wolf; # the attribute handler Wolf will be called

         Both variables and routines can have attribute handlers.
         Handlers can be specific to type (SCALAR, ARRAY, HASH,
         or CODE), or specific to the exact compilation phase
         (BEGIN, CHECK, INIT, or END). See Attribute::Handlers.

     +   "B::Concise", by Stephen McCamant, is a new compiler
         backend for walking the Perl syntax tree, printing con-
         cise info about ops. The output is highly customisable.
         See B::Concise. [561+]

     +   The new bignum, bigint, and bigrat pragmas, by Tels,
         implement transparent bignum support (using the
         Math::BigInt, Math::BigFloat, and Math::BigRat back-
         ends).

     +   "Class::ISA", by Sean Burke, is a module for reporting
         the search path for a class's ISA tree.  See Class::ISA.

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     +   "Cwd" now has a split personality: if possible, an XS
         extension is used, (this will hopefully be faster, more
         secure, and more robust) but if not possible, the fami-
         liar Perl implementation is used.

     +   "Devel::PPPort", originally by Kenneth Albanowski and
         now maintained by Paul Marquess, has been added.  It is
         primarily used by "h2xs" to enhance portability of XS
         modules between different versions of Perl.  See
         Devel::PPPort.

     +   "Digest", frontend module for calculating digests
         (checksums), from Gisle Aas, has been added.  See Dig-
         est.

     +   "Digest::MD5" for calculating MD5 digests (checksums) as
         defined in RFC 1321, from Gisle Aas, has been added.
         See Digest::MD5.

             use Digest::MD5 'md5_hex';

             $digest = md5_hex("Thirsty Camel");

             print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1

         NOTE: the "MD5" backward compatibility module is deli-
         berately not included since its further use is
         discouraged.

         See also PerlIO::via::QuotedPrint.

     +   "Encode", originally by Nick Ing-Simmons and now main-
         tained by Dan Kogai, provides a mechanism to translate
         between different character encodings.  Support for
         Unicode, ISO-8859-1, and ASCII are compiled in to the
         module.  Several other encodings (like the rest of the
         ISO-8859, CP*/Win*, Mac, KOI8-R, three variants EBCDIC,
         Chinese, Japanese, and Korean encodings) are included
         and can be loaded at runtime.  (For space considera-
         tions, the largest Chinese encodings have been separated
         into their own CPAN module, Encode::HanExtra, which
         Encode will use if available).  See Encode.

         Any encoding supported by Encode module is also avail-
         able to the ":encoding()" layer if PerlIO is used.

     +   "Hash::Util" is the interface to the new restricted
         hashes feature.  (Implemented by Jeffrey Friedl, Nick
         Ing-Simmons, and Michael Schwern.)  See Hash::Util.

     +   "I18N::Langinfo" can be used to query locale informa-
         tion. See I18N::Langinfo.

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     +   "I18N::LangTags", by Sean Burke, has functions for deal-
         ing with RFC3066-style language tags.  See
         I18N::LangTags.

     +   "ExtUtils::Constant", by Nicholas Clark, is a new tool
         for extension writers for generating XS code to import C
         header constants. See ExtUtils::Constant.

     +   "Filter::Simple", by Damian Conway, is an easy-to-use
         frontend to Filter::Util::Call.  See Filter::Simple.

             # in MyFilter.pm:

             package MyFilter;

             use Filter::Simple sub {
                 while (my ($from, $to) = splice @_, 0, 2) {
                         s/$from/$to/g;
                 }
             };

             1;

             # in user's code:

             use MyFilter qr/red/ => 'green';

             print "red\n";   # this code is filtered, will print "green\n"
             print "bored\n"; # this code is filtered, will print "bogreen\n"

             no MyFilter;

             print "red\n";   # this code is not filtered, will print "red\n"

     +   "File::Temp", by Tim Jenness, allows one to create tem-
         porary files and directories in an easy, portable, and
         secure way.  See File::Temp. [561+]

     +   "Filter::Util::Call", by Paul Marquess, provides you
         with the framework to write source filters in Perl.  For
         most uses, the frontend Filter::Simple is to be pre-
         ferred.  See Filter::Util::Call.

     +   "if", by Ilya Zakharevich, is a new pragma for condi-
         tional inclusion of modules.

     +   libnet, by Graham Barr, is a collection of perl5 modules
         related to network programming.  See Net::FTP,
         Net::NNTP, Net::Ping (not part of libnet, but related),
         Net::POP3, Net::SMTP, and Net::Time.

         Perl installation leaves libnet unconfigured; use

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         libnetcfg to configure it.

     +   "List::Util", by Graham Barr, is a selection of
         general-utility list subroutines, such as sum(), min(),
         first(), and shuffle(). See List::Util.

     +   "Locale::Constants", "Locale::Country",
         "Locale::Currency" "Locale::Language", and
         Locale::Script, by Neil Bowers, have been added.  They
         provide the codes for various locale standards, such as
         "fr" for France, "usd" for US Dollar, and "ja" for
         Japanese.

             use Locale::Country;

             $country = code2country('jp');               # $country gets 'Japan'
             $code    = country2code('Norway');           # $code gets 'no'

         See Locale::Constants, Locale::Country,
         Locale::Currency, and Locale::Language.

     +   "Locale::Maketext", by Sean Burke, is a localization
         framework.  See Locale::Maketext, and
         Locale::Maketext::TPJ13.  The latter is an article about
         software localization, originally published in The Perl
         Journal #13, and republished here with kind permission.

     +   "Math::BigRat" for big rational numbers, to accompany
         Math::BigInt and Math::BigFloat, from Tels.  See
         Math::BigRat.

     +   "Memoize" can make your functions faster by trading
         space for time, from Mark-Jason Dominus.  See Memoize.

     +   "MIME::Base64", by Gisle Aas, allows you to encode data
         in base64, as defined in RFC 2045 - MIME (Multipurpose
         Internet Mail Extensions).

             use MIME::Base64;

             $encoded = encode_base64('Aladdin:open sesame');
             $decoded = decode_base64($encoded);

             print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="

         See MIME::Base64.

     +   "MIME::QuotedPrint", by Gisle Aas, allows you to encode
         data in quoted-printable encoding, as defined in RFC
         2045 - MIME (Multipurpose Internet Mail Extensions).

             use MIME::QuotedPrint;

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             $encoded = encode_qp("\xDE\xAD\xBE\xEF");
             $decoded = decode_qp($encoded);

             print $encoded, "\n"; # "=DE=AD=BE=EF\n"
             print $decoded, "\n"; # "\xDE\xAD\xBE\xEF\n"

         See also PerlIO::via::QuotedPrint.

     +   "NEXT", by Damian Conway, is a pseudo-class for method
         redispatch. See NEXT.

     +   "open" is a new pragma for setting the default I/O
         layers for open().

     +   "PerlIO::scalar", by Nick Ing-Simmons, provides the
         implementation of IO to "in memory" Perl scalars as dis-
         cussed above.  It also serves as an example of a load-
         able PerlIO layer.  Other future possibilities include
         PerlIO::Array and PerlIO::Code.  See PerlIO::scalar.

     +   "PerlIO::via", by Nick Ing-Simmons, acts as a PerlIO
         layer and wraps PerlIO layer functionality provided by a
         class (typically implemented in Perl code).

     +   "PerlIO::via::QuotedPrint", by Elizabeth Mattijsen, is
         an example of a "PerlIO::via" class:

             use PerlIO::via::QuotedPrint;
             open($fh,">:via(QuotedPrint)",$path);

         This will automatically convert everything output to $fh
         to Quoted-Printable.  See PerlIO::via and
         PerlIO::via::QuotedPrint.

     +   "Pod::ParseLink", by Russ Allbery, has been added, to
         parse L<> links in pods as described in the new perl-
         podspec.

     +   "Pod::Text::Overstrike", by Joe Smith, has been added.
         It converts POD data to formatted overstrike text. See
         Pod::Text::Overstrike. [561+]

     +   "Scalar::Util" is a selection of general-utility scalar
         subroutines, such as blessed(), reftype(), and
         tainted().  See Scalar::Util.

     +   "sort" is a new pragma for controlling the behaviour of
         sort().

     +   "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.  Because

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         in effect Storable does serialisation of Perl data
         structures, with it you can also clone deep, hierarchi-
         cal datastructures.  Storable was originally created by
         Raphael Manfredi, but it is now maintained by Abhijit
         Menon-Sen.  Storable has been enhanced to understand the
         two new hash features, Unicode keys and restricted
         hashes.  See Storable.

     +   "Switch", by Damian Conway, has been added.  Just by
         saying

             use Switch;

         you have "switch" and "case" available in Perl.

             use Switch;

             switch ($val) {

                         case 1          { print "number 1" }
                         case "a"        { print "string a" }
                         case [1..10,42] { print "number in list" }
                         case (@array)   { print "number in list" }
                         case /\w+/      { print "pattern" }
                         case qr/\w+/    { print "pattern" }
                         case (%hash)    { print "entry in hash" }
                         case (\%hash)   { print "entry in hash" }
                         case (\&sub)    { print "arg to subroutine" }
                         else            { print "previous case not true" }
             }

         See Switch.

     +   "Test::More", by Michael Schwern, is yet another frame-
         work for writing test scripts, more extensive than
         Test::Simple.  See Test::More.

     +   "Test::Simple", by Michael Schwern, has basic utilities
         for writing tests.   See Test::Simple.

     +   "Text::Balanced", by Damian Conway, has been added, for
         extracting delimited text sequences from strings.

             use Text::Balanced 'extract_delimited';

             ($a, $b) = extract_delimited("'never say never', he never said", "'", '');

         $a will be "'never say never'", $b will be ', he never
         said'.

         In addition to extract_delimited(), there are also
         extract_bracketed(), extract_quotelike(),

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         extract_codeblock(), extract_variable(),
         extract_tagged(), extract_multiple(),
         gen_delimited_pat(), and gen_extract_tagged().  With
         these, you can implement rather advanced parsing algo-
         rithms.  See Text::Balanced.

     +   "threads", by Arthur Bergman, is an interface to inter-
         preter threads. Interpreter threads (ithreads) is the
         new thread model introduced in Perl 5.6 but only avail-
         able as an internal interface for extension writers (and
         for Win32 Perl for "fork()" emulation).  See threads,
         threads::shared, and perlthrtut.

     +   "threads::shared", by Arthur Bergman, allows data shar-
         ing for interpreter threads.  See threads::shared.

     +   "Tie::File", by Mark-Jason Dominus, associates a Perl
         array with the lines of a file.  See Tie::File.

     +   "Tie::Memoize", by Ilya Zakharevich, provides on-demand
         loaded hashes. See Tie::Memoize.

     +   "Tie::RefHash::Nestable", by Edward Avis, allows storing
         hash references (unlike the standard Tie::RefHash)  The
         module is contained within Tie::RefHash.  See
         Tie::RefHash.

     +   "Time::HiRes", by Douglas E. Wegscheid, provides high
         resolution timing (ualarm, usleep, and gettimeofday).
         See Time::HiRes.

     +   "Unicode::UCD" offers a querying interface to the
         Unicode Character Database.  See Unicode::UCD.

     +   "Unicode::Collate", by SADAHIRO Tomoyuki, implements the
         UCA (Unicode Collation Algorithm) for sorting Unicode
         strings. See Unicode::Collate.

     +   "Unicode::Normalize", by SADAHIRO Tomoyuki, implements
         the various Unicode normalization forms.  See
         Unicode::Normalize.

     +   "XS::APItest", by Tim Jenness, is a test extension that
         exercises XS APIs.  Currently only "printf()" is tested:
         how to output various basic data types from XS.

     +   "XS::Typemap", by Tim Jenness, is a test extension that
         exercises XS typemaps.  Nothing gets installed, but the
         code is worth studying for extension writers.

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     Updated And Improved Modules and Pragmata

     +   The following independently supported modules have been
         updated to the newest versions from CPAN: CGI, CPAN,
         DB_File, File::Spec, File::Temp, Getopt::Long,
         Math::BigFloat, Math::BigInt, the podlators bundle
         (Pod::Man, Pod::Text), Pod::LaTeX [561+], Pod::Parser,
         Storable, Term::ANSIColor, Test, Text-Tabs+Wrap.

     +   attributes::reftype() now works on tied arguments.

     +   AutoLoader can now be disabled with "no AutoLoader;".

     +   B::Deparse has been significantly enhanced by Robin
         Houston.  It can now deparse almost all of the standard
         test suite (so that the tests still succeed).  There is
         a make target "test.deparse" for trying this out.

     +   Carp now has better interface documentation, and the
         @CARP_NOT interface has been added to get optional con-
         trol over where errors are reported independently of
         @ISA, by Ben Tilly.

     +   Class::Struct can now define the classes in compile
         time.

     +   Class::Struct now assigns the array/hash element if the
         accessor is called with an array/hash element as the
         sole argument.

     +   The return value of Cwd::fastcwd() is now tainted.

     +   Data::Dumper now has an option to sort hashes.

     +   Data::Dumper now has an option to dump code references
         using B::Deparse.

     +   DB_File now supports newer Berkeley DB versions, among
         other improvements.

     +   Devel::Peek now has an interface for the Perl memory
         statistics (this works only if you are using perl's mal-
         loc, and if you have compiled with debugging).

     +   The English module can now be used without the infamous
         performance hit by saying

                 use English '-no_match_vars';

         (Assuming, of course, that you don't need the trouble-
         some variables $`, $&, or $'.)  Also, introduced
         @LAST_MATCH_START and @LAST_MATCH_END English aliases

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         for "@-" and "@+".

     +   ExtUtils::MakeMaker has been significantly cleaned up
         and fixed. The enhanced version has also been backported
         to earlier releases of Perl and submitted to CPAN so
         that the earlier releases can enjoy the fixes.

     +   The arguments of WriteMakefile() in Makefile.PL are now
         checked for sanity much more carefully than before.
         This may cause new warnings when modules are being
         installed.  See ExtUtils::MakeMaker for more details.

     +   ExtUtils::MakeMaker now uses File::Spec internally,
         which hopefully leads to better portability.

     +   Fcntl, Socket, and Sys::Syslog have been rewritten by
         Nicholas Clark to use the new-style constant dispatch
         section (see ExtUtils::Constant). This means that they
         will be more robust and hopefully faster.

     +   File::Find now chdir()s correctly when chasing symbolic
         links. [561]

     +   File::Find now has pre- and post-processing callbacks.
         It also correctly changes directories when chasing sym-
         bolic links.  Callbacks (naughtily) exiting with "next;"
         instead of "return;" now work.

     +   File::Find is now (again) reentrant.  It also has been
         made more portable.

     +   The warnings issued by File::Find now belong to their
         own category. You can enable/disable them with "use/no
         warnings 'File::Find';".

     +   File::Glob::glob() has been renamed to
         File::Glob::bsd_glob() because the name clashes with the
         builtin glob().  The older name is still available for
         compatibility, but is deprecated. [561]

     +   File::Glob now supports "GLOB_LIMIT" constant to limit
         the size of the returned list of filenames.

     +   IPC::Open3 now allows the use of numeric file descrip-
         tors.

     +   IO::Socket now has an atmark() method, which returns
         true if the socket is positioned at the out-of-band
         mark.  The method is also exportable as a sockatmark()
         function.

     +   IO::Socket::INET failed to open the specified port if

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         the service name was not known.  It now correctly uses
         the supplied port number as is. [561]

     +   IO::Socket::INET has support for the ReusePort option
         (if your platform supports it).  The Reuse option now
         has an alias, ReuseAddr. For clarity, you may want to
         prefer ReuseAddr.

     +   IO::Socket::INET now supports a value of zero for
         "LocalPort" (usually meaning that the operating system
         will make one up.)

     +   'use lib' now works identically to @INC.  Removing
         directories with 'no lib' now works.

     +   Math::BigFloat and Math::BigInt have undergone a full
         rewrite by Tels. They are now magnitudes faster, and
         they support various bignum libraries such as GMP and
         PARI as their backends.

     +   Math::Complex handles inf, NaN etc., better.

     +   Net::Ping has been considerably enhanced by Rob Brown:
         multihoming is now supported, Win32 functionality is
         better, there is now time measuring functionality
         (optionally high-resolution using Time::HiRes), and
         there is now "external" protocol which uses
         Net::Ping::External module which runs your external ping
         utility and parses the output.  A version of
         Net::Ping::External is available in CPAN.

         Note that some of the Net::Ping tests are disabled when
         running under the Perl distribution since one cannot
         assume one or more of the following: enabled echo port
         at localhost, full Internet connectivity, or sympathetic
         firewalls.  You can set the environment variable
         PERL_TEST_Net_Ping to "1" (one) before running the Perl
         test suite to enable all the Net::Ping tests.

     +   POSIX::sigaction() is now much more flexible and robust.
         You can now install coderef handlers, 'DEFAULT', and
         'IGNORE' handlers, installing new handlers was not
         atomic.

     +   In Safe, %INC is now localised in a Safe compartment so
         that use/require work.

     +   In SDBM_File on dosish platforms, some keys went missing
         because of lack of support for files with "holes".  A
         workaround for the problem has been added.

     +   In Search::Dict one can now have a pre-processing hook

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         for the lines being searched.

     +   The Shell module now has an OO interface.

     +   In Sys::Syslog there is now a failover mechanism that
         will go through alternative connection mechanisms until
         the message is successfully logged.

     +   The Test module has been significantly enhanced.

     +   Time::Local::timelocal() does not handle fractional
         seconds anymore. The rationale is that neither does
         localtime(), and timelocal() and localtime() are sup-
         posed to be inverses of each other.

     +   The vars pragma now supports declaring fully qualified
         variables. (Something that "our()" does not and will not
         support.)

     +   The "utf8::" name space (as in the pragma) provides
         various Perl-callable functions to provide low level
         access to Perl's internal Unicode representation.  At
         the moment only length() has been implemented.

Utility Changes

     +   Emacs perl mode (emacs/cperl-mode.el) has been updated
         to version 4.31.

     +   emacs/e2ctags.pl is now much faster.

     +   "enc2xs" is a tool for people adding their own encodings
         to the Encode module.

     +   "h2ph" now supports C trigraphs.

     +   "h2xs" now produces a template README.

     +   "h2xs" now uses "Devel::PPPort" for better portability
         between different versions of Perl.

     +   "h2xs" uses the new ExtUtils::Constant module which will
         affect newly created extensions that define constants.
         Since the new code is more correct (if you have two con-
         stants where the first one is a prefix of the second
         one, the first constant never got defined), less lossy
         (it uses integers for integer constant, as opposed to
         the old code that used floating point numbers even for
         integer constants), and slightly faster, you might want
         to consider regenerating your extension code (the new
         scheme makes regenerating easy).  h2xs now also supports
         C trigraphs.

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     +   "libnetcfg" has been added to configure libnet.

     +   "perlbug" is now much more robust.  It also sends the
         bug report to perl.org, not perl.com.

     +   "perlcc" has been rewritten and its user interface (that
         is, command line) is much more like that of the UNIX C
         compiler, cc. (The perlbc tools has been removed.  Use
         "perlcc -B" instead.) Note that perlcc is still con-
         sidered very experimental and unsupported. [561]

     +   "perlivp" is a new Installation Verification Procedure
         utility for running any time after installing Perl.

     +   "piconv" is an implementation of the character conver-
         sion utility "iconv", demonstrating the new Encode
         module.

     +   "pod2html" now allows specifying a cache directory.

     +   "pod2html" now produces XHTML 1.0.

     +   "pod2html" now understands POD written using different
         line endings (PC-like CRLF versus UNIX-like LF versus
         MacClassic-like CR).

     +   "s2p" has been completely rewritten in Perl.  (It is in
         fact a full implementation of sed in Perl: you can use
         the sed functionality by using the "psed" utility.)

     +   "xsubpp" now understands POD documentation embedded in
         the *.xs files. [561]

     +   "xsubpp" now supports the OUT keyword.

New Documentation

     +   perl56delta details the changes between the 5.005
         release and the 5.6.0 release.

     +   perlclib documents the internal replacements for stan-
         dard C library functions.  (Interesting only for exten-
         sion writers and Perl core hackers.) [561+]

     +   perldebtut is a Perl debugging tutorial. [561+]

     +   perlebcdic contains considerations for running Perl on
         EBCDIC platforms. [561+]

     +   perlintro is a gentle introduction to Perl.

     +   perliol documents the internals of PerlIO with layers.

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     +   perlmodstyle is a style guide for writing modules.

     +   perlnewmod tells about writing and submitting a new
         module. [561+]

     +   perlpacktut is a pack() tutorial.

     +   perlpod has been rewritten to be clearer and to record
         the best practices gathered over the years.

     +   perlpodspec is a more formal specification of the pod
         format, mainly of interest for writers of pod applica-
         tions, not to people writing in pod.

     +   perlretut is a regular expression tutorial. [561+]

     +   perlrequick is a regular expressions quick-start guide.
         Yes, much quicker than perlretut. [561]

     +   perltodo has been updated.

     +   perltootc has been renamed as perltooc (to not to con-
         flict with perltoot in filesystems restricted to "8.3"
         names).

     +   perluniintro is an introduction to using Unicode in
         Perl. (perlunicode is more of a detailed reference and
         background information)

     +   perlutil explains the command line utilities packaged
         with the Perl distribution. [561+]

     The following platform-specific documents are available
     before the installation as README.platform, and after the
     installation as perlplatform:

         perlaix perlamiga perlapollo perlbeos perlbs2000
         perlce perlcygwin perldgux perldos perlepoc perlfreebsd perlhpux
         perlhurd perlirix perlmachten perlmacos perlmint perlmpeix
         perlnetware perlos2 perlos390 perlplan9 perlqnx perlsolaris
         perltru64 perluts perlvmesa perlvms perlvos perlwin32

     These documents usually detail one or more of the following
     subjects: configuring, building, testing, installing, and
     sometimes also using Perl on the said platform.

     Eastern Asian Perl users are now welcomed in their own
     languages: README.jp (Japanese), README.ko (Korean),
     README.cn (simplified Chinese) and README.tw (traditional
     Chinese), which are written in normal pod but encoded in
     EUC-JP, EUC-KR, EUC-CN and Big5.  These will get installed
     as

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        perljp perlko perlcn perltw

     +   The documentation for the POSIX-BC platform is called
         "BS2000", to avoid confusion with the Perl POSIX module.

     +   The documentation for the WinCE platform is called
         perlce (README.ce in the source code kit), to avoid con-
         fusion with the perlwin32 documentation on 8.3-res-
         tricted filesystems.

Performance Enhancements

     +   map() could get pathologically slow when the result list
         it generates is larger than the source list.  The per-
         formance has been improved for common scenarios. [561]

     +   sort() is also fully reentrant, in the sense that the
         sort function can itself call sort().  This did not work
         reliably in previous releases. [561]

     +   sort() has been changed to use primarily 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).  See the "sort" pragma for informa-
         tion.

         The story in more detail: suppose you want to serve
         yourself a little slice of Pi.

             @digits = ( 3,1,4,1,5,9 );

         A numerical sort of the digits will yield (1,1,3,4,5,9),
         as expected. Which 1 comes first is hard to know, since
         one 1 looks pretty much like any other.  You can regard
         this as totally trivial, or somewhat profound.  However,
         if you just want to sort the even digits ahead of the
         odd ones, then what will

             sort { ($a % 2) <=> ($b % 2) } @digits;

         yield?  The only even digit, 4, will come first.  But
         how about the odd numbers, which all compare equal?
         With the quicksort algorithm used to implement Perl 5.6
         and earlier, the order of ties is left up to the sort.
         So, as you add more and more digits of Pi, the order in
         which the sorted even and odd digits appear will change.

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         and, for sufficiently large slices of Pi, the quicksort
         algorithm in Perl 5.8 won't return the same results even
         if reinvoked with the same input.  The justification for
         this rests with quicksort's worst case behavior.  If you
         run

            sort { $a <=> $b } ( 1 .. $N , 1 .. $N );

         (something you might approximate if you wanted to merge
         two sorted arrays using sort), doubling $N doesn't just
         double the quicksort time, it quadruples it.  Quicksort
         has a worst case run time that can grow like N**2, so-
         called quadratic behaviour, and it can happen on pat-
         terns that may well arise in normal use.  You won't
         notice this for small arrays, but you will notice it
         with larger arrays, and you may not live long enough for
         the sort to complete on arrays of a million elements.
         So the 5.8 quicksort scrambles large arrays before sort-
         ing them, as a statistical defence against quadratic
         behaviour. But that means if you sort the same large
         array twice, ties may be broken in different ways.

         Because of the unpredictability of tie-breaking order,
         and the quadratic worst-case behaviour, quicksort was
         almost replaced completely with a stable mergesort.
         Stable means that ties are broken to preserve the origi-
         nal order of appearance in the input array.  So

             sort { ($a % 2) <=> ($b % 2) } (3,1,4,1,5,9);

         will yield (4,3,1,1,5,9), guaranteed.  The even and odd
         numbers appear in the output in the same order they
         appeared in the input. Mergesort has worst case O(N log
         N) behaviour, the best value attainable.  And, ironi-
         cally, this mergesort does particularly well where
         quicksort goes quadratic:  mergesort sorts (1..$N,
         1..$N) in O(N) time.  But quicksort was rescued at the
         last moment because it is faster than mergesort on cer-
         tain inputs and platforms. For example, if you really
         don't care about the order of even and odd digits,
         quicksort will run in O(N) time; it's very good at sort-
         ing many repetitions of a small number of distinct ele-
         ments. The quicksort divide and conquer strategy works
         well on platforms with relatively small, very fast,
         caches.  Eventually, the problem gets whittled down to
         one that fits in the cache, from which point it benefits
         from the increased memory speed.

         Quicksort was rescued by implementing a sort pragma to
         control aspects of the sort.  The stable subpragma
         forces stable behaviour, regardless of algorithm.  The
         _quicksort and _mergesort subpragmas are heavy-handed

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         ways to select the underlying implementation. The lead-
         ing "_" is a reminder that these subpragmas may not sur-
         vive beyond 5.8.  More appropriate mechanisms for
         selecting the implementation exist, but they wouldn't
         have arrived in time to save quicksort.

     +   Hashes now use Bob Jenkins "One-at-a-Time" hashing key
         algorithm ( http://burtleburtle.net/bob/hash/doobs.html
         ).  This algorithm is reasonably fast while producing a
         much better spread of values than the old hashing algo-
         rithm (originally by Chris Torek, later tweaked by Ilya
         Zakharevich).  Hash values output from the algorithm on
         a hash of all 3-char printable ASCII keys comes much
         closer to passing the DIEHARD random number generation
         tests.  According to perlbench, this change has not
         affected the overall speed of Perl.

     +   unshift() should now be noticeably faster.

Installation and Configuration Improvements

     Generic Improvements

     +   INSTALL now explains how you can configure Perl to use
         64-bit integers even on non-64-bit platforms.

     +   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.  (Pre-
         viously only $prefix changed.)  If you do not like this
         new behaviour, specify prefix, siteprefix, and ven-
         dorprefix explicitly.

     +   A new optional location for Perl libraries, otherlib-
         dirs, is available. It can be used for example for ven-
         dor add-ons without disturbing Perl's own library direc-
         tories.

     +   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.

     +   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.

     +   Since Perl 5.8 is not binary-compatible with previous

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         releases of Perl, Configure no longer suggests including
         the 5.005 modules in @INC.

     +   Configure "-S" can now run non-interactively. [561]

     +   Configure support for pdp11-style memory models has been
         removed due to obsolescence. [561]

     +   configure.gnu now works with options with whitespace in
         them.

     +   installperl now outputs everything to STDERR.

     +   Because PerlIO is now the default on most platforms,
         "-perlio" doesn't get appended to the $Config{archname}
         (also known as $^O) anymore. Instead, if you explicitly
         choose not to use perlio (Configure command line option
         -Uuseperlio), you will get "-stdio" appended.

     +   Another change related to the architecture name is that
         "-64all" (-Duse64bitall, or "maximally 64-bit") is
         appended only if your pointers are 64 bits wide.  (To be
         exact, the use64bitall is ignored.)

     +   In AFS installations, one can configure the root of the
         AFS to be somewhere else than the default /afs by using
         the Configure parameter "-Dafsroot=/some/where/else".

     +   APPLLIB_EXP, a lesser-known configuration-time defini-
         tion, has been documented.  It can be used to prepend
         site-specific directories to Perl's default search path
         (@INC); see INSTALL for information.

     +   The version of Berkeley DB used when the Perl (and,
         presumably, the DB_File extension) was built is now
         available as @Config{qw(db_version_major
         db_version_minor db_version_patch)} from Perl and as
         "DB_VERSION_MAJOR_CFG DB_VERSION_MINOR_CFG
         DB_VERSION_PATCH_CFG" from C.

     +   Building Berkeley DB3 for compatibility modes for DB,
         NDBM, and ODBM has been documented in INSTALL.

     +   If you have CPAN access (either network or a local copy
         such as a CD-ROM) you can during specify extra modules
         to Configure to build and install with Perl using the
         -Dextras=...  option.  See INSTALL for more details.

     +   In addition to config.over, a new override file,
         config.arch, is available.  This file is supposed to be
         used by hints file writers for architecture-wide changes
         (as opposed to config.over which is for site-wide

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         changes).

     +   If your file system supports symbolic links, you can
         build Perl outside of the source directory by

                 mkdir perl/build/directory
                 cd perl/build/directory
                 sh /path/to/perl/source/Configure -Dmksymlinks ...

         This will create in perl/build/directory a tree of sym-
         bolic links pointing to files in /path/to/perl/source.
         The original files are left unaffected.  After Configure
         has finished, you can just say

                 make all test

         and Perl will be built and tested, all in
         perl/build/directory. [561]

     +   For Perl developers, several new make targets for pro-
         filing and debugging have been added; see perlhack.

         +       Use of the gprof tool to profile Perl has been
                 documented in perlhack.  There is a make target
                 called "perl.gprof" for generating a gprofiled
                 Perl executable.

         +       If you have GCC 3, there is a make target called
                 "perl.gcov" for creating a gcoved Perl execut-
                 able for coverage analysis.  See perlhack.

         +       If you are on IRIX or Tru64 platforms, new
                 profiling/debugging options have been added; see
                 perlhack for more information about pixie and
                 Third Degree.

     +   Guidelines of how to construct minimal Perl installa-
         tions have been added to INSTALL.

     +   The Thread extension is now not built at all under
         ithreads ("Configure -Duseithreads") because it wouldn't
         work anyway (the Thread extension requires being Config-
         ured with "-Duse5005threads").

         Note that the 5.005 threads are unsupported and depre-
         cated: if you have code written for the old threads you
         should migrate it to the new ithreads model.

     +   The Gconvert macro ($Config{d_Gconvert}) used by perl
         for stringifying floating-point numbers is now more
         picky about using sprintf %.*g rules for the conversion.
         Some platforms that used to use gcvt may now resort to

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         the slower sprintf.

     +   The obsolete method of making a special (e.g., debug-
         ging) flavor of perl by saying

                 make LIBPERL=libperld.a

         has been removed. Use -DDEBUGGING instead.

     New Or Improved Platforms

     For the list of platforms known to support Perl, see "Sup-
     ported Platforms" in perlport.

     +   AIX dynamic loading should be now better supported.

     +   AIX should now work better with gcc, threads, and
         64-bitness.  Also the long doubles support in AIX should
         be better now.  See perlaix.

     +   AtheOS ( http://www.atheos.cx/ ) is a new platform.

     +   BeOS has been reclaimed.

     +   The DG/UX platform now supports 5.005-style threads. See
         perldgux.

     +   The DYNIX/ptx platform (also known as dynixptx) is sup-
         ported at or near osvers 4.5.2.

     +   EBCDIC platforms (z/OS (also known as OS/390), POSIX-BC,
         and VM/ESA) have been regained.  Many test suite tests
         still fail and the co-existence of Unicode and EBCDIC
         isn't quite settled, but the situation is much better
         than with Perl 5.6.  See perlos390, perlbs2000 (for
         POSIX-BC), and perlvmesa for more information.

     +   Building perl with -Duseithreads or -Duse5005threads now
         works under HP-UX 10.20 (previously it only worked under
         10.30 or later). You will need a thread library package
         installed. See README.hpux. [561]

     +   Mac OS Classic is now supported in the mainstream source
         package (MacPerl has of course been available since perl
         5.004 but now the source code bases of standard Perl and
         MacPerl have been synchronised) [561]

     +   Mac OS X (or Darwin) should now be able to build Perl
         even on HFS+ filesystems.  (The case-insensitivity used
         to confuse the Perl build process.)

     +   NCR MP-RAS is now supported. [561]

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     +   All the NetBSD specific patches (except for the instal-
         lation specific ones) have been merged back to the main
         distribution.

     +   NetWare from Novell is now supported.  See perlnetware.

     +   NonStop-UX is now supported. [561]

     +   NEC SUPER-UX is now supported.

     +   All the OpenBSD specific patches (except for the instal-
         lation specific ones) have been merged back to the main
         distribution.

     +   Perl has been tested with the GNU pth userlevel thread
         package ( http://www.gnu.org/software/pth/pth.html ).
         All thread tests of Perl now work, but not without
         adding some yield()s to the tests, so while pth (and
         other userlevel thread implementations) can be con-
         sidered to be "working" with Perl ithreads, keep in mind
         the possible non-preemptability of the underlying thread
         implementation.

     +   Stratus VOS is now supported using Perl's native build
         method (Configure).  This is the recommended method to
         build Perl on VOS.  The older methods, which build mini-
         perl, are still available.  See perlvos. [561+]

     +   The Amdahl UTS UNIX mainframe platform is now supported.
         [561]

     +   WinCE is now supported.  See perlce.

     +   z/OS (formerly known as OS/390, formerly known as MVS
         OE) now has support for dynamic loading.  This is not
         selected by default, however, you must specify -Dusedl
         in the arguments of Configure. [561]

Selected Bug Fixes

     Numerous memory leaks and uninitialized memory accesses have
     been hunted down.  Most importantly, anonymous subs used to
     leak quite a bit. [561]

     +   The autouse pragma didn't work for
         Multi::Part::Function::Names.

     +   caller() could cause core dumps in certain situations.
         Carp was sometimes affected by this problem.  In partic-
         ular, caller() now returns a subroutine name of "(unk-
         nown)" for subroutines that have been removed from the
         symbol table.

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     +   chop(@list) in list context returned the characters
         chopped in reverse order.  This has been reversed to be
         in the right order. [561]

     +   Configure no longer includes the DBM libraries (dbm,
         gdbm, db, ndbm) when building the Perl binary.  The only
         exception to this is SunOS 4.x, which needs them. [561]

     +   The behaviour of non-decimal but numeric string con-
         stants such as "0x23" was platform-dependent: in some
         platforms that was seen as 35, in some as 0, in some as
         a floating point number (don't ask).  This was caused by
         Perl's using the operating system libraries in a situa-
         tion where the result of the string to number conversion
         is undefined: now Perl consistently handles such strings
         as zero in numeric contexts.

     +   Several debugger fixes: exit code now reflects the
         script exit code, condition "0" now treated correctly,
         the "d" command now checks line number, $. no longer
         gets corrupted, and all debugger output now goes
         correctly to the socket if RemotePort is set. [561]

     +   The debugger (perl5db.pl) has been modified to present a
         more consistent commands interface, via (Com-
         mandSet=580).  perl5db.t was also added to test the
         changes, and as a placeholder for further tests.

         See perldebug.

     +   The debugger has a new "dumpDepth" option to control the
         maximum depth to which nested structures are dumped.
         The "x" command has been extended so that "x N EXPR"
         dumps out the value of EXPR to a depth of at most N lev-
         els.

     +   The debugger can now show lexical variables if you have
         the CPAN module PadWalker installed.

     +   The order of DESTROYs has been made more predictable.

     +   Perl 5.6.0 could emit spurious warnings about redefini-
         tion of dl_error() when statically building extensions
         into perl. This has been corrected. [561]

     +   dprofpp -R didn't work.

     +   *foo{FORMAT} now works.

     +   Infinity is now recognized as a number.

     +   UNIVERSAL::isa no longer caches methods incorrectly.

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         (This broke the Tk extension with 5.6.0.) [561]

     +   Lexicals I: lexicals outside an eval "" weren't resolved
         correctly inside a subroutine definition inside the eval
         "" if they were not already referenced in the top level
         of the eval""ed code.

     +   Lexicals II: lexicals leaked at file scope into subrou-
         tines that were declared before the lexicals.

     +   Lexical warnings now propagating correctly between
         scopes and into "eval "..."".

     +   "use warnings qw(FATAL all)" did not work as intended.
         This has been corrected. [561]

     +   warnings::enabled() now reports the state of $^W
         correctly if the caller isn't using lexical warnings.
         [561]

     +   Line renumbering with eval and "#line" now works. [561]

     +   Fixed numerous memory leaks, especially in eval "".

     +   Localised tied variables no longer leak memory

             use Tie::Hash;
             tie my %tied_hash => 'Tie::StdHash';

             ...

             # Used to leak memory every time local() was called;
             # in a loop, this added up.
             local($tied_hash{Foo}) = 1;

     +   Localised hash elements (and %ENV) are correctly unlo-
         calised to not exist, if they didn't before they were
         localised.

             use Tie::Hash;
             tie my %tied_hash => 'Tie::StdHash';

             ...

             # Nothing has set the FOO element so far

             { local $tied_hash{FOO} = 'Bar' }

             # This used to print, but not now.
             print "exists!\n" if exists $tied_hash{FOO};

         As a side effect of this fix, tied hash interfaces must

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         define the EXISTS and DELETE methods.

     +   mkdir() now ignores trailing slashes in the directory
         name, as mandated by POSIX.

     +   Some versions of glibc have a broken modfl().  This
         affects builds with "-Duselongdouble".  This version of
         Perl detects this brokenness and has a workaround for
         it.  The glibc release 2.2.2 is known to have fixed the
         modfl() bug.

     +   Modulus of unsigned numbers now works (4063328477 %
         65535 used to return 27406, instead of 27047). [561]

     +   Some "not a number" warnings introduced in 5.6.0 elim-
         inated to be more compatible with 5.005.  Infinity is
         now recognised as a number. [561]

     +   Numeric conversions did not recognize changes in the
         string value properly in certain circumstances. [561]

     +   Attributes (such as :shared) didn't work with our().

     +   our() variables will not cause bogus "Variable will not
         stay shared" warnings. [561]

     +   "our" variables of the same name declared in two sibling
         blocks resulted in bogus warnings about "redeclaration"
         of the variables. The problem has been corrected. [561]

     +   pack "Z" now correctly terminates the string with "\0".

     +   Fix password routines which in some shadow password
         platforms (e.g. HP-UX) caused getpwent() to return every
         other entry.

     +   The PERL5OPT environment variable (for passing command
         line arguments to Perl) didn't work for more than a sin-
         gle group of options. [561]

     +   PERL5OPT with embedded spaces didn't work.

     +   printf() no longer resets the numeric locale to "C".

     +   "qw(a\\b)" now parses correctly as 'a\\b': that is, as
         three characters, not four. [561]

     +   pos() did not return the correct value within s///ge in
         earlier versions.  This is now handled correctly. [561]

     +   Printing quads (64-bit integers) with printf/sprintf now
         works without the q L ll prefixes (assuming you are on a

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         quad-capable platform).

     +   Regular expressions on references and overloaded scalars
         now work. [561+]

     +   Right-hand side magic (GMAGIC) could in many cases such
         as string concatenation be invoked too many times.

     +   scalar() now forces scalar context even when used in
         void context.

     +   SOCKS support is now much more robust.

     +   sort() arguments are now compiled in the right wantarray
         context (they were accidentally using the context of the
         sort() itself). The comparison block is now run in
         scalar context, and the arguments to be sorted are
         always provided list context. [561]

     +   Changed the POSIX character class "[[:space:]]" to
         include the (very rarely used) vertical tab character.
         Added a new POSIX-ish character class "[[:blank:]]"
         which stands for horizontal whitespace (currently, the
         space and the tab).

     +   The tainting behaviour of sprintf() has been rational-
         ized.  It does not taint the result of floating point
         formats anymore, making the behaviour consistent with
         that of string interpolation. [561]

     +   Some cases of inconsistent taint propagation (such as
         within hash values) have been fixed.

     +   The RE engine found in Perl 5.6.0 accidentally pessim-
         ised certain kinds of simple pattern matches.  These are
         now handled better. [561]

     +   Regular expression debug output (whether through "use re
         'debug'" or via "-Dr") now looks better. [561]

     +   Multi-line matches like ""a\nxb\n" =~ /(?!\A)x/m" were
         flawed.  The bug has been fixed. [561]

     +   Use of $& could trigger a core dump under some situa-
         tions.  This is now avoided. [561]

     +   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.
         [561]

     +   readline() on files opened in "slurp" mode could return

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         an extra "" (blank line) at the end in certain situa-
         tions.  This has been corrected. [561]

     +   Autovivification of symbolic references of special vari-
         ables described in perlvar (as in "${$num}") was
         accidentally disabled.  This works again now. [561]

     +   Sys::Syslog ignored the "LOG_AUTH" constant.

     +   $AUTOLOAD, sort(), lock(), and spawning subprocesses in
         multiple threads simultaneously are now thread-safe.

     +   Tie::Array's SPLICE method was broken.

     +   Allow a read-only string on the left-hand side of a
         non-modifying tr///.

     +   If "STDERR" is tied, warnings caused by "warn" and "die"
         now correctly pass to it.

     +   Several Unicode fixes.

         +       BOMs (byte order marks) at the beginning of Perl
                 files (scripts, modules) should now be tran-
                 sparently skipped. UTF-16 and UCS-2 encoded Perl
                 files should now be read correctly.

         +       The character tables have been updated to
                 Unicode 3.2.0.

         +       Comparing with utf8 data does not magically
                 upgrade non-utf8 data into utf8.  (This was a
                 problem for example if you were mixing data from
                 I/O and Unicode data: your output might have got
                 magically encoded as UTF-8.)

         +       Generating illegal Unicode code points such as
                 U+FFFE, or the UTF-16 surrogates, now also gen-
                 erates an optional warning.

         +       "IsAlnum", "IsAlpha", and "IsWord" now match
                 titlecase.

         +       Concatenation with the "." operator or via vari-
                 able interpolation, "eq", "substr", "reverse",
                 "quotemeta", the "x" operator, substitution with
                 "s///", single-quoted UTF-8, should now work.

         +       The "tr///" operator now works.  Note that the
                 "tr///CU" functionality has been removed (but
                 see pack('U0', ...)).

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         +       "eval "v200"" now works.

         +       Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading
                 to spurious warnings. This has been corrected.
                 [561]

         +       Zero entries were missing from the Unicode
                 classes such as "IsDigit".

     +   Large unsigned numbers (those above 2**31) could some-
         times lose their unsignedness, causing bogus results in
         arithmetic operations. [561]

     +   The Perl parser has been stress tested using both random
         input and Markov chain input and the few found crashes
         and lockups have been fixed.

     Platform Specific Changes and Fixes

     +   BSDI 4.*

         Perl now works on post-4.0 BSD/OSes.

     +   All BSDs

         Setting $0 now works (as much as possible; see perlvar
         for details).

     +   Cygwin

         Numerous updates; currently synchronised with Cygwin
         1.3.10.

     +   Previously DYNIX/ptx had problems in its Configure probe
         for non-blocking I/O.

     +   EPOC

         EPOC now better supported.  See README.epoc. [561]

     +   FreeBSD 3.*

         Perl now works on post-3.0 FreeBSDs.

     +   HP-UX

         README.hpux updated; "Configure -Duse64bitall" now
         works; now uses HP-UX malloc instead of Perl malloc.

     +   IRIX

         Numerous compilation flag and hint enhancements;

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         accidental mixing of 32-bit and 64-bit libraries (a
         doomed attempt) made much harder.

     +   Linux

         +       Long doubles should now work (see INSTALL).
                 [561]

         +       Linux previously had problems related to sockad-
                 drlen when using accept(), recvfrom() (in Perl:
                 recv()), getpeername(), and getsockname().

     +   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.

     +   MPE/iX

         MPE/iX update after Perl 5.6.0.  See README.mpeix. [561]

     +   NetBSD/threads: try installing the GNU pth (should be in
         the packages collection, or
         http://www.gnu.org/software/pth/), and Configure with
         -Duseithreads.

     +   NetBSD/sparc

         Perl now works on NetBSD/sparc.

     +   OS/2

         Now works with usethreads (see INSTALL). [561]

     +   Solaris

         64-bitness using the Sun Workshop compiler now works.

     +   Stratus VOS

         The native build method requires at least VOS Release
         14.5.0 and GNU C++/GNU Tools 2.0.1 or later.  The Perl
         pack function now maps overflowed values to +infinity
         and underflowed values to -infinity.

     +   Tru64 (aka Digital UNIX, aka DEC OSF/1)

         The operating system version letter now recorded in
         $Config{osvers}. Allow compiling with gcc (previously

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         explicitly forbidden).  Compiling with gcc still not
         recommended because buggy code results, even with gcc
         2.95.2.

     +   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.

     +   VMS

         See "Socket Extension Dynamic in VMS" and "IEEE-format
         Floating Point Default on OpenVMS Alpha" for important
         changes not otherwise listed here.

         chdir() now works better despite a CRT bug; now works
         with MULTIPLICITY (see INSTALL); now works with Perl's
         malloc.

         The tainting of %ENV elements via "keys" or "values" was
         previously unimplemented.  It now works as documented.

         The "waitpid" emulation has been improved.  The worst
         bug (now fixed) was that a pid of -1 would cause a wild-
         card search of all processes on the system.

         POSIX-style signals are now emulated much better on VMS
         versions prior to 7.0.

         The "system" function and backticks operator have
         improved functionality and better error handling. [561]

         File access tests now use current process privileges
         rather than the user's default privileges, which could
         sometimes result in a mismatch between reported access
         and actual access.  This improvement is only available
         on VMS v6.0 and later.

         There is a new "kill" implementation based on
         "sys$sigprc" that allows older VMS systems (pre-7.0) to
         use "kill" to send signals rather than simply force
         exit.  This implementation also allows later systems to
         call "kill" from within a signal handler.

         Iterative logical name translations are now limited to
         10 iterations in imitation of SHOW LOGICAL and other
         OpenVMS facilities.

     +   Windows

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         +       Signal handling now works better than it used
                 to.  It is now implemented using a Windows mes-
                 sage loop, and is therefore less prone to random
                 crashes.

         +       fork() emulation is now more robust, but still
                 continues to have a few esoteric bugs and
                 caveats.  See perlfork for details. [561+]

         +       A failed (pseudo)fork now returns undef and sets
                 errno to EAGAIN. [561]

         +       The following modules now work on Windows:

                     ExtUtils::Embed         [561]
                     IO::Pipe
                     IO::Poll
                     Net::Ping

         +       IO::File::new_tmpfile() is no longer limited to
                 32767 invocations per-process.

         +       Better chdir() return value for a non-existent
                 directory.

         +       Compiling perl using the 64-bit Platform SDK
                 tools is now supported.

         +       The Win32::SetChildShowWindow() builtin can be
                 used to control the visibility of windows
                 created by child processes.  See Win32 for
                 details.

         +       Non-blocking waits for child processes (or
                 pseudo-processes) are supported via
                 "waitpid($pid, &POSIX::WNOHANG)".

         +       The behavior of system() with multiple arguments
                 has been rationalized. Each unquoted argument
                 will be automatically quoted to protect whi-
                 tespace, and any existing whitespace in the
                 arguments will be preserved.  This improves the
                 portability of system(@args) by avoiding the
                 need for Windows "cmd" shell specific quoting in
                 perl programs.

                 Note that this means that some scripts that may
                 have relied on earlier buggy behavior may no
                 longer work correctly.  For example,
                 "system("nmake /nologo", @args)" will now
                 attempt to run the file "nmake /nologo" and will
                 fail when such a file isn't found. On the other

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                 hand, perl will now execute code such as
                 "system("c:/Program Files/MyApp/foo.exe",
                 @args)" correctly.

         +       The perl header files no longer suppress common
                 warnings from the Microsoft Visual C++ compiler.
                 This means that additional warnings may now show
                 up when compiling XS code.

         +       Borland C++ v5.5 is now a supported compiler
                 that can build Perl. However, the generated
                 binaries continue to be incompatible with those
                 generated by the other supported compilers (GCC
                 and Visual C++). [561]

         +       Duping socket handles with open(F, ">&MYSOCK")
                 now works under Windows 9x. [561]

         +       Current directory entries in %ENV are now
                 correctly propagated to child processes. [561]

         +       New %ENV entries now propagate to subprocesses.
                 [561]

         +       Win32::GetCwd() correctly returns C:\ instead of
                 C: when at the drive root. Other bugs in chdir()
                 and Cwd::cwd() have also been fixed. [561]

         +       The makefiles now default to the features
                 enabled in ActiveState ActivePerl (a popular
                 Win32 binary distribution). [561]

         +       HTML files will now be installed in c:\perl\html
                 instead of c:\perl\lib\pod\html

         +       REG_EXPAND_SZ keys are now allowed in registry
                 settings used by perl. [561]

         +       Can now send() from all threads, not just the
                 first one. [561]

         +       ExtUtils::MakeMaker now uses $ENV{LIB} to search
                 for libraries. [561]

         +       Less stack reserved per thread so that more
                 threads can run concurrently. (Still 16M per
                 thread.) [561]

         +       "File::Spec->tmpdir()" now prefers C:/temp over
                 /tmp (works better when perl is running as ser-
                 vice).

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         +       Better UNC path handling under ithreads. [561]

         +       wait(), waitpid(), and backticks now return the
                 correct exit status under Windows 9x. [561]

         +       A socket handle leak in accept() has been fixed.
                 [561]

New or Changed Diagnostics

     Please see perldiag for more details.

     +   Ambiguous range in the transliteration operator (like
         a-z-9) now gives a warning.

     +   chdir("") and chdir(undef) now give a deprecation warn-
         ing because they cause a possible unintentional chdir to
         the home directory. Say chdir() if you really mean that.

     +   Two new debugging options have been added: if you have
         compiled your Perl with debugging, you can use the -DT
         [561] and -DR options to trace tokenising and to add
         reference counts to displaying variables, respectively.

     +   The lexical warnings category "deprecated" is no longer
         a sub-category of the "syntax" category. It is now a
         top-level category in its own right.

     +   Unadorned dump() will now give a warning suggesting to
         use explicit CORE::dump() if that's what really is
         meant.

     +   The "Unrecognized escape" warning has been extended to
         include "\8", "\9", and "\_".  There is no need to
         escape any of the "\w" characters.

     +   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 by a
         "<-- HERE" marker.

     +   Various I/O (and socket) functions like binmode(),
         close(), and so forth now more consistently warn if they
         are used illogically either on a yet unopened or on an
         already closed filehandle (or socket).

     +   Using lstat() on a filehandle now gives a warning.
         (It's a non-sensical thing to do.)

     +   The "-M" and "-m" options now warn if you didn't supply
         the module name.

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     +   If you in "use" specify a required minimum version,
         modules matching the name and but not defining a $VER-
         SION will cause a fatal failure.

     +   Using negative offset for vec() in lvalue context is now
         a warnable offense.

     +   Odd number of arguments to overload::constant now eli-
         cits a warning.

     +   Odd number of elements in anonymous hash now elicits a
         warning.

     +   The various "opened only for", "on closed", "never
         opened" warnings drop the "main::" prefix for filehan-
         dles in the "main" package, for example "STDIN" instead
         of "main::STDIN".

     +   Subroutine prototypes are now checked more carefully,
         you may get warnings for example if you have used non-
         prototype characters.

     +   If an attempt to use a (non-blessed) reference as an
         array index is made, a warning is given.

     +   "push @a;" and "unshift @a;" (with no values to push or
         unshift) now give a warning.  This may be a problem for
         generated and evaled code.

     +   If you try to "pack" in perlfunc a number less than 0 or
         larger than 255 using the "C" format you will get an
         optional warning.  Similarly for the "c" format and a
         number less than -128 or more than 127.

     +   pack "P" format now demands an explicit size.

     +   unpack "w" now warns of unterminated compressed
         integers.

     +   Warnings relating to the use of PerlIO have been added.

     +   Certain regex modifiers such as "(?o)" make sense only
         if applied to the entire regex.  You will get an
         optional warning if you try to do otherwise.

     +   Variable length lookbehind has not yet been implemented,
         trying to use it will tell that.

     +   Using arrays or hashes as references (e.g. "%foo->{bar}"
         has been deprecated for a while.  Now you will get an
         optional warning.

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     +   Warnings relating to the use of the new restricted
         hashes feature have been added.

     +   Self-ties of arrays and hashes are not supported and
         fatal errors will happen even at an attempt to do so.

     +   Using "sort" in scalar context now issues an optional
         warning. This didn't do anything useful, as the sort was
         not performed.

     +   Using the /g modifier in split() is meaningless and will
         cause a warning.

     +   Using splice() past the end of an array now causes a
         warning.

     +   Malformed Unicode encodings (UTF-8 and UTF-16) cause a
         lot of warnings, as does trying to use UTF-16 surrogates
         (which are unimplemented).

     +   Trying to use Unicode characters on an I/O stream
         without marking the stream's encoding (using open() or
         binmode()) will cause "Wide character" warnings.

     +   Use of v-strings in use/require causes a (backward) por-
         tability warning.

     +   Warnings relating to the use interpreter threads and
         their shared data have been added.

Changed Internals

     +   PerlIO is now the default.

     +   perlapi.pod (a companion to perlguts) now attempts to
         document the internal API.

     +   You can now build a really minimal perl called micro-
         perl. Building microperl does not require even running
         Configure; "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 hack-
         ers only.

     +   Added rsignal(), whichsig(), do_join(), op_clear,
         op_null, ptr_table_clear(), ptr_table_free(),
         sv_setref_uv(), and several UTF-8 interfaces to the pub-
         licised API.  For the full list of the available APIs
         see perlapi.

     +   Made possible to propagate customised exceptions via
         croak()ing.

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     +   Now xsubs can have attributes just like subs.  (Well, at
         least the built-in attributes.)

     +   dTHR and djSP have been obsoleted; the former removed
         (because it's a no-op) and the latter replaced with dSP.

     +   PERL_OBJECT has been completely removed.

     +   The MAGIC constants (e.g. 'P') have been macrofied (e.g.
         "PERL_MAGIC_TIED") for better source code readability
         and maintainability.

     +   The regex compiler now maintains a structure that iden-
         tifies nodes in the compiled bytecode with the
         corresponding syntactic features of the original regex
         expression.  The information is attached to the new
         "offsets" member of the "struct regexp". See perldebguts
         for more complete information.

     +   The C code has been made much more "gcc -Wall" clean.
         Some warning messages still remain in some platforms, so
         if you are compiling with gcc you may see some warnings
         about dubious practices.  The warnings are being worked
         on.

     +   perly.c, sv.c, and sv.h have now been extensively com-
         mented.

     +   Documentation on how to use the Perl source repository
         has been added to Porting/repository.pod.

     +   There are now several profiling make targets.

Security Vulnerability Closed [561]

     (This change was already made in 5.7.0 but bears repeating
     here.) (5.7.0 came out before 5.6.1: the development branch
     5.7 released earlier than the maintenance branch 5.6)

     A potential security vulnerability in the optional suidperl
     component of Perl was identified in August 2000.  suidperl
     is neither built nor installed by default.  As of November
     2001 the only known vulnerable platform is Linux, most
     likely all Linux distributions.  CERT and various vendors
     and distributors have been alerted about the vulnerability.
     See
     http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
     for more information.

     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

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     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 suid-
     perl is not installed, you are safe.

     The exploit attempt reporting feature has been completely
     removed from Perl 5.8.0 (and the maintenance release 5.6.1,
     and it was removed also from all the Perl 5.7 releases), so
     that particular vulnerability isn't there anymore.  However,
     further security vulnerabilities are, unfortunately, always
     possible.  The suidperl functionality is most probably going
     to be removed in Perl 5.10.  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/ ).

New Tests

     Several new tests have been added, especially for the lib
     and ext subsections.  There are now about 69 000 individual
     tests (spread over about 700 test scripts), in the regres-
     sion suite (5.6.1 has about 11 700 tests, in 258 test
     scripts)  The exact numbers depend on the platform and Perl
     configuration used.  Many of the new tests are of course
     introduced by the new modules, but still in general Perl is
     now more thoroughly tested.

     Because of the large number of tests, running the regression
     suite will take considerably longer time than it used to:
     expect the suite to take up to 4-5 times longer to run than
     in perl 5.6.  On a really fast machine you can hope to fin-
     ish the suite in about 6-8 minutes (wallclock time).

     The tests are now reported in a different order than in ear-
     lier Perls. (This happens because the test scripts from
     under t/lib have been moved to be closer to the
     library/extension they are testing.)

Known Problems

     The Compiler Suite Is Still Very Experimental

     The compiler suite is slowly getting better but it continues
     to be highly experimental.  Use in production environments
     is discouraged.

     Localising Tied Arrays and Hashes Is Broken

         local %tied_array;

     doesn't work as one would expect: the old value is restored
     incorrectly.  This will be changed in a future release, but
     we don't know yet what the new semantics will exactly be.

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     In any case, the change will break existing code that relies
     on the current (ill-defined) semantics, so just avoid doing
     this in general.

     Building Extensions Can Fail Because Of Largefiles

     Some extensions like mod_perl 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 they may 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 to) link together at all
     binaries with different ideas about file offsets; all this
     is platform-dependent.

     Modifying $_ Inside for(..)

        for (1..5) { $_++ }

     works without complaint.  It shouldn't.  (You should be able
     to modify only lvalue elements inside the loops.)  You can
     see the correct behaviour by replacing the 1..5 with 1, 2,
     3, 4, 5.

     mod_perl 1.26 Doesn't Build With Threaded Perl

     Use mod_perl 1.27 or higher.

     lib/ftmp-security tests warn 'system possibly insecure'

     Don't panic.  Read the 'make test' section of INSTALL
     instead.

     libwww-perl (LWP) fails base/date #51

     Use libwww-perl 5.65 or later.

     PDL failing some tests

     Use PDL 2.3.4 or later.

     Perl_get_sv

     You may get errors like 'Undefined symbol "Perl_get_sv"' or
     "can't resolve symbol 'Perl_get_sv'", or the symbol may be

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     "Perl_sv_2pv". This probably means that you are trying to
     use an older shared Perl library (or extensions linked with
     such) with Perl 5.8.0 executable. Perl used to have such a
     subroutine, but that is no more the case. Check your shared
     library path, and any shared Perl libraries in those direc-
     tories.

     Sometimes this problem may also indicate a partial Perl
     5.8.0 installation, see "Mac OS X dyld undefined symbols"
     for an example and how to deal with it.

     Self-tying Problems

     Self-tying of arrays and hashes is broken in rather deep and
     hard-to-fix ways.  As a stop-gap measure to avoid people
     from getting frustrated at the mysterious results (core
     dumps, most often), it is forbidden for now (you will get a
     fatal error even from an attempt).

     A change to self-tying of globs has caused them to be recur-
     sively referenced (see: "Two-Phased Garbage Collection" in
     perlobj).  You will now need an explicit untie to destroy a
     self-tied glob.  This behaviour may be fixed at a later
     date.

     Self-tying of scalars and IO thingies works.

     ext/threads/t/libc

     If this test fails, it indicates that your libc (C library)
     is not threadsafe.  This particular test stress tests the
     localtime() call to find out whether it is threadsafe.  See
     perlthrtut for more information.

     Failure of Thread (5.005-style) tests

     Note that support for 5.005-style threading is deprecated,
     experimental and practically unsupported.  In 5.10, it is
     expected to be removed.  You should migrate your code to
     ithreads.

     The following tests are known to fail due to fundamental
     problems in the 5.005 threading implementation. These are
     not new failures--Perl 5.005_0x has the same bugs, but
     didn't have these tests.

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      ../ext/B/t/xref.t                    255 65280    14   12  85.71%  3-14
      ../ext/List/Util/t/first.t           255 65280     7    4  57.14%  2 5-7
      ../lib/English.t                       2   512    54    2   3.70%  2-3
      ../lib/FileCache.t                                 5    1  20.00%  5
      ../lib/Filter/Simple/t/data.t                      6    3  50.00%  1-3
      ../lib/Filter/Simple/t/filter_only.                9    3  33.33%  1-2 5
      ../lib/Math/BigInt/t/bare_mbf.t                 1627    4   0.25%  8 11 1626-1627
      ../lib/Math/BigInt/t/bigfltpm.t                 1629    4   0.25%  10 13 1628-
                                                                         1629
      ../lib/Math/BigInt/t/sub_mbf.t                  1633    4   0.24%  8 11 1632-1633
      ../lib/Math/BigInt/t/with_sub.t                 1628    4   0.25%  9 12 1627-1628
      ../lib/Tie/File/t/31_autodefer.t     255 65280    65   32  49.23%  34-65
      ../lib/autouse.t                                  10    1  10.00%  4
      op/flip.t                                         15    1   6.67%  15

     These failures are unlikely to get fixed as 5.005-style
     threads are considered fundamentally broken.  (Basically
     what happens is that competing threads can corrupt shared
     global state, one good example being regular expression
     engine's state.)

     Timing problems

     The following tests may fail intermittently because of tim-
     ing problems, for example if the system is heavily loaded.

         t/op/alarm.t
         ext/Time/HiRes/HiRes.t
         lib/Benchmark.t
         lib/Memoize/t/expmod_t.t
         lib/Memoize/t/speed.t

     In case of failure please try running them manually, for
     example

         ./perl -Ilib ext/Time/HiRes/HiRes.t

     Tied/Magical Array/Hash Elements Do Not Autovivify

     For normal arrays "$foo = \$bar[1]" will assign "undef" to
     $bar[1] (assuming that it didn't exist before), but for
     tied/magical arrays and hashes such autovivification does
     not happen because there is currently no way to catch the
     reference creation. The same problem affects slicing over
     non-existent indices/keys of a tied/magical array/hash.

     Unicode in package/class and subroutine names does not work

     One can have Unicode in identifier names, but not in
     package/class or subroutine names.  While some limited func-
     tionality towards this does exist as of Perl 5.8.0, that is
     more accidental than designed; use of Unicode for the said

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     purposes is unsupported.

     One reason of this unfinishedness is its (currently)
     inherent unportability: since both package names and subrou-
     tine names may need to be mapped to file and directory
     names, the Unicode capability of the filesystem becomes
     important-- and there unfortunately aren't portable answers.

Platform Specific Problems

     AIX

     +   If using the AIX native make command, instead of just
         "make" issue "make all".  In some setups the former has
         been known to spuriously also try to run "make install".
         Alternatively, you may want to use GNU make.

     +   In AIX 4.2, Perl extensions that use C++ functions that
         use statics may have problems in that the statics are
         not getting initialized. In newer AIX releases, this has
         been solved by linking Perl with the libC_r library, but
         unfortunately in AIX 4.2 the said library has an obscure
         bug where the various functions related to time (such as
         time() and gettimeofday()) return broken values, and
         therefore in AIX 4.2 Perl is not linked against libC_r.

     +   vac 5.0.0.0 May Produce Buggy Code For Perl

         The AIX C compiler vac version 5.0.0.0 may produce buggy
         code, resulting in a few random tests failing when run
         as part of "make test", but when the failing tests are
         run by hand, they succeed. We suggest upgrading to at
         least vac version 5.0.1.0, that has been known to com-
         pile Perl correctly.  "lslpp -L|grep vac.C" will tell
         you the vac version.  See README.aix.

     +   If building threaded Perl, you may get compilation warn-
         ing from pp_sys.c:

           "pp_sys.c", line 4651.39: 1506-280 (W) Function argument assignment between types "unsigned char*" and "const void*" is not allowed.

         This is harmless; it is caused by the getnetbyaddr() and
         getnetbyaddr_r() having slightly different types for
         their first argument.

     Alpha systems with old gccs fail several tests

     If you see op/pack, op/pat, op/regexp, or ext/Storable tests
     failing in a Linux/alpha or *BSD/Alpha, it's probably time
     to upgrade your gcc. gccs prior to 2.95.3 are definitely not
     good enough, and gcc 3.1 may be even better.  (RedHat
     Linux/alpha with gcc 3.1 reported no problems, as did Linux
     2.4.18 with gcc 2.95.4.)  (In Tru64, it is preferable to use

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     the bundled C compiler.)

     AmigaOS

     Perl 5.8.0 doesn't build in AmigaOS.  It broke at some point
     during the ithreads work and we could not find Amiga experts
     to unbreak the problems.  Perl 5.6.1 still works for AmigaOS
     (as does the 5.7.2 development release).

     BeOS

     The following tests fail on 5.8.0 Perl in BeOS Personal
     5.03:

      t/op/lfs............................FAILED at test 17
      t/op/magic..........................FAILED at test 24
      ext/Fcntl/t/syslfs..................FAILED at test 17
      ext/File/Glob/t/basic...............FAILED at test 3
      ext/POSIX/t/sigaction...............FAILED at test 13
      ext/POSIX/t/waitpid.................FAILED at test 1

     See perlbeos (README.beos) for more details.

     Cygwin "unable to remap"

     For example when building the Tk extension for Cygwin, you
     may get an error message saying "unable to remap". This is
     known problem with Cygwin, and a workaround is detailed in
     here:
     http://sources.redhat.com/ml/cygwin/2001-12/msg00894.html

     Cygwin ndbm tests fail on FAT

     One can build but not install (or test the build of) the
     NDBM_File on FAT filesystems.  Installation (or build) on
     NTFS works fine. If one attempts the test on a FAT install
     (or build) the following failures are expected:

      ../ext/NDBM_File/ndbm.t       13  3328    71   59  83.10%  1-2 4 16-71
      ../ext/ODBM_File/odbm.t      255 65280    ??   ??       %  ??
      ../lib/AnyDBM_File.t           2   512    12    2  16.67%  1 4
      ../lib/Memoize/t/errors.t      0   139    11    5  45.45%  7-11
      ../lib/Memoize/t/tie_ndbm.t   13  3328     4    4 100.00%  1-4
      run/fresh_perl.t                          97    1   1.03%  91

     NDBM_File fails and ODBM_File just coredumps.

     If you intend to run only on FAT (or if using AnyDBM_File on
     FAT), run Configure with the -Ui_ndbm and -Ui_dbm options to
     prevent NDBM_File and ODBM_File being built.

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     DJGPP Failures

      t/op/stat............................FAILED at test 29
      lib/File/Find/t/find.................FAILED at test 1
      lib/File/Find/t/taint................FAILED at test 1
      lib/h2xs.............................FAILED at test 15
      lib/Pod/t/eol........................FAILED at test 1
      lib/Test/Harness/t/strap-analyze.....FAILED at test 8
      lib/Test/Harness/t/test-harness......FAILED at test 23
      lib/Test/Simple/t/exit...............FAILED at test 1

     The above failures are known as of 5.8.0 with native builds
     with long filenames, but there are a few more if running
     under dosemu because of limitations (and maybe bugs) of
     dosemu:

      t/comp/cpp...........................FAILED at test 3
      t/op/inccode.........................(crash)

     and a few lib/ExtUtils tests, and several hundred
     Encode/t/Aliases.t failures that work fine with long
     filenames.  So you really might prefer native builds and
     long filenames.

     FreeBSD built with ithreads coredumps reading large direc-
     tories

     This is a known bug in FreeBSD 4.5's readdir_r(), it has
     been fixed in FreeBSD 4.6 (see perlfreebsd
     (README.freebsd)).

     FreeBSD Failing locale Test 117 For ISO 8859-15 Locales

     The ISO 8859-15 locales may fail the locale test 117 in
     FreeBSD. This is caused by the characters \xFF (y with
     diaeresis) and \xBE (Y with diaeresis) not behaving
     correctly when being matched case-insensitively.  Apparently
     this problem has been fixed in the latest FreeBSD releases.
     ( http://www.freebsd.org/cgi/query-pr.cgi?pr=34308 )

     IRIX fails ext/List/Util/t/shuffle.t or Digest::MD5

     IRIX with MIPSpro 7.3.1.2m or 7.3.1.3m compiler may fail the
     List::Util test ext/List/Util/t/shuffle.t by dumping core.
     This seems to be a compiler error since if compiled with gcc
     no core dump ensues, and no failures have been seen on the
     said test on any other platform.

     Similarly, building the Digest::MD5 extension has been known
     to fail with "*** Termination code 139 (bu21)".

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     The cure is to drop optimization level (Configure
     -Doptimize=-O2).

     HP-UX lib/posix Subtest 9 Fails When LP64-Configured

     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.

     Linux with glibc 2.2.5 fails t/op/int subtest #6 with
     -Duse64bitint

     This is a known bug in the glibc 2.2.5 with long long
     integers. (
     http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=65612 )

     Linux With Sfio Fails op/misc Test 48

     No known fix.

     Mac OS X

     Please remember to set your environment variable LC_ALL to
     "C" (setenv LC_ALL C) before running "make test" to avoid a
     lot of warnings about the broken locales of Mac OS X.

     The following tests are known to fail in Mac OS X 10.1.5
     because of buggy (old) implementations of Berkeley DB
     included in Mac OS X:

      Failed Test                 Stat Wstat Total Fail  Failed  List of Failed
      -------------------------------------------------------------------------
      ../ext/DB_File/t/db-btree.t    0    11    ??   ??       %  ??
      ../ext/DB_File/t/db-recno.t              149    3   2.01%  61 63 65

     If you are building on a UFS partition, you will also prob-
     ably see t/op/stat.t subtest #9 fail.  This is caused by
     Darwin's UFS not supporting inode change time.

     Also the ext/POSIX/t/posix.t subtest #10 fails but it is
     skipped for now because the failure is Apple's fault, not
     Perl's (blocked signals are lost).

     If you Configure with ithreads, ext/threads/t/libc.t will
     fail. Again, this is not Perl's fault-- the libc of Mac OS X
     is not threadsafe (in this particular test, the localtime()
     call is found to be threadunsafe.)

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     Mac OS X dyld undefined symbols

     If after installing Perl 5.8.0 you are getting warnings
     about missing symbols, for example

         dyld: perl Undefined symbols
         _perl_sv_2pv
         _perl_get_sv

     you probably have an old pre-Perl-5.8.0 installation (or
     parts of one) in /Library/Perl (the undefined symbols used
     to exist in pre-5.8.0 Perls). It seems that for some reason
     "make install" doesn't always completely overwrite the files
     in /Library/Perl.  You can move the old Perl shared library
     out of the way like this:

         cd /Library/Perl/darwin/CORE
         mv libperl.dylib libperlold.dylib

     and then reissue "make install".  Note that the above of
     course is extremely disruptive for anything using the
     /usr/local/bin/perl. If that doesn't help, you may have to
     try removing all the .bundle files from beneath
     /Library/Perl, and again "make install"-ing.

     OS/2 Test Failures

     The following tests are known to fail on OS/2 (for clarity
     only the failures are shown, not the full error messages):

      ../lib/ExtUtils/t/Mkbootstrap.t    1   256    18    1   5.56%  8
      ../lib/ExtUtils/t/Packlist.t       1   256    34    1   2.94%  17
      ../lib/ExtUtils/t/basic.t          1   256    17    1   5.88%  14
      lib/os2_process.t                  2   512   227    2   0.88%  174 209
      lib/os2_process_kid.t                        227    2   0.88%  174 209
      lib/rx_cmprt.t                   255 65280    18    3  16.67%  16-18

     op/sprintf tests 91, 129, and 130

     The op/sprintf tests 91, 129, and 130 are known to fail on
     some platforms. Examples include any platform using sfio,
     and Compaq/Tandem's NonStop-UX.

     Test 91 is known to fail on QNX6 (nto), because "sprintf
     '%e',0" incorrectly produces 0.000000e+0 instead of
     0.000000e+00.

     For tests 129 and 130, the failing platforms do not comply
     with the ANSI C Standard: lines 19ff on page 134 of ANSI
     X3.159 1989, to be exact.  (They produce something other
     than "1" and "-1" when formatting 0.6 and -0.6 using the
     printf format "%.0f"; most often, they produce "0" and

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     "-0".)

     SCO

     The socketpair tests are known to be unhappy in SCO
     3.2v5.0.4:

      ext/Socket/socketpair.t...............FAILED tests 15-45

     Solaris 2.5

     In case you are still using Solaris 2.5 (aka SunOS 5.5), you
     may experience failures (the test core dumping) in
     lib/locale.t. The suggested cure is to upgrade your Solaris.

     Solaris x86 Fails Tests With -Duse64bitint

     The following tests are known to fail in Solaris x86 with
     Perl configured to use 64 bit integers:

      ext/Data/Dumper/t/dumper.............FAILED at test 268
      ext/Devel/Peek/Peek..................FAILED at test 7

     SUPER-UX (NEC SX)

     The following tests are known to fail on SUPER-UX:

      op/64bitint...........................FAILED tests 29-30, 32-33, 35-36
      op/arith..............................FAILED tests 128-130
      op/pack...............................FAILED tests 25-5625
      op/pow................................
      op/taint..............................# msgsnd failed
      ../ext/IO/lib/IO/t/io_poll............FAILED tests 3-4
      ../ext/IPC/SysV/ipcsysv...............FAILED tests 2, 5-6
      ../ext/IPC/SysV/t/msg.................FAILED tests 2, 4-6
      ../ext/Socket/socketpair..............FAILED tests 12
      ../lib/IPC/SysV.......................FAILED tests 2, 5-6
      ../lib/warnings.......................FAILED tests 115-116, 118-119

     The op/pack failure ("Cannot compress negative numbers at
     op/pack.t line 126") is serious but as of yet unsolved.  It
     points at some problems with the signedness handling of the
     C compiler, as do the 64bitint, arith, and pow failures.
     Most of the rest point at problems with SysV IPC.

     Term::ReadKey not working on Win32

     Use Term::ReadKey 2.20 or later.

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     UNICOS/mk

     +   During Configure, the test

             Guessing which symbols your C compiler and preprocessor define...

         will probably fail with error messages like

             CC-20 cc: ERROR File = try.c, Line = 3
               The identifier "bad" is undefined.

               bad switch yylook 79bad switch yylook 79bad switch yylook 79bad switch yylook 79#ifdef A29K
               ^

             CC-65 cc: ERROR File = try.c, Line = 3
               A semicolon is expected at this point.

         This is caused by a bug in the awk utility of UNICOS/mk.
         You can ignore the error, but it does cause a slight
         problem: you cannot fully benefit from the h2ph utility
         (see h2ph) that can be used to convert C headers to Perl
         libraries, mainly used to be able to access from Perl
         the constants defined using C preprocessor, cpp.
         Because of the above error, parts of the converted
         headers will be invisible. Luckily, these days the need
         for h2ph is rare.

     +   If building Perl with interpreter threads (ithreads),
         the getgrent(), getgrnam(), and getgrgid() functions
         cannot return the list of the group members due to a bug
         in the multithreaded support of UNICOS/mk.  What this
         means is that in list context the functions will return
         only three values, not four.

     UTS

     There are a few known test failures, see perluts
     (README.uts).

     VOS (Stratus)

     When Perl is built using the native build process on VOS
     Release 14.5.0 and GNU C++/GNU Tools 2.0.1, all attempted
     tests either pass or result in TODO (ignored) failures.

     VMS

     There should be no reported test failures with a default
     configuration, though there are a number of tests marked
     TODO that point to areas needing further debugging and/or
     porting work.

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     Win32

     In multi-CPU boxes, there are some problems with the I/O
     buffering: some output may appear twice.

     XML::Parser not working

     Use XML::Parser 2.31 or later.

     z/OS (OS/390)

     z/OS has rather many test failures but the situation is
     actually much better than it was in 5.6.0; it's just that so
     many new modules and tests have been added.

      Failed Test                   Stat Wstat Total Fail  Failed  List of Failed
      ---------------------------------------------------------------------------
      ../ext/Data/Dumper/t/dumper.t              357    8   2.24%  311 314 325 327
                                                                   331 333 337 339
      ../ext/IO/lib/IO/t/io_unix.t                 5    4  80.00%  2-5
      ../ext/Storable/t/downgrade.t   12  3072   169   12   7.10%  14-15 46-47 78-79
                                                                   110-111 150 161
      ../lib/ExtUtils/t/Constant.t   121 30976    48   48 100.00%  1-48
      ../lib/ExtUtils/t/Embed.t                    9    9 100.00%  1-9
      op/pat.t                                   922    7   0.76%  665 776 785 832-
                                                                   834 845
      op/sprintf.t                               224    3   1.34%  98 100 136
      op/tr.t                                     97    5   5.15%  63 71-74
      uni/fold.t                                 780    6   0.77%  61 169 196 661
                                                                   710-711

     The failures in dumper.t and downgrade.t are problems in the
     tests, those in io_unix and sprintf are problems in the USS
     (UDP sockets and printf formats).  The pat, tr, and fold
     failures are genuine Perl problems caused by EBCDIC (and in
     the pat and fold cases, combining that with Unicode).  The
     Constant and Embed are probably problems in the tests (since
     they test Perl's ability to build extensions, and that seems
     to be working reasonably well.)

     Unicode Support on EBCDIC Still Spotty

     Though mostly working, Unicode support still has problem
     spots on EBCDIC platforms.  One such known spot are the
     "\p{}" and "\P{}" regular expression constructs for code
     points less than 256: the "pP" are testing for Unicode code
     points, not knowing about EBCDIC.

     Seen In Perl 5.7 But Gone Now

     "Time::Piece" (previously known as "Time::Object") was
     removed because it was felt that it didn't have enough value

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     in it to be a core module.  It is still a useful module,
     though, and is available from the CPAN.

     Perl 5.8 unfortunately does not build anymore on AmigaOS;
     this broke accidentally at some point.  Since there are not
     that many Amiga developers available, we could not get this
     fixed and tested in time for 5.8.0.  Perl 5.6.1 still works
     for AmigaOS (as does the 5.7.2 development release).

     The "PerlIO::Scalar" and "PerlIO::Via" (capitalised) were
     renamed as "PerlIO::scalar" and "PerlIO::via" (all lower-
     case) just before 5.8.0. The main rationale was to have all
     core PerlIO layers to have all lowercase names.  The "plu-
     gins" are named as usual, for example
     "PerlIO::via::QuotedPrint".

     The "threads::shared::queue" and
     "threads::shared::semaphore" were renamed as "Thread::Queue"
     and "Thread::Semaphore" just before 5.8.0. The main
     rationale was to have thread modules to obey normal naming,
     "Thread::" (the "threads" and "threads::shared" themselves
     are more pragma-like, they affect compile-time, so they stay
     lowercase).

Reporting Bugs

     If you find what you think is a bug, you might check the
     articles recently posted to the comp.lang.perl.misc news-
     group and the perl bug database at http://bugs.perl.org/ .
     There may also be information at http://www.perl.com/ , the
     Perl Home Page.

     If you believe you have an unreported bug, please run the
     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 "perl -V", will be sent off
     to perlbug@perl.org to be analysed by the Perl porting team.

SEE ALSO

     The Changes file for exhaustive details on what changed.

     The INSTALL file for how to build Perl.

     The README file for general stuff.

     The Artistic and Copying files for copyright information.

HISTORY

     Written by Jarkko Hietaniemi <jhi@iki.fi>.

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