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perldelta - what is new for perl v5.8.0


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.something).

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

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 architecture 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.

In future releases of Perl, non-PerlIO aware XS modules may become completely unsupported. This shouldn't be too difficult 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 platforms 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 emulated 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 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 remaining 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 character 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 versions, 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 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]


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.

PerlIO is Now The Default


The new interpreter threads ("ithreads" for short) implementation 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 inopportune 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 finished 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 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

Modules and Pragmata

New Modules and Pragmata

Updated And Improved Modules and Pragmata

Utility Changes

New Documentation

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

   perljp perlko perlcn perltw  

Performance Enhancements

Installation and Configuration Improvements

Generic Improvements

New Or Improved Platforms

For the list of platforms known to support Perl, see perlport/"Supported Platforms".

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]

Platform Specific Changes and Fixes

New or Changed Diagnostics

Please see perldiag for more details.

Changed Internals

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 access to a root shell, resulting in a serious compromise instead of reporting the exploit attempt. If you don't have /bin/mail, or if you have 'safe setuid scripts', or if suidperl is not installed, you are safe.

The exploit attempt reporting feature has been completely removed from 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 regression 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 finish the suite in about 6-8 minutes (wallclock time).

The tests are now reported in a different order than in earlier 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. 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.


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

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 recursively referenced (see: perlobj/"Two-Phased Garbage Collection"). 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.


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.

 ../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-
 ../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 timing problems, for example if the system is heavily loaded.


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 functionality towards this does exist as of Perl 5.8.0, that is more accidental than designed; use of Unicode for the said purposes is unsupported.

One reason of this unfinishedness is its (currently) inherent unportability: since both package names and subroutine 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


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 the bundled C compiler.)


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 the 5.7.2 development release).


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.

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

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 directories

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 or 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)".

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 probably 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.)

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

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 "-0".)

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  


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/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.



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.


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.


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

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 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 the 5.7.2 development release).

The PerlIO::Scalar and PerlIO::Via (capitalised) were renamed as PerlIO::scalar and PerlIO::via (all lowercase) just before 5.8.0. The main rationale was to have all core PerlIO layers to have all lowercase names. The "plugins" 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 newsgroup 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.


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.


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

The use of the camel image in association with the Perl language is a trademark of O'Reilly & Associates. Used with permission.