NAME¶
perl572delta - what's new for perl v5.7.2
DESCRIPTION¶
This document describes differences between the 5.7.1 release and the 5.7.2
release.
(To view the differences between the 5.6.0 release and the 5.7.0 release, see
perl570delta. To view the differences between the 5.7.0 release and the 5.7.1
release, see perl571delta.)
Security Vulnerability Closed¶
(This change was already made in 5.7.0 but bears repeating here.)
A security vulnerability affecting all Perl versions prior to 5.6.1 was found in
August 2000. The vulnerability does not affect default installations and as
far as is known affects only the Linux platform.
You should upgrade your Perl to 5.6.1 as soon as possible. Patches for earlier
releases exist but using the patches require full recompilation from the
source code anyway, so 5.6.1 is your best choice.
See
http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt for more
information.
Incompatible Changes¶
If your pointers are 64 bits wide, the Perl malloc is no more being used because
it simply does not work with 8-byte pointers. Also, usually the system malloc
on such platforms are much better optimized for such large memory models than
the Perl malloc.
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 modperl which
are using the AIX native interface.
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.
Different Definition of the Unicode Character Classes
\p{In...}¶
As suggested by the Unicode consortium, the Unicode character classes now prefer
scripts as opposed to
blocks (as defined by Unicode); in Perl,
when the "\p{In....}" and the "\p{In....}" regular
expression constructs are used. This has changed the definition of some of
those character classes.
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 256 characters based on the Unicode numbering.
In general this change results in more inclusive Unicode character classes, but
changes to the other direction also do take place: 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").
Changes in the character class semantics may have happened if a script and a
block happen to have the same name, for example "Hebrew". In such
cases the script wins and "\p{InHebrew}" now means the script
definition of Hebrew. The block definition in still available, though, by
appending "Block" to the name: "\p{InHebrewBlock}" means
what "\p{InHebrew}" meant in perl 5.6.0. For the full list of
affected character classes, see "Blocks" in perlunicode.
Deprecations¶
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 syntaxes "@a->[...]" and "@h->{...}" have now been
deprecated.
The suidperl is also considered to be too much a risk to continue maintaining
and the suidperl code is likely to be removed in a future release.
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 chdir(undef) and chdir('') behaviors to match
chdir() has been
deprecated. In future versions, chdir(undef) and chdir('') will simply fail.
Core Enhancements¶
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.
- •
- The rules for allowing underscores (underbars) in numeric
constants have been relaxed and simplified: now you can have an underscore
between digits.
- •
- GMAGIC (right-hand side magic) could in many cases such as
string concatenation be invoked too many times.
- •
- 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 subroutines
that were declared before the lexicals.
- •
- Lvalue subroutines can now return "undef" in list
context.
- •
- The "op_clear" and "op_null" are now
exported.
- •
- A new special regular expression variable has been
introduced: $^N, which contains the most-recently closed group
(submatch).
- •
- utime now supports "utime undef, undef, @files"
to change the file timestamps to the current time.
- •
- The Perl parser has been stress tested using both random
input and Markov chain input.
- •
- "eval "v200"" now works.
- •
- VMS now works under PerlIO.
- •
- END blocks are now run even if you exit/die in a BEGIN
block. 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.
Modules and Pragmata¶
New Modules and Distributions¶
- •
- Attribute::Handlers - Simpler definition of attribute
handlers
- •
- ExtUtils::Constant - generate XS code to import C header
constants
- •
- I18N::Langinfo - query locale information
- •
- I18N::LangTags - functions for dealing with RFC3066-style
language tags
- •
- libnet - a collection of perl5 modules related to network
programming
Perl installation leaves libnet unconfigured, use libnetcfg to
configure.
- •
- List::Util - selection of general-utility list
subroutines
- •
- Locale::Maketext - framework for localization
- •
- Memoize - Make your functions faster by trading space for
time
- •
- NEXT - pseudo-class for method redispatch
- •
- Scalar::Util - selection of general-utility scalar
subroutines
- •
- Test::More - yet another framework for writing test
scripts
- •
- Test::Simple - Basic utilities for writing tests
- •
- Time::HiRes - high resolution ualarm, usleep, and
gettimeofday
- •
- Time::Piece - Object Oriented time objects
(Previously known as Time::Object.)
- •
- Time::Seconds - a simple API to convert seconds to other
date values
- •
- UnicodeCD - Unicode Character Database
Updated And Improved Modules and Pragmata¶
- •
- B::Deparse module has been significantly enhanced. It now
can 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.
- •
- Class::Struct now assigns the array/hash element if the
accessor is called with an array/hash element as the sole
argument.
- •
- Cwd extension is now (even) faster.
- •
- DB_File extension has been updated to version 1.77.
- •
- Fcntl, Socket, and Sys::Syslog have been rewritten to use
the new-style constant dispatch section (see ExtUtils::Constant).
- •
- File::Find is now (again) reentrant. It also has been made
more portable.
- •
- File::Glob now supports "GLOB_LIMIT" constant to
limit the size of the returned list of filenames.
- •
- IO::Socket::INET now supports "LocalPort" of zero
(usually meaning that the operating system will make one up.)
- •
- The vars pragma now supports declaring fully qualified
variables. (Something that "our()" does not and will not
support.)
Utility Changes¶
- •
- The emacs/e2ctags.pl is now much faster.
- •
- h2ph now supports C trigraphs.
- •
- 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 constants where the first one is a prefix
of the second one, the first constant never gets 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.
- •
- libnetcfg has been added to configure the libnet.
- •
- The Pod::Html (and thusly pod2html) now allows
specifying a cache directory.
New Documentation¶
- •
- Locale::Maketext::TPJ13 is an article about software
localization, originally published in The Perl Journal #13, republished
here with kind permission.
- •
- More README.$PLATFORM files have been converted into pod,
which also means that they also be installed as perl$PLATFORM
documentation files. The new files are perlapollo, perlbeos, perldgux,
perlhurd, perlmint, perlnetware, perlplan9, perlqnx, and perltru64.
- •
- The Todo and Todo-5.6 files have been merged
into perltodo.
- •
- Use of the gprof tool to profile Perl has been
documented in perlhack. There is a make target "perl.gprof" for
generating a gprofiled Perl executable.
Installation and Configuration Improvements¶
- •
- 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.
- •
- DG/UX platform now supports the 5.005-style threads. See
perldgux.
- •
- DYNIX/ptx platform (a.k.a. dynixptx) is supported at or
near osvers 4.5.2.
- •
- Several Mac OS (Classic) portability patches have been
applied. We hope to get a fully working port by 5.8.0. (The remaining
problems relate to the changed IO model of Perl.) See perlmacos.
- •
- Mac OS X (or Darwin) should now be able to build Perl even
on HFS+ filesystems. (The case-insensitivity confused the Perl build
process.)
- •
- NetWare from Novell is now supported. See perlnetware.
- •
- The Amdahl UTS Unix mainframe platform is now
supported.
Generic Improvements¶
- •
- 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".
- •
- 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.
- •
- The Thread extension is now not built at all under ithreads
("Configure -Duseithreads") because it wouldn't work anyway (the
Thread extension requires being Configured with
"-Duse5005threads").
- •
- The "B::Deparse" compiler backend has been so
significantly improved that almost the whole Perl test suite passes after
being deparsed. A make target has been added to help in further testing:
"make test.deparse".
Selected Bug Fixes¶
- •
- The autouse pragma didn't work for
Multi::Part::Function::Names.
- •
- The behaviour of non-decimal but numeric string constants
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 using the operating system libraries in a
situation where the result of the string to number conversion is
undefined: now Perl consistently handles such strings as zero in numeric
contexts.
- •
- dprofpp -R didn't work.
- •
- PERL5OPT with embedded spaces didn't work.
- •
- Sys::Syslog ignored the "LOG_AUTH" constant.
- •
- 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.
New or Changed Diagnostics¶
- •
- In the regular expression diagnostics the "<<
HERE" marker introduced in 5.7.0 has been changed to be "<--
HERE" since too many people found the "<<" to be too
similar to here-document starters.
- •
- 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.
- •
- Certain regex modifiers such as "(?o)" make sense
only if applied to the entire regex. You will an optional warning if you
try to do otherwise.
- •
- Using arrays or hashes as references (e.g.
"%foo->{bar}" has been deprecated for a while. Now you will
get an optional warning.
Source Code Enhancements¶
MAGIC constants¶
The MAGIC constants (e.g. 'P') have been macrofied (e.g.
"PERL_MAGIC_TIED") for better source code readability and
maintainability.
perly.c,
sv.c, and
sv.h have now been extensively
commented.
Regex pre-/post-compilation items matched up¶
The regex compiler now maintains a structure that identifies 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.
gcc -Wall¶
The C code has been made much more "gcc -Wall" clean. Some warning
messages still remain, though, so if you are compiling with gcc you will see
some warnings about dubious practices. The warnings are being worked on.
New Tests¶
Several new tests have been added, especially for the
lib subsection.
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¶
Note that unlike other sections in this document (which describe changes since
5.7.0) this section is cumulative containing known problems for all the 5.7
releases.
AIX¶
- •
- 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 the 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
few random tests failing, 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 compile Perl correctly. "lslpp -L|grep vac.C" will
tell you the vac version.
Amiga Perl Invoking Mystery¶
One cannot call Perl using the "volume:" syntax, that is, "perl
-v" works, but for example "bin:perl -v" doesn't. The exact
reason is known but the current suspect is the
ixemul library.
lib/ftmp-security tests warn 'system possibly insecure'¶
Don't panic. Read INSTALL 'make test' section instead.
Cygwin intermittent failures of lib/Memoize/t/expire_file 11 and
12¶
The subtests 11 and 12 sometimes fail and sometimes work.
The lib/io_multihomed test may hang in HP-UX if Perl has been configured to be
64-bit. Because other 64-bit platforms do not hang in this test, HP-UX is
suspect. All other tests pass in 64-bit HP-UX. The test attempts to create and
connect to "multihomed" sockets (sockets which have multiple IP
addresses).
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 Sfio Fails op/misc Test 48¶
No known fix.
OS/390¶
OS/390 has rather many test failures but the situation is actually 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/B/Deparse.t 14 1 7.14% 14
../ext/B/Showlex.t 1 1 100.00% 1
../ext/Encode/Encode/Tcl.t 610 13 2.13% 592 594 596 598
600 602 604-610
../ext/IO/lib/IO/t/io_unix.t 113 28928 5 3 60.00% 3-5
../ext/POSIX/POSIX.t 29 1 3.45% 14
../ext/Storable/t/lock.t 255 65280 5 3 60.00% 3-5
../lib/locale.t 129 33024 117 19 16.24% 99-117
../lib/warnings.t 434 1 0.23% 75
../lib/ExtUtils.t 27 1 3.70% 25
../lib/Math/BigInt/t/bigintpm.t 1190 1 0.08% 1145
../lib/Unicode/UCD.t 81 48 59.26% 1-16 49-64 66-81
../lib/User/pwent.t 9 1 11.11% 4
op/pat.t 660 6 0.91% 242-243 424-425
626-627
op/split.t 0 9 ?? ?? % ??
op/taint.t 174 3 1.72% 156 162 168
op/tr.t 70 3 4.29% 50 58-59
Failed 16/422 test scripts, 96.21% okay. 105/23251 subtests failed, 99.55% okay.
op/sprintf tests 129 and 130¶
The op/sprintf tests 129 and 130 are known to fail on some platforms. Examples
include any platform using sfio, and Compaq/Tandem's NonStop-UX. The failing
platforms do not comply with the ANSI C Standard, line 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".)
Failure of Thread tests¶
Note that support for 5.005-style threading remains experimental.
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.
lib/autouse.t 4
t/lib/thr5005.t 19-20
UNICOS¶
- •
- ext/POSIX/sigaction subtests 6 and 13 may fail.
- •
- lib/ExtUtils may spuriously claim that subtest 28 failed,
which is interesting since the test only has 27 tests.
- •
- Numerous numerical test failures
op/numconvert 209,210,217,218
op/override 7
ext/Time/HiRes/HiRes 9
lib/Math/BigInt/t/bigintpm 1145
lib/Math/Trig 25
These tests fail because of yet unresolved floating point inaccuracies.
UTS¶
There are a few known test failures, see perluts.
VMS¶
Rather many tests are failing in VMS but that actually more tests succeed in VMS
than they used to, it's just that there are many, many more tests than there
used to be.
Here are the known failures from some compiler/platform combinations.
DEC C V5.3-006 on OpenVMS VAX V6.2
[-.ext.list.util.t]tainted..............FAILED on test 3
[-.ext.posix]sigaction..................FAILED on test 7
[-.ext.time.hires]hires.................FAILED on test 14
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.math.bigint.t]bigintpm...........FAILED on test 1183
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
[.op]sprintf............................FAILED on test 12
Failed 8/399 tests, 91.23% okay.
DEC C V6.0-001 on OpenVMS Alpha V7.2-1 and Compaq C V6.2-008 on OpenVMS Alpha
V7.1
[-.ext.list.util.t]tainted..............FAILED on test 3
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
Failed 4/399 tests, 92.48% okay.
Compaq C V6.4-005 on OpenVMS Alpha 7.2.1
[-.ext.b]showlex........................FAILED on test 1
[-.ext.list.util.t]tainted..............FAILED on test 3
[-.lib.file.find]taint..................FAILED on test 17
[-.lib.test.simple.t]exit...............FAILED on test 1
[.lib]vmsish............................FAILED on test 13
[.op]misc...............................FAILED on test 49
Failed 6/401 tests, 92.77% okay.
Win32¶
In multi-CPU boxes there are some problems with the I/O buffering: some output
may appear twice.
Localising a Tied Variable Leaks Memory¶
use Tie::Hash;
tie my %tie_hash => 'Tie::StdHash';
...
local($tie_hash{Foo}) = 1; # leaks
Code like the above is known to leak memory every time the
local() is
executed.
Self-tying of Arrays and Hashes Is Forbidden¶
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 for now forbidden (you will
get a fatal error even from an attempt).
Variable Attributes are not Currently Usable for Tying¶
This limitation will hopefully be fixed in future. (Subroutine attributes work
fine for tying, see Attribute::Handlers).
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 compile and work
incorrectly. Currently there is no good solution for the problem, but
Configure now provides appropriate non-largefile ccflags, ldflags, libswanted,
and libs in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the
extensions that are having problems can try configuring themselves without the
largefileness. This is admittedly not a clean solution, and the solution may
not even work at all. One potential failure is whether one can (or, if one
can, whether it's a good idea) link together at all binaries with different
ideas about file offsets, all this is platform-dependent.
The Compiler Suite Is Still Experimental¶
The compiler suite is slowly getting better but is nowhere near working order
yet.
The Long Double Support is Still Experimental¶
The ability to configure Perl's numbers to use "long doubles",
floating point numbers of hopefully better accuracy, is still experimental.
The implementations of long doubles are not yet widespread and the existing
implementations are not quite mature or standardised, therefore trying to
support them is a rare and moving target. The gain of more precision may also
be offset by slowdown in computations (more bits to move around, and the
operations are more likely to be executed by less optimised libraries).
Reporting Bugs¶
If you find what you think is a bug, you might check the articles recently
posted to the comp.lang.perl.misc newsgroup and the perl bug database at
http://bugs.perl.org/ There may also be information at
http://www.perl.com/perl/ , the Perl Home Page.
If you believe you have an unreported bug, please run the
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>, with many contributions
from The Perl Porters and Perl Users submitting feedback and patches.
Send omissions or corrections to <
perlbug@perl.org>.