NAME¶
perl5101delta - what is new for perl v5.10.1
DESCRIPTION¶
This document describes differences between the 5.10.0 release and the 5.10.1
release.
If you are upgrading from an earlier release such as 5.8.8, first read the
perl5100delta, which describes differences between 5.8.8 and 5.10.0
Incompatible Changes¶
Switch statement changes¶
The handling of complex expressions by the "given"/"when"
switch statement has been enhanced. There are two new cases where
"when" now interprets its argument as a boolean, instead of an
expression to be used in a smart match:
- flip-flop operators
- The ".." and "..." flip-flop operators
are now evaluated in boolean context, following their usual semantics; see
"Range Operators" in perlop.
Note that, as in perl 5.10.0, "when (1..10)" will not work to test
whether a given value is an integer between 1 and 10; you should use
"when ([1..10])" instead (note the array reference).
However, contrary to 5.10.0, evaluating the flip-flop operators in boolean
context ensures it can now be useful in a "when()", notably for
implementing bistable conditions, like in:
when (/^=begin/ .. /^=end/) {
# do something
}
- defined-or operator
- A compound expression involving the defined-or operator, as
in "when (expr1 // expr2)", will be treated as boolean if the
first expression is boolean. (This just extends the existing rule that
applies to the regular or operator, as in "when (expr1 ||
expr2)".)
The next section details more changes brought to the semantics to the smart
match operator, that naturally also modify the behaviour of the switch
statements where smart matching is implicitly used.
Smart match changes¶
Changes to type-based dispatch
The smart match operator "~~" is no longer commutative. The behaviour
of a smart match now depends primarily on the type of its right hand argument.
Moreover, its semantics have been adjusted for greater consistency or
usefulness in several cases. While the general backwards compatibility is
maintained, several changes must be noted:
- •
- Code references with an empty prototype are no longer
treated specially. They are passed an argument like the other code
references (even if they choose to ignore it).
- •
- "%hash ~~ sub {}" and "@array ~~ sub
{}" now test that the subroutine returns a true value for each key of
the hash (or element of the array), instead of passing the whole hash or
array as a reference to the subroutine.
- •
- Due to the commutativity breakage, code references are no
longer treated specially when appearing on the left of the "~~"
operator, but like any vulgar scalar.
- •
- "undef ~~ %hash" is always false (since
"undef" can't be a key in a hash). No implicit conversion to
"" is done (as was the case in perl 5.10.0).
- •
- "$scalar ~~ @array" now always distributes the
smart match across the elements of the array. It's true if one element in
@array verifies "$scalar ~~ $element". This is a generalization
of the old behaviour that tested whether the array contained the
scalar.
The full dispatch table for the smart match operator is given in "Smart
matching in detail" in perlsyn.
Smart match and overloading
According to the rule of dispatch based on the rightmost argument type, when an
object overloading "~~" appears on the right side of the operator,
the overload routine will always be called (with a 3rd argument set to a true
value, see overload.) However, when the object will appear on the left, the
overload routine will be called only when the rightmost argument is a simple
scalar. This way distributivity of smart match across arrays is not broken, as
well as the other behaviours with complex types (coderefs, hashes, regexes).
Thus, writers of overloading routines for smart match mostly need to worry
only with comparing against a scalar, and possibly with stringification
overloading; the other common cases will be automatically handled
consistently.
"~~" will now refuse to work on objects that do not overload it (in
order to avoid relying on the object's underlying structure). (However, if the
object overloads the stringification or the numification operators, and if
overload fallback is active, it will be used instead, as usual.)
Other incompatible changes¶
- •
- The semantics of "use feature :5.10*" have
changed slightly. See "Modules and Pragmata" for more
information.
- •
- It is now a run-time error to use the smart match operator
"~~" with an object that has no overload defined for it. (This
way "~~" will not break encapsulation by matching against the
object's internal representation as a reference.)
- •
- The version control system used for the development of the
perl interpreter has been switched from Perforce to git. This is mainly an
internal issue that only affects people actively working on the perl core;
but it may have minor external visibility, for example in some of details
of the output of "perl -V". See perlrepository for more
information.
- •
- The internal structure of the "ext/" directory in
the perl source has been reorganised. In general, a module
"Foo::Bar" whose source was stored under ext/Foo/Bar/ is
now located under ext/Foo-Bar/. Also, some modules have been moved
from lib/ to ext/. This is purely a source tarball change,
and should make no difference to the compilation or installation of perl,
unless you have a very customised build process that explicitly relies on
this structure, or which hard-codes the "nonxs_ext"
Configure parameter. Specifically, this change does not by default
alter the location of any files in the final installation.
- •
- As part of the "Test::Harness" 2.x to 3.x
upgrade, the experimental "Test::Harness::Straps" module has
been removed. See "Updated Modules" for more details.
- •
- As part of the "ExtUtils::MakeMaker" upgrade, the
"ExtUtils::MakeMaker::bytes" and
"ExtUtils::MakeMaker::vmsish" modules have been removed from
this distribution.
- •
- "Module::CoreList" no longer contains the
%:patchlevel hash.
- •
- This one is actually a change introduced in 5.10.0, but it
was missed from that release's perldelta, so it is mentioned here instead.
A bugfix related to the handling of the "/m" modifier and
"qr" resulted in a change of behaviour between 5.8.x and 5.10.0:
# matches in 5.8.x, doesn't match in 5.10.0
$re = qr/^bar/; "foo\nbar" =~ /$re/m;
Core Enhancements¶
Unicode Character Database 5.1.0¶
The copy of the Unicode Character Database included in Perl 5.10.1 has been
updated to 5.1.0 from 5.0.0. See
<
http://www.unicode.org/versions/Unicode5.1.0/#Notable_Changes> for the
notable changes.
A proper interface for pluggable Method Resolution Orders¶
As of Perl 5.10.1 there is a new interface for plugging and using method
resolution orders other than the default (linear depth first search). The C3
method resolution order added in 5.10.0 has been re-implemented as a plugin,
without changing its Perl-space interface. See perlmroapi for more
information.
The "overloading" pragma¶
This pragma allows you to lexically disable or enable overloading for some or
all operations. (Yuval Kogman)
Parallel tests¶
The core distribution can now run its regression tests in parallel on Unix-like
platforms. Instead of running "make test", set "TEST_JOBS"
in your environment to the number of tests to run in parallel, and run
"make test_harness". On a Bourne-like shell, this can be done as
TEST_JOBS=3 make test_harness # Run 3 tests in parallel
An environment variable is used, rather than parallel make itself, because
TAP::Harness needs to be able to schedule individual non-conflicting test
scripts itself, and there is no standard interface to "make"
utilities to interact with their job schedulers.
Note that currently some test scripts may fail when run in parallel (most
notably "ext/IO/t/io_dir.t"). If necessary run just the failing
scripts again sequentially and see if the failures go away.
DTrace support¶
Some support for DTrace has been added. See "DTrace support" in
INSTALL.
Both "CPAN" and "CPANPLUS" now support the
"configure_requires" keyword in the "META.yml" metadata
file included in most recent CPAN distributions. This allows distribution
authors to specify configuration prerequisites that must be installed before
running
Makefile.PL or
Build.PL.
See the documentation for "ExtUtils::MakeMaker" or
"Module::Build" for more on how to specify
"configure_requires" when creating a distribution for CPAN.
Modules and Pragmata¶
New Modules and Pragmata¶
- "autodie"
- This is a new lexically-scoped alternative for the
"Fatal" module. The bundled version is 2.06_01. Note that in
this release, using a string eval when "autodie" is in effect
can cause the autodie behaviour to leak into the surrounding scope. See
"BUGS" in autodie for more details.
- "Compress::Raw::Bzip2"
- This has been added to the core (version 2.020).
- "parent"
- This pragma establishes an ISA relationship with base
classes at compile time. It provides the key feature of "base"
without the feature creep.
- "Parse::CPAN::Meta"
- This has been added to the core (version 1.39).
Pragmata Changes¶
- "attributes"
- Upgraded from version 0.08 to 0.09.
- "attrs"
- Upgraded from version 1.02 to 1.03.
- "base"
- Upgraded from version 2.13 to 2.14. See parent for a
replacement.
- "bigint"
- Upgraded from version 0.22 to 0.23.
- "bignum"
- Upgraded from version 0.22 to 0.23.
- "bigrat"
- Upgraded from version 0.22 to 0.23.
- "charnames"
- Upgraded from version 1.06 to 1.07.
The Unicode NameAliases.txt database file has been added. This has
the effect of adding some extra "\N" character names that
formerly wouldn't have been recognised; for example, "\N{LATIN
CAPITAL LETTER GHA}".
- "constant"
- Upgraded from version 1.13 to 1.17.
- "feature"
- The meaning of the ":5.10" and
":5.10.X" feature bundles has changed slightly. The last
component, if any (i.e. "X") is simply ignored. This is
predicated on the assumption that new features will not, in general, be
added to maintenance releases. So ":5.10" and
":5.10.X" have identical effect. This is a change to the
behaviour documented for 5.10.0.
- "fields"
- Upgraded from version 2.13 to 2.14 (this was just a version
bump; there were no functional changes).
- "lib"
- Upgraded from version 0.5565 to 0.62.
- "open"
- Upgraded from version 1.06 to 1.07.
- "overload"
- Upgraded from version 1.06 to 1.07.
- "overloading"
- See "The "overloading" pragma"
above.
- "version"
- Upgraded from version 0.74 to 0.77.
Updated Modules¶
- "Archive::Extract"
- Upgraded from version 0.24 to 0.34.
- "Archive::Tar"
- Upgraded from version 1.38 to 1.52.
- "Attribute::Handlers"
- Upgraded from version 0.79 to 0.85.
- "AutoLoader"
- Upgraded from version 5.63 to 5.68.
- "AutoSplit"
- Upgraded from version 1.05 to 1.06.
- "B"
- Upgraded from version 1.17 to 1.22.
- "B::Debug"
- Upgraded from version 1.05 to 1.11.
- "B::Deparse"
- Upgraded from version 0.83 to 0.89.
- "B::Lint"
- Upgraded from version 1.09 to 1.11.
- "B::Xref"
- Upgraded from version 1.01 to 1.02.
- "Benchmark"
- Upgraded from version 1.10 to 1.11.
- "Carp"
- Upgraded from version 1.08 to 1.11.
- "CGI"
- Upgraded from version 3.29 to 3.43. (also includes the
"default_value for popup_menu()" fix from 3.45).
- "Compress::Zlib"
- Upgraded from version 2.008 to 2.020.
- "CPAN"
- Upgraded from version 1.9205 to 1.9402.
"CPAN::FTP" has a local fix to stop it being too verbose on
download failure.
- "CPANPLUS"
- Upgraded from version 0.84 to 0.88.
- "CPANPLUS::Dist::Build"
- Upgraded from version 0.06_02 to 0.36.
- "Cwd"
- Upgraded from version 3.25_01 to 3.30.
- "Data::Dumper"
- Upgraded from version 2.121_14 to 2.124.
- "DB"
- Upgraded from version 1.01 to 1.02.
- "DB_File"
- Upgraded from version 1.816_1 to 1.820.
- "Devel::PPPort"
- Upgraded from version 3.13 to 3.19.
- "Digest::MD5"
- Upgraded from version 2.36_01 to 2.39.
- "Digest::SHA"
- Upgraded from version 5.45 to 5.47.
- "DirHandle"
- Upgraded from version 1.01 to 1.03.
- "Dumpvalue"
- Upgraded from version 1.12 to 1.13.
- "DynaLoader"
- Upgraded from version 1.08 to 1.10.
- "Encode"
- Upgraded from version 2.23 to 2.35.
- "Errno"
- Upgraded from version 1.10 to 1.11.
- "Exporter"
- Upgraded from version 5.62 to 5.63.
- "ExtUtils::CBuilder"
- Upgraded from version 0.21 to 0.2602.
- "ExtUtils::Command"
- Upgraded from version 1.13 to 1.16.
- "ExtUtils::Constant"
- Upgraded from 0.20 to 0.22. (Note that neither of these
versions are available on CPAN.)
- "ExtUtils::Embed"
- Upgraded from version 1.27 to 1.28.
- "ExtUtils::Install"
- Upgraded from version 1.44 to 1.54.
- "ExtUtils::MakeMaker"
- Upgraded from version 6.42 to 6.55_02.
Note that "ExtUtils::MakeMaker::bytes" and
"ExtUtils::MakeMaker::vmsish" have been removed from this
distribution.
- "ExtUtils::Manifest"
- Upgraded from version 1.51_01 to 1.56.
- "ExtUtils::ParseXS"
- Upgraded from version 2.18_02 to 2.2002.
- "Fatal"
- Upgraded from version 1.05 to 2.06_01. See also the new
pragma "autodie".
- "File::Basename"
- Upgraded from version 2.76 to 2.77.
- "File::Compare"
- Upgraded from version 1.1005 to 1.1006.
- "File::Copy"
- Upgraded from version 2.11 to 2.14.
- "File::Fetch"
- Upgraded from version 0.14 to 0.20.
- "File::Find"
- Upgraded from version 1.12 to 1.14.
- "File::Path"
- Upgraded from version 2.04 to 2.07_03.
- "File::Spec"
- Upgraded from version 3.2501 to 3.30.
- "File::stat"
- Upgraded from version 1.00 to 1.01.
- "File::Temp"
- Upgraded from version 0.18 to 0.22.
- "FileCache"
- Upgraded from version 1.07 to 1.08.
- "FileHandle"
- Upgraded from version 2.01 to 2.02.
- "Filter::Simple"
- Upgraded from version 0.82 to 0.84.
- "Filter::Util::Call"
- Upgraded from version 1.07 to 1.08.
- "FindBin"
- Upgraded from version 1.49 to 1.50.
- "GDBM_File"
- Upgraded from version 1.08 to 1.09.
- "Getopt::Long"
- Upgraded from version 2.37 to 2.38.
- "Hash::Util::FieldHash"
- Upgraded from version 1.03 to 1.04. This fixes a memory
leak.
- "I18N::Collate"
- Upgraded from version 1.00 to 1.01.
- "IO"
- Upgraded from version 1.23_01 to 1.25.
This makes non-blocking mode work on Windows in "IO::Socket::INET"
[CPAN #43573].
- "IO::Compress::*"
- Upgraded from version 2.008 to 2.020.
- "IO::Dir"
- Upgraded from version 1.06 to 1.07.
- "IO::Handle"
- Upgraded from version 1.27 to 1.28.
- "IO::Socket"
- Upgraded from version 1.30_01 to 1.31.
- "IO::Zlib"
- Upgraded from version 1.07 to 1.09.
- "IPC::Cmd"
- Upgraded from version 0.40_1 to 0.46.
- "IPC::Open3"
- Upgraded from version 1.02 to 1.04.
- "IPC::SysV"
- Upgraded from version 1.05 to 2.01.
- "lib"
- Upgraded from version 0.5565 to 0.62.
- "List::Util"
- Upgraded from version 1.19 to 1.21.
- "Locale::MakeText"
- Upgraded from version 1.12 to 1.13.
- "Log::Message"
- Upgraded from version 0.01 to 0.02.
- "Math::BigFloat"
- Upgraded from version 1.59 to 1.60.
- "Math::BigInt"
- Upgraded from version 1.88 to 1.89.
- "Math::BigInt::FastCalc"
- Upgraded from version 0.16 to 0.19.
- "Math::BigRat"
- Upgraded from version 0.21 to 0.22.
- "Math::Complex"
- Upgraded from version 1.37 to 1.56.
- "Math::Trig"
- Upgraded from version 1.04 to 1.20.
- "Memoize"
- Upgraded from version 1.01_02 to 1.01_03 (just a minor
documentation change).
- "Module::Build"
- Upgraded from version 0.2808_01 to 0.34_02.
- "Module::CoreList"
- Upgraded from version 2.13 to 2.18. This release no longer
contains the %Module::CoreList::patchlevel hash.
- "Module::Load"
- Upgraded from version 0.12 to 0.16.
- "Module::Load::Conditional"
- Upgraded from version 0.22 to 0.30.
- "Module::Loaded"
- Upgraded from version 0.01 to 0.02.
- "Module::Pluggable"
- Upgraded from version 3.6 to 3.9.
- "NDBM_File"
- Upgraded from version 1.07 to 1.08.
- "Net::Ping"
- Upgraded from version 2.33 to 2.36.
- "NEXT"
- Upgraded from version 0.60_01 to 0.64.
- "Object::Accessor"
- Upgraded from version 0.32 to 0.34.
- "OS2::REXX"
- Upgraded from version 1.03 to 1.04.
- "Package::Constants"
- Upgraded from version 0.01 to 0.02.
- "PerlIO"
- Upgraded from version 1.04 to 1.06.
- "PerlIO::via"
- Upgraded from version 0.04 to 0.07.
- "Pod::Man"
- Upgraded from version 2.16 to 2.22.
- "Pod::Parser"
- Upgraded from version 1.35 to 1.37.
- "Pod::Simple"
- Upgraded from version 3.05 to 3.07.
- "Pod::Text"
- Upgraded from version 3.08 to 3.13.
- "POSIX"
- Upgraded from version 1.13 to 1.17.
- "Safe"
- Upgraded from 2.12 to 2.18.
- "Scalar::Util"
- Upgraded from version 1.19 to 1.21.
- "SelectSaver"
- Upgraded from 1.01 to 1.02.
- "SelfLoader"
- Upgraded from 1.11 to 1.17.
- "Socket"
- Upgraded from 1.80 to 1.82.
- "Storable"
- Upgraded from 2.18 to 2.20.
- "Switch"
- Upgraded from version 2.13 to 2.14. Please see
"Deprecations".
- "Symbol"
- Upgraded from version 1.06 to 1.07.
- "Sys::Syslog"
- Upgraded from version 0.22 to 0.27.
- "Term::ANSIColor"
- Upgraded from version 1.12 to 2.00.
- "Term::ReadLine"
- Upgraded from version 1.03 to 1.04.
- "Term::UI"
- Upgraded from version 0.18 to 0.20.
- "Test::Harness"
- Upgraded from version 2.64 to 3.17.
Note that one side-effect of the 2.x to 3.x upgrade is that the experimental
"Test::Harness::Straps" module (and its supporting
"Assert", "Iterator", "Point" and
"Results" modules) have been removed. If you still need this,
then they are available in the (unmaintained)
"Test-Harness-Straps" distribution on CPAN.
- "Test::Simple"
- Upgraded from version 0.72 to 0.92.
- "Text::ParseWords"
- Upgraded from version 3.26 to 3.27.
- "Text::Tabs"
- Upgraded from version 2007.1117 to 2009.0305.
- "Text::Wrap"
- Upgraded from version 2006.1117 to 2009.0305.
- "Thread::Queue"
- Upgraded from version 2.00 to 2.11.
- "Thread::Semaphore"
- Upgraded from version 2.01 to 2.09.
- "threads"
- Upgraded from version 1.67 to 1.72.
- "threads::shared"
- Upgraded from version 1.14 to 1.29.
- "Tie::RefHash"
- Upgraded from version 1.37 to 1.38.
- "Tie::StdHandle"
- This has documentation changes, and has been assigned a
version for the first time: version 4.2.
- "Time::HiRes"
- Upgraded from version 1.9711 to 1.9719.
- "Time::Local"
- Upgraded from version 1.18 to 1.1901.
- "Time::Piece"
- Upgraded from version 1.12 to 1.15.
- "Unicode::Normalize"
- Upgraded from version 1.02 to 1.03.
- "Unicode::UCD"
- Upgraded from version 0.25 to 0.27.
"charinfo()" now works on Unified CJK code points added to later
versions of Unicode.
"casefold()" has new fields returned to provide both a simpler
interface and previously missing information. The old fields are retained
for backwards compatibility. Information about Turkic-specific code points
is now returned.
The documentation has been corrected and expanded.
- "UNIVERSAL"
- Upgraded from version 1.04 to 1.05.
- "Win32"
- Upgraded from version 0.34 to 0.39.
- "Win32API::File"
- Upgraded from version 0.1001_01 to 0.1101.
- "XSLoader"
- Upgraded from version 0.08 to 0.10.
Utility Changes¶
- h2ph
- Now looks in "include-fixed" too, which is a
recent addition to gcc's search path.
- h2xs
- No longer incorrectly treats enum values like macros
(Daniel Burr).
Now handles C++ style constants ("//") properly in enums. (A patch
from Rainer Weikusat was used; Daniel Burr also proposed a similar
fix).
- perl5db.pl
- "LVALUE" subroutines now work under the debugger.
The debugger now correctly handles proxy constant subroutines, and
subroutine stubs.
- perlthanks
- Perl 5.10.1 adds a new utility perlthanks, which is
a variant of perlbug, but for sending non-bug-reports to the
authors and maintainers of Perl. Getting nothing but bug reports can
become a bit demoralising: we'll see if this changes things.
New Documentation¶
- perlhaiku
- This contains instructions on how to build perl for the
Haiku platform.
- perlmroapi
- This describes the new interface for pluggable Method
Resolution Orders.
- perlperf
- This document, by Richard Foley, provides an introduction
to the use of performance and optimization techniques which can be used
with particular reference to perl programs.
- perlrepository
- This describes how to access the perl source using the
git version control system.
- perlthanks
- This describes the new perlthanks utility.
Changes to Existing Documentation¶
The various large "Changes*" files (which listed every change made to
perl over the last 18 years) have been removed, and replaced by a small file,
also called "Changes", which just explains how that same information
may be extracted from the git version control system.
The file
Porting/patching.pod has been deleted, as it mainly described
interacting with the old Perforce-based repository, which is now obsolete.
Information still relevant has been moved to perlrepository.
perlapi, perlintern, perlmodlib and perltoc are now all generated at build time,
rather than being shipped as part of the release.
- •
- A new internal cache means that "isa()" will
often be faster.
- •
- Under "use locale", the locale-relevant
information is now cached on read-only values, such as the list returned
by "keys %hash". This makes operations such as "sort keys
%hash" in the scope of "use locale" much faster.
- •
- Empty "DESTROY" methods are no longer
called.
Installation and Configuration Improvements¶
ext/ reorganisation¶
The layout of directories in
ext has been revised. Specifically, all
extensions are now flat, and at the top level, with "/" in pathnames
replaced by "-", so that
ext/Data/Dumper/ is now
ext/Data-Dumper/, etc. The names of the extensions as specified to
Configure, and as reported by %Config::Config under the keys
"dynamic_ext", "known_extensions", "nonxs_ext"
and "static_ext" have not changed, and still use "/".
Hence this change will not have any affect once perl is installed. However,
"Attribute::Handlers", "Safe" and "mro" have now
become extensions in their own right, so if you run
Configure with
options to specify an exact list of extensions to build, you will need to
change it to account for this.
For 5.10.2, it is planned that many dual-life modules will have been moved from
lib to
ext; again this will have no effect on an installed perl,
but will matter if you invoke
Configure with a pre-canned list of
extensions to build.
Configuration improvements¶
If "vendorlib" and "vendorarch" are the same, then they are
only added to @INC once.
$Config{usedevel} and the C-level "PERL_USE_DEVEL" are now defined if
perl is built with "-Dusedevel".
Configure will enable use of "-fstack-protector", to provide
protection against stack-smashing attacks, if the compiler supports it.
Configure will now determine the correct prototypes for re-entrant
functions, and for "gconvert", if you are using a C++ compiler
rather than a C compiler.
On Unix, if you build from a tree containing a git repository, the configuration
process will note the commit hash you have checked out, for display in the
output of "perl -v" and "perl -V". Unpushed local commits
are automatically added to the list of local patches displayed by "perl
-V".
Compilation improvements¶
As part of the flattening of
ext, all extensions on all platforms are
built by
make_ext.pl. This replaces the Unix-specific
ext/util/make_ext, VMS-specific
make_ext.com and Win32-specific
win32/buildext.pl.
- AIX
- Removed libbsd for AIX 5L and 6.1. Only
flock() was used from libbsd.
Removed libgdbm for AIX 5L and 6.1. The libgdbm is delivered
as an optional package with the AIX Toolbox. Unfortunately the 64 bit
version is broken.
Hints changes mean that AIX 4.2 should work again.
- Cygwin
- On Cygwin we now strip the last number from the DLL. This
has been the behaviour in the cygwin.com build for years. The hints files
have been updated.
- FreeBSD
- The hints files now identify the correct threading
libraries on FreeBSD 7 and later.
- Irix
- We now work around a bizarre preprocessor bug in the Irix
6.5 compiler: "cc -E -" unfortunately goes into K&R mode,
but "cc -E file.c" doesn't.
- Haiku
- Patches from the Haiku maintainers have been merged in.
Perl should now build on Haiku.
- MirOS BSD
- Perl should now build on MirOS BSD.
- NetBSD
- Hints now supports versions 5.*.
- Stratus VOS
- Various changes from Stratus have been merged in.
- Symbian
- There is now support for Symbian S60 3.2 SDK and S60 5.0
SDK.
- Win32
- Improved message window handling means that
"alarm" and "kill" messages will no longer be dropped
under race conditions.
- VMS
- Reads from the in-memory temporary files of
"PerlIO::scalar" used to fail if $/ was set to a numeric
reference (to indicate record-style reads). This is now fixed.
VMS now supports "getgrgid".
Many improvements and cleanups have been made to the VMS file name handling
and conversion code.
Enabling the "PERL_VMS_POSIX_EXIT" logical name now encodes a
POSIX exit status in a VMS condition value for better interaction with
GNV's bash shell and other utilities that depend on POSIX exit values. See
"$?" in perlvms for details.
Selected Bug Fixes¶
- •
- 5.10.0 inadvertently disabled an optimisation, which caused
a measurable performance drop in list assignment, such as is often used to
assign function parameters from @_. The optimisation has been re-instated,
and the performance regression fixed.
- •
- Fixed memory leak on "while (1) { map 1, 1 }" [RT
#53038].
- •
- Some potential coredumps in PerlIO fixed [RT
#57322,54828].
- •
- The debugger now works with lvalue subroutines.
- •
- The debugger's "m" command was broken on modules
that defined constants [RT #61222].
- •
- "crypt()" and string complement could return
tainted values for untainted arguments [RT #59998].
- •
- The "-i.suffix" command-line switch now recreates
the file using restricted permissions, before changing its mode to match
the original file. This eliminates a potential race condition [RT
#60904].
- •
- On some Unix systems, the value in $? would not have the
top bit set ("$? & 128") even if the child core dumped.
- •
- Under some circumstances, $^R could incorrectly become
undefined [RT #57042].
- •
- (XS) In various hash functions, passing a pre-computed hash
to when the key is UTF-8 might result in an incorrect lookup.
- •
- (XS) Including XSUB.h before perl.h gave a
compile-time error [RT #57176].
- •
- "$object->isa('Foo')" would report false if
the package "Foo" didn't exist, even if the object's @ISA
contained "Foo".
- •
- Various bugs in the new-to 5.10.0 mro code, triggered by
manipulating @ISA, have been found and fixed.
- •
- Bitwise operations on references could crash the
interpreter, e.g. "$x=\$y; $x |= "foo"" [RT
#54956].
- •
- Patterns including alternation might be sensitive to the
internal UTF-8 representation, e.g.
my $byte = chr(192);
my $utf8 = chr(192); utf8::upgrade($utf8);
$utf8 =~ /$byte|X}/i; # failed in 5.10.0
- •
- Within UTF8-encoded Perl source files (i.e. where "use
utf8" is in effect), double-quoted literal strings could be corrupted
where a "\xNN", "\0NNN" or "\N{}" is
followed by a literal character with ordinal value greater than 255 [RT
#59908].
- •
- "B::Deparse" failed to correctly deparse various
constructs: "readpipe STRING" [RT #62428],
"CORE::require(STRING)" [RT #62488], "sub foo(_)" [RT
#62484].
- •
- Using "setpgrp()" with no arguments could corrupt
the perl stack.
- •
- The block form of "eval" is now specifically
trappable by "Safe" and "ops". Previously it was
erroneously treated like string "eval".
- •
- In 5.10.0, the two characters "[~" were sometimes
parsed as the smart match operator ("~~") [RT #63854].
- •
- In 5.10.0, the "*" quantifier in patterns was
sometimes treated as "{0,32767}" [RT #60034, #60464]. For
example, this match would fail:
("ab" x 32768) =~ /^(ab)*$/
- •
- "shmget" was limited to a 32 bit segment size on
a 64 bit OS [RT #63924].
- •
- Using "next" or "last" to exit a
"given" block no longer produces a spurious warning like the
following:
Exiting given via last at foo.pl line 123
- •
- On Windows, '.\foo' and '..\foo' were treated differently
than './foo' and '../foo' by "do" and "require" [RT
#63492].
- •
- Assigning a format to a glob could corrupt the format;
e.g.:
*bar=*foo{FORMAT}; # foo format now bad
- •
- Attempting to coerce a typeglob to a string or number could
cause an assertion failure. The correct error message is now generated,
"Can't coerce GLOB to $type".
- •
- Under "use filetest 'access'", "-x" was
using the wrong access mode. This has been fixed [RT #49003].
- •
- "length" on a tied scalar that returned a Unicode
value would not be correct the first time. This has been fixed.
- •
- Using an array "tie" inside in array
"tie" could SEGV. This has been fixed. [RT #51636]
- •
- A race condition inside "PerlIOStdio_close()" has
been identified and fixed. This used to cause various threading issues,
including SEGVs.
- •
- In "unpack", the use of "()" groups in
scalar context was internally placing a list on the interpreter's stack,
which manifested in various ways, including SEGVs. This is now fixed [RT
#50256].
- •
- Magic was called twice in "substr",
"\&$x", "tie $x, $m" and "chop". These
have all been fixed.
- •
- A 5.10.0 optimisation to clear the temporary stack within
the implicit loop of "s///ge" has been reverted, as it turned
out to be the cause of obscure bugs in seemingly unrelated parts of the
interpreter [commit ef0d4e17921ee3de].
- •
- The line numbers for warnings inside "elsif" are
now correct.
- •
- The ".." operator now works correctly with ranges
whose ends are at or close to the values of the smallest and largest
integers.
- •
- "binmode STDIN, ':raw'" could lead to
segmentation faults on some platforms. This has been fixed [RT
#54828].
- •
- An off-by-one error meant that "index $str, ..."
was effectively being executed as "index "$str\0",
...". This has been fixed [RT #53746].
- •
- Various leaks associated with named captures in regexes
have been fixed [RT #57024].
- •
- A weak reference to a hash would leak. This was affecting
"DBI" [RT #56908].
- •
- Using (?|) in a regex could cause a segfault [RT
#59734].
- •
- Use of a UTF-8 "tr//" within a closure could
cause a segfault [RT #61520].
- •
- Calling "sv_chop()" or otherwise upgrading an SV
could result in an unaligned 64-bit access on the SPARC architecture [RT
#60574].
- •
- In the 5.10.0 release, "inc_version_list" would
incorrectly list "5.10.*" after "5.8.*"; this affected
the @INC search order [RT #67628].
- •
- In 5.10.0, "pack "a*", $tainted_value"
returned a non-tainted value [RT #52552].
- •
- In 5.10.0, "printf" and "sprintf" could
produce the fatal error "panic: utf8_mg_pos_cache_update" when
printing UTF-8 strings [RT #62666].
- •
- In the 5.10.0 release, a dynamically created
"AUTOLOAD" method might be missed (method cache issue) [RT
#60220,60232].
- •
- In the 5.10.0 release, a combination of "use
feature" and "//ee" could cause a memory leak [RT
#63110].
- •
- "-C" on the shebang ("#!") line is once
more permitted if it is also specified on the command line. "-C"
on the shebang line used to be a silent no-op if it was not also on
the command line, so perl 5.10.0 disallowed it, which broke some scripts.
Now perl checks whether it is also on the command line and only dies if it
is not [RT #67880].
- •
- In 5.10.0, certain types of re-entrant regular expression
could crash, or cause the following assertion failure [RT #60508]:
Assertion rx->sublen >= (s - rx->subbeg) + i failed
New or Changed Diagnostics¶
- "panic: sv_chop %s"
- This new fatal error occurs when the C routine
"Perl_sv_chop()" was passed a position that is not within the
scalar's string buffer. This could be caused by buggy XS code, and at this
point recovery is not possible.
- "Can't locate package %s for the parents of
%s"
- This warning has been removed. In general, it only got
produced in conjunction with other warnings, and removing it allowed an
ISA lookup optimisation to be added.
- "v-string in use/require is non-portable"
- This warning has been removed.
- "Deep recursion on subroutine
"%s""
- It is now possible to change the depth threshold for this
warning from the default of 100, by recompiling the perl binary,
setting the C pre-processor macro "PERL_SUB_DEPTH_WARN" to the
desired value.
Changed Internals¶
- •
- The J.R.R. Tolkien quotes at the head of C source file have
been checked and proper citations added, thanks to a patch from Tom
Christiansen.
- •
- "vcroak()" now accepts a null first argument. In
addition, a full audit was made of the "not NULL" compiler
annotations, and those for several other internal functions were
corrected.
- •
- New macros "dSAVEDERRNO",
"dSAVE_ERRNO", "SAVE_ERRNO", "RESTORE_ERRNO"
have been added to formalise the temporary saving of the "errno"
variable.
- •
- The function "Perl_sv_insert_flags" has been
added to augment "Perl_sv_insert".
- •
- The function "Perl_newSV_type(type)" has been
added, equivalent to "Perl_newSV()" followed by
"Perl_sv_upgrade(type)".
- •
- The function "Perl_newSVpvn_flags()" has been
added, equivalent to "Perl_newSVpvn()" and then performing the
action relevant to the flag.
Two flag bits are currently supported.
- "SVf_UTF8"
- This will call "SvUTF8_on()" for you. (Note that
this does not convert an sequence of ISO 8859-1 characters to UTF-8). A
wrapper, "newSVpvn_utf8()" is available for this.
- "SVs_TEMP"
- Call "sv_2mortal()" on the new SV.
There is also a wrapper that takes constant strings,
"newSVpvs_flags()".
- •
- The function "Perl_croak_xs_usage" has been added
as a wrapper to "Perl_croak".
- •
- The functions "PerlIO_find_layer" and
"PerlIO_list_alloc" are now exported.
- •
- "PL_na" has been exterminated from the core code,
replaced by local STRLEN temporaries, or "*_nolen()" calls.
Either approach is faster than "PL_na", which is a pointer
deference into the interpreter structure under ithreads, and a global
variable otherwise.
- •
- "Perl_mg_free()" used to leave freed memory
accessible via SvMAGIC() on the scalar. It now updates the linked
list to remove each piece of magic as it is freed.
- •
- Under ithreads, the regex in "PL_reg_curpm" is
now reference counted. This eliminates a lot of hackish workarounds to
cope with it not being reference counted.
- •
- "Perl_mg_magical()" would sometimes incorrectly
turn on "SvRMAGICAL()". This has been fixed.
- •
- The public IV and NV flags are now not set if the
string value has trailing "garbage". This behaviour is
consistent with not setting the public IV or NV flags if the value is out
of range for the type.
- •
- SV allocation tracing has been added to the diagnostics
enabled by "-Dm". The tracing can alternatively output via the
"PERL_MEM_LOG" mechanism, if that was enabled when the
perl binary was compiled.
- •
- Uses of "Nullav", "Nullcv",
"Nullhv", "Nullop", "Nullsv" etc have been
replaced by "NULL" in the core code, and non-dual-life modules,
as "NULL" is clearer to those unfamiliar with the core
code.
- •
- A macro MUTABLE_PTR(p) has been added, which on
(non-pedantic) gcc will not cast away "const", returning a
"void *". Macros "MUTABLE_SV(av)",
"MUTABLE_SV(cv)" etc build on this, casting to "AV *"
etc without casting away "const". This allows proper
compile-time auditing of "const" correctness in the core, and
helped picked up some errors (now fixed).
- •
- Macros "mPUSHs()" and "mXPUSHs()" have
been added, for pushing SVs on the stack and mortalizing them.
- •
- Use of the private structure "mro_meta" has
changed slightly. Nothing outside the core should be accessing this
directly anyway.
- •
- A new tool, "Porting/expand-macro.pl" has been
added, that allows you to view how a C preprocessor macro would be
expanded when compiled. This is handy when trying to decode the macro hell
that is the perl guts.
New Tests¶
Many modules updated from CPAN incorporate new tests.
Several tests that have the potential to hang forever if they fail now
incorporate a "watchdog" functionality that will kill them after a
timeout, which helps ensure that "make test" and "make
test_harness" run to completion automatically. (Jerry Hedden).
Some core-specific tests have been added:
- t/comp/retainedlines.t
- Check that the debugger can retain source lines from
"eval".
- t/io/perlio_fail.t
- Check that bad layers fail.
- t/io/perlio_leaks.t
- Check that PerlIO layers are not leaking.
- t/io/perlio_open.t
- Check that certain special forms of open work.
- t/io/perlio.t
- General PerlIO tests.
- t/io/pvbm.t
- Check that there is no unexpected interaction between the
internal types "PVBM" and "PVGV".
- t/mro/package_aliases.t
- Check that mro works properly in the presence of aliased
packages.
- t/op/dbm.t
- Tests for "dbmopen" and
"dbmclose".
- t/op/index_thr.t
- Tests for the interaction of "index" and
threads.
- t/op/pat_thr.t
- Tests for the interaction of esoteric patterns and
threads.
- t/op/qr_gc.t
- Test that "qr" doesn't leak.
- t/op/reg_email_thr.t
- Tests for the interaction of regex recursion and
threads.
- t/op/regexp_qr_embed_thr.t
- Tests for the interaction of patterns with embedded
"qr//" and threads.
- t/op/regexp_unicode_prop.t
- Tests for Unicode properties in regular expressions.
- t/op/regexp_unicode_prop_thr.t
- Tests for the interaction of Unicode properties and
threads.
- t/op/reg_nc_tie.t
- Test the tied methods of
"Tie::Hash::NamedCapture".
- t/op/reg_posixcc.t
- Check that POSIX character classes behave
consistently.
- t/op/re.t
- Check that exportable "re" functions in
universal.c work.
- t/op/setpgrpstack.t
- Check that "setpgrp" works.
- t/op/substr_thr.t
- Tests for the interaction of "substr" and
threads.
- t/op/upgrade.t
- Check that upgrading and assigning scalars works.
- t/uni/lex_utf8.t
- Check that Unicode in the lexer works.
- t/uni/tie.t
- Check that Unicode and "tie" work.
Known Problems¶
This is a list of some significant unfixed bugs, which are regressions from
either 5.10.0 or 5.8.x.
- •
- "List::Util::first" misbehaves in the presence of
a lexical $_ (typically introduced by "my $_" or implicitly by
"given"). The variable which gets set for each iteration is the
package variable $_, not the lexical $_ [RT #67694].
A similar issue may occur in other modules that provide functions which take
a block as their first argument, like
foo { ... $_ ...} list
- •
- The "charnames" pragma may generate a run-time
error when a regex is interpolated [RT #56444]:
use charnames ':full';
my $r1 = qr/\N{THAI CHARACTER SARA I}/;
"foo" =~ $r1; # okay
"foo" =~ /$r1+/; # runtime error
A workaround is to generate the character outside of the regex:
my $a = "\N{THAI CHARACTER SARA I}";
my $r1 = qr/$a/;
- •
- Some regexes may run much more slowly when run in a child
thread compared with the thread the pattern was compiled into [RT
#55600].
Deprecations¶
The following items are now deprecated.
- •
- "Switch" is buggy and should be avoided. From
perl 5.11.0 onwards, it is intended that any use of the core version of
this module will emit a warning, and that the module will eventually be
removed from the core (probably in perl 5.14.0). See "Switch
statements" in perlsyn for its replacement.
- •
- "suidperl" will be removed in 5.12.0. This
provides a mechanism to emulate setuid permission bits on systems that
don't support it properly.
Acknowledgements¶
Some of the work in this release was funded by a TPF grant.
Nicholas Clark officially retired from maintenance pumpking duty at the end of
2008; however in reality he has put much effort in since then to help get
5.10.1 into a fit state to be released, including writing a considerable chunk
of this perldelta.
Steffen Mueller and David Golden in particular helped getting CPAN modules
polished and synchronised with their in-core equivalents.
Craig Berry was tireless in getting maint to run under VMS, no matter how many
times we broke it for him.
The other core committers contributed most of the changes, and applied most of
the patches sent in by the hundreds of contributors listed in
AUTHORS.
(Sorry to all the people I haven't mentioned by name).
Finally, thanks to Larry Wall, without whom none of this would be necessary.
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://rt.perl.org/perlbug/ . There may also be information at
http://www.perl.org/ , 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.
If the bug you are reporting has security implications, which make it
inappropriate to send to a publicly archived mailing list, then please send it
to perl5-security-report@perl.org. This points to a closed subscription
unarchived mailing list, which includes all the core committers, who be able
to help assess the impact of issues, figure out a resolution, and help
co-ordinate the release of patches to mitigate or fix the problem across all
platforms on which Perl is supported. Please only use this address for
security issues in the Perl core, not for modules independently distributed on
CPAN.
SEE ALSO¶
The
Changes file for an explanation of how to view 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.