perl5110delta
(1)
Name
perl5110delta - what is new for perl v5.11.0
Synopsis
Please see following description for synopsis
Description
Perl Programmers Reference Guide PERL5110DELTA(1)
NAME
perl5110delta - what is new for perl v5.11.0
DESCRIPTION
This document describes differences between the 5.10.0
release and the 5.11.0 development release.
Incompatible Changes
Unicode interpretation of \w, \d, \s, and the POSIX character
classes redefined.
Previous versions of Perl tried to map POSIX style character
class definitions onto Unicode property names so that
patterns would "dwim" when matches were made against latin-1
or unicode strings. This proved to be a mistake, breaking
character class negation, causing forward compatibility
problems (as Unicode keeps updating their property
definitions and adding new characters), and other problems.
Therefore we have now defined a new set of artificial
"unicode" property names which will be used to do unicode
matching of patterns using POSIX style character classes and
perl short-form escape character classes like \w and \d.
The key change here is that \d will no longer match every
digit in the unicode standard (there are thousands) nor will
\w match every word character in the standard, instead they
will match precisely their POSIX or Perl definition.
Those needing to match based on Unicode properties can
continue to do so by using the \p{} syntax to match
whichever property they like, including the new artificial
definitions.
NOTE: This is a backwards incompatible no-warning change in
behaviour. If you are upgrading and you process large
volumes of text look for POSIX and Perl style character
classes and change them to the relevent property name (by
removing the word 'Posix' from the current name).
The following table maps the POSIX character class names,
the escapes and the old and new Unicode property mappings:
POSIX Esc Class New-Property ! Old-Property
----------------------------------------------+-------------
alnum [0-9A-Za-z] IsPosixAlnum ! IsAlnum
alpha [A-Za-z] IsPosixAlpha ! IsAlpha
ascii [\000-\177] IsASCII = IsASCII
blank [\011 ] IsPosixBlank !
cntrl [\0-\37\177] IsPosixCntrl ! IsCntrl
digit \d [0-9] IsPosixDigit ! IsDigit
graph [!-~] IsPosixGraph ! IsGraph
lower [a-z] IsPosixLower ! IsLower
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print [ -~] IsPosixPrint ! IsPrint
punct [!-/:-@[-`{-~] IsPosixPunct ! IsPunct
space [\11-\15 ] IsPosixSpace ! IsSpace
\s [\11\12\14\15 ] IsPerlSpace ! IsSpacePerl
upper [A-Z] IsPosixUpper ! IsUpper
word \w [0-9A-Z_a-z] IsPerlWord ! IsWord
xdigit [0-9A-Fa-f] IsXDigit = IsXDigit
If you wish to build perl with the old mapping you may do so
by setting
#define PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS 1
in regcomp.h, and then setting
PERL_TEST_LEGACY_POSIX_CC
to true your enviornment when testing.
@INC reorganization
In @INC, ARCHLIB and PRIVLIB now occur after after the
current version's site_perl and vendor_perl.
Switch statement changes
The handling of complex expressions by the "given"/"when"
switch statement has been enhanced. These enhancements are
also available in 5.10.1 and subsequent 5.10 releases. 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,
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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. These changers were also made
for the 5.10.1 release, and will remain in subsequent 5.10
releases.
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:
o 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).
o "%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.
o 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.
o "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).
o "$scalar ~~ @array" now always distributes the smart
match across the elements of the array. It's true if one
element in @array verifies "$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
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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.)
Labels can't be keywords
Labels used as targets for the "goto", "last", "next" or
"redo" statements cannot be keywords anymore. This
restriction will prevent potential confusion between the
"goto LABEL" and "goto EXPR" syntaxes: for example, a
statement like "goto print" would jump to a label whose name
would be the return value of "print()", (usually 1), instead
of a label named "print". Moreover, the other control flow
statements would just ignore any keyword passed to them as a
label name. Since such labels cannot be defined anymore,
this kind of error will be avoided.
Other incompatible changes
o The semantics of "use feature :5.10*" have changed
slightly. See "Modules and Pragmata" for more
information.
o 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.)
o 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.
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o 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, nearly all dual-
life 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.
o 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.
o As part of the "ExtUtils::MakeMaker" upgrade, the
"ExtUtils::MakeMaker::bytes" and
"ExtUtils::MakeMaker::vmsish" modules have been removed
from this distribution.
o "Module::CoreList" no longer contains the %:patchlevel
hash.
o 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;
o "length undef" now returns undef.
o Unsupported private C API functions are now declared
"static" to prevent leakage to Perl's public API.
o To support the bootstrapping process, miniperl no longer
builds with UTF-8 support in the regexp engine.
This allows a build to complete with PERL_UNICODE set
and a UTF-8 locale. Without this there's a
bootstrapping problem, as miniperl can't load the UTF-8
components of the regexp engine, because they're not yet
built.
o miniperl's @INC is now restricted to just -I..., the
split of $ENV{PERL5LIB}, and "."
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o A space or a newline is now required after a "#line XXX"
directive.
o Tied filehandles now have an additional method EOF which
provides the EOF type
o To better match all other flow control statements,
"foreach" may no longer be used as an attribute.
Core Enhancements
Unicode Character Database 5.1.0
The copy of the Unicode Character Database included in Perl
5.11.0 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 5.11.0 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)
"\N" regex escape
A new regex escape has been added, "\N". It will match any
character that is not a newline, independently from the
presence or absence of the single line match modifier "/s".
(If "\N" is followed by an opening brace and by a letter,
perl will still assume that a Unicode character name is
coming, so compatibility is preserved.) (Rafael Garcia-
Suarez)
Implicit strictures
Using the "use VERSION" syntax with a version number greater
or equal to 5.11.0 will also lexically enable strictures
just like "use strict" would do (in addition to enabling
features.) So, the following:
use 5.11.0;
will now imply:
use strict;
use feature ':5.11';
Parallel tests
The core distribution can now run its regression tests in
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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.
The "..." operator
A new operator, "...", nicknamed the Yada Yada operator, has
been added. It is intended to mark placeholder code, that
is not yet implemented. See "Yada Yada Operator" in perlop.
(chromatic)
DTrace support
Some support for DTrace has been added. See "DTrace support"
in INSTALL.
Support for "configure_requires" in CPAN module metadata
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.
"each" is now more flexible
The "each" function can now operate on arrays.
Y2038 compliance
Perl's core time-related functions are now Y2038 compliant.
(With 29 years to spare!)
$, flexibility
The variable $, may now be tied.
// in where clauses
// now behaves like || in when clauses
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Enabling warnings from your shell environment
You can now set "-W" from the "PERL5OPT" environment
variable
"delete local"
"delete local" now allows you to locally delete a hash
entry.
New support for Abstract namespace sockets
Abstract namespace sockets are Linux-specific socket type
that live in AF_UNIX family, slightly abusing it to be able
to use arbitrary character arrays as addresses: They start
with nul byte and are not terminated by nul byte, but with
the length passed to the socket() system call.
Modules and Pragmata
Dual-lifed modules moved
Dual-lifed modules maintained primarily in the Perl core now
live in dist/. Dual-lifed modules maintained primarily on
CPAN now live in cpan/
In previous releases of Perl, it was customary to enumerate
all module changes in this section of the "perldelta" file.
From 5.11.0 forward only notable updates (such as new or
deprecated modules ) will be listed in this section. For a
complete reference to the versions of modules shipped in a
given release of perl, please see Module::CoreList.
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
"overloading"
See "The "overloading" pragma" above.
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"attrs"
The "attrs" pragma has been removed. It had been marked
as deprecated since 5.6.0.
"charnames"
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}".
"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.
"mro"
Upgraded from version 1.00 to 1.01. Performance for
single inheritance is 40% faster - see "Performance
Enhancements" below.
"mro" is now implemented as an XS extension. The
documented interface has not changed. Code relying on
the implementation detail that some "mro::" methods
happened to be available at all times gets to "keep both
pieces".
Updated Modules
"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.
"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.
"UNIVERSAL"
Upgraded from version 1.04 to 1.05.
"UNIVERSAL->import()" is now deprecated.
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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.
perlbug
perlbug now uses %Module::CoreList::bug_tracker to print
out upstream bug tracker URLs.
Where the user names a module that their bug report is
about, and we know the URL for its upstream bug tracker,
provide a message to the user explaining that the core
copies the CPAN version directly, and provide the URL
for reporting the bug directly to upstream.
perlthanks
Perl 5.11.0 added 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
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This describes how to access the perl source using the
git version control system.
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.
o Documented -X overloading.
o Documented that "when()" treats specially most of the
filetest operators
o Documented when as a syntax modifier
o Eliminated "Old Perl threads tutorial", which describes
5005 threads.
pod/perlthrtut.pod is the same material reworked for
ithreads.
o Correct previous documentation: v-strings are not
deprecated
With version objects, we need them to use MODULE VERSION
syntax. This patch removes the deprecation note.
o Added security contact information to perlsec
Performance Enhancements
o A new internal cache means that "isa()" will often be
faster.
o The implementation of "C3" Method Resolution Order has
been optimised - linearisation for classes with single
inheritance is 40% faster. Performance for multiple
inheritance is unchanged.
o 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
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"sort keys %hash" in the scope of "use locale" much
faster.
o Empty "DESTROY" methods are no longer called.
o Faster "Perl_sv_utf8_upgrade()"
o Speed up "keys" on empty hash
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. "Safe" has been split out
from being part of "Opcode", and "mro" is now an extension
in its own right.
Nearly all dual-life modules have been moved from lib to
ext, and will now appear as known "nonxs_ext". This will
made no difference to the structure of an installed perl,
nor will the modules installed differ, unless you run
Configure with options to specify an exact list of
extensions to build. In this case, you will rapidly become
aware that you need to add to your list, because various
modules needed to complete the build, such as
"ExtUtils::ParseXS", have now become extensions, and without
them the build will fail well before it attempts to run the
regression tests.
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
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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.
Platform Specific Changes
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.
DomainOS
Support for Apollo DomainOS was removed in Perl 5.11.0
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.
MachTen
Support for Tenon Intersystems MachTen Unix layer for
MacOS Classic was removed in Perl 5.11.0
MiNT
Support for Atari MiNT was removed in Perl 5.11.0.
MirOS BSD
Perl should now build on MirOS BSD.
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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.
"File::Copy" now detects Unix compatibility mode on VMS.
Selected Bug Fixes
o "-I" on shebang line now adds directories in front of
@INC as documented, and as does "-I" when specified on
the command-line.
o "kill" is now fatal when called on non-numeric process
identifiers. Previously, an 'undef' process identifier
would be interpreted as a request to kill process "0",
which would terminate the current process group on POSIX
systems. Since process identifiers are always integers,
killing a non-numeric process is now fatal.
o 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.
o Fixed memory leak on "while (1) { map 1, 1 }" [RT
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#53038].
o Some potential coredumps in PerlIO fixed [RT
#57322,54828].
o The debugger now works with lvalue subroutines.
o The debugger's "m" command was broken on modules that
defined constants [RT #61222].
o "crypt" and string complement could return tainted
values for untainted arguments [RT #59998].
o 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].
o On some Unix systems, the value in $? would not have the
top bit set ("$? & 128") even if the child core dumped.
o Under some circumstances, $^R could incorrectly become
undefined [RT #57042].
o In the XS API, various hash functions, when passed a
pre-computed hash where the key is UTF-8, might result
in an incorrect lookup.
o XS code including XSUB.h before perl.h gave a compile-
time error [RT #57176].
o "$object->isa('Foo')" would report false if the package
"Foo" didn't exist, even if the object's @ISA contained
"Foo".
o Various bugs in the new-to 5.10.0 mro code, triggered by
manipulating @ISA, have been found and fixed.
o Bitwise operations on references could crash the
interpreter, e.g. "$x=\$y; $x |= "foo"" [RT #54956].
o 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
o 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
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greater than 255 [RT #59908].
o "B::Deparse" failed to correctly deparse various
constructs: "readpipe STRING" [RT #62428],
"CORE::require(STRING)" [RT #62488], "sub foo(_)" [RT
#62484].
o Using "setpgrp" with no arguments could corrupt the perl
stack.
o The block form of "eval" is now specifically trappable
by "Safe" and "ops". Previously it was erroneously
treated like string "eval".
o In 5.10.0, the two characters "[~" were sometimes parsed
as the smart match operator ("~~") [RT #63854].
o 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)*$/
o "shmget" was limited to a 32 bit segment size on a 64
bit OS [RT #63924].
o 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
o On Windows, '.\foo' and '..\foo' were treated
differently than './foo' and '../foo' by "do" and
"require" [RT #63492].
o Assigning a format to a glob could corrupt the format;
e.g.:
*bar=*foo{FORMAT}; # foo format now bad
o 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 $type".
o Under "use filetest 'access'", "-x" was using the wrong
access mode. This has been fixed [RT #49003].
o "length" on a tied scalar that returned a Unicode value
would not be correct the first time. This has been
fixed.
o Using an array "tie" inside in array "tie" could SEGV.
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This has been fixed. [RT #51636]
o A race condition inside "PerlIOStdio_close()" has been
identified and fixed. This used to cause various
threading issues, including SEGVs.
o In "unpack", the use of "()" groups in scalar context
was internally placing a list on the interpreter's
stack, which manifested in various ways, including
SEGVs. This is now fixed [RT #50256].
o Magic was called twice in "substr", "\&$x", "tie $x, $m"
and "chop". These have all been fixed.
o 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].
o The line numbers for warnings inside "elsif" are now
correct.
o The ".." operator now works correctly with ranges whose
ends are at or close to the values of the smallest and
largest integers.
o "binmode STDIN, ':raw'" could lead to segmentation
faults on some platforms. This has been fixed [RT
#54828].
o An off-by-one error meant that "index $str, ..." was
effectively being executed as "index "$str\0", ...".
This has been fixed [RT #53746].
o Various leaks associated with named captures in regexes
have been fixed [RT #57024].
o A weak reference to a hash would leak. This was
affecting "DBI" [RT #56908].
o Using (?|) in a regex could cause a segfault [RT
#59734].
o Use of a UTF-8 "tr//" within a closure could cause a
segfault [RT #61520].
o Calling "Perl_sv_chop()" or otherwise upgrading an SV
could result in an unaligned 64-bit access on the SPARC
architecture [RT #60574].
o In the 5.10.0 release, "inc_version_list" would
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incorrectly list "5.10.*" after "5.8.*"; this affected
the @INC search order [RT #67628].
o In 5.10.0, "pack "a*", $tainted_value" returned a non-
tainted value [RT #52552].
o 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].
o In the 5.10.0 release, a dynamically created "AUTOLOAD"
method might be missed (method cache issue) [RT
#60220,60232].
o In the 5.10.0 release, a combination of "use feature"
and "//ee" could cause a memory leak [RT #63110].
o "-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].
o 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
o Previously missing files from Unicode 5.1 Character
Database are now included.
o "TMPDIR" is now honored when opening an anonymous
temporary file
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"
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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
o TODO: "SVt_RV" is gone. RVs are now stored in IVs
o TODO: REGEXPs are first class
o TODO: OOK is reworked, such that an OOKed scalar is PV
not PVIV
o 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.
o "Perl_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.
o New macros "dSAVEDERRNO", "dSAVE_ERRNO", "SAVE_ERRNO",
"RESTORE_ERRNO" have been added to formalise the
temporary saving of the "errno" variable.
o The function "Perl_sv_insert_flags" has been added to
augment "Perl_sv_insert".
o The function "Perl_newSV_type(type)" has been added,
equivalent to "Perl_newSV()" followed by
"Perl_sv_upgrade(type)".
o 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 "Perl_sv_2mortal()" on the new SV.
There is also a wrapper that takes constant strings,
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"newSVpvs_flags()".
o The function "Perl_croak_xs_usage" has been added as a
wrapper to "Perl_croak".
o The functions "PerlIO_find_layer" and
"PerlIO_list_alloc" are now exported.
o "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.
o "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.
o 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.
o "Perl_mg_magical()" would sometimes incorrectly turn on
"SvRMAGICAL()". This has been fixed.
o 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.
o 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.
o Smartmatch resolution tracing has been added as a new
diagnostic. Use "-DM" to enable it.
o A new debugging flag "-DB" now dumps subroutine
definitions, leaving "-Dx" for its original purpose of
dumping syntax trees.
o 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.
o 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
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of "const" correctness in the core, and helped picked up
some errors (now fixed).
o Macros "mPUSHs()" and "mXPUSHs()" have been added, for
pushing SVs on the stack and mortalizing them.
o Use of the private structure "mro_meta" has changed
slightly. Nothing outside the core should be accessing
this directly anyway.
o 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".
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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
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regressions from either 5.10.0 or 5.8.x.
o "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
o 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/;
o 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.
o "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.
o The following modules will be removed from the core
distribution in a future release, and should be
installed from CPAN instead. Distributions on CPAN which
require these should add them to their prerequisites.
The core versions of these modules warnings will issue a
deprecation warning.
o "Class::ISA"
o "Pod::Plainer"
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o "Shell"
Currently support to install from CPAN without a force
is "TODO" in CPAN and CPANPLUS. This will be addressed
before 5.12.0 ships.
o "suidperl" has been removed. It used to provide a
mechanism to emulate setuid permission bits on systems
that don't support it properly.
o Deprecate assignment to $[
o Remove attrs, which has been deprecated since
1999/10/02.
o Deprecate use of the attribute :locked on subroutines.
o Deprecate using "locked" with the attributes pragma.
o Deprecate using "unique" with the attributes pragma.
o warn if ++ or -- are unable to change the value because
it's beyond the limit of representation
This uses a new warnings category: "imprecision".
o Make lc/uc/lcfirst/ucfirst warn when passed undef.
o Show constant in "Useless use of a constant in void
context"
o Make the new warning report undef constants as undef
o Add a new warning, "Prototype after '%s'"
o Tweak the "Illegal character in prototype" warning so
it's more precise when reporting illegal characters
after _
o Unintended interpolation of $\ in regex
o Make overflow warnings in gmtime/localtime only occur
when warnings are on
o Improve mro merging error messages.
They are now very similar to those produced by
Algorithm::C3.
o Amelioration of the error message "Unrecognized
character %s in column %d"
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Changes the error message to "Unrecognized character %s;
marked by <-- HERE after %s<-- HERE near column %d".
This should make it a little simpler to spot and correct
the suspicious character.
o Explicitely point to $. when it causes an uninitialized
warning for ranges in scalar context
o Deprecated numerous Perl 4-era libraries:
termcap.pl, tainted.pl, stat.pl, shellwords.pl, pwd.pl,
open3.pl, open2.pl, newgetopt.pl, look.pl, find.pl,
finddepth.pl, importenv.pl, hostname.pl, getopts.pl,
getopt.pl, getcwd.pl, flush.pl, fastcwd.pl,
exceptions.pl, ctime.pl, complete.pl, cacheout.pl,
bigrat.pl, bigint.pl, bigfloat.pl, assert.pl, abbrev.pl,
dotsh.pl, and timelocal.pl are all now deprecated. Using
them will incur a warning.
Acknowledgements
Some of the work in this release was funded by a TPF grant
funded by Dijkmat BV, The Netherlands.
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.
Much of the work of categorizing changes in this perldelta
file was contributed by the following porters using
changelogger.bestpractical.com:
Nicholas Clark, leon, shawn, alexm, rjbs, rafl, Pedro Melo,
brunorc, anonymous, X, Tom Hukins, anonymous, Jesse,
dagolden, Moritz Onken, Mark Fowler, chorny, anonymous, tmtm
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.
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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.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | runtime/perl-512 |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
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.
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.cpan.org/src/5.0/perl-5.12.5.tar.bz2
Further information about this software can be found on the
open source community website at http://www.perl.org/.
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