PERL5110DELTA(1) Perl Programmers Reference Guide PERL5110DELTA(1)NAMEperl5110delta - 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 relevant
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
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 environment 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, 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:
· 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.)
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
· 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, 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.
· 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;
· "length undef" now returns undef.
· Unsupported private C API functions are now declared "static" to
prevent leakage to Perl's public API.
· 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.
· miniperl's @INC is now restricted to just -I..., the split of
$ENV{PERL5LIB}, and "."
· A space or a newline is now required after a "#line XXX" directive.
· Tied filehandles now have an additional method EOF which provides
the EOF type
· 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 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
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.
"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.
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
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.
· Documented -X overloading.
· Documented that "when()" treats specially most of the filetest
operators
· Documented when as a syntax modifier
· Eliminated "Old Perl threads tutorial", which describes 5005
threads.
pod/perlthrtut.pod is the same material reworked for ithreads.
· 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.
· Added security contact information to perlsec
Performance Enhancements
· A new internal cache means that "isa()" will often be faster.
· 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.
· 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.
· Faster "Perl_sv_utf8_upgrade()"
· 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 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.
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
· "-I" on shebang line now adds directories in front of @INC as
documented, and as does "-I" when specified on the command-line.
· "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.
· 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, $^R could incorrectly become undefined
[RT #57042].
· In the XS API, various hash functions, when passed a pre-computed
hash where the key is UTF-8, might result in an incorrect lookup.
· XS code including XSUB.h before perl.h gave a compile-time error
[RT #57176].
· "$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 "Perl_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
· Previously missing files from Unicode 5.1 Character Database are
now included.
· "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"
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
· TODO: "SVt_RV" is gone. RVs are now stored in IVs
· TODO: REGEXPs are first class
· TODO: OOK is reworked, such that an OOKed scalar is PV not PVIV
· 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.
· "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.
· 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 "Perl_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.
· Smartmatch resolution tracing has been added as a new diagnostic.
Use "-DM" to enable it.
· A new debugging flag "-DB" now dumps subroutine definitions,
leaving "-Dx" for its original purpose of dumping syntax trees.
· 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.
· 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.
· "Class::ISA"
· "Pod::Plainer"
· "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.
· "suidperl" has been removed. It used to provide a mechanism to
emulate setuid permission bits on systems that don't support it
properly.
· Deprecate assignment to $[
· Remove attrs, which has been deprecated since 1999/10/02.
· Deprecate use of the attribute :locked on subroutines.
· Deprecate using "locked" with the attributes pragma.
· Deprecate using "unique" with the attributes pragma.
· warn if ++ or -- are unable to change the value because it's beyond
the limit of representation
This uses a new warnings category: "imprecision".
· Make lc/uc/lcfirst/ucfirst warn when passed undef.
· Show constant in "Useless use of a constant in void context"
· Make the new warning report undef constants as undef
· Add a new warning, "Prototype after '%s'"
· Tweak the "Illegal character in prototype" warning so it's more
precise when reporting illegal characters after _
· Unintended interpolation of $\ in regex
· Make overflow warnings in gmtime/localtime only occur when warnings
are on
· Improve mro merging error messages.
They are now very similar to those produced by Algorithm::C3.
· Amelioration of the error message "Unrecognized character %s in
column %d"
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.
· Explicitly point to $. when it causes an uninitialized warning for
ranges in scalar context
· 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.
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.
perl v5.14.4 2012-12-19 PERL5110DELTA(1)
