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perl5120delta - what is new for perl v5.12.0

DESCRIPTION

This document describes differences between the 5.10.0 release and the 5.12.0 release.

Many of the bug fixes in 5.12.0 are already included in the 5.10.1 maintenance release.

You can see the list of those changes in the 5.10.1 release notes (perl5101delta).

Core Enhancements

New "package NAME VERSION" syntax
This new syntax allows a module author to set the $VERSION of a namespace when the
namespace is declared with 'package'. It eliminates the need for "our $VERSION = ..." and
similar constructs. E.g.

package Foo::Bar 1.23;
# $Foo::Bar::VERSION == 1.23

There are several advantages to this:

· $VERSION is parsed in exactly the same way as "use NAME VERSION"

· $VERSION is set at compile time

· $VERSION is a version object that provides proper overloading of comparison operators
so comparing $VERSION to decimal (1.23) or dotted-decimal (v1.2.3) version numbers
works correctly.

· Eliminates "$VERSION = ..." and "eval $VERSION" clutter

· As it requires VERSION to be a numeric literal or v-string literal, it can be
statically parsed by toolchain modules without "eval" the way MM->parse_version does
for "$VERSION = ..."

It does not break old code with only "package NAME", but code that uses "package NAME
VERSION" will need to be restricted to perl 5.12.0 or newer This is analogous to the
change to "open" from two-args to three-args. Users requiring the latest Perl will
benefit, and perhaps after several years, it will become a standard practice.

However, "package NAME VERSION" requires a new, 'strict' version number format. See
"Version number formats" for details.

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.

Implicit strictures
Using the "use VERSION" syntax with a version number greater or equal to 5.11.0 will
lexically enable strictures just like "use strict" would do (in addition to enabling
features.) The following:

use 5.12.0;

means:

use strict;
use feature ':5.12';

Unicode improvements
Perl 5.12 comes with Unicode 5.2, the latest version available to us at the time of
release. This version of Unicode was released in October 2009. See
<http://www.unicode.org/versions/Unicode5.2.0> for further details about what's changed in
this version of the standard. See perlunicode for instructions on installing and using
other versions of Unicode.

Additionally, Perl's developers have significantly improved Perl's Unicode implementation.
For full details, see "Unicode overhaul" below.

Y2038 compliance
Perl's core time-related functions are now Y2038 compliant. (It may not mean much to you,
but your kids will love it!)

qr overloading
It is now possible to overload the "qr//" operator, that is, conversion to regexp, like it
was already possible to overload conversion to boolean, string or number of objects. It is
invoked when an object appears on the right hand side of the "=~" operator or when it is
interpolated into a regexp. See overload.

Pluggable keywords
Extension modules can now cleanly hook into the Perl parser to define new kinds of
keyword-headed expression and compound statement. The syntax following the keyword is
defined entirely by the extension. This allows a completely non-Perl sublanguage to be
parsed inline, with the correct ops cleanly generated.

See "PL_keyword_plugin" in perlapi for the mechanism. The Perl core source distribution
also includes a new module XS::APItest::KeywordRPN, which implements reverse Polish
notation arithmetic via pluggable keywords. This module is mainly used for test purposes,
and is not normally installed, but also serves as an example of how to use the new
mechanism.

Perl's developers consider this feature to be experimental. We may remove it or change it
in a backwards-incompatible way in Perl 5.14.

APIs for more internals
The lowest layers of the lexer and parts of the pad system now have C APIs available to XS
extensions. These are necessary to support proper use of pluggable keywords, but have
other uses too. The new APIs are experimental, and only cover a small proportion of what
would be necessary to take full advantage of the core's facilities in these areas. It is
intended that the Perl 5.13 development cycle will see the addition of a full range of
clean, supported interfaces.

Perl's developers consider this feature to be experimental. We may remove it or change it
in a backwards-incompatible way in Perl 5.14.

Overridable function lookup
Where an extension module hooks the creation of rv2cv ops to modify the subroutine lookup
process, this now works correctly for bareword subroutine calls. This means that
prototypes on subroutines referenced this way will be processed correctly. (Previously
bareword subroutine names were initially looked up, for parsing purposes, by an unhookable
mechanism, so extensions could only properly influence subroutine names that appeared with
an "&" sigil.)

A proper interface for pluggable Method Resolution Orders
As of Perl 5.12.0 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.

"\N" experimental regex escape
Perl now supports "\N", a new regex escape which you can think of as the inverse of "\n".
It will match any character that is not a newline, independently from the presence or
absence of the single line match modifier "/s". It is not usable within a character class.
"\N{3}" means to match 3 non-newlines; "\N{5,}" means to match at least 5. "\N{NAME}"
still means the character or sequence named "NAME", but "NAME" no longer can be things
like 3, or "5,".

This will break a custom charnames translator which allows numbers for character names, as
"\N{3}" will now mean to match 3 non-newline characters, and not the character whose name
is 3. (No name defined by the Unicode standard is a number, so only custom translators
might be affected.)

Perl's developers are somewhat concerned about possible user confusion with the existing
"\N{...}" construct which matches characters by their Unicode name. Consequently, this
feature is experimental. We may remove it or change it in a backwards-incompatible way in
Perl 5.14.

DTrace support
Perl now has some support for DTrace. 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", "keys", "values" are now more flexible
The "each", "keys", "values" function can now operate on arrays.

"when" as a statement modifier
"when" is now allowed to be used as a statement modifier.

$, flexibility
The variable $, may now be tied.

// in when 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.

32-bit limit on substr arguments removed
The 32-bit limit on "substr" arguments has now been removed. The full range of the
system's signed and unsigned integers is now available for the "pos" and "len" arguments.

Potentially Incompatible Changes

Deprecations warn by default
Over the years, Perl's developers have deprecated a number of language features for a
variety of reasons. Perl now defaults to issuing a warning if a deprecated language
feature is used. Many of the deprecations Perl now warns you about have been deprecated
for many years. You can find a list of what was deprecated in a given release of Perl in
the "perl5xxdelta.pod" file for that release.

To disable this feature in a given lexical scope, you should use "no warnings
'deprecated';" For information about which language features are deprecated and
explanations of various deprecation warnings, please see perldiag. See "Deprecations"
below for the list of features and modules Perl's developers have deprecated as part of
this release.

Version number formats
Acceptable version number formats have been formalized into "strict" and "lax" rules.
"package NAME VERSION" takes a strict version number. "UNIVERSAL::VERSION" and the
version object constructors take lax version numbers. Providing an invalid version will
result in a fatal error. The version argument in "use NAME VERSION" is first parsed as a
numeric literal or v-string and then passed to "UNIVERSAL::VERSION" (and must then pass
the "lax" format test).

These formats are documented fully in the version module. To a first approximation, a
"strict" version number is a positive decimal number (integer or decimal-fraction) without
exponentiation or else a dotted-decimal v-string with a leading 'v' character and at least
three components. A "lax" version number allows v-strings with fewer than three components
or without a leading 'v'. Under "lax" rules, both decimal and dotted-decimal versions may
have a trailing "alpha" component separated by an underscore character after a fractional
or dotted-decimal component.

The version module adds "version::is_strict" and "version::is_lax" functions to check a
scalar against these rules.

@INC reorganization
In @INC, "ARCHLIB" and "PRIVLIB" now occur after the current version's "site_perl" and
"vendor_perl". Modules installed into "site_perl" and "vendor_perl" will now be loaded in
preference to those installed in "ARCHLIB" and "PRIVLIB".

REGEXPs are now first class
Internally, Perl now treats compiled regular expressions (such as those created with
"qr//") as first class entities. Perl modules which serialize, deserialize or otherwise
have deep interaction with Perl's internal data structures need to be updated for this
change. Most affected CPAN modules have already been updated as of this writing.

Switch statement changes
The "given"/"when" switch statement handles complex statements better than Perl 5.10.0 did
(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)".)

Smart match changes
Since Perl 5.10.0, Perl's developers have made a number of changes to the smart match
operator. These, of course, also alter the behaviour of the switch statements where smart
matching is implicitly used. These changes were also made for the 5.10.1 release, and
will remain in subsequent 5.10 releases.

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 potentially incompatible changes
· The definitions of a number of Unicode properties have changed to match those of the
current Unicode standard. These are listed above under "Unicode overhaul". This change
may break code that expects the old definitions.

· The boolkeys op has moved to the group of hash ops. This breaks binary compatibility.

· Filehandles are now always blessed into "IO::File".

The previous behaviour was to bless Filehandles into FileHandle (an empty proxy class)
if it was loaded into memory and otherwise to bless them into "IO::Handle".

· The semantics of "use feature :5.10*" have changed slightly. See "Modules and
Pragmata" for more information.

· Perl's developers now use git, rather than Perforce. This should be a purely internal
change only relevant to people actively working on the core. However, you may see
minor difference in perl as a consequence of the change. For example in some of
details of the output of "perl -V". See perlrepository for more information.

· As part of the "Test::Harness" 2.x to 3.x upgrade, the experimental
"Test::Harness::Straps" module has been removed. See "Modules and Pragmata" 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.

· "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.

· Perl's command-line switch "-P", which was deprecated in version 5.10.0, has now been
removed. The CPAN module "Filter::cpp" can be used as an alternative.

Deprecations

From time to time, Perl's developers find it necessary to deprecate features or modules
we've previously shipped as part of the core distribution. We are well aware of the pain
and frustration that a backwards-incompatible change to Perl can cause for developers
building or maintaining software in Perl. You can be sure that when we deprecate a
functionality or syntax, it isn't a choice we make lightly. Sometimes, we choose to
deprecate functionality or syntax because it was found to be poorly designed or
implemented. Sometimes, this is because they're holding back other features or causing
performance problems. Sometimes, the reasons are more complex. Wherever possible, we try
to keep deprecated functionality available to developers in its previous form for at least
one major release. So long as a deprecated feature isn't actively disrupting our ability
to maintain and extend Perl, we'll try to leave it in place as long as possible.

The following items are now deprecated:

suidperl
"suidperl" is no longer part of Perl. It used to provide a mechanism to emulate setuid
permission bits on systems that don't support it properly.

Use of ":=" to mean an empty attribute list
An accident of Perl's parser meant that these constructions were all equivalent:

my $pi := 4;
my $pi : = 4;
my $pi : = 4;

with the ":" being treated as the start of an attribute list, which ends before the
"=". As whitespace is not significant here, all are parsed as an empty attribute list,
hence all the above are equivalent to, and better written as

my $pi = 4;

because no attribute processing is done for an empty list.

As is, this meant that ":=" cannot be used as a new token, without silently changing
the meaning of existing code. Hence that particular form is now deprecated, and will
become a syntax error. If it is absolutely necessary to have empty attribute lists
(for example, because of a code generator) then avoid the warning by adding a space
before the "=".

"UNIVERSAL->import()"
The method "UNIVERSAL->import()" is now deprecated. Attempting to pass import
arguments to a "use UNIVERSAL" statement will result in a deprecation warning.

Use of "goto" to jump into a construct
Using "goto" to jump from an outer scope into an inner scope is now deprecated. This
rare use case was causing problems in the implementation of scopes.

Custom character names in \N{name} that don't look like names
In "\N{name}", name can be just about anything. The standard Unicode names have a very
limited domain, but a custom name translator could create names that are, for example,
made up entirely of punctuation symbols. It is now deprecated to make names that don't
begin with an alphabetic character, and aren't alphanumeric or contain other than a
very few other characters, namely spaces, dashes, parentheses and colons. Because of
the added meaning of "\N" (See ""\N" experimental regex escape"), names that look like
curly brace -enclosed quantifiers won't work. For example, "\N{3,4}" now means to
match 3 to 4 non-newlines; before a custom name "3,4" could have been created.

Deprecated Modules
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.

If you ship a packaged version of Perl, either alone or as part of a larger system,
then you should carefully consider the repercussions of core module deprecations. You
may want to consider shipping your default build of Perl with packages for some or all
deprecated modules which install into "vendor" or "site" perl library directories.
This will inhibit the deprecation warnings.

Alternatively, you may want to consider patching lib/deprecate.pm to provide
deprecation warnings specific to your packaging system or distribution of Perl,
consistent with how your packaging system or distribution manages a staged transition
from a release where the installation of a single package provides the given
functionality, to a later release where the system administrator needs to know to
install multiple packages to get that same functionality.

You can silence these deprecation warnings by installing the modules in question from
CPAN. To install the latest version of all of them, just install
"Task::Deprecations::5_12".

Class::ISA
Pod::Plainer
Shell
Switch
Switch is buggy and should be avoided. You may find Perl's new "given"/"when"
feature a suitable replacement. See "Switch statements" in perlsyn for more
information.

Assignment to $[
Use of the attribute :locked on subroutines
Use of "locked" with the attributes pragma
Use of "unique" with the attributes pragma
Perl_pmflag
"Perl_pmflag" is no longer part of Perl's public API. Calling it now generates a
deprecation warning, and it will be removed in a future release. Although listed as
part of the API, it was never documented, and only ever used in toke.c, and prior to
5.10, regcomp.c. In core, it has been replaced by a static function.

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. Earlier, Perl's developers intended to remove
these libraries from Perl's core for the 5.14.0 release.

During final testing before the release of 5.12.0, several developers discovered
current production code using these ancient libraries, some inside the Perl core
itself. Accordingly, the pumpking granted them a stay of execution. They will begin
to warn about their deprecation in the 5.14.0 release and will be removed in the
5.16.0 release.

Unicode overhaul

Perl's developers have made a concerted effort to update Perl to be in sync with the
latest Unicode standard. Changes for this include:

Perl can now handle every Unicode character property. New documentation, perluniprops,
lists all available non-Unihan character properties. By default, perl does not expose
Unihan, deprecated or Unicode-internal properties. See below for more details on these;
there is also a section in the pod listing them, and explaining why they are not exposed.

Perl now fully supports the Unicode compound-style of using "=" and ":" in writing regular
expressions: "\p{property=value}" and "\p{property:value}" (both of which mean the same
thing).

Perl now fully supports the Unicode loose matching rules for text between the braces in
"\p{...}" constructs. In addition, Perl allows underscores between digits of numbers.

Perl now accepts all the Unicode-defined synonyms for properties and property values.

"qr/\X/", which matches a Unicode logical character, has been expanded to work better with
various Asian languages. It now is defined as an extended grapheme cluster. (See
<http://www.unicode.org/reports/tr29/>). Anything matched previously and that made sense
will continue to be accepted. Additionally:

· "\X" will not break apart a "CR LF" sequence.

· "\X" will now match a sequence which includes the "ZWJ" and "ZWNJ" characters.

· "\X" will now always match at least one character, including an initial mark. Marks
generally come after a base character, but it is possible in Unicode to have them in
isolation, and "\X" will now handle that case, for example at the beginning of a line,
or after a "ZWSP". And this is the part where "\X" doesn't match the things that it
used to that don't make sense. Formerly, for example, you could have the nonsensical
case of an accented LF.

· "\X" will now match a (Korean) Hangul syllable sequence, and the Thai and Lao
exception cases.

Otherwise, this change should be transparent for the non-affected languages.

"\p{...}" matches using the Canonical_Combining_Class property were completely broken in
previous releases of Perl. They should now work correctly.

Before Perl 5.12, the Unicode "Decomposition_Type=Compat" property and a Perl extension
had the same name, which led to neither matching all the correct values (with more than
100 mistakes in one, and several thousand in the other). The Perl extension has now been
renamed to be "Decomposition_Type=Noncanonical" (short: "dt=noncanon"). It has the same
meaning as was previously intended, namely the union of all the non-canonical
Decomposition types, with Unicode "Compat" being just one of those.

"\p{Decomposition_Type=Canonical}" now includes the Hangul syllables.

"\p{Uppercase}" and "\p{Lowercase}" now work as the Unicode standard says they should.
This means they each match a few more characters than they used to.

"\p{Cntrl}" now matches the same characters as "\p{Control}". This means it no longer will
match Private Use (gc=co), Surrogates (gc=cs), nor Format (gc=cf) code points. The Format
code points represent the biggest possible problem. All but 36 of them are either
officially deprecated or strongly discouraged from being used. Of those 36, likely the
most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ, WJ, and similar
characters, plus bidirectional controls.

"\p{Alpha}" now matches the same characters as "\p{Alphabetic}". Before 5.12, Perl's
definition included a number of things that aren't really alpha (all marks) while omitting
many that were. The definitions of "\p{Alnum}" and "\p{Word}" depend on Alpha's definition
and have changed accordingly.

"\p{Word}" no longer incorrectly matches non-word characters such as fractions.

"\p{Print}" no longer matches the line control characters: Tab, LF, CR, FF, VT, and NEL.
This brings it in line with standards and the documentation.

"\p{XDigit}" now matches the same characters as "\p{Hex_Digit}". This means that in
addition to the characters it currently matches, "[A-Fa-f0-9]", it will also match the 22
fullwidth equivalents, for example U+FF10: FULLWIDTH DIGIT ZERO.

The Numeric type property has been extended to include the Unihan characters.

There is a new Perl extension, the 'Present_In', or simply 'In', property. This is an
extension of the Unicode Age property, but "\p{In=5.0}" matches any code point whose usage
has been determined as of Unicode version 5.0. The "\p{Age=5.0}" only matches code points
added in precisely version 5.0.

A number of properties now have the correct values for unassigned code points. The
affected properties are Bidi_Class, East_Asian_Width, Joining_Type, Decomposition_Type,
Hangul_Syllable_Type, Numeric_Type, and Line_Break.

The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties are now up to date
with current Unicode definitions.

Earlier versions of Perl erroneously exposed certain properties that are supposed to be
Unicode internal-only. Use of these in regular expressions will now generate, if enabled,
a deprecation warning message. The properties are: Other_Alphabetic,
Other_Default_Ignorable_Code_Point, Other_Grapheme_Extend, Other_ID_Continue,
Other_ID_Start, Other_Lowercase, Other_Math, and Other_Uppercase.

It is now possible to change which Unicode properties Perl understands on a per-
installation basis. As mentioned above, certain properties are turned off by default.
These include all the Unihan properties (which should be accessible via the CPAN module
Unicode::Unihan) and any deprecated or Unicode internal-only property that Perl has never
exposed.

The generated files in the "lib/unicore/To" directory are now more clearly marked as being
stable, directly usable by applications. New hash entries in them give the format of the
normal entries, which allows for easier machine parsing. Perl can generate files in this
directory for any property, though most are suppressed. You can find instructions for
changing which are written in perluniprops.

Modules and Pragmata

New Modules and Pragmata
"autodie"
"autodie" 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.

Version 2.06_01 has been added to the Perl core.

"Compress::Raw::Bzip2"
Version 2.024 has been added to the Perl core.

"overloading"
"overloading" allows you to lexically disable or enable overloading for some or all
operations.

Version 0.001 has been added to the Perl core.

"parent"
"parent" establishes an ISA relationship with base classes at compile time. It
provides the key feature of "base" without further unwanted behaviors.

Version 0.223 has been added to the Perl core.

"Parse::CPAN::Meta"
Version 1.40 has been added to the Perl core.

"VMS::DCLsym"
Version 1.03 has been added to the Perl core.

"VMS::Stdio"
Version 2.4 has been added to the Perl core.

"XS::APItest::KeywordRPN"
Version 0.003 has been added to the Perl core.

Updated Pragmata
"base"
Upgraded from version 2.13 to 2.15.

"bignum"
Upgraded from version 0.22 to 0.23.

"charnames"
"charnames" now contains the Unicode NameAliases.txt database file. 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}".

Upgraded from version 1.06 to 1.07.

"constant"
Upgraded from version 1.13 to 1.20.

"diagnostics"
"diagnostics" now supports %.0f formatting internally.

"diagnostics" no longer suppresses "Use of uninitialized value in range (or flip)"
warnings. [perl #71204]

Upgraded from version 1.17 to 1.19.

"feature"
In "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.

"feature" now includes the "unicode_strings" feature:

use feature "unicode_strings";

This pragma turns on Unicode semantics for the case-changing operations ("uc", "lc",
"ucfirst", "lcfirst") on strings that don't have the internal UTF-8 flag set, but that
contain single-byte characters between 128 and 255.

Upgraded from version 1.11 to 1.16.

"less"
"less" now includes the "stash_name" method to allow subclasses of "less" to pick
where in %^H to store their stash.

Upgraded from version 0.02 to 0.03.

"lib"
Upgraded from version 0.5565 to 0.62.

"mro"
"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".

Upgraded from version 1.00 to 1.02.

"overload"
"overload" now allow overloading of 'qr'.

Upgraded from version 1.06 to 1.10.

"threads"
Upgraded from version 1.67 to 1.75.

"threads::shared"
Upgraded from version 1.14 to 1.32.

"version"
"version" now has support for "Version number formats" as described earlier in this
document and in its own documentation.

Upgraded from version 0.74 to 0.82.

"warnings"
"warnings" has a new "warnings::fatal_enabled()" function. It also includes a new
"illegalproto" warning category. See also "New or Changed Diagnostics" for this
change.

Upgraded from version 1.06 to 1.09.

Updated Modules
"Archive::Extract"
Upgraded from version 0.24 to 0.38.

"Archive::Tar"
Upgraded from version 1.38 to 1.54.

"Attribute::Handlers"
Upgraded from version 0.79 to 0.87.

"AutoLoader"
Upgraded from version 5.63 to 5.70.

"B::Concise"
Upgraded from version 0.74 to 0.78.

"B::Debug"
Upgraded from version 1.05 to 1.12.

"B::Deparse"
Upgraded from version 0.83 to 0.96.

"B::Lint"
Upgraded from version 1.09 to 1.11_01.

"CGI"
Upgraded from version 3.29 to 3.48.

"Class::ISA"
Upgraded from version 0.33 to 0.36.

NOTE: "Class::ISA" is deprecated and may be removed from a future version of Perl.

"Compress::Raw::Zlib"
Upgraded from version 2.008 to 2.024.

"CPAN"
Upgraded from version 1.9205 to 1.94_56.

"CPANPLUS"
Upgraded from version 0.84 to 0.90.

"CPANPLUS::Dist::Build"
Upgraded from version 0.06_02 to 0.46.

"Data::Dumper"
Upgraded from version 2.121_14 to 2.125.

"DB_File"
Upgraded from version 1.816_1 to 1.820.

"Devel::PPPort"
Upgraded from version 3.13 to 3.19.

"Digest"
Upgraded from version 1.15 to 1.16.

"Digest::MD5"
Upgraded from version 2.36_01 to 2.39.

"Digest::SHA"
Upgraded from version 5.45 to 5.47.

"Encode"
Upgraded from version 2.23 to 2.39.

"Exporter"
Upgraded from version 5.62 to 5.64_01.

"ExtUtils::CBuilder"
Upgraded from version 0.21 to 0.27.

"ExtUtils::Command"
Upgraded from version 1.13 to 1.16.

"ExtUtils::Constant"
Upgraded from version 0.2 to 0.22.

"ExtUtils::Install"
Upgraded from version 1.44 to 1.55.

"ExtUtils::MakeMaker"
Upgraded from version 6.42 to 6.56.

"ExtUtils::Manifest"
Upgraded from version 1.51_01 to 1.57.

"ExtUtils::ParseXS"
Upgraded from version 2.18_02 to 2.21.

"File::Fetch"
Upgraded from version 0.14 to 0.24.

"File::Path"
Upgraded from version 2.04 to 2.08_01.

"File::Temp"
Upgraded from version 0.18 to 0.22.

"Filter::Simple"
Upgraded from version 0.82 to 0.84.

"Filter::Util::Call"
Upgraded from version 1.07 to 1.08.

"Getopt::Long"
Upgraded from version 2.37 to 2.38.

"IO"
Upgraded from version 1.23_01 to 1.25_02.

"IO::Zlib"
Upgraded from version 1.07 to 1.10.

"IPC::Cmd"
Upgraded from version 0.40_1 to 0.54.

"IPC::SysV"
Upgraded from version 1.05 to 2.01.

"Locale::Maketext"
Upgraded from version 1.12 to 1.14.

"Locale::Maketext::Simple"
Upgraded from version 0.18 to 0.21.

"Log::Message"
Upgraded from version 0.01 to 0.02.

"Log::Message::Simple"
Upgraded from version 0.04 to 0.06.

"Math::BigInt"
Upgraded from version 1.88 to 1.89_01.

"Math::BigInt::FastCalc"
Upgraded from version 0.16 to 0.19.

"Math::BigRat"
Upgraded from version 0.21 to 0.24.

"Math::Complex"
Upgraded from version 1.37 to 1.56.

"Memoize"
Upgraded from version 1.01_02 to 1.01_03.

"MIME::Base64"
Upgraded from version 3.07_01 to 3.08.

"Module::Build"
Upgraded from version 0.2808_01 to 0.3603.

"Module::CoreList"
Upgraded from version 2.12 to 2.29.

"Module::Load"
Upgraded from version 0.12 to 0.16.

"Module::Load::Conditional"
Upgraded from version 0.22 to 0.34.

"Module::Loaded"
Upgraded from version 0.01 to 0.06.

"Module::Pluggable"
Upgraded from version 3.6 to 3.9.

"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 0.36.

"Package::Constants"
Upgraded from version 0.01 to 0.02.

"PerlIO"
Upgraded from version 1.04 to 1.06.

"Pod::Parser"
Upgraded from version 1.35 to 1.37.

"Pod::Perldoc"
Upgraded from version 3.14_02 to 3.15_02.

"Pod::Plainer"
Upgraded from version 0.01 to 1.02.

NOTE: "Pod::Plainer" is deprecated and may be removed from a future version of Perl.

"Pod::Simple"
Upgraded from version 3.05 to 3.13.

"Safe"
Upgraded from version 2.12 to 2.22.

"SelfLoader"
Upgraded from version 1.11 to 1.17.

"Storable"
Upgraded from version 2.18 to 2.22.

"Switch"
Upgraded from version 2.13 to 2.16.

NOTE: "Switch" is deprecated and may be removed from a future version of Perl.

"Sys::Syslog"
Upgraded from version 0.22 to 0.27.

"Term::ANSIColor"
Upgraded from version 1.12 to 2.02.

"Term::UI"
Upgraded from version 0.18 to 0.20.

"Test"
Upgraded from version 1.25 to 1.25_02.

"Test::Harness"
Upgraded from version 2.64 to 3.17.

"Test::Simple"
Upgraded from version 0.72 to 0.94.

"Text::Balanced"
Upgraded from version 2.0.0 to 2.02.

"Text::ParseWords"
Upgraded from version 3.26 to 3.27.

"Text::Soundex"
Upgraded from version 3.03 to 3.03_01.

"Thread::Queue"
Upgraded from version 2.00 to 2.11.

"Thread::Semaphore"
Upgraded from version 2.01 to 2.09.

"Tie::RefHash"
Upgraded from version 1.37 to 1.38.

"Time::HiRes"
Upgraded from version 1.9711 to 1.9719.

"Time::Local"
Upgraded from version 1.18 to 1.1901_01.

"Time::Piece"
Upgraded from version 1.12 to 1.15.

"Unicode::Collate"
Upgraded from version 0.52 to 0.52_01.

"Unicode::Normalize"
Upgraded from version 1.02 to 1.03.

"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.

Removed Modules and Pragmata
"attrs"
Removed from the Perl core. Prior version was 1.02.

"CPAN::API::HOWTO"
Removed from the Perl core. Prior version was 'undef'.

"CPAN::DeferedCode"
Removed from the Perl core. Prior version was 5.50.

"CPANPLUS::inc"
Removed from the Perl core. Prior version was 'undef'.

"DCLsym"
Removed from the Perl core. Prior version was 1.03.

"ExtUtils::MakeMaker::bytes"
Removed from the Perl core. Prior version was 6.42.

"ExtUtils::MakeMaker::vmsish"
Removed from the Perl core. Prior version was 6.42.

"Stdio"
Removed from the Perl core. Prior version was 2.3.

"Test::Harness::Assert"
Removed from the Perl core. Prior version was 0.02.

"Test::Harness::Iterator"
Removed from the Perl core. Prior version was 0.02.

"Test::Harness::Point"
Removed from the Perl core. Prior version was 0.01.

"Test::Harness::Results"
Removed from the Perl core. Prior version was 0.01.

"Test::Harness::Straps"
Removed from the Perl core. Prior version was 0.26_01.

"Test::Harness::Util"
Removed from the Perl core. Prior version was 0.01.

"XSSymSet"
Removed from the Perl core. Prior version was 1.1.

Deprecated Modules and Pragmata
See "Deprecated Modules" above.

Documentation

New Documentation
· perlhaiku contains instructions on how to build perl for the Haiku platform.

· perlmroapi describes the new interface for pluggable Method Resolution Orders.

· perlperf, 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 describes how to access the perl source using the git version control
system.

· perlpolicy extends the "Social contract about contributed modules" into the beginnings
of a document on Perl porting policies.

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.

· 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.

· The syntax "unless (EXPR) BLOCK else BLOCK" is now documented as valid, as is the
syntax "unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK", although actually
using the latter may not be the best idea for the readability of your source code.

· 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 described 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 notice.

· Security contact information is now part of perlsec.

· A significant fraction of the core documentation has been updated to clarify the
behavior of Perl's Unicode handling.

Much of the remaining core documentation has been reviewed and edited for clarity,
consistent use of language, and to fix the spelling of Tom Christiansen's name.

· The Pod specification (perlpodspec) has been updated to bring the specification in
line with modern usage already supported by most Pod systems. A parameter string may
now follow the format name in a "begin/end" region. Links to URIs with a text
description are now allowed. The usage of "L<"section">" has been marked as
deprecated.

· if.pm has been documented in "use" in perlfunc as a means to get conditional loading
of modules despite the implicit BEGIN block around "use".

· The documentation for $1 in perlvar.pod has been clarified.

· "\N{U+code point}" is now documented.

Selected 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.

· "Perl_sv_utf8_upgrade()" is now faster.

· "keys" on empty hash is now faster.

· "if (%foo)" has been optimized to be faster than "if (keys %foo)".

· The string repetition operator ("$str x $num") is now several times faster when $str
has length one or $num is large.

· Reversing an array to itself (as in "@a = reverse @a") in void context now happens in-
place and is several orders of magnitude faster than it used to be. It will also
preserve non-existent elements whenever possible, i.e. for non magical arrays or tied
arrays with "EXISTS" and "DELETE" methods.

Installation and Configuration Improvements

· perlapi, perlintern, perlmodlib and perltoc are now all generated at build time,
rather than being shipped as part of the release.

· 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".

· Perl now supports SystemTap's "dtrace" compatibility layer and an issue with linking
"miniperl" has been fixed in the process.

· perldoc now uses "less -R" instead of "less" for improved behaviour in the face of
"groff"'s new usage of ANSI escape codes.

· "perl -V" now reports use of the compile-time options "USE_PERL_ATOF" and
"USE_ATTRIBUTES_FOR_PERLIO".

· 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.

Internal Changes

Each release of Perl sees numerous internal changes which shouldn't affect day to day
usage but may still be notable for developers working with Perl's source code.

· 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.

· The internal structure of the dual-life modules traditionally found in the lib/ and
ext/ directories in the perl source has changed significantly. Where possible, dual-
lifed modules have been extracted from lib/ and ext/.

Dual-lifed modules maintained by Perl's developers as part of the Perl core now live
in dist/. Dual-lifed modules maintained primarily on CPAN now live in cpan/. When
reporting a bug in a module located under cpan/, please send your bug report directly
to the module's bug tracker or author, rather than Perl's bug tracker.

· "\N{...}" now compiles better, always forces UTF-8 internal representation

Perl's developers have fixed several problems with the recognition of "\N{...}"
constructs. As part of this, perl will store any scalar or regex containing
"\N{name}" or "\N{U+code point}" in its definition in UTF-8 format. (This was true
previously for all occurrences of "\N{name}" that did not use a custom translator, but
now it's always true.)

· Perl_magic_setmglob now knows about globs, fixing RT #71254.

· "SVt_RV" no longer exists. RVs are now stored in IVs.

· "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" 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" now calls "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".

· Perl now exports the functions "PerlIO_find_layer" and "PerlIO_list_alloc".

· "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 dereference 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.

· 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.

Testing

Testing improvements
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.

Test harness flexibility
It's now possible to override "PERL5OPT" and friends in t/TEST

Test watchdog
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.

New Tests
Perl's developers have added a number of new tests to the core. In addition to the items
listed below, many modules updated from CPAN incorporate new tests.

· Significant cleanups to core tests to ensure that language and interpreter features
are not used before they're tested.

· "make test_porting" now runs a number of important pre-commit checks which might be of
use to anyone working on the Perl core.

· t/porting/podcheck.t automatically checks the well-formedness of POD found in all .pl,
.pm and .pod files in the MANIFEST, other than in dual-lifed modules which are
primarily maintained outside the Perl core.

· t/porting/manifest.t now tests that all files listed in MANIFEST are present.

· t/op/while_readdir.t tests that a bare readdir in while loop sets $_.

· t/comp/retainedlines.t checks that the debugger can retain source lines from "eval".

· t/io/perlio_fail.t checks that bad layers fail.

· t/io/perlio_leaks.t checks that PerlIO layers are not leaking.

· t/io/perlio_open.t checks that certain special forms of open work.

· t/io/perlio.t includes general PerlIO tests.

· t/io/pvbm.t checks that there is no unexpected interaction between the internal types
"PVBM" and "PVGV".

· t/mro/package_aliases.t checks that mro works properly in the presence of aliased
packages.

· t/op/dbm.t tests "dbmopen" and "dbmclose".

· t/op/index_thr.t tests the interaction of "index" and threads.

· t/op/pat_thr.t tests the interaction of esoteric patterns and threads.

· t/op/qr_gc.t tests that "qr" doesn't leak.

· t/op/reg_email_thr.t tests the interaction of regex recursion and threads.

· t/op/regexp_qr_embed_thr.t tests the interaction of patterns with embedded "qr//" and
threads.

· t/op/regexp_unicode_prop.t tests Unicode properties in regular expressions.

· t/op/regexp_unicode_prop_thr.t tests the interaction of Unicode properties and
threads.

· t/op/reg_nc_tie.t tests the tied methods of "Tie::Hash::NamedCapture".

· t/op/reg_posixcc.t checks that POSIX character classes behave consistently.

· t/op/re.t checks that exportable "re" functions in universal.c work.

· t/op/setpgrpstack.t checks that "setpgrp" works.

· t/op/substr_thr.t tests the interaction of "substr" and threads.

· t/op/upgrade.t checks that upgrading and assigning scalars works.

· t/uni/lex_utf8.t checks that Unicode in the lexer works.

· t/uni/tie.t checks that Unicode and "tie" work.

· t/comp/final_line_num.t tests whether line numbers are correct at EOF

· t/comp/form_scope.t tests format scoping.

· t/comp/line_debug.t tests whether "@{"_<$file"}" works.

· t/op/filetest_t.t tests if -t file test works.

· t/op/qr.t tests "qr".

· t/op/utf8cache.t tests malfunctions of the utf8 cache.

· t/re/uniprops.t test unicodes "\p{}" regex constructs.

· t/op/filehandle.t tests some suitably portable filetest operators to check that they
work as expected, particularly in the light of some internal changes made in how
filehandles are blessed.

· t/op/time_loop.t tests that unix times greater than "2**63", which can now be handed
to "gmtime" and "localtime", do not cause an internal overflow or an excessively long
loop.

New or Changed Diagnostics

New Diagnostics
· 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.

· Perl 5.12 provides a number of new diagnostic messages to help you write better code.
See perldiag for details of these new messages.

· "Bad plugin affecting keyword '%s'"

· "gmtime(%.0f) too large"

· "Lexing code attempted to stuff non-Latin-1 character into Latin-1 input"

· "Lexing code internal error (%s)"

· "localtime(%.0f) too large"

· "Overloaded dereference did not return a reference"

· "Overloaded qr did not return a REGEXP"

· "Perl_pmflag() is deprecated, and will be removed from the XS API"

· "lvalue attribute ignored after the subroutine has been defined"

This new warning is issued when one attempts to mark a subroutine as lvalue after
it has been defined.

· Perl now warns you if "++" or "--" are unable to change the value because it's
beyond the limit of representation.

This uses a new warnings category: "imprecision".

· "lc", "uc", "lcfirst", and "ucfirst" warn when passed undef.

· "Show constant in "Useless use of a constant in void context""

· "Prototype after '%s'"

· "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.

· The fatal error "Malformed UTF-8 returned by \N" is now produced if the
"charnames" handler returns malformed UTF-8.

· If an unresolved named character or sequence was encountered when compiling a
regex pattern then the fatal error "\N{NAME} must be resolved by the lexer" is now
produced. This can happen, for example, when using a single-quotish context like
"$re = '\N{SPACE}'; /$re/;". See perldiag for more examples of how the lexer can
get bypassed.

· "Invalid hexadecimal number in \N{U+...}" is a new fatal error triggered when the
character constant represented by "..." is not a valid hexadecimal number.

· The new meaning of "\N" as "[^\n]" is not valid in a bracketed character class,
just like "." in a character class loses its special meaning, and will cause the
fatal error "\N in a character class must be a named character: \N{...}".

· The rules on what is legal for the "..." in "\N{...}" have been tightened up so
that unless the "..." begins with an alphabetic character and continues with a
combination of alphanumerics, dashes, spaces, parentheses or colons then the
warning "Deprecated character(s) in \N{...} starting at '%s'" is now issued.

· The warning "Using just the first characters returned by \N{}" will be issued if
the "charnames" handler returns a sequence of characters which exceeds the limit
of the number of characters that can be used. The message will indicate which
characters were used and which were discarded.

Changed Diagnostics
A number of existing diagnostic messages have been improved or corrected:

· A new warning category "illegalproto" allows finer-grained control of warnings around
function prototypes.

The two warnings:

"Illegal character in prototype for %s : %s"
"Prototype after '%c' for %s : %s"

have been moved from the "syntax" top-level warnings category into a new first-level
category, "illegalproto". These two warnings are currently the only ones emitted
during parsing of an invalid/illegal prototype, so one can now use

no warnings 'illegalproto';

to suppress only those, but not other syntax-related warnings. Warnings where
prototypes are changed, ignored, or not met are still in the "prototype" category as
before.

· "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.

· "Illegal character in prototype" warning is now more precise when reporting illegal
characters after _

· mro merging error messages 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.

· Perl now explicitly points to $. when it causes an uninitialized warning for ranges in
scalar context.

· "split" now warns when called in void context.

· "printf"-style functions called with too few arguments will now issue the warning
"Missing argument in %s" [perl #71000]

· Perl now properly returns a syntax error instead of segfaulting if "each", "keys", or
"values" is used without an argument.

· "tell()" now fails properly if called without an argument and when no previous file
was read.

"tell()" now returns "-1", and sets errno to "EBADF", thus restoring the 5.8.x
behaviour.

· "overload" no longer implicitly unsets fallback on repeated 'use overload' lines.

· POSIX::strftime() can now handle Unicode characters in the format string.

· The "syntax" category was removed from 5 warnings that should only be in "deprecated".

· Three fatal "pack"/"unpack" error messages have been normalized to "panic: %s"

· "Unicode character is illegal" has been rephrased to be more accurate

It now reads "Unicode non-character is illegal in interchange" and the perldiag
documentation has been expanded a bit.

· Currently, all but the first of the several characters that the "charnames" handler
may return are discarded when used in a regular expression pattern bracketed character
class. If this happens then the warning "Using just the first character returned by
\N{} in character class" will be issued.

· The warning "Missing right brace on \N{} or unescaped left brace after \N. Assuming
the latter" will be issued if Perl encounters a "\N{" but doesn't find a matching "}".
In this case Perl doesn't know if it was mistakenly omitted, or if "match non-newline"
followed by "match a "{"" was desired. It assumes the latter because that is actually
a valid interpretation as written, unlike the other case. If you meant the former,
you need to add the matching right brace. If you did mean the latter, you can silence
this warning by writing instead "\N\{".

· "gmtime" and "localtime" called with numbers smaller than they can reliably handle
will now issue the warnings "gmtime(%.0f) too small" and "localtime(%.0f) too small".

The following diagnostic messages have been removed:

· "Runaway format"

· "Can't locate package %s for the parents of %s"

In general this warning 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"

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. It also now handles C++
style comments ("//") properly in enums.

· perl5db.pl now supports "LVALUE" subroutines. Additionally, the debugger now
correctly handles proxy constant subroutines, and subroutine stubs.

· perlbug now uses %Module::CoreList::bug_tracker to print out upstream bug tracker
URLs. If a user identifies a particular module as the topic of their bug report and
we're able to divine the URL for its upstream bug tracker, perlbug now 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 the upstream author.

perlbug no longer reports "Message sent" when it hasn't actually sent the message

· perlthanks is a new utility for sending non-bug-reports to the authors and maintainers
of Perl. Getting nothing but bug reports can become a bit demoralising. If Perl 5.12
works well for you, please try out perlthanks. It will make the developers smile.

· Perl's developers have fixed bugs in a2p having to do with the "match()" operator in
list context. Additionally, a2p no longer generates code that uses the $[ variable.

Selected Bug Fixes

· U+0FFFF is now a legal character in regular expressions.

· pp_qr now always returns a new regexp SV. Resolves RT #69852.

Instead of returning a(nother) reference to the (pre-compiled) regexp in the optree,
use reg_temp_copy() to create a copy of it, and return a reference to that. This
resolves issues about Regexp::DESTROY not being called in a timely fashion (the
original bug tracked by RT #69852), as well as bugs related to blessing regexps, and
of assigning to regexps, as described in correspondence added to the ticket.

It transpires that we also need to undo the SvPVX() sharing when ithreads cloning a
Regexp SV, because mother_re is set to NULL, instead of a cloned copy of the
mother_re. This change might fix bugs with regexps and threads in certain other
situations, but as yet neither tests nor bug reports have indicated any problems, so
it might not actually be an edge case that it's possible to reach.

· Several compilation errors and segfaults when perl was built with "-Dmad" were fixed.

· Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.

· "-t" should only return TRUE for file handles connected to a TTY

The Microsoft C version of "isatty()" returns TRUE for all character mode devices,
including the /dev/null-style "nul" device and printers like "lpt1".

· Fixed a regression caused by commit fafafbaf which caused a panic during parameter
passing [perl #70171]

· On systems which in-place edits without backup files, -i'*' now works as the
documentation says it does [perl #70802]

· Saving and restoring magic flags no longer loses readonly flag.

· The malformed syntax "grep EXPR LIST" (note the missing comma) no longer causes abrupt
and total failure.

· Regular expressions compiled with "qr{}" literals properly set "$'" when matching
again.

· Using named subroutines with "sort" should no longer lead to bus errors [perl #71076]

· Numerous bugfixes catch small issues caused by the recently-added Lexer API.

· Smart match against @_ sometimes gave false negatives. [perl #71078]

· $@ may now be assigned a read-only value (without error or busting the stack).

· "sort" called recursively from within an active comparison subroutine no longer causes
a bus error if run multiple times. [perl #71076]

· Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)

· @_ and $_ no longer leak under threads (RT #34342 and #41138, also #70602, #70974)

· "-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. (This fix
is also present in 5.10.1)

· 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

· 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

· Perl now includes previously missing files from the Unicode Character Database.

· Perl now honors "TMPDIR" when opening an anonymous temporary file.

Platform Specific Changes

Perl is incredibly portable. In general, if a platform has a C compiler, someone has
ported Perl to it (or will soon). We're happy to announce that Perl 5.12 includes support
for several new platforms. At the same time, it's time to bid farewell to some (very) old
friends.

New Platforms
Haiku
Perl's developers have merged patches from Haiku's maintainers. Perl should now build
on Haiku.

MirOS BSD
Perl should now build on MirOS BSD.

Discontinued Platforms
Domain/OS
MiNT
Tenon MachTen

Updated Platforms
AIX
· Removed libbsd for AIX 5L and 6.1. Only "flock()" was used from libbsd.

· Removed libgdbm for AIX 5L and 6.1 if libgdbm < 1.8.3-5 is installed. The libgdbm
is delivered as an optional package with the AIX Toolbox. Unfortunately the
versions below 1.8.3-5 are broken.

· Hints changes mean that AIX 4.2 should work again.

Cygwin
· Perl now supports IPv6 on Cygwin 1.7 and newer.

· 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.

Darwin (Mac OS X)
· Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6), as it's still
buggy.

· Correct infelicities in the regexp used to identify buggy locales on Darwin 8 and
9 (Mac OS X 10.4 and 10.5, respectively).

DragonFly BSD
· Fix thread library selection [perl #69686]

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.

NetBSD
· Hints now supports versions 5.*.

OpenVMS
· "-UDEBUGGING" is now the default on VMS.

Like it has been everywhere else for ages and ages. Also make command-line
selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before the only
way to turn it off was by saying no in answer to the interactive question.

· The default pipe buffer size on VMS has been updated to 8192 on 64-bit systems.

· 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.

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.

Windows
· Perl 5.12 supports Windows 2000 and later. The supporting code for legacy versions
of Windows is still included, but will be removed during the next development
cycle.

· Initial support for building Perl with MinGW-w64 is now available.

· perl.exe now includes a manifest resource to specify the "trustInfo" settings for
Windows Vista and later. Without this setting Windows would treat perl.exe as a
legacy application and apply various heuristics like redirecting access to
protected file system areas (like the "Program Files" folder) to the users
"VirtualStore" instead of generating a proper "permission denied" error.

The manifest resource also requests the Microsoft Common-Controls version 6.0
(themed controls introduced in Windows XP). Check out the Win32::VisualStyles
module on CPAN to switch back to old style unthemed controls for legacy
applications.

· The "-t" filetest operator now only returns true if the filehandle is connected to
a console window. In previous versions of Perl it would return true for all
character mode devices, including NUL and LPT1.

· The "-p" filetest operator now works correctly, and the Fcntl::S_IFIFO constant is
defined when Perl is compiled with Microsoft Visual C. In previous Perl versions
"-p" always returned a false value, and the Fcntl::S_IFIFO constant was not
defined.

This bug is specific to Microsoft Visual C and never affected Perl binaries built
with MinGW.

· The socket error codes are now more widely supported: The POSIX module will
define the symbolic names, like POSIX::EWOULDBLOCK, and stringification of socket
error codes in $! works as well now;

C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
A non-blocking socket operation could not be completed immediately.

· flock() will now set sensible error codes in $!. Previous Perl versions copied
the value of $^E into $!, which caused much confusion.

· select() now supports all empty "fd_set"s more correctly.

· '.\foo' and '..\foo' were treated differently than './foo' and '../foo' by "do"
and "require" [RT #63492].

· Improved message window handling means that "alarm" and "kill" messages will no
longer be dropped under race conditions.

· Various bits of Perl's build infrastructure are no longer converted to win32 line
endings at release time. If this hurts you, please report the problem with the
perlbug program included with perl.

Known Problems

This is a list of some significant unfixed bugs, which are regressions from either 5.10.x
or 5.8.x.

· Some CPANPLUS tests may fail if there is a functioning file ../../cpanp-run-perl
outside your build directory. The failure shouldn't imply there's a problem with the
actual functional software. The bug is already fixed in [RT #74188] and is scheduled
for inclusion in perl-v5.12.1.

· "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

· Some regexes may run much more slowly when run in a child thread compared with the
thread the pattern was compiled into [RT #55600].

· Things like ""\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/" will appear
to hang as they get into a very long running loop [RT #72998].

· Several porters have reported mysterious crashes when Perl's entire test suite is run
after a build on certain Windows 2000 systems. When run by hand, the individual tests
reportedly work fine.

Errata

· 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;

Acknowledgements

Perl 5.12.0 represents approximately two years of development since Perl 5.10.0 and
contains over 750,000 lines of changes across over 3,000 files from over 200 authors and
committers.

Perl continues to flourish into its third decade thanks to a vibrant community of users
and developers. The following people are known to have contributed the improvements that
became Perl 5.12.0:

Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell, Adriano Ferreira,
AEvar Arnfjoer` Bjarmason, Alan Grover, Alexandr Ciornii, Alex Davies, Alex Vandiver,
Andreas Koenig, Andrew Rodland, [email protected], Andy Armstrong, Andy Dougherty, Jose
AUGUSTE-ETIENNE, Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey, Chip Salzenberg, Chris
'BinGOs' Williams, Christoph Lamprecht, Chris Williams, chromatic, Claes Jakobsson, Craig
A. Berry, Dan Dascalescu, Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan
Kogai, Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden, David
Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis Kaarsemaker, Dintelmann,
Peter, Dominic Dunlop, Dr.Ruud, Duke Leto, Enrico Sorcinelli, Eric Brine, Father
Chrysostomos, Florian Ragwitz, Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T.
Dairiki, George Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden, Ian Goodacre, Igor
Sutton, Ingo Weinhold, James Bence, James Mastros, Jan Dubois, Jari Aalto, Jarkko
Hietaniemi, Jay Hannah, Jerry Hedden, Jesse Vincent, Jim Cromie, Jody Belka, John E.
Malmberg, John Malmberg, John Peacock, John Peacock via RT, John P. Linderman, John
Wright, Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken Williams,
Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard, Lubomir Rintel, Luke Ross,
Marcel Gruenauer, Marcus Holland-Moritz, Mark Jason Dominus, Marko Asplund, Martin Hasch,
Mashrab Kuvatov, Matt Kraai, Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell,
Michael G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz, Nicholas
Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon, Paul Fenwick, Paul Gaborit,
Paul Green, Paul Johnson, Paul Marquess, Philip Hazel, Philippe Bruhat, Rafael Garcia-
Suarez, Rainer Tammer, Rajesh Mandalemula, Reini Urban, Renee Baecker, Ricardo Signes,
Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto Kankkunen, Robert May,
Roberto C. Sanchez, Robin Barker, SADAHIRO Tomoyuki, Salvador Ortiz Garcia, Sam Vilain,
Scott Lanning, Sebastien Aperghis-Tramoni, Sergio Durigan Junior, Shlomi Fish, Simon
'corecode' Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Mueller, Steffen Ullrich,
Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels, The Doctor, Tim Bunce, Tim
Jenness, Todd Rinaldo, Tom Christiansen, Tom Hukins, Tom Wyant, Tony Cook, Torsten
Schoenfeld, Tye McQueen, Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus

This is woefully incomplete as it's automatically generated from version control history.
In particular, it doesn't include the names of the (very much appreciated) contributors
who reported issues in previous versions of Perl that helped make Perl 5.12.0 better. For
a more complete list of all of Perl's historical contributors, please see the "AUTHORS"
file in the Perl 5.12.0 distribution.

Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez deserve special thanks for
their brilliant and substantive ongoing contributions. Nicholas personally authored over
30% of the patches since 5.10.0. Rafael comes in second in patch authorship with 11%, but
is first by a long shot in committing patches authored by others, pushing 44% of the
commits since 5.10.0 in this category, often after providing considerable coaching to the
patch authors. These statistics in no way comprise all of their contributions, but express
in shorthand that we couldn't have done it without them.

Many of the changes included in this version originated in the CPAN modules included in
Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

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 [email protected] to be
analyzed 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
[email protected]. This points to a closed subscription unarchived mailing
list, which includes all the core committers, who will 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.

Use perl5120delta online using onworks.net services