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perl5120delta (1)


perl5120delta - what is new for perl v5.12.0


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Perl Programmers Reference Guide                 PERL5120DELTA(1)

     perl5120delta - what is new for perl v5.12.0

     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:

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

     o   $VERSION is set at compile time

     o   $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.

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

     o   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

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  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;


         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
     <> 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 allow a completely
     non-Perl sublanguage to be parsed inline, with the correct
     ops cleanly generated.

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     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

  "\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

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     "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

     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

  "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

  "delete local"
     "delete local" now allows you to locally delete a hash

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  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

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  @INC reorganization
     In @INC, "ARCHLIB" and "PRIVLIB" now occur after 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

  REGEXPs are now first class
     Internally, Perl now treates 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)".)

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  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

     Changes to type-based dispatch

     The smart match operator "~~" is no longer commutative. The
     behaviour of a smart match now depends primarily on the type
     of its right hand argument. Moreover, its semantics have
     been adjusted for greater consistency or usefulness in
     several cases. While the general backwards compatibility is
     maintained, several changes must be noted:

     o   Code references with an empty prototype are no longer
         treated specially.  They are passed an argument like the
         other code references (even if they choose to ignore

     o   "%hash ~~ sub {}" and "@array ~~ sub {}" now test that
         the subroutine returns a true value for each key of the
         hash (or element of the array), instead of passing the
         whole hash or array as a reference to the subroutine.

     o   Due to the commutativity breakage, code references are
         no longer treated specially when appearing on the left
         of the "~~" operator, but like any vulgar scalar.

     o   "undef ~~ %hash" is always false (since "undef" can't be
         a key in a hash). No implicit conversion to "" is done
         (as was the case in perl 5.10.0).

     o   "$scalar ~~ @array" now always distributes the smart
         match across the elements of the array. It's true if one
         element in @array verifies "$scalar ~~ $element". This
         is a generalization of the old behaviour that tested
         whether the array contained the scalar.

     The full dispatch table for the smart match operator is
     given in "Smart matching in detail" in perlsyn.

     Smart match and overloading

     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

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     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

  Other potentially incompatible changes
     o   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.

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

     o   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".

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

     o   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.

     o   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.

     o   As part of the "ExtUtils::MakeMaker" upgrade, the
         "ExtUtils::MakeMaker::bytes" and
         "ExtUtils::MakeMaker::vmsish" modules have been removed
         from this distribution.

     o   "Module::CoreList" no longer contains the %:patchlevel

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     o   "length undef" now returns undef.

     o   Unsupported private C API functions are now declared
         "static" to prevent leakage to Perl's public API.

     o   To support the bootstrapping process, miniperl no longer
         builds with UTF-8 support in the regexp engine.

         This allows a build to complete with PERL_UNICODE set
         and a UTF-8 locale.  Without this there's a
         bootstrapping problem, as miniperl can't load the UTF-8
         components of the regexp engine, because they're not yet

     o   miniperl's @INC is now restricted to just "-I...", the
         split of $ENV{PERL5LIB}, and "".""

     o   A space or a newline is now required after a "#line XXX"

     o   Tied filehandles now have an additional method EOF which
         provides the EOF type.

     o   To better match all other flow control statements,
         "foreach" may no longer be used as an attribute.

     o   Perl's command-line switch "-P", which was deprecated in
         version 5.10.0, has now been removed.

     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

     The following items are now deprecated:

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         "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

         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 "=".

         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
         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

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         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 reprecussions 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/ 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

             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" is no longer part of Perl's public API.

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         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,,,,,,,,,,,,,,,,,,,,,,,,,,,, and 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

     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.

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     It now is defined as an extended grapheme cluster. (See
     <>).  Anything matched
     previously and that made sense will continue to be accepted.

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

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

     o   "\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.

     o   "\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

     "\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

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     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 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:

     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

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

     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.

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     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" 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.

         Version 2.024 has been added to the Perl core.

         "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" 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.

         Version 1.40 has been added to the Perl core.

         Version 1.03 has been added to the Perl core.

         Version 2.4 has been added to the Perl core.

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         Version 0.003 has been added to the Perl core.

  Updated Pragmata
         Upgraded from version 2.13 to 2.15.

         Upgraded from version 0.22 to 0.23.

         "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.

         Upgraded from version 1.13 to 1.20.

         "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.

         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

         Upgraded from version 1.11 to 1.16.

         "less" now includes the "stash_name" method to allow

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         subclasses of "less" to pick where in %^H to store their

         Upgraded from version 0.02 to 0.03.

         Upgraded from version 0.5565 to 0.62.

         "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

         Upgraded from version 1.00 to 1.02.

         "overload" now allow overloading of 'qr'.

         Upgraded from version 1.06 to 1.10.

         Upgraded from version 1.67 to 1.75.

         Upgraded from version 1.14 to 1.32.

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

         Upgraded from version 0.74 to 0.82.

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

         Upgraded from version 1.06 to 1.09.

  Updated Modules
         Upgraded from version 0.24 to 0.38.

         Upgraded from version 1.38 to 1.54.

         Upgraded from version 0.79 to 0.87.

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         Upgraded from version 5.63 to 5.70.

         Upgraded from version 0.74 to 0.78.

         Upgraded from version 1.05 to 1.12.

         Upgraded from version 0.83 to 0.96.

         Upgraded from version 1.09 to 1.11_01.

         Upgraded from version 3.29 to 3.48.

         Upgraded from version 0.33 to 0.36.

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

         Upgraded from version 2.008 to 2.024.

         Upgraded from version 1.9205 to 1.94_56.

         Upgraded from version 0.84 to 0.90.

         Upgraded from version 0.06_02 to 0.46.

         Upgraded from version 2.121_14 to 2.125.

         Upgraded from version 1.816_1 to 1.820.

         Upgraded from version 3.13 to 3.19.

         Upgraded from version 1.15 to 1.16.

         Upgraded from version 2.36_01 to 2.39.


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         Upgraded from version 5.45 to 5.47.

         Upgraded from version 2.23 to 2.39.

         Upgraded from version 5.62 to 5.64_01.

         Upgraded from version 0.21 to 0.27.

         Upgraded from version 1.13 to 1.16.

         Upgraded from version 0.2 to 0.22.

         Upgraded from version 1.44 to 1.55.

         Upgraded from version 6.42 to 6.56.

         Upgraded from version 1.51_01 to 1.57.

         Upgraded from version 2.18_02 to 2.21.

         Upgraded from version 0.14 to 0.24.

         Upgraded from version 2.04 to 2.08_01.

         Upgraded from version 0.18 to 0.22.

         Upgraded from version 0.82 to 0.84.

         Upgraded from version 1.07 to 1.08.

         Upgraded from version 2.37 to 2.38.

         Upgraded from version 1.23_01 to 1.25_02.

         Upgraded from version 1.07 to 1.10.

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         Upgraded from version 0.40_1 to 0.54.

         Upgraded from version 1.05 to 2.01.

         Upgraded from version 1.12 to 1.14.

         Upgraded from version 0.18 to 0.21.

         Upgraded from version 0.01 to 0.02.

         Upgraded from version 0.04 to 0.06.

         Upgraded from version 1.88 to 1.89_01.

         Upgraded from version 0.16 to 0.19.

         Upgraded from version 0.21 to 0.24.

         Upgraded from version 1.37 to 1.56.

         Upgraded from version 1.01_02 to 1.01_03.

         Upgraded from version 3.07_01 to 3.08.

         Upgraded from version 0.2808_01 to 0.3603.

         Upgraded from version 2.12 to 2.29.

         Upgraded from version 0.12 to 0.16.

         Upgraded from version 0.22 to 0.34.

         Upgraded from version 0.01 to 0.06.


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         Upgraded from version 3.6 to 3.9.

         Upgraded from version 2.33 to 2.36.

         Upgraded from version 0.60_01 to 0.64.

         Upgraded from version 0.32 to 0.36.

         Upgraded from version 0.01 to 0.02.

         Upgraded from version 1.04 to 1.06.

         Upgraded from version 1.35 to 1.37.

         Upgraded from version 3.14_02 to 3.15_02.

         Upgraded from version 0.01 to 1.02.

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

         Upgraded from version 3.05 to 3.13.

         Upgraded from version 2.12 to 2.22.

         Upgraded from version 1.11 to 1.17.

         Upgraded from version 2.18 to 2.22.

         Upgraded from version 2.13 to 2.16.

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

         Upgraded from version 0.22 to 0.27.

         Upgraded from version 1.12 to 2.02.

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         Upgraded from version 0.18 to 0.20.

         Upgraded from version 1.25 to 1.25_02.

         Upgraded from version 2.64 to 3.17.

         Upgraded from version 0.72 to 0.94.

         Upgraded from version 2.0.0 to 2.02.

         Upgraded from version 3.26 to 3.27.

         Upgraded from version 3.03 to 3.03_01.

         Upgraded from version 2.00 to 2.11.

         Upgraded from version 2.01 to 2.09.

         Upgraded from version 1.37 to 1.38.

         Upgraded from version 1.9711 to 1.9719.

         Upgraded from version 1.18 to 1.1901_01.

         Upgraded from version 1.12 to 1.15.

         Upgraded from version 0.52 to 0.52_01.

         Upgraded from version 1.02 to 1.03.

         Upgraded from version 0.34 to 0.39.

         Upgraded from version 0.1001_01 to 0.1101.


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         Upgraded from version 0.08 to 0.10.

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

         Removed from the Perl core.  Prior version was 'undef'.

         Removed from the Perl core.  Prior version was 5.50.

         Removed from the Perl core.  Prior version was 'undef'.

         Removed from the Perl core.  Prior version was 1.03.

         Removed from the Perl core.  Prior version was 6.42.

         Removed from the Perl core.  Prior version was 6.42.

         Removed from the Perl core.  Prior version was 2.3.

         Removed from the Perl core.  Prior version was 0.02.

         Removed from the Perl core.  Prior version was 0.02.

         Removed from the Perl core.  Prior version was 0.01.

         Removed from the Perl core.  Prior version was 0.01.

         Removed from the Perl core.  Prior version was 0.26_01.

         Removed from the Perl core.  Prior version was 0.01.

         Removed from the Perl core.  Prior version was 1.1.

  Deprecated Modules and Pragmata
     See "Deprecated Modules" above.

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

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

     o   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.

     o   perlrepository describes how to access the perl source
         using the git version control system.

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

  Changes to Existing Documentation
     o   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.

     o   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.

     o   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.

     o   Documented -X overloading.

     o   Documented that "when()" treats specially most of the
         filetest operators

     o   Documented "when" as a syntax modifier.

     o   Eliminated "Old Perl threads tutorial", which described
         5005 threads.

         pod/perlthrtut.pod is the same material reworked for

     o   Correct previous documentation: v-strings are not

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         With version objects, we need them to use MODULE VERSION
         syntax. This patch removes the deprecation notice.

     o   Security contact information is now part of perlsec.

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

         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

     o   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

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

     o   The documentation for $1 in perlvar.pod has been

     o   "\N{U+wide hex char}" is now documented.

Selected Performance Enhancements
     o   A new internal cache means that "isa()" will often be

     o   The implementation of "C3" Method Resolution Order has
         been optimised - linearisation for classes with single
         inheritance is 40% faster. Performance for multiple
         inheritance is unchanged.

     o   Under "use locale", the locale-relevant information is
         now cached on read-only values, such as the list
         returned by "keys %hash". This makes operations such as
         "sort keys %hash" in the scope of "use locale" much

     o   Empty "DESTROY" methods are no longer called.

     o   "Perl_sv_utf8_upgrade()" is now faster.

     o   "keys" on empty hash is now faster.

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

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

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

     o   If "vendorlib" and "vendorarch" are the same, then they
         are only added to @INC once.

     o   $Config{usedevel} and the C-level "PERL_USE_DEVEL" are
         now defined if perl is built with  "-Dusedevel".

     o   Configure will enable use of "-fstack-protector", to
         provide protection against stack-smashing attacks, if
         the compiler supports it.

     o   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.

     o   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".

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

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

     o   "perl -V" now reports use of the compile-time options

     o   As part of the flattening of ext, all extensions on all

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         platforms are built by This replaces the
         Unix-specific ext/util/make_ext, VMS-specific and Win32-specific win32/

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.

     o   The J.R.R. Tolkien quotes at the head of C source file
         have been checked and proper citations added, thanks to
         a patch from Tom Christiansen.

     o   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.

     o   "\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+wide hex char}" in its definition in
         UTF-8 format. (This was true previously for all
         occurences of "\N{name}" that did not use a custom
         translator, but now it's always true.)

     o   Perl_magic_setmglob now knows about globs, fixing RT

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

     o   "Perl_vcroak()" now accepts a null first argument. In
         addition, a full audit was made of the "not NULL"
         compiler annotations, and those for several other
         internal functions were corrected.

     o   New macros "dSAVEDERRNO", "dSAVE_ERRNO", "SAVE_ERRNO",
         "RESTORE_ERRNO" have been added to formalise the
         temporary saving of the "errno" variable.

     o   The function "Perl_sv_insert_flags" has been added to

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         augment "Perl_sv_insert".

     o   The function "Perl_newSV_type(type)" has been added,
         equivalent to "Perl_newSV()" followed by

     o   The function "Perl_newSVpvn_flags()" has been added,
         equivalent to "Perl_newSVpvn()" and then performing the
         action relevant to the flag.

         Two flag bits are currently supported.

         o   "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.

         o   "SVs_TEMP" now calls "Perl_sv_2mortal()" on the new

         There is also a wrapper that takes constant strings,

     o   The function "Perl_croak_xs_usage" has been added as a
         wrapper to "Perl_croak".

     o   Perl now exports the functions "PerlIO_find_layer" and

     o   "PL_na" has been exterminated from the core code,
         replaced by local STRLEN temporaries, or "*_nolen()"
         calls. Either approach is faster than "PL_na", which is
         a pointer dereference into the interpreter structure
         under ithreads, and a global variable otherwise.

     o   "Perl_mg_free()" used to leave freed memory accessible
         via "SvMAGIC()" on the scalar. It now updates the linked
         list to remove each piece of magic as it is freed.

     o   Under ithreads, the regex in "PL_reg_curpm" is now
         reference counted. This eliminates a lot of hackish
         workarounds to cope with it not being reference counted.

     o   "Perl_mg_magical()" would sometimes incorrectly turn on
         "SvRMAGICAL()".  This has been fixed.

     o   The public IV and NV flags are now not set if the string
         value has trailing "garbage". This behaviour is
         consistent with not setting the public IV or NV flags if
         the value is out of range for the type.

     o   Uses of "Nullav", "Nullcv", "Nullhv", "Nullop", "Nullsv"

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         etc have been replaced by "NULL" in the core code, and
         non-dual-life modules, as "NULL" is clearer to those
         unfamiliar with the core code.

     o   A macro MUTABLE_PTR(p) has been added, which on (non-
         pedantic) gcc will not cast away "const", returning a
         "void *". Macros "MUTABLE_SV(av)", "MUTABLE_SV(cv)" etc
         build on this, casting to "AV *" etc without casting
         away "const". This allows proper compile-time auditing
         of "const" correctness in the core, and helped picked up
         some errors (now fixed).

     o   Macros "mPUSHs()" and "mXPUSHs()" have been added, for
         pushing SVs on the stack and mortalizing them.

     o   Use of the private structure "mro_meta" has changed
         slightly. Nothing outside the core should be accessing
         this directly anyway.

     o   A new tool, Porting/ 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 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

             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

     Test watchdog

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         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.

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

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

     o   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.

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

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

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

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

     o   t/io/perlio_leaks.t checks that PerlIO layers are not

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

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

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

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

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

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

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

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

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

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

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

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

     o   t/op/reg_nc_tie.t tests the tied methods of

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

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

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

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

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

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

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

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

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

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

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

     o   t/op/qr.t tests "qr".

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

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

     o   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.

     o   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
     o   SV allocation tracing has been added to the diagnostics
         enabled by "-Dm".  The tracing can alternatively output
         via the "PERL_MEM_LOG" mechanism, if that was enabled
         when the perl binary was compiled.

     o   Smartmatch resolution tracing has been added as a new
         diagnostic. Use "-DM" to enable it.

     o   A new debugging flag "-DB" now dumps subroutine
         definitions, leaving "-Dx" for its original purpose of
         dumping syntax trees.

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

         o   "Bad plugin affecting keyword '%s'"

         o   "gmtime(%.0f) too large"

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

         o   "Lexing code internal error (%s)"

         o   "localtime(%.0f) too large"

         o   "Overloaded dereference did not return a reference"

         o   "Overloaded qr did not return a REGEXP"

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

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

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

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

             This uses a new warnings category: "imprecision".

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

         o   "Show constant in "Useless use of a constant in void

         o   "Prototype after '%s'"

         o   "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.

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

         o   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.

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

         o   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{...}".

         o   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,

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             dashes, spaces, parentheses or colons then the
             warning "Deprecated character(s) in \N{...} starting
             at '%s'" is now issued.

         o   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:

     o   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.

     o   "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.

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

     o   mro merging error messages are now very similar to those
         produced by Algorithm::C3.

     o   Amelioration of the error message "Unrecognized
         character %s in column %d"

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         Changes the error message to "Unrecognized character %s;
         marked by <-- HERE after %s<-- HERE near column %d".
         This should make it a little simpler to spot and correct
         the suspicious character.

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

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

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

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

     o   "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.

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

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

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

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

     o   "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.

     o   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.

     o   The warning "Missing right brace on \N{} or unescaped
         left brace after \N.  Assuming the latter" will be

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         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\{".

     o   "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:

     o   "Runaway format"

     o   "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.

     o   "v-string in use/require is non-portable"

Utility Changes
     o   h2ph now looks in "include-fixed" too, which is a recent
         addition to gcc's search path.

     o   h2xs no longer incorrectly treats enum values like
         macros.  It also now handles C++ style comments ("//")
         properly in enums.

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

     o   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

     o   perlthanks is a new utility for sending non-bug-reports

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         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.

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

     o   pp_qr now always returns a new regexp SV. Resolves RT

         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.

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

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

     o   "-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".

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

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

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

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

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

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

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

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

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

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

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

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

     o   "-I" on shebang line now adds directories in front of
         @INC as documented, and as does "-I" when specified on
         the command-line.

     o   "kill" is now fatal when called on non-numeric process
         identifiers.  Previously, an "undef" process identifier
         would be interpreted as a request to kill process 0,
         which would terminate the current process group on POSIX
         systems. Since process identifiers are always integers,
         killing a non-numeric process is now fatal.

     o   5.10.0 inadvertently disabled an optimisation, which
         caused a measurable performance drop in list assignment,
         such as is often used to assign function parameters from
         @_. The optimisation has been re-instated, and the
         performance regression fixed. (This fix is also present
         in 5.10.1)

     o   Fixed memory leak on "while (1) { map 1, 1 }" [RT

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     o   Some potential coredumps in PerlIO fixed [RT

     o   The debugger now works with lvalue subroutines.

     o   The debugger's "m" command was broken on modules that
         defined constants [RT #61222].

     o   "crypt" and string complement could return tainted
         values for untainted arguments [RT #59998].

     o   The "-i".suffix command-line switch now recreates the
         file using restricted permissions, before changing its
         mode to match the original file. This eliminates a
         potential race condition [RT #60904].

     o   On some Unix systems, the value in $? would not have the
         top bit set ("$? & 128") even if the child core dumped.

     o   Under some circumstances, $^R could incorrectly become
         undefined [RT #57042].

     o   In the XS API, various hash functions, when passed a
         pre-computed hash where the key is UTF-8, might result
         in an incorrect lookup.

     o   XS code including XSUB.h before perl.h gave a compile-
         time error [RT #57176].

     o   "$object->isa('Foo')" would report false if the package
         "Foo" didn't exist, even if the object's @ISA contained

     o   Various bugs in the new-to 5.10.0 mro code, triggered by
         manipulating @ISA, have been found and fixed.

     o   Bitwise operations on references could crash the
         interpreter, e.g.  "$x=\$y; $x |= "foo"" [RT #54956].

     o   Patterns including alternation might be sensitive to the
         internal UTF-8 representation, e.g.

             my $byte = chr(192);
             my $utf8 = chr(192); utf8::upgrade($utf8);
             $utf8 =~ /$byte|X}/i;       # failed in 5.10.0

     o   Within UTF8-encoded Perl source files (i.e. where "use
         utf8" is in effect), double-quoted literal strings could
         be corrupted where a "\xNN", "\0NNN" or "\N{}" is
         followed by a literal character with ordinal value

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         greater than 255 [RT #59908].

     o   "B::Deparse" failed to correctly deparse various
         constructs: "readpipe STRING" [RT #62428],
         "CORE::require(STRING)" [RT #62488], "sub foo(_)" [RT

     o   Using "setpgrp" with no arguments could corrupt the perl

     o   The block form of "eval" is now specifically trappable
         by "Safe" and "ops". Previously it was erroneously
         treated like string "eval".

     o   In 5.10.0, the two characters "[~" were sometimes parsed
         as the smart match operator ("~~") [RT #63854].

     o   In 5.10.0, the "*" quantifier in patterns was sometimes
         treated as "{0,32767}" [RT #60034, #60464]. For example,
         this match would fail:

             ("ab" x 32768) =~ /^(ab)*$/

     o   "shmget" was limited to a 32 bit segment size on a 64
         bit OS [RT #63924].

     o   Using "next" or "last" to exit a "given" block no longer
         produces a spurious warning like the following:

             Exiting given via last at line 123

     o   Assigning a format to a glob could corrupt the format;

              *bar=*foo{FORMAT}; # foo format now bad

     o   Attempting to coerce a typeglob to a string or number
         could cause an assertion failure. The correct error
         message is now generated, "Can't coerce GLOB to $type".

     o   Under "use filetest 'access'", "-x" was using the wrong
         access mode. This has been fixed [RT #49003].

     o   "length" on a tied scalar that returned a Unicode value
         would not be correct the first time. This has been

     o   Using an array "tie" inside in array "tie" could SEGV.
         This has been fixed. [RT #51636]

     o   A race condition inside "PerlIOStdio_close()" has been
         identified and fixed. This used to cause various

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         threading issues, including SEGVs.

     o   In "unpack", the use of "()" groups in scalar context
         was internally placing a list on the interpreter's
         stack, which manifested in various ways, including
         SEGVs. This is now fixed [RT #50256].

     o   Magic was called twice in "substr", "\&$x", "tie $x, $m"
         and "chop".  These have all been fixed.

     o   A 5.10.0 optimisation to clear the temporary stack
         within the implicit loop of "s///ge" has been reverted,
         as it turned out to be the cause of obscure bugs in
         seemingly unrelated parts of the interpreter [commit

     o   The line numbers for warnings inside "elsif" are now

     o   The ".." operator now works correctly with ranges whose
         ends are at or close to the values of the smallest and
         largest integers.

     o   "binmode STDIN, ':raw'" could lead to segmentation
         faults on some platforms.  This has been fixed [RT

     o   An off-by-one error meant that "index $str, ..." was
         effectively being executed as "index "$str\0", ...".
         This has been fixed [RT #53746].

     o   Various leaks associated with named captures in regexes
         have been fixed [RT #57024].

     o   A weak reference to a hash would leak. This was
         affecting "DBI" [RT #56908].

     o   Using (?|) in a regex could cause a segfault [RT

     o   Use of a UTF-8 "tr//" within a closure could cause a
         segfault [RT #61520].

     o   Calling "Perl_sv_chop()" or otherwise upgrading an SV
         could result in an unaligned 64-bit access on the SPARC
         architecture [RT #60574].

     o   In the 5.10.0 release, "inc_version_list" would
         incorrectly list "5.10.*" after "5.8.*"; this affected
         the @INC search order [RT #67628].

     o   In 5.10.0, "pack "a*", $tainted_value" returned a non-

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         tainted value [RT #52552].

     o   In 5.10.0, "printf" and "sprintf" could produce the
         fatal error "panic: utf8_mg_pos_cache_update" when
         printing UTF-8 strings [RT #62666].

     o   In the 5.10.0 release, a dynamically created "AUTOLOAD"
         method might be missed (method cache issue) [RT

     o   In the 5.10.0 release, a combination of "use feature"
         and "//ee" could cause a memory leak [RT #63110].

     o   "-C" on the shebang ("#!") line is once more permitted
         if it is also specified on the command line. "-C" on the
         shebang line used to be a silent no-op if it was not
         also on the command line, so perl 5.10.0 disallowed it,
         which broke some scripts. Now perl checks whether it is
         also on the command line and only dies if it is not [RT

     o   In 5.10.0, certain types of re-entrant regular
         expression could crash, or cause the following assertion
         failure [RT #60508]:

             Assertion rx->sublen >= (s - rx->subbeg) + i failed

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

     o   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
         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
     Tenon MachTen

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

         o   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.

         o   Hints changes mean that AIX 4.2 should work again.

         o   Perl now supports IPv6 on Cygwin 1.7 and newer.

         o   On Cygwin we now strip the last number from the DLL.
             This has been the behaviour in the build
             for years. The hints files have been updated.

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

         o   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
         o   Fix thread library selection [perl #69686]

         o   The hints files now identify the correct threading
             libraries on FreeBSD 7 and later.

         o   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.

         o   Hints now supports versions 5.*.

         o   "-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; before the only
             way to turn it off was by saying no in answer to the
             interactive question.

         o   The default pipe buffer size on VMS has been updated

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             to 8192 on 64-bit systems.

         o   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.

         o   VMS now supports "getgrgid".

         o   Many improvements and cleanups have been made to the
             VMS file name handling and conversion code.

         o   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.

         o   "File::Copy" now detects Unix compatibility mode on

     Stratus VOS
         o   Various changes from Stratus have been merged in.

         o   There is now support for Symbian S60 3.2 SDK and S60
             5.0 SDK.

         o   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.

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

         o   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.

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         o   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.

         o   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.

         o   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.

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

         o   select() now supports all empty "fd_set"s more

         o   '.\foo' and '..\foo'  were treated differently than
             './foo' and '../foo' by "do" and "require" [RT

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

         o   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.

     o   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

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     o   "List::Util::first" misbehaves in the presence of a
         lexical $_ (typically introduced by "my $_" or
         implicitly by "given"). The variable which gets set for
         each iteration is the package variable $_, not the
         lexical $_ [RT #67694].

         A similar issue may occur in other modules that provide
         functions which take a block as their first argument,

             foo { ... $_ ...} list

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

     o   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].

     o   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.

     o   This one is actually a change introduced in 5.10.0, but
         it was missed from that release's perldelta, so it is
         mentioned here instead.

         A bugfix related to the handling of the "/m" modifier
         and "qr" resulted in a change of behaviour between 5.8.x
         and 5.10.0:

             # matches in 5.8.x, doesn't match in 5.10.0
             $re = qr/^bar/; "foo\nbar" =~ /$re/m;

     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, var Arnfjoer` Bjarmason, Alan

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     Grover, Alexandr Ciornii, Alex Davies, Alex Vandiver,
     Andreas Koenig, Andrew Rodland,, 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

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     complete list of all of Perl's historical contributors,
     please see the "AUTHORS" file in the Perl 5.12.0

     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
     <>. There may also be information
     at <>, 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 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 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 attributes(5) for descriptions of the following

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     |Availability   | runtime/perl-512 |
     |Stability      | Uncommitted      |
     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.

     <> for a list of issues
     found after this release, as well as a list of CPAN modules
     known to be incompatible with this release.

     This software was built from source available at  The original
     community source was downloaded from

     Further information about this software can be found on the
     open source community website at

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