perl5140delta - what is new for perl v5.14.0


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

   If you are upgrading from an earlier release such as 5.10.0, first read
   perl5120delta, which describes differences between 5.10.0 and 5.12.0.

   Some of the bug fixes in this release have been backported to
   subsequent releases of 5.12.x.  Those are indicated with the 5.12.x
   version in parentheses.


   As described in perlpolicy, the release of Perl 5.14.0 marks the
   official end of support for Perl 5.10.  Users of Perl 5.10 or earlier
   should consider upgrading to a more recent release of Perl.

Core Enhancements

   Unicode Version 6.0 is now supported (mostly)

   Perl comes with the Unicode 6.0 data base updated with Corrigendum #8
   <>, with one exception
   noted below.  See <> for
   details on the new release.  Perl does not support any Unicode
   provisional properties, including the new ones for this release.

   Unicode 6.0 has chosen to use the name "BELL" for the character at
   U+1F514, which is a symbol that looks like a bell, and is used in
   Japanese cell phones.  This conflicts with the long-standing Perl usage
   of having "BELL" mean the ASCII "BEL" character, U+0007.  In Perl 5.14,
   "\N{BELL}" continues to mean U+0007, but its use generates a
   deprecation warning message unless such warnings are turned off.  The
   new name for U+0007 in Perl is "ALERT", which corresponds nicely with
   the existing shorthand sequence for it, "\a".  "\N{BEL}" means U+0007,
   with no warning given.  The character at U+1F514 has no name in 5.14,
   but can be referred to by "\N{U+1F514}".  In Perl 5.16, "\N{BELL}" will
   refer to U+1F514; all code that uses "\N{BELL}" should be converted to
   use "\N{ALERT}", "\N{BEL}", or "\a" before upgrading.

   Full functionality for "use feature 'unicode_strings'"

   This release provides full functionality for "use feature
   'unicode_strings'".  Under its scope, all string operations executed
   and regular expressions compiled (even if executed outside its scope)
   have Unicode semantics.  See "the 'unicode_strings' feature" in
   feature.  However, see "Inverted bracketed character classes and multi-
   character folds", below.

   This feature avoids most forms of the "Unicode Bug" (see "The "Unicode
   Bug"" in perlunicode for details).  If there is any possibility that
   your code will process Unicode strings, you are strongly encouraged to
   use this subpragma to avoid nasty surprises.

   "\N{NAME}" and "charnames" enhancements

   *   "\N{NAME}" and "charnames::vianame" now know about the abbreviated
       character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ,
       etc.; all customary abbreviations for the C0 and C1 control
       characters (such as ACK, BEL, CAN, etc.); and a few new variants of
       some C1 full names that are in common usage.

   *   Unicode has several named character sequences, in which particular
       sequences of code points are given names.  "\N{NAME}" now
       recognizes these.

   *   "\N{NAME}", "charnames::vianame", and "charnames::viacode" now know
       about every character in Unicode.  In earlier releases of Perl,
       they didn't know about the Hangul syllables nor several CJK
       (Chinese/Japanese/Korean) characters.

   *   It is now possible to override Perl's abbreviations with your own
       custom aliases.

   *   You can now create a custom alias of the ordinal of a character,
       known by "\N{NAME}", "charnames::vianame()", and
       "charnames::viacode()".  Previously, aliases had to be to official
       Unicode character names.  This made it impossible to create an
       alias for unnamed code points, such as those reserved for private

   *   The new function charnames::string_vianame() is a run-time version
       of "\N{NAME}}", returning the string of characters whose Unicode
       name is its parameter.  It can handle Unicode named character
       sequences, whereas the pre-existing charnames::vianame() cannot, as
       the latter returns a single code point.

   See charnames for details on all these changes.

   New warnings categories for problematic (non-)Unicode code points.

   Three new warnings subcategories of "utf8" have been added.  These
   allow you to turn off some "utf8" warnings, while allowing other
   warnings to remain on.  The three categories are: "surrogate" when
   UTF-16 surrogates are encountered; "nonchar" when Unicode non-character
   code points are encountered; and "non_unicode" when code points above
   the legal Unicode maximum of 0x10FFFF are encountered.

   Any unsigned value can be encoded as a character

   With this release, Perl is adopting a model that any unsigned value can
   be treated as a code point and encoded internally (as utf8) without
   warnings, not just the code points that are legal in Unicode.  However,
   unless utf8 or the corresponding sub-category (see previous item) of
   lexical warnings have been explicitly turned off, outputting or
   executing a Unicode-defined operation such as upper-casing on such a
   code point generates a warning.  Attempting to input these using strict
   rules (such as with the ":encoding(UTF-8)" layer) will continue to
   fail.  Prior to this release, handling was inconsistent and in places,

   Unicode non-characters, some of which previously were erroneously
   considered illegal in places by Perl, contrary to the Unicode Standard,
   are now always legal internally.  Inputting or outputting them works
   the same as with the non-legal Unicode code points, because the Unicode
   Standard says they are (only) illegal for "open interchange".

   Unicode database files not installed

   The Unicode database files are no longer installed with Perl.  This
   doesn't affect any functionality in Perl and saves significant disk
   space.  If you need these files, you can download them from

   Regular Expressions
   "(?^...)" construct signifies default modifiers

   An ASCII caret "^" immediately following a "(?" in a regular expression
   now means that the subexpression does not inherit surrounding modifiers
   such as "/i", but reverts to the Perl defaults.  Any modifiers
   following the caret override the defaults.

   Stringification of regular expressions now uses this notation.  For
   example, "qr/hlagh/i" would previously be stringified as
   "(?i-xsm:hlagh)", but now it's stringified as "(?^i:hlagh)".

   The main purpose of this change is to allow tests that rely on the
   stringification not to have to change whenever new modifiers are added.
   See "Extended Patterns" in perlre.

   This change is likely to break code that compares stringified regular
   expressions with fixed strings containing "?-xism".

   "/d", "/l", "/u", and "/a" modifiers

   Four new regular expression modifiers have been added.  These are
   mutually exclusive: one only can be turned on at a time.

   *   The "/l" modifier says to compile the regular expression as if it
       were in the scope of "use locale", even if it is not.

   *   The "/u" modifier says to compile the regular expression as if it
       were in the scope of a "use feature 'unicode_strings'" pragma.

   *   The "/d" (default) modifier is used to override any "use locale"
       and "use feature 'unicode_strings'" pragmas in effect at the time
       of compiling the regular expression.

   *   The "/a" regular expression modifier restricts "\s", "\d" and "\w"
       and the POSIX ("[[:posix:]]") character classes to the ASCII range.
       Their complements and "\b" and "\B" are correspondingly affected.
       Otherwise, "/a" behaves like the "/u" modifier, in that case-
       insensitive matching uses Unicode semantics.

       If the "/a" modifier is repeated, then additionally in case-
       insensitive matching, no ASCII character can match a non-ASCII
       character.  For example,

           "k"     =~ /\N{KELVIN SIGN}/ai
           "\xDF" =~ /ss/ai

       match but

           "k"    =~ /\N{KELVIN SIGN}/aai
           "\xDF" =~ /ss/aai

       do not match.

   See "Modifiers" in perlre for more detail.

   Non-destructive substitution

   The substitution ("s///") and transliteration ("y///") operators now
   support an "/r" option that copies the input variable, carries out the
   substitution on the copy, and returns the result.  The original remains

     my $old = "cat";
     my $new = $old =~ s/cat/dog/r;
     # $old is "cat" and $new is "dog"

   This is particularly useful with "map".  See perlop for more examples.

   Re-entrant regular expression engine

   It is now safe to use regular expressions within "(?{...})" and
   "(??{...})" code blocks inside regular expressions.

   These blocks are still experimental, however, and still have problems
   with lexical ("my") variables and abnormal exiting.

   "use re '/flags'"

   The "re" pragma now has the ability to turn on regular expression flags
   till the end of the lexical scope:

       use re "/x";
       "foo" =~ / (.+) /;  # /x implied

   See "'/flags' mode" in re for details.

   \o{...} for octals

   There is a new octal escape sequence, "\o", in doublequote-like
   contexts.  This construct allows large octal ordinals beyond the
   current max of 0777 to be represented.  It also allows you to specify a
   character in octal which can safely be concatenated with other regex
   snippets and which won't be confused with being a backreference to a
   regex capture group.  See "Capture groups" in perlre.

   Add "\p{Titlecase}" as a synonym for "\p{Title}"

   This synonym is added for symmetry with the Unicode property names
   "\p{Uppercase}" and "\p{Lowercase}".

   Regular expression debugging output improvement

   Regular expression debugging output (turned on by "use re 'debug'") now
   uses hexadecimal when escaping non-ASCII characters, instead of octal.

   Return value of "delete $+{...}"

   Custom regular expression engines can now determine the return value of
   "delete" on an entry of "%+" or "%-".

   Syntactical Enhancements
   Array and hash container functions accept references

   Warning: This feature is considered experimental, as the exact
   behaviour may change in a future version of Perl.

   All builtin functions that operate directly on array or hash containers
   now also accept unblessed hard references to arrays or hashes:

     | Traditional syntax         | Terse syntax              |
     | push @$arrayref, @stuff    | push $arrayref, @stuff    |
     | unshift @$arrayref, @stuff | unshift $arrayref, @stuff |
     | pop @$arrayref             | pop $arrayref             |
     | shift @$arrayref           | shift $arrayref           |
     | splice @$arrayref, 0, 2    | splice $arrayref, 0, 2    |
     | keys %$hashref             | keys $hashref             |
     | keys @$arrayref            | keys $arrayref            |
     | values %$hashref           | values $hashref           |
     | values @$arrayref          | values $arrayref          |
     | ($k,$v) = each %$hashref   | ($k,$v) = each $hashref   |
     | ($k,$v) = each @$arrayref  | ($k,$v) = each $arrayref  |

   This allows these builtin functions to act on long dereferencing chains
   or on the return value of subroutines without needing to wrap them in
   "@{}" or "%{}":

     push @{$obj->tags}, $new_tag;  # old way
     push $obj->tags,    $new_tag;  # new way

     for ( keys %{$hoh->{genres}{artists}} ) {...} # old way
     for ( keys $hoh->{genres}{artists}    ) {...} # new way

   Single term prototype

   The "+" prototype is a special alternative to "$" that acts like
   "\[@%]" when given a literal array or hash variable, but will otherwise
   force scalar context on the argument.  See "Prototypes" in perlsub.

   "package" block syntax

   A package declaration can now contain a code block, in which case the
   declaration is in scope inside that block only.  So "package Foo { ...
   }" is precisely equivalent to "{ package Foo; ... }".  It also works
   with a version number in the declaration, as in "package Foo 1.2 { ...
   }", which is its most attractive feature.  See perlfunc.

   Statement labels can appear in more places

   Statement labels can now occur before any type of statement or
   declaration, such as "package".

   Stacked labels

   Multiple statement labels can now appear before a single statement.

   Uppercase X/B allowed in hexadecimal/binary literals

   Literals may now use either upper case "0X..." or "0B..." prefixes, in
   addition to the already supported "0x..." and "0b..."  syntax [perl

   C, Ruby, Python, and PHP already support this syntax, and it makes Perl
   more internally consistent: a round-trip with "eval sprintf "%#X",
   0x10" now returns 16, just like "eval sprintf "%#x", 0x10".

   Overridable tie functions

   "tie", "tied" and "untie" can now be overridden [perl #75902].

   Exception Handling
   To make them more reliable and consistent, several changes have been
   made to how "die", "warn", and $@ behave.

   *   When an exception is thrown inside an "eval", the exception is no
       longer at risk of being clobbered by destructor code running during
       unwinding.  Previously, the exception was written into $@ early in
       the throwing process, and would be overwritten if "eval" was used
       internally in the destructor for an object that had to be freed
       while exiting from the outer "eval".  Now the exception is written
       into $@ last thing before exiting the outer "eval", so the code
       running immediately thereafter can rely on the value in $@
       correctly corresponding to that "eval".  ($@ is still also set
       before exiting the "eval", for the sake of destructors that rely on

       Likewise, a "local $@" inside an "eval" no longer clobbers any
       exception thrown in its scope.  Previously, the restoration of $@
       upon unwinding would overwrite any exception being thrown.  Now the
       exception gets to the "eval" anyway.  So "local $@" is safe before
       a "die".

       Exceptions thrown from object destructors no longer modify the $@
       of the surrounding context.  (If the surrounding context was
       exception unwinding, this used to be another way to clobber the
       exception being thrown.)  Previously such an exception was
       sometimes emitted as a warning, and then either was string-appended
       to the surrounding $@ or completely replaced the surrounding $@,
       depending on whether that exception and the surrounding $@ were
       strings or objects.  Now, an exception in this situation is always
       emitted as a warning, leaving the surrounding $@ untouched.  In
       addition to object destructors, this also affects any function call
       run by XS code using the "G_KEEPERR" flag.

   *   Warnings for "warn" can now be objects in the same way as
       exceptions for "die".  If an object-based warning gets the default
       handling of writing to standard error, it is stringified as before
       with the filename and line number appended.  But a $SIG{__WARN__}
       handler now receives an object-based warning as an object, where
       previously it was passed the result of stringifying the object.

   Other Enhancements
   Assignment to $0 sets the legacy process name with prctl() on Linux

   On Linux the legacy process name is now set with prctl(2), in addition
   to altering the POSIX name via "argv[0]", as Perl has done since
   version 4.000.  Now system utilities that read the legacy process name
   such as ps, top, and killall recognize the name you set when assigning
   to $0.  The string you supply is truncated at 16 bytes; this limitation
   is imposed by Linux.

   srand() now returns the seed

   This allows programs that need to have repeatable results not to have
   to come up with their own seed-generating mechanism.  Instead, they can
   use srand() and stash the return value for future use.  One example is
   a test program with too many combinations to test comprehensively in
   the time available for each run.  It can test a random subset each time
   and, should there be a failure, log the seed used for that run so this
   can later be used to produce the same results.

   printf-like functions understand post-1980 size modifiers

   Perl's printf and sprintf operators, and Perl's internal printf
   replacement function, now understand the C90 size modifiers "hh"
   ("char"), "z" ("size_t"), and "t" ("ptrdiff_t").  Also, when compiled
   with a C99 compiler, Perl now understands the size modifier "j"
   ("intmax_t") (but this is not portable).

   So, for example, on any modern machine, "sprintf("%hhd", 257)" returns

   New global variable "${^GLOBAL_PHASE}"

   A new global variable, "${^GLOBAL_PHASE}", has been added to allow
   introspection of the current phase of the Perl interpreter.  It's
   explained in detail in "${^GLOBAL_PHASE}" in perlvar and in "BEGIN,
   UNITCHECK, CHECK, INIT and END" in perlmod.

   "-d:-foo" calls "Devel::foo::unimport"

   The syntax -d:foo was extended in 5.6.1 to make -d:foo=bar equivalent
   to -MDevel::foo=bar, which expands internally to "use Devel::foo
   'bar'".  Perl now allows prefixing the module name with -, with the
   same semantics as -M; that is:

       Equivalent to -M-Devel::foo: expands to "no Devel::foo" and calls
       "Devel::foo->unimport()" if that method exists.

       Equivalent to -M-Devel::foo=bar: expands to "no Devel::foo 'bar'",
       and calls "Devel::foo->unimport("bar")" if that method exists.

   This is particularly useful for suppressing the default actions of a
   "Devel::*" module's "import" method whilst still loading it for

   Filehandle method calls load IO::File on demand

   When a method call on a filehandle would die because the method cannot
   be resolved and IO::File has not been loaded, Perl now loads IO::File
   via "require" and attempts method resolution again:

     open my $fh, ">", $file;
     $fh->binmode(":raw");     # loads IO::File and succeeds

   This also works for globs like "STDOUT", "STDERR", and "STDIN":


   Because this on-demand load happens only if method resolution fails,
   the legacy approach of manually loading an IO::File parent class for
   partial method support still works as expected:

     use IO::Handle;
     open my $fh, ">", $file;
     $fh->autoflush(1);        # IO::File not loaded

   Improved IPv6 support

   The "Socket" module provides new affordances for IPv6, including
   implementations of the "Socket::getaddrinfo()" and
   "Socket::getnameinfo()" functions, along with related constants and a
   handful of new functions.  See Socket.

   DTrace probes now include package name

   The "DTrace" probes now include an additional argument, "arg3", which
   contains the package the subroutine being entered or left was compiled

   For example, using the following DTrace script:

         printf("%s::%s\n", copyinstr(arg0), copyinstr(arg3));

   and then running:

     $ perl -e 'sub test { }; test'

   "DTrace" will print:


   New C APIs
   See "Internal Changes".


   User-defined regular expression properties
   "User-Defined Character Properties" in perlunicode documented that you
   can create custom properties by defining subroutines whose names begin
   with "In" or "Is".  However, Perl did not actually enforce that naming
   restriction, so "\p{foo::bar}" could call foo::bar() if it existed.
   The documented convention is now enforced.

   Also, Perl no longer allows tainted regular expressions to invoke a
   user-defined property.  It simply dies instead [perl #82616].

Incompatible Changes

   Perl 5.14.0 is not binary-compatible with any previous stable release.

   In addition to the sections that follow, see "C API Changes".

   Regular Expressions and String Escapes
   Inverted bracketed character classes and multi-character folds

   Some characters match a sequence of two or three characters in "/i"
   regular expression matching under Unicode rules.  One example is "LATIN
   SMALL LETTER SHARP S" which matches the sequence "ss".

    'ss' =~ /\A[\N{LATIN SMALL LETTER SHARP S}]\z/i  # Matches

   This, however, can lead to very counter-intuitive results, especially
   when inverted.  Because of this, Perl 5.14 does not use multi-character
   "/i" matching in inverted character classes.

    'ss' =~ /\A[^\N{LATIN SMALL LETTER SHARP S}]+\z/i  # ???

   This should match any sequences of characters that aren't the "SHARP S"
   nor what "SHARP S" matches under "/i".  "s" isn't "SHARP S", but
   Unicode says that "ss" is what "SHARP S" matches under "/i".  So which
   one "wins"? Do you fail the match because the string has "ss" or accept
   it because it has an "s" followed by another "s"?

   Earlier releases of Perl did allow this multi-character matching, but
   due to bugs, it mostly did not work.


   In certain circumstances, "\400"-"\777" in regexes have behaved
   differently than they behave in all other doublequote-like contexts.
   Since 5.10.1, Perl has issued a deprecation warning when this happens.
   Now, these literals behave the same in all doublequote-like contexts,
   namely to be equivalent to "\x{100}"-"\x{1FF}", with no deprecation

   Use of "\400"-"\777" in the command-line option -0 retain their
   conventional meaning.  They slurp whole input files; previously, this
   was documented only for -0777.

   Because of various ambiguities, you should use the new "\o{...}"
   construct to represent characters in octal instead.

   Most "\p{}" properties are now immune to case-insensitive matching

   For most Unicode properties, it doesn't make sense to have them match
   differently under "/i" case-insensitive matching.  Doing so can lead to
   unexpected results and potential security holes.  For example


   could previously match non-ASCII characters because of the Unicode
   matching rules (although there were several bugs with this).  Now
   matching under "/i" gives the same results as non-"/i" matching except
   for those few properties where people have come to expect differences,
   namely the ones where casing is an integral part of their meaning, such
   as "m/\p{Uppercase}/i" and "m/\p{Lowercase}/i", both of which match the
   same code points as matched by "m/\p{Cased}/i".  Details are in
   "Unicode Properties" in perlrecharclass.

   User-defined property handlers that need to match differently under
   "/i" must be changed to read the new boolean parameter passed to them,
   which is non-zero if case-insensitive matching is in effect and 0
   otherwise.  See "User-Defined Character Properties" in perlunicode.

   \p{} implies Unicode semantics

   Specifying a Unicode property in the pattern indicates that the pattern
   is meant for matching according to Unicode rules, the way "\N{NAME}"

   Regular expressions retain their localeness when interpolated

   Regular expressions compiled under "use locale" now retain this when
   interpolated into a new regular expression compiled outside a "use
   locale", and vice-versa.

   Previously, one regular expression interpolated into another inherited
   the localeness of the surrounding regex, losing whatever state it
   originally had.  This is considered a bug fix, but may trip up code
   that has come to rely on the incorrect behaviour.

   Stringification of regexes has changed

   Default regular expression modifiers are now notated using "(?^...)".
   Code relying on the old stringification will fail.  This is so that
   when new modifiers are added, such code won't have to keep changing
   each time this happens, because the stringification will automatically
   incorporate the new modifiers.

   Code that needs to work properly with both old- and new-style regexes
   can avoid the whole issue by using (for perls since 5.9.5; see re):

    use re qw(regexp_pattern);
    my ($pat, $mods) = regexp_pattern($re_ref);

   If the actual stringification is important or older Perls need to be
   supported, you can use something like the following:

       # Accept both old and new-style stringification
       my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? "^" : "-xism";

   And then use $modifiers instead of "-xism".

   Run-time code blocks in regular expressions inherit pragmata

   Code blocks in regular expressions ("(?{...})" and "(??{...})")
   previously did not inherit pragmata (strict, warnings, etc.) if the
   regular expression was compiled at run time as happens in cases like
   these two:

     use re "eval";
     $foo =~ $bar; # when $bar contains (?{...})
     $foo =~ /$bar(?{ $finished = 1 })/;

   This bug has now been fixed, but code that relied on the buggy
   behaviour may need to be fixed to account for the correct behaviour.

   Stashes and Package Variables
   Localised tied hashes and arrays are no longed tied

   In the following:

       tie @a, ...;
               local @a;
               # here, @a is a now a new, untied array
       # here, @a refers again to the old, tied array

   Earlier versions of Perl incorrectly tied the new local array.  This
   has now been fixed.  This fix could however potentially cause a change
   in behaviour of some code.

   Stashes are now always defined

   "defined %Foo::" now always returns true, even when no symbols have yet
   been defined in that package.

   This is a side-effect of removing a special-case kludge in the
   tokeniser, added for 5.10.0, to hide side-effects of changes to the
   internal storage of hashes.  The fix drastically reduces hashes' memory

   Calling defined on a stash has been deprecated since 5.6.0, warned on
   lexicals since 5.6.0, and warned for stashes and other package
   variables since 5.12.0.  "defined %hash" has always exposed an
   implementation detail: emptying a hash by deleting all entries from it
   does not make "defined %hash" false.  Hence "defined %hash" is not
   valid code to determine whether an arbitrary hash is empty.  Instead,
   use the behaviour of an empty %hash always returning false in scalar

   Clearing stashes

   Stash list assignment "%foo:: = ()" used to make the stash temporarily
   anonymous while it was being emptied.  Consequently, any of its
   subroutines referenced elsewhere would become anonymous,  showing up as
   "(unknown)" in "caller".  They now retain their package names such that
   "caller" returns the original sub name if there is still a reference to
   its typeglob and "foo::__ANON__" otherwise [perl #79208].

   Dereferencing typeglobs

   If you assign a typeglob to a scalar variable:

       $glob = *foo;

   the glob that is copied to $glob is marked with a special flag
   indicating that the glob is just a copy.  This allows subsequent
   assignments to $glob to overwrite the glob.  The original glob,
   however, is immutable.

   Some Perl operators did not distinguish between these two types of
   globs.  This would result in strange behaviour in edge cases: "untie
   $scalar" would not untie the scalar if the last thing assigned to it
   was a glob (because it treated it as "untie *$scalar", which unties a
   handle).  Assignment to a glob slot (such as "*$glob = \@some_array")
   would simply assign "\@some_array" to $glob.

   To fix this, the "*{}" operator (including its *foo and *$foo forms)
   has been modified to make a new immutable glob if its operand is a glob
   copy.  This allows operators that make a distinction between globs and
   scalars to be modified to treat only immutable globs as globs.  ("tie",
   "tied" and "untie" have been left as they are for compatibility's sake,
   but will warn.  See "Deprecations".)

   This causes an incompatible change in code that assigns a glob to the
   return value of "*{}" when that operator was passed a glob copy.  Take
   the following code, for instance:

       $glob = *foo;
       *$glob = *bar;

   The *$glob on the second line returns a new immutable glob.  That new
   glob is made an alias to *bar.  Then it is discarded.  So the second
   assignment has no effect.

   See <> for more

   Magic variables outside the main package

   In previous versions of Perl, magic variables like $!, %SIG, etc. would
   "leak" into other packages.  So %foo::SIG could be used to access
   signals, "${"foo::!"}" (with strict mode off) to access C's "errno",

   This was a bug, or an "unintentional" feature, which caused various ill
   effects, such as signal handlers being wiped when modules were loaded,

   This has been fixed (or the feature has been removed, depending on how
   you see it).

   local($_) strips all magic from $_

   local() on scalar variables gives them a new value but keeps all their
   magic intact.  This has proven problematic for the default scalar
   variable $_, where perlsub recommends that any subroutine that assigns
   to $_ should first localize it.  This would throw an exception if $_ is
   aliased to a read-only variable, and could in general have various
   unintentional side-effects.

   Therefore, as an exception to the general rule, local($_) will not only
   assign a new value to $_, but also remove all existing magic from it as

   Parsing of package and variable names

   Parsing the names of packages and package variables has changed:
   multiple adjacent pairs of colons, as in "foo::::bar", are now all
   treated as package separators.

   Regardless of this change, the exact parsing of package separators has
   never been guaranteed and is subject to change in future Perl versions.

   Changes to Syntax or to Perl Operators
   "given" return values

   "given" blocks now return the last evaluated expression, or an empty
   list if the block was exited by "break".  Thus you can now write:

       my $type = do {
        given ($num) {
         break     when undef;
         "integer" when /^[+-]?[0-9]+$/;
         "float"   when /^[+-]?[0-9]+(?:\.[0-9]+)?$/;

   See "Return value" in perlsyn for details.

   Change in parsing of certain prototypes

   Functions declared with the following prototypes now behave correctly
   as unary functions:

     \$ \% \@ \* \&
     ;$ ;*
     ;\$ ;\% etc.

   Due to this bug fix [perl #75904], functions using the "(*)", "(;$)"
   and "(;*)" prototypes are parsed with higher precedence than before.
   So in the following example:

     sub foo(;$);
     foo $a < $b;

   the second line is now parsed correctly as "foo($a) < $b", rather than
   "foo($a < $b)".  This happens when one of these operators is used in an
   unparenthesised argument:

     < > <= >= lt gt le ge
     == != <=> eq ne cmp ~~
     | ^
     || //
     .. ...
     = += -= *= etc.
     , =>

   Smart-matching against array slices

   Previously, the following code resulted in a successful match:

       my @a = qw(a y0 z);
       my @b = qw(a x0 z);
       @a[0 .. $#b] ~~ @b;

   This odd behaviour has now been fixed [perl #77468].

   Negation treats strings differently from before

   The unary negation operator, "-", now treats strings that look like
   numbers as numbers [perl #57706].

   Negative zero

   Negative zero (-0.0), when converted to a string, now becomes "0" on
   all platforms.  It used to become "-0" on some, but "0" on others.

   If you still need to determine whether a zero is negative, use
   "sprintf("%g", $zero) =~ /^-/" or the Data::Float module on CPAN.

   ":=" is now a syntax error

   Previously "my $pi := 4" was exactly equivalent to "my $pi : = 4", with
   the ":" being treated as the start of an attribute list, ending before
   the "=".  The use of ":=" to mean ": =" was deprecated in 5.12.0, and
   is now a syntax error.  This allows future use of ":=" as a new token.

   Outside the core's tests for it, we find no Perl 5 code on CPAN using
   this construction, so we believe that this change will have little
   impact on real-world codebases.

   If it is absolutely necessary to have empty attribute lists (for
   example, because of a code generator), simply avoid the error by adding
   a space before the "=".

   Change in the parsing of identifiers

   Characters outside the Unicode "XIDStart" set are no longer allowed at
   the beginning of an identifier.  This means that certain accents and
   marks that normally follow an alphabetic character may no longer be the
   first character of an identifier.

   Threads and Processes
   Directory handles not copied to threads

   On systems other than Windows that do not have a "fchdir" function,
   newly-created threads no longer inherit directory handles from their
   parent threads.  Such programs would usually have crashed anyway [perl

   "close" on shared pipes

   To avoid deadlocks, the "close" function no longer waits for the child
   process to exit if the underlying file descriptor is still in use by
   another thread.  It returns true in such cases.

   fork() emulation will not wait for signalled children

   On Windows parent processes would not terminate until all forked
   children had terminated first.  However, "kill("KILL", ...)" is
   inherently unstable on pseudo-processes, and "kill("TERM", ...)"  might
   not get delivered if the child is blocked in a system call.

   To avoid the deadlock and still provide a safe mechanism to terminate
   the hosting process, Perl now no longer waits for children that have
   been sent a SIGTERM signal.  It is up to the parent process to
   waitpid() for these children if child-cleanup processing must be
   allowed to finish.  However, it is also then the responsibility of the
   parent to avoid the deadlock by making sure the child process can't be
   blocked on I/O.

   See perlfork for more information about the fork() emulation on

   Naming fixes in Policy_sh.SH may invalidate

   Several long-standing typos and naming confusions in Policy_sh.SH have
   been fixed, standardizing on the variable names used in

   This will change the behaviour of if you happen to have been
   accidentally relying on its incorrect behaviour.

   Perl source code is read in text mode on Windows

   Perl scripts used to be read in binary mode on Windows for the benefit
   of the ByteLoader module (which is no longer part of core Perl).  This
   had the side-effect of breaking various operations on the "DATA"
   filehandle, including seek()/tell(), and even simply reading from
   "DATA" after filehandles have been flushed by a call to system(),
   backticks, fork() etc.

   The default build options for Windows have been changed to read Perl
   source code on Windows in text mode now.  ByteLoader will (hopefully)
   be updated on CPAN to automatically handle this situation [perl


   See also "Deprecated C APIs".

   Omitting a space between a regular expression and subsequent word
   Omitting the space between a regular expression operator or its
   modifiers and the following word is deprecated.  For example,
   "m/foo/sand $bar" is for now still parsed as "m/foo/s and $bar", but
   will now issue a warning.

   The backslash-c construct was designed as a way of specifying non-
   printable characters, but there were no restrictions (on ASCII
   platforms) on what the character following the "c" could be.  Now, a
   deprecation warning is raised if that character isn't an ASCII
   character.  Also, a deprecation warning is raised for "\c{" (which is
   the same as simply saying ";").

   "\b{" and "\B{"
   In regular expressions, a literal "{" immediately following a "\b" (not
   in a bracketed character class) or a "\B{" is now deprecated to allow
   for its future use by Perl itself.

   Perl 4-era .pl libraries
   Perl bundles a handful of library files that predate Perl 5.  This
   bundling is now deprecated for most of these files, which are now
   available from CPAN.  The affected files now warn when run, if they
   were installed as part of the core.

   This is a mandatory warning, not obeying -X or lexical warning bits.
   The warning is modelled on that supplied by for
   deprecated-in-core .pm libraries.  It points to the specific CPAN
   distribution that contains the .pl libraries.  The CPAN versions, of
   course, do not generate the warning.

   List assignment to $[
   Assignment to $[ was deprecated and started to give warnings in Perl
   version 5.12.0.  This version of Perl (5.14) now also emits a warning
   when assigning to $[ in list context.  This fixes an oversight in

   Use of qw(...) as parentheses
   Historically the parser fooled itself into thinking that "qw(...)"
   literals were always enclosed in parentheses, and as a result you could
   sometimes omit parentheses around them:

       for $x qw(a b c) { ... }

   The parser no longer lies to itself in this way.  Wrap the list literal
   in parentheses like this:

       for $x (qw(a b c)) { ... }

   This is being deprecated because the parentheses in "for $i (1,2,3) {
   ... }" are not part of expression syntax.  They are part of the
   statement syntax, with the "for" statement wanting literal parentheses.
   The synthetic parentheses that a "qw" expression acquired were only
   intended to be treated as part of expression syntax.

   Note that this does not change the behaviour of cases like:

       use POSIX qw(setlocale localeconv);
       our @EXPORT = qw(foo bar baz);

   where parentheses were never required around the expression.

   This is because Unicode is using that name for a different character.
   See "Unicode Version 6.0 is now supported (mostly)" for more

   "?PATTERN?" (without the initial "m") has been deprecated and now
   produces a warning.  This is to allow future use of "?" in new
   operators.  The match-once functionality is still available as

   Tie functions on scalars holding typeglobs
   Calling a tie function ("tie", "tied", "untie") with a scalar argument
   acts on a filehandle if the scalar happens to hold a typeglob.

   This is a long-standing bug that will be removed in Perl 5.16, as there
   is currently no way to tie the scalar itself when it holds a typeglob,
   and no way to untie a scalar that has had a typeglob assigned to it.

   Now there is a deprecation warning whenever a tie function is used on a
   handle without an explicit "*".

   User-defined case-mapping
   This feature is being deprecated due to its many issues, as documented
   in "User-Defined Case Mappings (for serious hackers only)" in
   perlunicode.  This feature will be removed in Perl 5.16.  Instead use
   the CPAN module Unicode::Casing, which provides improved functionality.

   Deprecated modules
   The following module will be removed from the core distribution in a
   future release, and should be installed from CPAN instead.
   Distributions on CPAN that require this should add it to their
   prerequisites.  The core version of these module now issues a
   deprecation warning.

   If you ship a packaged version of Perl, either alone or as part of a
   larger system, then you should carefully consider the repercussions of
   core module deprecations.  You may want to consider shipping your
   default build of Perl with a package for the deprecated module that
   installs 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 module in
   question from CPAN.  To install the latest version of it by role rather
   than by name, just install "Task::Deprecations::5_14".

       We strongly recommend that you install and use Devel::NYTProf
       instead of Devel::DProf, as Devel::NYTProf offers significantly
       improved profiling and reporting.

Performance Enhancements

   "Safe signals" optimisation
   Signal dispatch has been moved from the runloop into control ops.  This
   should give a few percent speed increase, and eliminates nearly all the
   speed penalty caused by the introduction of "safe signals" in 5.8.0.
   Signals should still be dispatched within the same statement as they
   were previously.  If this does not happen, or if you find it possible
   to create uninterruptible loops, this is a bug, and reports are
   encouraged of how to recreate such issues.

   Optimisation of shift() and pop() calls without arguments
   Two fewer OPs are used for shift() and pop() calls with no argument
   (with implicit @_).  This change makes shift() 5% faster than "shift
   @_" on non-threaded perls, and 25% faster on threaded ones.

   Optimisation of regexp engine string comparison work
   The "foldEQ_utf8" API function for case-insensitive comparison of
   strings (which is used heavily by the regexp engine) was substantially
   refactored and optimised -- and its documentation much improved as a
   free bonus.

   Regular expression compilation speed-up
   Compiling regular expressions has been made faster when upgrading the
   regex to utf8 is necessary but this isn't known when the compilation

   String appending is 100 times faster
   When doing a lot of string appending, perls built to use the system's
   "malloc" could end up allocating a lot more memory than needed in a
   inefficient way.

   "sv_grow", the function used to allocate more memory if necessary when
   appending to a string, has been taught to round up the memory it
   requests to a certain geometric progression, making it much faster on
   certain platforms and configurations.  On Win32, it's now about 100
   times faster.

   Eliminate "PL_*" accessor functions under ithreads
   When "MULTIPLICITY" was first developed, and interpreter state moved
   into an interpreter struct, thread- and interpreter-local "PL_*"
   variables were defined as macros that called accessor functions
   (returning the address of the value) outside the Perl core.  The intent
   was to allow members within the interpreter struct to change size
   without breaking binary compatibility, so that bug fixes could be
   merged to a maintenance branch that necessitated such a size change.
   This mechanism was redundant and penalised well-behaved code.  It has
   been removed.

   Freeing weak references
   When there are many weak references to an object, freeing that object
   can under some circumstances take O(N*N) time to free, where N is the
   number of references.  The circumstances in which this can happen have
   been reduced [perl #75254]

   Lexical array and hash assignments
   An earlier optimisation to speed up "my @array = ..." and "my %hash =
   ..." assignments caused a bug and was disabled in Perl 5.12.0.

   Now we have found another way to speed up these assignments [perl

   @_ uses less memory
   Previously, @_ was allocated for every subroutine at compile time with
   enough space for four entries.  Now this allocation is done on demand
   when the subroutine is called [perl #72416].

   Size optimisations to SV and HV structures
   "xhv_fill" has been eliminated from "struct xpvhv", saving 1 IV per
   hash and on some systems will cause "struct xpvhv" to become cache-
   aligned.  To avoid this memory saving causing a slowdown elsewhere,
   boolean use of "HvFILL" now calls "HvTOTALKEYS" instead (which is
   equivalent), so while the fill data when actually required are now
   calculated on demand, cases when this needs to be done should be rare.

   The order of structure elements in SV bodies has changed.  Effectively,
   the NV slot has swapped location with STASH and MAGIC.  As all access
   to SV members is via macros, this should be completely transparent.
   This change allows the space saving for PVHVs documented above, and may
   reduce the memory allocation needed for PVIVs on some architectures.

   "XPV", "XPVIV", and "XPVNV" now allocate only the parts of the "SV"
   body they actually use, saving some space.

   Scalars containing regular expressions now allocate only the part of
   the "SV" body they actually use, saving some space.

   Memory consumption improvements to Exporter
   The @EXPORT_FAIL AV is no longer created unless needed, hence neither
   is the typeglob backing it.  This saves about 200 bytes for every
   package that uses Exporter but doesn't use this functionality.

   Memory savings for weak references
   For weak references, the common case of just a single weak reference
   per referent has been optimised to reduce the storage required.  In
   this case it saves the equivalent of one small Perl array per referent.

   "%+" and "%-" use less memory
   The bulk of the "Tie::Hash::NamedCapture" module used to be in the Perl
   core.  It has now been moved to an XS module to reduce overhead for
   programs that do not use "%+" or "%-".

   Multiple small improvements to threads
   The internal structures of threading now make fewer API calls and fewer
   allocations, resulting in noticeably smaller object code.
   Additionally, many thread context checks have been deferred so they're
   done only as needed (although this is only possible for non-debugging

   Adjacent pairs of nextstate opcodes are now optimized away
   Previously, in code such as

       use constant DEBUG => 0;

       sub GAK {
           warn if DEBUG;
           print "stuff\n";

   the ops for "warn if DEBUG" would be folded to a "null" op
   ("ex-const"), but the "nextstate" op would remain, resulting in a
   runtime op dispatch of "nextstate", "nextstate", etc.

   The execution of a sequence of "nextstate" ops is indistinguishable
   from just the last "nextstate" op so the peephole optimizer now
   eliminates the first of a pair of "nextstate" ops except when the first
   carries a label, since labels must not be eliminated by the optimizer,
   and label usage isn't conclusively known at compile time.

Modules and Pragmata

   New Modules and Pragmata
   *   CPAN::Meta::YAML 0.003 has been added as a dual-life module.  It
       supports a subset of YAML sufficient for reading and writing
       META.yml and MYMETA.yml files included with CPAN distributions or
       generated by the module installation toolchain.  It should not be
       used for any other general YAML parsing or generation task.

   *   CPAN::Meta version 2.110440 has been added as a dual-life module.
       It provides a standard library to read, interpret and write CPAN
       distribution metadata files (like META.json and META.yml) that
       describe a distribution, its contents, and the requirements for
       building it and installing it.  The latest CPAN distribution
       metadata specification is included as CPAN::Meta::Spec and notes on
       changes in the specification over time are given in

   *   HTTP::Tiny 0.012 has been added as a dual-life module.  It is a
       very small, simple HTTP/1.1 client designed for simple GET requests
       and file mirroring.  It has been added so that and CPANPLUS
       can "bootstrap" HTTP access to CPAN using pure Perl without relying
       on external binaries like curl(1) or wget(1).

   *   JSON::PP 2.27105 has been added as a dual-life module to allow CPAN
       clients to read META.json files in CPAN distributions.

   *   Module::Metadata 1.000004 has been added as a dual-life module.  It
       gathers package and POD information from Perl module files.  It is
       a standalone module based on Module::Build::ModuleInfo for use by
       other module installation toolchain components.
       Module::Build::ModuleInfo has been deprecated in favor of this
       module instead.

   *   Perl::OSType 1.002 has been added as a dual-life module.  It maps
       Perl operating system names (like "dragonfly" or "MSWin32") to more
       generic types with standardized names (like "Unix" or "Windows").
       It has been refactored out of Module::Build and ExtUtils::CBuilder
       and consolidates such mappings into a single location for easier

   *   The following modules were added by the Unicode::Collate upgrade.
       See below for details.







   *   Version::Requirements version 0.101020 has been added as a dual-
       life module.  It provides a standard library to model and
       manipulates module prerequisites and version constraints defined in

   Updated Modules and Pragma
   *   attributes has been upgraded from version 0.12 to 0.14.

   *   Archive::Extract has been upgraded from version 0.38 to 0.48.

       Updates since 0.38 include: a safe print method that guards
       Archive::Extract from changes to "$\"; a fix to the tests when run
       in core Perl; support for TZ files; a modification for the lzma
       logic to favour IO::Uncompress::Unlzma; and a fix for an issue with
       NetBSD-current and its new unzip(1) executable.

   *   Archive::Tar has been upgraded from version 1.54 to 1.76.

       Important changes since 1.54 include the following:

       *   Compatibility with busybox implementations of tar(1).

       *   A fix so that write() and create_archive() close only
           filehandles they themselves opened.

       *   A bug was fixed regarding the exit code of extract_archive.

       *   The ptar(1) utility has a new option to allow safe creation of
           tarballs without world-writable files on Windows, allowing
           those archives to be uploaded to CPAN.

       *   A new ptargrep(1) utility for using regular expressions against
           the contents of files in a tar archive.

       *   pax extended headers are now skipped.

   *   Attribute::Handlers has been upgraded from version 0.87 to 0.89.

   *   autodie has been upgraded from version 2.06_01 to 2.1001.

   *   AutoLoader has been upgraded from version 5.70 to 5.71.

   *   The B module has been upgraded from version 1.23 to 1.29.

       It no longer crashes when taking apart a "y///" containing
       characters outside the octet range or compiled in a "use utf8"

       The size of the shared object has been reduced by about 40%, with
       no reduction in functionality.

   *   B::Concise has been upgraded from version 0.78 to 0.83.

       B::Concise marks rv2sv(), rv2av(), and rv2hv() ops with the new
       "OPpDEREF" flag as "DREFed".

       It no longer produces mangled output with the -tree option [perl

   *   B::Debug has been upgraded from version 1.12 to 1.16.

   *   B::Deparse has been upgraded from version 0.96 to 1.03.

       The deparsing of a "nextstate" op has changed when it has both a
       change of package relative to the previous nextstate, or a change
       of "%^H" or other state and a label.  The label was previously
       emitted first, but is now emitted last (5.12.1).

       The "no 5.13.2" or similar form is now correctly handled by
       B::Deparse (5.12.3).

       B::Deparse now properly handles the code that applies a conditional
       pattern match against implicit $_ as it was fixed in [perl #20444].

       Deparsing of "our" followed by a variable with funny characters (as
       permitted under the "use utf8" pragma) has also been fixed [perl

   *   B::Lint has been upgraded from version 1.11_01 to 1.13.

   *   base has been upgraded from version 2.15 to 2.16.

   *   Benchmark has been upgraded from version 1.11 to 1.12.

   *   bignum has been upgraded from version 0.23 to 0.27.

   *   Carp has been upgraded from version 1.15 to 1.20.

       Carp now detects incomplete caller() overrides and avoids using
       bogus @DB::args.  To provide backtraces, Carp relies on particular
       behaviour of the caller() builtin.  Carp now detects if other code
       has overridden this with an incomplete implementation, and modifies
       its backtrace accordingly.  Previously incomplete overrides would
       cause incorrect values in backtraces (best case), or obscure fatal
       errors (worst case).

       This fixes certain cases of "Bizarre copy of ARRAY" caused by
       modules overriding caller() incorrectly (5.12.2).

       It now also avoids using regular expressions that cause Perl to
       load its Unicode tables, so as to avoid the "BEGIN not safe after
       errors" error that ensue if there has been a syntax error [perl

   *   CGI has been upgraded from version 3.48 to 3.52.

       This provides the following security fixes: the MIME boundary in
       multipart_init() is now random and the handling of newlines
       embedded in header values has been improved.

   *   Compress::Raw::Bzip2 has been upgraded from version 2.024 to 2.033.

       It has been updated to use bzip2(1) 1.0.6.

   *   Compress::Raw::Zlib has been upgraded from version 2.024 to 2.033.

   *   constant has been upgraded from version 1.20 to 1.21.

       Unicode constants work once more.  They have been broken since Perl
       5.10.0 [CPAN RT #67525].

   *   CPAN has been upgraded from version 1.94_56 to 1.9600.

       Major highlights:

       *   much less configuration dialog hassle

       *   support for META/MYMETA.json

       *   support for local::lib

       *   support for HTTP::Tiny to reduce the dependency on FTP sites

       *   automatic mirror selection

       *   iron out all known bugs in configure_requires

       *   support for distributions compressed with bzip2(1)

       *   allow Foo/ on the command line to mean "Foo::Bar"

   *   CPANPLUS has been upgraded from version 0.90 to 0.9103.

       A change to cpanp-run-perl resolves RT #55964
       <> and RT #57106
       <>, both of
       which related to failures to install distributions that use
       "Module::Install::DSL" (5.12.2).

       A dependency on Config was not recognised as a core module
       dependency.  This has been fixed.

       CPANPLUS now includes support for META.json and MYMETA.json.

   *   CPANPLUS::Dist::Build has been upgraded from version 0.46 to 0.54.

   *   Data::Dumper has been upgraded from version 2.125 to 2.130_02.

       The indentation used to be off when $Data::Dumper::Terse was set.
       This has been fixed [perl #73604].

       This upgrade also fixes a crash when using custom sort functions
       that might cause the stack to change [perl #74170].

       Dumpxs no longer crashes with globs returned by *$io_ref [perl

   *   DB_File has been upgraded from version 1.820 to 1.821.

   *   DBM_Filter has been upgraded from version 0.03 to 0.04.

   *   Devel::DProf has been upgraded from version 20080331.00 to

       Merely loading Devel::DProf now no longer triggers profiling to
       start.  Both "use Devel::DProf" and "perl -d:DProf ..." behave as
       before and start the profiler.

       NOTE: Devel::DProf is deprecated and will be removed from a future
       version of Perl.  We strongly recommend that you install and use
       Devel::NYTProf instead, as it offers significantly improved
       profiling and reporting.

   *   Devel::Peek has been upgraded from version 1.04 to 1.07.

   *   Devel::SelfStubber has been upgraded from version 1.03 to 1.05.

   *   diagnostics has been upgraded from version 1.19 to 1.22.

       It now renders pod links slightly better, and has been taught to
       find descriptions for messages that share their descriptions with
       other messages.

   *   Digest::MD5 has been upgraded from version 2.39 to 2.51.

       It is now safe to use this module in combination with threads.

   *   Digest::SHA has been upgraded from version 5.47 to 5.61.

       "shasum" now more closely mimics sha1sum(1)/md5sum(1).

       "addfile" accepts all POSIX filenames.

       New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS
       180-4 [February 2011])

   *   DirHandle has been upgraded from version 1.03 to 1.04.

   *   Dumpvalue has been upgraded from version 1.13 to 1.16.

   *   DynaLoader has been upgraded from version 1.10 to 1.13.

       It fixes a buffer overflow when passed a very long file name.

       It no longer inherits from AutoLoader; hence it no longer produces
       weird error messages for unsuccessful method calls on classes that
       inherit from DynaLoader [perl #84358].

   *   Encode has been upgraded from version 2.39 to 2.42.

       Now, all 66 Unicode non-characters are treated the same way U+FFFF
       has always been treated: in cases when it was disallowed, all 66
       are disallowed, and in cases where it warned, all 66 warn.

   *   Env has been upgraded from version 1.01 to 1.02.

   *   Errno has been upgraded from version 1.11 to 1.13.

       The implementation of Errno has been refactored to use about 55%
       less memory.

       On some platforms with unusual header files, like Win32 gcc(1)
       using "mingw64" headers, some constants that weren't actually error
       numbers have been exposed by Errno.  This has been fixed [perl

   *   Exporter has been upgraded from version 5.64_01 to 5.64_03.

       Exporter no longer overrides $SIG{__WARN__} [perl #74472]

   *   ExtUtils::CBuilder has been upgraded from version 0.27 to 0.280203.

   *   ExtUtils::Command has been upgraded from version 1.16 to 1.17.

   *   ExtUtils::Constant has been upgraded from 0.22 to 0.23.

       The AUTOLOAD helper code generated by
       "ExtUtils::Constant::ProxySubs" can now croak() for missing
       constants, or generate a complete "AUTOLOAD" subroutine in XS,
       allowing simplification of many modules that use it (Fcntl,
       File::Glob, GDBM_File, I18N::Langinfo, POSIX, Socket).

       ExtUtils::Constant::ProxySubs can now optionally push the names of
       all constants onto the package's @EXPORT_OK.

   *   ExtUtils::Install has been upgraded from version 1.55 to 1.56.

   *   ExtUtils::MakeMaker has been upgraded from version 6.56 to 6.57_05.

   *   ExtUtils::Manifest has been upgraded from version 1.57 to 1.58.

   *   ExtUtils::ParseXS has been upgraded from version 2.21 to 2.2210.

   *   Fcntl has been upgraded from version 1.06 to 1.11.

   *   File::Basename has been upgraded from version 2.78 to 2.82.

   *   File::CheckTree has been upgraded from version 4.4 to 4.41.

   *   File::Copy has been upgraded from version 2.17 to 2.21.

   *   File::DosGlob has been upgraded from version 1.01 to 1.04.

       It allows patterns containing literal parentheses: they no longer
       need to be escaped.  On Windows, it no longer adds an extra ./ to
       file names returned when the pattern is a relative glob with a
       drive specification, like C:*.pl [perl #71712].

   *   File::Fetch has been upgraded from version 0.24 to 0.32.

       HTTP::Lite is now supported for the "http" scheme.

       The fetch(1) utility is supported on FreeBSD, NetBSD, and Dragonfly
       BSD for the "http" and "ftp" schemes.

   *   File::Find has been upgraded from version 1.15 to 1.19.

       It improves handling of backslashes on Windows, so that paths like
       C:\dir\/file are no longer generated [perl #71710].

   *   File::Glob has been upgraded from version 1.07 to 1.12.

   *   File::Spec has been upgraded from version 3.31 to 3.33.

       Several portability fixes were made in File::Spec::VMS: a colon is
       now recognized as a delimiter in native filespecs; caret-escaped
       delimiters are recognized for better handling of extended
       filespecs; catpath() returns an empty directory rather than the
       current directory if the input directory name is empty; and
       abs2rel() properly handles Unix-style input (5.12.2).

   *   File::stat has been upgraded from 1.02 to 1.05.

       The "-x" and "-X" file test operators now work correctly when run
       by the superuser.

   *   Filter::Simple has been upgraded from version 0.84 to 0.86.

   *   GDBM_File has been upgraded from 1.10 to 1.14.

       This fixes a memory leak when DBM filters are used.

   *   Hash::Util has been upgraded from 0.07 to 0.11.

       Hash::Util no longer emits spurious "uninitialized" warnings when
       recursively locking hashes that have undefined values [perl

   *   Hash::Util::FieldHash has been upgraded from version 1.04 to 1.09.

   *   I18N::Collate has been upgraded from version 1.01 to 1.02.

   *   I18N::Langinfo has been upgraded from version 0.03 to 0.08.

       langinfo() now defaults to using $_ if there is no argument given,
       just as the documentation has always claimed.

   *   I18N::LangTags has been upgraded from version 0.35 to 0.35_01.

   *   if has been upgraded from version 0.05 to 0.0601.

   *   IO has been upgraded from version 1.25_02 to 1.25_04.

       This version of IO includes a new IO::Select, which now allows
       IO::Handle objects (and objects in derived classes) to be removed
       from an IO::Select set even if the underlying file descriptor is
       closed or invalid.

   *   IPC::Cmd has been upgraded from version 0.54 to 0.70.

       Resolves an issue with splitting Win32 command lines.  An argument
       consisting of the single character "0" used to be omitted (CPAN RT

   *   IPC::Open3 has been upgraded from 1.05 to 1.09.

       open3() now produces an error if the "exec" call fails, allowing
       this condition to be distinguished from a child process that exited
       with a non-zero status [perl #72016].

       The internal xclose() routine now knows how to handle file
       descriptors as documented, so duplicating "STDIN" in a child
       process using its file descriptor now works [perl #76474].

   *   IPC::SysV has been upgraded from version 2.01 to 2.03.

   *   lib has been upgraded from version 0.62 to 0.63.

   *   Locale::Maketext has been upgraded from version 1.14 to 1.19.

       Locale::Maketext now supports external caches.

       This upgrade also fixes an infinite loop in
       "Locale::Maketext::Guts::_compile()" when working with tainted
       values (CPAN RT #40727).

       "->maketext" calls now back up and restore $@ so error messages are
       not suppressed (CPAN RT #34182).

   *   Log::Message has been upgraded from version 0.02 to 0.04.

   *   Log::Message::Simple has been upgraded from version 0.06 to 0.08.

   *   Math::BigInt has been upgraded from version 1.89_01 to 1.994.

       This fixes, among other things, incorrect results when computing
       binomial coefficients [perl #77640].

       It also prevents "sqrt($int)" from crashing under "use bigrat".
       [perl #73534].

   *   Math::BigInt::FastCalc has been upgraded from version 0.19 to 0.28.

   *   Math::BigRat has been upgraded from version 0.24 to 0.26_02.

   *   Memoize has been upgraded from version 1.01_03 to 1.02.

   *   MIME::Base64 has been upgraded from 3.08 to 3.13.

       Includes new functions to calculate the length of encoded and
       decoded base64 strings.

       Now provides encode_base64url() and decode_base64url() functions to
       process the base64 scheme for "URL applications".

   *   Module::Build has been upgraded from version 0.3603 to 0.3800.

       A notable change is the deprecation of several modules.
       Module::Build::Version has been deprecated and Module::Build now
       relies on the version pragma directly.  Module::Build::ModuleInfo
       has been deprecated in favor of a standalone copy called
       Module::Metadata.  Module::Build::YAML has been deprecated in favor
       of CPAN::Meta::YAML.

       Module::Build now also generates META.json and MYMETA.json files in
       accordance with version 2 of the CPAN distribution metadata
       specification, CPAN::Meta::Spec.  The older format META.yml and
       MYMETA.yml files are still generated.

   *   Module::CoreList has been upgraded from version 2.29 to 2.47.

       Besides listing the updated core modules of this release, it also
       stops listing the "Filespec" module.  That module never existed in
       core.  The scripts generating Module::CoreList confused it with
       VMS::Filespec, which actually is a core module as of Perl 5.8.7.

   *   Module::Load has been upgraded from version 0.16 to 0.18.

   *   Module::Load::Conditional has been upgraded from version 0.34 to

   *   The mro pragma has been upgraded from version 1.02 to 1.07.

   *   NDBM_File has been upgraded from version 1.08 to 1.12.

       This fixes a memory leak when DBM filters are used.

   *   Net::Ping has been upgraded from version 2.36 to 2.38.

   *   NEXT has been upgraded from version 0.64 to 0.65.

   *   Object::Accessor has been upgraded from version 0.36 to 0.38.

   *   ODBM_File has been upgraded from version 1.07 to 1.10.

       This fixes a memory leak when DBM filters are used.

   *   Opcode has been upgraded from version 1.15 to 1.18.

   *   The overload pragma has been upgraded from 1.10 to 1.13.

       "overload::Method" can now handle subroutines that are themselves
       blessed into overloaded classes [perl #71998].

       The documentation has greatly improved.  See "Documentation" below.

   *   Params::Check has been upgraded from version 0.26 to 0.28.

   *   The parent pragma has been upgraded from version 0.223 to 0.225.

   *   Parse::CPAN::Meta has been upgraded from version 1.40 to 1.4401.

       The latest Parse::CPAN::Meta can now read YAML and JSON files using
       CPAN::Meta::YAML and JSON::PP, which are now part of the Perl core.

   *   PerlIO::encoding has been upgraded from version 0.12 to 0.14.

   *   PerlIO::scalar has been upgraded from 0.07 to 0.11.

       A read() after a seek() beyond the end of the string no longer
       thinks it has data to read [perl #78716].

   *   PerlIO::via has been upgraded from version 0.09 to 0.11.

   *   Pod::Html has been upgraded from version 1.09 to 1.11.

   *   Pod::LaTeX has been upgraded from version 0.58 to 0.59.

   *   Pod::Perldoc has been upgraded from version 3.15_02 to 3.15_03.

   *   Pod::Simple has been upgraded from version 3.13 to 3.16.

   *   POSIX has been upgraded from 1.19 to 1.24.

       It now includes constants for POSIX signal constants.

   *   The re pragma has been upgraded from version 0.11 to 0.18.

       The "use re '/flags'" subpragma is new.

       The regmust() function used to crash when called on a regular
       expression belonging to a pluggable engine.  Now it croaks instead.

       regmust() no longer leaks memory.

   *   Safe has been upgraded from version 2.25 to 2.29.

       Coderefs returned by reval() and rdo() are now wrapped via
       wrap_code_refs() (5.12.1).

       This fixes a possible infinite loop when looking for coderefs.

       It adds several "version::vxs::*" routines to the default share.

   *   SDBM_File has been upgraded from version 1.06 to 1.09.

   *   SelfLoader has been upgraded from 1.17 to 1.18.

       It now works in taint mode [perl #72062].

   *   The sigtrap pragma has been upgraded from version 1.04 to 1.05.

       It no longer tries to modify read-only arguments when generating a
       backtrace [perl #72340].

   *   Socket has been upgraded from version 1.87 to 1.94.

       See "Improved IPv6 support" above.

   *   Storable has been upgraded from version 2.22 to 2.27.

       Includes performance improvement for overloaded classes.

       This adds support for serialising code references that contain
       UTF-8 strings correctly.  The Storable minor version number changed
       as a result, meaning that Storable users who set
       $Storable::accept_future_minor to a "FALSE" value will see errors
       (see "FORWARD COMPATIBILITY" in Storable for more details).

       Freezing no longer gets confused if the Perl stack gets reallocated
       during freezing [perl #80074].

   *   Sys::Hostname has been upgraded from version 1.11 to 1.16.

   *   Term::ANSIColor has been upgraded from version 2.02 to 3.00.

   *   Term::UI has been upgraded from version 0.20 to 0.26.

   *   Test::Harness has been upgraded from version 3.17 to 3.23.

   *   Test::Simple has been upgraded from version 0.94 to 0.98.

       Among many other things, subtests without a "plan" or "no_plan" now
       have an implicit done_testing() added to them.

   *   Thread::Semaphore has been upgraded from version 2.09 to 2.12.

       It provides two new methods that give more control over the
       decrementing of semaphores: "down_nb" and "down_force".

   *   Thread::Queue has been upgraded from version 2.11 to 2.12.

   *   The threads pragma has been upgraded from version 1.75 to 1.83.

   *   The threads::shared pragma has been upgraded from version 1.32 to

   *   Tie::Hash has been upgraded from version 1.03 to 1.04.

       Calling "Tie::Hash->TIEHASH()" used to loop forever.  Now it

   *   Tie::Hash::NamedCapture has been upgraded from version 0.06 to

   *   Tie::RefHash has been upgraded from version 1.38 to 1.39.

   *   Time::HiRes has been upgraded from version 1.9719 to 1.9721_01.

   *   Time::Local has been upgraded from version 1.1901_01 to 1.2000.

   *   Time::Piece has been upgraded from version 1.15_01 to 1.20_01.

   *   Unicode::Collate has been upgraded from version 0.52_01 to 0.73.

       Unicode::Collate has been updated to use Unicode 6.0.0.

       Unicode::Collate::Locale now supports a plethora of new locales:
       ar, be, bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig,
       ja, ko, ru, sq, se, sr, to, uk, zh, zh__big5han, zh__gb2312han,
       zh__pinyin, and zh__stroke.

       The following modules have been added:

       Unicode::Collate::CJK::Big5 for "zh__big5han" which makes tailoring
       of CJK Unified Ideographs in the order of CLDR's big5han ordering.

       Unicode::Collate::CJK::GB2312 for "zh__gb2312han" which makes
       tailoring of CJK Unified Ideographs in the order of CLDR's
       gb2312han ordering.

       Unicode::Collate::CJK::JISX0208 which makes tailoring of 6355 kanji
       (CJK Unified Ideographs) in the JIS X 0208 order.

       Unicode::Collate::CJK::Korean which makes tailoring of CJK Unified
       Ideographs in the order of CLDR's Korean ordering.

       Unicode::Collate::CJK::Pinyin for "zh__pinyin" which makes
       tailoring of CJK Unified Ideographs in the order of CLDR's pinyin

       Unicode::Collate::CJK::Stroke for "zh__stroke" which makes
       tailoring of CJK Unified Ideographs in the order of CLDR's stroke

       This also sees the switch from using the pure-Perl version of this
       module to the XS version.

   *   Unicode::Normalize has been upgraded from version 1.03 to 1.10.

   *   Unicode::UCD has been upgraded from version 0.27 to 0.32.

       A new function, Unicode::UCD::num(), has been added.  This function
       returns the numeric value of the string passed it or "undef" if the
       string in its entirety has no "safe" numeric value.  (For more
       detail, and for the definition of "safe", see "num()" in

       This upgrade also includes several bug fixes:

           *   It is now updated to Unicode Version 6.0.0 with Corrigendum
               #8, excepting that, just as with Perl 5.14, the code point
               at U+1F514 has no name.

           *   Hangul syllable code points have the correct names, and
               their decompositions are always output without requiring
               Lingua::KO::Hangul::Util to be installed.

           *   CJK (Chinese-Japanese-Korean) code points U+2A700 to
               U+2B734 and U+2B740 to U+2B81D are now properly handled.

           *   Numeric values are now output for those CJK code points
               that have them.

           *   Names output for code points with multiple aliases are now
               the corrected ones.

           This now correctly returns "Unknown" instead of "undef" for the
           script of a code point that hasn't been assigned another one.

           This now correctly returns "No_Block" instead of "undef" for
           the block of a code point that hasn't been assigned to another

   *   The version pragma has been upgraded from 0.82 to 0.88.

       Because of a bug, now fixed, the is_strict() and is_lax() functions
       did not work when exported (5.12.1).

   *   The warnings pragma has been upgraded from version 1.09 to 1.12.

       Calling "use warnings" without arguments is now significantly more

   *   The warnings::register pragma has been upgraded from version 1.01
       to 1.02.

       It is now possible to register warning categories other than the
       names of packages using warnings::register.  See perllexwarn(1) for
       more information.

   *   XSLoader has been upgraded from version 0.10 to 0.13.

   *   VMS::DCLsym has been upgraded from version 1.03 to 1.05.

       Two bugs have been fixed [perl #84086]:

       The symbol table name was lost when tying a hash, due to a thinko
       in "TIEHASH".  The result was that all tied hashes interacted with
       the local symbol table.

       Unless a symbol table name had been explicitly specified in the
       call to the constructor, querying the special key ":LOCAL" failed
       to identify objects connected to the local symbol table.

   *   The Win32 module has been upgraded from version 0.39 to 0.44.

       This release has several new functions: Win32::GetSystemMetrics(),
       Win32::GetProductInfo(), Win32::GetOSDisplayName().

       The names returned by Win32::GetOSName() and
       Win32::GetOSDisplayName() have been corrected.

   *   XS::Typemap has been upgraded from version 0.03 to 0.05.

   Removed Modules and Pragmata
   As promised in Perl 5.12.0's release notes, the following modules have
   been removed from the core distribution, and if needed should be
   installed from CPAN instead.

   *   Class::ISA has been removed from the Perl core.  Prior version was

   *   Pod::Plainer has been removed from the Perl core.  Prior version
       was 1.02.

   *   Switch has been removed from the Perl core.  Prior version was

   The removal of Shell has been deferred until after 5.14, as the
   implementation of Shell shipped with 5.12.0 did not correctly issue the
   warning that it was to be removed from core.


   New Documentation

   perlgpl has been updated to contain GPL version 1, as is included in
   the README distributed with Perl (5.12.1).

   Perl 5.12.x delta files

   The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
   maintenance branch: perl5121delta, perl5122delta, perl5123delta.


   New style guide for POD documentation, split mostly from the NOTES
   section of the pod2man(1) manpage.

   perlsource, perlinterp, perlhacktut, and perlhacktips

   See "perlhack and perlrepository revamp", below.

   Changes to Existing Documentation
   perlmodlib is now complete

   The perlmodlib manpage that came with Perl 5.12.0 was missing several
   modules due to a bug in the script that generates the list.  This has
   been fixed [perl #74332] (5.12.1).

   Replace incorrect tr/// table in perlebcdic

   perlebcdic contains a helpful table to use in "tr///" to convert
   between EBCDIC and Latin1/ASCII.  The table was the inverse of the one
   it describes, though the code that used the table worked correctly for
   the specific example given.

   The table has been corrected and the sample code changed to correspond.

   The table has also been changed to hex from octal, and the recipes in
   the pod have been altered to print out leading zeros to make all values
   the same length.

   Tricks for user-defined casing

   perlunicode now contains an explanation of how to override, mangle and
   otherwise tweak the way Perl handles upper-, lower- and other-case
   conversions on Unicode data, and how to provide scoped changes to alter
   one's own code's behaviour without stomping on anybody else's.

   INSTALL explicitly states that Perl requires a C89 compiler

   This was already true, but it's now Officially Stated For The Record

   Explanation of "\xHH" and "\oOOO" escapes

   perlop has been updated with more detailed explanation of these two
   character escapes.

   -0NNN switch

   In perlrun, the behaviour of the -0NNN switch for -0400 or higher has
   been clarified (5.12.2).

   Maintenance policy

   perlpolicy now contains the policy on what patches are acceptable for
   maintenance branches (5.12.1).

   Deprecation policy

   perlpolicy now contains the policy on compatibility and deprecation
   along with definitions of terms like "deprecation" (5.12.2).

   New descriptions in perldiag

   The following existing diagnostics are now documented:

   *   Ambiguous use of %c resolved as operator %c

   *   Ambiguous use of %c{%s} resolved to %c%s

   *   Ambiguous use of %c{%s[...]} resolved to %c%s[...]

   *   Ambiguous use of %c{%s{...}} resolved to %c%s{...}

   *   Ambiguous use of -%s resolved as -&%s()

   *   Invalid strict version format (%s)

   *   Invalid version format (%s)

   *   Invalid version object


   perlbook has been expanded to cover many more popular books.

   "SvTRUE" macro

   The documentation for the "SvTRUE" macro in perlapi was simply wrong in
   stating that get-magic is not processed.  It has been corrected.

   op manipulation functions

   Several API functions that process optrees have been newly documented.

   perlvar revamp

   perlvar reorders the variables and groups them by topic.  Each variable
   introduced after Perl 5.000 notes the first version in which it is
   available.  perlvar also has a new section for deprecated variables to
   note when they were removed.

   Array and hash slices in scalar context

   These are now documented in perldata.

   "use locale" and formats

   perlform and perllocale have been corrected to state that "use locale"
   affects formats.


   overload's documentation has practically undergone a rewrite.  It is
   now much more straightforward and clear.

   perlhack and perlrepository revamp

   The perlhack document is now much shorter, and focuses on the Perl 5
   development process and submitting patches to Perl.  The technical
   content has been moved to several new documents, perlsource,
   perlinterp, perlhacktut, and perlhacktips.  This technical content has
   been only lightly edited.

   The perlrepository document has been renamed to perlgit.  This new
   document is just a how-to on using git with the Perl source code.  Any
   other content that used to be in perlrepository has been moved to

   Time::Piece examples

   Examples in perlfaq4 have been updated to show the use of Time::Piece.


   The following additions or changes have been made to diagnostic output,
   including warnings and fatal error messages.  For the complete list of
   diagnostic messages, see perldiag.

   New Diagnostics
   New Errors

   Closure prototype called
       This error occurs when a subroutine reference passed to an
       attribute handler is called, if the subroutine is a closure [perl

   Insecure user-defined property %s
       Perl detected tainted data when trying to compile a regular
       expression that contains a call to a user-defined character
       property function, meaning "\p{IsFoo}" or "\p{InFoo}".  See "User-
       Defined Character Properties" in perlunicode and perlsec.

   panic: gp_free failed to free glob pointer - something is repeatedly
   re-creating entries
       This new error is triggered if a destructor called on an object in
       a typeglob that is being freed creates a new typeglob entry
       containing an object with a destructor that creates a new entry
       containing an object etc.

   Parsing code internal error (%s)
       This new fatal error is produced when parsing code supplied by an
       extension violates the parser's API in a detectable way.

   refcnt: fd %d%s
       This new error only occurs if a internal consistency check fails
       when a pipe is about to be closed.

   Regexp modifier "/%c" may not appear twice
       The regular expression pattern has one of the mutually exclusive
       modifiers repeated.

   Regexp modifiers "/%c" and "/%c" are mutually exclusive
       The regular expression pattern has more than one of the mutually
       exclusive modifiers.

   Using !~ with %s doesn't make sense
       This error occurs when "!~" is used with "s///r" or "y///r".

   New Warnings

   "\b{" is deprecated; use "\b\{" instead
   "\B{" is deprecated; use "\B\{" instead
       Use of an unescaped "{" immediately following a "\b" or "\B" is now
       deprecated in order to reserve its use for Perl itself in a future

   Operation "%s" returns its argument for ...
       Performing an operation requiring Unicode semantics (such as case-
       folding) on a Unicode surrogate or a non-Unicode character now
       triggers this warning.

   Use of qw(...) as parentheses is deprecated
       See "Use of qw(...) as parentheses", above, for details.

   Changes to Existing Diagnostics
   *   The "Variable $foo is not imported" warning that precedes a "strict
       'vars'" error has now been assigned the "misc" category, so that
       "no warnings" will suppress it [perl #73712].

   *   warn() and die() now produce "Wide character" warnings when fed a
       character outside the byte range if "STDERR" is a byte-sized

   *   The "Layer does not match this perl" error message has been
       replaced with these more helpful messages [perl #73754]:

       *   PerlIO layer function table size (%d) does not match size
           expected by this perl (%d)

       *   PerlIO layer instance size (%d) does not match size expected by
           this perl (%d)

   *   The "Found = in conditional" warning that is emitted when a
       constant is assigned to a variable in a condition is now withheld
       if the constant is actually a subroutine or one generated by "use
       constant", since the value of the constant may not be known at the
       time the program is written [perl #77762].

   *   Previously, if none of the gethostbyaddr(), gethostbyname() and
       gethostent() functions were implemented on a given platform, they
       would all die with the message "Unsupported socket function
       'gethostent' called", with analogous messages for getnet*() and
       getserv*().  This has been corrected.

   *   The warning message about unrecognized regular expression escapes
       passed through has been changed to include any literal "{"
       following the two-character escape.  For example, "\q{" is now
       emitted instead of "\q".

Utility Changes


   *   perlbug now looks in the EMAIL environment variable for a return
       address if the REPLY-TO and REPLYTO variables are empty.

   *   perlbug did not previously generate a "From:" header, potentially
       resulting in dropped mail; it now includes that header.

   *   The user's address is now used as the Return-Path.

       Many systems these days don't have a valid Internet domain name,
       and does not accept email with a return-path that
       does not resolve.  So the user's address is now passed to sendmail
       so it's less likely to get stuck in a mail queue somewhere [perl

   *   perlbug now always gives the reporter a chance to change the email
       address it guesses for them (5.12.2).

   *   perlbug should no longer warn about uninitialized values when using
       the -d and -v options (5.12.2).

   *   The remote terminal works after forking and spawns new sessions,
       one per forked process.


   *   ptargrep is a new utility to apply pattern matching to the contents
       of files  in a tar archive.  It comes with "Archive::Tar".

Configuration and Compilation

   See also "Naming fixes in Policy_sh.SH may invalidate",

   *   CCINCDIR and CCLIBDIR for the mingw64 cross-compiler are now
       correctly under $(CCHOME)\mingw\include and \lib rather than
       immediately below $(CCHOME).

       This means the "incpath", "libpth", "ldflags", "lddlflags" and
       "ldflags_nolargefiles" values in and are
       now set correctly.

   *   "make test.valgrind" has been adjusted to account for cpan/dist/ext

   *   On compilers that support it, -Wwrite-strings is now added to
       cflags by default.

   *   The Encode module can now (once again) be included in a static Perl
       build.  The special-case handling for this situation got broken in
       Perl 5.11.0, and has now been repaired.

   *   The previous default size of a PerlIO buffer (4096 bytes) has been
       increased to the larger of 8192 bytes and your local BUFSIZ.
       Benchmarks show that doubling this decade-old default increases
       read and write performance by around 25% to 50% when using the
       default layers of perlio on top of unix.  To choose a non-default
       size, such as to get back the old value or to obtain an even larger
       value, configure with:

            ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N

       where N is the desired size in bytes; it should probably be a
       multiple of your page size.

   *   An "incompatible operand types" error in ternary expressions when
       building with "clang" has been fixed (5.12.2).

   *   Perl now skips setuid File::Copy tests on partitions it detects
       mounted as "nosuid" (5.12.2).

Platform Support

   New Platforms
   AIX Perl now builds on AIX 4.2 (5.12.1).

   Discontinued Platforms
   Apollo DomainOS
       The last vestiges of support for this platform have been excised
       from the Perl distribution.  It was officially discontinued in
       version 5.12.0.  It had not worked for years before that.

   MacOS Classic
       The last vestiges of support for this platform have been excised
       from the Perl distribution.  It was officially discontinued in an
       earlier version.

   Platform-Specific Notes

   *   README.aix has been updated with information about the XL C/C++ V11
       compiler suite (5.12.2).


   *   The "d_u32align" configuration probe on ARM has been fixed


   *   MakeMaker has been updated to build manpages on cygwin.

   *   Improved rebase behaviour

       If a DLL is updated on cygwin the old imagebase address is reused.
       This solves most rebase errors, especially when updating on core
       DLL's.  See
       for more information.

   *   Support for the standard cygwin dll prefix (needed for FFIs)

   *   Updated build hints file

   FreeBSD 7

   *   FreeBSD 7 no longer contains /usr/bin/objformat.  At build time,
       Perl now skips the objformat check for versions 7 and higher and
       assumes ELF (5.12.1).


   *   Perl now allows -Duse64bitint without promoting to "use64bitall" on
       HP-UX (5.12.1).


   *   Conversion of strings to floating-point numbers is now more
       accurate on IRIX systems [perl #32380].

   Mac OS X

   *   Early versions of Mac OS X (Darwin) had buggy implementations of
       the setregid(), setreuid(), setrgid(,) and setruid() functions, so
       Perl would pretend they did not exist.

       These functions are now recognised on Mac OS 10.5 (Leopard; Darwin
       9) and higher, as they have been fixed [perl #72990].


   *   Previously if you built Perl with a shared on MirBSD
       (the default config), it would work up to the installation;
       however, once installed, it would be unable to find libperl.  Path
       handling is now treated as in the other BSD dialects.


   *   The NetBSD hints file has been changed to make the system malloc
       the default.


   *   OpenBSD > 3.7 has a new malloc implementation which is mmap-based,
       and as such can release memory back to the OS; however, Perl's use
       of this malloc causes a substantial slowdown, so we now default to
       using Perl's malloc instead [perl #75742].


   *   Perl now builds again with OpenVOS (formerly known as Stratus VOS)
       [perl #78132] (5.12.3).


   *   DTrace is now supported on Solaris.  There used to be build
       failures, but these have been fixed [perl #73630] (5.12.3).


   *   Extension building on older (pre 7.3-2) VMS systems was broken
       because hit the DCL symbol length limit of 1K.  We
       now work within this limit when assembling the list of extensions
       in the core build (5.12.1).

   *   We fixed configuring and building Perl with -Uuseperlio (5.12.1).

   *   "PerlIOUnix_open" now honours the default permissions on VMS.

       When "perlio" became the default and "unix" became the default
       bottom layer, the most common path for creating files from Perl
       became "PerlIOUnix_open", which has always explicitly used 0666 as
       the permission mask.  This prevents inheriting permissions from RMS
       defaults and ACLs, so to avoid that problem, we now pass 0777 to
       open().  In the VMS CRTL, 0777 has a special meaning over and above
       intersecting with the current umask; specifically, it allows Unix
       syscalls to preserve native default permissions (5.12.3).

   *   The shortening of symbols longer than 31 characters in the core C
       sources and in extensions is now by default done by the C compiler
       rather than by xsubpp (which could only do so for generated symbols
       in XS code).  You can reenable xsubpp's symbol shortening by
       configuring with -Uuseshortenedsymbols, but you'll have some work
       to do to get the core sources to compile.

   *   Record-oriented files (record format variable or variable with
       fixed control) opened for write by the "perlio" layer will now be
       line-buffered to prevent the introduction of spurious line breaks
       whenever the perlio buffer fills up.

   *   git_version.h is now installed on VMS.  This was an oversight in
       v5.12.0 which caused some extensions to fail to build (5.12.2).

   *   Several memory leaks in stat() have been fixed (5.12.2).

   *   A memory leak in Perl_rename() due to a double allocation has been
       fixed (5.12.2).

   *   A memory leak in vms_fid_to_name() (used by realpath() and
       realname()> has been fixed (5.12.2).


   See also "fork() emulation will not wait for signalled children" and
   "Perl source code is read in text mode on Windows", above.

   *   Fixed build process for SDK2003SP1 compilers.

   *   Compilation with Visual Studio 2010 is now supported.

   *   When using old 32-bit compilers, the define "_USE_32BIT_TIME_T" is
       now set in $Config{ccflags}.  This improves portability when
       compiling XS extensions using new compilers, but for a Perl
       compiled with old 32-bit compilers.

   *   $Config{gccversion} is now set correctly when Perl is built using
       the mingw64 compiler from <> [perl #73754].

   *   When building Perl with the mingw64 x64 cross-compiler "incpath",
       "libpth", "ldflags", "lddlflags" and "ldflags_nolargefiles" values
       in and were not previously being set
       correctly because, with that compiler, the include and lib
       directories are not immediately below "$(CCHOME)" (5.12.2).

   *   The build process proceeds more smoothly with mingw and dmake when
       C:\MSYS\bin is in the PATH, due to a "Cwd" fix.

   *   Support for building with Visual C++ 2010 is now underway, but is
       not yet complete.  See README.win32 or perlwin32 for more details.

   *   The option to use an externally-supplied crypt(), or to build with
       no crypt() at all, has been removed.  Perl supplies its own crypt()
       implementation for Windows, and the political situation that
       required this part of the distribution to sometimes be omitted is
       long gone.

Internal Changes

   New APIs
   CLONE_PARAMS structure added to ease correct thread creation

   Modules that create threads should now create "CLONE_PARAMS" structures
   by calling the new function Perl_clone_params_new(), and free them with
   Perl_clone_params_del().  This will ensure compatibility with any
   future changes to the internals of the "CLONE_PARAMS" structure layout,
   and that it is correctly allocated and initialised.

   New parsing functions

   Several functions have been added for parsing Perl statements and
   expressions.  These functions are meant to be used by XS code invoked
   during Perl parsing, in a recursive-descent manner, to allow modules to
   augment the standard Perl syntax.

   *   parse_stmtseq() parses a sequence of statements, up to closing
       brace or EOF.

   *   parse_fullstmt() parses a complete Perl statement, including
       optional label.

   *   parse_barestmt() parses a statement without a label.

   *   parse_block() parses a code block.

   *   parse_label() parses a statement label, separate from statements.

   *   "parse_fullexpr()", "parse_listexpr()", "parse_termexpr()", and
       "parse_arithexpr()" parse expressions at various precedence levels.

   Hints hash API

   A new C API for introspecting the hinthash "%^H" at runtime has been
   added.  See "cop_hints_2hv", "cop_hints_fetchpvn",
   "cop_hints_fetchpvs", "cop_hints_fetchsv", and "hv_copy_hints_hv" in
   perlapi for details.

   A new, experimental API has been added for accessing the internal
   structure that Perl uses for "%^H".  See the functions beginning with
   "cophh_" in perlapi.

   C interface to caller()

   The "caller_cx" function has been added as an XSUB-writer's equivalent
   of caller().  See perlapi for details.

   Custom per-subroutine check hooks

   XS code in an extension module can now annotate a subroutine (whether
   implemented in XS or in Perl) so that nominated XS code will be called
   at compile time (specifically as part of op checking) to change the op
   tree of that subroutine.  The compile-time check function (supplied by
   the extension module) can implement argument processing that can't be
   expressed as a prototype, generate customised compile-time warnings,
   perform constant folding for a pure function, inline a subroutine
   consisting of sufficiently simple ops, replace the whole call with a
   custom op, and so on.  This was previously all possible by hooking the
   "entersub" op checker, but the new mechanism makes it easy to tie the
   hook to a specific subroutine.  See "cv_set_call_checker" in perlapi.

   To help in writing custom check hooks, several subtasks within standard
   "entersub" op checking have been separated out and exposed in the API.

   Improved support for custom OPs

   Custom ops can now be registered with the new "custom_op_register" C
   function and the "XOP" structure.  This will make it easier to add new
   properties of custom ops in the future.  Two new properties have been
   added already, "xop_class" and "xop_peep".

   "xop_class" is one of the OA_*OP constants.  It allows B and other
   introspection mechanisms to work with custom ops that aren't BASEOPs.
   "xop_peep" is a pointer to a function that will be called for ops of
   this type from "Perl_rpeep".

   See "Custom Operators" in perlguts and "Custom Operators" in perlapi
   for more detail.

   The old "PL_custom_op_names"/"PL_custom_op_descs" interface is still
   supported but discouraged.

   Scope hooks

   It is now possible for XS code to hook into Perl's lexical scope
   mechanism at compile time, using the new "Perl_blockhook_register"
   function.  See "Compile-time scope hooks" in perlguts.

   The recursive part of the peephole optimizer is now hookable

   In addition to "PL_peepp", for hooking into the toplevel peephole
   optimizer, a "PL_rpeepp" is now available to hook into the optimizer
   recursing into side-chains of the optree.

   New non-magical variants of existing functions

   The following functions/macros have been added to the API.  The *_nomg
   macros are equivalent to their non-"_nomg" variants, except that they
   ignore get-magic.  Those ending in "_flags" allow one to specify
   whether get-magic is processed.


   In some of these cases, the non-"_flags" functions have been replaced
   with wrappers around the new functions.

   pv/pvs/sv versions of existing functions

   Many functions ending with pvn now have equivalent "pv/pvs/sv"

   List op-building functions

   List op-building functions have been added to the API.  See
   op_append_elem, op_append_list, and op_prepend_elem in perlapi.


   The LINKLIST macro, part of op building that constructs the execution-
   order op chain, has been added to the API.

   Localisation functions

   The "save_freeop", "save_op", "save_pushi32ptr" and "save_pushptrptr"
   functions have been added to the API.

   Stash names

   A stash can now have a list of effective names in addition to its usual
   name.  The first effective name can be accessed via the "HvENAME"
   macro, which is now the recommended name to use in MRO linearisations
   ("HvNAME" being a fallback if there is no "HvENAME").

   These names are added and deleted via "hv_ename_add" and
   "hv_ename_delete".  These two functions are not part of the API.

   New functions for finding and removing magic

   The "mg_findext()" and "sv_unmagicext()" functions have been added to
   the API.  They allow extension authors to find and remove magic
   attached to scalars based on both the magic type and the magic virtual
   table, similar to how sv_magicext() attaches magic of a certain type
   and with a given virtual table to a scalar.  This eliminates the need
   for extensions to walk the list of "MAGIC" pointers of an "SV" to find
   the magic that belongs to them.


   This function returns the SV representing $_, whether it's lexical or


   Perl_croak_no_modify() is short-hand for "Perl_croak("%s",


   The "PERL_STATIC_INLINE" define has been added to provide the best-
   guess incantation to use for static inline functions, if the C compiler
   supports C99-style static inline.  If it doesn't, it'll give a plain

   "HAS_STATIC_INLINE" can be used to check if the compiler actually
   supports inline functions.

   New "pv_escape" option for hexadecimal escapes

   A new option, "PERL_PV_ESCAPE_NONASCII", has been added to "pv_escape"
   to dump all characters above ASCII in hexadecimal.  Before, one could
   get all characters as hexadecimal or the Latin1 non-ASCII as octal.


   "lex_start" has been added to the API, but is considered experimental.

   op_scope() and op_lvalue()

   The op_scope() and op_lvalue() functions have been added to the API,
   but are considered experimental.

   C API Changes
   "PERL_POLLUTE" has been removed

   The option to define "PERL_POLLUTE" to expose older 5.005 symbols for
   backwards compatibility has been removed.  Its use was always
   discouraged, and MakeMaker contains a more specific escape hatch:

       perl Makefile.PL POLLUTE=1

   This can be used for modules that have not been upgraded to 5.6 naming
   conventions (and really should be completely obsolete by now).

   Check API compatibility when loading XS modules

   When Perl's API changes in incompatible ways (which usually happens
   between major releases), XS modules compiled for previous versions of
   Perl will no longer work.  They need to be recompiled against the new

   The "XS_APIVERSION_BOOTCHECK" macro has been added to ensure that
   modules are recompiled and to prevent users from accidentally loading
   modules compiled for old perls into newer perls.  That macro, which is
   called when loading every newly compiled extension, compares the API
   version of the running perl with the version a module has been compiled
   for and raises an exception if they don't match.


   The first argument of the C API function "Perl_fetch_cop_label" has
   changed from "struct refcounted_he *" to "COP *", to insulate the user
   from implementation details.

   This API function was marked as "may change", and likely isn't in use
   outside the core.  (Neither an unpacked CPAN nor Google's codesearch
   finds any other references to it.)

   GvCV() and GvGP() are no longer lvalues

   The new GvCV_set() and GvGP_set() macros are now provided to replace
   assignment to those two macros.

   This allows a future commit to eliminate some backref magic between GV
   and CVs, which will require complete control over assignment to the
   "gp_cv" slot.

   CvGV() is no longer an lvalue

   Under some circumstances, the CvGV() field of a CV is now reference-
   counted.  To ensure consistent behaviour, direct assignment to it, for
   example "CvGV(cv) = gv" is now a compile-time error.  A new macro,
   "CvGV_set(cv,gv)" has been introduced to run this operation safely.
   Note that modification of this field is not part of the public API,
   regardless of this new macro (and despite its being listed in this

   CvSTASH() is no longer an lvalue

   The CvSTASH() macro can now only be used as an rvalue.  CvSTASH_set()
   has been added to replace assignment to CvSTASH().  This is to ensure
   that backreferences are handled properly.  These macros are not part of
   the API.

   Calling conventions for "newFOROP" and "newWHILEOP"

   The way the parser handles labels has been cleaned up and refactored.
   As a result, the newFOROP() constructor function no longer takes a
   parameter stating what label is to go in the state op.

   The newWHILEOP() and newFOROP() functions no longer accept a line
   number as a parameter.

   Flags passed to "uvuni_to_utf8_flags" and "utf8n_to_uvuni"

   Some of the flags parameters to uvuni_to_utf8_flags() and
   utf8n_to_uvuni() have changed.  This is a result of Perl's now allowing
   internal storage and manipulation of code points that are problematic
   in some situations.  Hence, the default actions for these functions has
   been complemented to allow these code points.  The new flags are
   documented in perlapi.  Code that requires the problematic code points
   to be rejected needs to change to use the new flags.  Some flag names
   are retained for backward source compatibility, though they do nothing,
   as they are now the default.  However the flags "UNICODE_ALLOW_FDD0",
   been removed, as they stem from a fundamentally broken model of how the
   Unicode non-character code points should be handled, which is now
   described in "Non-character code points" in perlunicode.  See also the
   Unicode section under "Selected Bug Fixes".

   Deprecated C APIs
       "Perl_ptr_table_clear" is no longer part of Perl's public API.
       Calling it now generates a deprecation warning, and it will be
       removed in a future release.

       The sv_compile_2op() API function is now deprecated.  Searches
       suggest that nothing on CPAN is using it, so this should have zero

       It attempted to provide an API to compile code down to an optree,
       but failed to bind correctly to lexicals in the enclosing scope.
       It's not possible to fix this problem within the constraints of its
       parameters and return value.

       The "find_rundefsvoffset" function has been deprecated.  It
       appeared that its design was insufficient for reliably getting the
       lexical $_ at run-time.

       Use the new "find_rundefsv" function or the "UNDERBAR" macro
       instead.  They directly return the right SV representing $_,
       whether it's lexical or dynamic.

   "CALL_FPTR" and "CPERLscope"
       Those are left from an old implementation of "MULTIPLICITY" using
       C++ objects, which was removed in Perl 5.8.  Nowadays these macros
       do exactly nothing, so they shouldn't be used anymore.

       For compatibility, they are still defined for external "XS" code.
       Only extensions defining "PERL_CORE" must be updated now.

   Other Internal Changes
   Stack unwinding

   The protocol for unwinding the C stack at the last stage of a "die" has
   changed how it identifies the target stack frame.  This now uses a
   separate variable "PL_restartjmpenv", where previously it relied on the
   "blk_eval.cur_top_env" pointer in the "eval" context frame that has
   nominally just been discarded.  This change means that code running
   during various stages of Perl-level unwinding no longer needs to take
   care to avoid destroying the ghost frame.

   Scope stack entries

   The format of entries on the scope stack has been changed, resulting in
   a reduction of memory usage of about 10%.  In particular, the memory
   used by the scope stack to record each active lexical variable has been

   Memory allocation for pointer tables

   Memory allocation for pointer tables has been changed.  Previously
   "Perl_ptr_table_store" allocated memory from the same arena system as
   "SV" bodies and "HE"s, with freed memory remaining bound to those
   arenas until interpreter exit.  Now it allocates memory from arenas
   private to the specific pointer table, and that memory is returned to
   the system when "Perl_ptr_table_free" is called.  Additionally,
   allocation and release are both less CPU intensive.


   The "UNDERBAR" macro now calls "find_rundefsv".  "dUNDERBAR" is now a
   noop but should still be used to ensure past and future compatibility.

   String comparison routines renamed

   The "ibcmp_*" functions have been renamed and are now called "foldEQ",
   "foldEQ_locale", and "foldEQ_utf8".  The old names are still available
   as macros.

   "chop" and "chomp" implementations merged

   The opcode bodies for "chop" and "chomp" and for "schop" and "schomp"
   have been merged.  The implementation functions Perl_do_chop() and
   Perl_do_chomp(), never part of the public API, have been merged and
   moved to a static function in pp.c.  This shrinks the Perl binary
   slightly, and should not affect any code outside the core (unless it is
   relying on the order of side-effects when "chomp" is passed a list of

Selected Bug Fixes

   *   Perl no longer produces this warning:

           $ perl -we 'open(my $f, ">", \my $x); binmode($f, "scalar")'
           Use of uninitialized value in binmode at -e line 1.

   *   Opening a glob reference via "open($fh, ">", \*glob)" no longer
       causes the glob to be corrupted when the filehandle is printed to.
       This would cause Perl to crash whenever the glob's contents were
       accessed [perl #77492].

   *   PerlIO no longer crashes when called recursively, such as from a
       signal handler.  Now it just leaks memory [perl #75556].

   *   Most I/O functions were not warning for unopened handles unless the
       "closed" and "unopened" warnings categories were both enabled.  Now
       only "use warnings 'unopened'" is necessary to trigger these
       warnings, as had always been the intention.

   *   There have been several fixes to PerlIO layers:

       When "binmode(FH, ":crlf")" pushes the ":crlf" layer on top of the
       stack, it no longer enables crlf layers lower in the stack so as to
       avoid unexpected results [perl #38456].

       Opening a file in ":raw" mode now does what it advertises to do
       (first open the file, then "binmode" it), instead of simply leaving
       off the top layer [perl #80764].

       The three layers ":pop", ":utf8", and ":bytes" didn't allow
       stacking when opening a file.  For example this:

           open(FH, ">:pop:perlio", "some.file") or die $!;

       would throw an "Invalid argument" error.  This has been fixed in
       this release [perl #82484].

   Regular Expression Bug Fixes
   *   The regular expression engine no longer loops when matching
       ""\N{LATIN SMALL LIGATURE FF}" =~ /f+/i" and similar expressions
       [perl #72998] (5.12.1).

   *   The trie runtime code should no longer allocate massive amounts of
       memory, fixing #74484.

   *   Syntax errors in "(?{...})" blocks no longer cause panic messages
       [perl #2353].

   *   A pattern like "(?:(o){2})?" no longer causes a "panic" error [perl

   *   A fatal error in regular expressions containing "(.*?)" when
       processing UTF-8 data has been fixed [perl #75680] (5.12.2).

   *   An erroneous regular expression engine optimisation that caused
       regex verbs like *COMMIT sometimes to be ignored has been removed.

   *   The regular expression bracketed character class "[\8\9]" was
       effectively the same as "[89\000]", incorrectly matching a NULL
       character.  It also gave incorrect warnings that the 8 and 9 were
       ignored.  Now "[\8\9]" is the same as "[89]" and gives legitimate
       warnings that "\8" and "\9" are unrecognized escape sequences,

   *   A regular expression match in the right-hand side of a global
       substitution ("s///g") that is in the same scope will no longer
       cause match variables to have the wrong values on subsequent
       iterations.  This can happen when an array or hash subscript is
       interpolated in the right-hand side, as in "s|(.)|@a{ print($1),
       /./ }|g" [perl #19078].

   *   Several cases in which characters in the Latin-1 non-ASCII range
       (0x80 to 0xFF) used not to match themselves, or used to match both
       a character class and its complement, have been fixed.  For
       instance, U+00E2 could match both "\w" and "\W" [perl #78464] [perl
       #18281] [perl #60156].

   *   Matching a Unicode character against an alternation containing
       characters that happened to match continuation bytes in the
       former's UTF8 representation (like "qq{\x{30ab}} =~ /\xab|\xa9/")
       would cause erroneous warnings [perl #70998].

   *   The trie optimisation was not taking empty groups into account,
       preventing "foo" from matching "/\A(?:(?:)foo|bar|zot)\z/" [perl

   *   A pattern containing a "+" inside a lookahead would sometimes cause
       an incorrect match failure in a global match (for example,
       "/(?=(\S+))/g") [perl #68564].

   *   A regular expression optimisation would sometimes cause a match
       with a "{n,m}" quantifier to fail when it should have matched [perl

   *   Case-insensitive matching in regular expressions compiled under
       "use locale" now works much more sanely when the pattern or target
       string is internally encoded in UTF8.  Previously, under these
       conditions the localeness was completely lost.  Now, code points
       above 255 are treated as Unicode, but code points between 0 and 255
       are treated using the current locale rules, regardless of whether
       the pattern or the string is encoded in UTF8.  The few case-
       insensitive matches that cross the 255/256 boundary are not
       allowed.  For example, 0xFF does not caselessly match the character
       at 0x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may
       not be LATIN SMALL LETTER Y in the current locale, and Perl has no
       way of knowing if that character even exists in the locale, much
       less what code point it is.

   *   The "(?|...)" regular expression construct no longer crashes if the
       final branch has more sets of capturing parentheses than any other
       branch.  This was fixed in Perl 5.10.1 for the case of a single
       branch, but that fix did not take multiple branches into account
       [perl #84746].

   *   A bug has been fixed in the implementation of "{...}" quantifiers
       in regular expressions that prevented the code block in "/((\w+)(?{
       print $2 })){2}/" from seeing the $2 sometimes [perl #84294].

   Syntax/Parsing Bugs
   *   "when (scalar) {...}" no longer crashes, but produces a syntax
       error [perl #74114] (5.12.1).

   *   A label right before a string eval ("foo: eval $string") no longer
       causes the label to be associated also with the first statement
       inside the eval [perl #74290] (5.12.1).

   *   The "no 5.13.2" form of "no" no longer tries to turn on features or
       pragmata (like strict) [perl #70075] (5.12.2).

   *   "BEGIN {require 5.12.0}" now behaves as documented, rather than
       behaving identically to "use 5.12.0".  Previously, "require" in a
       "BEGIN" block was erroneously executing the "use feature ':5.12.0'"
       and "use strict" behaviour, which only "use" was documented to
       provide [perl #69050].

   *   A regression introduced in Perl 5.12.0, making "my $x = 3; $x =
       length(undef)" result in $x set to 3 has been fixed.  $x will now
       be "undef" [perl #85508] (5.12.2).

   *   When strict "refs" mode is off, "%{...}" in rvalue context returns
       "undef" if its argument is undefined.  An optimisation introduced
       in Perl 5.12.0 to make "keys %{...}" faster when used as a boolean
       did not take this into account, causing "keys %{+undef}" (and "keys
       %$foo" when $foo is undefined) to be an error, which it should be
       so in strict mode only [perl #81750].

   *   Constant-folding used to cause

         $text =~ ( 1 ? /phoo/ : /bear/)

       to turn into

         $text =~ /phoo/

       at compile time.  Now it correctly matches against $_ [perl

   *   Parsing Perl code (either with string "eval" or by loading modules)
       from within a "UNITCHECK" block no longer causes the interpreter to
       crash [perl #70614].

   *   String "eval"s no longer fail after 2 billion scopes have been
       compiled [perl #83364].

   *   The parser no longer hangs when encountering certain Unicode
       characters, such as U+387 [perl #74022].

   *   Defining a constant with the same name as one of Perl's special
       blocks (like "INIT") stopped working in 5.12.0, but has now been
       fixed [perl #78634].

   *   A reference to a literal value used as a hash key ($hash{\"foo"})
       used to be stringified, even if the hash was tied [perl #79178].

   *   A closure containing an "if" statement followed by a constant or
       variable is no longer treated as a constant [perl #63540].

   *   "state" can now be used with attributes.  It used to mean the same
       thing as "my" if any attributes were present [perl #68658].

   *   Expressions like "@$a > 3" no longer cause $a to be mentioned in
       the "Use of uninitialized value in numeric gt" warning when $a is
       undefined (since it is not part of the ">" expression, but the
       operand of the "@") [perl #72090].

   *   Accessing an element of a package array with a hard-coded number
       (as opposed to an arbitrary expression) would crash if the array
       did not exist.  Usually the array would be autovivified during
       compilation, but typeglob manipulation could remove it, as in these
       two cases which used to crash:

         *d = *a;  print $d[0];
         undef *d; print $d[0];

   *   The -C command-line option, when used on the shebang line, can now
       be followed by other options [perl #72434].

   *   The "B" module was returning "B::OP"s instead of "B::LOGOP"s for
       "entertry" [perl #80622].  This was due to a bug in the Perl core,
       not in "B" itself.

   Stashes, Globs and Method Lookup
   Perl 5.10.0 introduced a new internal mechanism for caching MROs
   (method resolution orders, or lists of parent classes; aka "isa"
   caches) to make method lookup faster (so @ISA arrays would not have to
   be searched repeatedly).  Unfortunately, this brought with it quite a
   few bugs.  Almost all of these have been fixed now, along with a few
   MRO-related bugs that existed before 5.10.0:

   *   The following used to have erratic effects on method resolution,
       because the "isa" caches were not reset or otherwise ended up
       listing the wrong classes.  These have been fixed.

       Aliasing packages by assigning to globs [perl #77358]
       Deleting packages by deleting their containing stash elements
       Undefining the glob containing a package ("undef *Foo::")
       Undefining an ISA glob ("undef *Foo::ISA")
       Deleting an ISA stash element ("delete $Foo::{ISA}")
       Sharing @ISA arrays between classes (via "*Foo::ISA = \@Bar::ISA"
       or "*Foo::ISA = *Bar::ISA") [perl #77238]

       "undef *Foo::ISA" would even stop a new @Foo::ISA array from
       updating caches.

   *   Typeglob assignments would crash if the glob's stash no longer
       existed, so long as the glob assigned to were named "ISA" or the
       glob on either side of the assignment contained a subroutine.

   *   "PL_isarev", which is accessible to Perl via "mro::get_isarev" is
       now updated properly when packages are deleted or removed from the
       @ISA of other classes.  This allows many packages to be created and
       deleted without causing a memory leak [perl #75176].

   In addition, various other bugs related to typeglobs and stashes have
   been fixed:

   *   Some work has been done on the internal pointers that link between
       symbol tables (stashes), typeglobs, and subroutines.  This has the
       effect that various edge cases related to deleting stashes or stash
       entries (for example, <%FOO:: = ()>), and complex typeglob or code-
       reference aliasing, will no longer crash the interpreter.

   *   Assigning a reference to a glob copy now assigns to a glob slot
       instead of overwriting the glob with a scalar [perl #1804] [perl

   *   A bug when replacing the glob of a loop variable within the loop
       has been fixed [perl #21469].  This means the following code will
       no longer crash:

           for $x (...) {
               *x = *y;

   *   Assigning a glob to a PVLV used to convert it to a plain string.
       Now it works correctly, and a PVLV can hold a glob.  This would
       happen when a nonexistent hash or array element was passed to a

         sub { $_[0] = *foo }->($hash{key});
         # $_[0] would have been the string "*main::foo"

       It also happened when a glob was assigned to, or returned from, an
       element of a tied array or hash [perl #36051].

   *   When trying to report "Use of uninitialized value $Foo::BAR",
       crashes could occur if the glob holding the global variable in
       question had been detached from its original stash by, for example,
       "delete $::{"Foo::"}".  This has been fixed by disabling the
       reporting of variable names in those cases.

   *   During the restoration of a localised typeglob on scope exit, any
       destructors called as a result would be able to see the typeglob in
       an inconsistent state, containing freed entries, which could result
       in a crash.  This would affect code like this:

         local *@;
         eval { die bless [] }; # puts an object in $@
         sub DESTROY {
           local $@; # boom

       Now the glob entries are cleared before any destructors are called.
       This also means that destructors can vivify entries in the glob.
       So Perl tries again and, if the entries are re-created too many
       times, dies with a "panic: gp_free ..." error message.

   *   If a typeglob is freed while a subroutine attached to it is still
       referenced elsewhere, the subroutine is renamed to "__ANON__" in
       the same package, unless the package has been undefined, in which
       case the "__ANON__" package is used.  This could cause packages to
       be sometimes autovivified, such as if the package had been deleted.
       Now this no longer occurs.  The "__ANON__" package is also now used
       when the original package is no longer attached to the symbol
       table.  This avoids memory leaks in some cases [perl #87664].

   *   Subroutines and package variables inside a package whose name ends
       with "::" can now be accessed with a fully qualified name.

   *   What has become known as "the Unicode Bug" is almost completely
       resolved in this release.  Under "use feature 'unicode_strings'"
       (which is automatically selected by "use 5.012" and above), the
       internal storage format of a string no longer affects the external
       semantics.  [perl #58182].

       There are two known exceptions:

       1.  The now-deprecated, user-defined case-changing functions
           require utf8-encoded strings to operate.  The CPAN module
           Unicode::Casing has been written to replace this feature
           without its drawbacks, and the feature is scheduled to be
           removed in 5.16.

       2.  quotemeta() (and its in-line equivalent "\Q") can also give
           different results depending on whether a string is encoded in
           UTF-8.  See "The "Unicode Bug"" in perlunicode.

   *   Handling of Unicode non-character code points has changed.
       Previously they were mostly considered illegal, except that in some
       place only one of the 66 of them was known.  The Unicode Standard
       considers them all legal, but forbids their "open interchange".
       This is part of the change to allow internal use of any code point
       (see "Core Enhancements").  Together, these changes resolve [perl
       #38722], [perl #51918], [perl #51936], and [perl #63446].

   *   Case-insensitive "/i" regular expression matching of Unicode
       characters that match multiple characters now works much more as
       intended.  For example

        "\N{LATIN SMALL LIGATURE FFI}" =~ /ffi/ui


        "ffi" =~ /\N{LATIN SMALL LIGATURE FFI}/ui

       are both true.  Previously, there were many bugs with this feature.
       What hasn't been fixed are the places where the pattern contains
       the multiple characters, but the characters are split up by other
       things, such as in

        "\N{LATIN SMALL LIGATURE FFI}" =~ /(f)(f)i/ui


        "\N{LATIN SMALL LIGATURE FFI}" =~ /ffi*/ui


        "\N{LATIN SMALL LIGATURE FFI}" =~ /[a-f][f-m][g-z]/ui

       None of these match.

       Also, this matching doesn't fully conform to the current Unicode
       Standard, which asks that the matching be made upon the NFD
       (Normalization Form Decomposed) of the text.  However, as of this
       writing (April 2010), the Unicode Standard is currently in flux
       about what they will recommend doing with regard in such scenarios.
       It may be that they will throw out the whole concept of multi-
       character matches.  [perl #71736].

   *   Naming a deprecated character in "\N{NAME}" no longer leaks memory.

   *   We fixed a bug that could cause "\N{NAME}" constructs followed by a
       single "." to be parsed incorrectly [perl #74978] (5.12.1).

   *   "chop" now correctly handles characters above "\x{7fffffff}" [perl

   *   Passing to "index" an offset beyond the end of the string when the
       string is encoded internally in UTF8 no longer causes panics [perl

   *   warn() and die() now respect utf8-encoded scalars [perl #45549].

   *   Sometimes the UTF8 length cache would not be reset on a value
       returned by substr, causing "length(substr($uni_string, ...))" to
       give wrong answers.  With "${^UTF8CACHE}" set to -1, it would also
       produce a "panic" error message [perl #77692].

   Ties, Overloading and Other Magic
   *   Overloading now works properly in conjunction with tied variables.
       What formerly happened was that most ops checked their arguments
       for overloading before checking for magic, so for example an
       overloaded object returned by a tied array access would usually be
       treated as not overloaded [RT #57012].

   *   Various instances of magic (like tie methods) being called on tied
       variables too many or too few times have been fixed:

       *   "$tied->()" did not always call FETCH [perl #8438].

       *   Filetest operators and "y///" and "tr///" were calling FETCH
           too many times.

       *   The "=" operator used to ignore magic on its right-hand side if
           the scalar happened to hold a typeglob (if a typeglob was the
           last thing returned from or assigned to a tied scalar) [perl

       *   Dereference operators used to ignore magic if the argument was
           a reference already (such as from a previous FETCH) [perl

       *   "splice" now calls set-magic (so changes made by "splice @ISA"
           are respected by method calls) [perl #78400].

       *   In-memory files created by "open($fh, ">", \$buffer)" were not
           calling FETCH/STORE at all [perl #43789] (5.12.2).

       *   utf8::is_utf8() now respects get-magic (like $1) (5.12.1).

   *   Non-commutative binary operators used to swap their operands if the
       same tied scalar was used for both operands and returned a
       different value for each FETCH.  For instance, if $t returned 2 the
       first time and 3 the second, then "$t/$t" would evaluate to 1.5.
       This has been fixed [perl #87708].

   *   String "eval" now detects taintedness of overloaded or tied
       arguments [perl #75716].

   *   String "eval" and regular expression matches against objects with
       string overloading no longer cause memory corruption or crashes
       [perl #77084].

   *   readline now honors "<>" overloading on tied arguments.

   *   "<expr>" always respects overloading now if the expression is

       Because "<>as glob" was parsed differently from "<>as filehandle"
       from 5.6 onwards, something like "<$foo[0]>" did not handle
       overloading, even if $foo[0] was an overloaded object.  This was
       contrary to the documentation for overload, and meant that "<>"
       could not be used as a general overloaded iterator operator.

   *   The fallback behaviour of overloading on binary operators was
       asymmetric [perl #71286].

   *   Magic applied to variables in the main package no longer affects
       other packages.  See "Magic variables outside the main package"
       above [perl #76138].

   *   Sometimes magic (ties, taintedness, etc.) attached to variables
       could cause an object to last longer than it should, or cause a
       crash if a tied variable were freed from within a tie method.
       These have been fixed [perl #81230].

   *   DESTROY methods of objects implementing ties are no longer able to
       crash by accessing the tied variable through a weak reference [perl

   *   Fixed a regression of kill() when a match variable is used for the
       process ID to kill [perl #75812].

   *   $AUTOLOAD used to remain tainted forever if it ever became tainted.
       Now it is correctly untainted if an autoloaded method is called and
       the method name was not tainted.

   *   "sprintf" now dies when passed a tainted scalar for the format.  It
       did already die for arbitrary expressions, but not for simple
       scalars [perl #82250].

   *   "lc", "uc", "lcfirst", and "ucfirst" no longer return untainted
       strings when the argument is tainted.  This has been broken since
       perl 5.8.9 [perl #87336].

   The Debugger
   *   The Perl debugger now also works in taint mode [perl #76872].

   *   Subroutine redefinition works once more in the debugger [perl

   *   When -d is used on the shebang ("#!") line, the debugger now has
       access to the lines of the main program.  In the past, this
       sometimes worked and sometimes did not, depending on the order in
       which things happened to be arranged in memory [perl #71806].

   *   A possible memory leak when using caller() to set @DB::args has
       been fixed (5.12.2).

   *   Perl no longer stomps on $DB::single, $DB::trace, and $DB::signal
       if these variables already have values when $^P is assigned to
       [perl #72422].

   *   "#line" directives in string evals were not properly updating the
       arrays of lines of code ("@{"_< ..."}") that the debugger (or any
       debugging or profiling module) uses.  In threaded builds, they were
       not being updated at all.  In non-threaded builds, the line number
       was ignored, so any change to the existing line number would cause
       the lines to be misnumbered [perl #79442].

   *   Perl no longer accidentally clones lexicals in scope within active
       stack frames in the parent when creating a child thread [perl

   *   Several memory leaks in cloning and freeing threaded Perl
       interpreters have been fixed [perl #77352].

   *   Creating a new thread when directory handles were open used to
       cause a crash, because the handles were not cloned, but simply
       passed to the new thread, resulting in a double free.

       Now directory handles are cloned properly on Windows and on systems
       that have a "fchdir" function.  On other systems, new threads
       simply do not inherit directory handles from their parent threads
       [perl #75154].

   *   The typeglob "*,", which holds the scalar variable $, (output field
       separator), had the wrong reference count in child threads.

   *   [perl #78494] When pipes are shared between threads, the "close"
       function (and any implicit close, such as on thread exit) no longer

   *   Perl now does a timely cleanup of SVs that are cloned into a new
       thread but then discovered to be orphaned (that is, their owners
       are not cloned).  This eliminates several "scalars leaked" warnings
       when joining threads.

   Scoping and Subroutines
   *   Lvalue subroutines are again able to return copy-on-write scalars.
       This had been broken since version 5.10.0 [perl #75656] (5.12.3).

   *   "require" no longer causes "caller" to return the wrong file name
       for the scope that called "require" and other scopes higher up that
       had the same file name [perl #68712].

   *   "sort" with a "($$)"-prototyped comparison routine used to cause
       the value of @_ to leak out of the sort.  Taking a reference to @_
       within the sorting routine could cause a crash [perl #72334].

   *   Match variables (like $1) no longer persist between calls to a sort
       subroutine [perl #76026].

   *   Iterating with "foreach" over an array returned by an lvalue sub
       now works [perl #23790].

   *   $@ is now localised during calls to "binmode" to prevent action at
       a distance [perl #78844].

   *   Calling a closure prototype (what is passed to an attribute handler
       for a closure) now results in a "Closure prototype called" error
       message instead of a crash [perl #68560].

   *   Mentioning a read-only lexical variable from the enclosing scope in
       a string "eval" no longer causes the variable to become writable
       [perl #19135].

   *   Within signal handlers, $! is now implicitly localized.

   *   CHLD signals are no longer unblocked after a signal handler is
       called if they were blocked before by "POSIX::sigprocmask" [perl

   *   A signal handler called within a signal handler could cause leaks
       or double-frees.  Now fixed [perl #76248].

   Miscellaneous Memory Leaks
   *   Several memory leaks when loading XS modules were fixed (5.12.2).

   *   substr(), pos(), keys(), and vec() could, when used in combination
       with lvalues, result in leaking the scalar value they operate on,
       and cause its destruction to happen too late.  This has now been

   *   The postincrement and postdecrement operators, "++" and "--", used
       to cause leaks when used on references.  This has now been fixed.

   *   Nested "map" and "grep" blocks no longer leak memory when
       processing large lists [perl #48004].

   *   "use VERSION" and "no VERSION" no longer leak memory [perl #78436]
       [perl #69050].

   *   ".=" followed by "<>" or "readline" would leak memory if $/
       contained characters beyond the octet range and the scalar assigned
       to happened to be encoded as UTF8 internally [perl #72246].

   *   "eval 'BEGIN{die}'" no longer leaks memory on non-threaded builds.

   Memory Corruption and Crashes
   *   glob() no longer crashes when %File::Glob:: is empty and
       "CORE::GLOBAL::glob" isn't present [perl #75464] (5.12.2).

   *   readline() has been fixed when interrupted by signals so it no
       longer returns the "same thing" as before or random memory.

   *   When assigning a list with duplicated keys to a hash, the
       assignment used to return garbage and/or freed values:

           @a = %h = (list with some duplicate keys);

       This has now been fixed [perl #31865].

   *   The mechanism for freeing objects in globs used to leave dangling
       pointers to freed SVs, meaning Perl users could see corrupted state
       during destruction.

       Perl now frees only the affected slots of the GV, rather than
       freeing the GV itself.  This makes sure that there are no dangling
       refs or corrupted state during destruction.

   *   The interpreter no longer crashes when freeing deeply-nested arrays
       of arrays.  Hashes have not been fixed yet [perl #44225].

   *   Concatenating long strings under "use encoding" no longer causes
       Perl to crash [perl #78674].

   *   Calling "->import" on a class lacking an import method could
       corrupt the stack, resulting in strange behaviour.  For instance,

         push @a, "foo", $b = bar->import;

       would assign "foo" to $b [perl #63790].

   *   The "recv" function could crash when called with the MSG_TRUNC flag
       [perl #75082].

   *   "formline" no longer crashes when passed a tainted format picture.
       It also taints $^A now if its arguments are tainted [perl #79138].

   *   A bug in how we process filetest operations could cause a segfault.
       Filetests don't always expect an op on the stack, so we now use
       TOPs only if we're sure that we're not "stat"ing the "_"
       filehandle.  This is indicated by "OPf_KIDS" (as checked in
       ck_ftst) [perl #74542] (5.12.1).

   *   unpack() now handles scalar context correctly for %32H and %32u,
       fixing a potential crash.  split() would crash because the third
       item on the stack wasn't the regular expression it expected.
       "unpack("%2H", ...)" would return both the unpacked result and the
       checksum on the stack, as would "unpack("%2u", ...)" [perl #73814]

   Fixes to Various Perl Operators
   *   The "&", "|", and "^" bitwise operators no longer coerce read-only
       arguments [perl #20661].

   *   Stringifying a scalar containing "-0.0" no longer has the effect of
       turning false into true [perl #45133].

   *   Some numeric operators were converting integers to floating point,
       resulting in loss of precision on 64-bit platforms [perl #77456].

   *   sprintf() was ignoring locales when called with constant arguments
       [perl #78632].

   *   Combining the vector (%v) flag and dynamic precision would cause
       "sprintf" to confuse the order of its arguments, making it treat
       the string as the precision and vice-versa [perl #83194].

   Bugs Relating to the C API
   *   The C-level "lex_stuff_pvn" function would sometimes cause a
       spurious syntax error on the last line of the file if it lacked a
       final semicolon [perl #74006] (5.12.1).

   *   The "eval_sv" and "eval_pv" C functions now set $@ correctly when
       there is a syntax error and no "G_KEEPERR" flag, and never set it
       if the "G_KEEPERR" flag is present [perl #3719].

   *   The XS multicall API no longer causes subroutines to lose reference
       counts if called via the multicall interface from within those very
       subroutines.  This affects modules like List::Util.  Calling one of
       its functions with an active subroutine as the first argument could
       cause a crash [perl #78070].

   *   The "SvPVbyte" function available to XS modules now calls magic
       before downgrading the SV, to avoid warnings about wide characters
       [perl #72398].

   *   The ref types in the typemap for XS bindings now support magical
       variables [perl #72684].

   *   "sv_catsv_flags" no longer calls "mg_get" on its second argument
       (the source string) if the flags passed to it do not include
       SV_GMAGIC.  So it now matches the documentation.

   *   "my_strftime" no longer leaks memory.  This fixes a memory leak in
       "POSIX::strftime" [perl #73520].

   *   XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS [perl
       #55049] (5.12.1).

   *   XS code using fputc() or fputs() on Windows could cause an error
       due to their arguments being swapped [perl #72704] (5.12.1).

   *   A possible segfault in the "T_PTROBJ" default typemap has been
       fixed (5.12.2).

   *   A bug that could cause "Unknown error" messages when "call_sv(code,
       G_EVAL)" is called from an XS destructor has been fixed (5.12.2).

Known Problems

   This is a list of significant unresolved issues which are regressions
   from earlier versions of Perl or which affect widely-used CPAN modules.

   *   "List::Util::first" misbehaves in the presence of a lexical $_
       (typically introduced by "my $_" or implicitly by "given").  The
       variable that gets set for each iteration is the package variable
       $_, not the lexical $_.

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

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

       See also: <>

   *   readline() returns an empty string instead of a cached previous
       value when it is interrupted by a signal

   *   The changes in prototype handling break Switch.  A patch has been
       sent upstream and will hopefully appear on CPAN soon.

   *   The upgrade to ExtUtils-MakeMaker-6.57_05 has caused some tests in
       the Module-Install distribution on CPAN to fail. (Specifically,
       02_mymeta.t tests 5 and 21; 18_all_from.t tests 6 and 15;
       19_authors.t tests 5, 13, 21, and 29; and
       20_authors_with_special_characters.t tests 6, 15, and 23 in version
       1.00 of that distribution now fail.)

   *   On VMS, "Time::HiRes" tests will fail due to a bug in the CRTL's
       implementation of "setitimer": previous timer values would be
       cleared if a timer expired but not if the timer was reset before
       expiring.  HP OpenVMS Engineering have corrected the problem and
       will release a patch in due course (Quix case # QXCM1001115136).

   *   On VMS, there were a handful of "Module::Build" test failures we
       didn't get to before the release; please watch CPAN for updates.


   keys(), values(), and each() work on arrays
   You can now use the keys(), values(), and each() builtins on arrays;
   previously you could use them only on hashes.  See perlfunc for
   details.  This is actually a change introduced in perl 5.12.0, but it
   was missed from that release's perl5120delta.

   split() and @_
   split() no longer modifies @_ when called in scalar or void context.
   In void context it now produces a "Useless use of split" warning.  This
   was also a perl 5.12.0 change that missed the perldelta.


   Randy Kobes, creator of and
   contributor/maintainer to several core Perl toolchain modules, passed
   away on September 18, 2010 after a battle with lung cancer.  The
   community was richer for his involvement.  He will be missed.


   Perl 5.14.0 represents one year of development since Perl 5.12.0 and
   contains nearly 550,000 lines of changes across nearly 3,000 files from
   150 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 5.14.0:

   Aaron Crane, Abhijit Menon-Sen, Abigail, var Arnfjr Bjarmason,
   Alastair Douglas, Alexander Alekseev, Alexander Hartmaier, Alexandr
   Ciornii, Alex Davies, Alex Vandiver, Ali Polatel, Allen Smith, Andreas
   Knig, Andrew Rodland, Andy Armstrong, Andy Dougherty, Aristotle
   Pagaltzis, Arkturuz, Arvan, A. Sinan Unur, Ben Morrow, Bo Lindbergh,
   Boris Ratner, Brad Gilbert, Bram, brian d foy, Brian Phillips, Casey
   West, Charles Bailey, Chas. Owens, Chip Salzenberg, Chris 'BinGOs'
   Williams, chromatic, Craig A. Berry, Curtis Jewell, Dagfinn Ilmari
   Mannsker, Dan Dascalescu, Dave Rolsky, David Caldwell, David Cantrell,
   David Golden, David Leadbeater, David Mitchell, David Wheeler, Eric
   Brine, Father Chrysostomos, Fingle Nark, Florian Ragwitz, Frank
   Wiegand, Franz Fasching, Gene Sullivan, George Greer, Gerard Goossen,
   Gisle Aas, Goro Fuji, Grant McLean, gregor herrmann, H.Merijn Brand,
   Hongwen Qiu, Hugo van der Sanden, Ian Goodacre, James E Keenan, James
   Mastros, Jan Dubois, Jay Hannah, Jerry D. Hedden, Jesse Vincent, Jim
   Cromie, Jirka Hruka, John Peacock, Joshua ben Jore, Joshua Pritikin,
   Karl Williamson, Kevin Ryde, kmx, Lars D , Larwan Berke,
   Leon Brocard, Leon Timmermans, Lubomir Rintel, Lukas Mai, Maik
   Hentsche, Marty Pauley, Marvin Humphrey, Matt Johnson, Matt S Trout,
   Max Maischein, Michael Breen, Michael Fig, Michael G Schwern, Michael
   Parker, Michael Stevens, Michael Witten, Mike Kelly, Moritz Lenz,
   Nicholas Clark, Nick Cleaton, Nick Johnston, Nicolas Kaiser, Niko Tyni,
   Noirin Shirley, Nuno Carvalho, Paul Evans, Paul Green, Paul Johnson,
   Paul Marquess, Peter J. Holzer, Peter John Acklam, Peter Martini,
   Philippe Bruhat (BooK), Piotr Fusik, Rafael Garcia-Suarez, Rainer
   Tammer, Reini Urban, Renee Baecker, Ricardo Signes, Richard Mhn,
   Richard Soderberg, Rob Hoelz, Robin Barker, Ruslan Zakirov, Salvador
   Fandio, Salvador Ortiz Garcia, Shlomi Fish, Sinan Unur, Sisyphus,
   Slaven Rezic, Steffen Mller, Steve Hay, Steven Schubiger, Steve
   Peters, Sullivan Beck, Tatsuhiko Miyagawa, Tim Bunce, Todd Rinaldo, Tom
   Christiansen, Tom Hukins, Tony Cook, Tye McQueen, Vadim Konovalov,
   Vernon Lyon, Vincent Pit, Walt Mankowski, Wolfram Humann, Yves Orton,
   Zefram, and Zsbn 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 5.14.0 better. For a
   more complete list of all of Perl's historical contributors, please see
   the "AUTHORS" file in the Perl 5.14.0 distribution.

   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 analysed by
   the Perl porting team.

   If the bug you are reporting has security implications, which make it
   inappropriate to send to a publicly archived mailing list, then please
   send it to  This points to a closed
   subscription unarchived mailing list, which includes all the core
   committers, who are 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 use this address for security issues in the Perl
   core only, not for modules independently distributed on CPAN.


   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.

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The user session keyring is a keyring used to anchor keys on behalf of a user. Each UID the kernel deals with has its own user session keyring. This keyring is

Tcl_Import(3) - manipulate namespaces - Linux manual page...
Namespaces are hierarchic naming contexts that can contain commands and variables. They also maintain a list of patterns that describes what commands are export

semget(2) - get a semaphore set identifier - Linux man page
The semget() system call returns the System V semaphore set identifier associated with the argument key. A new set of nsems semaphores is created if key has the

ber_bvdup(3) - OpenLDAP LBER types and allocation functions
The following are the basic types and structures defined for use with the Lightweight BER library. ber_int_t is a signed integer of at least 32 bits. It is comm

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