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PERL5160DELTA(1)                           Perl Programmers Reference Guide                          PERL5160DELTA(1)



NAME
       perl5160delta - what is new for perl v5.16.0

DESCRIPTION
       This document describes differences between the 5.14.0 release and the 5.16.0 release.

       If you are upgrading from an earlier release such as 5.12.0, first read perl5140delta, which describes
       differences between 5.12.0 and 5.14.0.

       Some bug fixes in this release have been backported to later releases of 5.14.x.  Those are indicated with the
       5.14.x version in parentheses.

Notice
       With the release of Perl 5.16.0, the 5.12.x series of releases is now out of its support period.  There may be
       future 5.12.x releases, but only in the event of a critical security issue.  Users of Perl 5.12 or earlier
       should consider upgrading to a more recent release of Perl.

       This policy is described in greater detail in perlpolicy.

Core Enhancements
   "use VERSION"
       As of this release, version declarations like "use v5.16" now disable all features before enabling the new
       feature bundle.  This means that the following holds true:

           use 5.016;
           # only 5.16 features enabled here
           use 5.014;
           # only 5.14 features enabled here (not 5.16)

       "use v5.12" and higher continue to enable strict, but explicit "use strict" and "no strict" now override the
       version declaration, even when they come first:

           no strict;
           use 5.012;
           # no strict here

       There is a new ":default" feature bundle that represents the set of features enabled before any version
       declaration or "use feature" has been seen.  Version declarations below 5.10 now enable the ":default" feature
       set.  This does not actually change the behavior of "use v5.8", because features added to the ":default" set
       are those that were traditionally enabled by default, before they could be turned off.

       "no feature" now resets to the default feature set.  To disable all features (which is likely to be a pretty
       special-purpose request, since it presumably won't match any named set of semantics) you can now write "no
       feature ':all'".

       $[ is now disabled under "use v5.16".  It is part of the default feature set and can be turned on or off
       explicitly with "use feature 'array_base'".

   "__SUB__"
       The new "__SUB__" token, available under the "current_sub" feature (see feature) or "use v5.16", returns a
       reference to the current subroutine, making it easier to write recursive closures.

   New and Improved Built-ins
       More consistent "eval"

       The "eval" operator sometimes treats a string argument as a sequence of characters and sometimes as a sequence

       When "substr" is called in lvalue or potential lvalue context with two or three arguments, a special lvalue
       scalar is returned that modifies the original string (the first argument) when assigned to.

       Previously, the offsets (the second and third arguments) passed to "substr" would be converted immediately to
       match the string, negative offsets being translated to positive and offsets beyond the end of the string being
       truncated.

       Now, the offsets are recorded without modification in the special lvalue scalar that is returned, and the
       original string is not even looked at by "substr" itself, but only when the returned lvalue is read or
       modified.

       These changes result in an incompatible change:

       If the original string changes length after the call to "substr" but before assignment to its return value,
       negative offsets will remember their position from the end of the string, affecting code like this:

           my $string = "string";
           my $lvalue = \substr $string, -4, 2;
           print $$lvalue, "\n"; # prints "ri"
           $string = "bailing twine";
           print $$lvalue, "\n"; # prints "wi"; used to print "il"

       The same thing happens with an omitted third argument.  The returned lvalue will always extend to the end of
       the string, even if the string becomes longer.

       Since this change also allowed many bugs to be fixed (see "The "substr" operator"), and since the behavior of
       negative offsets has never been specified, the change was deemed acceptable.

       Return value of "tied"

       The value returned by "tied" on a tied variable is now the actual scalar that holds the object to which the
       variable is tied.  This lets ties be weakened with "Scalar::Util::weaken(tied $tied_variable)".

   Unicode Support
       Supports (almost) Unicode 6.1

       Besides the addition of whole new scripts, and new characters in existing scripts, this new version of
       Unicode, as always, makes some changes to existing characters.  One change that may trip up some applications
       is that the General Category of two characters in the Latin-1 range, PILCROW SIGN and SECTION SIGN, has been
       changed from Other_Symbol to Other_Punctuation.  The same change has been made for a character in each of
       Tibetan, Ethiopic, and Aegean.  The code points U+3248..U+324F (CIRCLED NUMBER TEN ON BLACK SQUARE through
       CIRCLED NUMBER EIGHTY ON BLACK SQUARE) have had their General Category changed from Other_Symbol to
       Other_Numeric.  The Line Break property has changes for Hebrew and Japanese; and because of other changes in
       6.1, the Perl regular expression construct "\X" now works differently for some characters in Thai and Lao.

       New aliases (synonyms) have been defined for many property values; these, along with the previously existing
       ones, are all cross-indexed in perluniprops.

       The return value of "charnames::viacode()" is affected by other changes:

        Code point      Old Name             New Name
          U+000A    LINE FEED (LF)        LINE FEED
          U+000C    FORM FEED (FF)        FORM FEED

       which conflicts with the longstanding industry use of (and Unicode's recommendation to use) that name to mean
       the ASCII control character at U+0007.  Therefore, that name has been deprecated in Perl since v5.14, and any
       use of it will raise a warning message (unless turned off).  The name "ALERT" is now the preferred name for
       this code point, with "BEL" an acceptable short form.  The name for the new cell phone character, at code
       point U+1F514, remains undefined in this version of Perl (hence we don't implement quite all of Unicode 6.1),
       but starting in v5.18, BELL will mean this character, and not U+0007.

       Unicode has taken steps to make sure that this sort of mistake does not happen again.  The Standard now
       includes all generally accepted names and abbreviations for control characters, whereas previously it didn't
       (though there were recommended names for most of them, which Perl used).  This means that most of those
       recommended names are now officially in the Standard.  Unicode did not recommend names for the four code
       points listed above between U+008E and U+008F, and in standardizing them Unicode subtly changed the names that
       Perl had previously given them, by replacing the final blank in each name by a hyphen.  Unicode also
       officially accepts names that Perl had deprecated, such as FILE SEPARATOR.  Now the only deprecated name is
       BELL.  Finally, Perl now uses the new official names instead of the old (now considered obsolete) names for
       the first four code points in the list above (the ones which have the parentheses in them).

       Now that the names have been placed in the Unicode standard, these kinds of changes should not happen again,
       though corrections, such as to U+2118, are still possible.

       Unicode also added some name abbreviations, which Perl now accepts: SP for SPACE; TAB for CHARACTER
       TABULATION; NEW LINE, END OF LINE, NL, and EOL for LINE FEED; LOCKING-SHIFT ONE for SHIFT OUT; LOCKING-SHIFT
       ZERO for SHIFT IN; and ZWNBSP for ZERO WIDTH NO-BREAK SPACE.

       More details on this version of Unicode are provided in <http://www.unicode.org/versions/Unicode6.1.0/>.

       "use charnames" is no longer needed for "\N{name}"

       When "\N{name}" is encountered, the "charnames" module is now automatically loaded when needed as if the
       ":full" and ":short" options had been specified.  See charnames for more information.

       "\N{...}" can now have Unicode loose name matching

       This is described in the "charnames" item in "Updated Modules and Pragmata" below.

       Unicode Symbol Names

       Perl now has proper support for Unicode in symbol names.  It used to be that "*{$foo}" would ignore the
       internal UTF8 flag and use the bytes of the underlying representation to look up the symbol.  That meant that
       "*{"\x{100}"}" and "*{"\xc4\x80"}" would return the same thing.  All these parts of Perl have been fixed to
       account for Unicode:

       ·   Method names (including those passed to "use overload")

       ·   Typeglob names (including names of variables, subroutines, and filehandles)

       ·   Package names

       ·   "goto"

       ·   Symbolic dereferencing

       ·   Second argument to "bless()" and "tie()"

       all Unicode identifier characters.

       One-character non-ASCII non-punctuation variables (like "$e") are now subject to "Used only once" warnings.
       They used to be exempt, as they were treated as punctuation variables.

       Also, single-character Unicode punctuation variables (like $X) are now supported [perl #69032].

       Improved ability to mix locales and Unicode, including UTF-8 locales

       An optional parameter has been added to "use locale"

        use locale ':not_characters';

       which tells Perl to use all but the "LC_CTYPE" and "LC_COLLATE" portions of the current locale.  Instead, the
       character set is assumed to be Unicode.  This lets locales and Unicode be seamlessly mixed, including the
       increasingly frequent UTF-8 locales.  When using this hybrid form of locales, the ":locale" layer to the open
       pragma can be used to interface with the file system, and there are CPAN modules available for ARGV and
       environment variable conversions.

       Full details are in perllocale.

       New function "fc" and corresponding escape sequence "\F" for Unicode foldcase

       Unicode foldcase is an extension to lowercase that gives better results when comparing two strings case-
       insensitively.  It has long been used internally in regular expression "/i" matching.  Now it is available
       explicitly through the new "fc" function call (enabled by "use feature 'fc'", or "use v5.16", or explicitly
       callable via "CORE::fc") or through the new "\F" sequence in double-quotish strings.

       Full details are in "fc" in perlfunc.

       The Unicode "Script_Extensions" property is now supported.

       New in Unicode 6.0, this is an improved "Script" property.  Details are in "Scripts" in perlunicode.

   XS Changes
       Improved typemaps for Some Builtin Types

       Most XS authors will know there is a longstanding bug in the OUTPUT typemap for T_AVREF ("AV*"), T_HVREF
       ("HV*"), T_CVREF ("CV*"), and T_SVREF ("SVREF" or "\$foo") that requires manually decrementing the reference
       count of the return value instead of the typemap taking care of this.  For backwards-compatibility, this
       cannot be changed in the default typemaps.  But we now provide additional typemaps "T_AVREF_REFCOUNT_FIXED",
       etc. that do not exhibit this bug.  Using them in your extension is as simple as having one line in your
       "TYPEMAP" section:

         HV*   T_HVREF_REFCOUNT_FIXED

       "is_utf8_char()"

       The XS-callable function "is_utf8_char()", when presented with malformed UTF-8 input, can read up to 12 bytes
       beyond the end of the string.  This cannot be fixed without changing its API, and so its use is now
       deprecated.  Use "is_utf8_char_buf()" (described just below) instead.

       Added "is_utf8_char_buf()"

       Many new functions have been added to the API for manipulating lexical pads.  See "Pad Data Structures" in
       perlapi for more information.

   Changes to Special Variables
       $$ can be assigned to

       $$ was made read-only in Perl 5.8.0.  But only sometimes: "local $$" would make it writable again.  Some CPAN
       modules were using "local $$" or XS code to bypass the read-only check, so there is no reason to keep $$ read-
       only.  (This change also allowed a bug to be fixed while maintaining backward compatibility.)

       $^X converted to an absolute path on FreeBSD, OS X and Solaris

       $^X is now converted to an absolute path on OS X, FreeBSD (without needing /proc mounted) and Solaris 10 and
       11.  This augments the previous approach of using /proc on Linux, FreeBSD, and NetBSD (in all cases, where
       mounted).

       This makes relocatable perl installations more useful on these platforms.  (See "Relocatable @INC" in INSTALL)

   Debugger Changes
       Features inside the debugger

       The current Perl's feature bundle is now enabled for commands entered in the interactive debugger.

       New option for the debugger's t command

       The t command in the debugger, which toggles tracing mode, now accepts a numeric argument that determines how
       many levels of subroutine calls to trace.

       "enable" and "disable"

       The debugger now has "disable" and "enable" commands for disabling existing breakpoints and re-enabling them.
       See perldebug.

       Breakpoints with file names

       The debugger's "b" command for setting breakpoints now lets a line number be prefixed with a file name.  See
       "b [file]:[line] [condition]" in perldebug.

   The "CORE" Namespace
       The "CORE::" prefix

       The "CORE::" prefix can now be used on keywords enabled by feature.pm, even outside the scope of "use
       feature".

       Subroutines in the "CORE" namespace

       Many Perl keywords are now available as subroutines in the CORE namespace.  This lets them be aliased:

           BEGIN { *entangle = \&CORE::tie }
           entangle $variable, $package, @args;

       And for prototypes to be bypassed:

           sub mytie(\[%$*@]$@) {

       Automatically generated file handles are now named __ANONIO__ when the variable name cannot be determined,
       rather than $__ANONIO__.

       Autoloaded sort Subroutines

       Custom sort subroutines can now be autoloaded [perl #30661]:

           sub AUTOLOAD { ... }
           @sorted = sort foo @list; # uses AUTOLOAD

       "continue" no longer requires the "switch" feature

       The "continue" keyword has two meanings.  It can introduce a "continue" block after a loop, or it can exit the
       current "when" block.  Up to now, the latter meaning was valid only with the "switch" feature enabled, and was
       a syntax error otherwise.  Since the main purpose of feature.pm is to avoid conflicts with user-defined
       subroutines, there is no reason for "continue" to depend on it.

       DTrace probes for interpreter phase change

       The "phase-change" probes will fire when the interpreter's phase changes, which tracks the "${^GLOBAL_PHASE}"
       variable.  "arg0" is the new phase name; "arg1" is the old one.  This is useful for limiting your
       instrumentation to one or more of: compile time, run time, or destruct time.

       "__FILE__()" Syntax

       The "__FILE__", "__LINE__" and "__PACKAGE__" tokens can now be written with an empty pair of parentheses after
       them.  This makes them parse the same way as "time", "fork" and other built-in functions.

       The "\$" prototype accepts any scalar lvalue

       The "\$" and "\[$]" subroutine prototypes now accept any scalar lvalue argument.  Previously they accepted
       only scalars beginning with "$" and hash and array elements.  This change makes them consistent with the way
       the built-in "read" and "recv" functions (among others) parse their arguments.  This means that one can
       override the built-in functions with custom subroutines that parse their arguments the same way.

       "_" in subroutine prototypes

       The "_" character in subroutine prototypes is now allowed before "@" or "%".

Security
   Use "is_utf8_char_buf()" and not "is_utf8_char()"
       The latter function is now deprecated because its API is insufficient to guarantee that it doesn't read (up to
       12 bytes in the worst case) beyond the end of its input string.  See is_utf8_char_buf().

   Malformed UTF-8 input could cause attempts to read beyond the end of the buffer
       Two new XS-accessible functions, "utf8_to_uvchr_buf()" and "utf8_to_uvuni_buf()" are now available to prevent
       this, and the Perl core has been converted to use them.  See "Internal Changes".

   "File::Glob::bsd_glob()" memory error with GLOB_ALTDIRFUNC (CVE-2011-2728).
       Calling "File::Glob::bsd_glob" with the unsupported flag GLOB_ALTDIRFUNC would cause an access violation /
       segfault.  A Perl program that accepts a flags value from an external source could expose itself to denial of
       service or arbitrary code execution attacks.  There are no known exploits in the wild.  The problem has been
       corrected by explicitly disabling all unsupported flags and setting unused function pointers to null.  Bug
       reported by Clement Lecigne. (5.14.2)
       Perl may at some point in the future change or remove these files.  The file which applications were most
       likely to have used is lib/unicore/ToDigit.pl.  "prop_invmap()" in Unicode::UCD can be used to get at its data
       instead.

   XS functions "is_utf8_char()", "utf8_to_uvchr()" and "utf8_to_uvuni()"
       This function is deprecated because it could read beyond the end of the input string.  Use the new
       is_utf8_char_buf(), "utf8_to_uvchr_buf()" and "utf8_to_uvuni_buf()" instead.

Future Deprecations
       This section serves as a notice of features that are likely to be removed or deprecated in the next release of
       perl (5.18.0).  If your code depends on these features, you should contact the Perl 5 Porters via the mailing
       list <http://lists.perl.org/list/perl5-porters.html> or perlbug to explain your use case and inform the
       deprecation process.

   Core Modules
       These modules may be marked as deprecated from the core.  This only means that they will no longer be
       installed by default with the core distribution, but will remain available on the CPAN.

       ·   CPANPLUS

       ·   Filter::Simple

       ·   PerlIO::mmap

       ·   Pod::LaTeX

       ·   Pod::Parser

       ·   SelfLoader

       ·   Text::Soundex

       ·   Thread.pm

   Platforms with no supporting programmers:
       These platforms will probably have their special build support removed during the 5.17.0 development series.

       ·   BeOS

       ·   djgpp

       ·   dgux

       ·   EPOC

       ·   MPE/iX

       ·   Rhapsody

       ·   UTS

       ·   VM/ESA

   Other Future Deprecations

       ·   Unescaped literal "{" in regular expressions.

           Starting with v5.20, it is planned to require a literal "{" to be escaped, for example by preceding it
           with a backslash.  In v5.18, a deprecated warning message will be emitted for all such uses.  This affects
           only patterns that are to match a literal "{".  Other uses of this character, such as part of a quantifier
           or sequence as in those below, are completely unaffected:

               /foo{3,5}/
               /\p{Alphabetic}/
               /\N{DIGIT ZERO}

           Removing this will permit extensions to Perl's pattern syntax and better error checking for existing
           syntax.  See "Quantifiers" in perlre for an example.

       ·   Revamping "\Q" semantics in double-quotish strings when combined with other escapes.

           There are several bugs and inconsistencies involving combinations of "\Q" and escapes like "\x", "\L",
           etc., within a "\Q...\E" pair.  These need to be fixed, and doing so will necessarily change current
           behavior.  The changes have not yet been settled.

Incompatible Changes
   Special blocks called in void context
       Special blocks ("BEGIN", "CHECK", "INIT", "UNITCHECK", "END") are now called in void context.  This avoids
       wasteful copying of the result of the last statement [perl #108794].

   The "overloading" pragma and regexp objects
       With "no overloading", regular expression objects returned by "qr//" are now stringified as
       "Regexp=REGEXP(0xbe600d)" instead of the regular expression itself [perl #108780].

   Two XS typemap Entries removed
       Two presumably unused XS typemap entries have been removed from the core typemap: T_DATAUNIT and T_CALLBACK.
       If you are, against all odds, a user of these, please see the instructions on how to restore them in
       perlxstypemap.

   Unicode 6.1 has incompatibilities with Unicode 6.0
       These are detailed in "Supports (almost) Unicode 6.1" above.  You can compile this version of Perl to use
       Unicode 6.0.  See "Hacking Perl to work on earlier Unicode versions (for very serious hackers only)" in
       perlunicode.

   Borland compiler
       All support for the Borland compiler has been dropped.  The code had not worked for a long time anyway.

   Certain deprecated Unicode properties are no longer supported by default
       Perl should never have exposed certain Unicode properties that are used by Unicode internally and not meant to
       be publicly available.  Use of these has generated deprecated warning messages since Perl 5.12.  The removed
       properties are Other_Alphabetic, Other_Default_Ignorable_Code_Point, Other_Grapheme_Extend, Other_ID_Continue,
       Other_ID_Start, Other_Lowercase, Other_Math, and Other_Uppercase.

       Perl may be recompiled to include any or all of them; instructions are given in "Unicode character properties
       that are NOT accepted by Perl" in perluniprops.

   Dereferencing IO thingies as typeglobs
       The "*{...}" operator, when passed a reference to an IO thingy (as in "*{*STDIN{IO}}"), creates a new typeglob
       containing just that IO object.  Previously, it would stringify as an empty string, but some operators would
       the XS compiler, ExtUtils::ParseXS ("xsubpp") will emit 'static' XSUBs by default.  ExtUtils::ParseXS's
       behavior can be reconfigured from XS using the "EXPORT_XSUB_SYMBOLS" keyword.  See perlxs for details.

   Weakening read-only references
       Weakening read-only references is no longer permitted.  It should never have worked anyway, and could
       sometimes result in crashes.

   Tying scalars that hold typeglobs
       Attempting to tie a scalar after a typeglob was assigned to it would instead tie the handle in the typeglob's
       IO slot.  This meant that it was impossible to tie the scalar itself.  Similar problems affected "tied" and
       "untie": "tied $scalar" would return false on a tied scalar if the last thing returned was a typeglob, and
       "untie $scalar" on such a tied scalar would do nothing.

       We fixed this problem before Perl 5.14.0, but it caused problems with some CPAN modules, so we put in a
       deprecation cycle instead.

       Now the deprecation has been removed and this bug has been fixed.  So "tie $scalar" will always tie the
       scalar, not the handle it holds.  To tie the handle, use "tie *$scalar" (with an explicit asterisk).  The same
       applies to "tied *$scalar" and "untie *$scalar".

   IPC::Open3 no longer provides "xfork()", "xclose_on_exec()" and "xpipe_anon()"
       All three functions were private, undocumented, and unexported.  They do not appear to be used by any code on
       CPAN.  Two have been inlined and one deleted entirely.

   $$ no longer caches PID
       Previously, if one called fork(3) from C, Perl's notion of $$ could go out of sync with what getpid() returns.
       By always fetching the value of $$ via getpid(), this potential bug is eliminated.  Code that depends on the
       caching behavior will break.  As described in Core Enhancements, $$ is now writable, but it will be reset
       during a fork.

   $$ and "getppid()" no longer emulate POSIX semantics under LinuxThreads
       The POSIX emulation of $$ and "getppid()" under the obsolete LinuxThreads implementation has been removed.
       This only impacts users of Linux 2.4 and users of Debian GNU/kFreeBSD up to and including 6.0, not the vast
       majority of Linux installations that use NPTL threads.

       This means that "getppid()", like $$, is now always guaranteed to return the OS's idea of the current state of
       the process, not perl's cached version of it.

       See the documentation for $$ for details.

   $<, $>, $( and $) are no longer cached
       Similarly to the changes to $$ and "getppid()", the internal caching of $<, $>, $( and $) has been removed.

       When we cached these values our idea of what they were would drift out of sync with reality if someone (e.g.,
       someone embedding perl) called "sete?[ug]id()" without updating "PL_e?[ug]id".  Having to deal with this
       complexity wasn't worth it given how cheap the "gete?[ug]id()" system call is.

       This change will break a handful of CPAN modules that use the XS-level "PL_uid", "PL_gid", "PL_euid" or
       "PL_egid" variables.

       The fix for those breakages is to use "PerlProc_gete?[ug]id()" to retrieve them (e.g., "PerlProc_getuid()"),
       and not to assign to "PL_e?[ug]id" if you change the UID/GID/EUID/EGID.  There is no longer any need to do so
       since perl will always retrieve the up-to-date version of those values from the OS.


           likely to be searched for.  A separate hash was used for each mention of a Unicode property in each
           regular expression.  Thus, "qr/\p{foo}abc\p{foo}/" would generate two hashes.  Any probes in one instance
           would be unknown to the other, and the hashes could expand separately to be quite large if the regular
           expression were used on many different widely-separated code points.  Now, however, there is just one hash
           shared by all instances of a given property.  This means that if "\p{foo}" is matched against "A" in one
           regular expression in a thread, the result will be known immediately to all regular expressions, and the
           relentless march of using up memory is slowed considerably.

       ·   Version declarations with the "use" keyword (e.g., "use 5.012") are now faster, as they enable features
           without loading feature.pm.

       ·   "local $_" is faster now, as it no longer iterates through magic that it is not going to copy anyway.

       ·   Perl 5.12.0 sped up the destruction of objects whose classes define empty "DESTROY" methods (to prevent
           autoloading), by simply not calling such empty methods.  This release takes this optimization a step
           further, by not calling any "DESTROY" method that begins with a "return" statement.  This can be useful
           for destructors that are only used for debugging:

               use constant DEBUG => 1;
               sub DESTROY { return unless DEBUG; ... }

           Constant-folding will reduce the first statement to "return;" if DEBUG is set to 0, triggering this
           optimization.

       ·   Assigning to a variable that holds a typeglob or copy-on-write scalar is now much faster.  Previously the
           typeglob would be stringified or the copy-on-write scalar would be copied before being clobbered.

       ·   Assignment to "substr" in void context is now more than twice its previous speed.  Instead of creating and
           returning a special lvalue scalar that is then assigned to, "substr" modifies the original string itself.

       ·   "substr" no longer calculates a value to return when called in void context.

       ·   Due to changes in File::Glob, Perl's "glob" function and its "<...>" equivalent are now much faster.  The
           splitting of the pattern into words has been rewritten in C, resulting in speed-ups of 20% for some cases.

           This does not affect "glob" on VMS, as it does not use File::Glob.

       ·   The short-circuiting operators "&&", "||", and "//", when chained (such as "$a || $b || $c"), are now
           considerably faster to short-circuit, due to reduced optree traversal.

       ·   The implementation of "s///r" makes one fewer copy of the scalar's value.

       ·   Recursive calls to lvalue subroutines in lvalue scalar context use less memory.

Modules and Pragmata
   Deprecated Modules
       Version::Requirements
           Version::Requirements is now DEPRECATED, use CPAN::Meta::Requirements, which is a drop-in replacement.  It
           will be deleted from perl.git blead in v5.17.0.

   New Modules and Pragmata
       ·   arybase -- this new module implements the $[ variable.

       ·   PerlIO::mmap 0.010 has been added to the Perl core.

           Includes a fix for FreeBSD to only use "unzip" if it is located in "/usr/local/bin", as FreeBSD 9.0 will
           ship with a limited "unzip" in "/usr/bin".

       ·   Archive::Tar has been upgraded from version 1.76 to 1.82.

           Adjustments to handle files >8gb (>0777777777777 octal) and a feature to return the MD5SUM of files in the
           archive.

       ·   base has been upgraded from version 2.16 to 2.18.

           "base" no longer sets a module's $VERSION to "-1" when a module it loads does not define a $VERSION.  This
           change has been made because "-1" is not a valid version number under the new "lax" criteria used
           internally by "UNIVERSAL::VERSION".  (See version for more on "lax" version criteria.)

           "base" no longer internally skips loading modules it has already loaded and instead relies on "require" to
           inspect %INC.  This fixes a bug when "base" is used with code that clear %INC to force a module to be
           reloaded.

       ·   Carp has been upgraded from version 1.20 to 1.26.

           It now includes last read filehandle info and puts a dot after the file and line number, just like errors
           from "die" [perl #106538].

       ·   charnames has been updated from version 1.18 to 1.30.

           "charnames" can now be invoked with a new option, ":loose", which is like the existing ":full" option, but
           enables Unicode loose name matching.  Details are in "LOOSE MATCHES" in charnames.

       ·   B::Deparse has been upgraded from version 1.03 to 1.14.  This fixes numerous deparsing bugs.

       ·   CGI has been upgraded from version 3.52 to 3.59.

           It uses the public and documented FCGI.pm API in CGI::Fast.  CGI::Fast was using an FCGI API that was
           deprecated and removed from documentation more than ten years ago.  Usage of this deprecated API with FCGI
           >= 0.70 or FCGI <= 0.73 introduces a security issue.
           <https://rt.cpan.org/Public/Bug/Display.html?id=68380>
           http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2011-2766
           <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2011-2766>

           Things that may break your code:

           "url()" was fixed to return "PATH_INFO" when it is explicitly requested with either the "path=>1" or
           "path_info=>1" flag.

           If your code is running under mod_rewrite (or compatible) and you are calling "self_url()" or you are
           calling "url()" and passing "path_info=>1", these methods will actually be returning "PATH_INFO" now, as
           you have explicitly requested or "self_url()" has requested on your behalf.

           The "PATH_INFO" has been omitted in such URLs since the issue was introduced in the 3.12 release in
           December, 2005.

           This bug is so old your application may have come to depend on it or workaround it. Check for application
           before upgrading to this release.

           In addition, the DELETE HTTP verb is now supported.

       ·   Compress::Zlib has been upgraded from version 2.035 to 2.048.

           IO::Compress::Zip and IO::Uncompress::Unzip now have support for LZMA (method 14).  There is a fix for a
           CRC issue in IO::Compress::Unzip and it supports Streamed Stored context now.  And fixed a Zip64 issue in
           IO::Compress::Zip when the content size was exactly 0xFFFFFFFF.

       ·   Digest::SHA has been upgraded from version 5.61 to 5.71.

           Added BITS mode to the addfile method and shasum.  This makes partial-byte inputs possible via files/STDIN
           and lets shasum check all 8074 NIST Msg vectors, where previously special programming was required to do
           this.

       ·   Encode has been upgraded from version 2.42 to 2.44.

           Missing aliases added, a deep recursion error fixed and various documentation updates.

           Addressed 'decode_xs n-byte heap-overflow' security bug in Unicode.xs (CVE-2011-2939). (5.14.2)

       ·   ExtUtils::CBuilder updated from version 0.280203 to 0.280206.

           The new version appends CFLAGS and LDFLAGS to their Config.pm counterparts.

       ·   ExtUtils::ParseXS has been upgraded from version 2.2210 to 3.16.

           Much of ExtUtils::ParseXS, the module behind the XS compiler "xsubpp", was rewritten and cleaned up.  It
           has been made somewhat more extensible and now finally uses strictures.

           The typemap logic has been moved into a separate module, ExtUtils::Typemaps.  See "New Modules and
           Pragmata", above.

           For a complete set of changes, please see the ExtUtils::ParseXS changelog, available on the CPAN.

       ·   File::Glob has been upgraded from version 1.12 to 1.17.

           On Windows, tilde (~) expansion now checks the "USERPROFILE" environment variable, after checking "HOME".

           It has a new ":bsd_glob" export tag, intended to replace ":glob".  Like ":glob" it overrides "glob" with a
           function that does not split the glob pattern into words, but, unlike ":glob", it iterates properly in
           scalar context, instead of returning the last file.

           There are other changes affecting Perl's own "glob" operator (which uses File::Glob internally, except on
           VMS).  See "Performance Enhancements" and "Selected Bug Fixes".

       ·   FindBin updated from version 1.50 to 1.51.

           It no longer returns a wrong result if a script of the same name as the current one exists in the path and
           is executable.

       ·   HTTP::Tiny has been upgraded from version 0.012 to 0.017.

           Added support for using $ENV{http_proxy} to set the default proxy host.

       ·   IPC::Cmd has been upgraded from version 0.70 to 0.76.

           Capturing of command output (both "STDOUT" and "STDERR") is now supported using IPC::Open3 on MSWin32
           without requiring IPC::Run.

       ·   IPC::Open3 has been upgraded from version 1.09 to 1.12.

           Fixes a bug which prevented use of "open3" on Windows when *STDIN, *STDOUT or *STDERR had been localized.

           Fixes a bug which prevented duplicating numeric file descriptors on Windows.

           "open3" with "-" for the program name works once more.  This was broken in version 1.06 (and hence in Perl
           5.14.0) [perl #95748].

       ·   Locale::Codes has been upgraded from version 3.16 to 3.21.

           Added Language Extension codes (langext) and Language Variation codes (langvar) as defined in the IANA
           language registry.

           Added language codes from ISO 639-5

           Added language/script codes from the IANA language subtag registry

           Fixed an uninitialized value warning [rt.cpan.org #67438].

           Fixed the return value for the all_XXX_codes and all_XXX_names functions [rt.cpan.org #69100].

           Reorganized modules to move Locale::MODULE to Locale::Codes::MODULE to allow for cleaner future additions.
           The original four modules (Locale::Language, Locale::Currency, Locale::Country, Locale::Script) will
           continue to work, but all new sets of codes will be added in the Locale::Codes namespace.

           The code2XXX, XXX2code, all_XXX_codes, and all_XXX_names functions now support retired codes.  All
           codesets may be specified by a constant or by their name now.  Previously, they were specified only by a
           constant.

           The alias_code function exists for backward compatibility.  It has been replaced by rename_country_code.
           The alias_code function will be removed some time after September, 2013.

           All work is now done in the central module (Locale::Codes).  Previously, some was still done in the
           wrapper modules (Locale::Codes::*).  Added Language Family codes (langfam) as defined in ISO 639-5.

       ·   Math::BigFloat has been upgraded from version 1.993 to 1.997.

           The "numify" method has been corrected to return a normalized Perl number (the result of "0 + $thing"),
           instead of a string [rt.cpan.org #66732].

       ·   Math::BigInt has been upgraded from version 1.994 to 1.998.

           It provides a new "bsgn" method that complements the "babs" method.

           It fixes the internal "objectify" function's handling of "foreign objects" so they are converted to the
           appropriate class (Math::BigInt or Math::BigFloat).

       ·   Math::BigRat has been upgraded from version 0.2602 to 0.2603.

           The "corelist" utility now understands the "-r" option for displaying Perl release dates and the "--diff"
           option to print the set of modlib changes between two perl distributions.

       ·   Module::Metadata has been upgraded from version 1.000004 to 1.000009.

           Adds "provides" method to generate a CPAN META provides data structure correctly; use of
           "package_versions_from_directory" is discouraged.

       ·   ODBM_File has been upgraded from version 1.10 to 1.12.

           The XS code is now compiled with "PERL_NO_GET_CONTEXT", which will aid performance under ithreads.

       ·   open has been upgraded from version 1.08 to 1.10.

           It no longer turns off layers on standard handles when invoked without the ":std" directive.  Similarly,
           when invoked with the ":std" directive, it now clears layers on STDERR before applying the new ones, and
           not just on STDIN and STDOUT [perl #92728].

       ·   overload has been upgraded from version 1.13 to 1.18.

           "overload::Overloaded" no longer calls "can" on the class, but uses another means to determine whether the
           object has overloading.  It was never correct for it to call "can", as overloading does not respect
           AUTOLOAD.  So classes that autoload methods and implement "can" no longer have to account for overloading
           [perl #40333].

           A warning is now produced for invalid arguments.  See "New Diagnostics".

       ·   PerlIO::scalar has been upgraded from version 0.11 to 0.14.

           (This is the module that implements "open $fh, '>', \$scalar".)

           It fixes a problem with "open my $fh, ">", \$scalar" not working if $scalar is a copy-on-write scalar.
           (5.14.2)

           It also fixes a hang that occurs with "readline" or "<$fh>" if a typeglob has been assigned to $scalar
           [perl #92258].

           It no longer assumes during "seek" that $scalar is a string internally.  If it didn't crash, it was close
           to doing so [perl #92706].  Also, the internal print routine no longer assumes that the position set by
           "seek" is valid, but extends the string to that position, filling the intervening bytes (between the old
           length and the seek position) with nulls [perl #78980].

           Printing to an in-memory handle now works if the $scalar holds a reference, stringifying the reference
           before modifying it.  References used to be treated as empty strings.

           Printing to an in-memory handle no longer crashes if the $scalar happens to hold a number internally, but
           no string buffer.

           Printing to an in-memory handle no longer creates scalars that confuse the regular expression engine [perl
           #108398].

       ·   Pod::Functions has been upgraded from version 1.04 to 1.05.

           Functions.pm is now generated at perl build time from annotations in perlfunc.pod.  This will ensure that

           This upgrade has numerous significant fixes.  Consult its changelog on the CPAN for more information.

       ·   POSIX has been upgraded from version 1.24 to 1.30.

           POSIX no longer uses AutoLoader.  Any code which was relying on this implementation detail was buggy, and
           may fail because of this change.  The module's Perl code has been considerably simplified, roughly halving
           the number of lines, with no change in functionality.  The XS code has been refactored to reduce the size
           of the shared object by about 12%, with no change in functionality.  More POSIX functions now have tests.

           "sigsuspend" and "pause" now run signal handlers before returning, as the whole point of these two
           functions is to wait until a signal has arrived, and then return after it has been triggered.  Delayed, or
           "safe", signals were preventing that from happening, possibly resulting in race conditions [perl #107216].

           "POSIX::sleep" is now a direct call into the underlying OS "sleep" function, instead of being a Perl
           wrapper on "CORE::sleep".  "POSIX::dup2" now returns the correct value on Win32 (i.e., the file
           descriptor).  "POSIX::SigSet" "sigsuspend" and "sigpending" and "POSIX::pause" now dispatch safe signals
           immediately before returning to their caller.

           "POSIX::Termios::setattr" now defaults the third argument to "TCSANOW", instead of 0. On most platforms
           "TCSANOW" is defined to be 0, but on some 0 is not a valid parameter, which caused a call with defaults to
           fail.

       ·   Socket has been upgraded from version 1.94 to 2.001.

           It has new functions and constants for handling IPv6 sockets:

               pack_ipv6_mreq
               unpack_ipv6_mreq
               IPV6_ADD_MEMBERSHIP
               IPV6_DROP_MEMBERSHIP
               IPV6_MTU
               IPV6_MTU_DISCOVER
               IPV6_MULTICAST_HOPS
               IPV6_MULTICAST_IF
               IPV6_MULTICAST_LOOP
               IPV6_UNICAST_HOPS
               IPV6_V6ONLY

       ·   Storable has been upgraded from version 2.27 to 2.34.

           It no longer turns copy-on-write scalars into read-only scalars when freezing and thawing.

       ·   Sys::Syslog has been upgraded from version 0.27 to 0.29.

           This upgrade closes many outstanding bugs.

       ·   Term::ANSIColor has been upgraded from version 3.00 to 3.01.

           Only interpret an initial array reference as a list of colors, not any initial reference, allowing the
           colored function to work properly on objects with stringification defined.

       ·   Term::ReadLine has been upgraded from version 1.07 to 1.09.


           Locales updated to CLDR 2.0: mk, mt, nb, nn, ro, ru, sk, sr, sv, uk, zh__pinyin, zh__stroke

           Newly supported locales: bn, fa, ml, mr, or, pa, sa, si, si__dictionary, sr_Latn, sv__reformed, ta, te,
           th, ur, wae.

           Tailored compatibility ideographs as well as unified ideographs for the locales: ja, ko, zh__big5han,
           zh__gb2312han, zh__pinyin, zh__stroke.

           Locale/*.pl files are now searched for in @INC.

       ·   Unicode::Normalize has been upgraded from version 1.10 to 1.14.

           Fixes for the removal of unicore/CompositionExclusions.txt from core.

       ·   Unicode::UCD has been upgraded from version 0.32 to 0.43.

           This adds four new functions:  "prop_aliases()" and "prop_value_aliases()", which are used to find all
           Unicode-approved synonyms for property names, or to convert from one name to another; "prop_invlist" which
           returns all code points matching a given Unicode binary property; and "prop_invmap" which returns the
           complete specification of a given Unicode property.

       ·   Win32API::File has been upgraded from version 0.1101 to 0.1200.

           Added SetStdHandle and GetStdHandle functions

   Removed Modules and Pragmata
       As promised in Perl 5.14.0's release notes, the following modules have been removed from the core
       distribution, and if needed should be installed from CPAN instead.

       ·   Devel::DProf has been removed from the Perl core.  Prior version was 20110228.00.

       ·   Shell has been removed from the Perl core.  Prior version was 0.72_01.

       ·   Several old perl4-style libraries which have been deprecated with 5.14 are now removed:

               abbrev.pl assert.pl bigfloat.pl bigint.pl bigrat.pl cacheout.pl
               complete.pl ctime.pl dotsh.pl exceptions.pl fastcwd.pl flush.pl
               getcwd.pl getopt.pl getopts.pl hostname.pl importenv.pl
               lib/find{,depth}.pl look.pl newgetopt.pl open2.pl open3.pl
               pwd.pl shellwords.pl stat.pl tainted.pl termcap.pl timelocal.pl

           They can be found on CPAN as Perl4::CoreLibs.

Documentation
   New Documentation
       perldtrace

       perldtrace describes Perl's DTrace support, listing the provided probes and gives examples of their use.

       perlexperiment

       This document is intended to provide a list of experimental features in Perl.  It is still a work in progress.


       ·   The HV API has long accepted negative lengths to show that the key is in UTF8.  This is now documented.

       ·   The "boolSV()" macro is now documented.

       perlfunc

       ·   "dbmopen" treats a 0 mode as a special case, that prevents a nonexistent file from being created.  This
           has been the case since Perl 5.000, but was never documented anywhere.  Now the perlfunc entry mentions it
           [perl #90064].

       ·   As an accident of history, "open $fh, '<:', ..." applies the default layers for the platform (":raw" on
           Unix, ":crlf" on Windows), ignoring whatever is declared by open.pm.  This seems such a useful feature it
           has been documented in perlfunc and open.

       ·   The entry for "split" has been rewritten.  It is now far clearer than before.

       perlguts

       ·   A new section, Autoloading with XSUBs, has been added, which explains the two APIs for accessing the name
           of the autoloaded sub.

       ·   Some function descriptions in perlguts were confusing, as it was not clear whether they referred to the
           function above or below the description.  This has been clarified [perl #91790].

       perlobj

       ·   This document has been rewritten from scratch, and its coverage of various OO concepts has been expanded.

       perlop

       ·   Documentation of the smartmatch operator has been reworked and moved from perlsyn to perlop where it
           belongs.

           It has also been corrected for the case of "undef" on the left-hand side.  The list of different smart
           match behaviors had an item in the wrong place.

       ·   Documentation of the ellipsis statement ("...") has been reworked and moved from perlop to perlsyn.

       ·   The explanation of bitwise operators has been expanded to explain how they work on Unicode strings
           (5.14.1).

       ·   More examples for "m//g" have been added (5.14.1).

       ·   The "<<\FOO" here-doc syntax has been documented (5.14.1).

       perlpragma

       ·   There is now a standard convention for naming keys in the "%^H", documented under Key naming.

       "Laundering and Detecting Tainted Data" in perlsec

       ·   The example function for checking for taintedness contained a subtle error.  $@ needs to be localized to
           prevent its changing this global's value outside the function.  The preferred method to check for this

       perlpodstyle

       ·   The tips on which formatting codes to use have been corrected and greatly expanded.

       ·   There are now a couple of example one-liners for previewing POD files after they have been edited.

       perlre

       ·   The "(*COMMIT)" directive is now listed in the right section (Verbs without an argument).

       perlrun

       ·   perlrun has undergone a significant clean-up.  Most notably, the -0x... form of the -0 flag has been
           clarified, and the final section on environment variables has been corrected and expanded (5.14.1).

       perlsub

       ·   The ($;) prototype syntax, which has existed for rather a long time, is now documented in perlsub.  It
           lets a unary function have the same precedence as a list operator.

       perltie

       ·   The required syntax for tying handles has been documented.

       perlvar

       ·   The documentation for $! has been corrected and clarified.  It used to state that $! could be "undef",
           which is not the case.  It was also unclear whether system calls set C's "errno" or Perl's $!  [perl
           #91614].

       ·   Documentation for $$ has been amended with additional cautions regarding changing the process ID.

       Other Changes

       ·   perlxs was extended with documentation on inline typemaps.

       ·   perlref has a new Circular References section explaining how circularities may not be freed and how to
           solve that with weak references.

       ·   Parts of perlapi were clarified, and Perl equivalents of some C functions have been added as an additional
           mode of exposition.

       ·   A few parts of perlre and perlrecharclass were clarified.

   Removed Documentation
       Old OO Documentation

       The old OO tutorials, perltoot, perltooc, and perlboot, have been removed.  The perlbot (bag of object tricks)
       document has been removed as well.

       Development Deltas

       The perldelta files for development releases are no longer packaged with perl.  These can still be found in
       the perl source code repository.

       ·   Cannot tie unreifiable array

           This error is part of a safety check that the "tie" operator does before tying a special array like @_.
           You should never see this message.

       ·   &CORE::%s cannot be called directly

           This occurs when a subroutine in the "CORE::" namespace is called with &foo syntax or through a reference.
           Some subroutines in this package cannot yet be called that way, but must be called as barewords.  See
           "Subroutines in the "CORE" namespace", above.

       ·   Source filters apply only to byte streams

           This new error occurs when you try to activate a source filter (usually by loading a source filter module)
           within a string passed to "eval" under the "unicode_eval" feature.

       New Warnings

       ·   defined(@array) is deprecated

           The long-deprecated "defined(@array)" now also warns for package variables.  Previously it issued a
           warning for lexical variables only.

       ·   length() used on %s

           This new warning occurs when "length" is used on an array or hash, instead of "scalar(@array)" or
           "scalar(keys %hash)".

       ·   lvalue attribute %s already-defined subroutine

           attributes.pm now emits this warning when the :lvalue attribute is applied to a Perl subroutine that has
           already been defined, as doing so can have unexpected side-effects.

       ·   overload arg '%s' is invalid

           This warning, in the "overload" category, is produced when the overload pragma is given an argument it
           doesn't recognize, presumably a mistyped operator.

       ·   $[ used in %s (did you mean $] ?)

           This new warning exists to catch the mistaken use of $[ in version checks.  $], not $[, contains the
           version number.

       ·   Useless assignment to a temporary

           Assigning to a temporary scalar returned from an lvalue subroutine now produces this warning [perl
           #31946].

       ·   Useless use of \E

           "\E" does nothing unless preceded by "\Q", "\L" or "\U".

   Removed Errors

       ·   The "Attempt to free non-existent shared string" has had the spelling of "non-existent" corrected to
           "nonexistent".  It was already listed with the correct spelling in perldiag.

       ·   The error messages for using "default" and "when" outside a topicalizer have been standardized to match
           the messages for "continue" and loop controls.  They now read 'Can't "default" outside a topicalizer' and
           'Can't "when" outside a topicalizer'.  They both used to be 'Can't use when() outside a topicalizer' [perl
           #91514].

       ·   The message, "Code point 0x%X is not Unicode, no properties match it; all inverse properties do" has been
           changed to "Code point 0x%X is not Unicode, all \p{} matches fail; all \P{} matches succeed".

       ·   Redefinition warnings for constant subroutines used to be mandatory, even occurring under "no warnings".
           Now they respect the warnings pragma.

       ·   The "glob failed" warning message is now suppressible via "no warnings" [perl #111656].

       ·   The Invalid version format error message now says "negative version number" within the parentheses, rather
           than "non-numeric data", for negative numbers.

       ·   The two warnings Possible attempt to put comments in qw() list and Possible attempt to separate words with
           commas are no longer mutually exclusive: the same "qw" construct may produce both.

       ·   The uninitialized warning for "y///r" when $_ is implicit and undefined now mentions the variable name,
           just like the non-/r variation of the operator.

       ·   The 'Use of "foo" without parentheses is ambiguous' warning has been extended to apply also to user-
           defined subroutines with a (;$) prototype, and not just to built-in functions.

       ·   Warnings that mention the names of lexical ("my") variables with Unicode characters in them now respect
           the presence or absence of the ":utf8" layer on the output handle, instead of outputting UTF8 regardless.
           Also, the correct names are included in the strings passed to $SIG{__WARN__} handlers, rather than the raw
           UTF8 bytes.

Utility Changes
       h2ph

       ·   h2ph used to generate code of the form

             unless(defined(&FOO)) {
               sub FOO () {42;}
             }

           But the subroutine is a compile-time declaration, and is hence unaffected by the condition.  It has now
           been corrected to emit a string "eval" around the subroutine [perl #99368].

       splain

       ·   splain no longer emits backtraces with the first line number repeated.

           This:

               Uncaught exception from user code:
                       Cannot fwiddle the fwuddle at -e line 1.
                at -e line 1

       ·   Some error messages consist of multiple lines that are listed as separate entries in perldiag.  splain has
           been taught to find the separate entries in these cases, instead of simply failing to find the message.

       zipdetails

       ·   This is a new utility, included as part of an IO::Compress::Base upgrade.

           zipdetails displays information about the internal record structure of the zip file.  It is not concerned
           with displaying any details of the compressed data stored in the zip file.

Configuration and Compilation
       ·   regexp.h has been modified for compatibility with GCC's -Werror option, as used by some projects that
           include perl's header files (5.14.1).

       ·   "USE_LOCALE{,_COLLATE,_CTYPE,_NUMERIC}" have been added the output of perl -V as they have affect the
           behavior of the interpreter binary (albeit in only a small area).

       ·   The code and tests for IPC::Open2 have been moved from ext/IPC-Open2 into ext/IPC-Open3, as
           "IPC::Open2::open2()" is implemented as a thin wrapper around "IPC::Open3::_open3()", and hence is very
           tightly coupled to it.

       ·   The magic types and magic vtables are now generated from data in a new script regen/mg_vtable.pl, instead
           of being maintained by hand.  As different EBCDIC variants can't agree on the code point for '~', the
           character to code point conversion is done at build time by generate_uudmap to a new generated header
           mg_data.h.  "PL_vtbl_bm" and "PL_vtbl_fm" are now defined by the pre-processor as "PL_vtbl_regexp",
           instead of being distinct C variables.  "PL_vtbl_sig" has been removed.

       ·   Building with "-DPERL_GLOBAL_STRUCT" works again.  This configuration is not generally used.

       ·   Perl configured with MAD now correctly frees "MADPROP" structures when OPs are freed.  "MADPROP"s are now
           allocated with "PerlMemShared_malloc()"

       ·   makedef.pl has been refactored.  This should have no noticeable affect on any of the platforms that use it
           as part of their build (AIX, VMS, Win32).

       ·   "useperlio" can no longer be disabled.

       ·   The file global.sym is no longer needed, and has been removed.  It contained a list of all exported
           functions, one of the files generated by regen/embed.pl from data in embed.fnc and regen/opcodes.  The
           code has been refactored so that the only user of global.sym, makedef.pl, now reads embed.fnc and
           regen/opcodes directly, removing the need to store the list of exported functions in an intermediate file.

           As global.sym was never installed, this change should not be visible outside the build process.

       ·   pod/buildtoc, used by the build process to build perltoc, has been refactored and simplified.  It now
           contains only code to build perltoc; the code to regenerate Makefiles has been moved to
           Porting/pod_rules.pl.  It's a bug if this change has any material effect on the build process.

       ·   pod/roffitall is now built by pod/buildtoc, instead of being shipped with the distribution.  Its list of
           manpages is now generated (and therefore current).  See also RT #103202 for an unresolved related issue.

       ·   The man page for "XS::Typemap" is no longer installed.  "XS::Typemap" is a test module which is not
           installed, hence installing its documentation makes no sense.


       HP-UX

       ·   HP-UX PA-RISC/64 now supports gcc-4.x

           A fix to correct the socketsize now makes the test suite pass on HP-UX PA-RISC for 64bitall builds.
           (5.14.2)

       VMS

       ·   Remove unnecessary includes, fix miscellaneous compiler warnings and close some unclosed comments on
           vms/vms.c.

       ·   Remove sockadapt layer from the VMS build.

       ·   Explicit support for VMS versions before v7.0 and DEC C versions before v6.0 has been removed.

       ·   Since Perl 5.10.1, the home-grown "stat" wrapper has been unable to distinguish between a directory name
           containing an underscore and an otherwise-identical filename containing a dot in the same position (e.g.,
           t/test_pl as a directory and t/test.pl as a file).  This problem has been corrected.

       ·   The build on VMS now permits names of the resulting symbols in C code for Perl longer than 31 characters.
           Symbols like "Perl__it_was_the_best_of_times_it_was_the_worst_of_times" can now be created freely without
           causing the VMS linker to seize up.

       GNU/Hurd

       ·   Numerous build and test failures on GNU/Hurd have been resolved with hints for building DBM modules,
           detection of the library search path, and enabling of large file support.

       OpenVOS

       ·   Perl is now built with dynamic linking on OpenVOS, the minimum supported version of which is now Release
           17.1.0.

       SunOS

       The CC workshop C++ compiler is now detected and used on systems that ship without cc.

Internal Changes
       ·   The compiled representation of formats is now stored via the "mg_ptr" of their "PERL_MAGIC_fm".
           Previously it was stored in the string buffer, beyond "SvLEN()", the regular end of the string.
           "SvCOMPILED()" and "SvCOMPILED_{on,off}()" now exist solely for compatibility for XS code.  The first is
           always 0, the other two now no-ops. (5.14.1)

       ·   Some global variables have been marked "const", members in the interpreter structure have been re-ordered,
           and the opcodes have been re-ordered.  The op "OP_AELEMFAST" has been split into "OP_AELEMFAST" and
           "OP_AELEMFAST_LEX".

       ·   When empting a hash of its elements (e.g., via undef(%h), or %h=()), HvARRAY field is no longer
           temporarily zeroed.  Any destructors called on the freed elements see the remaining elements.  Thus, %h=()
           becomes more like "delete $h{$_} for keys %h".

       ·   Boyer-Moore compiled scalars are now PVMGs, and the Boyer-Moore tables are now stored via the mg_ptr of
           their "PERL_MAGIC_bm".  Previously they were PVGVs, with the tables stored in the string buffer, beyond
           which already have the unknown magic type.

       ·   The experimental "fetch_cop_label" function has been renamed to "cop_fetch_label".

       ·   The "cop_store_label" function has been added to the API, but is experimental.

       ·   embedvar.h has been simplified, and one level of macro indirection for PL_* variables has been removed for
           the default (non-multiplicity) configuration.  PERLVAR*() macros now directly expand their arguments to
           tokens such as "PL_defgv", instead of expanding to "PL_Idefgv", with embedvar.h defining a macro to map
           "PL_Idefgv" to "PL_defgv".  XS code which has unwarranted chumminess with the implementation may need
           updating.

       ·   An API has been added to explicitly choose whether to export XSUB symbols.  More detail can be found in
           the comments for commit e64345f8.

       ·   The "is_gv_magical_sv" function has been eliminated and merged with "gv_fetchpvn_flags".  It used to be
           called to determine whether a GV should be autovivified in rvalue context.  Now it has been replaced with
           a new "GV_ADDMG" flag (not part of the API).

       ·   The returned code point from the function "utf8n_to_uvuni()" when the input is malformed UTF-8,
           malformations are allowed, and "utf8" warnings are off is now the Unicode REPLACEMENT CHARACTER whenever
           the malformation is such that no well-defined code point can be computed.  Previously the returned value
           was essentially garbage.  The only malformations that have well-defined values are a zero-length string (0
           is the return), and overlong UTF-8 sequences.

       ·   Padlists are now marked "AvREAL"; i.e., reference-counted.  They have always been reference-counted, but
           were not marked real, because pad.c did its own clean-up, instead of using the usual clean-up code in
           sv.c.  That caused problems in thread cloning, so now the "AvREAL" flag is on, but is turned off in pad.c
           right before the padlist is freed (after pad.c has done its custom freeing of the pads).

       ·   All C files that make up the Perl core have been converted to UTF-8.

       ·   These new functions have been added as part of the work on Unicode symbols:

               HvNAMELEN
               HvNAMEUTF8
               HvENAMELEN
               HvENAMEUTF8
               gv_init_pv
               gv_init_pvn
               gv_init_pvsv
               gv_fetchmeth_pv
               gv_fetchmeth_pvn
               gv_fetchmeth_sv
               gv_fetchmeth_pv_autoload
               gv_fetchmeth_pvn_autoload
               gv_fetchmeth_sv_autoload
               gv_fetchmethod_pv_flags
               gv_fetchmethod_pvn_flags
               gv_fetchmethod_sv_flags
               gv_autoload_pv
               gv_autoload_pvn
               gv_autoload_sv
               newGVgen_flags

           future release.

       ·   The following functions were added.  These are not part of the API:

               GvNAMEUTF8
               GvENAMELEN
               GvENAME_HEK
               CopSTASH_flags
               CopSTASH_flags_set
               PmopSTASH_flags
               PmopSTASH_flags_set
               sv_sethek
               HEKfARG

           There is also a "HEKf" macro corresponding to "SVf", for interpolating HEKs in formatted strings.

       ·   "sv_catpvn_flags" takes a couple of new internal-only flags, "SV_CATBYTES" and "SV_CATUTF8", which tell it
           whether the char array to be concatenated is UTF8.  This allows for more efficient concatenation than
           creating temporary SVs to pass to "sv_catsv".

       ·   For XS AUTOLOAD subs, $AUTOLOAD is set once more, as it was in 5.6.0.  This is in addition to setting
           "SvPVX(cv)", for compatibility with 5.8 to 5.14.  See "Autoloading with XSUBs" in perlguts.

       ·   Perl now checks whether the array (the linearized isa) returned by a MRO plugin begins with the name of
           the class itself, for which the array was created, instead of assuming that it does.  This prevents the
           first element from being skipped during method lookup.  It also means that "mro::get_linear_isa" may
           return an array with one more element than the MRO plugin provided [perl #94306].

       ·   "PL_curstash" is now reference-counted.

       ·   There are now feature bundle hints in "PL_hints" ($^H) that version declarations use, to avoid having to
           load feature.pm.  One setting of the hint bits indicates a "custom" feature bundle, which means that the
           entries in "%^H" still apply.  feature.pm uses that.

           The "HINT_FEATURE_MASK" macro is defined in perl.h along with other hints.  Other macros for setting and
           testing features and bundles are in the new feature.h.  "FEATURE_IS_ENABLED" (which has moved to
           feature.h) is no longer used throughout the codebase, but more specific macros, e.g.,
           "FEATURE_SAY_IS_ENABLED", that are defined in feature.h.

       ·   lib/feature.pm is now a generated file, created by the new regen/feature.pl script, which also generates
           feature.h.

       ·   Tied arrays are now always "AvREAL".  If @_ or "DB::args" is tied, it is reified first, to make sure this
           is always the case.

       ·   Two new functions "utf8_to_uvchr_buf()" and "utf8_to_uvuni_buf()" have been added.  These are the same as
           "utf8_to_uvchr" and "utf8_to_uvuni" (which are now deprecated), but take an extra parameter that is used
           to guard against reading beyond the end of the input string.  See "utf8_to_uvchr_buf" in perlapi and
           "utf8_to_uvuni_buf" in perlapi.

       ·   The regular expression engine now does TRIE case insensitive matches under Unicode. This may change the
           output of "use re 'debug';", and will speed up various things.

       ·   There is a new "wrap_op_checker()" function, which provides a thread-safe alternative to writing to

       ·   When hash elements are deleted in void context, the internal hash entry is now freed before the value is
           freed, to prevent destructors called by that latter freeing from seeing the hash in an inconsistent state.
           It was possible to cause double-frees if the destructor freed the hash itself [perl #100340].

       ·   A "keys" optimization in Perl 5.12.0 to make it faster on empty hashes caused "each" not to reset the
           iterator if called after the last element was deleted.

       ·   Freeing deeply nested hashes no longer crashes [perl #44225].

       ·   It is possible from XS code to create hashes with elements that have no values.  The hash element and
           slice operators used to crash when handling these in lvalue context.  They now produce a "Modification of
           non-creatable hash value attempted" error message.

       ·   If list assignment to a hash or array triggered destructors that freed the hash or array itself, a crash
           would ensue.  This is no longer the case [perl #107440].

       ·   It used to be possible to free the typeglob of a localized array or hash (e.g., "local @{"x"}; delete
           $::{x}"), resulting in a crash on scope exit.

       ·   Some core bugs affecting Hash::Util have been fixed: locking a hash element that is a glob copy no longer
           causes the next assignment to it to corrupt the glob (5.14.2), and unlocking a hash element that holds a
           copy-on-write scalar no longer causes modifications to that scalar to modify other scalars that were
           sharing the same string buffer.

   C API fixes
       ·   The "newHVhv" XS function now works on tied hashes, instead of crashing or returning an empty hash.

       ·   The "SvIsCOW" C macro now returns false for read-only copies of typeglobs, such as those created by:

             $hash{elem} = *foo;
             Hash::Util::lock_value %hash, 'elem';

           It used to return true.

       ·   The "SvPVutf8" C function no longer tries to modify its argument, resulting in errors [perl #108994].

       ·   "SvPVutf8" now works properly with magical variables.

       ·   "SvPVbyte" now works properly non-PVs.

       ·   When presented with malformed UTF-8 input, the XS-callable functions "is_utf8_string()",
           "is_utf8_string_loc()", and "is_utf8_string_loclen()" could read beyond the end of the input string by up
           to 12 bytes.  This no longer happens.  [perl #32080].  However, currently, "is_utf8_char()" still has this
           defect, see "is_utf8_char()" above.

       ·   The C-level "pregcomp" function could become confused about whether the pattern was in UTF8 if the pattern
           was an overloaded, tied, or otherwise magical scalar [perl #101940].

   Compile-time hints
       ·   Tying "%^H" no longer causes perl to crash or ignore the contents of "%^H" when entering a compilation
           scope [perl #106282].

       ·   "eval $string" and "require" used not to localize "%^H" during compilation if it was empty at the time the
       (they were used mostly internally).  Perl 5.10.0 extended them, such that assigning "__PACKAGE__" or a hash
       key to a scalar would make it copy-on-write.  Several parts of Perl were not updated to account for them, but
       have now been fixed.

       ·   "utf8::decode" had a nasty bug that would modify copy-on-write scalars' string buffers in place (i.e.,
           skipping the copy).  This could result in hashes having two elements with the same key [perl #91834].
           (5.14.2)

       ·   Lvalue subroutines were not allowing COW scalars to be returned.  This was fixed for lvalue scalar context
           in Perl 5.12.3 and 5.14.0, but list context was not fixed until this release.

       ·   Elements of restricted hashes (see the fields pragma) containing copy-on-write values couldn't be deleted,
           nor could such hashes be cleared ("%hash = ()"). (5.14.2)

       ·   Localizing a tied variable used to make it read-only if it contained a copy-on-write string. (5.14.2)

       ·   Assigning a copy-on-write string to a stash element no longer causes a double free.  Regardless of this
           change, the results of such assignments are still undefined.

       ·   Assigning a copy-on-write string to a tied variable no longer stops that variable from being tied if it
           happens to be a PVMG or PVLV internally.

       ·   Doing a substitution on a tied variable returning a copy-on-write scalar used to cause an assertion
           failure or an "Attempt to free nonexistent shared string" warning.

       ·   This one is a regression from 5.12: In 5.14.0, the bitwise assignment operators "|=", "^=" and "&="
           started leaving the left-hand side undefined if it happened to be a copy-on-write string [perl #108480].

       ·   Storable, Devel::Peek and PerlIO::scalar had similar problems.  See "Updated Modules and Pragmata", above.

   The debugger
       ·   dumpvar.pl, and therefore the "x" command in the debugger, have been fixed to handle objects blessed into
           classes whose names contain "=".  The contents of such objects used not to be dumped [perl #101814].

       ·   The "R" command for restarting a debugger session has been fixed to work on Windows, or any other system
           lacking a "POSIX::_SC_OPEN_MAX" constant [perl #87740].

       ·   The "#line 42 foo" directive used not to update the arrays of lines used by the debugger if it occurred in
           a string eval.  This was partially fixed in 5.14, but it worked only for a single "#line 42 foo" in each
           eval.  Now it works for multiple.

       ·   When subroutine calls are intercepted by the debugger, the name of the subroutine or a reference to it is
           stored in $DB::sub, for the debugger to access.  Sometimes (such as "$foo = *bar; undef *bar; &$foo")
           $DB::sub would be set to a name that could not be used to find the subroutine, and so the debugger's
           attempt to call it would fail.  Now the check to see whether a reference is needed is more robust, so
           those problems should not happen anymore [rt.cpan.org #69862].

       ·   Every subroutine has a filename associated with it that the debugger uses.  The one associated with
           constant subroutines used to be misallocated when cloned under threads.  Consequently, debugging threaded
           applications could result in memory corruption [perl #96126].

   Dereferencing operators
       ·   "defined(${"..."})", "defined(*{"..."})", etc., used to return true for most, but not all built-in
           variables, if they had not been used yet.  This bug affected "${^GLOBAL_PHASE}" and "${^UTF8CACHE}", among

   Filehandle, last-accessed
       Perl has an internal variable that stores the last filehandle to be accessed.  It is used by $. and by "tell"
       and "eof" without arguments.

       ·   It used to be possible to set this internal variable to a glob copy and then modify that glob copy to be
           something other than a glob, and still have the last-accessed filehandle associated with the variable
           after assigning a glob to it again:

               my $foo = *STDOUT;  # $foo is a glob copy
               <$foo>;             # $foo is now the last-accessed handle
               $foo = 3;           # no longer a glob
               $foo = *STDERR;     # still the last-accessed handle

           Now the "$foo = 3" assignment unsets that internal variable, so there is no last-accessed filehandle, just
           as if "<$foo>" had never happened.

           This also prevents some unrelated handle from becoming the last-accessed handle if $foo falls out of scope
           and the same internal SV gets used for another handle [perl #97988].

       ·   A regression in 5.14 caused these statements not to set that internal variable:

               my $fh = *STDOUT;
               tell $fh;
               eof  $fh;
               seek $fh, 0,0;
               tell     *$fh;
               eof      *$fh;
               seek     *$fh, 0,0;
               readline *$fh;

           This is now fixed, but "tell *{ *$fh }" still has the problem, and it is not clear how to fix it [perl
           #106536].

   Filetests and "stat"
       The term "filetests" refers to the operators that consist of a hyphen followed by a single letter: "-r", "-x",
       "-M", etc.  The term "stacked" when applied to filetests means followed by another filetest operator sharing
       the same operand, as in "-r -x -w $fooo".

       ·   "stat" produces more consistent warnings.  It no longer warns for "_" [perl #71002] and no longer skips
           the warning at times for other unopened handles.  It no longer warns about an unopened handle when the
           operating system's "fstat" function fails.

       ·   "stat" would sometimes return negative numbers for large inode numbers, because it was using the wrong
           internal C type. [perl #84590]

       ·   "lstat" is documented to fall back to "stat" (with a warning) when given a filehandle.  When passed an IO
           reference, it was actually doing the equivalent of "stat _" and ignoring the handle.

       ·   "-T _" with no preceding "stat" used to produce a confusing "uninitialized" warning, even though there is
           no visible uninitialized value to speak of.

       ·   "-T", "-B", "-l" and "-t" now work when stacked with other filetest operators [perl #77388].

       ·   In 5.14.0, filetest ops ("-r", "-x", etc.) started calling FETCH on a tied argument belonging to the
       ·   Perl keeps several internal variables to keep track of the last stat buffer, from which file(handle) it
           originated, what type it was, and whether the last stat succeeded.

           There were various cases where these could get out of synch, resulting in inconsistent or erratic behavior
           in edge cases (every mention of "-T" applies to "-B" as well):

           ·   "-T HANDLE", even though it does a "stat", was not resetting the last stat type, so an "lstat _"
               following it would merrily return the wrong results.  Also, it was not setting the success status.

           ·   Freeing the handle last used by "stat" or a filetest could result in "-T _" using an unrelated handle.

           ·   "stat" with an IO reference would not reset the stat type or record the filehandle for "-T _" to use.

           ·   Fatal warnings could cause the stat buffer not to be reset for a filetest operator on an unopened
               filehandle or "-l" on any handle.  Fatal warnings also stopped "-T" from setting $!.

           ·   When the last stat was on an unreadable file, "-T _" is supposed to return "undef", leaving the last
               stat buffer unchanged.  But it was setting the stat type, causing "lstat _" to stop working.

           ·   "-T FILENAME" was not resetting the internal stat buffers for unreadable files.

           These have all been fixed.

   Formats
       ·   Several edge cases have been fixed with formats and "formline"; in particular, where the format itself is
           potentially variable (such as with ties and overloading), and where the format and data differ in their
           encoding.  In both these cases, it used to possible for the output to be corrupted [perl #91032].

       ·   "formline" no longer converts its argument into a string in-place.  So passing a reference to "formline"
           no longer destroys the reference [perl #79532].

       ·   Assignment to $^A (the format output accumulator) now recalculates the number of lines output.

   "given" and "when"
       ·   "given" was not scoping its implicit $_ properly, resulting in memory leaks or "Variable is not available"
           warnings [perl #94682].

       ·   "given" was not calling set-magic on the implicit lexical $_ that it uses.  This meant, for example, that
           "pos" would be remembered from one execution of the same "given" block to the next, even if the input were
           a different variable [perl #84526].

       ·   "when" blocks are now capable of returning variables declared inside the enclosing "given" block [perl
           #93548].

   The "glob" operator
       ·   On OSes other than VMS, Perl's "glob" operator (and the "<...>" form) use File::Glob underneath.
           File::Glob splits the pattern into words, before feeding each word to its "bsd_glob" function.

           There were several inconsistencies in the way the split was done.  Now quotation marks (' and ") are
           always treated as shell-style word delimiters (that allow whitespace as part of a word) and backslashes
           are always preserved, unless they exist to escape quotation marks.  Before, those would only sometimes be
           the case, depending on whether the pattern contained whitespace.  Also, escaped whitespace at the end of
           the pattern is no longer stripped [perl #40470].

           the last statement and the arguments to return.  Since lvalue subroutines are not always called in lvalue
           context, this restriction has been lifted.

       ·   Lvalue subroutines are less restrictive about what values can be returned.  It used to croak on values
           returned by "shift" and "delete" and from other subroutines, but no longer does so [perl #71172].

       ·   Empty lvalue subroutines ("sub :lvalue {}") used to return @_ in list context.  All subroutines used to do
           this, but regular subs were fixed in Perl 5.8.2.  Now lvalue subroutines have been likewise fixed.

       ·   Autovivification now works on values returned from lvalue subroutines [perl #7946], as does returning
           "keys" in lvalue context.

       ·   Lvalue subroutines used to copy their return values in rvalue context.  Not only was this a waste of CPU
           cycles, but it also caused bugs.  A "($)" prototype would cause an lvalue sub to copy its return value
           [perl #51408], and "while(lvalue_sub() =~ m/.../g) { ... }" would loop endlessly [perl #78680].

       ·   When called in potential lvalue context (e.g., subroutine arguments or a list passed to "for"), lvalue
           subroutines used to copy any read-only value that was returned.  E.g., " sub :lvalue { $] } " would not
           return $], but a copy of it.

       ·   When called in potential lvalue context, an lvalue subroutine returning arrays or hashes used to bind the
           arrays or hashes to scalar variables, resulting in bugs.  This was fixed in 5.14.0 if an array were the
           first thing returned from the subroutine (but not for "$scalar, @array" or hashes being returned).  Now a
           more general fix has been applied [perl #23790].

       ·   Method calls whose arguments were all surrounded with "my()" or "our()" (as in
           "$object->method(my($a,$b))") used to force lvalue context on the subroutine.  This would prevent lvalue
           methods from returning certain values.

       ·   Lvalue sub calls that are not determined to be such at compile time (&$name or &{"name"}) are no longer
           exempt from strict refs if they occur in the last statement of an lvalue subroutine [perl #102486].

       ·   Sub calls whose subs are not visible at compile time, if they occurred in the last statement of an lvalue
           subroutine, would reject non-lvalue subroutines and die with "Can't modify non-lvalue subroutine call"
           [perl #102486].

           Non-lvalue sub calls whose subs are visible at compile time exhibited the opposite bug.  If the call
           occurred in the last statement of an lvalue subroutine, there would be no error when the lvalue sub was
           called in lvalue context.  Perl would blindly assign to the temporary value returned by the non-lvalue
           subroutine.

       ·   "AUTOLOAD" routines used to take precedence over the actual sub being called (i.e., when autoloading
           wasn't needed), for sub calls in lvalue or potential lvalue context, if the subroutine was not visible at
           compile time.

       ·   Applying the ":lvalue" attribute to an XSUB or to an aliased subroutine stub with "sub foo :lvalue;"
           syntax stopped working in Perl 5.12.  This has been fixed.

       ·   Applying the :lvalue attribute to subroutine that is already defined does not work properly, as the
           attribute changes the way the sub is compiled.  Hence, Perl 5.12 began warning when an attempt is made to
           apply the attribute to an already defined sub.  In such cases, the attribute is discarded.

           But the change in 5.12 missed the case where custom attributes are also present: that case still silently
           and ineffectively applied the attribute.  That omission has now been corrected.  "sub foo :lvalue

       ·   Undefining %overload:: no longer causes a crash.

   Prototypes of built-in keywords
       ·   The "prototype" function no longer dies for the "__FILE__", "__LINE__" and "__PACKAGE__" directives.  It
           now returns an empty-string prototype for them, because they are syntactically indistinguishable from
           nullary functions like "time".

       ·   "prototype" now returns "undef" for all overridable infix operators, such as "eq", which are not callable
           in any way resembling functions.  It used to return incorrect prototypes for some and die for others [perl
           #94984].

       ·   The prototypes of several built-in functions--"getprotobynumber", "lock", "not" and "select"--have been
           corrected, or at least are now closer to reality than before.

   Regular expressions
       ·   "/[[:ascii:]]/" and "/[[:blank:]]/" now use locale rules under "use locale" when the platform supports
           that.  Previously, they used the platform's native character set.

       ·   "m/[[:ascii:]]/i" and "/\p{ASCII}/i" now match identically (when not under a differing locale).  This
           fixes a regression introduced in 5.14 in which the first expression could match characters outside of
           ASCII, such as the KELVIN SIGN.

       ·   "/.*/g" would sometimes refuse to match at the end of a string that ends with "\n".  This has been fixed
           [perl #109206].

       ·   Starting with 5.12.0, Perl used to get its internal bookkeeping muddled up after assigning "${ qr// }" to
           a hash element and locking it with Hash::Util.  This could result in double frees, crashes, or erratic
           behavior.

       ·   The new (in 5.14.0) regular expression modifier "/a" when repeated like "/aa" forbids the characters
           outside the ASCII range that match characters inside that range from matching under "/i".  This did not
           work under some circumstances, all involving alternation, such as:

            "\N{KELVIN SIGN}" =~ /k|foo/iaa;

           succeeded inappropriately.  This is now fixed.

       ·   5.14.0 introduced some memory leaks in regular expression character classes such as "[\w\s]", which have
           now been fixed. (5.14.1)

       ·   An edge case in regular expression matching could potentially loop.  This happened only under "/i" in
           bracketed character classes that have characters with multi-character folds, and the target string to
           match against includes the first portion of the fold, followed by another character that has a multi-
           character fold that begins with the remaining portion of the fold, plus some more.

            "s\N{U+DF}" =~ /[\x{DF}foo]/i

           is one such case.  "\xDF" folds to "ss". (5.14.1)

       ·   A few characters in regular expression pattern matches did not match correctly in some circumstances, all
           involving "/i".  The affected characters are: COMBINING GREEK YPOGEGRAMMENI, GREEK CAPITAL LETTER IOTA,
           GREEK CAPITAL LETTER UPSILON, GREEK PROSGEGRAMMENI, GREEK SMALL LETTER IOTA WITH DIALYTIKA AND OXIA, GREEK
           SMALL LETTER IOTA WITH DIALYTIKA AND TONOS, GREEK SMALL LETTER UPSILON WITH DIALYTIKA AND OXIA, GREEK
           AND TONOS, and GREEK SMALL LETTER UPSILON WITH DIALYTIKA AND TONOS, along with the sequences that they
           fold to (including "ss" for LATIN SMALL LETTER SHARP S), did not properly match under "/i".  5.14.0 fixed
           some of these cases, but introduced others, including a panic when one of the characters or sequences was
           used in the "(?(DEFINE)" regular expression predicate.  The known bugs that were introduced in 5.14 have
           now been fixed; as well as some other edge cases that have never worked until now.  These all involve
           using the characters and sequences outside bracketed character classes under "/i".  This closes [perl
           #98546].

           There remain known problems when using certain characters with multi-character folds inside bracketed
           character classes, including such constructs as "qr/[\N{LATIN SMALL LETTER SHARP}a-z]/i".  These remaining
           bugs are addressed in [perl #89774].

       ·   RT #78266: The regex engine has been leaking memory when accessing named captures that weren't matched as
           part of a regex ever since 5.10 when they were introduced; e.g., this would consume over a hundred MB of
           memory:

               for (1..10_000_000) {
                   if ("foo" =~ /(foo|(?<capture>bar))?/) {
                       my $capture = $+{capture}
                   }
               }
               system "ps -o rss $$"'

       ·   In 5.14, "/[[:lower:]]/i" and "/[[:upper:]]/i" no longer matched the opposite case.  This has been fixed
           [perl #101970].

       ·   A regular expression match with an overloaded object on the right-hand side would sometimes stringify the
           object too many times.

       ·   A regression has been fixed that was introduced in 5.14, in "/i" regular expression matching, in which a
           match improperly fails if the pattern is in UTF-8, the target string is not, and a Latin-1 character
           precedes a character in the string that should match the pattern.  [perl #101710]

       ·   In case-insensitive regular expression pattern matching, no longer on UTF-8 encoded strings does the scan
           for the start of match look only at the first possible position.  This caused matches such as ""f\x{FB00}"
           =~ /ff/i" to fail.

       ·   The regexp optimizer no longer crashes on debugging builds when merging fixed-string nodes with
           inconvenient contents.

       ·   A panic involving the combination of the regular expression modifiers "/aa" and the "\b" escape sequence
           introduced in 5.14.0 has been fixed [perl #95964]. (5.14.2)

       ·   The combination of the regular expression modifiers "/aa" and the "\b" and "\B" escape sequences did not
           work properly on UTF-8 encoded strings.  All non-ASCII characters under "/aa" should be treated as non-
           word characters, but what was happening was that Unicode rules were used to determine
           wordness/non-wordness for non-ASCII characters.  This is now fixed [perl #95968].

       ·   "(?foo: ...)" no longer loses passed in character set.

       ·   The trie optimization used to have problems with alternations containing an empty "(?:)", causing ""x" =~
           /\A(?>(?:(?:)A|B|C?x))\z/" not to match, whereas it should [perl #111842].

       ·   Use of lexical ("my") variables in code blocks embedded in regular expressions will no longer result in
       ·   Mentioning a variable named "&" other than $& (i.e., "@&" or "%&") no longer stops $& from working.  The
           same applies to variables named "'" and "`" [perl #24237].

       ·   Creating a "UNIVERSAL::AUTOLOAD" sub no longer stops "%+", "%-" and "%!" from working some of the time
           [perl #105024].

   Smartmatching
       ·   "~~" now correctly handles the precedence of Any~~Object, and is not tricked by an overloaded object on
           the left-hand side.

       ·   In Perl 5.14.0, "$tainted ~~ @array" stopped working properly.  Sometimes it would erroneously fail (when
           $tainted contained a string that occurs in the array after the first element) or erroneously succeed (when
           "undef" occurred after the first element) [perl #93590].

   The "sort" operator
       ·   "sort" was not treating "sub {}" and "sub {()}" as equivalent when such a sub was provided as the
           comparison routine.  It used to croak on "sub {()}".

       ·   "sort" now works once more with custom sort routines that are XSUBs.  It stopped working in 5.10.0.

       ·   "sort" with a constant for a custom sort routine, although it produces unsorted results, no longer
           crashes.  It started crashing in 5.10.0.

       ·   Warnings emitted by "sort" when a custom comparison routine returns a non-numeric value now contain "in
           sort" and show the line number of the "sort" operator, rather than the last line of the comparison
           routine.  The warnings also now occur only if warnings are enabled in the scope where "sort" occurs.
           Previously the warnings would occur if enabled in the comparison routine's scope.

       ·   "sort { $a <=> $b }", which is optimized internally, now produces "uninitialized" warnings for NaNs (not-
           a-number values), since "<=>" returns "undef" for those.  This brings it in line with
           "sort { 1; $a <=> $b }" and other more complex cases, which are not optimized [perl #94390].

   The "substr" operator
       ·   Tied (and otherwise magical) variables are no longer exempt from the "Attempt to use reference as lvalue
           in substr" warning.

       ·   That warning now occurs when the returned lvalue is assigned to, not when "substr" itself is called.  This
           makes a difference only if the return value of "substr" is referenced and later assigned to.

       ·   Passing a substring of a read-only value or a typeglob to a function (potential lvalue context) no longer
           causes an immediate "Can't coerce" or "Modification of a read-only value" error.  That error occurs only
           if the passed value is assigned to.

           The same thing happens with the "substr outside of string" error.  If the lvalue is only read from, not
           written to, it is now just a warning, as with rvalue "substr".

       ·   "substr" assignments no longer call FETCH twice if the first argument is a tied variable, just once.

   Support for embedded nulls
       Some parts of Perl did not work correctly with nulls ("chr 0") embedded in strings.  That meant that, for
       instance, "$m = "a\0b"; foo->$m" would call the "a" method, instead of the actual method name contained in $m.
       These parts of perl have been fixed to support nulls:

       ·   Method names

   Threading bugs
       ·   Typeglobs returned from threads are no longer cloned if the parent thread already has a glob with the same
           name.  This means that returned subroutines will now assign to the right package variables [perl #107366].

       ·   Some cases of threads crashing due to memory allocation during cloning have been fixed [perl #90006].

       ·   Thread joining would sometimes emit "Attempt to free unreferenced scalar" warnings if "caller" had been
           used from the "DB" package before thread creation [perl #98092].

       ·   Locking a subroutine (via "lock &sub") is no longer a compile-time error for regular subs.  For lvalue
           subroutines, it no longer tries to return the sub as a scalar, resulting in strange side effects like "ref
           \$_" returning "CODE" in some instances.

           "lock &sub" is now a run-time error if threads::shared is loaded (a no-op otherwise), but that may be
           rectified in a future version.

   Tied variables
       ·   Various cases in which FETCH was being ignored or called too many times have been fixed:

           ·   "PerlIO::get_layers" [perl #97956]

           ·   "$tied =~ y/a/b/", "chop $tied" and "chomp $tied" when $tied holds a reference.

           ·   When calling "local $_" [perl #105912]

           ·   Four-argument "select"

           ·   A tied buffer passed to "sysread"

           ·   "$tied .= <>"

           ·   Three-argument "open", the third being a tied file handle (as in "open $fh, ">&", $tied")

           ·   "sort" with a reference to a tied glob for the comparison routine.

           ·   ".." and "..." in list context [perl #53554].

           ·   "${$tied}", "@{$tied}", "%{$tied}" and "*{$tied}" where the tied variable returns a string ("&{}" was
               unaffected)

           ·   "defined ${ $tied_variable }"

           ·   Various functions that take a filehandle argument in rvalue context ("close", "readline", etc.) [perl
               #97482]

           ·   Some cases of dereferencing a complex expression, such as "${ (), $tied } = 1", used to call "FETCH"
               multiple times, but now call it once.

           ·   "$tied->method" where $tied returns a package name--even resulting in a failure to call the method,
               due to memory corruption

           ·   Assignments like "*$tied = \&{"..."}" and "*glob = $tied"

           returned the same reference.  This can make it easier to implement tied objects [perl #35865, #43011].

       ·   Four-argument "select" no longer produces its "Non-string passed as bitmask" warning on tied or tainted
           variables that are strings.

       ·   Localizing a tied scalar that returns a typeglob no longer stops it from being tied till the end of the
           scope.

       ·   Attempting to "goto" out of a tied handle method used to cause memory corruption or crashes.  Now it
           produces an error message instead [perl #8611].

       ·   A bug has been fixed that occurs when a tied variable is used as a subroutine reference:  if the last
           thing assigned to or returned from the variable was a reference or typeglob, the "\&$tied" could either
           crash or return the wrong subroutine.  The reference case is a regression introduced in Perl 5.10.0.  For
           typeglobs, it has probably never worked till now.

   Version objects and vstrings
       ·   The bitwise complement operator (and possibly other operators, too) when passed a vstring would leave
           vstring magic attached to the return value, even though the string had changed.  This meant that
           "version->new(~v1.2.3)" would create a version looking like "v1.2.3" even though the string passed to
           "version->new" was actually "\376\375\374".  This also caused B::Deparse to deparse "~v1.2.3" incorrectly,
           without the "~" [perl #29070].

       ·   Assigning a vstring to a magic (e.g., tied, $!) variable and then assigning something else used to blow
           away all magic.  This meant that tied variables would come undone, $! would stop getting updated on failed
           system calls, $| would stop setting autoflush, and other mischief would take place.  This has been fixed.

       ·   "version->new("version")" and "printf "%vd", "version"" no longer crash [perl #102586].

       ·   Version comparisons, such as those that happen implicitly with "use v5.43", no longer cause locale
           settings to change [perl #105784].

       ·   Version objects no longer cause memory leaks in boolean context [perl #109762].

   Warnings, redefinition
       ·   Subroutines from the "autouse" namespace are once more exempt from redefinition warnings.  This used to
           work in 5.005, but was broken in 5.6 for most subroutines.  For subs created via XS that redefine
           subroutines from the "autouse" package, this stopped working in 5.10.

       ·   New XSUBs now produce redefinition warnings if they overwrite existing subs, as they did in 5.8.x.  (The
           "autouse" logic was reversed in 5.10-14.  Only subroutines from the "autouse" namespace would warn when
           clobbered.)

       ·   "newCONSTSUB" used to use compile-time warning hints, instead of run-time hints.  The following code
           should never produce a redefinition warning, but it used to, if "newCONSTSUB" redefined an existing
           subroutine:

               use warnings;
               BEGIN {
                   no warnings;
                   some_XS_function_that_calls_new_CONSTSUB();
               }

       ·   Redefinition warnings for constant subroutines are on by default (what are known as severe warnings in

   Warnings, "Uninitialized"
       ·   Various functions that take a filehandle argument in rvalue context ("close", "readline", etc.) used to
           warn twice for an undefined handle [perl #97482].

       ·   "dbmopen" now only warns once, rather than three times, if the mode argument is "undef" [perl #90064].

       ·   The "+=" operator does not usually warn when the left-hand side is "undef", but it was doing so for tied
           variables.  This has been fixed [perl #44895].

       ·   A bug fix in Perl 5.14 introduced a new bug, causing "uninitialized" warnings to report the wrong variable
           if the operator in question had two operands and one was "%{...}" or "@{...}".  This has been fixed [perl
           #103766].

       ·   ".." and "..." in list context now mention the name of the variable in "uninitialized" warnings for string
           (as opposed to numeric) ranges.

   Weak references
       ·   Weakening the first argument to an automatically-invoked "DESTROY" method could result in erroneous
           "DESTROY created new reference" errors or crashes.  Now it is an error to weaken a read-only reference.

       ·   Weak references to lexical hashes going out of scope were not going stale (becoming undefined), but
           continued to point to the hash.

       ·   Weak references to lexical variables going out of scope are now broken before any magical methods (e.g.,
           DESTROY on a tie object) are called.  This prevents such methods from modifying the variable that will be
           seen the next time the scope is entered.

       ·   Creating a weak reference to an @ISA array or accessing the array index ($#ISA) could result in confused
           internal bookkeeping for elements later added to the @ISA array.  For instance, creating a weak reference
           to the element itself could push that weak reference on to @ISA; and elements added after use of $#ISA
           would be ignored by method lookup [perl #85670].

   Other notable fixes
       ·   "quotemeta" now quotes consistently the same non-ASCII characters under "use feature 'unicode_strings'",
           regardless of whether the string is encoded in UTF-8 or not, hence fixing the last vestiges (we hope) of
           the notorious "The "Unicode Bug"" in perlunicode.  [perl #77654].

           Which of these code points is quoted has changed, based on Unicode's recommendations.  See "quotemeta" in
           perlfunc for details.

       ·   "study" is now a no-op, presumably fixing all outstanding bugs related to study causing regex matches to
           behave incorrectly!

       ·   When one writes "open foo || die", which used to work in Perl 4, a "Precedence problem" warning is
           produced.  This warning used erroneously to apply to fully-qualified bareword handle names not followed by
           "||".  This has been corrected.

       ·   After package aliasing ("*foo:: = *bar::"), "select" with 0 or 1 argument would sometimes return a name
           that could not be used to refer to the filehandle, or sometimes it would return "undef" even when a
           filehandle was selected.  Now it returns a typeglob reference in such cases.

       ·   "PerlIO::get_layers" no longer ignores some arguments that it thinks are numeric, while treating others as
           filehandle names.  It is now consistent for flat scalars (i.e., not references).


       ·   The %n formatting code for "printf" and "sprintf", which causes the number of characters to be assigned to
           the next argument, now actually assigns the number of characters, instead of the number of bytes.

           It also works now with special lvalue functions like "substr" and with nonexistent hash and array elements
           [perl #3471, #103492].

       ·   Perl skips copying values returned from a subroutine, for the sake of speed, if doing so would make no
           observable difference.  Because of faulty logic, this would happen with the result of "delete", "shift" or
           "splice", even if the result was referenced elsewhere.  It also did so with tied variables about to be
           freed [perl #91844, #95548].

       ·   "utf8::decode" now refuses to modify read-only scalars [perl #91850].

       ·   Freeing $_ inside a "grep" or "map" block, a code block embedded in a regular expression, or an @INC
           filter (a subroutine returned by a subroutine in @INC) used to result in double frees or crashes [perl
           #91880, #92254, #92256].

       ·   "eval" returns "undef" in scalar context or an empty list in list context when there is a run-time error.
           When "eval" was passed a string in list context and a syntax error occurred, it used to return a list
           containing a single undefined element.  Now it returns an empty list in list context for all errors [perl
           #80630].

       ·   "goto &func" no longer crashes, but produces an error message, when the unwinding of the current
           subroutine's scope fires a destructor that undefines the subroutine being "goneto" [perl #99850].

       ·   Perl now holds an extra reference count on the package that code is currently compiling in.  This means
           that the following code no longer crashes [perl #101486]:

               package Foo;
               BEGIN {*Foo:: = *Bar::}
               sub foo;

       ·   The "x" repetition operator no longer crashes on 64-bit builds with large repeat counts [perl #94560].

       ·   Calling "require" on an implicit $_ when *CORE::GLOBAL::require has been overridden does not segfault
           anymore, and $_ is now passed to the overriding subroutine [perl #78260].

       ·   "use" and "require" are no longer affected by the I/O layers active in the caller's scope (enabled by
           open.pm) [perl #96008].

       ·   "our $::e; $e" (which is invalid) no longer produces the "Compilation error at lib/utf8_heavy.pl..." error
           message, which it started emitting in 5.10.0 [perl #99984].

       ·   On 64-bit systems, "read()" now understands large string offsets beyond the 32-bit range.

       ·   Errors that occur when processing subroutine attributes no longer cause the subroutine's op tree to leak.

       ·   Passing the same constant subroutine to both "index" and "formline" no longer causes one or the other to
           fail [perl #89218]. (5.14.1)

       ·   List assignment to lexical variables declared with attributes in the same statement ("my ($x,@y) : blimp =
           (72,94)") stopped working in Perl 5.8.0.  It has now been fixed.


       ·   "each(ARRAY)" is now wrapped in "defined(...)", like "each(HASH)", inside a "while" condition [perl
           #90888].

       ·   A problem with context propagation when a "do" block is an argument to "return" has been fixed.  It used
           to cause "undef" to be returned in certain cases of a "return" inside an "if" block which itself is
           followed by another "return".

       ·   Calling "index" with a tainted constant no longer causes constants in subsequently compiled code to become
           tainted [perl #64804].

       ·   Infinite loops like "1 while 1" used to stop "strict 'subs'" mode from working for the rest of the block.

       ·   For list assignments like "($a,$b) = ($b,$a)", Perl has to make a copy of the items on the right-hand side
           before assignment them to the left.  For efficiency's sake, it assigns the values on the right straight to
           the items on the left if no one variable is mentioned on both sides, as in "($a,$b) = ($c,$d)".  The logic
           for determining when it can cheat was faulty, in that "&&" and "||" on the right-hand side could fool it.
           So "($a,$b) = $some_true_value && ($b,$a)" would end up assigning the value of $b to both scalars.

       ·   Perl no longer tries to apply lvalue context to the string in "("string", $variable) ||= 1" (which used to
           be an error).  Since the left-hand side of "||=" is evaluated in scalar context, that's a scalar comma
           operator, which gives all but the last item void context.  There is no such thing as void lvalue context,
           so it was a mistake for Perl to try to force it [perl #96942].

       ·   "caller" no longer leaks memory when called from the DB package if @DB::args was assigned to after the
           first call to "caller".  Carp was triggering this bug [perl #97010]. (5.14.2)

       ·   "close" and similar filehandle functions, when called on built-in global variables (like $+), used to die
           if the variable happened to hold the undefined value, instead of producing the usual "Use of uninitialized
           value" warning.

       ·   When autovivified file handles were introduced in Perl 5.6.0, "readline" was inadvertently made to
           autovivify when called as "readline($foo)" (but not as "<$foo>").  It has now been fixed never to
           autovivify.

       ·   Calling an undefined anonymous subroutine (e.g., what $x holds after "undef &{$x = sub{}}") used to cause
           a "Not a CODE reference" error, which has been corrected to "Undefined subroutine called" [perl #71154].

       ·   Causing @DB::args to be freed between uses of "caller" no longer results in a crash [perl #93320].

       ·   "setpgrp($foo)" used to be equivalent to "($foo, setpgrp)", because "setpgrp" was ignoring its argument if
           there was just one.  Now it is equivalent to "setpgrp($foo,0)".

       ·   "shmread" was not setting the scalar flags correctly when reading from shared memory, causing the existing
           cached numeric representation in the scalar to persist [perl #98480].

       ·   "++" and "--" now work on copies of globs, instead of dying.

       ·   "splice()" doesn't warn when truncating

           You can now limit the size of an array using "splice(@a,MAX_LEN)" without worrying about warnings.

       ·   $$ is no longer tainted.  Since this value comes directly from "getpid()", it is always safe.


       ·   On Win32, a number of tests hang unless STDERR is redirected.  The cause of this is still under
           investigation.

       ·   When building as root with a umask that prevents files from being other-readable, t/op/filetest.t will
           fail.  This is a test bug, not a bug in perl's behavior.

       ·   Configuring with a recent gcc and link-time-optimization, such as "Configure -Doptimize='-O2 -flto'" fails
           because the optimizer optimizes away some of Configure's tests.  A workaround is to omit the "-flto" flag
           when running Configure, but add it back in while actually building, something like

               sh Configure -Doptimize=-O2
               make OPTIMIZE='-O2 -flto'

       ·   The following CPAN modules have test failures with perl 5.16.  Patches have been submitted for all of
           these, so hopefully there will be new releases soon:

           ·   Date::Pcalc version 6.1

           ·   Module::CPANTS::Analyse version 0.85

               This fails due to problems in Module::Find 0.10 and File::MMagic 1.27.

           ·   PerlIO::Util version 0.72

Acknowledgements
       Perl 5.16.0 represents approximately 12 months of development since Perl 5.14.0 and contains approximately
       590,000 lines of changes across 2,500 files from 139 authors.

       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 5.16.0:

       Aaron Crane, Abhijit Menon-Sen, Abigail, Alan Haggai Alavi, Alberto Simo~es, Alexandr Ciornii, Andreas Koenig,
       Andy Dougherty, Aristotle Pagaltzis, Bo Johansson, Bo Lindbergh, Breno G. de Oliveira, brian d foy, Brian
       Fraser, Brian Greenfield, Carl Hayter, Chas. Owens, Chia-liang Kao, Chip Salzenberg, Chris 'BinGOs' Williams,
       Christian Hansen, Christopher J. Madsen, chromatic, Claes Jacobsson, Claudio Ramirez, Craig A. Berry, Damian
       Conway, Daniel Kahn Gillmor, Darin McBride, Dave Rolsky, David Cantrell, David Golden, David Leadbeater, David
       Mitchell, Dee Newcum, Dennis Kaarsemaker, Dominic Hargreaves, Douglas Christopher Wilson, Eric Brine, Father
       Chrysostomos, Florian Ragwitz, Frederic Briere, George Greer, Gerard Goossen, Gisle Aas, H.Merijn Brand,
       Hojung Youn, Ian Goodacre, James E Keenan, Jan Dubois, Jerry D. Hedden, Jesse Luehrs, Jesse Vincent, Jilles
       Tjoelker, Jim Cromie, Jim Meyering, Joel Berger, Johan Vromans, Johannes Plunien, John Hawkinson, John P.
       Linderman, John Peacock, Joshua ben Jore, Juerd Waalboer, Karl Williamson, Karthik Rajagopalan, Keith
       Thompson, Kevin J.  Woolley, Kevin Ryde, Laurent Dami, Leo Lapworth, Leon Brocard, Leon Timmermans, Louis
       Strous, Lukas Mai, Marc Green, Marcel Gruenauer, Mark A.  Stratman, Mark Dootson, Mark Jason Dominus, Martin
       Hasch, Matthew Horsfall, Max Maischein, Michael G Schwern, Michael Witten, Mike Sheldrake, Moritz Lenz,
       Nicholas Clark, Niko Tyni, Nuno Carvalho, Pau Amma, Paul Evans, Paul Green, Paul Johnson, Perlover, Peter John
       Acklam, Peter Martini, Peter Scott, Phil Monsen, Pino Toscano, Rafael Garcia-Suarez, Rainer Tammer, Reini
       Urban, Ricardo Signes, Robin Barker, Rodolfo Carvalho, Salvador Fandin~o, Sam Kimbrel, Samuel Thibault, Shawn
       M Moore, Shigeya Suzuki, Shirakata Kentaro, Shlomi Fish, Sisyphus, Slaven Rezic, Spiros Denaxas, Steffen
       Mueller, Steffen Schwigon, Stephen Bennett, Stephen Oberholtzer, Stevan Little, Steve Hay, Steve Peters,
       Thomas Sibley, Thorsten Glaser, Timothe Litt, Todd Rinaldo, Tom Christiansen, Tom Hukins, Tony Cook, Vadim
       Konovalov, Vincent Pit, Vladimir Timofeev, Walt Mankowski, Yves Orton, Zefram, Zsban Ambrus, var Arnfjoer`
       Bjarmason.

       newsgroup and the perl bug database at <http://rt.perl.org/perlbug/>.  There may also be information at
       <http://www.perl.org/>, the Perl Home Page.

       If you believe you have an unreported bug, please run the perlbug program included with your release.  Be sure
       to trim your bug down to a tiny but sufficient test case.  Your bug report, along with the output of "perl
       -V", will be sent off to [email protected] to be 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 [email protected].  This points to a closed
       subscription unarchived mailing list, which includes all core committers, who will be able to help assess the
       impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the
       problem across all platforms on which Perl is supported.  Please use this address only for security issues in
       the Perl core, not for modules independently distributed on CPAN.

SEE ALSO
       The Changes file for an explanation of how to view exhaustive details on what changed.

       The INSTALL file for how to build Perl.

       The README file for general stuff.

       The Artistic and Copying files for copyright information.



perl v5.16.3                                          2013-03-04                                     PERL5160DELTA(1)