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

Notice

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

Core Enhancements

Unicode

Unicode Version 6.0 is now supported (mostly)

Perl comes with the Unicode 6.0 data base updated withCorrigendum #8,with one exception noted below.See http://unicode.org/versions/Unicode6.0.0/ for details on the newrelease. Perl does not support any Unicode provisional properties,including the new ones for this release.

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

Full functionality for `use feature 'unicode_strings'`

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

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

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

\N{NAME} and charnames::vianame now know about the abbreviatedcharacter names listed by Unicode, such as NBSP, SHY, LRO, ZWJ, etc.; allcustomary abbreviations for the C0 and C1 control characters (such asACK, BEL, CAN, etc.); and a few new variants of some C1 full names thatare in common usage.
Unicode has several named character sequences, in which particular sequencesof code points are given names. \N{NAME} now recognizes these.
\N{NAME}, charnames::vianame, and charnames::viacodenow know about every character in Unicode. In earlier releases ofPerl, they didn't know about the Hangul syllables nor severalCJK (Chinese/Japanese/Korean) characters.
It is now possible to override Perl's abbreviations with your own custom aliases.
You can now create a custom alias of the ordinal of acharacter, known by \N{NAME}, charnames::vianame(), andcharnames::viacode(). Previously, aliases had to be to officialUnicode character names. This made it impossible to create an alias forunnamed code points, such as those reserved for privateuse.
The new function charnames::string_vianame() is a run-time versionof \N{NAME}}, returning the string of characters whose Unicodename is its parameter. It can handle Unicode named charactersequences, whereas the pre-existing charnames::vianame() cannot,as the latter returns a single code point.

See charnames for details on all these changes.

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

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

Any unsigned value can be encoded as a character

With this release, Perl is adopting a model that any unsigned valuecan be treated as a code point and encoded internally (as utf8)without warnings, not just the code points that are legal in Unicode.However, unless utf8 or the corresponding sub-category (see previousitem) of lexical warnings have been explicitly turned off, outputtingor executing a Unicode-defined operation such as upper-casingon such a code point generates a warning. Attempting to input theseusing strict rules (such as with the :encoding(UTF-8) layer)will continue to fail. Prior to this release, handling wasinconsistent and in places, incorrect.

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

Unicode database files not installed

The Unicode database files are no longer installed with Perl. Thisdoesn't affect any functionality in Perl and saves significant diskspace. If you need these files, you can download them fromhttp://www.unicode.org/Public/zipped/6.0.0/.

Regular Expressions

`(?^...)` construct signifies default modifiers

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

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

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

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

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

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

The /l modifier says to compile the regular expression as if it werein the scope of use locale, even if it is not.
The /u modifier says to compile the regular expression as if it werein the scope of a use feature 'unicode_strings' pragma.
The /d (default) modifier is used to override any use locale anduse feature 'unicode_strings' pragmas in effect at the timeof compiling the regular expression.
The /a regular expression modifier restricts \s, \d and \w andthe POSIX ([[:posix:]]) character classes to the ASCII range. Theircomplements and \b and \B are correspondinglyaffected. Otherwise, /a behaves like the /u modifier, in thatcase-insensitive matching uses Unicode semantics.
If the /a modifier is repeated, then additionally in case-insensitivematching, no ASCII character can match a non-ASCII character.For example,
```
 "k" =~ /\N{KELVIN SIGN}/ai
  "\xDF" =~ /ss/ai
 
```
match but
```
 "k" =~ /\N{KELVIN SIGN}/aai
  "\xDF" =~ /ss/aai
 
```
do not match.

See Modifiers in perlre for more detail.

Non-destructive substitution

The substitution (s///) and transliteration(y///) operators now support an /r option thatcopies the input variable, carries out the substitution onthe copy, and returns the result. The original remains unmodified.

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

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

Re-entrant regular expression engine

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

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

`use re '/flags'`

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

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

See '/flags' mode in re for details.

\o{...} for octals

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

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

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

Regular expression debugging output improvement

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

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

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

Syntactical Enhancements

Array and hash container functions accept references

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

All builtin functions that operate directly on array or hashcontainers now also accept unblessed hard references to arraysor hashes:

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

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

  push @{$obj->tags}, $new_tag;  # old way
   push $obj->tags, $new_tag;  # new way
 
   for ( keys %{$hoh->{genres}{artists}} ) {...} # old way 
   for ( keys $hoh->{genres}{artists} ) {...} # new way

Single term prototype

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

`package` block syntax

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

Statement labels can appear in more places

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

Stacked labels

Multiple statement labels can now appear before a single statement.

Uppercase X/B allowed in hexadecimal/binary literals

Literals may now use either upper case 0X... or 0B... prefixes,in addition to the already supported 0x... and 0b...syntax [perl #76296].

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

Overridable tie functions

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

Exception Handling

To make them more reliable and consistent, several changes have been madeto how die, warn, and $@ behave.

When an exception is thrown inside an eval, the exception is nolonger at risk of being clobbered by destructor code running during unwinding.Previously, the exception was written into $@early in the throwing process, and would be overwritten if eval wasused internally in the destructor for an object that had to be freedwhile exiting from the outer eval. Now the exception is writteninto $@ last thing before exiting the outer eval, so the coderunning immediately thereafter can rely on the value in $@ correctlycorresponding to that eval. ($@ is still also set before exiting theeval, for the sake of destructors that rely on this.)
Likewise, a local $@ inside an eval no longer clobbers anyexception thrown in its scope. Previously, the restoration of $@ uponunwinding would overwrite any exception being thrown. Now the exceptiongets to the eval anyway. So local $@ is safe before a die.
Exceptions thrown from object destructors no longer modify the $@of the surrounding context. (If the surrounding context was exceptionunwinding, this used to be another way to clobber the exception beingthrown.) Previously such an exception wassometimes emitted as a warning, and then either wasstring-appended to the surrounding $@ or completely replaced thesurrounding $@, depending on whether that exception and the surrounding$@ were strings or objects. Now, an exception in this situation isalways emitted as a warning, leaving the surrounding $@ untouched.In addition to object destructors, this also affects any function callrun by XS code using the G_KEEPERR flag.
Warnings for warn can now be objects in the same way as exceptionsfor die. If an object-based warning gets the default handlingof writing to standard error, it is stringified as before with thefilename and line number appended. But a $SIG{__WARN__} handler nowreceives an object-based warning as an object, where previously itwas passed the result of stringifying the object.

Other Enhancements

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

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

srand() now returns the seed

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

printf-like functions understand post-1980 size modifiers

Perl's printf and sprintf operators, and Perl's internal printf replacementfunction, now understand the C90 size modifiers "hh" (char), "z"(size_t), and "t" (ptrdiff_t). Also, when compiled with a C99compiler, Perl now understands the size modifier "j" (intmax_t) (but this is not portable).

So, for example, on any modern machine, sprintf("%hhd", 257) returns "1".

New global variable `${^GLOBAL_PHASE}`

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

`-d:-foo` calls `Devel::foo::unimport`

The syntax -d:foo was extended in 5.6.1 to make -d:foo=barequivalent to -MDevel::foo=bar, which expandsinternally to use Devel::foo 'bar'.Perl now allows prefixing the module name with -, with the samesemantics as -M; that is:

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

This is particularly useful for suppressing the default actions of aDevel::* module's import method whilst still loading it for debugging.

Filehandle method calls load IO::File on demand

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

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

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

  STDOUT->autoflush(1);

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

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

Improved IPv6 support

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

DTrace probes now include package name

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

For example, using the following DTrace script:

  perl$target:::sub-entry
   {
   printf("%s::%s\n", copyinstr(arg0), copyinstr(arg3));
   }

and then running:

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

DTrace will print:

  main::test

New C APIs

See Internal Changes.

Security

User-defined regular expression properties

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

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

Incompatible Changes

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

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

Regular Expressions and String Escapes

Inverted bracketed character classes and multi-character folds

Some characters match a sequence of two or three characters in /iregular expression matching under Unicode rules. One example isLATIN SMALL LETTER SHARP S which matches the sequence ss.

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

This, however, can lead to very counter-intuitive results, especiallywhen inverted. Because of this, Perl 5.14 does not use multi-character /imatching in inverted character classes.

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

This should match any sequences of characters that aren't the SHARP Snor what SHARP S matches under /i. "s" isn't SHARP S, butUnicode says that "ss" is what SHARP S matches under /i. Sowhich one "wins"? Do you fail the match because the string has ss oraccept it because it has an s followed by another s?

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

\400-\777

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

Use of \400-\777 in the command-line option -0 retain theirconventional meaning. They slurp whole input files; previously, thiswas documented only for -0777.

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

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

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

 m/\p{ASCII_Hex_Digit}+/i

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

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

\p{} implies Unicode semantics

Specifying a Unicode property in the pattern indicatesthat the pattern is meant for matching according to Unicode rules, the way\N{NAME} does.

Regular expressions retain their localeness when interpolated

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

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

Stringification of regexes has changed

Default regular expression modifiers are now notated using(?^...). Code relying on the old stringification will fail. This is so that when new modifiers are added, such code won'thave to keep changing each time this happens, because the stringification will automatically incorporate the new modifiers.

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

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

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

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

And then use $modifiers instead of -xism.

Run-time code blocks in regular expressions inherit pragmata

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

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

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

Stashes and Package Variables

Localised tied hashes and arrays are no longed tied

In the following:

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

Earlier versions of Perl incorrectly tied the new local array. This hasnow been fixed. This fix could however potentially cause a change inbehaviour of some code.

Stashes are now always defined

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

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

Calling defined on a stash has been deprecated since 5.6.0, warned onlexicals since 5.6.0, and warned for stashes and other packagevariables since 5.12.0. defined %hash has always exposed animplementation detail: emptying a hash by deleting all entries from it doesnot make defined %hash false. Hence defined %hash is not valid code todetermine whether an arbitrary hash is empty. Instead, use the behaviourof an empty %hash always returning false in scalar context.

Clearing stashes

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

Dereferencing typeglobs

If you assign a typeglob to a scalar variable:

 $glob = *foo;

the glob that is copied to $glob is marked with a special flagindicating that the glob is just a copy. This allows subsequentassignments to $glob to overwrite the glob. The original glob,however, is immutable.

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

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

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

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

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

See http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810 formore detail.

Magic variables outside the main package

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

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

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

local($_) strips all magic from $_

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

Therefore, as an exception to the general rule, local($_) will notonly assign a new value to $_, but also remove all existing magic fromit as well.

Parsing of package and variable names

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

Regardless of this change, the exact parsing of package separators hasnever been guaranteed and is subject to change in future Perl versions.

Changes to Syntax or to Perl Operators

`given` return values

given blocks now return the last evaluatedexpression, or an empty list if the block was exited by break. Thus youcan now write:

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

See Return value in perlsyn for details.

Change in parsing of certain prototypes

Functions declared with the following prototypes now behave correctly as unaryfunctions:

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

Due to this bug fix [perl #75904], functionsusing the (*), (;$) and (;*) prototypesare parsed with higher precedence than before. Soin the following example:

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

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

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

Smart-matching against array slices

Previously, the following code resulted in a successful match:

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

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

Negation treats strings differently from before

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

Negative zero

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

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

`:=` is now a syntax error

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

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

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

Change in the parsing of identifiers

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

Threads and Processes

Directory handles not copied to threads

On systems other than Windows that do not havea fchdir function, newly-created threads nolonger inherit directory handles from their parent threads. Such programswould usually have crashed anyway [perl #75154].

`close` on shared pipes

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

fork() emulation will not wait for signalled children

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

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

See perlfork for more information about the fork() emulation onWindows.

Configuration

Naming fixes in Policy_sh.SH may invalidate Policy.sh

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

This will change the behaviour of Policy.sh if you happen to have beenaccidentally relying on its incorrect behaviour.

Perl source code is read in text mode on Windows

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

The default build options for Windows have been changed to read Perl sourcecode on Windows in text mode now. ByteLoader will (hopefully) be updated onCPAN to automatically handle this situation [perl #28106].

Deprecations

Omitting a space between a regular expression and subsequent word

Omitting the space between a regular expression operator orits modifiers and the following word is deprecated. Forexample, m/foo/sand $bar is for now still parsedas m/foo/s and $bar, but will now issue a warning.

`\cX`

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

`"\b{"` and `"\B{"`

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

Perl 4-era .pl libraries

Perl bundles a handful of library files that predate Perl 5.This bundling is now deprecated for most of these files, which are nowavailable from CPAN. The affected files now warn when run, if they wereinstalled as part of the core.

This is a mandatory warning, not obeying -X or lexical warning bits.The warning is modelled on that supplied by deprecate.pm fordeprecated-in-core .pm libraries. It points to the specific CPANdistribution that contains the .pl libraries. The CPAN versions, ofcourse, do not generate the warning.

List assignment to `$[`

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

Use of qw(...) as parentheses

Historically the parser fooled itself into thinking that qw(...) literalswere always enclosed in parentheses, and as a result you could sometimes omitparentheses around them:

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

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

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

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

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

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

where parentheses were never required around the expression.

`\N{BELL}`

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

`?PATTERN?`

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

Tie functions on scalars holding typeglobs

Calling a tie function (tie, tied, untie) with a scalar argumentacts on a filehandle if the scalar happens to hold a typeglob.

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

Now there is a deprecation warning whenever a tiefunction is used on a handle without an explicit *.

User-defined case-mapping

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

Deprecated modules

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

If you ship a packaged version of Perl, either alone or as part of alarger system, then you should carefully consider the repercussions ofcore module deprecations. You may want to consider shipping your defaultbuild of Perl with a package for the deprecated module thatinstalls into vendor or site Perl library directories. This willinhibit the deprecation warnings.

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

You can silence these deprecation warnings by installing the modulein question from CPAN. To install the latest version of it by rolerather than by name, just install Task::Deprecations::5_14.

Devel::DProf
We strongly recommend that you install and use Devel::NYTProf insteadof Devel::DProf, as Devel::NYTProf offers significantlyimproved profiling and reporting.

Performance Enhancements

"Safe signals" optimisation

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

Optimisation of shift() and pop() calls without arguments

Two fewer OPs are used for shift() and pop() calls with no argument (withimplicit @_). This change makes shift() 5% faster than shift @_on non-threaded perls, and 25% faster on threaded ones.

Optimisation of regexp engine string comparison work

The foldEQ_utf8 API function for case-insensitive comparison of strings (whichis used heavily by the regexp engine) was substantially refactored andoptimised -- and its documentation much improved as a free bonus.

Regular expression compilation speed-up

Compiling regular expressions has been made faster when upgradingthe regex to utf8 is necessary but this isn't known when the compilation begins.

String appending is 100 times faster

When doing a lot of string appending, perls built to use the system'smalloc could end up allocating a lot more memory than needed in ainefficient way.

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

Eliminate `PL_*` accessor functions under ithreads

When MULTIPLICITY was first developed, and interpreter state moved intoan interpreter struct, thread- and interpreter-local PL_* variableswere defined as macros that called accessor functions (returning theaddress of the value) outside the Perl core. The intent was to allowmembers within the interpreter struct to change size without breakingbinary compatibility, so that bug fixes could be merged to a maintenancebranch that necessitated such a size change. This mechanism was redundantand penalised well-behaved code. It has been removed.

Freeing weak references

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

Lexical array and hash assignments

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

Now we have found another way to speed up these assignments [perl #82110].

`@_` uses less memory

Previously, @_ was allocated for every subroutine at compile time withenough space for four entries. Now this allocation is done on demand whenthe subroutine is called [perl #72416].

Size optimisations to SV and HV structures

xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash andon some systems will cause struct xpvhv to become cache-aligned. To avoidthis memory saving causing a slowdown elsewhere, boolean use of HvFILLnow calls HvTOTALKEYS instead (which is equivalent), so while the filldata when actually required are now calculated on demand, cases whenthis needs to be done should be rare.

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

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

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

Memory consumption improvements to Exporter

The @EXPORT_FAIL AV is no longer created unless needed, hence neither isthe typeglob backing it. This saves about 200 bytes for every package thatuses Exporter but doesn't use this functionality.

Memory savings for weak references

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

`%+` and `%-` use less memory

The bulk of the Tie::Hash::NamedCapture module used to be in the Perlcore. It has now been moved to an XS module to reduce overhead forprograms that do not use %+ or %-.

Multiple small improvements to threads

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

Adjacent pairs of nextstate opcodes are now optimized away

Previously, in code such as

 use constant DEBUG => 0;
 
  sub GAK {
  warn if DEBUG;
  print "stuff\n";
  }

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

The execution of a sequence of nextstate ops is indistinguishable from justthe last nextstate op so the peephole optimizer now eliminates the first ofa pair of nextstate ops except when the first carries a label, since labelsmust not be eliminated by the optimizer, and label usage isn't conclusively knownat compile time.

Modules and Pragmata

New Modules and Pragmata

CPAN::Meta::YAML 0.003 has been added as a dual-life module. It supports asubset of YAML sufficient for reading and writing META.yml and MYMETA.yml filesincluded with CPAN distributions or generated by the module installationtoolchain. It should not be used for any other general YAML parsing orgeneration task.
CPAN::Meta version 2.110440 has been added as a dual-life module. Itprovides a standard library to read, interpret and write CPAN distributionmetadata files (like META.json and META.yml) that describe adistribution, its contents, and the requirements for building it andinstalling it. The latest CPAN distribution metadata specification isincluded as CPAN::Meta::Spec and notes on changes in the specificationover time are given in CPAN::Meta::History.
HTTP::Tiny 0.012 has been added as a dual-life module. It is a verysmall, simple HTTP/1.1 client designed for simple GET requests and filemirroring. It has been added so that CPAN.pm and CPANPLUS can"bootstrap" HTTP access to CPAN using pure Perl without relying on externalbinaries like curl(1) or wget(1).
JSON::PP 2.27105 has been added as a dual-life module to allow CPANclients to read META.json files in CPAN distributions.
Module::Metadata 1.000004 has been added as a dual-life module. It gatherspackage and POD information from Perl module files. It is a standalone modulebased on Module::Build::ModuleInfo for use by other module installationtoolchain components. Module::Build::ModuleInfo has been deprecated infavor of this module instead.
Perl::OSType 1.002 has been added as a dual-life module. It maps Perloperating system names (like "dragonfly" or "MSWin32") to more generic typeswith standardized names (like "Unix" or "Windows"). It has been refactoredout of Module::Build and ExtUtils::CBuilder and consolidates such mappings intoa single location for easier maintenance.
The following modules were added by the Unicode::Collate upgrade. See below for details.
Unicode::Collate::CJK::Big5
Unicode::Collate::CJK::GB2312
Unicode::Collate::CJK::JISX0208
Unicode::Collate::CJK::Korean
Unicode::Collate::CJK::Pinyin
Unicode::Collate::CJK::Stroke
Version::Requirements version 0.101020 has been added as a dual-lifemodule. It provides a standard library to model and manipulates moduleprerequisites and version constraints defined in CPAN::Meta::Spec.

Updated Modules and Pragma

attributes has been upgraded from version 0.12 to 0.14.
Archive::Extract has been upgraded from version 0.38 to 0.48.
Updates since 0.38 include: a safe print method that guardsArchive::Extract from changes to $\; a fix to the tests when run in corePerl; support for TZ files; a modification for the lzmalogic to favour IO::Uncompress::Unlzma; and a fixfor an issue with NetBSD-current and its new unzip(1)executable.
Archive::Tar has been upgraded from version 1.54 to 1.76.
Important changes since 1.54 include the following:
- Compatibility with busybox implementations of tar(1).
- A fix so that write() and create_archive()close only filehandles they themselves opened.
- A bug was fixed regarding the exit code of extract_archive.
- The ptar(1) utility has a new option to allow safe creation oftarballs without world-writable files on Windows, allowing thosearchives to be uploaded to CPAN.
- A new ptargrep(1) utility for using regular expressions against the contents of files in a tar archive.
- pax extended headers are now skipped.
Attribute::Handlers has been upgraded from version 0.87 to 0.89.
autodie has been upgraded from version 2.06_01 to 2.1001.
AutoLoader has been upgraded from version 5.70 to 5.71.
The B module has been upgraded from version 1.23 to 1.29.
It no longer crashes when taking apart a y/// containing charactersoutside the octet range or compiled in a use utf8 scope.
The size of the shared object has been reduced by about 40%, with noreduction in functionality.
B::Concise has been upgraded from version 0.78 to 0.83.
B::Concise marks rv2sv(), rv2av(), and rv2hv() ops with the newOPpDEREF flag as "DREFed".
It no longer produces mangled output with the -tree option[perl #80632].
B::Debug has been upgraded from version 1.12 to 1.16.
B::Deparse has been upgraded from version 0.96 to 1.03.
The deparsing of a nextstate op has changed when it has both achange of package relative to the previous nextstate, or a change of%^H or other state and a label. The label was previously emittedfirst, but is now emitted last (5.12.1).
The no 5.13.2 or similar form is now correctly handled by B::Deparse(5.12.3).
B::Deparse now properly handles the code that applies a conditionalpattern match against implicit $_ as it was fixed in [perl #20444].
Deparsing of our followed by a variable with funny characters(as permitted under the use utf8 pragma) has also been fixed [perl #33752].
B::Lint has been upgraded from version 1.11_01 to 1.13.
base has been upgraded from version 2.15 to 2.16.
Benchmark has been upgraded from version 1.11 to 1.12.
bignum has been upgraded from version 0.23 to 0.27.
Carp has been upgraded from version 1.15 to 1.20.
Carp now detects incomplete caller EXPRoverrides and avoids using bogus @DB::args. To provide backtraces,Carp relies on particular behaviour of the caller() builtin.Carp now detects if other code has overridden this with anincomplete implementation, and modifies its backtrace accordingly.Previously incomplete overrides would cause incorrect values inbacktraces (best case), or obscure fatal errors (worst case).
This fixes certain cases of "Bizarre copy of ARRAY" caused by modulesoverriding caller() incorrectly (5.12.2).
It now also avoids using regular expressions that cause Perl toload its Unicode tables, so as to avoid the "BEGIN not safe aftererrors" error that ensue if there has been a syntax error[perl #82854].
CGI has been upgraded from version 3.48 to 3.52.
This provides the following security fixes: the MIME boundary in multipart_init() is now random and the handling of newlines embedded in header values has been improved.
Compress::Raw::Bzip2 has been upgraded from version 2.024 to 2.033.
It has been updated to use bzip2(1) 1.0.6.
Compress::Raw::Zlib has been upgraded from version 2.024 to 2.033.
constant has been upgraded from version 1.20 to 1.21.
Unicode constants work once more. They have been broken since Perl 5.10.0[CPAN RT #67525].
CPAN has been upgraded from version 1.94_56 to 1.9600.
Major highlights:
- much less configuration dialog hassle
- support for META/MYMETA.json
- support for local::lib
- support for HTTP::Tiny to reduce the dependency on FTP sites
- automatic mirror selection
- iron out all known bugs in configure_requires
- support for distributions compressed with bzip2(1)
- allow Foo/Bar.pm on the command line to mean Foo::Bar
CPANPLUS has been upgraded from version 0.90 to 0.9103.
A change to cpanp-run-perlresolves RT #55964and RT #57106, bothof which related to failures to install distributions that useModule::Install::DSL (5.12.2).
A dependency on Config was not recognised as acore module dependency. This has been fixed.
CPANPLUS now includes support for META.json and MYMETA.json.
CPANPLUS::Dist::Build has been upgraded from version 0.46 to 0.54.
Data::Dumper has been upgraded from version 2.125 to 2.130_02.
The indentation used to be off when $Data::Dumper::Terse was set. Thishas been fixed [perl #73604].
This upgrade also fixes a crash when using custom sort functions that mightcause the stack to change [perl #74170].
Dumpxs no longer crashes with globs returned by *$io_ref[perl #72332].
DB_File has been upgraded from version 1.820 to 1.821.
DBM_Filter has been upgraded from version 0.03 to 0.04.
Devel::DProf has been upgraded from version 20080331.00 to 20110228.00.
Merely loading Devel::DProf now no longer triggers profiling to start.Both use Devel::DProf and perl -d:DProf ... behave as before and startthe profiler.
NOTE: Devel::DProf is deprecated and will be removed from a futureversion of Perl. We strongly recommend that you install and useDevel::NYTProf instead, as it offers significantly improvedprofiling and reporting.
Devel::Peek has been upgraded from version 1.04 to 1.07.
Devel::SelfStubber has been upgraded from version 1.03 to 1.05.
diagnostics has been upgraded from version 1.19 to 1.22.
It now renders pod links slightly better, and has been taught to finddescriptions for messages that share their descriptions with othermessages.
Digest::MD5 has been upgraded from version 2.39 to 2.51.
It is now safe to use this module in combination with threads.
Digest::SHA has been upgraded from version 5.47 to 5.61.
shasum now more closely mimics sha1sum(1)/md5sum(1).
addfile accepts all POSIX filenames.
New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS 180-4[February 2011])
DirHandle has been upgraded from version 1.03 to 1.04.
Dumpvalue has been upgraded from version 1.13 to 1.16.
DynaLoader has been upgraded from version 1.10 to 1.13.
It fixes a buffer overflow when passed a very long file name.
It no longer inherits from AutoLoader; hence it no longerproduces weird error messages for unsuccessful method calls on classes thatinherit from DynaLoader [perl #84358].
Encode has been upgraded from version 2.39 to 2.42.
Now, all 66 Unicode non-characters are treated the same way U+FFFF hasalways been treated: in cases when it was disallowed, all 66 aredisallowed, and in cases where it warned, all 66 warn.
Env has been upgraded from version 1.01 to 1.02.
Errno has been upgraded from version 1.11 to 1.13.
The implementation of Errno has been refactored to use about 55% less memory.
On some platforms with unusual header files, like Win32 gcc(1) using mingw64headers, some constants that weren't actually error numbers have been exposedby Errno. This has been fixed [perl #77416].
Exporter has been upgraded from version 5.64_01 to 5.64_03.
Exporter no longer overrides $SIG{__WARN__} [perl #74472]
ExtUtils::CBuilder has been upgraded from version 0.27 to 0.280203.
ExtUtils::Command has been upgraded from version 1.16 to 1.17.
ExtUtils::Constant has been upgraded from 0.22 to 0.23.
The AUTOLOAD helper code generated by ExtUtils::Constant::ProxySubscan now croak() for missing constants, or generate a complete AUTOLOADsubroutine in XS, allowing simplification of many modules that use it(Fcntl, File::Glob, GDBM_File, I18N::Langinfo, POSIX,Socket).
ExtUtils::Constant::ProxySubs can now optionally push the names of allconstants onto the package's @EXPORT_OK.
ExtUtils::Install has been upgraded from version 1.55 to 1.56.
ExtUtils::MakeMaker has been upgraded from version 6.56 to 6.57_05.
ExtUtils::Manifest has been upgraded from version 1.57 to 1.58.
ExtUtils::ParseXS has been upgraded from version 2.21 to 2.2210.
Fcntl has been upgraded from version 1.06 to 1.11.
File::Basename has been upgraded from version 2.78 to 2.82.
File::CheckTree has been upgraded from version 4.4 to 4.41.
File::Copy has been upgraded from version 2.17 to 2.21.
File::DosGlob has been upgraded from version 1.01 to 1.04.
It allows patterns containing literal parentheses: they no longer need tobe escaped. On Windows, it no longeradds an extra ./ to file namesreturned when the pattern is a relative glob with a drive specification,like C:*.pl [perl #71712].
File::Fetch has been upgraded from version 0.24 to 0.32.
HTTP::Lite is now supported for the "http" scheme.
The fetch(1) utility is supported on FreeBSD, NetBSD, andDragonfly BSD for the http and ftp schemes.
File::Find has been upgraded from version 1.15 to 1.19.
It improves handling of backslashes on Windows, so that paths likeC:\dir\/file are no longer generated [perl #71710].
File::Glob has been upgraded from version 1.07 to 1.12.
File::Spec has been upgraded from version 3.31 to 3.33.
Several portability fixes were made in File::Spec::VMS: a colon is nowrecognized as a delimiter in native filespecs; caret-escaped delimiters arerecognized for better handling of extended filespecs; catpath() returnsan empty directory rather than the current directory if the input directoryname is empty; and abs2rel() properly handles Unix-style input (5.12.2).
File::stat has been upgraded from 1.02 to 1.05.
The -x and -X file test operators now work correctly when runby the superuser.
Filter::Simple has been upgraded from version 0.84 to 0.86.
GDBM_File has been upgraded from 1.10 to 1.14.
This fixes a memory leak when DBM filters are used.
Hash::Util has been upgraded from 0.07 to 0.11.
Hash::Util no longer emits spurious "uninitialized" warnings whenrecursively locking hashes that have undefined values [perl #74280].
Hash::Util::FieldHash has been upgraded from version 1.04 to 1.09.
I18N::Collate has been upgraded from version 1.01 to 1.02.
I18N::Langinfo has been upgraded from version 0.03 to 0.08.
langinfo() now defaults to using $_ if there is no argument given, justas the documentation has always claimed.
I18N::LangTags has been upgraded from version 0.35 to 0.35_01.
if has been upgraded from version 0.05 to 0.0601.
IO has been upgraded from version 1.25_02 to 1.25_04.
This version of IO includes a new IO::Select, which now allows IO::Handleobjects (and objects in derived classes) to be removed from an IO::Select seteven if the underlying file descriptor is closed or invalid.
IPC::Cmd has been upgraded from version 0.54 to 0.70.
Resolves an issue with splitting Win32 command lines. An argumentconsisting of the single character "0" used to be omitted (CPAN RT #62961).
IPC::Open3 has been upgraded from 1.05 to 1.09.
open3() now produces an error if the exec call fails, allowing thiscondition to be distinguished from a child process that exited with anon-zero status [perl #72016].
The internal xclose() routine now knows how to handle file descriptors asdocumented, so duplicating STDIN in a child process using its filedescriptor now works [perl #76474].
IPC::SysV has been upgraded from version 2.01 to 2.03.
lib has been upgraded from version 0.62 to 0.63.
Locale::Maketext has been upgraded from version 1.14 to 1.19.
Locale::Maketext now supports external caches.
This upgrade also fixes an infinite loop inLocale::Maketext::Guts::_compile() whenworking with tainted values (CPAN RT #40727).
->maketext calls now back up and restore $@ so errormessages are not suppressed (CPAN RT #34182).
Log::Message has been upgraded from version 0.02 to 0.04.
Log::Message::Simple has been upgraded from version 0.06 to 0.08.
Math::BigInt has been upgraded from version 1.89_01 to 1.994.
This fixes, among other things, incorrect results when computing binomialcoefficients [perl #77640].
It also prevents sqrt($int) from crashing under use bigrat.[perl #73534].
Math::BigInt::FastCalc has been upgraded from version 0.19 to 0.28.
Math::BigRat has been upgraded from version 0.24 to 0.26_02.
Memoize has been upgraded from version 1.01_03 to 1.02.
MIME::Base64 has been upgraded from 3.08 to 3.13.
Includes new functions to calculate the length of encoded and decodedbase64 strings.
Now provides encode_base64url() and decode_base64url() functions to processthe base64 scheme for "URL applications".
Module::Build has been upgraded from version 0.3603 to 0.3800.
A notable change is the deprecation of several modules.Module::Build::Version has been deprecated and Module::Build nowrelies on the version pragma directly. Module::Build::ModuleInfo hasbeen deprecated in favor of a standalone copy called Module::Metadata.Module::Build::YAML has been deprecated in favor of CPAN::Meta::YAML.
Module::Build now also generates META.json and MYMETA.json filesin accordance with version 2 of the CPAN distribution metadata specification,CPAN::Meta::Spec. The older format META.yml and MYMETA.yml files arestill generated.
Module::CoreList has been upgraded from version 2.29 to 2.47.
Besides listing the updated core modules of this release, it also stops listingthe Filespec module. That module never existed in core. The scriptsgenerating Module::CoreList confused it with VMS::Filespec, which actuallyis a core module as of Perl 5.8.7.
Module::Load has been upgraded from version 0.16 to 0.18.
Module::Load::Conditional has been upgraded from version 0.34 to 0.44.
The mro pragma has been upgraded from version 1.02 to 1.07.
NDBM_File has been upgraded from version 1.08 to 1.12.
This fixes a memory leak when DBM filters are used.
Net::Ping has been upgraded from version 2.36 to 2.38.
NEXT has been upgraded from version 0.64 to 0.65.
Object::Accessor has been upgraded from version 0.36 to 0.38.
ODBM_File has been upgraded from version 1.07 to 1.10.
This fixes a memory leak when DBM filters are used.
Opcode has been upgraded from version 1.15 to 1.18.
The overload pragma has been upgraded from 1.10 to 1.13.
overload::Method can now handle subroutines that are themselves blessedinto overloaded classes [perl #71998].
The documentation has greatly improved. See Documentation below.
Params::Check has been upgraded from version 0.26 to 0.28.
The parent pragma has been upgraded from version 0.223 to 0.225.
Parse::CPAN::Meta has been upgraded from version 1.40 to 1.4401.
The latest Parse::CPAN::Meta can now read YAML and JSON files usingCPAN::Meta::YAML and JSON::PP, which are now part of the Perl core.
PerlIO::encoding has been upgraded from version 0.12 to 0.14.
PerlIO::scalar has been upgraded from 0.07 to 0.11.
A read() after a seek() beyond the end of the string no longer thinks ithas data to read [perl #78716].
PerlIO::via has been upgraded from version 0.09 to 0.11.
Pod::Html has been upgraded from version 1.09 to 1.11.
Pod::LaTeX has been upgraded from version 0.58 to 0.59.
Pod::Perldoc has been upgraded from version 3.15_02 to 3.15_03.
Pod::Simple has been upgraded from version 3.13 to 3.16.
POSIX has been upgraded from 1.19 to 1.24.
It now includes constants for POSIX signal constants.
The re pragma has been upgraded from version 0.11 to 0.18.
The use re '/flags' subpragma is new.
The regmust() function used to crash when called on a regular expressionbelonging to a pluggable engine. Now it croaks instead.
regmust() no longer leaks memory.
Safe has been upgraded from version 2.25 to 2.29.
Coderefs returned by reval() and rdo() are now wrapped viawrap_code_refs() (5.12.1).
This fixes a possible infinite loop when looking for coderefs.
It adds several version::vxs::* routines to the default share.
SDBM_File has been upgraded from version 1.06 to 1.09.
SelfLoader has been upgraded from 1.17 to 1.18.
It now works in taint mode [perl #72062].
The sigtrap pragma has been upgraded from version 1.04 to 1.05.
It no longer tries to modify read-only arguments when generating abacktrace [perl #72340].
Socket has been upgraded from version 1.87 to 1.94.
See Improved IPv6 support above.
Storable has been upgraded from version 2.22 to 2.27.
Includes performance improvement for overloaded classes.
This adds support for serialising code references that contain UTF-8 stringscorrectly. The Storable minor versionnumber changed as a result, meaning thatStorable users who set $Storable::accept_future_minor to a FALSE valuewill see errors (see FORWARD COMPATIBILITY in Storable for more details).
Freezing no longer gets confused if the Perl stack gets reallocatedduring freezing [perl #80074].
Sys::Hostname has been upgraded from version 1.11 to 1.16.
Term::ANSIColor has been upgraded from version 2.02 to 3.00.
Term::UI has been upgraded from version 0.20 to 0.26.
Test::Harness has been upgraded from version 3.17 to 3.23.
Test::Simple has been upgraded from version 0.94 to 0.98.
Among many other things, subtests without a plan or no_plan now have animplicit done_testing() added to them.
Thread::Semaphore has been upgraded from version 2.09 to 2.12.
It provides two new methods that give more control over the decrementing ofsemaphores: down_nb and down_force.
Thread::Queue has been upgraded from version 2.11 to 2.12.
The threads pragma has been upgraded from version 1.75 to 1.83.
The threads::shared pragma has been upgraded from version 1.32 to 1.37.
Tie::Hash has been upgraded from version 1.03 to 1.04.
Calling Tie::Hash->TIEHASH() used to loop forever. Now it croaks.
Tie::Hash::NamedCapture has been upgraded from version 0.06 to 0.08.
Tie::RefHash has been upgraded from version 1.38 to 1.39.
Time::HiRes has been upgraded from version 1.9719 to 1.9721_01.
Time::Local has been upgraded from version 1.1901_01 to 1.2000.
Time::Piece has been upgraded from version 1.15_01 to 1.20_01.
Unicode::Collate has been upgraded from version 0.52_01 to 0.73.
Unicode::Collate has been updated to use Unicode 6.0.0.
Unicode::Collate::Locale now supports a plethora of new locales: ar, be,bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig, ja, ko, ru, sq, se, sr, to, uk, zh, zh__big5han, zh__gb2312han, zh__pinyin, and zh__stroke.
The following modules have been added:
Unicode::Collate::CJK::Big5 for zh__big5han which makes tailoring of CJK Unified Ideographs in the order of CLDR's big5han ordering.
Unicode::Collate::CJK::GB2312 for zh__gb2312han which makestailoring of CJK Unified Ideographs in the order of CLDR's gb2312han ordering.
Unicode::Collate::CJK::JISX0208 which makes tailoring of 6355 kanji (CJK Unified Ideographs) in the JIS X 0208 order.
Unicode::Collate::CJK::Korean which makes tailoring of CJK Unified Ideographs in the order of CLDR's Korean ordering.
Unicode::Collate::CJK::Pinyin for zh__pinyin which makestailoring of CJK Unified Ideographs in the order of CLDR's pinyin ordering.
Unicode::Collate::CJK::Stroke for zh__stroke which makestailoring of CJK Unified Ideographs in the order of CLDR's stroke ordering.
This also sees the switch from using the pure-Perl version of thismodule to the XS version.
Unicode::Normalize has been upgraded from version 1.03 to 1.10.
Unicode::UCD has been upgraded from version 0.27 to 0.32.
A new function, Unicode::UCD::num(), has been added. This functionreturns the numeric value of the string passed it or undef if the stringin its entirety has no "safe" numeric value. (For more detail, and for thedefinition of "safe", see num() in Unicode::UCD.)
This upgrade also includes several bug fixes:
- charinfo()
  - It is now updated to Unicode Version 6.0.0 with Corrigendum #8, excepting that, just as with Perl 5.14, the code point at U+1F514 has no name.
  - Hangul syllable code points have the correct names, and theirdecompositions are always output without requiring Lingua::KO::Hangul::Utilto be installed.
  - CJK (Chinese-Japanese-Korean) code points U+2A700 to U+2B734and U+2B740 to U+2B81D are now properly handled.
  - Numeric values are now output for those CJK code points that have them.
  - Names output for code points with multiple aliases are now thecorrected ones.
- charscript()
  This now correctly returns "Unknown" instead of undef for the scriptof a code point that hasn't been assigned another one.
- charblock()
  This now correctly returns "No_Block" instead of undef for the blockof a code point that hasn't been assigned to another one.
The version pragma has been upgraded from 0.82 to 0.88.
Because of a bug, now fixed, the is_strict() and is_lax() functions did notwork when exported (5.12.1).
The warnings pragma has been upgraded from version 1.09 to 1.12.
Calling use warnings without arguments is now significantly more efficient.
The warnings::register pragma has been upgraded from version 1.01 to 1.02.
It is now possible to register warning categories other than the names ofpackages using warnings::register. See perllexwarn(1) for more information.
XSLoader has been upgraded from version 0.10 to 0.13.
VMS::DCLsym has been upgraded from version 1.03 to 1.05.
Two bugs have been fixed [perl #84086]:
The symbol table name was lost when tying a hash, due to a thinko inTIEHASH. The result was that all tied hashes interacted with thelocal symbol table.
Unless a symbol table name had been explicitly specified in the callto the constructor, querying the special key :LOCAL failed toidentify objects connected to the local symbol table.
The Win32 module has been upgraded from version 0.39 to 0.44.
This release has several new functions: Win32::GetSystemMetrics(),Win32::GetProductInfo(), Win32::GetOSDisplayName().
The names returned by Win32::GetOSName() and Win32::GetOSDisplayName()have been corrected.
XS::Typemap has been upgraded from version 0.03 to 0.05.

Removed Modules and Pragmata

As promised in Perl 5.12.0's release notes, the following modules havebeen removed from the core distribution, and if needed should be installedfrom CPAN instead.

Class::ISA has been removed from the Perl core. Prior version was 0.36.
Pod::Plainer has been removed from the Perl core. Prior version was 1.02.
Switch has been removed from the Perl core. Prior version was 2.16.

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

Documentation

New Documentation

perlgpl

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

Perl 5.12.x delta files

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

perlpodstyle

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

perlsource, perlinterp, perlhacktut, and perlhacktips

See perlhack and perlrepository revamp, below.

Changes to Existing Documentation

perlmodlib is now complete

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

Replace incorrect tr/// table in perlebcdic

perlebcdic contains a helpful table to use in tr/// to convertbetween EBCDIC and Latin1/ASCII. The table was the inverse of the oneit describes, though the code that used the table worked correctly forthe specific example given.

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

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

Tricks for user-defined casing

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

INSTALL explicitly states that Perl requires a C89 compiler

This was already true, but it's now Officially Stated For The Record(5.12.2).

Explanation of `\xHH` and `\oOOO` escapes

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

-0NNN switch

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

Maintenance policy

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

Deprecation policy

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

New descriptions in perldiag

The following existing diagnostics are now documented:

perlbook

perlbook has been expanded to cover many more popular books.

`SvTRUE` macro

The documentation for the SvTRUE macro inperlapi was simply wrong in stating thatget-magic is not processed. It has been corrected.

op manipulation functions

Several API functions that process optrees have been newly documented.

perlvar revamp

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

Array and hash slices in scalar context

These are now documented in perldata.

`use locale` and formats

perlform and perllocale have been corrected to state thatuse locale affects formats.

overload

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

perlhack and perlrepository revamp

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

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

Time::Piece examples

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

Diagnostics

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

New Diagnostics

New Errors

Closure prototype called
This error occurs when a subroutine reference passed to an attributehandler is called, if the subroutine is a closure [perl #68560].
Insecure user-defined property %s
Perl detected tainted data when trying to compile a regularexpression that contains a call to a user-defined character propertyfunction, meaning \p{IsFoo} or \p{InFoo}.See User-Defined Character Properties in perlunicode and perlsec.
panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
This new error is triggered if a destructor called on an object in atypeglob that is being freed creates a new typeglob entry containing anobject with a destructor that creates a new entry containing an object etc.
Parsing code internal error (%s)
This new fatal error is produced when parsingcode supplied by an extension violates theparser's API in a detectable way.
refcnt: fd %d%s
This new error only occurs if a internal consistency check fails when apipe is about to be closed.
Regexp modifier "/%c" may not appear twice
The regular expression pattern has one of themutually exclusive modifiers repeated.
Regexp modifiers "/%c" and "/%c" are mutually exclusive
The regular expression pattern has more than one of the mutuallyexclusive modifiers.
Using !~ with %s doesn't make sense
This error occurs when !~ is used with s///r or y///r.

New Warnings

"\b{" is deprecated; use "\b\{" instead
"\B{" is deprecated; use "\B\{" instead
Use of an unescaped "{" immediately following a \b or \B is nowdeprecated in order to reserve its use for Perl itself in a future release.
Operation "%s" returns its argument for ...
Performing an operation requiring Unicode semantics (such as case-folding)on a Unicode surrogate or a non-Unicode character now triggers thiswarning.
Use of qw(...) as parentheses is deprecated
See Use of qw(...) as parentheses, above, for details.

Changes to Existing Diagnostics

The "Variable $foo is not imported" warning that precedes astrict 'vars' error has now been assigned the "misc" category, so thatno warnings will suppress it [perl #73712].
warn() and die() now produce "Wide character" warnings when fed acharacter outside the byte range if STDERR is a byte-sized handle.
The "Layer does not match this perl" error message has been replaced withthese more helpful messages [perl #73754]:
- PerlIO layer function table size (%d) does not match size expected by thisperl (%d)
- PerlIO layer instance size (%d) does not match size expected by this perl(%d)
The "Found = in conditional" warning that is emitted when a constant isassigned to a variable in a condition is now withheld if the constant isactually a subroutine or one generated by use constant, since the valueof the constant may not be known at the time the program is written[perl #77762].
Previously, if none of the gethostbyaddr(), gethostbyname() andgethostent() functions were implemented on a given platform, they wouldall die with the message "Unsupported socket function 'gethostent' called",with analogous messages for getnet*() and getserv*(). This has beencorrected.
The warning message about unrecognized regular expression escapes passedthrough has been changed to include any literal "{" following thetwo-character escape. For example, "\q{" is now emitted instead of "\q".

Utility Changes

perlbug(1)

perlbug now looks in the EMAIL environment variable for a return addressif the REPLY-TO and REPLYTO variables are empty.
perlbug did not previously generate a "From:" header, potentiallyresulting in dropped mail; it now includes that header.
The user's address is now used as the Return-Path.
Many systems these days don't have a valid Internet domain name, [email protected] does not accept email with a return-path that doesnot resolve. So the user's address is now passed to sendmail so it'sless likely to get stuck in a mail queue somewhere [perl #82996].
perlbug now always gives the reporter a chance to change the emailaddress it guesses for them (5.12.2).
perlbug should no longer warn about uninitialized values when using the -dand -v options (5.12.2).

perl5db.pl

The remote terminal works after forking and spawns new sessions, oneper forked process.

ptargrep

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

Configuration and Compilation

CCINCDIR and CCLIBDIR for the mingw64 cross-compiler are now correctlyunder $(CCHOME)\mingw\include and \lib rather than immediately below$(CCHOME).
This means the "incpath", "libpth", "ldflags", "lddlflags" and"ldflags_nolargefiles" values in Config.pm and Config_heavy.pl are nowset correctly.
make test.valgrind has been adjusted to account for cpan/dist/extseparation.
On compilers that support it, -Wwrite-strings is now added to cflags bydefault.
The Encode module can now (once again) be included in a static Perlbuild. The special-case handling for this situation got broken in Perl5.11.0, and has now been repaired.
The previous default size of a PerlIO buffer (4096 bytes) has been increasedto the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doublingthis decade-old default increases read and write performance by around25% to 50% when using the default layers of perlio on top of unix. To choosea non-default size, such as to get back the old value or to obtain an evenlarger value, configure with:
```
 ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
 
```
where N is the desired size in bytes; it should probably be a multiple ofyour page size.
An "incompatible operand types" error in ternary expressions when buildingwith clang has been fixed (5.12.2).
Perl now skips setuid File::Copy tests on partitions it detects mountedas nosuid (5.12.2).

Platform Support

New Platforms

AIX
Perl now builds on AIX 4.2 (5.12.1).

Discontinued Platforms

Apollo DomainOS
The last vestiges of support for this platform have been excised fromthe Perl distribution. It was officially discontinued in version 5.12.0.It had not worked for years before that.
MacOS Classic
The last vestiges of support for this platform have been excised from thePerl distribution. It was officially discontinued in an earlier version.

Platform-Specific Notes

AIX

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

ARM

The d_u32align configuration probe on ARM has been fixed (5.12.2).

Cygwin

MakeMaker has been updated to build manpages on cygwin.
Improved rebase behaviour
If a DLL is updated on cygwin the old imagebase address is reused.This solves most rebase errors, especially when updating on core DLL's.See http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README for more information.
Support for the standard cygwin dll prefix (needed for FFIs)
Updated build hints file

FreeBSD 7

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

HP-UX

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

IRIX

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

Mac OS X

Early versions of Mac OS X (Darwin) had buggy implementations of thesetregid(), setreuid(), setrgid(,) and setruid() functions, so Perlwould pretend they did not exist.
These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) andhigher, as they have been fixed [perl #72990].

MirBSD

Previously if you built Perl with a shared libperl.so on MirBSD (thedefault config), it would work up to the installation; however, onceinstalled, it would be unable to find libperl. Path handling is nowtreated as in the other BSD dialects.

NetBSD

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

OpenBSD

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

OpenVOS

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

Solaris

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

VMS

Extension building on older (pre 7.3-2) VMS systems was broken becauseconfigure.com hit the DCL symbol length limit of 1K. We now work withinthis limit when assembling the list of extensions in the core build (5.12.1).
We fixed configuring and building Perl with -Uuseperlio (5.12.1).
PerlIOUnix_open now honours the default permissions on VMS.
When perlio became the default and unix became the default bottom layer,the most common path for creating files from Perl became PerlIOUnix_open,which has always explicitly used 0666 as the permission mask. This preventsinheriting permissions from RMS defaults and ACLs, so to avoid that problem,we now pass 0777 to open(). In the VMS CRTL, 0777 has a specialmeaning over and above intersecting with the current umask; specifically, itallows Unix syscalls to preserve native default permissions (5.12.3).
The shortening of symbols longer than 31 characters in the core C sourcesand in extensions is now by default done by the C compiler rather than byxsubpp (which could only do so for generated symbols in XS code). You canreenable xsubpp's symbol shortening by configuring with -Uuseshortenedsymbols,but you'll have some work to do to get the core sources to compile.
Record-oriented files (record format variable or variable with fixed control)opened for write by the perlio layer will now be line-buffered to prevent theintroduction of spurious line breaks whenever the perlio buffer fills up.
git_version.h is now installed on VMS. This was an oversight in v5.12.0 whichcaused some extensions to fail to build (5.12.2).
Several memory leaks in stat FILEHANDLE have been fixed (5.12.2).
A memory leak in Perl_rename() due to a double allocation has beenfixed (5.12.2).
A memory leak in vms_fid_to_name() (used by realpath() andrealname()> has been fixed (5.12.2).

Windows

Fixed build process for SDK2003SP1 compilers.
Compilation with Visual Studio 2010 is now supported.
When using old 32-bit compilers, the define _USE_32BIT_TIME_T is nowset in $Config{ccflags}. This improves portability when compilingXS extensions using new compilers, but for a Perl compiled with old 32-bitcompilers.
$Config{gccversion} is now set correctly when Perl is built using themingw64 compiler from http://mingw64.org [perl #73754].
When building Perl with the mingw64 x64 cross-compiler incpath,libpth, ldflags, lddlflags and ldflags_nolargefiles valuesin Config.pm and Config_heavy.pl were not previously being setcorrectly because, with that compiler, the include and lib directoriesare not immediately below $(CCHOME) (5.12.2).
The build process proceeds more smoothly with mingw and dmake whenC:\MSYS\bin is in the PATH, due to a Cwd fix.
Support for building with Visual C++ 2010 is now underway, but is not yetcomplete. See README.win32 or perlwin32 for more details.
The option to use an externally-supplied crypt(), or to build with nocrypt() at all, has been removed. Perl supplies its own crypt()implementation for Windows, and the political situation that requiredthis part of the distribution to sometimes be omitted is long gone.

Internal Changes

New APIs

CLONE_PARAMS structure added to ease correct thread creation

Modules that create threads should now create CLONE_PARAMS structuresby calling the new function Perl_clone_params_new(), and free them withPerl_clone_params_del(). This will ensure compatibility with any futurechanges to the internals of the CLONE_PARAMS structure layout, and thatit is correctly allocated and initialised.

New parsing functions

Several functions have been added for parsing Perl statements andexpressions. These functions are meant to be used by XS code invokedduring Perl parsing, in a recursive-descent manner, to allow modules toaugment the standard Perl syntax.

parse_stmtseq()parses a sequence of statements, up to closing brace or EOF.
parse_fullstmt()parses a complete Perl statement, including optional label.
parse_barestmt()parses a statement without a label.
parse_block()parses a code block.
parse_label()parses a statement label, separate from statements.
parse_fullexpr() ,parse_listexpr() ,parse_termexpr() , andparse_arithexpr() parse expressions at various precedence levels.

Hints hash API

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

A new, experimental API has been added for accessing the internalstructure that Perl uses for %^H. See the functions beginning withcophh_ in perlapi.

C interface to caller()

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

Custom per-subroutine check hooks

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

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

Improved support for custom OPs

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

xop_class is one of the OA_*OP constants. It allows B and otherintrospection mechanisms to work with custom opsthat aren't BASEOPs. xop_peep is a pointer toa function that will be called for ops of thistype from Perl_rpeep.

See Custom Operators in perlguts and Custom Operators in perlapi for moredetail.

The old PL_custom_op_names/PL_custom_op_descs interface is stillsupported but discouraged.

Scope hooks

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

The recursive part of the peephole optimizer is now hookable

In addition to PL_peepp, for hooking into the toplevel peephole optimizer, aPL_rpeepp is now available to hook into the optimizer recursing intoside-chains of the optree.

New non-magical variants of existing functions

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

  sv_2bool_flags
   SvTRUE_nomg
   sv_2nv_flags
   SvNV_nomg
   sv_cmp_flags
   sv_cmp_locale_flags
   sv_eq_flags
   sv_collxfrm_flags

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

pv/pvs/sv versions of existing functions

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

List op-building functions

List op-building functions have been added to theAPI. See op_append_elem,op_append_list, andop_prepend_elem in perlapi.

`LINKLIST`

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

Localisation functions

The save_freeop, save_op, save_pushi32ptr and save_pushptrptrfunctions have been added to the API.

Stash names

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

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

New functions for finding and removing magic

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

`find_rundefsv`

This function returns the SV representing $_, whether it's lexicalor dynamic.

`Perl_croak_no_modify`

Perl_croak_no_modify() is short-hand forPerl_croak("%s", PL_no_modify).

`PERL_STATIC_INLINE` define

The PERL_STATIC_INLINE define has been added to provide the best-guessincantation to use for static inline functions, if the C compiler supportsC99-style static inline. If it doesn't, it'll give a plain static.

HAS_STATIC_INLINE can be used to check if the compiler actually supportsinline functions.

New `pv_escape` option for hexadecimal escapes

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

`lex_start`

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

op_scope() and op_lvalue()

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

C API Changes

`PERL_POLLUTE` has been removed

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

 perl Makefile.PL POLLUTE=1

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

Check API compatibility when loading XS modules

When Perl's API changes in incompatible ways (which usually happens betweenmajor releases), XS modules compiled for previous versions of Perl will nolonger work. They need to be recompiled against the new Perl.

The XS_APIVERSION_BOOTCHECK macro has been added to ensure that modulesare recompiled and to prevent users from accidentally loading modulescompiled for old perls into newer perls. That macro, which is called whenloading every newly compiled extension, compares the API version of therunning perl with the version a module has been compiled for and raises anexception if they don't match.

Perl_fetch_cop_label

The first argument of the C API function Perl_fetch_cop_label has changedfrom struct refcounted_he * to COP *, to insulate the user fromimplementation details.

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

GvCV() and GvGP() are no longer lvalues

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

This allows a future commit to eliminate some backref magic between GVand CVs, which will require complete control over assignment to thegp_cv slot.

CvGV() is no longer an lvalue

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

CvSTASH() is no longer an lvalue

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

Calling conventions for `newFOROP` and `newWHILEOP`

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

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

Flags passed to `uvuni_to_utf8_flags` and `utf8n_to_uvuni`

Some of the flags parameters to uvuni_to_utf8_flags() andutf8n_to_uvuni() have changed. This is a result of Perl's now allowinginternal storage and manipulation of code points that are problematicin some situations. Hence, the default actions for these functions hasbeen complemented to allow these code points. The new flags aredocumented in perlapi. Code that requires the problematic codepoints to be rejected needs to change to use the new flags. Some flagnames are retained for backward source compatibility, though they donothing, as they are now the default. However the flagsUNICODE_ALLOW_FDD0, UNICODE_ALLOW_FFFF, UNICODE_ILLEGAL, andUNICODE_IS_ILLEGAL have been removed, as they stem from afundamentally broken model of how the Unicode non-character code pointsshould be handled, which is now described inNon-character code points in perlunicode. See also the Unicode sectionunder Selected Bug Fixes.

Deprecated C APIs

Perl_ptr_table_clear
Perl_ptr_table_clear is no longer part of Perl's public API. Calling itnow generates a deprecation warning, and it will be removed in a futurerelease.
sv_compile_2op
The sv_compile_2op() API function is now deprecated. Searches suggestthat nothing on CPAN is using it, so this should have zero impact.
It attempted to provide an API to compile code down to an optree, but failedto bind correctly to lexicals in the enclosing scope. It's not possible tofix this problem within the constraints of its parameters and return value.
find_rundefsvoffset
The find_rundefsvoffset function has been deprecated. It appeared thatits design was insufficient for reliably getting the lexical $_ atrun-time.
Use the new find_rundefsv function or the UNDERBAR macroinstead. They directly return the right SVrepresenting $_, whether it'slexical or dynamic.
CALL_FPTR and CPERLscope
Those are left from an old implementation of MULTIPLICITY using C++ objects,which was removed in Perl 5.8. Nowadays these macros do exactly nothing, sothey shouldn't be used anymore.
For compatibility, they are still defined for external XS code. Onlyextensions defining PERL_CORE must be updated now.

Other Internal Changes

Stack unwinding

The protocol for unwinding the C stack at the last stage of a diehas changed how it identifies the target stack frame. This now usesa separate variable PL_restartjmpenv, where previously it relied onthe blk_eval.cur_top_env pointer in the eval context frame thathas nominally just been discarded. This change means that code runningduring various stages of Perl-level unwinding no longer needs to takecare to avoid destroying the ghost frame.

Scope stack entries

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

Memory allocation for pointer tables

Memory allocation for pointer tables has been changed. PreviouslyPerl_ptr_table_store allocated memory from the same arena system asSV bodies and HEs, with freed memory remaining bound to those arenasuntil interpreter exit. Now it allocates memory from arenas private to thespecific pointer table, and that memory is returned to the system whenPerl_ptr_table_free is called. Additionally, allocation and release areboth less CPU intensive.

`UNDERBAR`

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

String comparison routines renamed

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

`chop` and `chomp` implementations merged

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

Selected Bug Fixes

I/O

Perl no longer produces this warning:

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

Opening a glob reference via open($fh, ">", \*glob) no longercauses the glob to be corrupted when the filehandle is printed to. This wouldcause Perl to crash whenever the glob's contents were accessed[perl #77492].
PerlIO no longer crashes when called recursively, such as from a signalhandler. Now it just leaks memory [perl #75556].
Most I/O functions were not warning for unopened handles unless the"closed" and "unopened" warnings categories were both enabled. Now onlyuse warnings 'unopened' is necessary to trigger these warnings, ashad always been the intention.
There have been several fixes to PerlIO layers:
When binmode(FH, ":crlf") pushes the :crlf layer on top of the stack,it no longer enables crlf layers lower in the stack so as to avoidunexpected results [perl #38456].
Opening a file in :raw mode now does what it advertises to do (firstopen the file, then binmode it), instead of simply leaving off the toplayer [perl #80764].
The three layers :pop, :utf8, and :bytes didn't allow stacking whenopening a file. For examplethis:
```
 open(FH, ">:pop:perlio", "some.file") or die $!;
 
```
would throw an "Invalid argument" error. This has been fixed in thisrelease [perl #82484].

Regular Expression Bug Fixes

The regular expression engine no longer loops when matching"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i and similar expressions[perl #72998] (5.12.1).
The trie runtime code should no longer allocate massive amounts of memory,fixing #74484.
Syntax errors in (?{...}) blocks no longer cause panic messages[perl #2353].
A pattern like (?:(o){2})? no longer causes a "panic" error[perl #39233].
A fatal error in regular expressions containing (.*?) when processingUTF-8 data has been fixed [perl #75680] (5.12.2).
An erroneous regular expression engine optimisation that caused regex verbs like*COMMIT sometimes to be ignored has been removed.
The regular expression bracketed character class [\8\9] was effectively thesame as [89\000], incorrectly matching a NULL character. It also gaveincorrect warnings that the 8 and 9 were ignored. Now [\8\9] is thesame as [89] and gives legitimate warnings that \8 and \9 areunrecognized escape sequences, passed-through.
A regular expression match in the right-hand side of a global substitution(s///g) that is in the same scope will no longer cause match variablesto have the wrong values on subsequent iterations. This can happen when anarray or hash subscript is interpolated in the right-hand side, as ins|(.)|@a{ print($1), /./ }|g [perl #19078].
Several cases in which characters in the Latin-1 non-ASCII range (0x80 to0xFF) used not to match themselves, or used to match both a character classand its complement, have been fixed. For instance, U+00E2 could match both\w and \W [perl #78464] [perl #18281] [perl #60156].
Matching a Unicode character against an alternation containing charactersthat happened to match continuation bytes in the former's UTF8representation (like qq{\x{30ab}} =~ /\xab|\xa9/) would cause erroneouswarnings [perl #70998].
The trie optimisation was not taking empty groups into account, preventing"foo" from matching /\A(?:(?:)foo|bar|zot)\z/ [perl #78356].
A pattern containing a + inside a lookahead would sometimes cause anincorrect match failure in a global match (for example, /(?=(\S+))/g)[perl #68564].
A regular expression optimisation would sometimes cause a match with a{n,m} quantifier to fail when it should have matched [perl #79152].
Case-insensitive matching in regular expressions compiled underuse locale now works much more sanely when the pattern or targetstring is internally encoded in UTF8. Previously, under theseconditions the localeness was completely lost. Now, code pointsabove 255 are treated as Unicode, but code points between 0 and 255are treated using the current locale rules, regardless of whetherthe pattern or the string is encoded in UTF8. The few case-insensitivematches that cross the 255/256 boundary are not allowed. Forexample, 0xFF does not caselessly match the character at 0x178,LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be LATINSMALL LETTER Y in the current locale, and Perl has no way of knowingif that character even exists in the locale, much less what codepoint it is.
The (?|...) regular expression construct no longer crashes if the finalbranch has more sets of capturing parentheses than any other branch. Thiswas fixed in Perl 5.10.1 for the case of a single branch, but that fix didnot take multiple branches into account [perl #84746].
A bug has been fixed in the implementation of {...} quantifiers inregular expressions that prevented the code block in/((\w+)(?{ print $2 })){2}/ from seeing the $2 sometimes[perl #84294].

Syntax/Parsing Bugs

when (scalar) {...} no longer crashes, but produces a syntax error[perl #74114] (5.12.1).
A label right before a string eval (foo: eval $string) no longer causesthe label to be associated also with the first statement inside the eval[perl #74290] (5.12.1).
The no 5.13.2 form of no no longer tries to turn on features orpragmata (like strict) [perl #70075] (5.12.2).
BEGIN {require 5.12.0} now behaves as documented, rather than behavingidentically to use 5.12.0. Previously, require in a BEGIN blockwas erroneously executing the use feature ':5.12.0' anduse strict behaviour, which only use was documented toprovide [perl #69050].
A regression introduced in Perl 5.12.0, makingmy $x = 3; $x = length(undef) result in $x set to 3 has beenfixed. $x will now be undef [perl #85508] (5.12.2).
When strict "refs" mode is off, %{...} in rvalue context returnsundef if its argument is undefined. An optimisation introduced in Perl5.12.0 to make keys %{...} faster when used as a boolean did not takethis into account, causing keys %{+undef} (and keys %$foo when$foo is undefined) to be an error, which it should be so in strictmode only [perl #81750].
Constant-folding used to cause
```
  $text =~ ( 1 ? /phoo/ : /bear/)
 
```
to turn into
```
  $text =~ /phoo/
 
```
at compile time. Now it correctly matches against $_ [perl #20444].
Parsing Perl code (either with string eval or by loading modules) fromwithin a UNITCHECK block no longer causes the interpreter to crash[perl #70614].
String evals no longer fail after 2 billion scopes have beencompiled [perl #83364].
The parser no longer hangs when encountering certain Unicode characters,such as U+387 [perl #74022].
Defining a constant with the same name as one of Perl's special blocks(like INIT) stopped working in 5.12.0, but has now been fixed[perl #78634].
A reference to a literal value used as a hash key ($hash{\"foo"}) usedto be stringified, even if the hash was tied [perl #79178].
A closure containing an if statement followed by a constant or variableis no longer treated as a constant [perl #63540].
state can now be used with attributes. Itused to mean the same thing asmy if any attributes were present [perl #68658].
Expressions like @$a > 3 no longer cause $a to be mentioned inthe "Use of uninitialized value in numeric gt" warning when $a isundefined (since it is not part of the > expression, but the operandof the @) [perl #72090].
Accessing an element of a package array with a hard-coded number (asopposed to an arbitrary expression) would crash if the array did not exist.Usually the array would be autovivified during compilation, but typeglobmanipulation could remove it, as in these two cases which used to crash:
```
  *d = *a;  print $d[0];
   undef *d; print $d[0];
 
```
The -C command-line option, when used on the shebang line, can now befollowed by other options [perl #72434].
The B module was returning B::OPs instead of B::LOGOPs forentertry [perl #80622]. This was due to a bug in the Perl core,not in B itself.

Stashes, Globs and Method Lookup

Perl 5.10.0 introduced a new internal mechanism for caching MROs (methodresolution orders, or lists of parent classes; aka "isa" caches) to makemethod lookup faster (so @ISA arrays would not have to be searchedrepeatedly). Unfortunately, this brought with it quite a few bugs. Almostall of these have been fixed now, along with a few MRO-related bugs thatexisted before 5.10.0:

The following used to have erratic effects on method resolution, becausethe "isa" caches were not reset or otherwise ended up listing the wrongclasses. These have been fixed.
- Aliasing packages by assigning to globs [perl #77358]
- Deleting packages by deleting their containing stash elements
- Undefining the glob containing a package (undef *Foo::)
- Undefining an ISA glob (undef *Foo::ISA)
- Deleting an ISA stash element (delete $Foo::{ISA})
- Sharing @ISA arrays between classes (via *Foo::ISA = \@Bar::ISA or*Foo::ISA = *Bar::ISA) [perl #77238]
undef *Foo::ISA would even stop a new @Foo::ISA array from updatingcaches.
Typeglob assignments would crash if the glob's stash no longer existed, solong as the glob assigned to were named ISA or the glob on either side ofthe assignment contained a subroutine.
PL_isarev, which is accessible to Perl via mro::get_isarev is nowupdated properly when packages are deleted or removed from the @ISA ofother classes. This allows many packages to be created and deleted withoutcausing a memory leak [perl #75176].

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

Some work has been done on the internal pointers that link between symboltables (stashes), typeglobs, and subroutines. This has the effect thatvarious edge cases related to deleting stashes or stash entries (for example,<%FOO:: = ()>), and complex typeglob or code-reference aliasing, will nolonger crash the interpreter.
Assigning a reference to a glob copy now assigns to a glob slot instead ofoverwriting the glob with a scalar [perl #1804] [perl #77508].
A bug when replacing the glob of a loop variable within the loop has been fixed[perl #21469]. Thismeans the following code will no longer crash:
```
 for $x (...) {
  *x = *y;
  }
 
```
Assigning a glob to a PVLV used to convert it to a plain string. Now itworks correctly, and a PVLV can hold a glob. This would happen when anonexistent hash or array element was passed to a subroutine:
```
  sub { $_[0] = *foo }->($hash{key});
   # $_[0] would have been the string "*main::foo"
 
```
It also happened when a glob was assigned to, or returned from, an elementof a tied array or hash [perl #36051].
When trying to report Use of uninitialized value $Foo::BAR, crashes couldoccur if the glob holding the global variable in question had been detachedfrom its original stash by, for example, delete $::{"Foo::"}. This hasbeen fixed by disabling the reporting of variable names in thosecases.
During the restoration of a localised typeglob on scope exit, anydestructors called as a result would be able to see the typeglob in aninconsistent state, containing freed entries, which could result in acrash. This would affect code like this:
```
  local *@;
   eval { die bless [] }; # puts an object in $@
   sub DESTROY {
  local $@; # boom
   }
 
```
Now the glob entries are cleared before any destructors are called. Thisalso means that destructors can vivify entries in the glob. So Perl triesagain and, if the entries are re-created too many times, dies with a"panic: gp_free ..." error message.
If a typeglob is freed while a subroutine attached to it is stillreferenced elsewhere, the subroutine is renamed to __ANON__ in the samepackage, unless the package has been undefined, in which case the __ANON__package is used. This could cause packages to be sometimes autovivified,such as if the package had been deleted. Now this no longer occurs.The __ANON__ package is also now used when the original package isno longer attached to the symbol table. This avoids memory leaks in somecases [perl #87664].
Subroutines and package variables inside a package whose name ends with:: can now be accessed with a fully qualified name.

Unicode

What has become known as "the Unicode Bug" is almost completely resolved inthis release. Under use feature 'unicode_strings' (which isautomatically selected by use 5.012 and above), the internalstorage format of a string no longer affects the external semantics.[perl #58182].
There are two known exceptions:
1
The now-deprecated, user-defined case-changingfunctions require utf8-encoded strings to operate. The CPAN moduleUnicode::Casing has been written to replace this feature without itsdrawbacks, and the feature is scheduled to be removed in 5.16.
2
quotemeta() (and its in-line equivalent \Q) can also give differentresults depending on whether a string is encoded in UTF-8. SeeThe Unicode Bug in perlunicode.
Handling of Unicode non-character code points has changed.Previously they were mostly considered illegal, except that in someplace only one of the 66 of them was known. The Unicode Standardconsiders them all legal, but forbids their "open interchange".This is part of the change to allow internal use of any codepoint (see Core Enhancements). Together, these changes resolve[perl #38722], [perl #51918], [perl #51936], and [perl #63446].
Case-insensitive "/i" regular expression matching of Unicodecharacters that match multiple characters now works much more asintended. For example
```
 "\N{LATIN SMALL LIGATURE FFI}" =~ /ffi/ui
 
```
and
```
 "ffi" =~ /\N{LATIN SMALL LIGATURE FFI}/ui
 
```
are both true. Previously, there were many bugs with this feature.What hasn't been fixed are the places where the pattern contains themultiple characters, but the characters are split up by other things,such as in
```
 "\N{LATIN SMALL LIGATURE FFI}" =~ /(f)(f)i/ui
 
```
or
```
 "\N{LATIN SMALL LIGATURE FFI}" =~ /ffi*/ui
 
```
or
```
 "\N{LATIN SMALL LIGATURE FFI}" =~ /[a-f][f-m][g-z]/ui
 
```
None of these match.
Also, this matching doesn't fully conform to the current UnicodeStandard, which asks that the matching be made upon the NFD(Normalization Form Decomposed) of the text. However, as of thiswriting (April 2010), the Unicode Standard is currently in flux aboutwhat they will recommend doing with regard in such scenarios. It may bethat they will throw out the whole concept of multi-character matches.[perl #71736].
Naming a deprecated character in \N{NAME} no longer leaks memory.
We fixed a bug that could cause \N{NAME} constructs followed bya single "." to be parsed incorrectly [perl #74978] (5.12.1).
chop now correctly handles characters above "\x{7fffffff}"[perl #73246].
Passing to index an offset beyond the end of the string when the stringis encoded internally in UTF8 no longer causes panics [perl #75898].
warn() and die() now respect utf8-encoded scalars [perl #45549].
Sometimes the UTF8 length cache would not be reset on a valuereturned by substr, causing length(substr($uni_string, ...)) to givewrong answers. With ${^UTF8CACHE} set to -1, it would also producea "panic" error message [perl #77692].

Ties, Overloading and Other Magic

Overloading now works properly in conjunction with tiedvariables. What formerly happened was that most ops checked theirarguments for overloading before checking for magic, so for examplean overloaded object returned by a tied array access would usually betreated as not overloaded [RT #57012].
Various instances of magic (like tie methods) being called on tied variablestoo many or too few times have been fixed:
- $tied->() did not always call FETCH [perl #8438].
- Filetest operators and y/// and tr/// were calling FETCH toomany times.
- The = operator used to ignore magic on its right-hand side if thescalar happened to hold a typeglob (if a typeglob was the last thingreturned from or assigned to a tied scalar) [perl #77498].
- Dereference operators used to ignore magic if the argument was areference already (such as from a previous FETCH) [perl #72144].
- splice now calls set-magic (so changes madeby splice @ISA are respected by method calls) [perl #78400].
- In-memory files created by open($fh, ">", \$buffer) were not callingFETCH/STORE at all [perl #43789] (5.12.2).
- utf8::is_utf8() now respects get-magic (like $1) (5.12.1).
Non-commutative binary operators used to swap their operands if the sametied scalar was used for both operands and returned a different value foreach FETCH. For instance, if $t returned 2 the first time and 3 thesecond, then $t/$t would evaluate to 1.5. This has been fixed[perl #87708].
String eval now detects taintedness of overloaded or tiedarguments [perl #75716].
String eval and regular expression matches against objects with stringoverloading no longer cause memory corruption or crashes [perl #77084].
readline EXPR now honors <> overloading on tiedarguments.
<expr> always respects overloading now if the expression isoverloaded.
Because "<> as glob" was parsed differently from"<> as filehandle" from 5.6 onwards, something like <$foo[0]> didnot handle overloading, even if $foo[0] was an overloaded object. Thiswas contrary to the documentation for overload, and meant that <>could not be used as a general overloaded iterator operator.
The fallback behaviour of overloading on binary operators was asymmetric[perl #71286].
Magic applied to variables in the main package no longer affects other packages.See Magic variables outside the main package above [perl #76138].
Sometimes magic (ties, taintedness, etc.) attached to variables could causean object to last longer than it should, or cause a crash if a tiedvariable were freed from within a tie method. These have been fixed[perl #81230].
DESTROY methods of objects implementing ties are no longer able to crash byaccessing the tied variable through a weak reference [perl #86328].
Fixed a regression of kill() when a match variable is used for theprocess ID to kill [perl #75812].
$AUTOLOAD used to remain tainted forever if it ever became tainted. Nowit is correctly untainted if an autoloaded method is called and the methodname was not tainted.
sprintf now dies when passed a tainted scalar for the format. It didalready die for arbitrary expressions, but not for simple scalars[perl #82250].
lc, uc, lcfirst, and ucfirst no longer return untainted stringswhen the argument is tainted. This has been broken since perl 5.8.9[perl #87336].

The Debugger

The Perl debugger now also works in taint mode [perl #76872].
Subroutine redefinition works once more in the debugger [perl #48332].
When -d is used on the shebang (#!) line, the debugger now has accessto the lines of the main program. In the past, this sometimes worked andsometimes did not, depending on the order in which things happened to bearranged in memory [perl #71806].
A possible memory leak when using caller EXPR to set@DB::args has been fixed (5.12.2).
Perl no longer stomps on $DB::single, $DB::trace, and $DB::signal if these variables already have values when $^P is assigned to [perl #72422].
#line directives in string evals were not properly updating the arraysof lines of code (@{"_< ..."}) that the debugger (or any debugging orprofiling module) uses. In threaded builds, they were not being updated atall. In non-threaded builds, the line number was ignored, so any change tothe existing line number would cause the lines to be misnumbered[perl #79442].

Threads

Perl no longer accidentally clones lexicals in scope within active stackframes in the parent when creating a child thread [perl #73086].
Several memory leaks in cloning and freeing threaded Perl interpreters have beenfixed [perl #77352].
Creating a new thread when directory handles were open used to cause acrash, because the handles were not cloned, but simply passed to the newthread, resulting in a double free.
Now directory handles are cloned properly on Windowsand on systems that have a fchdir function. On othersystems, new threads simply do not inherit directoryhandles from their parent threads [perl #75154].
The typeglob *,, which holds the scalar variable $, (output fieldseparator), had the wrong reference count in child threads.
[perl #78494] When pipes are shared between threads, the close function(and any implicit close, such as on thread exit) no longer blocks.
Perl now does a timely cleanup of SVs that are cloned into a newthread but then discovered to be orphaned (that is, their ownersare not cloned). This eliminates several "scalars leaked"warnings when joining threads.

Scoping and Subroutines

Lvalue subroutines are again able to return copy-on-write scalars. Thishad been broken since version 5.10.0 [perl #75656] (5.12.3).
require no longer causes caller to return the wrong file name forthe scope that called require and other scopes higher up that had thesame file name [perl #68712].
sort with a ($$)-prototyped comparison routine used to cause the valueof @_ to leak out of the sort. Taking a reference to @_ within thesorting routine could cause a crash [perl #72334].
Match variables (like $1) no longer persist between calls to a sortsubroutine [perl #76026].
Iterating with foreach over an array returned by an lvalue sub now works[perl #23790].
$@ is now localised during calls to binmode to prevent action at adistance [perl #78844].
Calling a closure prototype (what is passed to an attribute handler for aclosure) now results in a "Closure prototype called" error message insteadof a crash [perl #68560].
Mentioning a read-only lexical variable from the enclosing scope in astring eval no longer causes the variable to become writable[perl #19135].

Signals

Within signal handlers, $! is now implicitly localized.
CHLD signals are no longer unblocked after a signal handler is called ifthey were blocked before by POSIX::sigprocmask [perl #82040].
A signal handler called within a signal handler could cause leaks ordouble-frees. Now fixed [perl #76248].

Miscellaneous Memory Leaks

Several memory leaks when loading XS modules were fixed (5.12.2).
substr EXPR,OFFSET,LENGTH,REPLACEMENT,index STR,SUBSTR,POSITION, keys HASH,and vec EXPR,OFFSET,BITS could, when used in combinationwith lvalues, result in leaking the scalar value they operate on, and cause itsdestruction to happen too late. This has now been fixed.
The postincrement and postdecrement operators, ++ and --, used to causeleaks when used on references. This has now been fixed.
Nested map and grep blocks no longer leak memory when processinglarge lists [perl #48004].
use VERSION and no VERSION no longer leak memory [perl #78436][perl #69050].
.= followed by <> or readline would leak memory if $/contained characters beyond the octet range and the scalar assigned tohappened to be encoded as UTF8 internally [perl #72246].
eval 'BEGIN{die}' no longer leaks memory on non-threaded builds.

Memory Corruption and Crashes

glob() no longer crashes when %File::Glob:: is empty andCORE::GLOBAL::glob isn't present [perl #75464] (5.12.2).
readline() has been fixed when interrupted by signals so it no longerreturns the "same thing" as before or random memory.
When assigning a list with duplicated keys to a hash, the assignment used toreturn garbage and/or freed values:
```
 @a = %h = (list with some duplicate keys);
 
```
This has now been fixed [perl #31865].
The mechanism for freeing objects in globs used to leave danglingpointers to freed SVs, meaning Perl users could see corrupted stateduring destruction.
Perl now frees only the affected slots of the GV, rather than freeingthe GV itself. This makes sure that there are no dangling refs orcorrupted state during destruction.
The interpreter no longer crashes when freeing deeply-nested arrays ofarrays. Hashes have not been fixed yet [perl #44225].
Concatenating long strings under use encoding no longer causes Perl tocrash [perl #78674].
Calling ->import on a class lacking an import method could corruptthe stack, resulting in strange behaviour. For instance,
```
  push @a, "foo", $b = bar->import;
 
```
would assign "foo" to $b [perl #63790].
The recv function could crash when called with the MSG_TRUNC flag[perl #75082].
formline no longer crashes when passed a tainted format picture. It alsotaints $^A now if its arguments are tainted [perl #79138].
A bug in how we process filetest operations could cause a segfault.Filetests don't always expect an op on the stack, so we now useTOPs only if we're sure that we're not stating the _ filehandle.This is indicated by OPf_KIDS (as checked in ck_ftst) [perl #74542](5.12.1).
unpack() now handles scalar context correctly for %32H and %32u,fixing a potential crash. split() would crash because the third itemon the stack wasn't the regular expression it expected. unpack("%2H",...) would return both the unpacked result and the checksum on the stack,as would unpack("%2u", ...) [perl #73814] (5.12.2).

Fixes to Various Perl Operators

The &, |, and ^ bitwise operators no longer coerce read-only arguments[perl #20661].
Stringifying a scalar containing "-0.0" no longer has the effect of turningfalse into true [perl #45133].
Some numeric operators were converting integers to floating point,resulting in loss of precision on 64-bit platforms [perl #77456].
sprintf() was ignoring locales when called with constant arguments[perl #78632].
Combining the vector (%v) flag and dynamic precision wouldcause sprintf to confuse the order of its arguments, making it treat the string as the precision and vice-versa [perl #83194].

Bugs Relating to the C API

The C-level lex_stuff_pvn function would sometimes cause a spurioussyntax error on the last line of the file if it lacked a final semicolon[perl #74006] (5.12.1).
The eval_sv and eval_pv C functions now set $@ correctly whenthere is a syntax error and no G_KEEPERR flag, and never set it if theG_KEEPERR flag is present [perl #3719].
The XS multicall API no longer causes subroutines to lose reference countsif called via the multicall interface from within those very subroutines.This affects modules like List::Util. Calling one of its functions with anactive subroutine as the first argument could cause a crash [perl #78070].
The SvPVbyte function available to XS modules now calls magic beforedowngrading the SV, to avoid warnings about wide characters [perl #72398].
The ref types in the typemap for XS bindings now support magical variables[perl #72684].
sv_catsv_flags no longer calls mg_get on its second argument (thesource string) if the flags passed to it do not include SV_GMAGIC. So itnow matches the documentation.
my_strftime no longer leaks memory. This fixes a memory leak inPOSIX::strftime [perl #73520].
XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS [perl #55049](5.12.1).
XS code using fputc() or fputs() on Windows could cause an errordue to their arguments being swapped [perl #72704] (5.12.1).
A possible segfault in the T_PTROBJ default typemap has been fixed(5.12.2).
A bug that could cause "Unknown error" messages whencall_sv(code, G_EVAL) is called from an XS destructor has been fixed(5.12.2).

Known Problems

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

List::Util::first misbehaves in the presence of a lexical $_(typically introduced by my $_ or implicitly by given). The variablethat gets set for each iteration is the package variable $_, not thelexical $_.
A similar issue may occur in other modules that provide functions whichtake a block as their first argument, like
```
 foo { ... $_ ...} list
 
```
See also: http://rt.perl.org/rt3/Public/Bug/Display.html?id=67694
readline() returns an empty string instead of a cached previous valuewhen it is interrupted by a signal
The changes in prototype handling break Switch. A patch has been sentupstream and will hopefully appear on CPAN soon.
The upgrade to ExtUtils-MakeMaker-6.57_05 has causedsome tests in the Module-Install distribution on CPAN tofail. (Specifically, 02_mymeta.t tests 5 and 21; 18_all_from.ttests 6 and 15; 19_authors.t tests 5, 13, 21, and 29; and20_authors_with_special_characters.t tests 6, 15, and 23 in version1.00 of that distribution now fail.)
On VMS, Time::HiRes tests will fail due to a bug in the CRTL'simplementation of setitimer: previous timer values would be clearedif a timer expired but not if the timer was reset before expiring. HPOpenVMS Engineering have corrected the problem and will release a patchin due course (Quix case # QXCM1001115136).
On VMS, there were a handful of Module::Build test failures we didn'tget to before the release; please watch CPAN for updates.

Errata

keys(), values(), and each() work on arrays

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

split() and `@_`

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

Obituary

Randy Kobes, creator of http://kobesearch.cpan.org/ andcontributor/maintainer to several core Perl toolchain modules, passedaway on September 18, 2010 after a battle with lung cancer. The communitywas richer for his involvement. He will be missed.

Acknowledgements

Perl 5.14.0 represents one year of development sincePerl 5.12.0 and contains nearly 550,000 lines of changes across nearly3,000 files from 150 authors and committers.

Perl continues to flourish into its third decade thanks to a vibrantcommunity of users and developers. The following people are known tohave contributed the improvements that became Perl 5.14.0:

Aaron Crane, Abhijit Menon-Sen, Abigail, Ævar Arnfjörð Bjarmason,Alastair Douglas, Alexander Alekseev, Alexander Hartmaier, AlexandrCiornii, Alex Davies, Alex Vandiver, Ali Polatel, Allen Smith, AndreasKönig, Andrew Rodland, Andy Armstrong, Andy Dougherty, AristotlePagaltzis, Arkturuz, Arvan, A. Sinan Unur, Ben Morrow, Bo Lindbergh,Boris Ratner, Brad Gilbert, Bram, brian d foy, Brian Phillips, CaseyWest, Charles Bailey, Chas. Owens, Chip Salzenberg, Chris 'BinGOs'Williams, chromatic, Craig A. Berry, Curtis Jewell, Dagfinn IlmariMannsåker, Dan Dascalescu, Dave Rolsky, David Caldwell, David Cantrell,David Golden, David Leadbeater, David Mitchell, David Wheeler, EricBrine, Father Chrysostomos, Fingle Nark, Florian Ragwitz, Frank Wiegand,Franz Fasching, Gene Sullivan, George Greer, Gerard Goossen, Gisle Aas,Goro Fuji, Grant McLean, gregor herrmann, H.Merijn Brand, Hongwen Qiu,Hugo van der Sanden, Ian Goodacre, James E Keenan, James Mastros, JanDubois, Jay Hannah, Jerry D. Hedden, Jesse Vincent, Jim Cromie, JirkaHruška, John Peacock, Joshua ben Jore, Joshua Pritikin, Karl Williamson,Kevin Ryde, kmx, Lars Dɪᴇᴄᴋᴏᴡ 迪拉斯, Larwan Berke, Leon Brocard, LeonTimmermans, Lubomir Rintel, Lukas Mai, Maik Hentsche, Marty Pauley,Marvin Humphrey, Matt Johnson, Matt S Trout, Max Maischein, MichaelBreen, Michael Fig, Michael G Schwern, Michael Parker, Michael Stevens,Michael Witten, Mike Kelly, Moritz Lenz, Nicholas Clark, Nick Cleaton,Nick Johnston, Nicolas Kaiser, Niko Tyni, Noirin Shirley, Nuno Carvalho,Paul Evans, Paul Green, Paul Johnson, Paul Marquess, Peter J. Holzer,Peter John Acklam, Peter Martini, Philippe Bruhat (BooK), Piotr Fusik,Rafael Garcia-Suarez, Rainer Tammer, Reini Urban, Renee Baecker, RicardoSignes, Richard Möhn, Richard Soderberg, Rob Hoelz, Robin Barker, RuslanZakirov, Salvador Fandiño, Salvador Ortiz Garcia, Shlomi Fish, SinanUnur, Sisyphus, Slaven Rezic, Steffen Müller, Steve Hay, StevenSchubiger, Steve Peters, Sullivan Beck, Tatsuhiko Miyagawa, Tim Bunce,Todd Rinaldo, Tom Christiansen, Tom Hukins, Tony Cook, Tye McQueen,Vadim Konovalov, Vernon Lyon, Vincent Pit, Walt Mankowski, WolframHumann, Yves Orton, Zefram, and Zsbán Ambrus.

This is woefully incomplete as it's automatically generated from versioncontrol history. In particular, it doesn't include the names of the(very much appreciated) contributors who reported issues in previousversions of Perl that helped make Perl 5.14.0 better. For a more completelist of all of Perl's historical contributors, please see the AUTHORSfile in the Perl 5.14.0 distribution.

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

Reporting Bugs

If you find what you think is a bug, you might check the articlesrecently posted to the comp.lang.perl.misc newsgroup and the Perlbug database at http://rt.perl.org/perlbug/ . There may also beinformation at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbugprogram included with your release. Be sure to trim your bug downto a tiny but sufficient test case. Your bug report, along with theoutput of perl -V, will be sent off to [email protected] to beanalysed by the Perl porting team.

If the bug you are reporting has security implications, which make itinappropriate to send to a publicly archived mailing list, then please sendit to [email protected]. This points to a closed subscriptionunarchived mailing list, which includes all the core committers, who are ableto help assess the impact of issues, figure out a resolution, and helpco-ordinate the release of patches to mitigate or fix the problem across allplatforms on which Perl is supported. Please use this address forsecurity issues in the Perl core only, not for modules independentlydistributed on CPAN.

What is new for perl v5.14.0

Daftar Isi

NAME

DESCRIPTION

Notice

Core Enhancements

Unicode

Unicode Version 6.0 is now supported (mostly)

Full functionality for use feature 'unicode_strings'

\N{NAME} and charnames enhancements

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

Any unsigned value can be encoded as a character

Unicode database files not installed

Regular Expressions

(?^...) construct signifies default modifiers

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

Non-destructive substitution

Re-entrant regular expression engine

use re '/flags'

\o{...} for octals

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

Regular expression debugging output improvement

Return value of delete $+{...}

Syntactical Enhancements

Array and hash container functions accept references

Single term prototype

package block syntax

Statement labels can appear in more places

Stacked labels

Uppercase X/B allowed in hexadecimal/binary literals

Overridable tie functions

Exception Handling

Other Enhancements

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

srand() now returns the seed

printf-like functions understand post-1980 size modifiers

New global variable ${^GLOBAL_PHASE}

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

Filehandle method calls load IO::File on demand

Improved IPv6 support

DTrace probes now include package name

New C APIs

Security

User-defined regular expression properties

Incompatible Changes

Regular Expressions and String Escapes

Inverted bracketed character classes and multi-character folds

\400-\777

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

\p{} implies Unicode semantics

Regular expressions retain their localeness when interpolated

Stringification of regexes has changed

Run-time code blocks in regular expressions inherit pragmata

Stashes and Package Variables

Localised tied hashes and arrays are no longed tied

Stashes are now always defined

Clearing stashes

Dereferencing typeglobs

Magic variables outside the main package

local($_) strips all magic from $_

Parsing of package and variable names

Changes to Syntax or to Perl Operators

given return values

Change in parsing of certain prototypes

Smart-matching against array slices

Negation treats strings differently from before

Negative zero

:= is now a syntax error

Change in the parsing of identifiers

Threads and Processes

Directory handles not copied to threads

close on shared pipes

fork() emulation will not wait for signalled children

Configuration

Naming fixes in Policy_sh.SH may invalidate Policy.sh

Perl source code is read in text mode on Windows

Deprecations

Omitting a space between a regular expression and subsequent word

\cX

"\b{" and "\B{"

Full functionality for `use feature 'unicode_strings'`

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

`(?^...)` construct signifies default modifiers

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

`use re '/flags'`

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

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

`package` block syntax

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

New global variable `${^GLOBAL_PHASE}`

`-d:-foo` calls `Devel::foo::unimport`

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

`given` return values

`:=` is now a syntax error

`close` on shared pipes

`\cX`

`"\b{"` and `"\B{"`

List assignment to `$[`

`\N{BELL}`

`?PATTERN?`

Eliminate `PL_*` accessor functions under ithreads

`@_` uses less memory

`%+` and `%-` use less memory

Explanation of `\xHH` and `\oOOO` escapes

`SvTRUE` macro

`use locale` and formats