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            <h1>perl5120delta</h1>


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<ul><li><a href="#NAME">NAME</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#Core-Enhancements">Core Enhancements</a><ul><li><a href="#New-package-NAME-VERSION-syntax">New package NAME VERSION syntax</a><li><a href="#The-...-operator">The ... operator</a><li><a href="#Implicit-strictures">Implicit strictures</a><li><a href="#Unicode-improvements">Unicode improvements</a><li><a href="#Y2038-compliance">Y2038 compliance</a><li><a href="#qr-overloading">qr overloading</a><li><a href="#Pluggable-keywords">Pluggable keywords</a><li><a href="#APIs-for-more-internals">APIs for more internals</a><li><a href="#Overridable-function-lookup">Overridable function lookup</a><li><a href="#A-proper-interface-for-pluggable-Method-Resolution-Orders">A proper interface for pluggable Method Resolution Orders</a><li><a href="#%5cN-experimental-regex-escape">\N experimental regex escape</a><li><a href="#DTrace-support">DTrace support</a><li><a href="#Support-for-configure_requires-in-CPAN-module-metadata">Support for configure_requires in CPAN module metadata</a><li><a href="#each%2c-keys%2c-values-are-now-more-flexible">each, keys, values are now more flexible</a><li><a href="#when-as-a-statement-modifier">when as a statement modifier</a><li><a href="#%24%2c-flexibility">$, flexibility</a><li><a href="#%2f%2f-in-when-clauses">// in when clauses</a><li><a href="#Enabling-warnings-from-your-shell-environment">Enabling warnings from your shell environment</a><li><a href="#delete-local">delete local</a><li><a href="#New-support-for-Abstract-namespace-sockets">New support for Abstract namespace sockets</a><li><a href="#32-bit-limit-on-substr-arguments-removed">32-bit limit on substr arguments removed</a></ul><li><a href="#Potentially-Incompatible-Changes">Potentially Incompatible Changes</a><ul><li><a href="#Deprecations-warn-by-default">Deprecations warn by default</a><li><a href="#Version-number-formats">Version number formats</a><li><a href="#%40INC-reorganization">@INC reorganization</a><li><a href="#REGEXPs-are-now-first-class">REGEXPs are now first class</a><li><a href="#Switch-statement-changes">Switch statement changes</a><li><a href="#Smart-match-changes">Smart match changes</a><li><a href="#Other-potentially-incompatible-changes">Other potentially incompatible changes</a></ul><li><a href="#Deprecations">Deprecations</a><li><a href="#Unicode-overhaul">Unicode overhaul</a><li><a href="#Modules-and-Pragmata">Modules and Pragmata</a><ul><li><a href="#New-Modules-and-Pragmata">New Modules and Pragmata</a><li><a href="#Updated-Pragmata">Updated Pragmata</a><li><a href="#Updated-Modules">Updated Modules</a><li><a href="#Removed-Modules-and-Pragmata">Removed Modules and Pragmata</a><li><a href="#Deprecated-Modules-and-Pragmata">Deprecated Modules and Pragmata</a></ul><li><a href="#Documentation">Documentation</a><ul><li><a href="#New-Documentation">New Documentation</a><li><a href="#Changes-to-Existing-Documentation">Changes to Existing Documentation</a></ul><li><a href="#Selected-Performance-Enhancements">Selected Performance Enhancements</a><li><a href="#Installation-and-Configuration-Improvements">Installation and Configuration Improvements</a><li><a href="#Internal-Changes">Internal Changes</a><li><a href="#Testing">Testing</a><ul><li><a href="#Testing-improvements">Testing improvements</a><li><a href="#New-Tests">New Tests</a></ul><li><a href="#New-or-Changed-Diagnostics">New or Changed Diagnostics</a><ul><li><a href="#New-Diagnostics">New Diagnostics</a><li><a href="#Changed-Diagnostics">Changed Diagnostics</a></ul><li><a href="#Utility-Changes">Utility Changes</a><li><a href="#Selected-Bug-Fixes">Selected Bug Fixes</a><li><a href="#Platform-Specific-Changes">Platform Specific Changes</a><ul><li><a href="#New-Platforms">New Platforms</a><li><a href="#Discontinued-Platforms">Discontinued Platforms</a><li><a href="#Updated-Platforms">Updated Platforms</a></ul><li><a href="#Known-Problems">Known Problems</a><li><a href="#Errata">Errata</a><li><a href="#Acknowledgements">Acknowledgements</a><li><a href="#Reporting-Bugs">Reporting Bugs</a><li><a href="#SEE-ALSO">SEE ALSO</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>perl5120delta - what is new for perl v5.12.0</p>
<a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p>This document describes differences between the 5.10.0 release and the
5.12.0 release.</p>
<p>Many of the bug fixes in 5.12.0 are already included in the 5.10.1
maintenance release.</p>
<p>You can see the list of those changes in the 5.10.1 release notes
(<a href="perl5101delta.html">perl5101delta</a>).</p>
<a name="Core-Enhancements"></a><h1>Core Enhancements</h1>
<a name="New-package-NAME-VERSION-syntax"></a><h2>New <code class="inline">package NAME VERSION</code> syntax</h2>
<p>This new syntax allows a module author to set the $VERSION of a namespace
when the namespace is declared with 'package'. It eliminates the need
for <code class="inline"><a class="l_k" href="functions/our.html">our</a> <span class="i">$VERSION</span> = ...</code>
 and similar constructs. E.g.</p>
<pre class="verbatim"><ol><li>      package Foo::Bar 1.23;</li><li>      # $Foo::Bar::VERSION == 1.23</li></ol></pre><p>There are several advantages to this:</p>
<ul>
<li>
<p><code class="inline"><span class="i">$VERSION</span></code>
 is parsed in exactly the same way as <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">NAME</span> <span class="w">VERSION</span></code>
</p>
</li>
<li>
<p><code class="inline"><span class="i">$VERSION</span></code>
 is set at compile time</p>
</li>
<li>
<p><code class="inline"><span class="i">$VERSION</span></code>
 is a version object that provides proper overloading of
comparison operators so comparing <code class="inline"><span class="i">$VERSION</span></code>
 to decimal (1.23) or
dotted-decimal (v1.2.3) version numbers works correctly.</p>
</li>
<li>
<p>Eliminates <code class="inline"><span class="i">$VERSION</span> = ...</code>
 and <code class="inline"><a class="l_k" href="functions/eval.html">eval</a> <span class="i">$VERSION</span></code>
 clutter</p>
</li>
<li>
<p>As it requires VERSION to be a numeric literal or v-string
literal, it can be statically parsed by toolchain modules
without <code class="inline"><a class="l_k" href="functions/eval.html">eval</a></code> the way MM-&gt;parse_version does for <code class="inline"><span class="i">$VERSION</span> = ...</code>
</p>
</li>
</ul>
<p>It does not break old code with only <code class="inline">package NAME</code>, but code that uses
<code class="inline">package NAME VERSION</code> will need to be restricted to perl 5.12.0 or newer
This is analogous to the change to <code class="inline"><a class="l_k" href="functions/open.html">open</a></code> from two-args to three-args.
Users requiring the latest Perl will benefit, and perhaps after several
years, it will become a standard practice.</p>
<p>However, <code class="inline">package NAME VERSION</code> requires a new, 'strict' version
number format. See <a href="#Version-number-formats">Version number formats</a> for details.</p>
<a name="The-...-operator"></a><h2>The <code class="inline">...</code>
 operator</h2>
<p>A new operator, <code class="inline">...</code>
, nicknamed the Yada Yada operator, has been added.
It is intended to mark placeholder code that is not yet implemented.
See <a href="perlop.html#Yada-Yada-Operator">Yada Yada Operator in perlop</a>.</p>
<a name="Implicit-strictures"></a><h2>Implicit strictures</h2>
<p>Using the <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">VERSION</span></code>
 syntax with a version number greater or equal
to 5.11.0 will lexically enable strictures just like <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">strict</span></code>

would do (in addition to enabling features.) The following:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="v">5.12.0</span><span class="sc">;</span></li></ol></pre><p>means:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">strict</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">feature</span> <span class="q">&#39;:5.12&#39;</span><span class="sc">;</span></li></ol></pre><a name="Unicode-improvements"></a><h2>Unicode improvements</h2>
<p>Perl 5.12 comes with Unicode 5.2, the latest version available to
us at the time of release.  This version of Unicode was released in
October 2009. See <a href="http://www.unicode.org/versions/Unicode5.2.0">http://www.unicode.org/versions/Unicode5.2.0</a> for
further details about what's changed in this version of the standard.
See <a href="perlunicode.html">perlunicode</a> for instructions on installing and using other versions
of Unicode.</p>
<p>Additionally, Perl's developers have significantly improved Perl's Unicode
implementation. For full details, see <a href="#Unicode-overhaul">Unicode overhaul</a> below.</p>
<a name="Y2038-compliance"></a><h2>Y2038 compliance</h2>
<p>Perl's core time-related functions are now Y2038 compliant. (It may not mean much to you, but your kids will love it!)</p>
<a name="qr-overloading"></a><h2>qr overloading</h2>
<p>It is now possible to overload the <code class="inline"><a class="l_k" href="functions/qr.html">qr//</a></code> operator, that is,
conversion to regexp, like it was already possible to overload
conversion to boolean, string or number of objects. It is invoked when
an object appears on the right hand side of the <code class="inline">=~</code>
 operator or when
it is interpolated into a regexp. See <a href="overload.html">overload</a>.</p>
<a name="Pluggable-keywords"></a><h2>Pluggable keywords</h2>
<p>Extension modules can now cleanly hook into the Perl parser to define
new kinds of keyword-headed expression and compound statement. The
syntax following the keyword is defined entirely by the extension. This
allows a completely non-Perl sublanguage to be parsed inline, with the
correct ops cleanly generated.</p>
<p>See <a href="perlapi.html#PL_keyword_plugin">PL_keyword_plugin in perlapi</a> for the mechanism. The Perl core
source distribution also includes a new module
<a href="http://search.cpan.org/perldoc/XS::APItest::KeywordRPN">XS::APItest::KeywordRPN</a>, which implements reverse Polish notation
arithmetic via pluggable keywords. This module is mainly used for test
purposes, and is not normally installed, but also serves as an example
of how to use the new mechanism.</p>
<p>Perl's developers consider this feature to be experimental. We may remove
it or change it in a backwards-incompatible way in Perl 5.14.</p>
<a name="APIs-for-more-internals"></a><h2>APIs for more internals</h2>
<p>The lowest layers of the lexer and parts of the pad system now have C
APIs available to XS extensions. These are necessary to support proper
use of pluggable keywords, but have other uses too. The new APIs are
experimental, and only cover a small proportion of what would be
necessary to take full advantage of the core's facilities in these
areas. It is intended that the Perl 5.13 development cycle will see the
addition of a full range of clean, supported interfaces.</p>
<p>Perl's developers consider this feature to be experimental. We may remove
it or change it in a backwards-incompatible way in Perl 5.14.</p>
<a name="Overridable-function-lookup"></a><h2>Overridable function lookup</h2>
<p>Where an extension module hooks the creation of rv2cv ops to modify the
subroutine lookup process, this now works correctly for bareword
subroutine calls. This means that prototypes on subroutines referenced
this way will be processed correctly. (Previously bareword subroutine
names were initially looked up, for parsing purposes, by an unhookable
mechanism, so extensions could only properly influence subroutine names
that appeared with an <code class="inline"><span class="i">&amp;</span></code>
 sigil.)</p>
<a name="A-proper-interface-for-pluggable-Method-Resolution-Orders"></a><h2>A proper interface for pluggable Method Resolution Orders</h2>
<p>As of Perl 5.12.0 there is a new interface for plugging and using method
resolution orders other than the default linear depth first search.
The C3 method resolution order added in 5.10.0 has been re-implemented as
a plugin, without changing its Perl-space interface. See <a href="perlmroapi.html">perlmroapi</a> for
more information.</p>
<a name="%5cN-experimental-regex-escape"></a><h2><code class="inline">\<span class="w">N</span></code>
 experimental regex escape</h2>
<p>Perl now supports <code class="inline">\<span class="w">N</span></code>
, a new regex escape which you can think of as
the inverse of <code class="inline">\<span class="w">n</span></code>
. It will match any character that is not a newline,
independently from the presence or absence of the single line match
modifier <code class="inline">/s</code>. It is not usable within a character class.  <code class="inline">\<span class="i">N</span><span class="s">{</span><span class="n">3</span><span class="s">}</span></code>

means to match 3 non-newlines; <code class="inline">\<span class="w">N</span><span class="s">{</span><span class="n">5</span><span class="cm">,</span><span class="s">}</span></code>
 means to match at least 5.
<code class="inline">\<span class="i">N</span><span class="s">{</span><span class="w">NAME</span><span class="s">}</span></code>
 still means the character or sequence named <code class="inline"><span class="w">NAME</span></code>
, but
<code class="inline"><span class="w">NAME</span></code>
 no longer can be things like <code class="inline"><span class="n">3</span></code>
, or <code class="inline"><span class="n">5</span><span class="cm">,</span></code>
.</p>
<p>This will break a <a href="charnames.html#CUSTOM-TRANSLATORS">custom charnames translator</a> which allows numbers for character names, as <code class="inline">\<span class="i">N</span><span class="s">{</span><span class="n">3</span><span class="s">}</span></code>
 will
now mean to match 3 non-newline characters, and not the character whose
name is <code class="inline"><span class="n">3</span></code>
. (No name defined by the Unicode standard is a number,
so only custom translators might be affected.)</p>
<p>Perl's developers are somewhat concerned about possible user confusion
with the existing <code class="inline">\<span class="i">N</span><span class="s">{</span>...<span class="s">}</span></code>
 construct which matches characters by their
Unicode name. Consequently, this feature is experimental. We may remove
it or change it in a backwards-incompatible way in Perl 5.14.</p>
<a name="DTrace-support"></a><h2>DTrace support</h2>
<p>Perl now has some support for DTrace. See "DTrace support" in <i>INSTALL</i>.</p>
<a name="Support-for-configure_requires-in-CPAN-module-metadata"></a><h2>Support for <code class="inline"><span class="w">configure_requires</span></code>
 in CPAN module metadata</h2>
<p>Both <code class="inline"><span class="w">CPAN</span></code>
 and <code class="inline"><span class="w">CPANPLUS</span></code>
 now support the <code class="inline"><span class="w">configure_requires</span></code>

keyword in the <i>META.yml</i> metadata file included in most recent CPAN
distributions.  This allows distribution authors to specify configuration
prerequisites that must be installed before running <i>Makefile.PL</i>
or <i>Build.PL</i>.</p>
<p>See the documentation for <code class="inline"><span class="w">ExtUtils::MakeMaker</span></code>
 or <code class="inline"><span class="w">Module::Build</span></code>
 for
more on how to specify <code class="inline"><span class="w">configure_requires</span></code>
 when creating a distribution
for CPAN.</p>
<a name="each%2c-keys%2c-values-are-now-more-flexible"></a><h2><code class="inline"><a class="l_k" href="functions/each.html">each</a></code>, <code class="inline"><a class="l_k" href="functions/keys.html">keys</a></code>, <code class="inline"><a class="l_k" href="functions/values.html">values</a></code> are now more flexible</h2>
<p>The <code class="inline"><a class="l_k" href="functions/each.html">each</a></code>, <code class="inline"><a class="l_k" href="functions/keys.html">keys</a></code>, <code class="inline"><a class="l_k" href="functions/values.html">values</a></code> function can now operate on arrays.</p>
<a name="when-as-a-statement-modifier"></a><h2><code class="inline">when</code>
 as a statement modifier</h2>
<p><code class="inline">when</code>
 is now allowed to be used as a statement modifier.</p>
<a name="%24%2c-flexibility"></a><h2><code class="inline"><span class="i">$,</span></code>
 flexibility</h2>
<p>The variable <code class="inline"><span class="i">$,</span></code>
 may now be tied.</p>
<a name="%2f%2f-in-when-clauses"></a><h2>// in when clauses</h2>
<p>// now behaves like || in when clauses</p>
<a name="Enabling-warnings-from-your-shell-environment"></a><h2>Enabling warnings from your shell environment</h2>
<p>You can now set <code class="inline">-W</code>
 from the <code class="inline"><span class="w">PERL5OPT</span></code>
 environment variable</p>
<a name="delete-local"></a><h2><code class="inline"><a class="l_k" href="functions/delete.html">delete</a> <a class="l_k" href="functions/local.html">local</a></code>
</h2>
<p><code class="inline"><a class="l_k" href="functions/delete.html">delete</a> <a class="l_k" href="functions/local.html">local</a></code>
 now allows you to locally delete a hash entry.</p>
<a name="New-support-for-Abstract-namespace-sockets"></a><h2>New support for Abstract namespace sockets</h2>
<p>Abstract namespace sockets are Linux-specific socket type that live in
AF_UNIX family, slightly abusing it to be able to use arbitrary
character arrays as addresses: They start with nul byte and are not
terminated by nul byte, but with the length passed to the socket()
system call.</p>
<a name="32-bit-limit-on-substr-arguments-removed"></a><h2>32-bit limit on substr arguments removed</h2>
<p>The 32-bit limit on <code class="inline"><a class="l_k" href="functions/substr.html">substr</a></code> arguments has now been removed. The full
range of the system's signed and unsigned integers is now available for
the <code class="inline"><a class="l_k" href="functions/pos.html">pos</a></code> and <code class="inline"><span class="w">len</span></code>
 arguments.</p>
<a name="Potentially-Incompatible-Changes"></a><h1>Potentially Incompatible Changes</h1>
<a name="Deprecations-warn-by-default"></a><h2>Deprecations warn by default</h2>
<p>Over the years, Perl's developers have deprecated a number of language
features for a variety of reasons.  Perl now defaults to issuing a
warning if a deprecated language feature is used. Many of the deprecations
Perl now warns you about have been deprecated for many years.  You can
find a list of what was deprecated in a given release of Perl in the
<code class="inline"><span class="w">perl5xxdelta</span>.<span class="w">pod</span></code>
 file for that release.</p>
<p>To disable this feature in a given lexical scope, you should use <code class="inline"><a class="l_k" href="functions/no.html">no</a>
<span class="w">warnings</span> <span class="q">&#39;deprecated&#39;</span><span class="sc">;</span></code>
 For information about which language features
are deprecated and explanations of various deprecation warnings, please
see <a href="perldiag.html">perldiag</a>. See <a href="#Deprecations">Deprecations</a> below for the list of features
and modules Perl's developers have deprecated as part of this release.</p>
<a name="Version-number-formats"></a><h2>Version number formats</h2>
<p>Acceptable version number formats have been formalized into "strict" and
"lax" rules. <code class="inline">package NAME VERSION</code> takes a strict version number.
<code class="inline"><span class="w">UNIVERSAL::VERSION</span></code>
 and the <a href="version.html">version</a> object constructors take lax
version numbers. Providing an invalid version will result in a fatal
error. The version argument in <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">NAME</span> <span class="w">VERSION</span></code>
 is first parsed as a
numeric literal or v-string and then passed to <code class="inline"><span class="w">UNIVERSAL::VERSION</span></code>

(and must then pass the "lax" format test).</p>
<p>These formats are documented fully in the <a href="version.html">version</a> module. To a first
approximation, a "strict" version number is a positive decimal number
(integer or decimal-fraction) without exponentiation or else a
dotted-decimal v-string with a leading 'v' character and at least three
components. A "lax" version number allows v-strings with fewer than
three components or without a leading 'v'. Under "lax" rules, both
decimal and dotted-decimal versions may have a trailing "alpha"
component separated by an underscore character after a fractional or
dotted-decimal component.</p>
<p>The <a href="version.html">version</a> module adds <code class="inline"><span class="w">version::is_strict</span></code>
 and <code class="inline"><span class="w">version::is_lax</span></code>

functions to check a scalar against these rules.</p>
<a name="%40INC-reorganization"></a><h2>@INC reorganization</h2>
<p>In <code class="inline"><span class="i">@INC</span></code>
, <code class="inline"><span class="w">ARCHLIB</span></code>
 and <code class="inline"><span class="w">PRIVLIB</span></code>
 now occur after the current
version's <code class="inline"><span class="w">site_perl</span></code>
 and <code class="inline"><span class="w">vendor_perl</span></code>
.  Modules installed into
<code class="inline"><span class="w">site_perl</span></code>
 and <code class="inline"><span class="w">vendor_perl</span></code>
 will now be loaded in preference to
those installed in <code class="inline"><span class="w">ARCHLIB</span></code>
 and <code class="inline"><span class="w">PRIVLIB</span></code>
.</p>
<a name="REGEXPs-are-now-first-class"></a><h2>REGEXPs are now first class</h2>
<p>Internally, Perl now treats compiled regular expressions (such as
those created with <code class="inline"><a class="l_k" href="functions/qr.html">qr//</a></code>) as first class entities. Perl modules which
serialize, deserialize or otherwise have deep interaction with Perl's
internal data structures need to be updated for this change.  Most
affected CPAN modules have already been updated as of this writing.</p>
<a name="Switch-statement-changes"></a><h2>Switch statement changes</h2>
<p>The <code class="inline">given</code>
/<code class="inline">when</code>
 switch statement handles complex statements better
than Perl 5.10.0 did (These enhancements are also available in
5.10.1 and subsequent 5.10 releases.) There are two new cases where
<code class="inline">when</code>
 now interprets its argument as a boolean, instead of an
expression to be used in a smart match:</p>
<ul>
<li><a name="flip-flop-operators"></a><b>flip-flop operators</b>
<p>The <code class="inline">..</code>
 and <code class="inline">...</code>
 flip-flop operators are now evaluated in boolean
context, following their usual semantics; see <a href="perlop.html#Range-Operators">Range Operators in perlop</a>.</p>
<p>Note that, as in perl 5.10.0, <code class="inline">when <span class="s">(</span><span class="n">1</span>..<span class="n">10</span><span class="s">)</span></code>
 will not work to test
whether a given value is an integer between 1 and 10; you should use
<code class="inline">when <span class="s">(</span><span class="s">[</span><span class="n">1</span>..<span class="n">10</span><span class="s">]</span><span class="s">)</span></code>
 instead (note the array reference).</p>
<p>However, contrary to 5.10.0, evaluating the flip-flop operators in
boolean context ensures it can now be useful in a <code class="inline">when<span class="s">(</span><span class="s">)</span></code>
, notably
for implementing bistable conditions, like in:</p>
<pre class="verbatim"><ol><li>    when <span class="s">(</span><span class="q">/^=begin/</span> .. <span class="q">/^=end/</span><span class="s">)</span> <span class="s">{</span></li><li>      <span class="c"># do something</span></li><li>    <span class="s">}</span></li></ol></pre></li>
<li><a name="defined-or-operator"></a><b>defined-or operator</b>
<p>A compound expression involving the defined-or operator, as in
<code class="inline">when (expr1 // expr2)</code>, will be treated as boolean if the first
expression is boolean. (This just extends the existing rule that applies
to the regular or operator, as in <code class="inline">when <span class="s">(</span><span class="w">expr1</span> || <span class="w">expr2</span><span class="s">)</span></code>
.)</p>
</li>
</ul>
<a name="Smart-match-changes"></a><h2>Smart match changes</h2>
<p>Since Perl 5.10.0, Perl's developers have made a number of changes to
the smart match operator. These, of course, also alter the behaviour
of the switch statements where smart matching is implicitly used.
These changes were also made for the 5.10.1 release, and will remain in
subsequent 5.10 releases.</p>
<a name="Changes-to-type-based-dispatch"></a><h3>Changes to type-based dispatch</h3>
<p>The smart match operator <code class="inline">~~</code>
 is no longer commutative. The behaviour of
a smart match now depends primarily on the type of its right hand
argument. Moreover, its semantics have been adjusted for greater
consistency or usefulness in several cases. While the general backwards
compatibility is maintained, several changes must be noted:</p>
<ul>
<li>
<p>Code references with an empty prototype are no longer treated specially.
They are passed an argument like the other code references (even if they
choose to ignore it).</p>
</li>
<li>
<p><code class="inline"><span class="i">%hash</span> ~~ <a class="l_k" href="functions/sub.html">sub</a> <span class="s">{</span><span class="s">}</span></code>
 and <code class="inline"><span class="i">@array</span> ~~ <a class="l_k" href="functions/sub.html">sub</a> <span class="s">{</span><span class="s">}</span></code>
 now test that the subroutine
returns a true value for each key of the hash (or element of the
array), instead of passing the whole hash or array as a reference to
the subroutine.</p>
</li>
<li>
<p>Due to the commutativity breakage, code references are no longer
treated specially when appearing on the left of the <code class="inline">~~</code>
 operator,
but like any vulgar scalar.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/undef.html">undef</a> ~~ <span class="i">%hash</span></code>
 is always false (since <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> can't be a key in a
hash). No implicit conversion to <code class="inline"><span class="q">&quot;&quot;</span></code>
 is done (as was the case in perl
5.10.0).</p>
</li>
<li>
<p><code class="inline"><span class="i">$scalar</span> ~~ <span class="i">@array</span></code>
 now always distributes the smart match across the
elements of the array. It's true if one element in @array verifies
<code class="inline"><span class="i">$scalar</span> ~~ <span class="i">$element</span></code>
. This is a generalization of the old behaviour
that tested whether the array contained the scalar.</p>
</li>
</ul>
<p>The full dispatch table for the smart match operator is given in
<a href="perlsyn.html#Smart-matching-in-detail">Smart matching in detail in perlsyn</a>.</p>
<a name="Smart-match-and-overloading"></a><h3>Smart match and overloading</h3>
<p>According to the rule of dispatch based on the rightmost argument type,
when an object overloading <code class="inline">~~</code>
 appears on the right side of the
operator, the overload routine will always be called (with a 3rd argument
set to a true value, see <a href="overload.html">overload</a>.) However, when the object will
appear on the left, the overload routine will be called only when the
rightmost argument is a simple scalar. This way, distributivity of smart
match across arrays is not broken, as well as the other behaviours with
complex types (coderefs, hashes, regexes). Thus, writers of overloading
routines for smart match mostly need to worry only with comparing
against a scalar, and possibly with stringification overloading; the
other common cases will be automatically handled consistently.</p>
<p><code class="inline">~~</code>
 will now refuse to work on objects that do not overload it (in order
to avoid relying on the object's underlying structure). (However, if the
object overloads the stringification or the numification operators, and
if overload fallback is active, it will be used instead, as usual.)</p>
<a name="Other-potentially-incompatible-changes"></a><h2>Other potentially incompatible changes</h2>
<ul>
<li>
<p>The definitions of a number of Unicode properties have changed to match
those of the current Unicode standard. These are listed above under
<a href="#Unicode-overhaul">Unicode overhaul</a>. This change may break code that expects the old
definitions.</p>
</li>
<li>
<p>The boolkeys op has moved to the group of hash ops. This breaks binary
compatibility.</p>
</li>
<li>
<p>Filehandles are now always blessed into <code class="inline"><span class="w">IO::File</span></code>
.</p>
<p>The previous behaviour was to bless Filehandles into <a href="FileHandle.html">FileHandle</a>
(an empty proxy class) if it was loaded into memory and otherwise
to bless them into <code class="inline"><span class="w">IO::Handle</span></code>
.</p>
</li>
<li>
<p>The semantics of <code class="inline">use feature :5.10*</code> have changed slightly.
See <a href="#Modules-and-Pragmata">Modules and Pragmata</a> for more information.</p>
</li>
<li>
<p>Perl's developers now use git, rather than Perforce.  This should be
a purely internal change only relevant to people actively working on
the core.  However, you may see minor difference in perl as a consequence
of the change.  For example in some of details of the output of <code class="inline"><span class="w">perl</span>
-<span class="w">V</span></code>
. See <a href="perlrepository.html">perlrepository</a> for more information.</p>
</li>
<li>
<p>As part of the <code class="inline"><span class="w">Test::Harness</span></code>
 2.x to 3.x upgrade, the experimental
<code class="inline"><span class="w">Test::Harness::Straps</span></code>
 module has been removed.
See <a href="#Modules-and-Pragmata">Modules and Pragmata</a> for more details.</p>
</li>
<li>
<p>As part of the <code class="inline"><span class="w">ExtUtils::MakeMaker</span></code>
 upgrade, the
<code class="inline"><span class="w">ExtUtils::MakeMaker::bytes</span></code>
 and <code class="inline"><span class="w">ExtUtils::MakeMaker::vmsish</span></code>
 modules
have been removed from this distribution.</p>
</li>
<li>
<p><code class="inline"><span class="w">Module::CoreList</span></code>
 no longer contains the <code class="inline">%:patchlevel</code> hash.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/length.html">length</a> <a class="l_k" href="functions/undef.html">undef</a></code>
 now returns undef.</p>
</li>
<li>
<p>Unsupported private C API functions are now declared "static" to prevent
leakage to Perl's public API.</p>
</li>
<li>
<p>To support the bootstrapping process, <i>miniperl</i> no longer builds with
UTF-8 support in the regexp engine.</p>
<p>This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
Without this there's a bootstrapping problem, as miniperl can't load
the UTF-8 components of the regexp engine, because they're not yet built.</p>
</li>
<li>
<p><i>miniperl</i>'s @INC is now restricted to just <code class="inline">-<span class="w">I</span>...</code>
, the split of
<code class="inline"><span class="i">$ENV</span>{<span class="w">PERL5LIB</span>}</code>
, and "<code class="inline">.</code>"</p>
</li>
<li>
<p>A space or a newline is now required after a <code class="inline"><span class="q">&quot;#line XXX&quot;</span></code>
 directive.</p>
</li>
<li>
<p>Tied filehandles now have an additional method EOF which provides the
EOF type.</p>
</li>
<li>
<p>To better match all other flow control statements, <code class="inline">foreach</code>
 may no
longer be used as an attribute.</p>
</li>
<li>
<p>Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
now been removed. The CPAN module <code class="inline"><span class="w">Filter::cpp</span></code>
 can be used as an 
alternative.</p>
</li>
</ul>
<a name="Deprecations"></a><h1>Deprecations</h1>
<p>From time to time, Perl's developers find it necessary to deprecate
features or modules we've previously shipped as part of the core
distribution. We are well aware of the pain and frustration that a
backwards-incompatible change to Perl can cause for developers building
or maintaining software in Perl. You can be sure that when we deprecate
a functionality or syntax, it isn't a choice we make lightly. Sometimes,
we choose to deprecate functionality or syntax because it was found to
be poorly designed or implemented. Sometimes, this is because they're
holding back other features or causing performance problems. Sometimes,
the reasons are more complex. Wherever possible, we try to keep deprecated
functionality available to developers in its previous form for at least
one major release. So long as a deprecated feature isn't actively
disrupting our ability to maintain and extend Perl, we'll try to leave
it in place as long as possible.</p>
<p>The following items are now deprecated:</p>
<ul>
<li><a name="suidperl"></a><b>suidperl</b>
<p><code class="inline"><span class="w">suidperl</span></code>
 is no longer part of Perl. It used to provide a mechanism to
emulate setuid permission bits on systems that don't support it properly.</p>
</li>
<li><a name="Use-of-%3a%3d-to-mean-an-empty-attribute-list"></a><b>Use of <code class="inline"><span class="j">:</span>=</code>
 to mean an empty attribute list</b>
<p>An accident of Perl's parser meant that these constructions were all
equivalent:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$pi</span> <span class="co">:</span>= <span class="n">4</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$pi</span> <span class="co">:</span> = <span class="n">4</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$pi</span> <span class="co">:</span>  = <span class="n">4</span><span class="sc">;</span></li></ol></pre><p>with the <code class="inline"><span class="j">:</span></code>
 being treated as the start of an attribute list, which
ends before the <code class="inline">=</code>
. As whitespace is not significant here, all are
parsed as an empty attribute list, hence all the above are equivalent
to, and better written as</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$pi</span> = <span class="n">4</span><span class="sc">;</span></li></ol></pre><p>because no attribute processing is done for an empty list.</p>
<p>As is, this meant that <code class="inline"><span class="j">:</span>=</code>
 cannot be used as a new token, without
silently changing the meaning of existing code. Hence that particular
form is now deprecated, and will become a syntax error. If it is
absolutely necessary to have empty attribute lists (for example,
because of a code generator) then avoid the warning by adding a space
before the <code class="inline">=</code>
.</p>
</li>
<li><a name="UNIVERSAL-%3eimport()"></a><b><code class="inline"><span class="w">UNIVERSAL</span><span class="w">-&gt;import</span><span class="s">(</span><span class="s">)</span></code>
</b>
<p>The method <code class="inline"><span class="w">UNIVERSAL</span><span class="w">-&gt;import</span><span class="s">(</span><span class="s">)</span></code>
 is now deprecated. Attempting to
pass import arguments to a <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">UNIVERSAL</span></code>
 statement will result in a
deprecation warning.</p>
</li>
<li><a name="Use-of-%22goto%22-to-jump-into-a-construct"></a><b>Use of "goto" to jump into a construct</b>
<p>Using <code class="inline"><a class="l_k" href="functions/goto.html">goto</a></code> to jump from an outer scope into an inner scope is now
deprecated. This rare use case was causing problems in the
implementation of scopes.</p>
</li>
<li><a name="Custom-character-names-in-%5cN%7bname%7d-that-don't-look-like-names"></a><b>Custom character names in \N{name} that don't look like names</b>
<p>In <code class="inline">\N{<i>name</i>}</code>, <i>name</i> can be just about anything. The standard
Unicode names have a very limited domain, but a custom name translator
could create names that are, for example, made up entirely of punctuation
symbols. It is now deprecated to make names that don't begin with an
alphabetic character, and aren't alphanumeric or contain other than
a very few other characters, namely spaces, dashes, parentheses
and colons. Because of the added meaning of <code class="inline">\<span class="w">N</span></code>
 (See <a href="#%5cN-experimental-regex-escape">\N experimental regex escape</a>), names that look like curly brace -enclosed
quantifiers won't work. For example, <code class="inline">\<span class="w">N</span><span class="s">{</span><span class="n">3</span><span class="cm">,</span><span class="n">4</span><span class="s">}</span></code>
 now means to match 3 to
4 non-newlines; before a custom name <code class="inline"><span class="n">3</span><span class="cm">,</span><span class="n">4</span></code>
 could have been created.</p>
</li>
<li><a name="Deprecated-Modules"></a><b>Deprecated Modules</b>
<p>The following modules will be removed from the core distribution in a
future release, and should be installed from CPAN instead. Distributions
on CPAN which require these should add them to their prerequisites. The
core versions of these modules warnings will issue a deprecation warning.</p>
<p>If you ship a packaged version of Perl, either alone or as part of a
larger system, then you should carefully consider the repercussions of
core module deprecations. You may want to consider shipping your default
build of Perl with packages for some or all deprecated modules which
install into <code class="inline"><span class="w">vendor</span></code>
 or <code class="inline"><span class="w">site</span></code>
 perl library directories. This will
inhibit the deprecation warnings.</p>
<p>Alternatively, you may want to consider patching <i>lib/deprecate.pm</i>
to provide deprecation warnings specific to your packaging system
or distribution of Perl, consistent with how your packaging system
or distribution manages a staged transition from a release where the
installation of a single package provides the given functionality, to
a later release where the system administrator needs to know to install
multiple packages to get that same functionality.</p>
<p>You can silence these deprecation warnings by installing the modules
in question from CPAN.  To install the latest version of all of them,
just install <code class="inline"><span class="w">Task::Deprecations::5_12</span></code>
.</p>
<ul>
<li><a name="the-Class%3a%3aISA-manpage"></a><b><a href="http://search.cpan.org/perldoc/Class::ISA">Class::ISA</a></b>
</li>
<li><a name="the-Pod%3a%3aPlainer-manpage"></a><b><a href="http://search.cpan.org/perldoc/Pod::Plainer">Pod::Plainer</a></b>
</li>
<li><a name="the-Shell-manpage"></a><b><a href="http://search.cpan.org/perldoc/Shell">Shell</a></b>
</li>
<li><a name="the-Switch-manpage"></a><b><a href="http://search.cpan.org/perldoc/Switch">Switch</a></b>
<p>Switch is buggy and should be avoided. You may find Perl's new
<code class="inline">given</code>
/<code class="inline">when</code>
 feature a suitable replacement.  See <a href="perlsyn.html#Switch-statements">Switch statements in perlsyn</a> for more information.</p>
</li>
</ul>
</li>
<li><a name="Assignment-to-%24%5b"></a><b>Assignment to $[</b>
</li>
<li><a name="Use-of-the-attribute-%3alocked-on-subroutines"></a><b>Use of the attribute :locked on subroutines</b>
</li>
<li><a name="Use-of-%22locked%22-with-the-attributes-pragma"></a><b>Use of "locked" with the attributes pragma</b>
</li>
<li><a name="Use-of-%22unique%22-with-the-attributes-pragma"></a><b>Use of "unique" with the attributes pragma</b>
</li>
<li><a name="Perl_pmflag"></a><b>Perl_pmflag</b>
<p><code class="inline"><span class="w">Perl_pmflag</span></code>
 is no longer part of Perl's public API. Calling it now
generates a deprecation warning, and it will be removed in a future
release. Although listed as part of the API, it was never documented,
and only ever used in <i>toke.c</i>, and prior to 5.10, <i>regcomp.c</i>. In
core, it has been replaced by a static function.</p>
</li>
<li><a name="Numerous-Perl-4-era-libraries"></a><b>Numerous Perl 4-era libraries</b>
<p><i>termcap.pl</i>, <i>tainted.pl</i>, <i>stat.pl</i>, <i>shellwords.pl</i>, <i>pwd.pl</i>,
<i>open3.pl</i>, <i>open2.pl</i>, <i>newgetopt.pl</i>, <i>look.pl</i>, <i>find.pl</i>,
<i>finddepth.pl</i>, <i>importenv.pl</i>, <i>hostname.pl</i>, <i>getopts.pl</i>,
<i>getopt.pl</i>, <i>getcwd.pl</i>, <i>flush.pl</i>, <i>fastcwd.pl</i>, <i>exceptions.pl</i>,
<i>ctime.pl</i>, <i>complete.pl</i>, <i>cacheout.pl</i>, <i>bigrat.pl</i>, <i>bigint.pl</i>,
<i>bigfloat.pl</i>, <i>assert.pl</i>, <i>abbrev.pl</i>, <i>dotsh.pl</i>, and
<i>timelocal.pl</i> are all now deprecated.  Earlier, Perl's developers
intended to remove these libraries from Perl's core for the 5.14.0 release.</p>
<p>During final testing before the release of 5.12.0, several developers
discovered current production code using these ancient libraries, some
inside the Perl core itself.  Accordingly, the pumpking granted them
a stay of execution. They will begin to warn about their deprecation
in the 5.14.0 release and will be removed in the 5.16.0 release.</p>
</li>
</ul>
<a name="Unicode-overhaul"></a><h1>Unicode overhaul</h1>
<p>Perl's developers have made a concerted effort to update Perl to be in
sync with the latest Unicode standard. Changes for this include:</p>
<p>Perl can now handle every Unicode character property. New documentation,
<a href="perluniprops.html">perluniprops</a>, lists all available non-Unihan character properties. By
default, perl does not expose Unihan, deprecated or Unicode-internal
properties.  See below for more details on these; there is also a section
in the pod listing them, and explaining why they are not exposed.</p>
<p>Perl now fully supports the Unicode compound-style of using <code class="inline">=</code>

and <code class="inline"><span class="j">:</span></code>
 in writing regular expressions: <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">property</span>=<span class="w">value</span><span class="s">}</span></code>
 and
<code class="inline">\<span class="i">p</span><span class="s">{</span><span class="j">property:</span><span class="w">value</span><span class="s">}</span></code>
 (both of which mean the same thing).</p>
<p>Perl now fully supports the Unicode loose matching rules for text between
the braces in <code class="inline">\<span class="i">p</span><span class="s">{</span>...<span class="s">}</span></code>
 constructs. In addition, Perl allows underscores
between digits of numbers.</p>
<p>Perl now accepts all the Unicode-defined synonyms for properties and
property values.</p>
<p><code class="inline"><a class="l_k" href="functions/qr.html">qr/\X/</a></code>, which matches a Unicode logical character, has
been expanded to work better with various Asian languages. It
now is defined as an <i>extended grapheme cluster</i>. (See
<a href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>).  Anything matched previously
and that made sense will continue to be accepted.   Additionally:</p>
<ul>
<li>
<p><code class="inline">\<span class="w">X</span></code>
 will not break apart a <code class="inline"><span class="w">CR</span> <span class="w">LF</span></code>
 sequence.</p>
</li>
<li>
<p><code class="inline">\<span class="w">X</span></code>
 will now match a sequence which includes the <code class="inline"><span class="w">ZWJ</span></code>
 and <code class="inline"><span class="w">ZWNJ</span></code>

characters.</p>
</li>
<li>
<p><code class="inline">\<span class="w">X</span></code>
 will now always match at least one character, including an initial
mark.  Marks generally come after a base character, but it is possible in
Unicode to have them in isolation, and <code class="inline">\<span class="w">X</span></code>
 will now handle that case,
for example at the beginning of a line, or after a <code class="inline"><span class="w">ZWSP</span></code>
. And this is
the part where <code class="inline">\<span class="w">X</span></code>
 doesn't match the things that it used to that don't
make sense. Formerly, for example, you could have the nonsensical case
of an accented LF.</p>
</li>
<li>
<p><code class="inline">\<span class="w">X</span></code>
 will now match a (Korean) Hangul syllable sequence, and the Thai
and Lao exception cases.</p>
</li>
</ul>
<p>Otherwise, this change should be transparent for the non-affected
languages.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span>...<span class="s">}</span></code>
 matches using the Canonical_Combining_Class property were
completely broken in previous releases of Perl.  They should now work
correctly.</p>
<p>Before Perl 5.12, the Unicode <code class="inline"><span class="w">Decomposition_Type</span>=<span class="w">Compat</span></code>
 property
and a Perl extension had the same name, which led to neither matching
all the correct values (with more than 100 mistakes in one, and several
thousand in the other). The Perl extension has now been renamed to be
<code class="inline"><span class="w">Decomposition_Type</span>=<span class="w">Noncanonical</span></code>
 (short: <code class="inline"><span class="w">dt</span>=<span class="w">noncanon</span></code>
). It has the
same meaning as was previously intended, namely the union of all the
non-canonical Decomposition types, with Unicode <code class="inline"><span class="w">Compat</span></code>
 being just
one of those.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Decomposition_Type</span>=<span class="w">Canonical</span><span class="s">}</span></code>
 now includes the Hangul syllables.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Uppercase</span><span class="s">}</span></code>
 and <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Lowercase</span><span class="s">}</span></code>
 now work as the Unicode standard
says they should.  This means they each match a few more characters than
they used to.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Cntrl</span><span class="s">}</span></code>
 now matches the same characters as <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Control</span><span class="s">}</span></code>
. This
means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
nor Format (gc=cf) code points. The Format code points represent the
biggest possible problem. All but 36 of them are either officially
deprecated or strongly discouraged from being used. Of those 36, likely
the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
WJ, and similar characters, plus bidirectional controls.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Alpha</span><span class="s">}</span></code>
 now matches the same characters as <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Alphabetic</span><span class="s">}</span></code>
. Before
5.12, Perl's definition included a number of things that aren't
really alpha (all marks) while omitting many that were. The definitions
of <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Alnum</span><span class="s">}</span></code>
 and <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Word</span><span class="s">}</span></code>
 depend on Alpha's definition and have
changed accordingly.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Word</span><span class="s">}</span></code>
 no longer incorrectly matches non-word characters such
as fractions.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Print</span><span class="s">}</span></code>
 no longer matches the line control characters: Tab, LF,
CR, FF, VT, and NEL. This brings it in line with standards and the
documentation.</p>
<p><code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">XDigit</span><span class="s">}</span></code>
 now matches the same characters as <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Hex_Digit</span><span class="s">}</span></code>
. This
means that in addition to the characters it currently matches,
<code class="inline"><span class="s">[</span><span class="w">A</span>-<span class="w">Fa</span>-<span class="w">f0</span>-<span class="n">9</span><span class="s">]</span></code>
, it will also match the 22 fullwidth equivalents, for
example U+FF10: FULLWIDTH DIGIT ZERO.</p>
<p>The Numeric type property has been extended to include the Unihan
characters.</p>
<p>There is a new Perl extension, the 'Present_In', or simply 'In',
property. This is an extension of the Unicode Age property, but
<code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">In</span>=<span class="n">5.0</span><span class="s">}</span></code>
 matches any code point whose usage has been determined
<i>as of</i> Unicode version 5.0. The <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Age</span>=<span class="n">5.0</span><span class="s">}</span></code>
 only matches code points
added in <i>precisely</i> version 5.0.</p>
<p>A number of properties now have the correct values for unassigned
code points. The affected properties are Bidi_Class, East_Asian_Width,
Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
and Line_Break.</p>
<p>The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
are now up to date with current Unicode definitions.</p>
<p>Earlier versions of Perl erroneously exposed certain properties that
are supposed to be Unicode internal-only.  Use of these in regular
expressions will now generate, if enabled, a deprecation warning message.
The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
Other_Math, and Other_Uppercase.</p>
<p>It is now possible to change which Unicode properties Perl understands
on a per-installation basis. As mentioned above, certain properties
are turned off by default.  These include all the Unihan properties
(which should be accessible via the CPAN module Unicode::Unihan) and any
deprecated or Unicode internal-only property that Perl has never exposed.</p>
<p>The generated files in the <code class="inline"><span class="w">lib</span>/<span class="w">unicore</span>/<span class="w">To</span></code>
 directory are now more
clearly marked as being stable, directly usable by applications.  New hash
entries in them give the format of the normal entries, which allows for
easier machine parsing. Perl can generate files in this directory for
any property, though most are suppressed.  You can find instructions
for changing which are written in <a href="perluniprops.html">perluniprops</a>.</p>
<a name="Modules-and-Pragmata"></a><h1>Modules and Pragmata</h1>
<a name="New-Modules-and-Pragmata"></a><h2>New Modules and Pragmata</h2>
<ul>
<li><a name="autodie"></a><b><code class="inline"><span class="w">autodie</span></code>
</b>
<p><code class="inline"><span class="w">autodie</span></code>
 is a new lexically-scoped alternative for the <code class="inline"><span class="w">Fatal</span></code>
 module.
The bundled version is 2.06_01. Note that in this release, using a string
eval when <code class="inline"><span class="w">autodie</span></code>
 is in effect can cause the autodie behaviour to leak
into the surrounding scope. See <a href="autodie.html#BUGS">BUGS in autodie</a> for more details.</p>
<p>Version 2.06_01 has been added to the Perl core.</p>
</li>
<li><a name="Compress%3a%3aRaw%3a%3aBzip2"></a><b><code class="inline"><span class="w">Compress::Raw::Bzip2</span></code>
</b>
<p>Version 2.024 has been added to the Perl core.</p>
</li>
<li><a name="overloading"></a><b><code class="inline"><span class="w">overloading</span></code>
</b>
<p><code class="inline"><span class="w">overloading</span></code>
 allows you to lexically disable or enable overloading
for some or all operations.</p>
<p>Version 0.001 has been added to the Perl core.</p>
</li>
<li><a name="parent"></a><b><code class="inline"><span class="w">parent</span></code>
</b>
<p><code class="inline"><span class="w">parent</span></code>
 establishes an ISA relationship with base classes at compile
time. It provides the key feature of <code class="inline"><span class="w">base</span></code>
 without further unwanted
behaviors.</p>
<p>Version 0.223 has been added to the Perl core.</p>
</li>
<li><a name="Parse%3a%3aCPAN%3a%3aMeta"></a><b><code class="inline"><span class="w">Parse::CPAN::Meta</span></code>
</b>
<p>Version 1.40 has been added to the Perl core.</p>
</li>
<li><a name="VMS%3a%3aDCLsym"></a><b><code class="inline"><span class="w">VMS::DCLsym</span></code>
</b>
<p>Version 1.03 has been added to the Perl core.</p>
</li>
<li><a name="VMS%3a%3aStdio"></a><b><code class="inline"><span class="w">VMS::Stdio</span></code>
</b>
<p>Version 2.4 has been added to the Perl core.</p>
</li>
<li><a name="XS%3a%3aAPItest%3a%3aKeywordRPN"></a><b><code class="inline"><span class="w">XS::APItest::KeywordRPN</span></code>
</b>
<p>Version 0.003 has been added to the Perl core.</p>
</li>
</ul>
<a name="Updated-Pragmata"></a><h2>Updated Pragmata</h2>
<ul>
<li><a name="base"></a><b><code class="inline"><span class="w">base</span></code>
</b>
<p>Upgraded from version 2.13 to 2.15.</p>
</li>
<li><a name="bignum"></a><b><code class="inline"><span class="w">bignum</span></code>
</b>
<p>Upgraded from version 0.22 to 0.23.</p>
</li>
<li><a name="charnames"></a><b><code class="inline"><span class="w">charnames</span></code>
</b>
<p><code class="inline"><span class="w">charnames</span></code>
 now contains the Unicode <i>NameAliases.txt</i> database file.
This has the effect of adding some extra <code class="inline">\<span class="w">N</span></code>
 character names that
formerly wouldn't have been recognised; for example, <code class="inline"><span class="q">&quot;\N{LATIN CAPITAL</span>
<span class="q">LETTER GHA}&quot;</span></code>
.</p>
<p>Upgraded from version 1.06 to 1.07.</p>
</li>
<li><a name="constant"></a><b><code class="inline"><span class="w">constant</span></code>
</b>
<p>Upgraded from version 1.13 to 1.20.</p>
</li>
<li><a name="diagnostics"></a><b><code class="inline"><span class="w">diagnostics</span></code>
</b>
<p><code class="inline"><span class="w">diagnostics</span></code>
 now supports %.0f formatting internally.</p>
<p><code class="inline"><span class="w">diagnostics</span></code>
 no longer suppresses <code class="inline"><span class="w">Use</span> <span class="w">of</span> <span class="w">uninitialized</span> <span class="w">value</span> <span class="w">in</span> <span class="i">range</span>
<span class="s">(</span>or <span class="w">flip</span><span class="s">)</span></code>
 warnings. [perl #71204]</p>
<p>Upgraded from version 1.17 to 1.19.</p>
</li>
<li><a name="feature"></a><b><code class="inline"><span class="w">feature</span></code>
</b>
<p>In <code class="inline"><span class="w">feature</span></code>
, the meaning of the <code class="inline"><span class="j">:</span><span class="n">5.10</span></code>
 and <code class="inline"><span class="j">:</span><span class="n">5.10</span>.<span class="w">X</span></code>
 feature
bundles has changed slightly. The last component, if any (i.e. <code class="inline"><span class="w">X</span></code>
) is
simply ignored.  This is predicated on the assumption that new features
will not, in general, be added to maintenance releases. So <code class="inline"><span class="j">:</span><span class="n">5.10</span></code>

and <code class="inline"><span class="j">:</span><span class="n">5.10</span>.<span class="w">X</span></code>
 have identical effect. This is a change to the behaviour
documented for 5.10.0.</p>
<p><code class="inline"><span class="w">feature</span></code>
 now includes the <code class="inline"><span class="w">unicode_strings</span></code>
 feature:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">feature</span> <span class="q">&quot;unicode_strings&quot;</span><span class="sc">;</span></li></ol></pre><p>This pragma turns on Unicode semantics for the case-changing operations
(<code class="inline"><a class="l_k" href="functions/uc.html">uc</a></code>, <code class="inline"><a class="l_k" href="functions/lc.html">lc</a></code>, <code class="inline"><a class="l_k" href="functions/ucfirst.html">ucfirst</a></code>, <code class="inline"><a class="l_k" href="functions/lcfirst.html">lcfirst</a></code>) on strings that don't have the
internal UTF-8 flag set, but that contain single-byte characters between
128 and 255.</p>
<p>Upgraded from version 1.11 to 1.16.</p>
</li>
<li><a name="less"></a><b><code class="inline"><span class="w">less</span></code>
</b>
<p><code class="inline"><span class="w">less</span></code>
 now includes the <code class="inline"><span class="w">stash_name</span></code>
 method to allow subclasses of
<code class="inline"><span class="w">less</span></code>
 to pick where in %^H to store their stash.</p>
<p>Upgraded from version 0.02 to 0.03.</p>
</li>
<li><a name="lib"></a><b><code class="inline"><span class="w">lib</span></code>
</b>
<p>Upgraded from version 0.5565 to 0.62.</p>
</li>
<li><a name="mro"></a><b><code class="inline"><span class="w">mro</span></code>
</b>
<p><code class="inline"><span class="w">mro</span></code>
 is now implemented as an XS extension. The documented interface has
not changed. Code relying on the implementation detail that some <code class="inline"><span class="w">mro::</span></code>

methods happened to be available at all times gets to "keep both pieces".</p>
<p>Upgraded from version 1.00 to 1.02.</p>
</li>
<li><a name="overload"></a><b><code class="inline"><span class="w">overload</span></code>
</b>
<p><code class="inline"><span class="w">overload</span></code>
 now allow overloading of 'qr'.</p>
<p>Upgraded from version 1.06 to 1.10.</p>
</li>
<li><a name="threads"></a><b><code class="inline"><span class="w">threads</span></code>
</b>
<p>Upgraded from version 1.67 to 1.75.</p>
</li>
<li><a name="threads%3a%3ashared"></a><b><code class="inline"><span class="w">threads::shared</span></code>
</b>
<p>Upgraded from version 1.14 to 1.32.</p>
</li>
<li><a name="version"></a><b><code class="inline"><span class="w">version</span></code>
</b>
<p><code class="inline"><span class="w">version</span></code>
 now has support for <a href="#Version-number-formats">Version number formats</a> as described
earlier in this document and in its own documentation.</p>
<p>Upgraded from version 0.74 to 0.82.</p>
</li>
<li><a name="warnings"></a><b><code class="inline"><span class="w">warnings</span></code>
</b>
<p><code class="inline"><span class="w">warnings</span></code>
 has a new <code class="inline"><span class="i">warnings::fatal_enabled</span><span class="s">(</span><span class="s">)</span></code>
 function.  It also
includes a new <code class="inline"><span class="w">illegalproto</span></code>
 warning category. See also <a href="#New-or-Changed-Diagnostics">New or Changed Diagnostics</a> for this change.</p>
<p>Upgraded from version 1.06 to 1.09.</p>
</li>
</ul>
<a name="Updated-Modules"></a><h2>Updated Modules</h2>
<ul>
<li><a name="Archive%3a%3aExtract"></a><b><code class="inline"><span class="w">Archive::Extract</span></code>
</b>
<p>Upgraded from version 0.24 to 0.38.</p>
</li>
<li><a name="Archive%3a%3aTar"></a><b><code class="inline"><span class="w">Archive::Tar</span></code>
</b>
<p>Upgraded from version 1.38 to 1.54.</p>
</li>
<li><a name="Attribute%3a%3aHandlers"></a><b><code class="inline"><span class="w">Attribute::Handlers</span></code>
</b>
<p>Upgraded from version 0.79 to 0.87.</p>
</li>
<li><a name="AutoLoader"></a><b><code class="inline"><span class="w">AutoLoader</span></code>
</b>
<p>Upgraded from version 5.63 to 5.70.</p>
</li>
<li><a name="B%3a%3aConcise"></a><b><code class="inline"><span class="w">B::Concise</span></code>
</b>
<p>Upgraded from version 0.74 to 0.78.</p>
</li>
<li><a name="B%3a%3aDebug"></a><b><code class="inline"><span class="w">B::Debug</span></code>
</b>
<p>Upgraded from version 1.05 to 1.12.</p>
</li>
<li><a name="B%3a%3aDeparse"></a><b><code class="inline"><span class="w">B::Deparse</span></code>
</b>
<p>Upgraded from version 0.83 to 0.96.</p>
</li>
<li><a name="B%3a%3aLint"></a><b><code class="inline"><span class="w">B::Lint</span></code>
</b>
<p>Upgraded from version 1.09 to 1.11_01.</p>
</li>
<li><a name="CGI"></a><b><code class="inline"><span class="w">CGI</span></code>
</b>
<p>Upgraded from version 3.29 to 3.48.</p>
</li>
<li><a name="Class%3a%3aISA"></a><b><code class="inline"><span class="w">Class::ISA</span></code>
</b>
<p>Upgraded from version 0.33 to 0.36.</p>
<p>NOTE: <code class="inline"><span class="w">Class::ISA</span></code>
 is deprecated and may be removed from a future
version of Perl.</p>
</li>
<li><a name="Compress%3a%3aRaw%3a%3aZlib"></a><b><code class="inline"><span class="w">Compress::Raw::Zlib</span></code>
</b>
<p>Upgraded from version 2.008 to 2.024.</p>
</li>
<li><a name="CPAN"></a><b><code class="inline"><span class="w">CPAN</span></code>
</b>
<p>Upgraded from version 1.9205 to 1.94_56.</p>
</li>
<li><a name="CPANPLUS"></a><b><code class="inline"><span class="w">CPANPLUS</span></code>
</b>
<p>Upgraded from version 0.84 to 0.90.</p>
</li>
<li><a name="CPANPLUS%3a%3aDist%3a%3aBuild"></a><b><code class="inline"><span class="w">CPANPLUS::Dist::Build</span></code>
</b>
<p>Upgraded from version 0.06_02 to 0.46.</p>
</li>
<li><a name="Data%3a%3aDumper"></a><b><code class="inline"><span class="w">Data::Dumper</span></code>
</b>
<p>Upgraded from version 2.121_14 to 2.125.</p>
</li>
<li><a name="DB_File"></a><b><code class="inline"><span class="w">DB_File</span></code>
</b>
<p>Upgraded from version 1.816_1 to 1.820.</p>
</li>
<li><a name="Devel%3a%3aPPPort"></a><b><code class="inline"><span class="w">Devel::PPPort</span></code>
</b>
<p>Upgraded from version 3.13 to 3.19.</p>
</li>
<li><a name="Digest"></a><b><code class="inline"><span class="w">Digest</span></code>
</b>
<p>Upgraded from version 1.15 to 1.16.</p>
</li>
<li><a name="Digest%3a%3aMD5"></a><b><code class="inline"><span class="w">Digest::MD5</span></code>
</b>
<p>Upgraded from version 2.36_01 to 2.39.</p>
</li>
<li><a name="Digest%3a%3aSHA"></a><b><code class="inline"><span class="w">Digest::SHA</span></code>
</b>
<p>Upgraded from version 5.45 to 5.47.</p>
</li>
<li><a name="Encode"></a><b><code class="inline"><span class="w">Encode</span></code>
</b>
<p>Upgraded from version 2.23 to 2.39.</p>
</li>
<li><a name="Exporter"></a><b><code class="inline"><span class="w">Exporter</span></code>
</b>
<p>Upgraded from version 5.62 to 5.64_01.</p>
</li>
<li><a name="ExtUtils%3a%3aCBuilder"></a><b><code class="inline"><span class="w">ExtUtils::CBuilder</span></code>
</b>
<p>Upgraded from version 0.21 to 0.27.</p>
</li>
<li><a name="ExtUtils%3a%3aCommand"></a><b><code class="inline"><span class="w">ExtUtils::Command</span></code>
</b>
<p>Upgraded from version 1.13 to 1.16.</p>
</li>
<li><a name="ExtUtils%3a%3aConstant"></a><b><code class="inline"><span class="w">ExtUtils::Constant</span></code>
</b>
<p>Upgraded from version 0.2 to 0.22.</p>
</li>
<li><a name="ExtUtils%3a%3aInstall"></a><b><code class="inline"><span class="w">ExtUtils::Install</span></code>
</b>
<p>Upgraded from version 1.44 to 1.55.</p>
</li>
<li><a name="ExtUtils%3a%3aMakeMaker"></a><b><code class="inline"><span class="w">ExtUtils::MakeMaker</span></code>
</b>
<p>Upgraded from version 6.42 to 6.56.</p>
</li>
<li><a name="ExtUtils%3a%3aManifest"></a><b><code class="inline"><span class="w">ExtUtils::Manifest</span></code>
</b>
<p>Upgraded from version 1.51_01 to 1.57.</p>
</li>
<li><a name="ExtUtils%3a%3aParseXS"></a><b><code class="inline"><span class="w">ExtUtils::ParseXS</span></code>
</b>
<p>Upgraded from version 2.18_02 to 2.21.</p>
</li>
<li><a name="File%3a%3aFetch"></a><b><code class="inline"><span class="w">File::Fetch</span></code>
</b>
<p>Upgraded from version 0.14 to 0.24.</p>
</li>
<li><a name="File%3a%3aPath"></a><b><code class="inline"><span class="w">File::Path</span></code>
</b>
<p>Upgraded from version 2.04 to 2.08_01.</p>
</li>
<li><a name="File%3a%3aTemp"></a><b><code class="inline"><span class="w">File::Temp</span></code>
</b>
<p>Upgraded from version 0.18 to 0.22.</p>
</li>
<li><a name="Filter%3a%3aSimple"></a><b><code class="inline"><span class="w">Filter::Simple</span></code>
</b>
<p>Upgraded from version 0.82 to 0.84.</p>
</li>
<li><a name="Filter%3a%3aUtil%3a%3aCall"></a><b><code class="inline"><span class="w">Filter::Util::Call</span></code>
</b>
<p>Upgraded from version 1.07 to 1.08.</p>
</li>
<li><a name="Getopt%3a%3aLong"></a><b><code class="inline"><span class="w">Getopt::Long</span></code>
</b>
<p>Upgraded from version 2.37 to 2.38.</p>
</li>
<li><a name="IO"></a><b><code class="inline"><span class="w">IO</span></code>
</b>
<p>Upgraded from version 1.23_01 to 1.25_02.</p>
</li>
<li><a name="IO%3a%3aZlib"></a><b><code class="inline"><span class="w">IO::Zlib</span></code>
</b>
<p>Upgraded from version 1.07 to 1.10.</p>
</li>
<li><a name="IPC%3a%3aCmd"></a><b><code class="inline"><span class="w">IPC::Cmd</span></code>
</b>
<p>Upgraded from version 0.40_1 to 0.54.</p>
</li>
<li><a name="IPC%3a%3aSysV"></a><b><code class="inline"><span class="w">IPC::SysV</span></code>
</b>
<p>Upgraded from version 1.05 to 2.01.</p>
</li>
<li><a name="Locale%3a%3aMaketext"></a><b><code class="inline"><span class="w">Locale::Maketext</span></code>
</b>
<p>Upgraded from version 1.12 to 1.14.</p>
</li>
<li><a name="Locale%3a%3aMaketext%3a%3aSimple"></a><b><code class="inline"><span class="w">Locale::Maketext::Simple</span></code>
</b>
<p>Upgraded from version 0.18 to 0.21.</p>
</li>
<li><a name="Log%3a%3aMessage"></a><b><code class="inline"><span class="w">Log::Message</span></code>
</b>
<p>Upgraded from version 0.01 to 0.02.</p>
</li>
<li><a name="Log%3a%3aMessage%3a%3aSimple"></a><b><code class="inline"><span class="w">Log::Message::Simple</span></code>
</b>
<p>Upgraded from version 0.04 to 0.06.</p>
</li>
<li><a name="Math%3a%3aBigInt"></a><b><code class="inline"><span class="w">Math::BigInt</span></code>
</b>
<p>Upgraded from version 1.88 to 1.89_01.</p>
</li>
<li><a name="Math%3a%3aBigInt%3a%3aFastCalc"></a><b><code class="inline"><span class="w">Math::BigInt::FastCalc</span></code>
</b>
<p>Upgraded from version 0.16 to 0.19.</p>
</li>
<li><a name="Math%3a%3aBigRat"></a><b><code class="inline"><span class="w">Math::BigRat</span></code>
</b>
<p>Upgraded from version 0.21 to 0.24.</p>
</li>
<li><a name="Math%3a%3aComplex"></a><b><code class="inline"><span class="w">Math::Complex</span></code>
</b>
<p>Upgraded from version 1.37 to 1.56.</p>
</li>
<li><a name="Memoize"></a><b><code class="inline"><span class="w">Memoize</span></code>
</b>
<p>Upgraded from version 1.01_02 to 1.01_03.</p>
</li>
<li><a name="MIME%3a%3aBase64"></a><b><code class="inline"><span class="w">MIME::Base64</span></code>
</b>
<p>Upgraded from version 3.07_01 to 3.08.</p>
</li>
<li><a name="Module%3a%3aBuild"></a><b><code class="inline"><span class="w">Module::Build</span></code>
</b>
<p>Upgraded from version 0.2808_01 to 0.3603.</p>
</li>
<li><a name="Module%3a%3aCoreList"></a><b><code class="inline"><span class="w">Module::CoreList</span></code>
</b>
<p>Upgraded from version 2.12 to 2.29.</p>
</li>
<li><a name="Module%3a%3aLoad"></a><b><code class="inline"><span class="w">Module::Load</span></code>
</b>
<p>Upgraded from version 0.12 to 0.16.</p>
</li>
<li><a name="Module%3a%3aLoad%3a%3aConditional"></a><b><code class="inline"><span class="w">Module::Load::Conditional</span></code>
</b>
<p>Upgraded from version 0.22 to 0.34.</p>
</li>
<li><a name="Module%3a%3aLoaded"></a><b><code class="inline"><span class="w">Module::Loaded</span></code>
</b>
<p>Upgraded from version 0.01 to 0.06.</p>
</li>
<li><a name="Module%3a%3aPluggable"></a><b><code class="inline"><span class="w">Module::Pluggable</span></code>
</b>
<p>Upgraded from version 3.6 to 3.9.</p>
</li>
<li><a name="Net%3a%3aPing"></a><b><code class="inline"><span class="w">Net::Ping</span></code>
</b>
<p>Upgraded from version 2.33 to 2.36.</p>
</li>
<li><a name="NEXT"></a><b><code class="inline"><span class="w">NEXT</span></code>
</b>
<p>Upgraded from version 0.60_01 to 0.64.</p>
</li>
<li><a name="Object%3a%3aAccessor"></a><b><code class="inline"><span class="w">Object::Accessor</span></code>
</b>
<p>Upgraded from version 0.32 to 0.36.</p>
</li>
<li><a name="Package%3a%3aConstants"></a><b><code class="inline"><span class="w">Package::Constants</span></code>
</b>
<p>Upgraded from version 0.01 to 0.02.</p>
</li>
<li><a name="PerlIO"></a><b><code class="inline"><span class="w">PerlIO</span></code>
</b>
<p>Upgraded from version 1.04 to 1.06.</p>
</li>
<li><a name="Pod%3a%3aParser"></a><b><code class="inline"><span class="w">Pod::Parser</span></code>
</b>
<p>Upgraded from version 1.35 to 1.37.</p>
</li>
<li><a name="Pod%3a%3aPerldoc"></a><b><code class="inline"><span class="w">Pod::Perldoc</span></code>
</b>
<p>Upgraded from version 3.14_02 to 3.15_02.</p>
</li>
<li><a name="Pod%3a%3aPlainer"></a><b><code class="inline"><span class="w">Pod::Plainer</span></code>
</b>
<p>Upgraded from version 0.01 to 1.02.</p>
<p>NOTE: <code class="inline"><span class="w">Pod::Plainer</span></code>
 is deprecated and may be removed from a future
version of Perl.</p>
</li>
<li><a name="Pod%3a%3aSimple"></a><b><code class="inline"><span class="w">Pod::Simple</span></code>
</b>
<p>Upgraded from version 3.05 to 3.13.</p>
</li>
<li><a name="Safe"></a><b><code class="inline"><span class="w">Safe</span></code>
</b>
<p>Upgraded from version 2.12 to 2.22.</p>
</li>
<li><a name="SelfLoader"></a><b><code class="inline"><span class="w">SelfLoader</span></code>
</b>
<p>Upgraded from version 1.11 to 1.17.</p>
</li>
<li><a name="Storable"></a><b><code class="inline"><span class="w">Storable</span></code>
</b>
<p>Upgraded from version 2.18 to 2.22.</p>
</li>
<li><a name="Switch"></a><b><code class="inline"><span class="w">Switch</span></code>
</b>
<p>Upgraded from version 2.13 to 2.16.</p>
<p>NOTE: <code class="inline"><span class="w">Switch</span></code>
 is deprecated and may be removed from a future version
of Perl.</p>
</li>
<li><a name="Sys%3a%3aSyslog"></a><b><code class="inline"><span class="w">Sys::Syslog</span></code>
</b>
<p>Upgraded from version 0.22 to 0.27.</p>
</li>
<li><a name="Term%3a%3aANSIColor"></a><b><code class="inline"><span class="w">Term::ANSIColor</span></code>
</b>
<p>Upgraded from version 1.12 to 2.02.</p>
</li>
<li><a name="Term%3a%3aUI"></a><b><code class="inline"><span class="w">Term::UI</span></code>
</b>
<p>Upgraded from version 0.18 to 0.20.</p>
</li>
<li><a name="Test"></a><b><code class="inline"><span class="w">Test</span></code>
</b>
<p>Upgraded from version 1.25 to 1.25_02.</p>
</li>
<li><a name="Test%3a%3aHarness"></a><b><code class="inline"><span class="w">Test::Harness</span></code>
</b>
<p>Upgraded from version 2.64 to 3.17.</p>
</li>
<li><a name="Test%3a%3aSimple"></a><b><code class="inline"><span class="w">Test::Simple</span></code>
</b>
<p>Upgraded from version 0.72 to 0.94.</p>
</li>
<li><a name="Text%3a%3aBalanced"></a><b><code class="inline"><span class="w">Text::Balanced</span></code>
</b>
<p>Upgraded from version 2.0.0 to 2.02.</p>
</li>
<li><a name="Text%3a%3aParseWords"></a><b><code class="inline"><span class="w">Text::ParseWords</span></code>
</b>
<p>Upgraded from version 3.26 to 3.27.</p>
</li>
<li><a name="Text%3a%3aSoundex"></a><b><code class="inline"><span class="w">Text::Soundex</span></code>
</b>
<p>Upgraded from version 3.03 to 3.03_01.</p>
</li>
<li><a name="Thread%3a%3aQueue"></a><b><code class="inline"><span class="w">Thread::Queue</span></code>
</b>
<p>Upgraded from version 2.00 to 2.11.</p>
</li>
<li><a name="Thread%3a%3aSemaphore"></a><b><code class="inline"><span class="w">Thread::Semaphore</span></code>
</b>
<p>Upgraded from version 2.01 to 2.09.</p>
</li>
<li><a name="Tie%3a%3aRefHash"></a><b><code class="inline"><span class="w">Tie::RefHash</span></code>
</b>
<p>Upgraded from version 1.37 to 1.38.</p>
</li>
<li><a name="Time%3a%3aHiRes"></a><b><code class="inline"><span class="w">Time::HiRes</span></code>
</b>
<p>Upgraded from version 1.9711 to 1.9719.</p>
</li>
<li><a name="Time%3a%3aLocal"></a><b><code class="inline"><span class="w">Time::Local</span></code>
</b>
<p>Upgraded from version 1.18 to 1.1901_01.</p>
</li>
<li><a name="Time%3a%3aPiece"></a><b><code class="inline"><span class="w">Time::Piece</span></code>
</b>
<p>Upgraded from version 1.12 to 1.15.</p>
</li>
<li><a name="Unicode%3a%3aCollate"></a><b><code class="inline"><span class="w">Unicode::Collate</span></code>
</b>
<p>Upgraded from version 0.52 to 0.52_01.</p>
</li>
<li><a name="Unicode%3a%3aNormalize"></a><b><code class="inline"><span class="w">Unicode::Normalize</span></code>
</b>
<p>Upgraded from version 1.02 to 1.03.</p>
</li>
<li><a name="Win32"></a><b><code class="inline"><span class="w">Win32</span></code>
</b>
<p>Upgraded from version 0.34 to 0.39.</p>
</li>
<li><a name="Win32API%3a%3aFile"></a><b><code class="inline"><span class="w">Win32API::File</span></code>
</b>
<p>Upgraded from version 0.1001_01 to 0.1101.</p>
</li>
<li><a name="XSLoader"></a><b><code class="inline"><span class="w">XSLoader</span></code>
</b>
<p>Upgraded from version 0.08 to 0.10.</p>
</li>
</ul>
<a name="Removed-Modules-and-Pragmata"></a><h2>Removed Modules and Pragmata</h2>
<ul>
<li><a name="attrs"></a><b><code class="inline"><span class="w">attrs</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 1.02.</p>
</li>
<li><a name="CPAN%3a%3aAPI%3a%3aHOWTO"></a><b><code class="inline"><span class="w">CPAN::API::HOWTO</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 'undef'.</p>
</li>
<li><a name="CPAN%3a%3aDeferedCode"></a><b><code class="inline"><span class="w">CPAN::DeferedCode</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 5.50.</p>
</li>
<li><a name="CPANPLUS%3a%3ainc"></a><b><code class="inline"><span class="w">CPANPLUS::inc</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 'undef'.</p>
</li>
<li><a name="DCLsym"></a><b><code class="inline"><span class="w">DCLsym</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 1.03.</p>
</li>
<li><a name="ExtUtils%3a%3aMakeMaker%3a%3abytes"></a><b><code class="inline"><span class="w">ExtUtils::MakeMaker::bytes</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 6.42.</p>
</li>
<li><a name="ExtUtils%3a%3aMakeMaker%3a%3avmsish"></a><b><code class="inline"><span class="w">ExtUtils::MakeMaker::vmsish</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 6.42.</p>
</li>
<li><a name="Stdio"></a><b><code class="inline"><span class="w">Stdio</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 2.3.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aAssert"></a><b><code class="inline"><span class="w">Test::Harness::Assert</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.02.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aIterator"></a><b><code class="inline"><span class="w">Test::Harness::Iterator</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.02.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aPoint"></a><b><code class="inline"><span class="w">Test::Harness::Point</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.01.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aResults"></a><b><code class="inline"><span class="w">Test::Harness::Results</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.01.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aStraps"></a><b><code class="inline"><span class="w">Test::Harness::Straps</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.26_01.</p>
</li>
<li><a name="Test%3a%3aHarness%3a%3aUtil"></a><b><code class="inline"><span class="w">Test::Harness::Util</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 0.01.</p>
</li>
<li><a name="XSSymSet"></a><b><code class="inline"><span class="w">XSSymSet</span></code>
</b>
<p>Removed from the Perl core.  Prior version was 1.1.</p>
</li>
</ul>
<a name="Deprecated-Modules-and-Pragmata"></a><h2>Deprecated Modules and Pragmata</h2>
<p>See <a href="#Deprecated-Modules">Deprecated Modules</a> above.</p>
<a name="Documentation"></a><h1>Documentation</h1>
<a name="New-Documentation"></a><h2>New Documentation</h2>
<ul>
<li>
<p><a href="perlhaiku.html">perlhaiku</a> contains instructions on how to build perl for the Haiku
platform.</p>
</li>
<li>
<p><a href="perlmroapi.html">perlmroapi</a> describes the new interface for pluggable Method Resolution
Orders.</p>
</li>
<li>
<p><a href="perlperf.html">perlperf</a>, by Richard Foley, provides an introduction to the use of
performance and optimization techniques which can be used with particular
reference to perl programs.</p>
</li>
<li>
<p><a href="perlrepository.html">perlrepository</a> describes how to access the perl source using the <i>git</i>
version control system.</p>
</li>
<li>
<p><a href="perlpolicy.html">perlpolicy</a> extends the "Social contract about contributed modules" into
the beginnings of a document on Perl porting policies.</p>
</li>
</ul>
<a name="Changes-to-Existing-Documentation"></a><h2>Changes to Existing Documentation</h2>
<ul>
<li>
<p>The various large <i>Changes*</i> files (which listed every change made
to perl over the last 18 years) have been removed, and replaced by a
small file, also called <i>Changes</i>, which just explains how that same
information may be extracted from the git version control system.</p>
</li>
<li>
<p><i>Porting/patching.pod</i> has been deleted, as it mainly described
interacting with the old Perforce-based repository, which is now obsolete.
Information still relevant has been moved to <a href="perlrepository.html">perlrepository</a>.</p>
</li>
<li>
<p>The syntax <code class="inline">unless (EXPR) BLOCK else BLOCK</code> is now documented as valid,
as is the syntax <code class="inline">unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
BLOCK</code>, although actually using the latter may not be the best idea for
the readability of your source code.</p>
</li>
<li>
<p>Documented -X overloading.</p>
</li>
<li>
<p>Documented that <code class="inline">when<span class="s">(</span><span class="s">)</span></code>
 treats specially most of the filetest operators</p>
</li>
<li>
<p>Documented <code class="inline">when</code>
 as a syntax modifier.</p>
</li>
<li>
<p>Eliminated "Old Perl threads tutorial", which described 5005 threads.</p>
<p><i>pod/perlthrtut.pod</i> is the same material reworked for ithreads.</p>
</li>
<li>
<p>Correct previous documentation: v-strings are not deprecated</p>
<p>With version objects, we need them to use MODULE VERSION syntax. This
patch removes the deprecation notice.</p>
</li>
<li>
<p>Security contact information is now part of <a href="perlsec.html">perlsec</a>.</p>
</li>
<li>
<p>A significant fraction of the core documentation has been updated to
clarify the behavior of Perl's Unicode handling.</p>
<p>Much of the remaining core documentation has been reviewed and edited
for clarity, consistent use of language, and to fix the spelling of Tom
Christiansen's name.</p>
</li>
<li>
<p>The Pod specification (<a href="perlpodspec.html">perlpodspec</a>) has been updated to bring the
specification in line with modern usage already supported by most Pod
systems. A parameter string may now follow the format name in a
"begin/end" region. Links to URIs with a text description are now
allowed. The usage of <code class="inline"><span class="w">L</span><span class="q">&lt;&quot;section&quot;&gt;</span></code>
 has been marked as
deprecated.</p>
</li>
<li>
<p><a href="if.html">if.pm</a> has been documented in <a href="functions/use.html">use</a> as a means to get
conditional loading of modules despite the implicit BEGIN block around
<code class="inline"><a class="l_k" href="functions/use.html">use</a></code>.</p>
</li>
<li>
<p>The documentation for <code class="inline"><span class="i">$1</span></code>
 in perlvar.pod has been clarified.</p>
</li>
<li>
<p><code class="inline">\N{U+<i>code point</i>}</code> is now documented.</p>
</li>
</ul>
<a name="Selected-Performance-Enhancements"></a><h1>Selected Performance Enhancements</h1>
<ul>
<li>
<p>A new internal cache means that <code class="inline"><span class="i">isa</span><span class="s">(</span><span class="s">)</span></code>
 will often be faster.</p>
</li>
<li>
<p>The implementation of <code class="inline"><span class="w">C3</span></code>
 Method Resolution Order has been
optimised - linearisation for classes with single inheritance is 40%
faster. Performance for multiple inheritance is unchanged.</p>
</li>
<li>
<p>Under <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
, the locale-relevant information is now cached on
read-only values, such as the list returned by <code class="inline"><a class="l_k" href="functions/keys.html">keys</a> <span class="i">%hash</span></code>
. This makes
operations such as <code class="inline"><a class="l_k" href="functions/sort.html">sort</a> <a class="l_k" href="functions/keys.html">keys</a> <span class="i">%hash</span></code>
 in the scope of <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>

much faster.</p>
</li>
<li>
<p>Empty <code class="inline">DESTROY</code>
 methods are no longer called.</p>
</li>
<li>
<p><code class="inline"><span class="i">Perl_sv_utf8_upgrade</span><span class="s">(</span><span class="s">)</span></code>
 is now faster.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/keys.html">keys</a></code> on empty hash is now faster.</p>
</li>
<li>
<p><code class="inline">if <span class="s">(</span><span class="i">%foo</span><span class="s">)</span></code>
 has been optimized to be faster than <code class="inline">if <span class="s">(</span><a class="l_k" href="functions/keys.html">keys</a> <span class="i">%foo</span><span class="s">)</span></code>
.</p>
</li>
<li>
<p>The string repetition operator (<code class="inline"><span class="i">$str</span> x <span class="i">$num</span></code>
) is now several times
faster when <code class="inline"><span class="i">$str</span></code>
 has length one or <code class="inline"><span class="i">$num</span></code>
 is large.</p>
</li>
<li>
<p>Reversing an array to itself (as in <code class="inline"><span class="i">@a</span> = <a class="l_k" href="functions/reverse.html">reverse</a> <span class="i">@a</span></code>
) in void context
now happens in-place and is several orders of magnitude faster than
it used to be. It will also preserve non-existent elements whenever
possible, i.e. for non magical arrays or tied arrays with <code class="inline"><span class="w">EXISTS</span></code>

and <code class="inline"><span class="w">DELETE</span></code>
 methods.</p>
</li>
</ul>
<a name="Installation-and-Configuration-Improvements"></a><h1>Installation and Configuration Improvements</h1>
<ul>
<li>
<p><a href="perlapi.html">perlapi</a>, <a href="perlintern.html">perlintern</a>, <a href="perlmodlib.html">perlmodlib</a> and <a href="http://search.cpan.org/perldoc/perltoc">perltoc</a> are now all
generated at build time, rather than being shipped as part of the release.</p>
</li>
<li>
<p>If <code class="inline"><span class="w">vendorlib</span></code>
 and <code class="inline"><span class="w">vendorarch</span></code>
 are the same, then they are only added
to <code class="inline"><span class="i">@INC</span></code>
 once.</p>
</li>
<li>
<p><code class="inline"><span class="i">$Config</span>{<span class="w">usedevel</span>}</code>
 and the C-level <code class="inline"><span class="w">PERL_USE_DEVEL</span></code>
 are now defined if
perl is built with  <code class="inline">-<span class="w">Dusedevel</span></code>
.</p>
</li>
<li>
<p><i>Configure</i> will enable use of <code class="inline">-<span class="w">fstack</span>-<span class="w">protector</span></code>
, to provide protection
against stack-smashing attacks, if the compiler supports it.</p>
</li>
<li>
<p><i>Configure</i> will now determine the correct prototypes for re-entrant
functions and for <code class="inline"><span class="w">gconvert</span></code>
 if you are using a C++ compiler rather
than a C compiler.</p>
</li>
<li>
<p>On Unix, if you build from a tree containing a git repository, the
configuration process will note the commit hash you have checked out, for
display in the output of <code class="inline"><span class="w">perl</span> -<span class="w">v</span></code>
 and <code class="inline"><span class="w">perl</span> -<span class="w">V</span></code>
. Unpushed local commits
are automatically added to the list of local patches displayed by
<code class="inline"><span class="w">perl</span> -<span class="w">V</span></code>
.</p>
</li>
<li>
<p>Perl now supports SystemTap's <code class="inline"><span class="w">dtrace</span></code>
 compatibility layer and an
issue with linking <code class="inline"><span class="w">miniperl</span></code>
 has been fixed in the process.</p>
</li>
<li>
<p>perldoc now uses <code class="inline"><span class="w">less</span> -R</code>
 instead of <code class="inline"><span class="w">less</span></code>
 for improved behaviour
in the face of <code class="inline"><span class="w">groff</span></code>
's new usage of ANSI escape codes.</p>
</li>
<li>
<p><code class="inline"><span class="w">perl</span> -<span class="w">V</span></code>
 now reports use of the compile-time options <code class="inline"><span class="w">USE_PERL_ATOF</span></code>
 and
<code class="inline"><span class="w">USE_ATTRIBUTES_FOR_PERLIO</span></code>
.</p>
</li>
<li>
<p>As part of the flattening of <i>ext</i>, all extensions on all platforms are
built by <i>make_ext.pl</i>. This replaces the Unix-specific
<i>ext/util/make_ext</i>, VMS-specific <i>make_ext.com</i> and Win32-specific
<i>win32/buildext.pl</i>.</p>
</li>
</ul>
<a name="Internal-Changes"></a><h1>Internal Changes</h1>
<p>Each release of Perl sees numerous internal changes which shouldn't
affect day to day usage but may still be notable for developers working
with Perl's source code.</p>
<ul>
<li>
<p>The J.R.R. Tolkien quotes at the head of C source file have been checked
and proper citations added, thanks to a patch from Tom Christiansen.</p>
</li>
<li>
<p>The internal structure of the dual-life modules traditionally found in
the <i>lib/</i> and <i>ext/</i> directories in the perl source has changed
significantly. Where possible, dual-lifed modules have been extracted
from <i>lib/</i> and <i>ext/</i>.</p>
<p>Dual-lifed modules maintained by Perl's developers as part of the Perl
core now live in <i>dist/</i>.  Dual-lifed modules maintained primarily on
CPAN now live in <i>cpan/</i>.  When reporting a bug in a module located
under <i>cpan/</i>, please send your bug report directly to the module's
bug tracker or author, rather than Perl's bug tracker.</p>
</li>
<li>
<p><code class="inline">\<span class="i">N</span><span class="s">{</span>...<span class="s">}</span></code>
 now compiles better, always forces UTF-8 internal representation</p>
<p>Perl's developers have fixed several problems with the recognition of
<code class="inline">\<span class="i">N</span><span class="s">{</span>...<span class="s">}</span></code>
 constructs.  As part of this, perl will store any scalar
or regex containing <code class="inline">\N{<i>name</i>}</code> or <code class="inline">\N{U+<i>code point</i>}</code> in its
definition in UTF-8 format. (This was true previously for all occurrences
of <code class="inline">\N{<i>name</i>}</code> that did not use a custom translator, but now it's
always true.)</p>
</li>
<li>
<p>Perl_magic_setmglob now knows about globs, fixing RT #71254.</p>
</li>
<li>
<p><code class="inline"><span class="w">SVt_RV</span></code>
 no longer exists. RVs are now stored in IVs.</p>
</li>
<li>
<p><code class="inline"><span class="i">Perl_vcroak</span><span class="s">(</span><span class="s">)</span></code>
 now accepts a null first argument. In addition, a full
audit was made of the "not NULL" compiler annotations, and those for
several other internal functions were corrected.</p>
</li>
<li>
<p>New macros <code class="inline"><span class="w">dSAVEDERRNO</span></code>
, <code class="inline"><span class="w">dSAVE_ERRNO</span></code>
, <code class="inline"><span class="w">SAVE_ERRNO</span></code>
, <code class="inline"><span class="w">RESTORE_ERRNO</span></code>

have been added to formalise the temporary saving of the <code class="inline"><span class="w">errno</span></code>

variable.</p>
</li>
<li>
<p>The function <code class="inline"><span class="w">Perl_sv_insert_flags</span></code>
 has been added to augment
<code class="inline"><span class="w">Perl_sv_insert</span></code>
.</p>
</li>
<li>
<p>The function <code class="inline"><span class="i">Perl_newSV_type</span><span class="s">(</span><span class="w">type</span><span class="s">)</span></code>
 has been added, equivalent to
<code class="inline"><span class="i">Perl_newSV</span><span class="s">(</span><span class="s">)</span></code>
 followed by <code class="inline"><span class="i">Perl_sv_upgrade</span><span class="s">(</span><span class="w">type</span><span class="s">)</span></code>
.</p>
</li>
<li>
<p>The function <code class="inline"><span class="i">Perl_newSVpvn_flags</span><span class="s">(</span><span class="s">)</span></code>
 has been added, equivalent to
<code class="inline"><span class="i">Perl_newSVpvn</span><span class="s">(</span><span class="s">)</span></code>
 and then performing the action relevant to the flag.</p>
<p>Two flag bits are currently supported.</p>
<ul>
<li>
<p><code class="inline"><span class="w">SVf_UTF8</span></code>
 will call <code class="inline"><span class="i">SvUTF8_on</span><span class="s">(</span><span class="s">)</span></code>
 for you. (Note that this does
not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
<code class="inline"><span class="i">newSVpvn_utf8</span><span class="s">(</span><span class="s">)</span></code>
 is available for this.</p>
</li>
<li>
<p><code class="inline"><span class="w">SVs_TEMP</span></code>
 now calls <code class="inline"><span class="i">Perl_sv_2mortal</span><span class="s">(</span><span class="s">)</span></code>
 on the new SV.</p>
</li>
</ul>
<p>There is also a wrapper that takes constant strings, <code class="inline"><span class="i">newSVpvs_flags</span><span class="s">(</span><span class="s">)</span></code>
.</p>
</li>
<li>
<p>The function <code class="inline"><span class="w">Perl_croak_xs_usage</span></code>
 has been added as a wrapper to
<code class="inline"><span class="w">Perl_croak</span></code>
.</p>
</li>
<li>
<p>Perl now exports the functions <code class="inline"><span class="w">PerlIO_find_layer</span></code>
 and <code class="inline"><span class="w">PerlIO_list_alloc</span></code>
.</p>
</li>
<li>
<p><code class="inline"><span class="w">PL_na</span></code>
 has been exterminated from the core code, replaced by local
STRLEN temporaries, or <code class="inline"><span class="i">*_nolen</span><span class="s">(</span><span class="s">)</span></code>
 calls. Either approach is faster than
<code class="inline"><span class="w">PL_na</span></code>
, which is a pointer dereference into the interpreter structure
under ithreads, and a global variable otherwise.</p>
</li>
<li>
<p><code class="inline"><span class="i">Perl_mg_free</span><span class="s">(</span><span class="s">)</span></code>
 used to leave freed memory accessible via <code class="inline"><span class="i">SvMAGIC</span><span class="s">(</span><span class="s">)</span></code>

on the scalar. It now updates the linked list to remove each piece of
magic as it is freed.</p>
</li>
<li>
<p>Under ithreads, the regex in <code class="inline"><span class="w">PL_reg_curpm</span></code>
 is now reference
counted. This eliminates a lot of hackish workarounds to cope with it
not being reference counted.</p>
</li>
<li>
<p><code class="inline"><span class="i">Perl_mg_magical</span><span class="s">(</span><span class="s">)</span></code>
 would sometimes incorrectly turn on <code class="inline"><span class="i">SvRMAGICAL</span><span class="s">(</span><span class="s">)</span></code>
.
This has been fixed.</p>
</li>
<li>
<p>The <i>public</i> IV and NV flags are now not set if the string value has
trailing "garbage". This behaviour is consistent with not setting the
public IV or NV flags if the value is out of range for the type.</p>
</li>
<li>
<p>Uses of <code class="inline"><span class="w">Nullav</span></code>
, <code class="inline"><span class="w">Nullcv</span></code>
, <code class="inline"><span class="w">Nullhv</span></code>
, <code class="inline"><span class="w">Nullop</span></code>
, <code class="inline"><span class="w">Nullsv</span></code>
 etc have
been replaced by <code class="inline"><span class="w">NULL</span></code>
 in the core code, and non-dual-life modules,
as <code class="inline"><span class="w">NULL</span></code>
 is clearer to those unfamiliar with the core code.</p>
</li>
<li>
<p>A macro <code class="inline"><span class="i">MUTABLE_PTR</span><span class="s">(</span><span class="w">p</span><span class="s">)</span></code>
 has been added, which on (non-pedantic) gcc will
not cast away <code class="inline"><span class="w">const</span></code>
, returning a <code class="inline"><span class="w">void</span> *</code>
. Macros <code class="inline"><span class="i">MUTABLE_SV</span><span class="s">(</span><span class="w">av</span><span class="s">)</span></code>
,
<code class="inline"><span class="i">MUTABLE_SV</span><span class="s">(</span><span class="w">cv</span><span class="s">)</span></code>
 etc build on this, casting to <code class="inline"><span class="w">AV</span> *</code>
 etc without
casting away <code class="inline"><span class="w">const</span></code>
. This allows proper compile-time auditing of
<code class="inline"><span class="w">const</span></code>
 correctness in the core, and helped picked up some errors
(now fixed).</p>
</li>
<li>
<p>Macros <code class="inline"><span class="i">mPUSHs</span><span class="s">(</span><span class="s">)</span></code>
 and <code class="inline"><span class="i">mXPUSHs</span><span class="s">(</span><span class="s">)</span></code>
 have been added, for pushing SVs on the
stack and mortalizing them.</p>
</li>
<li>
<p>Use of the private structure <code class="inline"><span class="w">mro_meta</span></code>
 has changed slightly. Nothing
outside the core should be accessing this directly anyway.</p>
</li>
<li>
<p>A new tool, <i>Porting/expand-macro.pl</i> has been added, that allows you
to view how a C preprocessor macro would be expanded when compiled.
This is handy when trying to decode the macro hell that is the perl
guts.</p>
</li>
</ul>
<a name="Testing"></a><h1>Testing</h1>
<a name="Testing-improvements"></a><h2>Testing improvements</h2>
<ul>
<li><a name="Parallel-tests"></a><b>Parallel tests</b>
<p>The core distribution can now run its regression tests in parallel on
Unix-like platforms. Instead of running <code class="inline"><span class="w">make</span> <span class="w">test</span></code>
, set <code class="inline"><span class="w">TEST_JOBS</span></code>
 in
your environment to the number of tests to run in parallel, and run
<code class="inline"><span class="w">make</span> <span class="w">test_harness</span></code>
. On a Bourne-like shell, this can be done as</p>
<pre class="verbatim"><ol><li>    TEST_JOBS=3 make test_harness  # Run 3 tests in parallel</li></ol></pre><p>An environment variable is used, rather than parallel make itself, because
<a href="TAP/Harness.html">TAP::Harness</a> needs to be able to schedule individual non-conflicting test
scripts itself, and there is no standard interface to <code class="inline"><span class="w">make</span></code>
 utilities to
interact with their job schedulers.</p>
<p>Note that currently some test scripts may fail when run in parallel (most
notably <code class="inline"><span class="w">ext</span>/<span class="w">IO</span>/<span class="w">t</span>/<span class="w">io_dir</span>.<span class="w">t</span></code>
). If necessary run just the failing scripts
again sequentially and see if the failures go away.</p>
</li>
<li><a name="Test-harness-flexibility"></a><b>Test harness flexibility</b>
<p>It's now possible to override <code class="inline"><span class="w">PERL5OPT</span></code>
 and friends in <i>t/TEST</i></p>
</li>
<li><a name="Test-watchdog"></a><b>Test watchdog</b>
<p>Several tests that have the potential to hang forever if they fail now
incorporate a "watchdog" functionality that will kill them after a timeout,
which helps ensure that <code class="inline"><span class="w">make</span> <span class="w">test</span></code>
 and <code class="inline"><span class="w">make</span> <span class="w">test_harness</span></code>
 run to
completion automatically.</p>
</li>
</ul>
<a name="New-Tests"></a><h2>New Tests</h2>
<p>Perl's developers have added a number of new tests to the core.
In addition to the items listed below, many modules updated from CPAN
incorporate new tests.</p>
<ul>
<li>
<p>Significant cleanups to core tests to ensure that language and
interpreter features are not used before they're tested.</p>
</li>
<li>
<p><code class="inline"><span class="w">make</span> <span class="w">test_porting</span></code>
 now runs a number of important pre-commit checks
which might be of use to anyone working on the Perl core.</p>
</li>
<li>
<p><i>t/porting/podcheck.t</i> automatically checks the well-formedness of
POD found in all .pl, .pm and .pod files in the <i>MANIFEST</i>, other than in
dual-lifed modules which are primarily maintained outside the Perl core.</p>
</li>
<li>
<p><i>t/porting/manifest.t</i> now tests that all files listed in MANIFEST
are present.</p>
</li>
<li>
<p><i>t/op/while_readdir.t</i> tests that a bare readdir in while loop sets $_.</p>
</li>
<li>
<p><i>t/comp/retainedlines.t</i> checks that the debugger can retain source
lines from <code class="inline"><a class="l_k" href="functions/eval.html">eval</a></code>.</p>
</li>
<li>
<p><i>t/io/perlio_fail.t</i> checks that bad layers fail.</p>
</li>
<li>
<p><i>t/io/perlio_leaks.t</i> checks that PerlIO layers are not leaking.</p>
</li>
<li>
<p><i>t/io/perlio_open.t</i> checks that certain special forms of open work.</p>
</li>
<li>
<p><i>t/io/perlio.t</i> includes general PerlIO tests.</p>
</li>
<li>
<p><i>t/io/pvbm.t</i> checks that there is no unexpected interaction between
the internal types <code class="inline"><span class="w">PVBM</span></code>
 and <code class="inline"><span class="w">PVGV</span></code>
.</p>
</li>
<li>
<p><i>t/mro/package_aliases.t</i> checks that mro works properly in the presence
of aliased packages.</p>
</li>
<li>
<p><i>t/op/dbm.t</i> tests <code class="inline"><a class="l_k" href="functions/dbmopen.html">dbmopen</a></code> and <code class="inline"><a class="l_k" href="functions/dbmclose.html">dbmclose</a></code>.</p>
</li>
<li>
<p><i>t/op/index_thr.t</i> tests the interaction of <code class="inline"><a class="l_k" href="functions/index.html">index</a></code> and threads.</p>
</li>
<li>
<p><i>t/op/pat_thr.t</i> tests the interaction of esoteric patterns and threads.</p>
</li>
<li>
<p><i>t/op/qr_gc.t</i> tests that <code class="inline"><a class="l_k" href="functions/qr.html">qr</a></code> doesn't leak.</p>
</li>
<li>
<p><i>t/op/reg_email_thr.t</i> tests the interaction of regex recursion and threads.</p>
</li>
<li>
<p><i>t/op/regexp_qr_embed_thr.t</i> tests the interaction of patterns with
embedded <code class="inline"><a class="l_k" href="functions/qr.html">qr//</a></code> and threads.</p>
</li>
<li>
<p><i>t/op/regexp_unicode_prop.t</i> tests Unicode properties in regular
expressions.</p>
</li>
<li>
<p><i>t/op/regexp_unicode_prop_thr.t</i> tests the interaction of Unicode
properties and threads.</p>
</li>
<li>
<p><i>t/op/reg_nc_tie.t</i> tests the tied methods of <code class="inline"><span class="w">Tie::Hash::NamedCapture</span></code>
.</p>
</li>
<li>
<p><i>t/op/reg_posixcc.t</i> checks that POSIX character classes behave
consistently.</p>
</li>
<li>
<p><i>t/op/re.t</i> checks that exportable <code class="inline"><span class="w">re</span></code>
 functions in <i>universal.c</i> work.</p>
</li>
<li>
<p><i>t/op/setpgrpstack.t</i> checks that <code class="inline"><a class="l_k" href="functions/setpgrp.html">setpgrp</a></code> works.</p>
</li>
<li>
<p><i>t/op/substr_thr.t</i> tests the interaction of <code class="inline"><a class="l_k" href="functions/substr.html">substr</a></code> and threads.</p>
</li>
<li>
<p><i>t/op/upgrade.t</i> checks that upgrading and assigning scalars works.</p>
</li>
<li>
<p><i>t/uni/lex_utf8.t</i> checks that Unicode in the lexer works.</p>
</li>
<li>
<p><i>t/uni/tie.t</i> checks that Unicode and <code class="inline"><a class="l_k" href="functions/tie.html">tie</a></code> work.</p>
</li>
<li>
<p><i>t/comp/final_line_num.t</i> tests whether line numbers are correct at EOF</p>
</li>
<li>
<p><i>t/comp/form_scope.t</i> tests format scoping.</p>
</li>
<li>
<p><i>t/comp/line_debug.t</i> tests whether <code class="inline"><span class="i">@</span>{<span class="q">&quot;_&lt;$file&quot;</span>}</code>
 works.</p>
</li>
<li>
<p><i>t/op/filetest_t.t</i> tests if -t file test works.</p>
</li>
<li>
<p><i>t/op/qr.t</i> tests <code class="inline"><a class="l_k" href="functions/qr.html">qr</a></code>.</p>
</li>
<li>
<p><i>t/op/utf8cache.t</i> tests malfunctions of the utf8 cache.</p>
</li>
<li>
<p><i>t/re/uniprops.t</i> test unicodes <code class="inline">\<span class="w">p</span><span class="s">{</span><span class="s">}</span></code>
 regex constructs.</p>
</li>
<li>
<p><i>t/op/filehandle.t</i> tests some suitably portable filetest operators
to check that they work as expected, particularly in the light of some
internal changes made in how filehandles are blessed.</p>
</li>
<li>
<p><i>t/op/time_loop.t</i> tests that unix times greater than <code class="inline"><span class="n">2</span>**<span class="n">63</span></code>
, which
can now be handed to <code class="inline"><a class="l_k" href="functions/gmtime.html">gmtime</a></code> and <code class="inline"><a class="l_k" href="functions/localtime.html">localtime</a></code>, do not cause an internal
overflow or an excessively long loop.</p>
</li>
</ul>
<a name="New-or-Changed-Diagnostics"></a><h1>New or Changed Diagnostics</h1>
<a name="New-Diagnostics"></a><h2>New Diagnostics</h2>
<ul>
<li>
<p>SV allocation tracing has been added to the diagnostics enabled by <code class="inline">-<span class="w">Dm</span></code>
.
The tracing can alternatively output via the <code class="inline"><span class="w">PERL_MEM_LOG</span></code>
 mechanism, if
that was enabled when the <i>perl</i> binary was compiled.</p>
</li>
<li>
<p>Smartmatch resolution tracing has been added as a new diagnostic. Use
<code class="inline">-<span class="w">DM</span></code>
 to enable it.</p>
</li>
<li>
<p>A new debugging flag <code class="inline">-<span class="w">DB</span></code>
 now dumps subroutine definitions, leaving
<code class="inline">-<span class="w">Dx</span></code>
 for its original purpose of dumping syntax trees.</p>
</li>
<li>
<p>Perl 5.12 provides a number of new diagnostic messages to help you write
better code.  See <a href="perldiag.html">perldiag</a> for details of these new messages.</p>
<ul>
<li>
<p><code class="inline"><span class="w">Bad</span> <span class="w">plugin</span> <span class="w">affecting</span> <span class="w">keyword</span> <span class="q">&#39;%s&#39;</span></code>
</p>
</li>
<li>
<p><code class="inline">gmtime(%.0f) too large</code></p>
</li>
<li>
<p><code class="inline">Lexing code attempted to stuff non-Latin-1 character into Latin-1 input</code></p>
</li>
<li>
<p><code class="inline"><span class="w">Lexing</span> <span class="w">code</span> <span class="w">internal</span> <span class="w">error</span> <span class="s">(</span><span class="i">%s</span><span class="s">)</span></code>
</p>
</li>
<li>
<p><code class="inline">localtime(%.0f) too large</code></p>
</li>
<li>
<p><code class="inline"><span class="w">Overloaded</span> <span class="w">dereference</span> <span class="w">did</span> not <a class="l_k" href="functions/return.html">return</a> <span class="w">a</span> <span class="w">reference</span></code>
</p>
</li>
<li>
<p><code class="inline"><span class="w">Overloaded</span> <span class="q">qr did</span> not <a class="l_k" href="functions/return.html">return</a> <span class="w">a</span> <span class="w">REGEXP</span></code>
</p>
</li>
<li>
<p><code class="inline">Perl_pmflag() is deprecated, and will be removed from the XS API</code></p>
</li>
<li>
<p><code class="inline"><span class="w">lvalue</span> <span class="w">attribute</span> <span class="w">ignored</span> <span class="w">after</span> <span class="w">the</span> <span class="w">subroutine</span> <span class="w">has</span> <span class="w">been</span> <a class="l_k" href="functions/defined.html">defined</a></code>
</p>
<p>This new warning is issued when one attempts to mark a subroutine as
lvalue after it has been defined.</p>
</li>
<li>
<p>Perl now warns you if <code class="inline">++</code>
 or <code class="inline">--</code>
 are unable to change the value
because it's beyond the limit of representation.</p>
<p>This uses a new warnings category: "imprecision".</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/lc.html">lc</a></code>, <code class="inline"><a class="l_k" href="functions/uc.html">uc</a></code>, <code class="inline"><a class="l_k" href="functions/lcfirst.html">lcfirst</a></code>, and <code class="inline"><a class="l_k" href="functions/ucfirst.html">ucfirst</a></code> warn when passed undef.</p>
</li>
<li>
<p><code class="inline"><span class="w">Show</span> <span class="w">constant</span> <span class="w">in</span> <span class="q">&quot;Useless use of a constant in void context&quot;</span></code>
</p>
</li>
<li>
<p><code class="inline"><span class="w">Prototype</span> <span class="w">after</span> <span class="q">&#39;%s&#39;</span></code>
</p>
</li>
<li>
<p><code class="inline"><span class="j">panic:</span> <span class="w">sv_chop</span> <span class="i">%s</span></code>
</p>
<p>This new fatal error occurs when the C routine <code class="inline"><span class="i">Perl_sv_chop</span><span class="s">(</span><span class="s">)</span></code>
 was
passed a position that is not within the scalar's string buffer. This
could be caused by buggy XS code, and at this point recovery is not
possible.</p>
</li>
<li>
<p>The fatal error <code class="inline">Malformed UTF-8 returned by \N</code> is now produced if the
<code class="inline"><span class="w">charnames</span></code>
 handler returns malformed UTF-8.</p>
</li>
<li>
<p>If an unresolved named character or sequence was encountered when
compiling a regex pattern then the fatal error <code class="inline">\<span class="i">N</span><span class="s">{</span><span class="w">NAME</span><span class="s">}</span> <span class="w">must</span> <span class="w">be</span> <span class="w">resolved</span>
<span class="w">by</span> <span class="w">the</span> <span class="w">lexer</span></code>
 is now produced. This can happen, for example, when using a
single-quotish context like <code class="inline"><span class="i">$re</span> = <span class="q">&#39;\N{SPACE}&#39;</span><span class="sc">;</span> <span class="q">/$re/</span><span class="sc">;</span></code>
. See <a href="perldiag.html">perldiag</a>
for more examples of how the lexer can get bypassed.</p>
</li>
<li>
<p><code class="inline"><span class="w">Invalid</span> <span class="w">hexadecimal</span> <span class="w">number</span> <span class="w">in</span> \<span class="i">N</span><span class="s">{</span><span class="w">U</span>+...<span class="s">}</span></code>
 is a new fatal error
triggered when the character constant represented by <code class="inline">...</code>
 is not a
valid hexadecimal number.</p>
</li>
<li>
<p>The new meaning of <code class="inline">\<span class="w">N</span></code>
 as <code class="inline">[^\n]</code> is not valid in a bracketed character
class, just like <code class="inline">.</code> in a character class loses its special meaning,
and will cause the fatal error <code class="inline">\N in a character class must be a named
character: \N{...}</code>.</p>
</li>
<li>
<p>The rules on what is legal for the <code class="inline">...</code>
 in <code class="inline">\<span class="i">N</span><span class="s">{</span>...<span class="s">}</span></code>
 have been
tightened up so that unless the <code class="inline">...</code>
 begins with an alphabetic
character and continues with a combination of alphanumerics, dashes,
spaces, parentheses or colons then the warning <code class="inline">Deprecated character(s)
in \N{...} starting at '%s'</code> is now issued.</p>
</li>
<li>
<p>The warning <code class="inline"><span class="w">Using</span> <span class="w">just</span> <span class="w">the</span> <span class="w">first</span> <span class="w">characters</span> <span class="w">returned</span> <span class="w">by</span> \<span class="w">N</span><span class="s">{</span><span class="s">}</span></code>
 will
be issued if the <code class="inline"><span class="w">charnames</span></code>
 handler returns a sequence of characters
which exceeds the limit of the number of characters that can be used. The
message will indicate which characters were used and which were discarded.</p>
</li>
</ul>
</li>
</ul>
<a name="Changed-Diagnostics"></a><h2>Changed Diagnostics</h2>
<p>A number of existing diagnostic messages have been improved or corrected:</p>
<ul>
<li>
<p>A new warning category <code class="inline"><span class="w">illegalproto</span></code>
 allows finer-grained control of
warnings around function prototypes.</p>
<p>The two warnings:</p>
<ul>
<li><a name="Illegal-character-in-prototype-for-%25s-%3a-%25s"></a><b><code class="inline">Illegal character in prototype for %s : %s</code></b>
</li>
<li><a name="Prototype-after-'%25c'-for-%25s-%3a-%25s"></a><b><code class="inline">Prototype after '%c' for %s : %s</code></b>
</li>
</ul>
<p>have been moved from the <code class="inline"><span class="w">syntax</span></code>
 top-level warnings category into a new
first-level category, <code class="inline"><span class="w">illegalproto</span></code>
. These two warnings are currently
the only ones emitted during parsing of an invalid/illegal prototype,
so one can now use</p>
<pre class="verbatim"><ol><li>  <a class="l_k" href="functions/no.html">no</a> <span class="w">warnings</span> <span class="q">&#39;illegalproto&#39;</span><span class="sc">;</span></li></ol></pre><p>to suppress only those, but not other syntax-related warnings. Warnings
where prototypes are changed, ignored, or not met are still in the
<code class="inline"><a class="l_k" href="functions/prototype.html">prototype</a></code> category as before.</p>
</li>
<li>
<p><code class="inline"><span class="w">Deep</span> <span class="w">recursion</span> <span class="w">on</span> <span class="w">subroutine</span> <span class="q">&quot;%s&quot;</span></code>
</p>
<p>It is now possible to change the depth threshold for this warning from the
default of 100, by recompiling the <i>perl</i> binary, setting the C
pre-processor macro <code class="inline"><span class="w">PERL_SUB_DEPTH_WARN</span></code>
 to the desired value.</p>
</li>
<li>
<p><code class="inline"><span class="w">Illegal</span> <span class="w">character</span> <span class="w">in</span> <a class="l_k" href="functions/prototype.html">prototype</a></code>
 warning is now more precise
when reporting illegal characters after _</p>
</li>
<li>
<p>mro merging error messages are now very similar to those produced by
<a href="http://search.cpan.org/perldoc/Algorithm::C3">Algorithm::C3</a>.</p>
</li>
<li>
<p>Amelioration of the error message "Unrecognized character %s in column %d"</p>
<p>Changes the error message to "Unrecognized character %s; marked by &lt;--
HERE after %s&lt;-- HERE near column %d". This should make it a little
simpler to spot and correct the suspicious character.</p>
</li>
<li>
<p>Perl now explicitly points to <code class="inline"><span class="i">$.</span></code>
 when it causes an uninitialized
warning for ranges in scalar context.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/split.html">split</a></code> now warns when called in void context.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/printf.html">printf</a></code>-style functions called with too few arguments will now issue the
warning <code class="inline"><span class="q">&quot;Missing argument in %s&quot;</span></code>
 [perl #71000]</p>
</li>
<li>
<p>Perl now properly returns a syntax error instead of segfaulting
if <code class="inline"><a class="l_k" href="functions/each.html">each</a></code>, <code class="inline"><a class="l_k" href="functions/keys.html">keys</a></code>, or <code class="inline"><a class="l_k" href="functions/values.html">values</a></code> is used without an argument.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/tell.html">tell()</a></code> now fails properly if called without an argument and when no
previous file was read.</p>
<p><code class="inline"><a class="l_k" href="functions/tell.html">tell()</a></code> now returns <code class="inline"><span class="n">-1</span></code>
, and sets errno to <code class="inline"><span class="w">EBADF</span></code>
, thus restoring
the 5.8.x behaviour.</p>
</li>
<li>
<p><code class="inline"><span class="w">overload</span></code>
 no longer implicitly unsets fallback on repeated 'use
overload' lines.</p>
</li>
<li>
<p>POSIX::strftime() can now handle Unicode characters in the format string.</p>
</li>
<li>
<p>The <code class="inline"><span class="w">syntax</span></code>
 category was removed from 5 warnings that should only be in
<code class="inline"><span class="w">deprecated</span></code>
.</p>
</li>
<li>
<p>Three fatal <code class="inline"><a class="l_k" href="functions/pack.html">pack</a></code>/<code class="inline"><a class="l_k" href="functions/unpack.html">unpack</a></code> error messages have been normalized to
<code class="inline"><span class="j">panic:</span> <span class="i">%s</span></code>
</p>
</li>
<li>
<p><code class="inline"><span class="w">Unicode</span> <span class="w">character</span> <span class="w">is</span> <span class="w">illegal</span></code>
 has been rephrased to be more accurate</p>
<p>It now reads <code class="inline"><span class="w">Unicode</span> <span class="w">non</span>-<span class="w">character</span> <span class="w">is</span> <span class="w">illegal</span> <span class="w">in</span> <span class="w">interchange</span></code>
 and the
perldiag documentation has been expanded a bit.</p>
</li>
<li>
<p>Currently, all but the first of the several characters that the
<code class="inline"><span class="w">charnames</span></code>
 handler may return are discarded when used in a regular
expression pattern bracketed character class. If this happens then the
warning <code class="inline"><span class="w">Using</span> <span class="w">just</span> <span class="w">the</span> <span class="w">first</span> <span class="w">character</span> <span class="w">returned</span> <span class="w">by</span> \<span class="w">N</span><span class="s">{</span><span class="s">}</span> <span class="w">in</span> <span class="w">character</span>
<span class="w">class</span></code>
 will be issued.</p>
</li>
<li>
<p>The warning <code class="inline"><span class="w">Missing</span> <span class="w">right</span> <span class="w">brace</span> <span class="w">on</span> \<span class="w">N</span><span class="s">{</span><span class="s">}</span> or <span class="w">unescaped</span> <span class="w">left</span> <span class="w">brace</span> <span class="w">after</span>
\<span class="w">N</span>.  <span class="w">Assuming</span> <span class="w">the</span> <span class="w">latter</span></code>
 will be issued if Perl encounters a <code class="inline">\N{</code>
but doesn't find a matching <code class="inline">}</code>. In this case Perl doesn't know if it
was mistakenly omitted, or if "match non-newline" followed by "match
a <code class="inline">{</code>" was desired.  It assumes the latter because that is actually a
valid interpretation as written, unlike the other case.  If you meant
the former, you need to add the matching right brace.  If you did mean
the latter, you can silence this warning by writing instead <code class="inline">\N\{</code>.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/gmtime.html">gmtime</a></code> and <code class="inline"><a class="l_k" href="functions/localtime.html">localtime</a></code> called with numbers smaller than they can
reliably handle will now issue the warnings <code class="inline">gmtime(%.0f) too small</code>
and <code class="inline">localtime(%.0f) too small</code>.</p>
</li>
</ul>
<p>The following diagnostic messages have been removed:</p>
<ul>
<li>
<p><code class="inline">Runaway format</code></p>
</li>
<li>
<p><code class="inline"><span class="w">Can&#39;t</span> <span class="w">locate</span> <a class="l_k" href="functions/package.html">package</a> <span class="i">%s</span> for <span class="w">the</span> <span class="w">parents</span> <span class="w">of</span> <span class="i">%s</span></code>
</p>
<p>In general this warning it only got produced in
conjunction with other warnings, and removing it allowed an ISA lookup
optimisation to be added.</p>
</li>
<li>
<p><code class="inline">v-string in use/require is non-portable</code></p>
</li>
</ul>
<a name="Utility-Changes"></a><h1>Utility Changes</h1>
<ul>
<li>
<p><i>h2ph</i> now looks in <code class="inline"><span class="w">include</span>-<span class="w">fixed</span></code>
 too, which is a recent addition
to gcc's search path.</p>
</li>
<li>
<p><i>h2xs</i> no longer incorrectly treats enum values like macros.
It also now handles C++ style comments (<code class="inline"><span class="q">//</span></code>
) properly in enums.</p>
</li>
<li>
<p><i>perl5db.pl</i> now supports <code class="inline"><span class="w">LVALUE</span></code>
 subroutines.  Additionally, the
debugger now correctly handles proxy constant subroutines, and
subroutine stubs.</p>
</li>
<li>
<p><i>perlbug</i> now uses <code class="inline"><span class="i">%Module::CoreList::bug_tracker</span></code>
 to print out
upstream bug tracker URLs.  If a user identifies a particular module
as the topic of their bug report and we're able to divine the URL for
its upstream bug tracker, perlbug now provide a message to the user
explaining that the core copies the CPAN version directly, and provide
the URL for reporting the bug directly to the upstream author.</p>
<p><i>perlbug</i> no longer reports "Message sent" when it hasn't actually sent
the message</p>
</li>
<li>
<p><i>perlthanks</i> is a new utility for sending non-bug-reports to the
authors and maintainers of Perl. Getting nothing but bug reports can
become a bit demoralising. If Perl 5.12 works well for you, please try
out <i>perlthanks</i>. It will make the developers smile.</p>
</li>
<li>
<p>Perl's developers have fixed bugs in <i>a2p</i> having to do with the
<code class="inline"><span class="i">match</span><span class="s">(</span><span class="s">)</span></code>
 operator in list context.  Additionally, <i>a2p</i> no longer
generates code that uses the <code class="inline"><span class="i">$[</span></code>
 variable.</p>
</li>
</ul>
<a name="Selected-Bug-Fixes"></a><h1>Selected Bug Fixes</h1>
<ul>
<li>
<p>U+0FFFF is now a legal character in regular expressions.</p>
</li>
<li>
<p>pp_qr now always returns a new regexp SV. Resolves RT #69852.</p>
<p>Instead of returning a(nother) reference to the (pre-compiled) regexp
in the optree, use reg_temp_copy() to create a copy of it, and return a
reference to that. This resolves issues about Regexp::DESTROY not being
called in a timely fashion (the original bug tracked by RT #69852), as
well as bugs related to blessing regexps, and of assigning to regexps,
as described in correspondence added to the ticket.</p>
<p>It transpires that we also need to undo the SvPVX() sharing when ithreads
cloning a Regexp SV, because mother_re is set to NULL, instead of a
cloned copy of the mother_re. This change might fix bugs with regexps
and threads in certain other situations, but as yet neither tests nor
bug reports have indicated any problems, so it might not actually be an
edge case that it's possible to reach.</p>
</li>
<li>
<p>Several compilation errors and segfaults when perl was built with <code class="inline">-<span class="w">Dmad</span></code>

were fixed.</p>
</li>
<li>
<p>Fixes for lexer API changes in 5.11.2 which broke NYTProf's savesrc option.</p>
</li>
<li>
<p><code class="inline">-t</code>
 should only return TRUE for file handles connected to a TTY</p>
<p>The Microsoft C version of <code class="inline"><span class="i">isatty</span><span class="s">(</span><span class="s">)</span></code>
 returns TRUE for all character mode
devices, including the <i>/dev/null</i>-style "nul" device and printers like
"lpt1".</p>
</li>
<li>
<p>Fixed a regression caused by commit fafafbaf which caused a panic during
parameter passing [perl #70171]</p>
</li>
<li>
<p>On systems which in-place edits without backup files, -i'*' now works as
the documentation says it does [perl #70802]</p>
</li>
<li>
<p>Saving and restoring magic flags no longer loses readonly flag.</p>
</li>
<li>
<p>The malformed syntax <code class="inline"><a class="l_k" href="functions/grep.html">grep</a> <span class="w">EXPR</span> <span class="w">LIST</span></code>
 (note the missing comma) no longer
causes abrupt and total failure.</p>
</li>
<li>
<p>Regular expressions compiled with <code class="inline"><a class="l_k" href="functions/qr.html">qr{}</a></code> literals properly set <code class="inline"><span class="i">$&#39;</span></code>
 when
matching again.</p>
</li>
<li>
<p>Using named subroutines with <code class="inline"><a class="l_k" href="functions/sort.html">sort</a></code> should no longer lead to bus errors
[perl #71076]</p>
</li>
<li>
<p>Numerous bugfixes catch small issues caused by the recently-added Lexer API.</p>
</li>
<li>
<p>Smart match against <code class="inline"><span class="i">@_</span></code>
 sometimes gave false negatives. [perl #71078]</p>
</li>
<li>
<p><code class="inline"><span class="i">$@</span></code>
 may now be assigned a read-only value (without error or busting
the stack).</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/sort.html">sort</a></code> called recursively from within an active comparison subroutine no
longer causes a bus error if run multiple times. [perl #71076]</p>
</li>
<li>
<p>Tie::Hash::NamedCapture::* will not abort if passed bad input (RT #71828)</p>
</li>
<li>
<p>@_ and $_ no longer leak under threads (RT #34342 and #41138, also
#70602, #70974)</p>
</li>
<li>
<p><code class="inline">-<span class="w">I</span></code>
 on shebang line now adds directories in front of @INC
as documented, and as does <code class="inline">-<span class="w">I</span></code>
 when specified on the command-line.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/kill.html">kill</a></code> is now fatal when called on non-numeric process identifiers.
Previously, an <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> process identifier would be interpreted as a
request to kill process 0, which would terminate the current process
group on POSIX systems. Since process identifiers are always integers,
killing a non-numeric process is now fatal.</p>
</li>
<li>
<p>5.10.0 inadvertently disabled an optimisation, which caused a measurable
performance drop in list assignment, such as is often used to assign
function parameters from <code class="inline"><span class="i">@_</span></code>
. The optimisation has been re-instated, and
the performance regression fixed. (This fix is also present in 5.10.1)</p>
</li>
<li>
<p>Fixed memory leak on <code class="inline">while <span class="s">(</span><span class="n">1</span><span class="s">)</span> <span class="s">{</span> <a class="l_k" href="functions/map.html">map</a> <span class="n">1</span><span class="cm">,</span> <span class="n">1</span> <span class="s">}</span></code>
 [RT #53038].</p>
</li>
<li>
<p>Some potential coredumps in PerlIO fixed [RT #57322,54828].</p>
</li>
<li>
<p>The debugger now works with lvalue subroutines.</p>
</li>
<li>
<p>The debugger's <code class="inline"><a class="l_k" href="functions/m.html">m</a></code> command was broken on modules that defined constants
[RT #61222].</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/crypt.html">crypt</a></code> and string complement could return tainted values for untainted
arguments [RT #59998].</p>
</li>
<li>
<p>The <code class="inline">-<span class="w">i</span></code>
<i>.suffix</i> command-line switch now recreates the file using
restricted permissions, before changing its mode to match the original
file. This eliminates a potential race condition [RT #60904].</p>
</li>
<li>
<p>On some Unix systems, the value in <code class="inline"><span class="i">$?</span></code>
 would not have the top bit set
(<code class="inline"><span class="i">$?</span> &amp; <span class="n">128</span></code>
) even if the child core dumped.</p>
</li>
<li>
<p>Under some circumstances, <code class="inline"><span class="i">$^R</span></code>
 could incorrectly become undefined
[RT #57042].</p>
</li>
<li>
<p>In the XS API, various hash functions, when passed a pre-computed hash where
the key is UTF-8, might result in an incorrect lookup.</p>
</li>
<li>
<p>XS code including <i>XSUB.h</i> before <i>perl.h</i> gave a compile-time error
[RT #57176].</p>
</li>
<li>
<p><code class="inline"><span class="i">$object</span><span class="i">-&gt;isa</span><span class="s">(</span><span class="q">&#39;Foo&#39;</span><span class="s">)</span></code>
 would report false if the package <code class="inline"><span class="w">Foo</span></code>

didn't exist, even if the object's <code class="inline"><span class="i">@ISA</span></code>
 contained <code class="inline"><span class="w">Foo</span></code>
.</p>
</li>
<li>
<p>Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
<code class="inline"><span class="i">@ISA</span></code>
, have been found and fixed.</p>
</li>
<li>
<p>Bitwise operations on references could crash the interpreter, e.g.
<code class="inline"><span class="i">$x</span>=\<span class="i">$y</span><span class="sc">;</span> <span class="i">$x</span> |= <span class="q">&quot;foo&quot;</span></code>
 [RT #54956].</p>
</li>
<li>
<p>Patterns including alternation might be sensitive to the internal UTF-8
representation, e.g.</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$byte</span> = <a class="l_k" href="functions/chr.html">chr</a><span class="s">(</span><span class="n">192</span><span class="s">)</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$utf8</span> = <a class="l_k" href="functions/chr.html">chr</a><span class="s">(</span><span class="n">192</span><span class="s">)</span><span class="sc">;</span> <span class="i">utf8::upgrade</span><span class="s">(</span><span class="i">$utf8</span><span class="s">)</span><span class="sc">;</span></li><li>    <span class="i">$utf8</span> =~ <span class="q">/$byte|X}/i</span><span class="sc">;</span>	<span class="c"># failed in 5.10.0</span></li></ol></pre></li>
<li>
<p>Within UTF8-encoded Perl source files (i.e. where <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span></code>
 is in
effect), double-quoted literal strings could be corrupted where a <code class="inline">\<span class="w">xNN</span></code>
,
<code class="inline">\0NNN</code> or <code class="inline">\<span class="w">N</span><span class="s">{</span><span class="s">}</span></code>
 is followed by a literal character with ordinal value
greater than 255 [RT #59908].</p>
</li>
<li>
<p><code class="inline"><span class="w">B::Deparse</span></code>
 failed to correctly deparse various constructs:
<code class="inline"><a class="l_k" href="functions/readpipe.html">readpipe</a> <span class="w">STRING</span></code>
 [RT #62428], <code class="inline"><span class="i">CORE::require</span><span class="s">(</span><span class="w">STRING</span><span class="s">)</span></code>
 [RT #62488],
<code class="inline"><a name="foo"></a>sub <span class="m">foo(_)</span></code>
 [RT #62484].</p>
</li>
<li>
<p>Using <code class="inline"><a class="l_k" href="functions/setpgrp.html">setpgrp</a></code> with no arguments could corrupt the perl stack.</p>
</li>
<li>
<p>The block form of <code class="inline"><a class="l_k" href="functions/eval.html">eval</a></code> is now specifically trappable by <code class="inline"><span class="w">Safe</span></code>
 and
<code class="inline"><span class="w">ops</span></code>
. Previously it was erroneously treated like string <code class="inline"><a class="l_k" href="functions/eval.html">eval</a></code>.</p>
</li>
<li>
<p>In 5.10.0, the two characters <code class="inline">[~</code> were sometimes parsed as the smart
match operator (<code class="inline">~~</code>
) [RT #63854].</p>
</li>
<li>
<p>In 5.10.0, the <code class="inline"><span class="i">*</span></code>
 quantifier in patterns was sometimes treated as
<code class="inline"><span class="s">{</span><span class="n">0</span><span class="cm">,</span><span class="n">32767</span><span class="s">}</span></code>
 [RT #60034, #60464]. For example, this match would fail:</p>
<pre class="verbatim"><ol><li>    <span class="s">(</span><span class="q">&quot;ab&quot;</span> x <span class="n">32768</span><span class="s">)</span> =~ <span class="q">/^(ab)*$/</span></li></ol></pre></li>
<li>
<p><code class="inline"><a class="l_k" href="functions/shmget.html">shmget</a></code> was limited to a 32 bit segment size on a 64 bit OS [RT #63924].</p>
</li>
<li>
<p>Using <code class="inline"><a class="l_k" href="functions/next.html">next</a></code> or <code class="inline"><a class="l_k" href="functions/last.html">last</a></code> to exit a <code class="inline">given</code>
 block no longer produces a
spurious warning like the following:</p>
<pre class="verbatim"><ol><li>    <span class="w">Exiting</span> given <span class="w">via</span> <a class="l_k" href="functions/last.html">last</a> <span class="j">at</span> <span class="w">foo</span>.<span class="w">pl</span> <span class="w">line</span> <span class="n">123</span></li></ol></pre></li>
<li>
<p>Assigning a format to a glob could corrupt the format; e.g.:</p>
<pre class="verbatim"><ol><li>     <span class="i">*bar</span>=<span class="i">*foo</span>{<span class="w">FORMAT</span>}<span class="sc">;</span> <span class="c"># foo format now bad</span></li></ol></pre></li>
<li>
<p>Attempting to coerce a typeglob to a string or number could cause an
assertion failure. The correct error message is now generated,
<code class="inline">Can't coerce GLOB to <i>$type</i></code>.</p>
</li>
<li>
<p>Under <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">filetest</span> <span class="q">&#39;access&#39;</span></code>
, <code class="inline">-x</code>
 was using the wrong access
mode. This has been fixed [RT #49003].</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/length.html">length</a></code> on a tied scalar that returned a Unicode value would not be
correct the first time. This has been fixed.</p>
</li>
<li>
<p>Using an array <code class="inline"><a class="l_k" href="functions/tie.html">tie</a></code> inside in array <code class="inline"><a class="l_k" href="functions/tie.html">tie</a></code> could SEGV. This has been
fixed. [RT #51636]</p>
</li>
<li>
<p>A race condition inside <code class="inline"><span class="i">PerlIOStdio_close</span><span class="s">(</span><span class="s">)</span></code>
 has been identified and
fixed. This used to cause various threading issues, including SEGVs.</p>
</li>
<li>
<p>In <code class="inline"><a class="l_k" href="functions/unpack.html">unpack</a></code>, the use of <code class="inline"><span class="s">(</span><span class="s">)</span></code>
 groups in scalar context was internally
placing a list on the interpreter's stack, which manifested in various
ways, including SEGVs. This is now fixed [RT #50256].</p>
</li>
<li>
<p>Magic was called twice in <code class="inline"><a class="l_k" href="functions/substr.html">substr</a></code>, <code class="inline">\<span class="i">&amp;$x</span></code>
, <code class="inline"><a class="l_k" href="functions/tie.html">tie</a> <span class="i">$x</span><span class="cm">,</span> <span class="i">$m</span></code>
 and <code class="inline"><a class="l_k" href="functions/chop.html">chop</a></code>.
These have all been fixed.</p>
</li>
<li>
<p>A 5.10.0 optimisation to clear the temporary stack within the implicit
loop of <code class="inline"><a class="l_k" href="functions/s.html">s///ge</a></code> has been reverted, as it turned out to be the cause of
obscure bugs in seemingly unrelated parts of the interpreter [commit
ef0d4e17921ee3de].</p>
</li>
<li>
<p>The line numbers for warnings inside <code class="inline">elsif</code>
 are now correct.</p>
</li>
<li>
<p>The <code class="inline">..</code>
 operator now works correctly with ranges whose ends are at or
close to the values of the smallest and largest integers.</p>
</li>
<li>
<p><code class="inline"><a class="l_k" href="functions/binmode.html">binmode</a> <span class="w">STDIN</span><span class="cm">,</span> <span class="q">&#39;:raw&#39;</span></code>
 could lead to segmentation faults on some platforms.
This has been fixed [RT #54828].</p>
</li>
<li>
<p>An off-by-one error meant that <code class="inline"><a class="l_k" href="functions/index.html">index</a> <span class="i">$str</span><span class="cm">,</span> ...</code>
 was effectively being
executed as <code class="inline"><a class="l_k" href="functions/index.html">index</a> <span class="q">&quot;$str\0&quot;</span><span class="cm">,</span> ...</code>
. This has been fixed [RT #53746].</p>
</li>
<li>
<p>Various leaks associated with named captures in regexes have been fixed
[RT #57024].</p>
</li>
<li>
<p>A weak reference to a hash would leak. This was affecting <code class="inline"><span class="w">DBI</span></code>

[RT #56908].</p>
</li>
<li>
<p>Using (?|) in a regex could cause a segfault [RT #59734].</p>
</li>
<li>
<p>Use of a UTF-8 <code class="inline"><a class="l_k" href="functions/tr.html">tr//</a></code> within a closure could cause a segfault [RT #61520].</p>
</li>
<li>
<p>Calling <code class="inline"><span class="i">Perl_sv_chop</span><span class="s">(</span><span class="s">)</span></code>
 or otherwise upgrading an SV could result in an
unaligned 64-bit access on the SPARC architecture [RT #60574].</p>
</li>
<li>
<p>In the 5.10.0 release, <code class="inline"><span class="w">inc_version_list</span></code>
 would incorrectly list
<code class="inline"><span class="n">5.10</span>.<span class="i">*</span></code>
 after <code class="inline"><span class="n">5.8</span>.<span class="i">*</span></code>
; this affected the <code class="inline"><span class="i">@INC</span></code>
 search order
[RT #67628].</p>
</li>
<li>
<p>In 5.10.0, <code class="inline"><a class="l_k" href="functions/pack.html">pack</a> <span class="q">&quot;a*&quot;</span><span class="cm">,</span> <span class="i">$tainted_value</span></code>
 returned a non-tainted value
[RT #52552].</p>
</li>
<li>
<p>In 5.10.0, <code class="inline"><a class="l_k" href="functions/printf.html">printf</a></code> and <code class="inline"><a class="l_k" href="functions/sprintf.html">sprintf</a></code> could produce the fatal error
<code class="inline"><span class="j">panic:</span> <span class="w">utf8_mg_pos_cache_update</span></code>
 when printing UTF-8 strings
[RT #62666].</p>
</li>
<li>
<p>In the 5.10.0 release, a dynamically created <code class="inline">AUTOLOAD</code>
 method might be
missed (method cache issue) [RT #60220,60232].</p>
</li>
<li>
<p>In the 5.10.0 release, a combination of <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">feature</span></code>
 and <code class="inline">//ee</code> could
cause a memory leak [RT #63110].</p>
</li>
<li>
<p><code class="inline">-C</code>
 on the shebang (<code class="inline"><span class="c">#!</span></code>
) line is once more permitted if it is also
specified on the command line. <code class="inline">-C</code>
 on the shebang line used to be a
silent no-op <i>if</i> it was not also on the command line, so perl 5.10.0
disallowed it, which broke some scripts. Now perl checks whether it is
also on the command line and only dies if it is not [RT #67880].</p>
</li>
<li>
<p>In 5.10.0, certain types of re-entrant regular expression could crash,
or cause the following assertion failure [RT #60508]:</p>
<pre class="verbatim"><ol><li>    Assertion rx-&gt;sublen &gt;= (s - rx-&gt;subbeg) + i failed</li></ol></pre></li>
<li>
<p>Perl now includes previously missing files from the Unicode Character
Database.</p>
</li>
<li>
<p>Perl now honors <code class="inline"><span class="w">TMPDIR</span></code>
 when opening an anonymous temporary file.</p>
</li>
</ul>
<a name="Platform-Specific-Changes"></a><h1>Platform Specific Changes</h1>
<p>Perl is incredibly portable. In general, if a platform has a C compiler,
someone has ported Perl to it (or will soon).  We're happy to announce
that Perl 5.12 includes support for several new platforms.  At the same
time, it's time to bid farewell to some (very) old friends.</p>
<a name="New-Platforms"></a><h2>New Platforms</h2>
<ul>
<li><a name="Haiku"></a><b>Haiku</b>
<p>Perl's developers have merged patches from Haiku's maintainers. Perl
should now build on Haiku.</p>
</li>
<li><a name="MirOS-BSD"></a><b>MirOS BSD</b>
<p>Perl should now build on MirOS BSD.</p>
</li>
</ul>
<a name="Discontinued-Platforms"></a><h2>Discontinued Platforms</h2>
<ul>
<li><a name="Domain%2fOS"></a><b>Domain/OS</b>
</li>
<li><a name="MiNT"></a><b>MiNT</b>
</li>
<li><a name="Tenon-MachTen"></a><b>Tenon MachTen</b>
</li>
</ul>
<a name="Updated-Platforms"></a><h2>Updated Platforms</h2>
<ul>
<li><a name="AIX"></a><b>AIX</b>
<ul>
<li>
<p>Removed <i>libbsd</i> for AIX 5L and 6.1. Only <code class="inline"><a class="l_k" href="functions/flock.html">flock()</a></code> was used from
<i>libbsd</i>.</p>
</li>
<li>
<p>Removed <i>libgdbm</i> for AIX 5L and 6.1 if <i>libgdbm</i> &lt; 1.8.3-5 is
installed.  The <i>libgdbm</i> is delivered as an optional package with the
AIX Toolbox.  Unfortunately the versions below 1.8.3-5 are broken.</p>
</li>
<li>
<p>Hints changes mean that AIX 4.2 should work again.</p>
</li>
</ul>
</li>
<li><a name="Cygwin"></a><b>Cygwin</b>
<ul>
<li>
<p>Perl now supports IPv6 on Cygwin 1.7 and newer.</p>
</li>
<li>
<p>On Cygwin we now strip the last number from the DLL. This has been the
behaviour in the cygwin.com build for years. The hints files have been
updated.</p>
</li>
</ul>
</li>
<li><a name="Darwin-(Mac-OS-X)"></a><b>Darwin (Mac OS X)</b>
<ul>
<li>
<p>Skip testing the be_BY.CP1131 locale on Darwin 10 (Mac OS X 10.6),
as it's still buggy.</p>
</li>
<li>
<p>Correct infelicities in the regexp used to identify buggy locales
on Darwin 8 and 9 (Mac OS X 10.4 and 10.5, respectively).</p>
</li>
</ul>
</li>
<li><a name="DragonFly-BSD"></a><b>DragonFly BSD</b>
<ul>
<li>
<p>Fix thread library selection [perl #69686]</p>
</li>
</ul>
</li>
<li><a name="FreeBSD"></a><b>FreeBSD</b>
<ul>
<li>
<p>The hints files now identify the correct threading libraries on FreeBSD 7
and later.</p>
</li>
</ul>
</li>
<li><a name="Irix"></a><b>Irix</b>
<ul>
<li>
<p>We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
<code class="inline"><span class="w">cc</span> -<span class="w">E</span> -</code>
 unfortunately goes into K&amp;R mode, but <code class="inline"><span class="w">cc</span> -<span class="w">E</span> <span class="w">file</span>.<span class="w">c</span></code>
 doesn't.</p>
</li>
</ul>
</li>
<li><a name="NetBSD"></a><b>NetBSD</b>
<ul>
<li>
<p>Hints now supports versions 5.*.</p>
</li>
</ul>
</li>
<li><a name="OpenVMS"></a><b>OpenVMS</b>
<ul>
<li>
<p><code class="inline">-<span class="w">UDEBUGGING</span></code>
 is now the default on VMS.</p>
<p>Like it has been everywhere else for ages and ages. Also make command-line
selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
the only way to turn it off was by saying no in answer to the interactive
question.</p>
</li>
<li>
<p>The default pipe buffer size on VMS has been updated to 8192 on 64-bit
systems.</p>
</li>
<li>
<p>Reads from the in-memory temporary files of <code class="inline"><span class="w">PerlIO::scalar</span></code>
 used to fail
if <code class="inline"><span class="i">$/</span></code>
 was set to a numeric reference (to indicate record-style reads).
This is now fixed.</p>
</li>
<li>
<p>VMS now supports <code class="inline"><a class="l_k" href="functions/getgrgid.html">getgrgid</a></code>.</p>
</li>
<li>
<p>Many improvements and cleanups have been made to the VMS file name handling
and conversion code.</p>
</li>
<li>
<p>Enabling the <code class="inline"><span class="w">PERL_VMS_POSIX_EXIT</span></code>
 logical name now encodes a POSIX exit
status in a VMS condition value for better interaction with GNV's bash
shell and other utilities that depend on POSIX exit values. See
<a href="perlvms.html#%24%3f">$? in perlvms</a> for details.</p>
</li>
<li>
<p><code class="inline"><span class="w">File::Copy</span></code>
 now detects Unix compatibility mode on VMS.</p>
</li>
</ul>
</li>
<li><a name="Stratus-VOS"></a><b>Stratus VOS</b>
<ul>
<li>
<p>Various changes from Stratus have been merged in.</p>
</li>
</ul>
</li>
<li><a name="Symbian"></a><b>Symbian</b>
<ul>
<li>
<p>There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.</p>
</li>
</ul>
</li>
<li><a name="Windows"></a><b>Windows</b>
<ul>
<li>
<p>Perl 5.12 supports Windows 2000 and later. The supporting code for
legacy versions of Windows is still included, but will be removed
during the next development cycle.</p>
</li>
<li>
<p>Initial support for building Perl with MinGW-w64 is now available.</p>
</li>
<li>
<p><i>perl.exe</i> now includes a manifest resource to specify the <code class="inline"><span class="w">trustInfo</span></code>

settings for Windows Vista and later. Without this setting Windows
would treat <i>perl.exe</i> as a legacy application and apply various
heuristics like redirecting access to protected file system areas
(like the "Program Files" folder) to the users "VirtualStore"
instead of generating a proper "permission denied" error.</p>
<p>The manifest resource also requests the Microsoft Common-Controls
version 6.0 (themed controls introduced in Windows XP).  Check out the
Win32::VisualStyles module on CPAN to switch back to old style
unthemed controls for legacy applications.</p>
</li>
<li>
<p>The <code class="inline">-t</code>
 filetest operator now only returns true if the filehandle
is connected to a console window.  In previous versions of Perl it
would return true for all character mode devices, including <i>NUL</i>
and <i>LPT1</i>.</p>
</li>
<li>
<p>The <code class="inline">-p</code>
 filetest operator now works correctly, and the
Fcntl::S_IFIFO constant is defined when Perl is compiled with
Microsoft Visual C.  In previous Perl versions <code class="inline">-p</code>
 always
returned a false value, and the Fcntl::S_IFIFO constant
was not defined.</p>
<p>This bug is specific to Microsoft Visual C and never affected
Perl binaries built with MinGW.</p>
</li>
<li>
<p>The socket error codes are now more widely supported:  The POSIX
module will define the symbolic names, like POSIX::EWOULDBLOCK,
and stringification of socket error codes in $! works as well
now;</p>
<pre class="verbatim"><ol><li>  C:\&gt;perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"</li><li>  A non-blocking socket operation could not be completed immediately.</li></ol></pre></li>
<li>
<p>flock() will now set sensible error codes in $!.  Previous Perl versions
copied the value of $^E into $!, which caused much confusion.</p>
</li>
<li>
<p>select() now supports all empty <code class="inline"><span class="w">fd_set</span></code>
s more correctly.</p>
</li>
<li>
<p><code class="inline"><span class="q">&#39;.\foo&#39;</span></code>
 and <code class="inline"><span class="q">&#39;..\foo&#39;</span></code>
  were treated differently than
<code class="inline"><span class="q">&#39;./foo&#39;</span></code>
 and <code class="inline"><span class="q">&#39;../foo&#39;</span></code>
 by <code class="inline"><a class="l_k" href="functions/do.html">do</a></code> and <code class="inline"><a class="l_k" href="functions/require.html">require</a></code> [RT #63492].</p>
</li>
<li>
<p>Improved message window handling means that <code class="inline"><a class="l_k" href="functions/alarm.html">alarm</a></code> and <code class="inline"><a class="l_k" href="functions/kill.html">kill</a></code> messages
will no longer be dropped under race conditions.</p>
</li>
<li>
<p>Various bits of Perl's build infrastructure are no longer converted to
win32 line endings at release time. If this hurts you, please report the
problem with the <a href="perlbug.html">perlbug</a> program included with perl.</p>
</li>
</ul>
</li>
</ul>
<a name="Known-Problems"></a><h1>Known Problems</h1>
<p>This is a list of some significant unfixed bugs, which are regressions
from either 5.10.x or 5.8.x.</p>
<ul>
<li>
<p>Some CPANPLUS tests may fail if there is a functioning file
<i>../../cpanp-run-perl</i> outside your build directory. The failure
shouldn't imply there's a problem with the actual functional
software. The bug is already fixed in [RT #74188] and is scheduled for
inclusion in perl-v5.12.1.</p>
</li>
<li>
<p><code class="inline"><span class="w">List::Util::first</span></code>
 misbehaves in the presence of a lexical <code class="inline"><span class="i">$_</span></code>

(typically introduced by <code class="inline"><a class="l_k" href="functions/my.html">my</a> <span class="i">$_</span></code>
 or implicitly by <code class="inline">given</code>
). The variable
which gets set for each iteration is the package variable <code class="inline"><span class="i">$_</span></code>
, not the
lexical <code class="inline"><span class="i">$_</span></code>
 [RT #67694].</p>
<p>A similar issue may occur in other modules that provide functions which
take a block as their first argument, like</p>
<pre class="verbatim"><ol><li>    <span class="i">foo</span> <span class="s">{</span> ... <span class="i">$_</span> ...<span class="s">}</span> <span class="w">list</span></li></ol></pre></li>
<li>
<p>Some regexes may run much more slowly when run in a child thread compared
with the thread the pattern was compiled into [RT #55600].</p>
</li>
<li>
<p>Things like <code class="inline"><span class="q">&quot;\N{LATIN SMALL LIGATURE FF}&quot;</span> =~ <span class="q">/\N{LATIN SMALL LETTER F}+/</span></code>

will appear to hang as they get into a very long running loop [RT #72998].</p>
</li>
<li>
<p>Several porters have reported mysterious crashes when Perl's entire
test suite is run after a build on certain Windows 2000 systems. When
run by hand, the individual tests reportedly work fine.</p>
</li>
</ul>
<a name="Errata"></a><h1>Errata</h1>
<ul>
<li>
<p>This one is actually a change introduced in 5.10.0, but it was missed
from that release's perldelta, so it is mentioned here instead.</p>
<p>A bugfix related to the handling of the <code class="inline">/m</code> modifier and <code class="inline"><a class="l_k" href="functions/qr.html">qr</a></code> resulted
in a change of behaviour between 5.8.x and 5.10.0:</p>
<pre class="verbatim"><ol><li>    <span class="c"># matches in 5.8.x, doesn&#39;t match in 5.10.0</span></li><li>    <span class="i">$re</span> = <span class="q">qr/^bar/</span><span class="sc">;</span> <span class="q">&quot;foo\nbar&quot;</span> =~ <span class="q">/$re/m</span><span class="sc">;</span></li></ol></pre></li>
</ul>
<a name="Acknowledgements"></a><h1>Acknowledgements</h1>
<p>Perl 5.12.0 represents approximately two years of development since
Perl 5.10.0 and contains over 750,000 lines of changes across over
3,000 files from over 200 authors and committers.</p>
<p>Perl continues to flourish into its third decade thanks to a vibrant
community of users and developers.  The following people are known to
have contributed the improvements that became Perl 5.12.0:</p>
<p>Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
Adriano Ferreira, &#xc6;var Arnfj&#xf6;r&#xf0; Bjarmason, Alan Grover, Alexandr
Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
John Peacock, John Peacock via RT, John P. Linderman, John Wright,
Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
Lubomir Rintel, Luke Ross, Marcel Gr&#xfc;nauer, Marcus Holland-Moritz, Mark
Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
Rajesh Mandalemula, Reini Urban, Ren&#xe9;e B&#xe4;cker, Ricardo Signes,
Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, S&#xe9;bastien
Aperghis-Tramoni, S&#xe9;rgio Durigan J&#xfa;nior, Shlomi Fish, Simon 'corecode'
Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen M&#xfc;ller, Steffen
Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus</p>
<p>This is woefully incomplete as it's automatically generated from version
control history.  In particular, it doesn't include the names of the
(very much appreciated) contributors who reported issues in previous
versions of Perl that helped make Perl 5.12.0 better. For a more complete
list of all of Perl's historical contributors, please see the <code class="inline"><span class="w">AUTHORS</span></code>

file in the Perl 5.12.0 distribution.</p>
<p>Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
deserve special thanks for their brilliant and substantive ongoing
contributions. Nicholas personally authored over 30% of the patches
since 5.10.0. Rafael comes in second in patch authorship with 11%,
but is first by a long shot in committing patches authored by others,
pushing 44% of the commits since 5.10.0 in this category, often after
providing considerable coaching to the patch authors. These statistics
in no way comprise all of their contributions, but express in shorthand
that we couldn't have done it without them.</p>
<p>Many of the changes included in this version originated in the CPAN
modules included in Perl's core. We're grateful to the entire CPAN
community for helping Perl to flourish.</p>
<a name="Reporting-Bugs"></a><h1>Reporting Bugs</h1>
<p>If you find what you think is a bug, you might check the articles
recently posted to the comp.lang.perl.misc newsgroup and the perl
bug database at <a href="http://rt.perl.org/perlbug/">http://rt.perl.org/perlbug/</a>. There may also be
information at <a href="http://www.perl.org/">http://www.perl.org/</a>, the Perl Home Page.</p>
<p>If you believe you have an unreported bug, please run the <b>perlbug</b>
program included with your release. Be sure to trim your bug down
to a tiny but sufficient test case. Your bug report, along with the
output of <code class="inline"><span class="w">perl</span> -<span class="w">V</span></code>
, will be sent off to perlbug@perl.org to be
analyzed by the Perl porting team.</p>
<p>If the bug you are reporting has security implications, which make it
inappropriate to send to a publicly archived mailing list, then please send
it to perl5-security-report@perl.org. This points to a closed subscription
unarchived mailing list, which includes
all the core committers, who will be able
to help assess the impact of issues, figure out a resolution, and help
co-ordinate the release of patches to mitigate or fix the problem across all
platforms on which Perl is supported. Please only use this address for
security issues in the Perl core, not for modules independently
distributed on CPAN.</p>
<a name="SEE-ALSO"></a><h1>SEE ALSO</h1>
<p>The <i>Changes</i> file for an explanation of how to view exhaustive details
on what changed.</p>
<p>The <i>INSTALL</i> file for how to build Perl.</p>
<p>The <i>README</i> file for general stuff.</p>
<p>The <i>Artistic</i> and <i>Copying</i> files for copyright information.</p>
<p><a href="http://dev.perl.org/perl5/errata.html">http://dev.perl.org/perl5/errata.html</a> for a list of issues
found after this release, as well as a list of CPAN modules known
to be incompatible with this release.</p>




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