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<title>Backward incompatible changes</title>
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</div><hr /><div id="migration71.incompatible" class="sect1">
<h2 class="title">Backward incompatible changes</h2>
<div class="sect2" id="migration71.incompatible.too-few-arguments-exception">
<h3 class="title">Throw on passing too few function arguments</h3>
<p class="para">
Previously, a warning would be emitted for invoking user-defined functions
with too few arguments. Now, this warning has been promoted to an Error
exception. This change only applies to user-defined functions, not internal
functions. For example:
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">$param</span><span style="color: #007700">){}<br /></span><span style="color: #0000BB">test</span><span style="color: #007700">();</span>
</span>
</code></div>
</div>
<p class="para">The above example will output
something similar to:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
Fatal error: Uncaught ArgumentCountError: Too few arguments to function test(), 0 passed in %s on line %d and exactly 1 expected in %s:%d
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.incompatible.forbid-dynamic-calls-to-scope-introspection-functions">
<h3 class="title">Forbid dynamic calls to scope introspection functions</h3>
<p class="para">
Dynamic calls for certain functions have been forbidden (in the form of
<em>$func()</em> or <em>array_map('extract', ...)</em>,
etc). These functions either inspect or modify another scope, and present
with them ambiguous and unreliable behavior. The functions are as follows:
</p>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.assert.html" class="function">assert()</a></span> - with a string as the first argument
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.compact.html" class="function">compact()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.extract.html" class="function">extract()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.func-get-args.html" class="function">func_get_args()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.func-get-arg.html" class="function">func_get_arg()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.func-num-args.html" class="function">func_num_args()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.get-defined-vars.html" class="function">get_defined_vars()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.mb-parse-str.html" class="function">mb_parse_str()</a></span> - with one arg
</span>
</li>
<li class="listitem">
<span class="simpara">
<span class="function"><a href="function.parse-str.html" class="function">parse_str()</a></span> - with one arg
</span>
</li>
</ul>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">(function () {<br /> </span><span style="color: #0000BB">$func </span><span style="color: #007700">= </span><span style="color: #DD0000">'func_num_args'</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$func</span><span style="color: #007700">();<br />})();</span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
Warning: Cannot call func_num_args() dynamically in %s on line %d
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.incompatible.invalid-class-names">
<h3 class="title">Invalid class, interface, and trait names</h3>
<p class="para">
The following names cannot be used to name classes, interfaces, or traits:
</p>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara"><span class="type"><span class="type void">void</span></span></span>
</li>
<li class="listitem">
<span class="simpara"><span class="type"><span class="type iterable">iterable</span></span></span>
</li>
</ul>
</div>
<div class="sect2" id="migration71.incompatible.numerical-strings-scientific-notation">
<h3 class="title">Numerical string conversions now respect scientific notation</h3>
<p class="para">
Integer operations and conversions on numerical strings now respect
scientific notation. This also includes the <em>(int)</em> cast
operation, and the following functions: <span class="function"><a href="function.intval.html" class="function">intval()</a></span> (where
the base is 10), <span class="function"><a href="function.settype.html" class="function">settype()</a></span>, <span class="function"><a href="function.decbin.html" class="function">decbin()</a></span>,
<span class="function"><a href="function.decoct.html" class="function">decoct()</a></span>, and <span class="function"><a href="function.dechex.html" class="function">dechex()</a></span>.
</p>
</div>
<div class="sect2" id="migration71.incompatible.fixes-to-mt_rand-algorithm">
<h3 class="title">Fixes to <span class="function"><a href="function.mt-rand.html" class="function">mt_rand()</a></span> algorithm</h3>
<p class="para">
<span class="function"><a href="function.mt-rand.html" class="function">mt_rand()</a></span> will now default to using the fixed version of
the Mersenne Twister algorithm. If deterministic output from
<span class="function"><a href="function.mt-srand.html" class="function">mt_srand()</a></span> was relied upon, then the
<strong><code>MT_RAND_PHP</code></strong> with the ability to preserve the old
(incorrect) implementation via an additional optional second parameter to
<span class="function"><a href="function.mt-srand.html" class="function">mt_srand()</a></span>.
</p>
</div>
<div class="sect2" id="migration71.incompatible.rand-srand-aliases">
<h3 class="title">
<span class="function"><a href="function.rand.html" class="function">rand()</a></span> aliased to <span class="function"><a href="function.mt-rand.html" class="function">mt_rand()</a></span> and
<span class="function"><a href="function.srand.html" class="function">srand()</a></span> aliased to <span class="function"><a href="function.mt-srand.html" class="function">mt_srand()</a></span>
</h3>
<p class="para">
<span class="function"><a href="function.rand.html" class="function">rand()</a></span> and <span class="function"><a href="function.srand.html" class="function">srand()</a></span> have now been made
aliases to <span class="function"><a href="function.mt-rand.html" class="function">mt_rand()</a></span> and <span class="function"><a href="function.mt-srand.html" class="function">mt_srand()</a></span>,
respectively. This means that the output for the following functions have
changes: <span class="function"><a href="function.rand.html" class="function">rand()</a></span>, <span class="function"><a href="function.shuffle.html" class="function">shuffle()</a></span>,
<span class="function"><a href="function.str-shuffle.html" class="function">str_shuffle()</a></span>, and <span class="function"><a href="function.array-rand.html" class="function">array_rand()</a></span>.
</p>
</div>
<div class="sect2" id="migration71.incompatible.delete-control-character-in-identifiers">
<h3 class="title">Disallow the ASCII delete control character in identifiers</h3>
<p class="para">
The ASCII delete control character (<em>0x7F</em>) can no longer
be used in identifiers that are not quoted.
</p>
</div>
<div class="sect2" id="migration71.incompatible.error_log-syslog">
<h3 class="title">
<code class="parameter">error_log</code> changes with <em>syslog</em>
value
</h3>
<p class="para">
If the <code class="parameter">error_log</code> ini setting is set to
<em>syslog</em>, the PHP error levels are mapped to the syslog
error levels. This brings finer differentiation in the error logs in
contrary to the previous approach where all the errors are logged with the
notice level only.
</p>
</div>
<div class="sect2" id="migration71.incompatible.dont-call-destructors">
<h3 class="title">Do not call destructors on incomplete objects</h3>
<p class="para">
Destructors are now never called for objects that throw an exception during
the execution of their constructor. In previous versions this behavior
depended on whether the object was referenced outside the constructor (e.g.
by an exception backtrace).
</p>
</div>
<div class="sect2" id="migration71.incompatible.call_user_func-with-ref-args">
<h3 class="title">
<span class="function"><a href="function.call-user-func.html" class="function">call_user_func()</a></span> handling of reference arguments
</h3>
<p class="para">
<span class="function"><a href="function.call-user-func.html" class="function">call_user_func()</a></span> will now always generate a warning
upon calls to functions that expect references as arguments. Previously
this depended on whether the call was fully qualified.
</p>
<p class="para">
Additionally, <span class="function"><a href="function.call-user-func.html" class="function">call_user_func()</a></span> and
<span class="function"><a href="function.call-user-func-array.html" class="function">call_user_func_array()</a></span> will no longer abort the function
call in this case. The "expected reference" warning will be emitted, but the
call will proceed as usual.
</p>
</div>
<div class="sect2" id="migration71.incompatible.empty-string-index-operator">
<h3 class="title">
The empty index operator is not supported for strings anymore
</h3>
<p class="para">
Applying the empty index operator to a string (e.g. <em>$str[] = $x</em>)
throws a fatal error instead of converting silently to array.
</p>
</div>
<div class="sect2" id="migration71.incompatible.removed-ini-directives">
<h3 class="title">Removed ini directives</h3>
<p class="para">
The following ini directives have been removed:
</p>
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
<code class="parameter">session.entropy_file</code>
</span>
</li>
<li class="listitem">
<span class="simpara">
<code class="parameter">session.entropy_length</code>
</span>
</li>
<li class="listitem">
<span class="simpara">
<code class="parameter">session.hash_function</code>
</span>
</li>
<li class="listitem">
<span class="simpara">
<code class="parameter">session.hash_bits_per_character</code>
</span>
</li>
</ul>
</div>
<div class="sect2" id="migration71.incompatible.array-order">
<h3 class="title">
Array ordering when elements are automatically created during by reference
assignments has changed
</h3>
<p class="para">
The order of the elements in an array has changed when those elements have
been automatically created by referencing them in a by reference
assignment. For example:
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= [];<br /></span><span style="color: #0000BB">$array</span><span style="color: #007700">[</span><span style="color: #DD0000">"a"</span><span style="color: #007700">] =& </span><span style="color: #0000BB">$array</span><span style="color: #007700">[</span><span style="color: #DD0000">"b"</span><span style="color: #007700">];<br /></span><span style="color: #0000BB">$array</span><span style="color: #007700">[</span><span style="color: #DD0000">"b"</span><span style="color: #007700">] = </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<p class="para">Output of the above example in PHP 7.0:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
array(2) {
["a"]=>
&int(1)
["b"]=>
&int(1)
}
</pre></div>
</div>
<p class="para">Output of the above example in PHP 7.1:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
array(2) {
["b"]=>
&int(1)
["a"]=>
&int(1)
}
</pre></div>
</div>
</div>
</div>
<div class="sect2" id="migration71.incompatible.sort-order">
<h3 class="title">Sort order of equal elements</h3>
<p class="para">
The internal sorting algorithm has been improved, what may result in
different sort order of elements, which compare as equal, than before.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Don't rely on the order of elements which compare as equal; it might change
anytime.
</p>
</p></blockquote>
</div>
<div class="sect2" id="migration71.incompatible.e-recoverable">
<h3 class="title">Error message for E_RECOVERABLE errors</h3>
<p class="para">
The error message for E_RECOVERABLE errors has been changed from "Catchable
fatal error" to "Recoverable fatal error".
</p>
</div>
<div class="sect2" id="migration71.incompatible.unserialize">
<h3 class="title">$options parameter of unserialize()</h3>
<p class="para">
The <em>allowed_classes</em> element of the $options parameter of
<span class="function"><a href="function.unserialize.html" class="function">unserialize()</a></span> is now strictly typed, i.e. if anything
other than an <span class="type"><a href="language.types.array.html" class="type array">array</a></span> or a <span class="type"><a href="language.types.boolean.html" class="type boolean">boolean</a></span> is given,
unserialize() returns <strong><code>FALSE</code></strong> and issues an <strong><code>E_WARNING</code></strong>.
</p>
</div>
<div class="sect2" id="migration71.incompatible.datetime-microseconds">
<h3 class="title">DateTime constructor incorporates microseconds</h3>
<p class="para">
<a href="class.datetime.html" class="classname">DateTime</a> and <a href="class.datetimeimmutable.html" class="classname">DateTimeImmutable</a>
now properly incorporate microseconds when constructed from the current time,
either explicitly or with a relative string (e.g. <em>"first day of next
month"</em>). This means that naive comparisons of two newly created
instances will now more likely return <strong><code>FALSE</code></strong> instead of <strong><code>TRUE</code></strong>:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">new </span><span style="color: #0000BB">DateTime</span><span style="color: #007700">() == new </span><span style="color: #0000BB">DateTime</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="sect2" id="migration71.incompatible.fatal-errors-to-error-exceptions">
<h3 class="title">Fatal errors to <a href="class.error.html" class="classname">Error</a> exceptions conversions</h3>
<p class="para">
In the Date extension, invalid serialization data for
<a href="class.datetime.html" class="classname">DateTime</a> or <a href="class.dateperiod.html" class="classname">DatePeriod</a> classes,
or timezone initialization failure from serialized data, will now throw an
<a href="class.error.html" class="classname">Error</a> exception from the
<span class="methodname"><strong>__wakeup()</strong></span> or <span class="methodname"><strong>__set_state()</strong></span>
methods, instead of resulting in a fatal error.
</p>
<p class="para">
In the DBA extension, data modification functions (such as
<span class="function"><a href="function.dba-insert.html" class="function">dba_insert()</a></span>) will now throw an
<a href="class.error.html" class="classname">Error</a> exception instead of triggering a catchable
fatal error if the key does not contain exactly two elements.
</p>
<p class="para">
In the DOM extension, invalid schema or RelaxNG validation contexts will now
throw an <a href="class.error.html" class="classname">Error</a> exception instead of resulting in a
fatal error. Similarly, attempting to register a node class that does not
extend the appropriate base class, or attempting to read an invalid property
or write to a readonly property, will also now throw an
<a href="class.error.html" class="classname">Error</a> exception.
</p>
<p class="para">
In the IMAP extension, email addresses longer than 16385 bytes will throw an
<a href="class.error.html" class="classname">Error</a> exception instead of resulting in a fatal error.
</p>
<p class="para">
In the Intl extension, failing to call the parent constructor in a class
extending <a href="class.collator.html" class="classname">Collator</a> before invoking the parent methods
will now throw an <a href="class.error.html" class="classname">Error</a> instead of resulting in a
recoverable fatal error. Also, cloning a
<a href="class.transliterator.html" class="classname">Transliterator</a> object will now throw an
<a href="class.error.html" class="classname">Error</a> exception on failure to clone the internal
transliterator instead of resulting in a fatal error.
</p>
<p class="para">
In the LDAP extension, providing an unknown modification type to
<span class="function"><strong>ldap_batch_modify()</strong></span> will now throw an
<a href="class.error.html" class="classname">Error</a> exception instead of resulting in a fatal error.
</p>
<p class="para">
In the mbstring extension, the <span class="function"><a href="function.mb-ereg.html" class="function">mb_ereg()</a></span> and
<span class="function"><a href="function.mb-eregi.html" class="function">mb_eregi()</a></span> functions will now throw a
<a href="class.parseerror.html" class="classname">ParseError</a> exception if an invalid PHP expression is
provided and the 'e' option is used.
</p>
<p class="para">
In the Mcrypt extension, the <span class="function"><a href="function.mcrypt-encrypt.html" class="function">mcrypt_encrypt()</a></span> and
<span class="function"><a href="function.mcrypt-decrypt.html" class="function">mcrypt_decrypt()</a></span> will now throw an
<a href="class.error.html" class="classname">Error</a> exception instead of resulting in a fatal error
if mcrypt cannot be initialized.
</p>
<p class="para">
In the mysqli extension, attempting to read an invalid property or write to
a readonly property will now throw an <a href="class.error.html" class="classname">Error</a> exception
instead of resulting in a fatal error.
</p>
<p class="para">
In the Reflection extension, failing to retrieve a reflection object or
retrieve an object property will now throw an <a href="class.error.html" class="classname">Error</a>
exception instead of resulting in a fatal error.
</p>
<p class="para">
In the Session extension, custom session handlers that do not return strings
for session IDs will now throw an <a href="class.error.html" class="classname">Error</a> exception
instead of resulting in a fatal error when a function is called that must
generate a session ID.
</p>
<p class="para">
In the SimpleXML extension, creating an unnamed or duplicate attribute will
now throw an <a href="class.error.html" class="classname">Error</a> exception instead of resulting in
a fatal error.
</p>
<p class="para">
In the SPL extension, attempting to clone an
<strong class="classname">SplDirectory</strong> object will now throw an
<a href="class.error.html" class="classname">Error</a> exception instead of resulting in a fatal
error. Similarly, calling <span class="methodname"><a href="arrayiterator.append.html" class="methodname">ArrayIterator::append()</a></span> when
iterating over an object will also now throw an <a href="class.error.html" class="classname">Error</a>
exception.
</p>
<p class="para">
In the standard extension, the <span class="function"><a href="function.assert.html" class="function">assert()</a></span> function, when
provided with a string argument as its first parameter, will now throw a
<a href="class.parseerror.html" class="classname">ParseError</a> exception instead of resulting in a
catchable fatal error if the PHP code is invalid. Similarly, calling
<span class="function"><a href="function.forward-static-call.html" class="function">forward_static_call()</a></span> outside of a class scope will now
throw an <a href="class.error.html" class="classname">Error</a> exception.
</p>
<p class="para">
In the Tidy extension, creating a <a href="class.tidynode.html" class="classname">tidyNode</a> manually
will now throw an <a href="class.error.html" class="classname">Error</a> exception instead of
resulting in a fatal error.
</p>
<p class="para">
In the WDDX extension, a circular reference when serializing will now throw
an <a href="class.error.html" class="classname">Error</a> exception instead of resulting in a fatal
error.
</p>
<p class="para">
In the XML-RPC extension, a circular reference when serializing will now
throw an instance of <a href="class.error.html" class="classname">Error</a> exception instead of
resulting in a fatal error.
</p>
<p class="para">
In the Zip extension, the <span class="methodname"><a href="ziparchive.addglob.html" class="methodname">ZipArchive::addGlob()</a></span>
method will now throw an <a href="class.error.html" class="classname">Error</a> exception instead of
resulting in a fatal error if glob support is not available.
</p>
</div>
<div class="sect2" id="migration71.incompatible.lexical-names">
<h3 class="title">Lexically bound variables cannot reuse names</h3>
<p class="para">
Variables bound to a <a href="functions.anonymous.html" class="link">closure</a> via
the <em>use</em> construct cannot use the same name as any
<a href="language.variables.predefined.html" class="link">superglobals</a>, <var class="varname"><var class="varname">$this</var></var>, or any parameter. For
example, all of these function definition will result in a fatal error:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$f </span><span style="color: #007700">= function () use (</span><span style="color: #0000BB">$_SERVER</span><span style="color: #007700">) {};<br /></span><span style="color: #0000BB">$f </span><span style="color: #007700">= function () use (</span><span style="color: #0000BB">$this</span><span style="color: #007700">) {};<br /></span><span style="color: #0000BB">$f </span><span style="color: #007700">= function (</span><span style="color: #0000BB">$param</span><span style="color: #007700">) use (</span><span style="color: #0000BB">$param</span><span style="color: #007700">) {};</span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="sect2" id="migration71.incompatible.long2ip">
<h3 class="title">long2ip() parameter type change</h3>
<p class="para">
<span class="function"><a href="function.long2ip.html" class="function">long2ip()</a></span> now expects an <span class="type"><a href="language.types.integer.html" class="type int">int</a></span> instead of a
<span class="type"><a href="language.types.string.html" class="type string">string</a></span>.
</p>
</div>
<div class="sect2" id="migration71.incompatible.json">
<h3 class="title">JSON encoding and decoding</h3>
<p class="para">
The <code class="parameter">serialize_precision</code> ini setting now controls the
serialization precision when encoding doubles.
</p>
<p class="para">
Decoding an empty key now results in an empty property name, rather than
<em>_empty_</em> as a property name.
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">json_encode</span><span style="color: #007700">([</span><span style="color: #DD0000">'' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">])));</span>
</span>
</code></div>
</div>
<p class="para">The above example will output
something similar to:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
object(stdClass)#1 (1) {
[""]=>
int(1)
}
</pre></div>
</div>
</div>
</p>
<p class="para">
When supplying the <strong><code>JSON_UNESCAPED_UNICODE</code></strong> flag to
<span class="function"><a href="function.json-encode.html" class="function">json_encode()</a></span>, the sequences U+2028 and U+2029 are now
escaped.
</p>
</div>
<div class="sect2" id="migration71.incompatible.mbstring">
<h3 class="title">
Changes to <span class="function"><a href="function.mb-ereg.html" class="function">mb_ereg()</a></span> and <span class="function"><a href="function.mb-eregi.html" class="function">mb_eregi()</a></span>
parameter semantics
</h3>
<p class="para">
The third parameter to the <span class="function"><a href="function.mb-ereg.html" class="function">mb_ereg()</a></span> and
<span class="function"><a href="function.mb-eregi.html" class="function">mb_eregi()</a></span> functions (<code class="parameter">regs</code>) will now be
set to an empty array if nothing was matched. Formerly, the parameter would
not have been modified.
</p>
</div>
<div class="sect2" id="migration71.incompatible.openssl">
<h3 class="title">Drop support for the sslv2 stream</h3>
<p class="para">
The sslv2 stream has now been dropped in OpenSSL.
</p>
</div>
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