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<sect1 xml:id="migration74.incompatible" xmlns:xlink="http://www.w3.org/1999/xlink">

<title>Backward Incompatible Changes</title>

<sect2 xml:id="migration74.incompatible.core">

<title>PHP Core</title>

<sect3 xml:id="migration74.incompatible.core.non-array-access">

<title>Array-style access of non-arrays</title>

<para>

Trying to use values of type <type>null</type>, <type>bool</type>,

<type>int</type>, <type>float</type> or <type>resource</type> as an

array (such as <literal>$null["key"]</literal>) will now generate a notice.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.get-declared-classes">

<title><function>get_declared_classes</function> function</title>

<para>

The <function>get_declared_classes</function> function no longer

returns anonymous classes that have not been instantiated yet.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.fn">

<title><literal>fn</literal> keyword</title>

<para>

<literal>fn</literal> is now a reserved keyword. In particular,

it can no longer be used as a function or class name.

It can still be used as a method or class constant name.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.php-tag">

<title><literal>&lt;?php</literal> tag at end of file</title>

<para>

<literal>&lt;?php</literal> at the end of the file (without trailing newline)

will now be interpreted as an opening PHP tag. Previously it was interpreted

either as a short opening tag followed by literal <literal>php</literal> and

resulted in a syntax error (with <literal>short_open_tag=1</literal>)

or was interpreted as a literal <literal>&lt;?php</literal> string

(with <literal>short_open_tag=0</literal>).

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.stream-wrappers">

<title>Stream wrappers</title>

<para>

When using include/require on a stream,

<methodname>streamWrapper::stream_set_option</methodname>

will be invoked with the <constant>STREAM_OPTION_READ_BUFFER</constant> option.

Custom stream wrapper implementations may need to implement the

<methodname>streamWrapper::stream_set_option</methodname> method to

avoid a warning (always returning &false; is a sufficient implementation).

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.serialization">

<title>Serialization</title>

<para>

The <literal>o</literal> serialization format has been removed.

As it is never produced by PHP, this may only break unserialization of

manually crafted strings.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.password-algorithm-constants">

<title>Password algorithm constants</title>

<para>

Password hashing algorithm identifiers are now nullable strings rather

than integers.

</para>

<itemizedlist>

<listitem>

<simpara>

<constant>PASSWORD_DEFAULT</constant> was int 1; now is string '2y' (in PHP 7.4.0, 7.4.1, and 7.4.2 it was &null;)

</simpara>

</listitem>

<listitem>

<simpara>

<constant>PASSWORD_BCRYPT</constant> was int 1; now is string '2y'

</simpara>

</listitem>

<listitem>

<simpara>

<constant>PASSWORD_ARGON2I</constant> was int 2; now is string 'argon2i'

</simpara>

</listitem>

<listitem>

<simpara>

<constant>PASSWORD_ARGON2ID</constant> was int 3; now is string 'argon2id'

</simpara>

</listitem>

</itemizedlist>

<para>

Applications correctly using the constants PASSWORD_DEFAULT,

PASSWORD_BCRYPT, PASSWORD_ARGON2I, and PASSWORD_ARGON2ID will continue to

function correctly.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.htmlentities">

<title><function>htmlentities</function> function</title>

<para>

<function>htmlentities</function> will now raise a notice

(instead of a strict standards warning) if it is used with

an encoding for which only basic entity substitution is supported,

in which case it is equivalent to <function>htmlspecialchars</function>.

</para>

</sect3>

<sect3 xml:id="migration74.incompatible.core.fread-fwrite">

<title><function>fread</function> and <function>fwrite</function> function</title>

<para>

<function>fread</function> and <function>fwrite</function> will now

return &false; if the operation failed.

Previously an empty string or 0 was returned.

EAGAIN/EWOULDBLOCK are not considered failures.

</para>

<para>

These functions now also raise a notice on failure,

such as when trying to write to a read-only file resource.

</para>

</sect3>

</sect2>

<sect2 xml:id="migration74.incompatible.bcmath">

<title>BCMath Arbitrary Precision Mathematics</title>

<para>

BCMath functions will now warn if a non well-formed number is passed, such

as <literal>"32foo"</literal>. The argument will be interpreted as zero, as before.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.curl">

<title>CURL</title>

<para>

Attempting to serialize a <classname>CURLFile</classname> class will now

generate an exception. Previously the exception was only thrown on unserialization.

</para>

<para>

Using <constant>CURLPIPE_HTTP1</constant> is deprecated, and is no longer

supported as of cURL 7.62.0.

</para>

<para>

The <literal>$version</literal> parameter of <function>curl_version</function>

is deprecated. If any value not equal to the default <constant>CURLVERSION_NOW</constant>

is passed, a warning is raised and the parameter is ignored.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.datetime">

<title>Date and Time</title>

<para>

Calling <function>var_dump</function> or similar on a

<classname>DateTime</classname> or <classname>DateTimeImmutable</classname>

instance will no longer leave behind accessible properties on the object.

</para>

<para>

Comparison of <classname>DateInterval</classname> objects

(using <literal>==</literal>, <literal>&lt;</literal>, and so on) will now generate

a warning and always return &false;. Previously all <classname>DateInterval</classname>

objects were considered equal, unless they had properties.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.intl">

<title>Intl</title>

<para>

The default parameter value of <function>idn_to_ascii</function> and

<function>idn_to_utf8</function> is now <constant>INTL_IDNA_VARIANT_UTS46</constant>

instead of the deprecated <constant>INTL_IDNA_VARIANT_2003</constant>.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.mysqli">

<title>MySQLi</title>

<para>

The embedded server functionality has been removed. It was broken since

at least PHP 7.0.

</para>

<para>

The undocumented <literal>mysqli::$stat</literal> property has been removed

in favor of <methodname>mysqli::stat</methodname>.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.openssl">

<title>OpenSSL</title>

<para>

The <function>openssl_random_pseudo_bytes</function> function will now

throw an exception in error situations, similar to <function>random_bytes</function>.

In particular, an <classname>Error</classname> is thrown if the number of

requested bytes is less than or equal to zero, and an <classname>Exception</classname>

is thrown if sufficient randomness cannot be gathered.

The <literal>$crypto_strong</literal> output argument is guaranteed to always

be &true; if the function does not throw, so explicitly checking it is not necessary.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.pcre">

<title>Regular Expressions (Perl-Compatible)</title>

<para>

When <constant>PREG_UNMATCHED_AS_NULL</constant> mode is used, trailing

unmatched capturing groups will now also be set to &null; (or

<literal>[null, -1]</literal> if offset capture is enabled).

This means that the size of the <literal>$matches</literal> will always be the same.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.pdo">

<title>PHP Data Objects</title>

<para>

Attempting to serialize a <classname>PDO</classname> or

<classname>PDOStatement</classname> instance will now generate

an <classname>Exception</classname> rather than a <classname>PDOException</classname>,

consistent with other internal classes which do not support serialization.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.reflection">

<title>Reflection</title>

<para>

Reflection objects will now generate an exception if an attempt is made

to serialize them. Serialization for reflection objects was never

supported and resulted in corrupted reflection objects. It has been

explicitly prohibited now.

</para>

<para>

The values of the class constant of <classname>ReflectionClassConstant</classname>,

<classname>ReflectionMethod</classname> and <classname>ReflectionProperty</classname>

have changed.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.spl">

<title>Standard PHP Library (SPL)</title>

<para>

Calling <function>get_object_vars</function> on an <classname>ArrayObject</classname>

instance will now always return the properties of the <classname>ArrayObject</classname>

itself (or a subclass). Previously it returned the values of the wrapped

array/object unless the <constant>ArrayObject::STD_PROP_LIST</constant>

flag was specified.

</para>

<para>

Other affected operations are:

</para>

<itemizedlist>

<listitem>

<simpara>

<methodname>ReflectionObject::getProperties</methodname>

</simpara>

</listitem>

<listitem>

<simpara>

<function>reset</function>, <function>current</function>, etc.

Use <interfacename>Iterator</interfacename> methods instead.

</simpara>

</listitem>

<listitem>

<simpara>

Potentially others working on object properties as a list,

e.g. <function>array_walk</function>.

</simpara>

</listitem>

</itemizedlist>

<para>

<literal>(array)</literal> casts are not affected. They will continue to

return either the wrapped array, or the <classname>ArrayObject</classname>

properties, depending on whether the <constant>ArrayObject::STD_PROP_LIST</constant>

flag is used.

</para>

<para>

<methodname>SplPriorityQueue::setExtractFlags</methodname> will throw

an exception if zero is passed. Previously this would generate a recoverable

fatal error on the next extraction operation.

</para>

<para>

<classname>ArrayObject</classname>, <classname>ArrayIterator</classname>,

<classname>SplDoublyLinkedList</classname> and <classname>SplObjectStorage</classname>

now support the <literal>__serialize()</literal> and <literal>__unserialize()</literal>

mechanism in addition to the <interfacename>Serializable</interfacename> interface.

This means that serialization payloads created on older PHP versions can still be

unserialized, but new payloads created by PHP 7.4 will not be understood by older versions.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.tokenizer">

<title>Tokenizer</title>

<para>

<function>token_get_all</function> will now emit a

<constant>T_BAD_CHARACTER</constant> token for unexpected

characters instead of leaving behind holes in the token stream.

</para>

</sect2>

<sect2 xml:id="migration74.incompatible.cookie-decode">

<title>Incoming Cookies</title>

<para>

As of PHP 7.4.11, the <emphasis>names</emphasis> of incoming cookies are no

longer url-decoded for security reasons.

</para>

</sect2>

</sect1>

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