- Core：

  . Added support for typed properties. For example:

        class User {

            public int $id;

            public string $name;

        }

    This will enforce that $user->id can only be assigned integer and

    $user->name can only be assigned strings. For more information see the

    RFC: https://wiki.php.net/rfc/typed_properties_v2

  . Added support for arrow functions with implicit by-value scope binding.

    For example:

        $factor = 10;

        $nums = array_map(fn($num) => $num * $factor, $nums);

    RFC: https://wiki.php.net/rfc/arrow_functions_v2

  . Added support for limited return type covariance and argument type

    contravariance. The following code will now work:

        class A {}

        class B extends A {}

        class Producer {

            public function method(): A {}

        }

        class ChildProducer extends Producer {

            public function method(): B {}

        }

    Full variance support is only available if autoloading is used. Inside a

    single file only non-cyclic type references are possible, because all

    classes need to be available before they are referenced.

    RFC: https://wiki.php.net/rfc/covariant-returns-and-contravariant-parameters

  . Added support for coalesce assign (??=) operator. For example:

        $array['key'] ??= computeDefault();

        // is roughly equivalent to

        if (!isset($array['key'])) {

            $array['key'] = computeDefault();

        }

    RFC: https://wiki.php.net/rfc/null_coalesce_equal_operator

  . Added support for unpacking inside arrays. For example:

        $arr1 = [3, 4];

        $arr2 = [1, 2, ...$arr1, 5];

        // $arr2 == [1, 2, 3, 4, 5]

    RFC: https://wiki.php.net/rfc/spread_operator_for_array

  . Support for WeakReferences has been added.

    RFC: https://wiki.php.net/rfc/weakrefs

  . Throwing exceptions from __toString() is now permitted. Previously this

    resulted in a fatal error. Existing recoverable fatals in string conversions

    have been converted to Error exceptions.

    RFC: https://wiki.php.net/rfc/tostring_exceptions

- CURL:

  . CURLFile now supports stream wrappers in addition to plain file names, if

    the extension has been built against libcurl >= 7.56.0.  The streams may

    need to be seekable.

- Filter:

  . The FILTER_VALIDATE_FLOAT filter now supports the min_range and max_range

    options, with the same semantics as FILTER_VALIDATE_INT.

- FFI:

  . A new extension which provides a simple way to call native functions, access

    native variables and create/access data structures defined in C libraries.

    RFC: https://wiki.php.net/rfc/ffi

- GD:

  . Added the "scatter" image filter (IMG_FILTER_SCATTER) to apply a scatter

    filter to images. This filter has the following prototype:

        imagefilter($im, IMG_FILTER_SCATTER, int $sub, int $plus, array $colors = []);

    The $colors array can be populated with a set of indexed colors where to

    apply the scatter pixel shifting on.

    Note, the result of this filter is always random.

- Hash:

  . Added "crc32c" hash using Castagnoli's polynomial. This crc32 variant is

    used by storage systems, such as iSCSI, SCTP, Btrfs and ext4.

- Mbstring:

  . Added mb_str_split() function, which provide the same functionality as

    str_split(), but operating on code points rather than bytes.

    RFC: https://wiki.php.net/rfc/mb_str_split

- OPcache:

  . Support for preloading code has been added.

    RFC: https://wiki.php.net/rfc/preload

- PCRE:

  . The preg_replace_callback() and preg_replace_callback_array() functions now

    accept an additional $flags argument, with support for the

    PREG_OFFSET_CAPTURE and PREG_UNMATCHED_AS_NULL flags. This influences the

    format of the matches array passed to to the callback function.

- PDO_OCI:

  . PDOStatement::getColumnMeta() is now available

- PDO_SQLite:

  . PDOStatement::getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT) allows to

    check whether this statement is read-only, i.e. whether it doesn't modify

    the database.

- Standard:

  . strip_tags() now also accepts an array of allowed tags: Instead of

    strip_tags($str, '<a><p>') you can now write strip_tags($str, ['a', 'p']).

  . A new mechanism for custom object serialization has been added, which

    uses two new magic methods:

        // Returns array containing all the necessary state of the object.

        public function __serialize(): array;

        // Restores the object state from the given data array.

        public function __unserialize(array $data): void;

    The new serialization mechanism supersedes the Serializable interface,

    which will be deprecated in the future.

    RFC: https://wiki.php.net/rfc/custom_object_serialization

  . array_merge() and array_merge_recursive() may now be called without any

    arguments, in which case they will return an empty array. This is useful

    in conjunction with the spread operator, e.g. array_merge(...$arrays).