Code Modernization: Silence the deprecation warnings for missing return type in WP_Hook.

This fixes the "Deprecated: Return type of `WP_Hook::[METHODNAME]()` should be compatible with `ArrayAccess::[METHODNAME](): type`" warnings on PHP 8.1.

PHP native interfaces now have declared return types and methods in classes implementing these interfaces need to either have the return type declared (in a covariant compatible manner with the PHP native interface method declaration), or need to silence the deprecation warning using the `#[ReturnTypeWillChange]` attribute.

Follow-up to [51517], [51529].

Props jrf.
See #53635.

git-svn-id: https://develop.svn.wordpress.org/trunk@51530 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/class-wp-hook.php

@@ -437,6 +437,7 @@ public static function build_preinitialized_hooks( $filters ) {
 	 * @param mixed $offset An offset to check for.
 	 * @return bool True if the offset exists, false otherwise.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetExists( $offset ) {
 		return isset( $this->callbacks[ $offset ] );
 	}
@@ -451,6 +452,7 @@ public function offsetExists( $offset ) {
 	 * @param mixed $offset The offset to retrieve.
 	 * @return mixed If set, the value at the specified offset, null otherwise.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetGet( $offset ) {
 		return isset( $this->callbacks[ $offset ] ) ? $this->callbacks[ $offset ] : null;
 	}
@@ -465,6 +467,7 @@ public function offsetGet( $offset ) {
 	 * @param mixed $offset The offset to assign the value to.
 	 * @param mixed $value The value to set.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetSet( $offset, $value ) {
 		if ( is_null( $offset ) ) {
 			$this->callbacks[] = $value;
@@ -482,6 +485,7 @@ public function offsetSet( $offset, $value ) {
 	 *
 	 * @param mixed $offset The offset to unset.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetUnset( $offset ) {
 		unset( $this->callbacks[ $offset ] );
 	}
@@ -495,6 +499,7 @@ public function offsetUnset( $offset ) {
 	 *
 	 * @return array Of callbacks at current priority.
 	 */
+	#[ReturnTypeWillChange]
 	public function current() {
 		return current( $this->callbacks );
 	}
@@ -508,6 +513,7 @@ public function current() {
 	 *
 	 * @return array Of callbacks at next priority.
 	 */
+	#[ReturnTypeWillChange]
 	public function next() {
 		return next( $this->callbacks );
 	}
@@ -521,6 +527,7 @@ public function next() {
 	 *
 	 * @return mixed Returns current priority on success, or NULL on failure
 	 */
+	#[ReturnTypeWillChange]
 	public function key() {
 		return key( $this->callbacks );
 	}
@@ -534,6 +541,7 @@ public function key() {
 	 *
 	 * @return bool Whether the current position is valid.
 	 */
+	#[ReturnTypeWillChange]
 	public function valid() {
 		return key( $this->callbacks ) !== null;
 	}
@@ -545,6 +553,7 @@ public function valid() {
 	 *
 	 * @link https://www.php.net/manual/en/iterator.rewind.php
 	 */
+	#[ReturnTypeWillChange]
 	public function rewind() {
 		reset( $this->callbacks );
 	}