drop support for PHP 4 in favor of PHP 7+ native types

Author: kkmuffme

src/wp-includes/plugin.php

@@ -507,11 +507,8 @@ function do_action( $hook_name, ...$arg ) {
 		$wp_current_filter[] = $hook_name;
 	}
 
-	if ( empty( $arg ) ) {
+	if ( array() === $arg ) {
 		$arg[] = '';
-	} elseif ( is_array( $arg[0] ) && 1 === count( $arg[0] ) && isset( $arg[0][0] ) && is_object( $arg[0][0] ) ) {
-		// Backward compatibility for PHP4-style passing of `array( &$this )` as action `$arg`.
-		$arg[0] = $arg[0][0];
 	}
 
 	$wp_filter[ $hook_name ]->do_action( $arg );

tests/phpunit/includes/utils.php

@@ -133,6 +133,26 @@ public function action2( $arg ) {
 		return $arg;
 	}
 
+	/**
+	 * @since 6.6.0
+	 */
+	public function action3( array $arg ) {
+		$current_filter = $this->current_filter();
+
+		if ( $this->debug ) {
+			dmp( __FUNCTION__, $current_filter );
+		}
+
+		$this->events[] = array(
+			'action'    => __FUNCTION__,
+			'hook_name' => $current_filter,
+			'tag'       => $current_filter, // Back compat.
+			'args'      => func_get_args(),
+		);
+
+		return $arg;
+	}
+
 	/**
 	 * @since UT (3.7.0)
 	 */

tests/phpunit/tests/actions.php

@@ -96,6 +96,24 @@ public function test_has_action() {
 		$this->assertFalse( has_action( $hook_name ) );
 	}
 
+	/**
+	 * One tag with array with 1 object to ensure it will stay an array and not become an object
+	 *
+	 * @covers ::do_action
+	 */
+	public function test_action_args_1() {
+		$a         = new MockAction();
+		$hook_name = __FUNCTION__;
+		$val       = new stdClass();
+
+		add_action( $hook_name, array( $a, 'action3' ) );
+		do_action( $hook_name, array( $val ) );
+
+		$call_count = $a->get_call_count();
+		$argsvar    = $a->get_args();
+		$this->assertSame( array( $val ), array_pop( $argsvar ) );
+	}
+
 	/**
 	 * One tag with multiple actions.
 	 *