WP_Query::is_post_type_archive( string|string[] $post_types = '' )

	public function is_post_type_archive( $post_types = '' ) {
		if ( empty( $post_types ) || ! $this->is_post_type_archive )
			return (bool) $this->is_post_type_archive;

		$post_type = $this->get( 'post_type' );
		if ( is_array( $post_type ) )
			$post_type = reset( $post_type );
		$post_type_object = get_post_type_object( $post_type );

		return in_array( $post_type_object->name, (array) $post_types );
	}