add_theme_support( string $feature, mixed $args ): void|false

2690function add_theme_support( $feature, ...$args ) {2691	global $_wp_theme_features;2692 2693	if ( ! $args ) {2694		$args = true;2695	}2696 2697	switch ( $feature ) {2698		case 'post-thumbnails':2699			// All post types are already supported.2700			if ( true === get_theme_support( 'post-thumbnails' ) ) {2701				return;2702			}2703 2704			/*2705			 * Merge post types with any that already declared their support2706			 * for post thumbnails.2707			 */2708			if ( isset( $args[0] ) && is_array( $args[0] ) && isset( $_wp_theme_features['post-thumbnails'] ) ) {2709				$args[0] = array_unique( array_merge( $_wp_theme_features['post-thumbnails'][0], $args[0] ) );2710			}2711 2712			break;2713 2714		case 'post-formats':2715			if ( isset( $args[0] ) && is_array( $args[0] ) ) {2716				$post_formats = get_post_format_slugs();2717				unset( $post_formats['standard'] );2718 2719				$args[0] = array_intersect( $args[0], array_keys( $post_formats ) );2720			} else {2721				_doing_it_wrong(2722					"add_theme_support( 'post-formats' )",2723					__( 'You need to pass an array of post formats.' ),2724					'5.6.0'2725				);2726				return false;2727			}2728			break;2729 2730		case 'html5':2731			// You can't just pass 'html5', you need to pass an array of types.2732			if ( empty( $args[0] ) || ! is_array( $args[0] ) ) {2733				_doing_it_wrong(2734					"add_theme_support( 'html5' )",2735					__( 'You need to pass an array of types.' ),2736					'3.6.1'2737				);2738 2739				if ( ! empty( $args[0] ) && ! is_array( $args[0] ) ) {2740					return false;2741				}2742 2743				// Build an array of types for back-compat.2744				$args = array( 0 => array( 'comment-list', 'comment-form', 'search-form' ) );2745			}2746 2747			// Calling 'html5' again merges, rather than overwrites.2748			if ( isset( $_wp_theme_features['html5'] ) ) {2749				$args[0] = array_merge( $_wp_theme_features['html5'][0], $args[0] );2750			}2751			break;2752 2753		case 'custom-logo':2754			if ( true === $args ) {2755				$args = array( 0 => array() );2756			}2757			$defaults = array(2758				'width'                => null,2759				'height'               => null,2760				'flex-width'           => false,2761				'flex-height'          => false,2762				'header-text'          => '',2763				'unlink-homepage-logo' => false,2764			);2765			$args[0]  = wp_parse_args( array_intersect_key( $args[0], $defaults ), $defaults );2766 2767			// Allow full flexibility if no size is specified.2768			if ( is_null( $args[0]['width'] ) && is_null( $args[0]['height'] ) ) {2769				$args[0]['flex-width']  = true;