HTML5 script support is always true

[sirreal]

Since non-HTML5 script output was completely removed in r61415, all scripts are now output as HTML5. This change makes the theme support check reflect that reality by always returning true for script support, regardless of whether themes explicitly declare support.

The behavior of add_theme_support() and remove_theme_support() remains unchanged.
Only the check via current_theme_supports( 'html5', 'script' ) is affected.

Theme REST API calls to remain unchanged:

(await wp.apiFetch({path: '/wp/v2/themes?status=active' }))[0].theme_supports.html5
// ['comment-form', 'comment-list', 'search-form', 'gallery', 'caption', 'style', 'script']

get_theme_support() behavior is unchanged at this time so current_theme_supports() may be incoherent. Additionally if no html5 support is enabled for a theme, script support remains false. REST API theme response inherits this strange behavior because it relies on both get_theme_support() and current_theme_supports(). Details in #10919 (comment).

Trac ticket: https://core.trac.wordpress.org/ticket/64442

Use of AI Tools

The basic implementation was performed by Claude Code. I performed full review and adaptation of the changes.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[sirreal]

Suggested change

// HTML5 script support is always enabled since non-HTML5 script output was removed in 7.0.

[github-actions]

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[sirreal]

This turns out to be messier than expected, largely because get_theme_support() and current_theme_supports() are both theme support lookup functions, but they both rely directly on the global $_wp_theme_features.

I think the cleanest way to implement this is to have current_theme_supports() rely on get_theme_support() and remove its use of the global. get_theme_support() can then be responsible for always declaring that 'html', 'script' support is enabled.

wordpress-develop/src/wp-includes/theme.php

Lines 3030 to 3050 in d3b793f

	function get_theme_support( $feature, ...$args ) {
	global $_wp_theme_features;
	if ( ! isset( $_wp_theme_features[ $feature ] ) ) {
	return false;
	}
	if ( ! $args ) {
	return $_wp_theme_features[ $feature ];
	}
	switch ( $feature ) {
	case 'custom-logo':
	case 'custom-header':
	case 'custom-background':
	return $_wp_theme_features[ $feature ][0][ $args[0] ] ?? false;
	default:
	return $_wp_theme_features[ $feature ];
	}
	}

wordpress-develop/src/wp-includes/theme.php

Lines 3157 to 3203 in d3b793f

	function current_theme_supports( $feature, ...$args ) {
	global $_wp_theme_features;
	if ( 'custom-header-uploads' === $feature ) {
	return current_theme_supports( 'custom-header', 'uploads' );
	}
	if ( ! isset( $_wp_theme_features[ $feature ] ) ) {
	return false;
	}
	// If no args passed then no extra checks need to be performed.
	if ( ! $args ) {
	/** This filter is documented in wp-includes/theme.php */
	return apply_filters( "current_theme_supports-{$feature}", true, $args, $_wp_theme_features[ $feature ] ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
	}
	switch ( $feature ) {
	case 'post-thumbnails':
	/*
	* post-thumbnails can be registered for only certain content/post types
	* by passing an array of types to add_theme_support().
	* If no array was passed, then any type is accepted.
	*/
	if ( true === $_wp_theme_features[ $feature ] ) { // Registered for all types.
	return true;
	}
	$content_type = $args[0];
	return in_array( $content_type, $_wp_theme_features[ $feature ][0], true );
	case 'html5':
	case 'post-formats':
	/*
	* Specific post formats can be registered by passing an array of types
	* to add_theme_support().
	*
	* Specific areas of HTML5 support *must* be passed via an array to add_theme_support().
	*/
	$type = $args[0];
	return in_array( $type, $_wp_theme_features[ $feature ][0], true );
	case 'custom-logo':
	case 'custom-header':
	case 'custom-background':
	// Specific capabilities can be registered by passing an array to add_theme_support().
	return ( isset( $_wp_theme_features[ $feature ][0][ $args[0] ] ) && $_wp_theme_features[ $feature ][0][ $args[0] ] );
	}

wordpress-develop/src/wp-includes/rest-api/endpoints/class-wp-rest-themes-controller.php

Lines 296 to 329 in d3b793f

	if ( rest_is_field_included( 'theme_supports', $fields ) && $this->is_same_theme( $theme, $current_theme ) ) {
	foreach ( get_registered_theme_features() as $feature => $config ) {
	if ( ! is_array( $config['show_in_rest'] ) ) {
	continue;
	}
	$name = $config['show_in_rest']['name'];
	if ( ! rest_is_field_included( "theme_supports.{$name}", $fields ) ) {
	continue;
	}
	if ( ! current_theme_supports( $feature ) ) {
	$data['theme_supports'][ $name ] = $config['show_in_rest']['schema']['default'];
	continue;
	}
	$support = get_theme_support( $feature );
	if ( isset( $config['show_in_rest']['prepare_callback'] ) ) {
	$prepare = $config['show_in_rest']['prepare_callback'];
	} else {
	$prepare = array( $this, 'prepare_theme_support' );
	}
	$prepared = $prepare( $support, $config, $feature, $request );
	if ( is_wp_error( $prepared ) ) {
	continue;
	}
	$data['theme_supports'][ $name ] = $prepared;
	}
	}

The alternative is to leave this as is (close this PR without landing). These checks are infrequent in plugins. get_theme_support( 'html5' ) in particular is very minimal.