resolve_block_template( string $template_type, string[] $template_hierarchy, string $fallback_template ): WP_Block_Template|null

153function resolve_block_template( $template_type, $template_hierarchy, $fallback_template ) {154	if ( ! $template_type ) {155		return null;156	}157 158	if ( empty( $template_hierarchy ) ) {159		$template_hierarchy = array( $template_type );160	}161 162	$slugs = array_map(163		'_strip_template_file_suffix',164		$template_hierarchy165	);166 167	// Find all potential templates 'wp_template' post matching the hierarchy.168	$query     = array(169		'slug__in' => $slugs,170	);171	$templates = get_block_templates( $query );172 173	// Order these templates per slug priority.174	// Build map of template slugs to their priority in the current hierarchy.175	$slug_priorities = array_flip( $slugs );176 177	usort(178		$templates,179		static function ( $template_a, $template_b ) use ( $slug_priorities ) {180			return $slug_priorities[ $template_a->slug ] - $slug_priorities[ $template_b->slug ];181		}182	);183 184	$theme_base_path        = get_stylesheet_directory() . DIRECTORY_SEPARATOR;185	$parent_theme_base_path = get_template_directory() . DIRECTORY_SEPARATOR;186 187	// Is the active theme a child theme, and is the PHP fallback template part of it?188	if (189		str_starts_with( $fallback_template, $theme_base_path ) &&190		! str_contains( $fallback_template, $parent_theme_base_path )191	) {192		$fallback_template_slug = substr(193			$fallback_template,194			// Starting position of slug.195			strpos( $fallback_template, $theme_base_path ) + strlen( $theme_base_path ),196			// Remove '.php' suffix.197			-4198		);199 200		// Is our candidate block template's slug identical to our PHP fallback template's?201		if (202			count( $templates ) &&203			$fallback_template_slug === $templates[0]->slug &&204			'theme' === $templates[0]->source205		) {206			// Unfortunately, we cannot trust $templates[0]->theme, since it will always207			// be set to the active theme's slug by _build_block_template_result_from_file(),208			// even if the block template is really coming from the active theme's parent.209			// (The reason for this is that we want it to be associated with the active theme210			// -- not its parent -- once we edit it and store it to the DB as a wp_template CPT.)211			// Instead, we use _get_block_template_file() to locate the block template file.212			$template_file = _get_block_template_file( 'wp_template', $fallback_template_slug );213			if ( $template_file && get_template() === $template_file['theme'] ) {214				// The block template is part of the parent theme, so we215				// have to give precedence to the child theme's PHP template.216				array_shift( $templates );217			}218		}219	}220 221	return count( $templates ) ? $templates[0] : null;222}