wp-includes/class-wp-theme.php:1655Determines the latest WordPress default theme that is installed.
WP_Theme|false public static function get_core_default_theme() { foreach ( array_reverse( self::$default_themes ) as $slug => $name ) { $theme = wp_get_theme( $slug ); if ( $theme->exists() ) { return $theme; } } return false; }Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-theme.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.