wp-includes/class-wp-theme.php:1136Returns the directory name of the theme's "stylesheet" files, inside the theme root.
string public function get_stylesheet() { return $this->stylesheet; }Introduced in 3.4.0. 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.