wp-includes/class-wp-theme.php:1156Returns the absolute path to the directory of a theme's "stylesheet" files.
string public function get_stylesheet_directory() { if ( $this->errors() && in_array( 'theme_root_missing', $this->errors()->get_error_codes(), true ) ) { return ''; } return $this->theme_root . '/' . $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.