wp-includes/class-wp-network.php:289Sets the site name assigned to the network if one has not been populated.
private function _set_site_name() { if ( ! empty( $this->site_name ) ) { return; } $default = ucfirst( $this->domain ); $this->site_name = get_network_option( $this->id, 'site_name', $default ); }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-network.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.