Article 23-9 of the French Civil Code
The loss of French nationality takes effect: 1° In the case provided for in article 23 at the date of acquisition of foreign nationality; 2° In the case provided for in Articles 23-3 and 23-5 on the date of the declaration; 3° In the case provided for in Articles 23-4, 23-7 and 23-8 on the date of the decree; 4° In the cases provided for in Article 23-6 on the…