I read about French passport renewals (Google Translate):
The old passport must be returned. If it included a visa, it can be kept for the period of validity of this visa.
How about visas that are e-visas (i.e., not appearing on the passport)? Must the old passport be returned if one has a valid e-visa using the old passport's number?
Original quote in French:
L'ancien passeport doit être restitué. S'il comportait un visa, il peut être conservé pendant la durée de validité de ce visa.