Using futur antérieur with a “quand” clause

Question

There is a question in my textbook that asks me to conjugate the verbs to either the futur simple or futur antérieur form, whichever is appropriate:

Je (dîner), quand il (revenir).

The correct answer was Je dînerai, quand il sera revenu (I will eat when he has returned).

However, I feel like J’aurai dîné, quand il reviendra (I will have eaten when he returns) works too. Is this ungrammatical? If so, could someone please explain?

I'm imagining a situation like:

— Tu veux dîner avec moi quand je reviens ?
— Non, j'aurai dîné quand tu reviendras.

Answer 1

Both « Je dînerai quand il sera revenu » and « Je dînerai quand il reviendra » are correct, meaningful French sentences. (We'd never put a comma here.) They have slightly different meanings: the first means that I will have dinner at some point after the time he comes back, the second means that I will have dinner as soon as he comes back. (“Have dinner” is somewhat imprecise; the second sentence works if I start eating as soon as he comes back, but also if I start cooking as soon as he comes back.)

If your textbook doesn't allow « Je dînerai quand il reviendra », it's wrong, unless there's context that implies that I won't be having dinner just when he comes back.

« J'aurai dîné quand il reviendra » and « J'aurai dîné quand il sera revenu » are also correct, but a bit awkward. The first sentence means that I will have finished dinner by the time he comes back. The second sentence is similar, but the reference time (when he comes back) is in the past relative to the main time of the action in the second sentence, whereas it's part of the main time of the action in the first sentence. I would use different phrasing: « J'aurai dîné d'ici à ce qu'il revienne » ou « J'aurai fini de dîner avant son retour ».

Answer 2

En français:

Le futur antérieur exprime l'antériorité par rapport à une action au futur. D'où la réponse correcte est:

Je dînerai, quand il sera revenu

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In English:

There are two actions in that sentence: dîner (to eat) and revenir (to return back).

Saying:

J’aurai dîné, quand il reviendra

means you will eat before he comes back.

So logically when he comes back you will eat.

Both actions belong to the future, however one of them (revenir) is preceding the other (dîner), thus the right answer is:

Je dînerai, quand il sera revenu

Remember of this:

Futur antérieur is closer to the present than futur simple