The question is on the text as highlighted in this passage from chapter 5 of La porte étroite by André Gide.
La crainte de t’inquiéter ne me laisse pas te dire combien je t’attends, m’écrivait-elle vers la fin de l’été. Chaque jour à passer avant de te revoir pèse sur moi, m’oppresse.
Is jour à passer a set phrase or a model I can use for any noun and verb?
If the latter, I would be able to use the "noun + à + verb" form for any noun and verb combination so long as it make sense.
For example, because we can say,
Je vois un film
that gives us,
un film à voir
a movie to watch.
Similarly, you can generate the French equivalent of things to say, dogs to feed, people to visit etc. all on the same model.
Or the model is restricted in its availability somehow. The extreme case of this would be jour à passer as a set phase.
I am reminded of de quoi vivre, which doesn't seem to extend itself to just any verb.