The Almighty God decrees:
“Oh you who believe! Intoxicants, gambling, idols, arrows for seeking the future or luck are all abominations, the work of the Devil. So, keep away from them that you may attain what you hope for. The Devil only desires to create grudge and hostility between you with intoxicants and gambling; and prevent you from the sound information of God (the Quran) and the prayers. Will you, now, desist?” (Al-Ma’ida/ The Feast 5:90-91)
As you can see, intoxicants are forbidden in the verse and keeping the distance with them is required because of the command “Keep away from them!”. According to this, the Messenger of Allah said:
Narrated by Anas ibn Malik:
“The Messenger of Allah (pbuh) cursed ten involved in intoxicants: The one who produces it, the one who has it produced, its drinker, its carrier, and the one it is carried to, its server, its trader, consumption of the income from it, the one who purchases it and the one it was purchased for.” (Tirmidhi, Buyu, 59)
A person who eats in a place where alcohol is served is not included in any of these groups, so it is permissible.
Yet, it would be an extra good deed to choose another place in order to put a distance between you and alcohol.