Does anyone know the story about an astronaut stranded on an alien planet who discovers an alien habitat or some sort, that slowly transforms him into an alien being in order to survive its toxic atmosphere and to enable him to take in the alien food?
This is likely van Vogt's Enchanted Village.
The lone survivor of a ship crashed on Mars encounters a living city that tries to please him but is unsuited to his needs. The music is oppressive and clamorous, the shower delivers an acid bath. With each drop of water it provides, a bit of the city disintegrates. The man tries to commit suicide, reasoning that his fate is sealed and there is no need for the city to destroy itself. During the night, it seems the city adjusts. The man wakes up to a delicious meal, violin music, and a proper bed temperature.
He waddles off happily, unperturbed by his new snout and four-foot tail.