It's funny because it's doubly exponential WRT code size. However it's also almost linear (n log*(n) due to union-find) WRT the size of the type and sane humans don't write programs with huge types.
I don't know about Swift, but in Rust there are libraries like Diesel that essentially builds a new type out of the operations you run (in Diesel's case, it's used to type a SQL query), which may lead to huge types in ordinary code.
Programmers don't manually write those types however.
Programmers don't manually write those types however.