Not exactly the same thing but this is still pretty funny. This is code that is technically 100% legal Rust but you should definitely never write such code 😅.
It's a test for the compiler which ensures that these legal yet extremely weird expressions continue to compile as the compiler is updated. So there is a purpose to the madness but it does still look pretty funny.
That makes complete sense. Ranges implement fmt::Debug, .. is a range, in particular the full range (all values) ..= isn't because the upper bound is missing but ..=.. ranges from the beginning to the... full range. Which doesn't make sense semantically but you can debug print it so add a couple more nested calls and you get a punch card.
I totally didn't need the Rust playground to figure that out.
EDIT: Oh, glossed over that: .. is only the full range if standing alone, it's also an infix operator which is why you can add as many as you want (be careful with whitespace, though). .. .. .. .. .. .. .. .. .. .. is a valid Rust expression.