When are numeric literals assigned to default types?

Question

I played with some code and made the following observation:

let x = 1;
let () = x;

error: mismatched types [E0308]
note:  expected type `_`
note:     found type `()`

This obviously fails, but I expected the error to indicate that the expected type was i32, and not _. I found that the same thing happens with a floating literal of indefinite type, for example. 1.0.

Why is that? Should the type already be known as the default?

Update : from the point of view of Rust 1.12, the error message is more informative:

expected integral variable, found ()

= note: expected type `{integer}`
= note:    found type `()`

Answer 1

Rust , . , , , , .

, let () = x; . x , , , x . , (), , x, , , x .