//ww:run
package main;
type s = struct { a: i64, b: i32 };
type box = struct { v: s };
fn mk() box = { return box { v = s { a = 0i64, b = 0i32 } }; };
fn main() i32 = {
    let b: box = mk();
    b.v = s { a = 5i64, ... };
    return b.v.b;
};