1 // RFC 736 (and Issue 21407): functional struct update should respect privacy.
3 // The `foo` module attempts to maintains an invariant that each `S`
4 // has a unique `u64` id.
7 use std::cell::{UnsafeCell};
9 static mut COUNT : UnsafeCell<u64> = UnsafeCell::new(1);
11 pub struct S { pub a: u8, pub b: String, secret_uid: u64 }
13 pub fn make_secrets(a: u8, b: String) -> S {
14 let val = unsafe { let p = COUNT.get(); let val = *p; *p = val + 1; val };
15 println!("creating {}, uid {}", b, val);
16 S { a: a, b: b, secret_uid: val }
21 println!("dropping {}, uid {}", self.b, self.secret_uid);
27 let s_1 = foo::make_secrets(3, format!("ess one"));
28 let s_2 = foo::S { b: format!("ess two"), ..s_1 }; // FRU ...
29 //~^ ERROR field `secret_uid` of struct `S` is private
30 println!("main forged an S named: {}", s_2.b);
31 // at end of scope, ... both s_1 *and* s_2 get dropped. Boom!