39 lines
714 B
Rust
39 lines
714 B
Rust
|
#[derive(Debug)]
|
||
|
|
struct X<T>(T);
|
||
|
|
|
||
|
|
impl<T: Clone> Clone for X<T> {
|
||
|
|
fn clone(&self) -> X<T> {
|
||
|
|
X(self.0.clone())
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#[derive(Debug)]
|
||
|
|
struct Y;
|
||
|
|
|
||
|
|
#[derive(Debug)]
|
||
|
|
struct Str {
|
||
|
|
x: Option<i32>,
|
||
|
|
}
|
||
|
|
|
||
|
|
fn foo(s: &mut Option<i32>) {
|
||
|
|
if s.is_none() {
|
||
|
|
*s = Some(0);
|
||
|
|
}
|
||
|
|
println!("{:?}", s);
|
||
|
|
}
|
||
|
|
|
||
|
|
fn bar<T: std::fmt::Debug>(s: &mut X<T>) {
|
||
|
|
println!("{:?}", s);
|
||
|
|
}
|
||
|
|
fn main() {
|
||
|
|
let s = Str { x: None };
|
||
|
|
let sr = &s;
|
||
|
|
let mut sm = sr.clone();
|
||
|
|
foo(&mut sm.x); //~ ERROR cannot borrow `sm.x` as mutable, as it is behind a `&` reference
|
||
|
|
|
||
|
|
let x = X(Y);
|
||
|
|
let xr = &x;
|
||
|
|
let mut xm = xr.clone();
|
||
|
|
bar(&mut xm); //~ ERROR cannot borrow data in a `&` reference as mutable
|
||
|
|
}
|