blob: 7b9d93348213120a555931a5139a7c235c393338 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
A binary assignment operator like `+=` or `^=` was applied to a type that
doesn't support it.
Erroneous code example:
```compile_fail,E0368
let mut x = 12f32; // error: binary operation `<<` cannot be applied to
// type `f32`
x <<= 2;
```
To fix this error, please check that this type implements this binary
operation. Example:
```
let mut x = 12u32; // the `u32` type does implement the `ShlAssign` trait
x <<= 2; // ok!
```
It is also possible to overload most operators for your own type by
implementing the `[OP]Assign` traits from `std::ops`.
Another problem you might be facing is this: suppose you've overloaded the `+`
operator for some type `Foo` by implementing the `std::ops::Add` trait for
`Foo`, but you find that using `+=` does not work, as in this example:
```compile_fail,E0368
use std::ops::Add;
struct Foo(u32);
impl Add for Foo {
type Output = Foo;
fn add(self, rhs: Foo) -> Foo {
Foo(self.0 + rhs.0)
}
}
fn main() {
let mut x: Foo = Foo(5);
x += Foo(7); // error, `+= cannot be applied to the type `Foo`
}
```
This is because `AddAssign` is not automatically implemented, so you need to
manually implement it for your type.
|
