Error code E0368

A binary assignment operator like += or ^= was applied to a type that doesn't support it.

Erroneous code example:

#![allow(unused)] fn main() { 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:

#![allow(unused)] fn main() { 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:

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.