How do I fix E0369 (binary operation cannot be applied to type)?

Derive or implement the operator trait: Build a String:

Rust errors / Types and traits

Rust compiler error · checked with rustc 1.99.0

Rust error E0369: binary operation cannot be applied to type

Q: What does Rust error E0369 mean?

An operator like + or == was used on a type that does not implement it.

What it meansAn operator like + or == was used on a type that does not implement it.

What rustc prints

error[E0369]: no implementation for `f32 << {integer}`
 --> main.rs:6:3
  |
6 | x << 2;
  | - ^^ - {integer}
  | |
  | f32

Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.

Why it happens

Comparing structs with == without #[derive(PartialEq)].
Adding two &str values (use format! or a String).

How to fix it

1. Derive or implement the operator trait

#[derive(PartialEq)]
struct Id(u32);

2. Build a String

let full = format!("{first} {last}");

Other wordings of this error

binary operation cannot be applied to type, cannot be applied to type, no implementation for

E0369Types and traits

Activein rustc 1.99.0

8related errors linked below

The compiler team's explanation

A binary operation was attempted on a type which doesn't support it.

Erroneous code example:

let 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 x = 12u32; // the `u32` type does implement it:
               // https://doc.rust-lang.org/stable/std/ops/trait.Shl.html

x << 2; // ok!

It is also possible to overload most operators for your own type by implementing traits from std::ops.

String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left. If something should be added to a string literal, move the literal to the heap by allocating it with to_owned() like in "Your text".to_owned().

From rustc --explain E0369 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.

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Often hit nextE0308: mismatched typesA related error from the same family.Read it next →

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