rust/tests/ui/traits/resolution-in-overloaded-op.rs

// #12402 Operator overloading only considers the method name, not which trait is implemented

trait MyMul<Rhs, Res> {
    fn mul(&self, rhs: &Rhs) -> Res;
}

fn foo<T: MyMul<f64, f64>>(a: &T, b: f64) -> f64 {
    a * b //~ ERROR cannot multiply `&T` by `f64`
}

fn main() {}
Use only the appropriate trait when looking up operator overloads. 2014-02-24 08:33:50 +00:00			`// #12402 Operator overloading only considers the method name, not which trait is implemented`

			`trait MyMul<Rhs, Res> {`
			`fn mul(&self, rhs: &Rhs) -> Res;`
			`}`

			`fn foo<T: MyMul<f64, f64>>(a: &T, b: f64) -> f64 {`
Improve wording of "cannot multiply" type error For example, if you had this code: fn foo(x: i32, y: f32) -> f32 { x * y } You would get this error: error[E0277]: cannot multiply `f32` to `i32` --> src/lib.rs:2:7 \| 2 \| x * y \| ^ no implementation for `i32 * f32` \| = help: the trait `Mul<f32>` is not implemented for `i32` However, that's not usually how people describe multiplication. People usually describe multiplication like how the division error words it: error[E0277]: cannot divide `i32` by `f32` --> src/lib.rs:2:7 \| 2 \| x / y \| ^ no implementation for `i32 / f32` \| = help: the trait `Div<f32>` is not implemented for `i32` So that's what this change does. It changes this: error[E0277]: cannot multiply `f32` to `i32` --> src/lib.rs:2:7 \| 2 \| x * y \| ^ no implementation for `i32 * f32` \| = help: the trait `Mul<f32>` is not implemented for `i32` To this: error[E0277]: cannot multiply `i32` by `f32` --> src/lib.rs:2:7 \| 2 \| x * y \| ^ no implementation for `i32 * f32` \| = help: the trait `Mul<f32>` is not implemented for `i32` 2020-10-18 02:59:51 +00:00			a * b //~ ERROR cannot multiply `&T` by `f64`
Use only the appropriate trait when looking up operator overloads. 2014-02-24 08:33:50 +00:00			`}`

			`fn main() {}`