[rustc.git] / src / librustc_error_codes / error_codes / E0276.md

A trait implementation has stricter requirements than the trait definition.

Erroneous code example:

```compile_fail,E0276
trait Foo {
    fn foo<T>(x: T);
}

impl Foo for bool {
    fn foo<T>(x: T) where T: Copy {}
}
```

Here, all types implementing `Foo` must have a method `foo<T>(x: T)` which can
take any type `T`. However, in the `impl` for `bool`, we have added an extra
bound that `T` is `Copy`, which isn't compatible with the original trait.

Consider removing the bound from the method or adding the bound to the original
method definition in the trait.
Commit	Line	Data
74b04a01 XL	1	A trait implementation has stricter requirements than the trait definition.
	2
	3	Erroneous code example:
60c5eb7d XL	4
	5	```compile_fail,E0276
	6	trait Foo {
	7	fn foo<T>(x: T);
	8	}
	9
	10	impl Foo for bool {
	11	fn foo<T>(x: T) where T: Copy {}
	12	}
	13	```
	14
	15	Here, all types implementing `Foo` must have a method `foo<T>(x: T)` which can
	16	take any type `T`. However, in the `impl` for `bool`, we have added an extra
	17	bound that `T` is `Copy`, which isn't compatible with the original trait.
	18
	19	Consider removing the bound from the method or adding the bound to the original
	20	method definition in the trait.