Cannot have the same supertrait twice, but with different type parameters

I am writing a Euclidean Vector class, and want to override some operations for it. However, when I try to add mul for both Vector-Vector multiplication and Vector-Scalar multiplication, the compiler complains that there is a Duplicate supertrait in trait declaration:

euclidean_vector.rs:5:0: 20:1 error: Duplicate supertrait in trait declaration
euclidean_vector.rs:5 pub trait EuclideanVector<T: Num + Algebraic> : 
euclidean_vector.rs:6   Add<Self, Self> +
euclidean_vector.rs:7   Sub<Self, Self> +
euclidean_vector.rs:8   Mul<Self, Self> +
euclidean_vector.rs:9   Mul<T, Self> +
euclidean_vector.rs:10   One + Zero +

@nikomatsakis

cc @nikomatsakis, does your current work also include this?

@nikomatsakis

On Mon, Apr 07, 2014 at 10:42:04AM -0700, Corey Richardson wrote:

cc @nikomatsakis, does your current work also include this?

Yes.

Actually that's not true. That portion of the work never landed.

e.g. this example still fails to compile:

trait Foo<T> { }

trait Bar : Foo<int> + Foo<uint> { }

fn main() { }

I think there are some subtle issues here that would have to be addressed eventually, particularly around object types.

I've wound up fixing this kind of by accident as part of another patch.

Auto merge of rust-lang#10596 - blyxyas:book-write_tests, r=flip1995

Merge rust-lang#10596

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Cannot have the same supertrait twice, but with different type parameters #10596

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Cannot have the same supertrait twice, but with different type parameters #10596

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emberian commented on Apr 7, 2014

nikomatsakis commented on Apr 9, 2014

nikomatsakis commented on Nov 3, 2014

nikomatsakis commented on Nov 3, 2014

nikomatsakis commented on Mar 3, 2015

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