Generic struct with where, why does it need the where on impls?

help
1

If I have a generic struct:

pub struct AStruct<T>
where
    T: MyTrait
{
    field: T
}

And I implement some OtherTrait on it, why does the impl also require a where T: MyTrait?

Ex. this won't work:

impl OtherTrait for AStruct<T> {}

Has to be:

impl OtherTrait for AStruct<T> 
where T: MyTrait 
{}

If the struct can only be made with a type that implements MyTrait, why do I need to put a bunch of extra where clauses on all the impl?

2

RFC 2089 proposes no longer requiring those bounds on the impl. The RFC was accepted and the implementation is being tracked in rust-lang/rust#44491.

2 Likes
3

Ah, well then yay. :slight_smile: