Strange blanket impl error

[dylanmckay]

When blanket impl'ing all types which implement a trait over the standard operators (in this case Add), we get the error:

error: cannot provide an extension implementation where both trait and type are not defined in this crate

error: conflicting implementations for trait `core::ops::Add`
note: conflicting implementation in crate `std`
error: conflicting implementations for trait `core::ops::Add`
note: conflicting implementation in crate `core`
error: conflicting implementations for trait `core::ops::Add`
note: conflicting implementation in crate `core`
...

The error is observed in the following Rust code (Playpen):

trait Vector<T: Add<T,T>>
{
    fn map_in_place(&mut self, f: |T| -> T);
}

impl<T: Add<T,T>, V: Vector<T>> Add<V,V> for V
{
    fn add(&self, rhs: &V) -> V
    {
        unimplemented!();
    }
}

fn main() { }

[frewsxcv]

I updated the code to compile with 1.1:

use std::ops::Add;

trait Vector<T: Add<T>> {
    fn map_in_place(&mut self, f: (Fn(T) -> T));
}

impl<T: Add<T>, V: Vector<T>> Add<V> for V {
    fn add(&self, rhs: &V) -> V {
        unimplemented!();
    }
}

fn main() { }

Playpen: http://is.gd/kEYfDA

<anon>:7:6: 7:7 error: the type parameter `T` is not constrained by the impl trait, self type, or predicates [E0207]
<anon>:7 impl<T: Add<T>, V: Vector<T>> Add<V> for V {
              ^

The error seems less obscure now, so it might be okay to close this?

[alexcrichton]

Thanks @frewsxcv!