Trait object

test.rs

impl<'self> ToStr for ~std::to_str::ToStr
{
	fn to_str(&self) -> ~str
	{
		self.to_str();
	}
}

fn test<T : ToStr>(a : T)
{
	println(a.to_str());
}

fn main()
{
	let x = ~1i; let t = x as ~ToStr; test(t);
}

/*
test.rs:1:0: 7:1 error: cannot provide an extension implementation for a trait not defined in this crate
test.rs:1 impl<'self> ToStr for ~std::to_str::ToStr
test.rs:2 {
test.rs:3       fn to_str(&self) -> ~str
test.rs:4       {
test.rs:5               self.to_str();
test.rs:6       }
          ...
error: aborting due to previous error
*/