Have std::string::ToString for X automatically provide std::convert::From<X> for String

[mqudsi]

Is there a good reason the following can't be done?

impl<T> std::convert::From<T> for std::string::String where T: std::string::ToString {
    fn from(t: T) -> Self {
        t.to_string()
    }

The only thing I can think of is if the value of T converted to String has a different meaning of the value of T.display() (as that's where a lot of the ToString implementations are coming from) such that you might want different behavior there.

Being able to do something like s: String = 42.into() anywhere would be nice.

[jonas-schievink]

There's already impl ToString for String which conflicts with the reflexive From<T> for T impl.