Tell compiler to implement trait on certain types only

[MarkNeuhaus]

Is there a way to restrict the implementation of a trait to types only, that have implemented another trait?

[alice]

This implements TraitBar for everything that implements TraitFoo:

impl<T: TraitFoo> TraitBar for T {
    ...
}

[MarkNeuhaus]

That one I'm aware of. What I have in mind is the other way around. A way to tell the compiler to not allow implementation on types that don't have a certrain trait implemented

[alice]

You can define the trait like this:

trait TraitBar: TraitFoo {
    ...
}