Why do I get “missing lifetime specifier” or “wrong number of type arguments” when implementing a trait for a struct?

Question

I\'m trying to define and implement a trait for a struct. All my implementations with generics and lifetime have problems. This must be a rookie mistake. What am I doing wro

Answer 1

The error messages seem pretty clear to me. They point at a type and state that the type needs a lifetime or a type. Add them:

impl<'a> Bar1<'a> for Foo1<'a> { /* ... */ }
impl<T> Bar2<T> for Foo2<T> { /* ... */ }
impl<'a, T: 'a> Bar3<'a, T> for Foo3<'a, T> { /* ... */ }

This is required because you've created parameterized traits:

pub trait Bar3<'a, T: 'a> {
//            ^^^^^^^^^^^
    fn baaar(&self);
}

None of the traits you have defined need any kind of generic parameters, so the "real" solution is just to remove them. I assume you've added them for some learning purpose not shown here though.