This gives me a "not a trait"-error for MyRequiredStruct.
MyRequiredStruct provides some implementation for all T: Default + Clone. MyRequiredTrait is only implemented for some special Ts. SomeStruct has to call methods of both implementations. My assumption was that a struct has some kind of inherent interface that can be used like a trait.
I assumed the left-hand statement of a where had to be a newly introduced identifier, so I just did't try that. I now understand the the where-clause is just a set of rules and not a set of declarations.