Why can't we derive struct's?

[Steven Schveighoffer]

On 12/21/18 5:23 PM, Steven Schveighoffer wrote:
> 1. The type's members or base classes
> 2. The type's alias this'd members. Any ambiguities are a compiler error.
> 3. UFCS functions that accept the type or base classes.
> 4. UFCS functions that accept any alias this'd type. Any ambiguities are 
> a compiler error.

A simple way to put this is -- if the code would compile WITHOUT alias 
this, then that's what happens.

-Steve