facadetemplate <class F>
concept facade = /* see-below */;
The concept facade<F> specifies that a type F models a facade of proxy. If F depends on an incomplete type, and its evaluation could yield a different result if that type were hypothetically completed, the behavior is undefined. facade<F> is true when F meets the ProBasicFacade requirements; otherwise, it is false.
Note that concept facade does not impose strong constraints on the dependent convention and reflection types. It is recommended to use facade_builder to define a facade type that models concept facade.