basic_facade_builder::support_copytemplate <constraint_level CL>
using support_copy = basic_facade_builder</* see below */>;
The alias template support_copy of basic_facade_builder<Cs, Rs, C> adds copyability support to the template parameters, specifically C::copyability. After the operation, C::copyability becomes std::max(C::copyability, CL).
If no copyability support is applied before specifying build, the default value of build::constraints.copyability is pro::constraint_level::none.
#include <memory>
#include "proxy.h"
struct Movable : pro::facade_builder::build {};
struct Copyable : pro::facade_builder
::support_copy<pro::constraint_level::nontrivial>
::build {};
int main() {
pro::proxy<Movable> p1 = std::make_unique<int>(123);
// pro::proxy<Copyable> p2 = std::make_unique<int>(123); // Won't compile
pro::proxy<Copyable> p3 = std::make_shared<int>(456);
// auto p4 = p1; // Won't compile
auto p5 = p3;
}