Explicit converting copy constructor from compatible basic_result. Calls void on_result_copy_construction(T *, U &&) noexcept with this and the input.

Requires: predicate::enable_compatible_conversion<R, S, P> is true.

Complexity: Same as for the copy constructors of the underlying types. Constexpr, triviality and noexcept of underlying operations is propagated.

Guarantees: If an exception is thrown during the operation, the object is left in a partially completed state, as per the normal rules for the same operation on a struct.