Does Base_subobject also needs access specifier?

[GorNishanov]

Consider:

struct A {};
struct B {};

struct C : protected B, private A {};

Prior to introduction of subobjects, base_type was a declaration that had DeclSpecifiers that could encode both AccessProtection and virtual-ness of the base:

   enum class DeclSpecifiers : std::uint32_t {
       ...
      Virtual    = 1 << 6,   // also used as storage class specifier
                             // for virtual base subobjects
       ...
      Public     = 1 << 11,
      Protected  = 1 << 12,
      Private    = 1 << 13,
      AccessProtection = Public | Protected | Private,
       ...
   };

Looking at current definition of Base_subobject:

   // Specifier of semantics for base-class subobjects.
   enum class Subobject_specifier : std::uint8_t {
      Exclusive,                    // Each subobject is unshared, default in ISO C++
      Shared,                       // "virtual" subobject shared along inheritance chain
   };

                                // -- Base_subobject --
   // Each base-specifier in a base-clause morally declares an unnamed subobject.
   struct Base_subobject {
      virtual const Type& type() const = 0;
      virtual Subobject_specifier specifier() const = 0;
   };

it seems that we may have lost an ability to encode access protection for bases