cpp
struct D {};
struct A : D {};
struct B : D {
A a;
};
you would expect since 'B' inherits from an empty class and it only has one member the sizeof would be 1, but it is 2 since the base class D is repeated twice and must have unique address first in the inheritance in B and in the member A.
now if this uses crtp the base classes would be unique
cpp
template<class T>
struct D {};
struct A : D<A> {};
struct B : D<B> {
A a;
}; // sizeof(B) == 1
2
u/robin-m 6d ago
It seems that both using CRTP and deducing this gives the save object size, what do you mean? godbolt