Why does an overloaded assignment operator not get inherited? [duplicate]

Answer 1

You are forgetting the methods that the compiler automatically generates if they are not declared. Assignment is amongst them.

Answer 2

Class Y contains implicitly-declared assignment operators, which hide the operator declared in the base class. In general, declaring a function in a derived class hides any function with the same name declared in a base class.

If you want to make both available in Y, use a using-declaration:

class Y : public X {
public:
    using X::operator=;
};