why auto doesn't detect reference type of function

Question

I made a class with method, which returns reference to member (not good encapsulation). I'm using auto for retuned funtion

class classA
{
    public:
    classA(classA & rhs)
    {
        cout<<"copy constr A"<<endl;
    };
    classA() = default;
};

class classB
{
    private:
    classA obA;
    public:
        classA& getRefA(){return obA;}
};

int main()
{
    classB obB;

    auto ob = obB.getRefA();
 }

The result is copy constr A

I understand that auto don't detect reference from function. Is auto detecting only the type without reference?

Answer 1

auto just by itself doesn't infer reference types. You can use auto& if you explicitly need a lvalue reference, or auto&& to use the reference collapsing rules for type inference.

If you need the type of an expression, use decltype. Keep in mind that there is a difference between decltype(x) and decltype((x)) -- the latter preserves references.

More resources on that topic:

• Universal References in C++11
• use of rvalue reference and auto
• In C++, what expressions yield a reference type when decltype is applied to them?

Answer 2

The short answer is because auto doesn't capture any reference. It also won't capture cv-qualifiers.

If you need this behavior, you should use decltype.