Question

I have overloaded methods:

    template<typename AnyType>
    void AnyFunc(AnyType &t);

    template<typename AnyType>
    void AnyFunc(AnyType &&t);

I have a caller which holds a pointer and want to use one of the functions:

    MyType* ptr=new MyType();
    AnyFunc(*ptr);

The last line runs into compile error: ambiguous overload for AnyFunc

How can I select the function I need? The simple case is to use:

    AnyFunc(std::move(*ptr)); 

which select the void AnyFunc(AnyType &&t); but this is not what I want. I need the
void AnyFunc(AnyType &t); method.

Answer 1

Any time you have T&& v (where T is a template parameter), you have a so-called universal reference. Not only does it bind to rvalues, but also to lvalues. It’s a greedy template. It will take anything it can get and give nothing back.

Overloading when a greedy template is involved is a bad idea, unless you know exactly what you’re doing.

With universal references, there’s often no need to special-case lvalues vs rvalues. Just std::forward<T>(v) the parameter and the value category will be propagated.