Find free function that has been shadowed by a member function

March 24, 2024

How can I find a free function that has been shadowed by a member function in a class.

namespace some_namespace
{
    struct the_type{};
    void function(the_type);
}

namespace other_namespace
{
    template<class T>
    class my_wrapper
    {
    public:
        void function()
        { function(m_value); }
    private:
        T m_value;
    }
};

Here, I do not know in what namespace to look, so I cannot use any qualification. The implementation is expected to be found by ADL. Is the only way to escape the class by adding a wrapper function outside the class with a different name?

Why class member functions shadow free functions with same name?

Answers why it is like it is, but does not suggest what the canonical workaround is.

>Solution :

The reason ADL fails^† is because unqualified lookup finds my_wrapper::function. So we shadow that by bringing a dummy free function into scope.

namespace some_namespace
{
    struct the_type{};
    void function(the_type);
}

namespace other_namespace
{
    struct dummy {};
    void function(dummy);

    template<class T>
    class my_wrapper
    {
    public:
        void function()
        {
            using other_namespace::function;
            function(m_value);
        }
    private:
        T m_value;
    };
}

_{† Actually, no ADL is performed.}