How do I understand two-phase lookup?

In C++, two-phase lookup is a mechanism that involves two distinct phases during name resolution. This is primarily used in the context of template instantiation. The first phase looks up the names in the scope, while the second phase rechecks all the names after the template is instantiated. This allows for more flexible and powerful template programming, giving the compiler the ability to resolve names at different stages.

        template
        void func() {
            T::member; // First phase lookup
        }

        struct A {
            static void member() {}
        };

        void example() {
            func(); // Second phase lookup, where "A::member" is resolved
        }