Question

Is it possible to prevent a C++ template being used without specialization?

For example, I have

template<class T>
void foo() {}

And I don’t want it to be used without being specialized for foo<int> or foo<char>.

Answer 1

You should be able to declare the function without actually defining it in the generic case. This will cause a reference to an unspecialized template to emit an Undefined Symbol linker error.

template<class T>
void foo();

template<>
void foo<int>() {
    // do something here
}

This works just fine for me with clang++.