Using static_assert in Template Code

1template <typename T>
2T sum(T a, T b) {
3  static_assert(std::is_integral<T>::value ||
4                std::is_floating_point<T>::value,
5                "sum() requires numeric types");
6  return a + b;
7}

1template <typename T>
2class Derived : public T {
3  static_assert(std::is_base_of<Base, T>::value,
4                "T must be derived from Base");
5  // ...
6};

1template <typename T, typename U>
2void assert_same() {
3  static_assert(std::is_same<T, U>::value,
4                "Types must be the same");
5}

1template <typename T>
2void process(T t) {
3  static_assert(!std::is_pointer<T>::value,
4                "Pointers are not allowed");
5  static_assert(!std::is_reference<T>::value,
6                "References are not allowed");
7// ...
8}

1template <typename T, typename... Args>
2void construct(Args&&... args) {
3  static_assert(std::is_constructible<T, Args...>::value,
4                "T must be constructible from Args");
5  T obj(std::forward<Args>(args)...);
6// ...
7}

1template <typename T>
2void foo(T t) {
3  static_assert(std::is_integral_v<T>,
4                "foo() requires an integral type");
5  // ...
6}