Template type arguments (C++ only)

You cannot use one of the following as a template argument for a type template parameter:

• a local type
• a type with no linkage
• an unnamed type
• a type compounded from any of the above types

If it is ambiguous whether a template argument is a type or an expression, the template argument is considered to be a type. The following example demonstrates this:

template<class T> void f() { };
template<int i> void f() { };

int main() {
  f<int()>();
}

The function call f<int()>() calls the function with T as a template argument – the compiler considers int() as a type – and therefore implicitly instantiates and calls the first f().

Related information

• Block/local scope
• No linkage
• Bit field members
• typedef definitions