Question

template <typename T>
class Test {
        friend Test<T> & operator * (T lhs, const Test<T> & rhs) {
            Test<T> r(rhs);
//              return r *= lhs;
        }
}

4 IntelliSense: identifier "T" is undefined

Why is T defined on line 3 but not line 4? I mean I guess it s not a real error just an intellisense error... It works anyway but is there something wrong? Can I fix it? Or remove the red squiggles somehow?

I am using visual studio 2010. I wonder if this happens in other versions as well?

Answer 1

Intellisense shows T as undefined because it is a generic template type. Depending on how you instantiate the class, T will be a different type. For example if you have Test<int> A, T is of type int, but if you call Test<string> A, T is of type string for that class and it s methods.

Answer 2

It seems to be getting confused by having the definition inside the class. So changing your code to:

template <typename T>
class Test {

    friend Test<T> & operator * (T lhs, const Test<T> & rhs);
};

template <typename T>
Test<T> & operator * (T lhs, const Test<T> & rhs) {
    Test<T> r(rhs);
}

makes the problem go away.

This appears to be a bug in the compiler your code should be legal based on my reading of the spec (specifically 11.4/5).

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