C2070 - 操作数大小非法

The following code looks fine to me:

    #include <stdio.h>

    template <typename T>
    struct A
    {
        static float m_kA[];
    };

    template <typename T>
    float A<T>::m_kA[] = {1.0f, 2.0f, 3.0f};

    int main()
    {
        printf("%d
", 
            sizeof(A<unsigned int>::m_kA) /
            sizeof(A<unsigned int>::m_kA[0]));
        return 0;
    }

但是当我用 VC9 编译时出现以下错误

error C2070: 'float []': illegal sizeof operand