Why can't I declare templated type aliases inside of functions?

Question

Why can't I declare a templated type alias inside of a function?

#include <vector>

int main(){

    //type alias deceleration:
    template <typename T>
    using type = std::vector<T>;

    //type instantiation:
    type<int> t;

}

error: a template declaration cannot appear at block scope

Why are we forced to put these declarations outside of block scope?

#include <vector>

//type alias deceleration:
template <typename T>
using type = std::vector<T>;

int main(){

    //type instantiation:
    type<int> t;
}

Answer 1

The standard says so.

From the C++11 Standard (emphasis mine):

14 Template

2 A template-declaration can appear only as a namespace scope or class scope declaration. In a function template declaration, the last component of the declarator-id shall not be a template-id. [ Note: That last component may be an identifier, an operator-function-id, a conversion-function-id, or a literal-operator-id. In a class template declaration, if the class name is a simple-template-id, the declaration declares a class template partial specialization (14.5.5). —end note ]