Create alias of same name in inner scope, bug or feature?

[Tejas via Digitalmars-d-learn]

```d
import std;
auto abc(T)(auto ref T a, auto ref T b){
    return a+b;
}
auto def(T)(auto ref T a, auto ref T b){
        return a*b;

}
alias macro_1 = abc;
void main()
{
    writeln(macro_1(15, 20));
    alias macro_1 = def;// is this NOT considered variable 
shadowing?
    writeln(macro_1(100, 20));

}
```