need examples to understand postfix expression grammar

[FabArd]

Thank you for your examples.

I did some tests based on your examples and I found that you can 
also assign a type to an auto variable:
```d
void main(){
    auto x = double();
    x = 2;
    static assert(is(typeof(x) == double));
    assert(x == 2);
}
```
Another example with a qualified identifier:
```d
class Test {
     enum nb : int {
         one = 1
     }
}
void main(){
    auto d = Test.nb();
    static assert(is(typeof(d) == Test.nb));
}
```
It seems that the grammar rule could be written more precisely:

PostfixExpression:
- PostfixExpression ( ArgumentListopt )
- TypeCtors<opt> BasicType ( AssignExpressionopt )

Indeed the type conversion takes only one or no argument but 
never a list.