Extending the lifetime of scope objects

[Ali Çehreli]

What are all the cases that extend the lifetime of scoped objects?

Binding a delegate to a scope object extends the lifetime of that 
object, which would normally end upon exiting that scope. The lifetime 
of i is extended here:

int delegate(int) make_delegate()
{
     int i;    // lives as long as the returned delegate lives

     return (int param) {
         return i + param;         // uses i
     };
}

void main()
{
     auto del = make_delegate();
     del(42);                      // uses i
}

I was surprised to discover that, the same does not apply to struct 
objects, *if* the struct has a destructor:

struct S
{
     int i;

     ~this()  // prevents life extension
     {}
}

int delegate(int) make_delegate()
{
     auto s = S();

     return (int param) {
         return s.i + param;
     };
}

void main()
{
     auto del = make_delegate();
     del(42);
}

Error: variable deneme.make_delegate.s has scoped destruction, cannot 
build closure

Are the "life extending" cases short and simple? What are they? :)

Thank you,
Ali