Taking the address of an rvalue struct

[dsimcha]

The following code uses the this reference in a struct member function to take
the address of an rvalue struct.  Is it well-defined behavior equivalent to
taking the address of a named stack-allocated struct, or is the compiler free
to break it in optimized mode?

struct SomeStruct {
    int num;

    this(int x) {
       num = x;
    }

    SomeStruct* addressOf() @property {
        return &this;
    }
}

void main() {
   auto ptr = SomeStruct(42).addressOf;
   writeln(ptr.num);
}