How is this code invalid?

[thebluepandabear]

I am reading the fantastic book about D by Ali Çehreli, and he 
gives the following example when he talks about variadic 
functions:

```D
int[] numbersForLaterUse;

void foo(int[] numbers...) {
    numbersForLaterUse = numbers;
}

struct S {
   string[] namesForLaterUse;

   void foo(string[] names...) {
      namesForLaterUse = names;
   }
}
```

He says that the code above is a bug because:

"Both the free-standing function foo() and the member function 
S.foo() are in
error because they store slices to automatically-generated 
temporary arrays that
live on the program stack. Those arrays are valid only during the 
execution of the
variadic functions."

The thing is, when I run the code I get absolutely no error, so 
how is this exactly a 'bug' if the code runs properly? That's 
what I am confused about. What is the D compiler doing behind the 
scenes?