This seems fishy, it's a mutable static but you're setting it as constant!

You may want to test fancier cases as well, you want to make sure that nothing is recursively constant as well. Something like:

```rust
struct Foo { a: int };
static mut A: &'static mut [Foo] = &'static mut [Foo { a : 3 }];

fn main() {
    A[0].a += 3;
}
```