Mutable statics have the same restrictions as normal statics, except that the
type of the value is not required to ascribe to `Sync`.
-#### `'static` lifetime elision
+#### `'static` lifetime elision [unstable]
Both constant and static declarations of reference types have *implicit*
`'static` lifetimes unless an explicit lifetime is specified. As such, the
lifetimes. Returning to our previous example:
```rust
+#[feature(static_in_const)]
const BIT1: u32 = 1 << 0;
const BIT2: u32 = 1 << 1;