Exchange the stop states referred to by lhs and rhs.
Set lhs to refer to the stop state (or lack thereof) that rhs referred to before the call, and vice versa. Implementation note: this function is required by the standard to be a hidden friend ([hidden.friends], [stopsource.general]).
| Name | Description |
|---|---|
| lhs | first source participating in the swap |
| rhs | second source participating in the swap |