//! Which OS mechanism a [`ProcessGroup`](crate::ProcessGroup) is using to
//! contain its child processes.
/// The containment mechanism actually in effect for a process group.
///
/// Surfaced so callers can tell *how* the no-orphan guarantee is enforced — in
/// particular when Linux silently falls back from a cgroup to a POSIX process
/// group (e.g. on a CI runner without cgroup delegation), which weakens the
/// guarantee against children that call `setsid`.