Enum BranchClass 

pub enum BranchClass {
    Equal,
    Behind,
    Ahead,
    Diverged,
    RemoteOnly,
    NoRemote,
}

Classification of a local branch relative to its origin counterpart.

Direction note: merge-base --is-ancestor A B returns 0 iff A is reachable from B.

• local == remote → Equal
• local ancestor-of remote (not equal) → Behind (FF possible: remote has new commits)
• remote ancestor-of local (not equal) → Ahead (local has unpushed commits)
• neither is an ancestor of the other → Diverged (manual resolution required)
• local ref absent, remote ref present → RemoteOnly (safe to create local ref)
• remote ref cannot be resolved → NoRemote (local-only or no origin)

Variants

Equal

Behind

Ahead

Diverged

RemoteOnly

Local ref does not exist; origin ref does. Safe to create the local ref.

NoRemote

Remote ref cannot be resolved. Branch is local-only or origin is unreachable.