From: Junio C Hamano Date: Tue, 14 Apr 2015 08:05:10 GMT Subject: Re: git fsck: unreachable vs. dangling Message-ID: In-Reply-To: On Tue, Apr 14, 2015 at 12:16 AM, Sebastian Schuberth wrote: > Hi, > > reading through the fsck docs [1] I'm having a hard time understanding > what the difference between "unreachable" and "dangling" objects are. > > By example, suppose I have a commit A that is the tip of exactly one > branch (and no tag or other ref points to A). If I delete that branch, > is A now dangling, or unreachable, or both? Suppose that branch consists of two commits, A and A^. When you lose that branch (git branch -D that-branch), both A and A^ become unreachable. So are trees and blobs that appear only in A and A^ and nowhere else; they are also unreachable. A dangling object is an unreachable object that cannot be made reachable by any way other than pointing at it directly with a ref. A^ is not dangling, because you can make it reachable by pointing A (the tip of the original branch you just lost) with a ref. A on the other hand is dangling (if you had a tag object that points at A that you lost, then A is merely unreachable but not dangling, because you can point at that tag with a ref and make A reachable).