Re: can I always ignore a file during a merge?

From: Jeff King <peff@peff.net>
Date: Jul 3, 2012, 07:38 UTC
Message-ID: <20120703073847.GD16679@sigill.intra.peff.net>
In-Reply-To: <p06240817cc114629c20f@[192.168.1.122]>

On Wed, Jun 27, 2012 at 07:39:03PM -0400, Stephen Bannasch wrote:

> Is there a way to merge from branchA to branchB and from branchB to
> branchA while completely ignoring changes to a file that is tracked
> and exists in both branches?

No. Fundamentally, a commit object in git consists of a content state (i.e., a pointer to a tree object) and a pointer to all previous history (i.e., zero or more "parent" pointers to commit objects). The semantics of a commit object can be thought of as "I have looked at all of the history in all of the parent commits, and the state contained in my tree pointer supersedes them all".

So you could make merge B into A, but keep A's copy of the file (e.g., using the "ours" strategy). But that is saying that you considered the state of both A and B, and decided that A's version supersedes what happened in B. If you later wanted to merge from A to B, B's version of the file would not even be considered as an outcome for the merge.

There isn't really a clever way to work around this via a different merge strategy; it's a fundamental aspect of git's data structure for storing history.

-Peff