On Fri, Mar 01, 2013 at 08:57:03AM -0800, Junio C Hamano wrote: > An initial checkout is *supposed* to happen in an empty working > tree, so if we code it not to overwrite an existing path in the > working tree, the user cannot lose possibly precious contents with > an mistaken initial checkout (they will instead appear as modified > relative to the index), while in the normal case we will write out > the contents from the HEAD through the index. We could attempt "we > do not have to if the user behaves, but with this we could help > misbehaving users" if we used twoway merge for an initial checkout.
That matches my thinking. It is probably not worth touching, though, since it is not causing any problems. I just found it curious that the exact same (and only, as far as I can see) exception we make for initial_checkout is the same thing we have to tweak here. > Having said that, I notice that in the normal codepath (e.g. "git > clone" without the "--no-checkout" option) we no longer use twoway > merge for the initial checkout. Back when "git clone" was a > scripted Porcelain, I think we used to do a twoway read-tree. It > may be that we broke it when "clone" was rewritten in C, but the > breakage is to the "we do not have to..." thing, so it may not be a > big deal. The one-way merge that we use now in clone makes a lot of sense to me. We do not have a "previous state" we were based on. > The only case that matters in today's code is "git checkout" > (without any option or argument) immediately after "git clone -n", I > think. The special casing for this initial checkout in twoway merge > is needed because we go from HEAD to HEAD in that case, and we do > not want to keep the artificial local removals from the index; we > start from not even having the $GIT_INDEX_FILE, so without the > special case all paths appear to have been "rm --cached", which is > usually not what the user would want to see ;-) Right. I just wondered if such a checkout should instead be a "reset", in which case it would fall under the proposed patch. But "git checkout" never does a twoway_merge with o->reset; instead, it uses a one-way merge. Anyway, that is all tangential to the bug at hand. > > ... My worry would be that somebody is > > using "--reset" but expecting the removal to be carried through > > (technically, "--reset" is documented as "-m but discard unmerged > > entries", but we are not really treating it that way here). > > I've checked all in-tree uses of "read-tree --reset -u". > > Nobody seems to use that combination, either from scripts or from C > (i.e. when opts.update==1 and opts.merge==1, opts.reset is not set) > with a twoway merge, other than "git am --abort/--skip". I can believe it. So do we want to do that fix, then? Did you want to roll up the two halves of it with a test and write a commit message? I feel like you could write a much more coherent one than I could on this subject. -Peff -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html