Re: [PATCH v2] pull: merge into unborn by fast-forwarding from empty tree

From: Thomas Rast <trast@inf.ethz.ch>
Date: Jun 20, 2013, 13:33 UTC
Message-ID: <87mwqk6h5d.fsf@linux-k42r.v.cablecom.net>
In-Reply-To: <87zjuk6hr2.fsf@linux-k42r.v.cablecom.net>

Thomas Rast <trast@inf.ethz.ch> writes:

Show 24 quoted lines

> Jeff King <peff@peff.net> writes:
>
>> On Thu, Jun 20, 2013 at 03:06:01PM +0200, Thomas Rast wrote:
>>
>>> +test_expect_success 'pulling into void does not overwrite staged files' '
>>> +	git init cloned-staged-colliding &&
>>> +	(
>>> +		cd cloned-staged-colliding &&
>>> +		echo "alternate content" >file &&
>>> +		git add file &&
>>> +		test_must_fail git pull .. master &&
>>> +		echo "alternate content" >expect &&
>>> +		test_cmp expect file &&
>>> +		git cat-file blob :file >file.index &&
>>> +		test_cmp expect file.index
>>> +	)
>>> +'
>>
>> I naively would have expected this to leave us in a conflicted state
>> over "file".  But I guess read-tree just rejects it, because we are not
>> doing a real three-way merge.  I'm not sure it is that big a deal; this
>> is more about safety than about creating a conflicted/resolvable state.
>
> Note that the test_must_fail essentially tests that the merge is rejected.

Bah, no it doesn't, a conflicting merge also returns a nonzero status. Sigh.

If you meant we should actually conflict, I'm not sure what options there would be other than actually calling a merge driver. And we could actually do this like so (it'll obviously break the tests):

diff --git i/git-pull.sh w/git-pull.sh
index 1f84383..b3d36a8 100755
--- i/git-pull.sh
+++ w/git-pull.sh
@@ -276,7 +276,7 @@ then
 	# lose index/worktree changes that the user already made on
 	# the unborn branch.
 	empty_tree=4b825dc642cb6eb9a060e54bf8d69288fbee4904
-	git read-tree -m -u $empty_tree HEAD || exit 1
+	git merge-recursive $empty_tree -- $(git write-tree) HEAD || exit 1
 	exit
 fi

-- 
Thomas Rast
trast@{inf,student}.ethz.ch