Re: [PATCH] rerere: demonstrate a weakness with identical conflicts in different files

From

Johannes Sixt <j.sixt@viscovery.net>

Date

Aug 12, 2010, 07:28 UTC

Message-ID

<4C63A292.4010604@viscovery.net>

In-Reply-To

<7vfwykv92a.fsf@alter.siamese.dyndns.org>

Am 8/12/2010 4:50, schrieb Junio C Hamano:

> Yes, rr-cache/ database keys off of the
> conflict id, so if your repository has more than one contents that produce
> exactly the same conflict, say F and G, then, most likely:
> 
>  * You see one of them first, say F, record preimage.F and record its
>    resolution as postimage.F
> 
>  * You encounter conflict G; record it in thisimage, try three-way merge
>    between postimage.F and that using preimage.F as the common ancestor.
>    If this doesn't work (and it likely doesn't), rerere punts.

Squash in this and the test passes:

diff --git a/t/t4208-rerere-dup.sh b/t/t4208-rerere-dup.sh
index 34c182a..2afa0ef 100755
--- a/t/t4208-rerere-dup.sh
+++ b/t/t4208-rerere-dup.sh
@@ -12,6 +12,7 @@
 test_expect_success 'setup' '
 	cat > a1 <<- EOF &&
 	alpha
+	delta
 	beta
 	gamma
 	EOF
@@ -23,6 +24,7 @@ test_expect_success 'setup' '
 	git checkout -b first &&
 	cat > a1 <<- EOF &&
 	alpha
+	delta
 	BETA
 	gamma
 	EOF
@@ -32,6 +34,7 @@ test_expect_success 'setup' '
 	git checkout master &&
 	cat > a1 <<- EOF &&
 	alpha
+	delta
 	----
 	gamma
 	EOF
@@ -49,6 +52,7 @@ test_expect_success 'merge records
 test_expect_success 'record a resolution' '
 	cat > a1 <<- EOF &&
 	alpha
+	delta
 	--beta--
 	gamma
 	EOF
@@ -61,7 +65,7 @@ test_expect_success 'postimage must
 '

 test_expect_success 'same resolution recorded twice' '
-	test $(grep "Recorded resolution" actual | wc -l) = 2 &&
+#	test $(grep "Recorded resolution" actual | wc -l) = 2 &&
 	test $(ls .git/rr-cache | wc -w) = 1
 '


The last hunk is necessary because the output of rerere is now:

Recorded resolution for 'a1'.
Resolved 'a2' using previous resolution.

where the second statement is slightly misleading because the resolution
was not "used". But already present in the file (the resolution-merge
still succeeded, hence, rerere thought it had "used" the resolution).

I assumed that in my case I had identical text immediately outside the
conflict markers, and so I also assumed that the resolution-merge would
succeed, but it seems I was wrong. I'll go back and investigate closer as
time permits.

Thanks for your help so far.

-- Hannes