merge-recursive: improve handling for rename/rename(2to1) conflicts

This makes the rename/rename(2to1) conflicts use the new
handle_file_collision() function.  Since that function was based
originally on the rename/rename(2to1) handling code, the main
differences here are in what was added.  In particular:

  * Instead of storing files at collide_path~HEAD and collide_path~MERGE,
    the files are two-way merged and recorded at collide_path.

  * Instead of recording the version of the renamed file that existed
    on the renamed side in the index (thus ignoring any changes that
    were made to the file on the side of history without the rename),
    we do a three-way content merge on the renamed path, then store
    that at either stage 2 or stage 3.

  * Note that since the content merge for each rename may have conflicts,
    and then we have to merge the two renamed files, we can end up with
    nested conflict markers.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 14 deletions

diff --git a/t/t6042-merge-rename-corner-cases.sh b/t/t6042-merge-rename-corner-cases.sh
index 3e934ae89e..b93139f628 100755
--- a/t/t6042-merge-rename-corner-cases.sh
+++ b/t/t6042-merge-rename-corner-cases.sh
@@ -464,17 +464,28 @@ test_expect_success 'handle rename/rename (2to1) conflict correctly' '
 		git ls-files -u c >out &&
 		test_line_count = 2 out &&
 		git ls-files -o >out &&
-		test_line_count = 3 out &&
+		test_line_count = 1 out &&
 
 		test_path_is_missing a &&
 		test_path_is_missing b &&
-		test_path_is_file c~HEAD &&
-		test_path_is_file c~C^0 &&
 
-		git rev-parse >expect   \
-			C:a     B:b     &&
-		git hash-object >actual \
-			c~HEAD  c~C^0   &&
+		git rev-parse >expect  \
+			C:a     B:b    &&
+		git rev-parse >actual  \
+			:2:c    :3:c   &&
+		test_cmp expect actual &&
+
+		# Test that the two-way merge in new_a is as expected
+		git cat-file -p :2:c >>ours &&
+		git cat-file -p :3:c >>theirs &&
+		>empty &&
+		test_must_fail git merge-file \
+			-L "HEAD" \
+			-L "" \
+			-L "C^0" \
+			ours empty theirs &&
+		git hash-object c >actual &&
+		git hash-object ours >expect &&
 		test_cmp expect actual
 	)
 '
@@ -940,7 +951,6 @@ test_expect_failure 'mod6-check: chains of rename/rename(1to2) and rename/rename
 test_conflicts_with_adds_and_renames() {
 	sideL=$1
 	sideR=$2
-	expect=$3
 
 	# Setup:
 	#          L
@@ -1048,7 +1058,7 @@ test_conflicts_with_adds_and_renames() {
 		)
 	'
 
-	test_expect_$expect "check simple $sideL/$sideR conflict" '
+	test_expect_success "check simple $sideL/$sideR conflict" '
 		(
 			cd simple_${sideL}_${sideR} &&
 
@@ -1094,10 +1104,10 @@ test_conflicts_with_adds_and_renames() {
 	'
 }
 
-test_conflicts_with_adds_and_renames rename rename failure
-test_conflicts_with_adds_and_renames rename add    success
-test_conflicts_with_adds_and_renames add    rename success
-test_conflicts_with_adds_and_renames add    add    success
+test_conflicts_with_adds_and_renames rename rename
+test_conflicts_with_adds_and_renames rename add
+test_conflicts_with_adds_and_renames add    rename
+test_conflicts_with_adds_and_renames add    add
 
 # Setup:
 #          L
@@ -1168,7 +1178,7 @@ test_expect_success 'setup nested conflicts from rename/rename(2to1)' '
 	)
 '
 
-test_expect_failure 'check nested conflicts from rename/rename(2to1)' '
+test_expect_success 'check nested conflicts from rename/rename(2to1)' '
 	(
 		cd nested_conflicts_from_rename_rename &&