Merge branch 'en/merge-recursive'

* en/merge-recursive: (41 commits)
  t6022: Use -eq not = to test output of wc -l
  merge-recursive:make_room_for_directories - work around dumb compilers
  merge-recursive: Remove redundant path clearing for D/F conflicts
  merge-recursive: Make room for directories in D/F conflicts
  handle_delete_modify(): Check whether D/F conflicts are still present
  merge_content(): Check whether D/F conflicts are still present
  conflict_rename_rename_1to2(): Fix checks for presence of D/F conflicts
  conflict_rename_delete(): Check whether D/F conflicts are still present
  merge-recursive: Delay modify/delete conflicts if D/F conflict present
  merge-recursive: Delay content merging for renames
  merge-recursive: Delay handling of rename/delete conflicts
  merge-recursive: Move handling of double rename of one file to other file
  merge-recursive: Move handling of double rename of one file to two
  merge-recursive: Avoid doubly merging rename/add conflict contents
  merge-recursive: Update merge_content() call signature
  merge-recursive: Update conflict_rename_rename_1to2() call signature
  merge-recursive: Structure process_df_entry() to handle more cases
  merge-recursive: Have process_entry() skip D/F or rename entries
  merge-recursive: New function to assist resolving renames in-core only
  merge-recursive: New data structures for deferring of D/F conflicts
  ...

Conflicts:
	t/t6020-merge-df.sh
	t/t6036-recursive-corner-cases.sh

1 files changed, 182 insertions, 3 deletions

diff --git a/t/t6036-recursive-corner-cases.sh b/t/t6036-recursive-corner-cases.sh
index 004c365..871577d 100755
--- a/t/t6036-recursive-corner-cases.sh
+++ b/t/t6036-recursive-corner-cases.sh
@@ -14,7 +14,7 @@ test_description='recursive merge corner cases'
 #  R1  R2
 #
 
-test_expect_success setup '
+test_expect_success 'setup basic criss-cross + rename with no modifications' '
 	ten="0 1 2 3 4 5 6 7 8 9" &&
 	for i in $ten
 	do
@@ -45,11 +45,190 @@ test_expect_success setup '
 	git tag R2
 '
 
-test_expect_success merge '
+test_expect_success 'merge simple rename+criss-cross with no modifications' '
 	git reset --hard &&
 	git checkout L2^0 &&
 
-	test_must_fail git merge -s recursive R2^0
+	test_must_fail git merge -s recursive R2^0 &&
+
+	test 5 = $(git ls-files -s | wc -l) &&
+	test 3 = $(git ls-files -u | wc -l) &&
+	test 0 = $(git ls-files -o | wc -l) &&
+
+	test $(git rev-parse :0:one) = $(git rev-parse L2:one) &&
+	test $(git rev-parse :0:two) = $(git rev-parse R2:two) &&
+	test $(git rev-parse :2:three) = $(git rev-parse L2:three) &&
+	test $(git rev-parse :3:three) = $(git rev-parse R2:three) &&
+
+	cp two merged &&
+	>empty &&
+	test_must_fail git merge-file \
+		-L "Temporary merge branch 2" \
+		-L "" \
+		-L "Temporary merge branch 1" \
+		merged empty one &&
+	test $(git rev-parse :1:three) = $(git hash-object merged)
+'
+
+#
+# Same as before, but modify L1 slightly:
+#
+#  L1m L2
+#   o---o
+#  / \ / \
+# o   X   ?
+#  \ / \ /
+#   o---o
+#  R1  R2
+#
+
+test_expect_success 'setup criss-cross + rename merges with basic modification' '
+	git rm -rf . &&
+	git clean -fdqx &&
+	rm -rf .git &&
+	git init &&
+
+	ten="0 1 2 3 4 5 6 7 8 9"
+	for i in $ten
+	do
+		echo line $i in a sample file
+	done >one &&
+	for i in $ten
+	do
+		echo line $i in another sample file
+	done >two &&
+	git add one two &&
+	test_tick && git commit -m initial &&
+
+	git branch L1 &&
+	git checkout -b R1 &&
+	git mv one three &&
+	echo more >>two &&
+	git add two &&
+	test_tick && git commit -m R1 &&
+
+	git checkout L1 &&
+	git mv two three &&
+	test_tick && git commit -m L1 &&
+
+	git checkout L1^0 &&
+	test_tick && git merge -s ours R1 &&
+	git tag L2 &&
+
+	git checkout R1^0 &&
+	test_tick && git merge -s ours L1 &&
+	git tag R2
+'
+
+test_expect_success 'merge criss-cross + rename merges with basic modification' '
+	git reset --hard &&
+	git checkout L2^0 &&
+
+	test_must_fail git merge -s recursive R2^0 &&
+
+	test 5 = $(git ls-files -s | wc -l) &&
+	test 3 = $(git ls-files -u | wc -l) &&
+	test 0 = $(git ls-files -o | wc -l) &&
+
+	test $(git rev-parse :0:one) = $(git rev-parse L2:one) &&
+	test $(git rev-parse :0:two) = $(git rev-parse R2:two) &&
+	test $(git rev-parse :2:three) = $(git rev-parse L2:three) &&
+	test $(git rev-parse :3:three) = $(git rev-parse R2:three) &&
+
+	head -n 10 two >merged &&
+	cp one merge-me &&
+	>empty &&
+	test_must_fail git merge-file \
+		-L "Temporary merge branch 2" \
+		-L "" \
+		-L "Temporary merge branch 1" \
+		merged empty merge-me &&
+	test $(git rev-parse :1:three) = $(git hash-object merged)
+'
+
+#
+# For the next test, we start with three commits in two lines of development
+# which setup a rename/add conflict:
+#   Commit A: File 'a' exists
+#   Commit B: Rename 'a' -> 'new_a'
+#   Commit C: Modify 'a', create different 'new_a'
+# Later, two different people merge and resolve differently:
+#   Commit D: Merge B & C, ignoring separately created 'new_a'
+#   Commit E: Merge B & C making use of some piece of secondary 'new_a'
+# Finally, someone goes to merge D & E.  Does git detect the conflict?
+#
+#      B   D
+#      o---o
+#     / \ / \
+#  A o   X   ? F
+#     \ / \ /
+#      o---o
+#      C   E
+#
+
+test_expect_success 'setup differently handled merges of rename/add conflict' '
+	git rm -rf . &&
+	git clean -fdqx &&
+	rm -rf .git &&
+	git init &&
+
+	printf "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n" >a &&
+	git add a &&
+	test_tick && git commit -m A &&
+
+	git branch B &&
+	git checkout -b C &&
+	echo 10 >>a &&
+	echo "other content" >>new_a &&
+	git add a new_a &&
+	test_tick && git commit -m C &&
+
+	git checkout B &&
+	git mv a new_a &&
+	test_tick && git commit -m B &&
+
+	git checkout B^0 &&
+	test_must_fail git merge C &&
+	git clean -f &&
+	test_tick && git commit -m D &&
+	git tag D &&
+
+	git checkout C^0 &&
+	test_must_fail git merge B &&
+	rm new_a~HEAD new_a &&
+	printf "Incorrectly merged content" >>new_a &&
+	git add -u &&
+	test_tick && git commit -m E &&
+	git tag E
+'
+
+test_expect_success 'git detects differently handled merges conflict' '
+	git reset --hard &&
+	git checkout D^0 &&
+
+	git merge -s recursive E^0 && {
+		echo "BAD: should have conflicted"
+		test "Incorrectly merged content" = "$(cat new_a)" &&
+			echo "BAD: Silently accepted wrong content"
+		return 1
+	}
+
+	test 3 = $(git ls-files -s | wc -l) &&
+	test 3 = $(git ls-files -u | wc -l) &&
+	test 0 = $(git ls-files -o | wc -l) &&
+
+	test $(git rev-parse :2:new_a) = $(git rev-parse D:new_a) &&
+	test $(git rev-parse :3:new_a) = $(git rev-parse E:new_a) &&
+
+	git cat-file -p B:new_a >>merged &&
+	git cat-file -p C:new_a >>merge-me &&
+	>empty &&
+	test_must_fail git merge-file \
+		-L "Temporary merge branch 2" \
+		-L "" \
+		-L "Temporary merge branch 1" \
+		merged empty merge-me &&
+	test $(git rev-parse :1:new_a) = $(git hash-object merged)
 '
 
 test_done