Merge branch 'en/d-f-conflict-fix'

* en/d-f-conflict-fix:
  merge-recursive: Avoid excessive output for and reprocessing of renames
  merge-recursive: Fix multiple file rename across D/F conflict
  t6031: Add a testcase covering multiple renames across a D/F conflict
  merge-recursive: Fix typo
  Mark tests that use symlinks as needing SYMLINKS prerequisite
  t/t6035-merge-dir-to-symlink.sh: Remove TODO on passing test
  fast-import: Improve robustness when D->F changes provided in wrong order
  fast-export: Fix output order of D/F changes
  merge_recursive: Fix renames across paths below D/F conflicts
  merge-recursive: Fix D/F conflicts
  Add a rename + D/F conflict testcase
  Add additional testcases for D/F conflicts

Conflicts:
	merge-recursive.c

8 files changed, 276 insertions, 24 deletions

diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 66cafe6330..a9bbf8653d 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -148,10 +148,39 @@ static void handle_object(const unsigned char *sha1)
 	free(buf);
 }
 
+static int depth_first(const void *a_, const void *b_)
+{
+	const struct diff_filepair *a = *((const struct diff_filepair **)a_);
+	const struct diff_filepair *b = *((const struct diff_filepair **)b_);
+	const char *name_a, *name_b;
+	int len_a, len_b, len;
+	int cmp;
+
+	name_a = a->one ? a->one->path : a->two->path;
+	name_b = b->one ? b->one->path : b->two->path;
+
+	len_a = strlen(name_a);
+	len_b = strlen(name_b);
+	len = (len_a < len_b) ? len_a : len_b;
+
+	/* strcmp will sort 'd' before 'd/e', we want 'd/e' before 'd' */
+	cmp = memcmp(name_a, name_b, len);
+	if (cmp)
+		return cmp;
+	return (len_b - len_a);
+}
+
 static void show_filemodify(struct diff_queue_struct *q,
 			    struct diff_options *options, void *data)
 {
 	int i;
+
+	/*
+	 * Handle files below a directory first, in case they are all deleted
+	 * and the directory changes to a file or symlink.
+	 */
+	qsort(q->queue, q->nr, sizeof(q->queue[0]), depth_first);
+
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filespec *ospec = q->queue[i]->one;
 		struct diff_filespec *spec = q->queue[i]->two;
diff --git a/fast-import.c b/fast-import.c
index dd51ac48b6..2317b0fe75 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1528,6 +1528,14 @@ static int tree_content_remove(
 	for (i = 0; i < t->entry_count; i++) {
 		e = t->entries[i];
 		if (e->name->str_len == n && !strncmp(p, e->name->str_dat, n)) {
+			if (slash1 && !S_ISDIR(e->versions[1].mode))
+				/*
+				 * If p names a file in some subdirectory, and a
+				 * file or symlink matching the name of the
+				 * parent directory of p exists, then p cannot
+				 * exist and need not be deleted.
+				 */
+				return 1;
 			if (!slash1 || !S_ISDIR(e->versions[1].mode))
 				goto del_entry;
 			if (!e->tree)
diff --git a/merge-recursive.c b/merge-recursive.c
index 638076ec6e..df90be44a5 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1017,14 +1017,22 @@ static int process_renames(struct merge_options *o,
 
 				if (mfi.clean &&
 				    sha_eq(mfi.sha, ren1->pair->two->sha1) &&
-				    mfi.mode == ren1->pair->two->mode)
+				    mfi.mode == ren1->pair->two->mode) {
 					/*
-					 * This messaged is part of
+					 * This message is part of
 					 * t6022 test. If you change
 					 * it update the test too.
 					 */
 					output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
-				else {
+
+					/* There may be higher stage entries left
+					 * in the index (e.g. due to a D/F
+					 * conflict) that need to be resolved.
+					 */
+					if (!ren1->dst_entry->stages[2].mode !=
+					    !ren1->dst_entry->stages[3].mode)
+						ren1->dst_entry->processed = 0;
+				} else {
 					if (mfi.merge || !mfi.clean)
 						output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
 					if (mfi.merge)
@@ -1070,6 +1078,7 @@ static int process_entry(struct merge_options *o,
 	unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
 	unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
 
+	entry->processed = 1;
 	if (o_sha && (!a_sha || !b_sha)) {
 		/* Case A: Deleted in one */
 		if ((!a_sha && !b_sha) ||
@@ -1102,33 +1111,28 @@ static int process_entry(struct merge_options *o,
 	} else if ((!o_sha && a_sha && !b_sha) ||
 		   (!o_sha && !a_sha && b_sha)) {
 		/* Case B: Added in one. */
-		const char *add_branch;
-		const char *other_branch;
 		unsigned mode;
 		const unsigned char *sha;
-		const char *conf;
 
 		if (a_sha) {
-			add_branch = o->branch1;
-			other_branch = o->branch2;
 			mode = a_mode;
 			sha = a_sha;
-			conf = "file/directory";
 		} else {
-			add_branch = o->branch2;
-			other_branch = o->branch1;
 			mode = b_mode;
 			sha = b_sha;
-			conf = "directory/file";
 		}
 		if (string_list_has_string(&o->current_directory_set, path)) {
-			const char *new_path = unique_path(o, path, add_branch);
-			clean_merge = 0;
-			output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
-			       "Adding %s as %s",
-			       conf, path, other_branch, path, new_path);
-			remove_file(o, 0, path, 0);
-			update_file(o, 0, sha, mode, new_path);
+			/* Handle D->F conflicts after all subfiles */
+			entry->processed = 0;
+			/* But get any file out of the way now, so conflicted
+			 * entries below the directory of the same name can
+			 * be put in the working directory.
+			 */
+			if (a_sha)
+				output(o, 2, "Removing %s", path);
+			/* do not touch working file if it did not exist */
+			remove_file(o, 0, path, !a_sha);
+			return 1; /* Assume clean till processed */
 		} else {
 			output(o, 2, "Adding %s", path);
 			update_file(o, 1, sha, mode, path);
@@ -1176,6 +1180,64 @@ static int process_entry(struct merge_options *o,
 	return clean_merge;
 }
 
+/*
+ * Per entry merge function for D/F conflicts, to be called only after
+ * all files below dir have been processed.  We do this because in the
+ * cases we can cleanly resolve D/F conflicts, process_entry() can clean
+ * out all the files below the directory for us.
+ */
+static int process_df_entry(struct merge_options *o,
+			 const char *path, struct stage_data *entry)
+{
+	int clean_merge = 1;
+	unsigned o_mode = entry->stages[1].mode;
+	unsigned a_mode = entry->stages[2].mode;
+	unsigned b_mode = entry->stages[3].mode;
+	unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
+	unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
+	unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
+	const char *add_branch;
+	const char *other_branch;
+	unsigned mode;
+	const unsigned char *sha;
+	const char *conf;
+	struct stat st;
+
+	/* We currently only handle D->F cases */
+	assert((!o_sha && a_sha && !b_sha) ||
+	       (!o_sha && !a_sha && b_sha));
+
+	entry->processed = 1;
+
+	if (a_sha) {
+		add_branch = o->branch1;
+		other_branch = o->branch2;
+		mode = a_mode;
+		sha = a_sha;
+		conf = "file/directory";
+	} else {
+		add_branch = o->branch2;
+		other_branch = o->branch1;
+		mode = b_mode;
+		sha = b_sha;
+		conf = "directory/file";
+	}
+	if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
+		const char *new_path = unique_path(o, path, add_branch);
+		clean_merge = 0;
+		output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
+		       "Adding %s as %s",
+		       conf, path, other_branch, path, new_path);
+		remove_file(o, 0, path, 0);
+		update_file(o, 0, sha, mode, new_path);
+	} else {
+		output(o, 2, "Adding %s", path);
+		update_file(o, 1, sha, mode, path);
+	}
+
+	return clean_merge;
+}
+
 void set_porcelain_error_msgs(const char **msgs, const char *cmd)
 {
 	const char *msg;
@@ -1269,6 +1331,13 @@ int merge_trees(struct merge_options *o,
 				&& !process_entry(o, path, e))
 				clean = 0;
 		}
+		for (i = 0; i < entries->nr; i++) {
+			const char *path = entries->items[i].string;
+			struct stage_data *e = entries->items[i].util;
+			if (!e->processed
+				&& !process_df_entry(o, path, e))
+				clean = 0;
+		}
 
 		string_list_clear(re_merge, 0);
 		string_list_clear(re_head, 0);
diff --git a/t/t3509-cherry-pick-merge-df.sh b/t/t3509-cherry-pick-merge-df.sh
new file mode 100755
index 0000000000..a5ccdbf8fc
--- /dev/null
+++ b/t/t3509-cherry-pick-merge-df.sh
@@ -0,0 +1,35 @@
+#!/bin/sh
+
+test_description='Test cherry-pick with directory/file conflicts'
+. ./test-lib.sh
+
+test_expect_success SYMLINKS 'Setup rename across paths each below D/F conflicts' '
+	mkdir a &&
+	>a/f &&
+	git add a &&
+	git commit -m a &&
+
+	mkdir b &&
+	ln -s ../a b/a &&
+	git add b &&
+	git commit -m b &&
+
+	git checkout -b branch &&
+	rm b/a &&
+	mv a b/a &&
+	ln -s b/a a &&
+	git add . &&
+	git commit -m swap &&
+
+	>f1 &&
+	git add f1 &&
+	git commit -m f1
+'
+
+test_expect_success SYMLINKS 'Cherry-pick succeeds with rename across D/F conflicts' '
+	git reset --hard &&
+	git checkout master^0 &&
+	git cherry-pick branch
+'
+
+test_done
diff --git a/t/t6020-merge-df.sh b/t/t6020-merge-df.sh
index e71c687f2b..490d397114 100755
--- a/t/t6020-merge-df.sh
+++ b/t/t6020-merge-df.sh
@@ -22,7 +22,7 @@ git commit -m "File: dir"'
 
 test_expect_code 1 'Merge with d/f conflicts' 'git merge "merge msg" B master'
 
-test_expect_failure 'F/D conflict' '
+test_expect_success 'F/D conflict' '
 	git reset --hard &&
 	git checkout master &&
 	rm .git/index &&
diff --git a/t/t6031-merge-recursive.sh b/t/t6031-merge-recursive.sh
index 8a3304fb0b..bd75e0e643 100755
--- a/t/t6031-merge-recursive.sh
+++ b/t/t6031-merge-recursive.sh
@@ -57,4 +57,35 @@ test_expect_success FILEMODE 'verify executable bit on file' '
 	test -x file2
 '
 
+test_expect_success 'merging with triple rename across D/F conflict' '
+	git reset --hard HEAD &&
+	git checkout -b main &&
+	git rm -rf . &&
+
+	echo "just a file" >sub1 &&
+	mkdir -p sub2 &&
+	echo content1 >sub2/file1 &&
+	echo content2 >sub2/file2 &&
+	echo content3 >sub2/file3 &&
+	mkdir simple &&
+	echo base >simple/bar &&
+	git add -A &&
+	test_tick &&
+	git commit -m base &&
+
+	git checkout -b other &&
+	echo more >>simple/bar &&
+	test_tick &&
+	git commit -a -m changesimplefile &&
+
+	git checkout main &&
+	git rm sub1 &&
+	git mv sub2 sub1 &&
+	test_tick &&
+	git commit -m changefiletodir &&
+
+	test_tick &&
+	git merge other
+'
+
 test_done
diff --git a/t/t6035-merge-dir-to-symlink.sh b/t/t6035-merge-dir-to-symlink.sh
index cd3190c4a6..dc09513be5 100755
--- a/t/t6035-merge-dir-to-symlink.sh
+++ b/t/t6035-merge-dir-to-symlink.sh
@@ -48,7 +48,7 @@ test_expect_success 'setup for merge test' '
 	git tag baseline
 '
 
-test_expect_success 'do not lose a/b-2/c/d in merge (resolve)' '
+test_expect_success 'Handle D/F conflict, do not lose a/b-2/c/d in merge (resolve)' '
 	git reset --hard &&
 	git checkout baseline^0 &&
 	git merge -s resolve master &&
@@ -56,7 +56,7 @@ test_expect_success 'do not lose a/b-2/c/d in merge (resolve)' '
 	test -f a/b-2/c/d
 '
 
-test_expect_failure 'do not lose a/b-2/c/d in merge (recursive)' '
+test_expect_success 'Handle D/F conflict, do not lose a/b-2/c/d in merge (recursive)' '
 	git reset --hard &&
 	git checkout baseline^0 &&
 	git merge -s recursive master &&
@@ -64,6 +64,54 @@ test_expect_failure 'do not lose a/b-2/c/d in merge (recursive)' '
 	test -f a/b-2/c/d
 '
 
+test_expect_success 'Handle F/D conflict, do not lose a/b-2/c/d in merge (resolve)' '
+	git reset --hard &&
+	git checkout master^0 &&
+	git merge -s resolve baseline^0 &&
+	test -h a/b &&
+	test -f a/b-2/c/d
+'
+
+test_expect_success 'Handle F/D conflict, do not lose a/b-2/c/d in merge (recursive)' '
+	git reset --hard &&
+	git checkout master^0 &&
+	git merge -s recursive baseline^0 &&
+	test -h a/b &&
+	test -f a/b-2/c/d
+'
+
+test_expect_failure 'do not lose untracked in merge (resolve)' '
+	git reset --hard &&
+	git checkout baseline^0 &&
+	>a/b/c/e &&
+	test_must_fail git merge -s resolve master &&
+	test -f a/b/c/e &&
+	test -f a/b-2/c/d
+'
+
+test_expect_success 'do not lose untracked in merge (recursive)' '
+	git reset --hard &&
+	git checkout baseline^0 &&
+	>a/b/c/e &&
+	test_must_fail git merge -s recursive master &&
+	test -f a/b/c/e &&
+	test -f a/b-2/c/d
+'
+
+test_expect_success 'do not lose modifications in merge (resolve)' '
+	git reset --hard &&
+	git checkout baseline^0 &&
+	echo more content >>a/b/c/d &&
+	test_must_fail git merge -s resolve master
+'
+
+test_expect_success 'do not lose modifications in merge (recursive)' '
+	git reset --hard &&
+	git checkout baseline^0 &&
+	echo more content >>a/b/c/d &&
+	test_must_fail git merge -s recursive master
+'
+
 test_expect_success 'setup a merge where dir a/b-2 changed to symlink' '
 	git reset --hard &&
 	git checkout start^0 &&
@@ -74,7 +122,7 @@ test_expect_success 'setup a merge where dir a/b-2 changed to symlink' '
 	git tag test2
 '
 
-test_expect_success 'merge should not have conflicts (resolve)' '
+test_expect_success 'merge should not have D/F conflicts (resolve)' '
 	git reset --hard &&
 	git checkout baseline^0 &&
 	git merge -s resolve test2 &&
@@ -82,7 +130,7 @@ test_expect_success 'merge should not have conflicts (resolve)' '
 	test -f a/b/c/d
 '
 
-test_expect_failure 'merge should not have conflicts (recursive)' '
+test_expect_success 'merge should not have D/F conflicts (recursive)' '
 	git reset --hard &&
 	git checkout baseline^0 &&
 	git merge -s recursive test2 &&
@@ -90,4 +138,12 @@ test_expect_failure 'merge should not have conflicts (recursive)' '
 	test -f a/b/c/d
 '
 
+test_expect_success 'merge should not have F/D conflicts (recursive)' '
+	git reset --hard &&
+	git checkout -b foo test2 &&
+	git merge -s recursive baseline^0 &&
+	test -h a/b-2 &&
+	test -f a/b/c/d
+'
+
 test_done
diff --git a/t/t9350-fast-export.sh b/t/t9350-fast-export.sh
index d831404fba..8c8e679468 100755
--- a/t/t9350-fast-export.sh
+++ b/t/t9350-fast-export.sh
@@ -390,4 +390,28 @@ test_expect_success 'tree_tag-obj'    'git fast-export tree_tag-obj'
 test_expect_success 'tag-obj_tag'     'git fast-export tag-obj_tag'
 test_expect_success 'tag-obj_tag-obj' 'git fast-export tag-obj_tag-obj'
 
+test_expect_success SYMLINKS 'directory becomes symlink'        '
+	git init dirtosymlink &&
+	git init result &&
+	(
+		cd dirtosymlink &&
+		mkdir foo &&
+		mkdir bar &&
+		echo hello > foo/world &&
+		echo hello > bar/world &&
+		git add foo/world bar/world &&
+		git commit -q -mone &&
+		git rm -r foo &&
+		ln -s bar foo &&
+		git add foo &&
+		git commit -q -mtwo
+	) &&
+	(
+		cd dirtosymlink &&
+		git fast-export master -- foo |
+		(cd ../result && git fast-import --quiet)
+	) &&
+	(cd result && git show master:foo)
+'
+
 test_done