merge-recursive: make "CONFLICT (rename/delete)" message show both paths

The current message printed by "git merge-recursive" for a rename/delete
conflict is like this:

CONFLICT (rename/delete): new-path deleted in HEAD and renamed in
other-branch. Version other-branch of new-path left in tree.

To be more helpful, the message should show both paths of the rename and
state that the deletion occurred at the old path, not the new path.  So
change the message to the following format:

CONFLICT (rename/delete): old-path deleted in HEAD and renamed to
new-path in other-branch. Version other-branch of new-path left in tree.

Since this doubles the number of cases in handle_change_delete (modify vs.
rename), refactor the code to halve the number of cases again by merging the
cases where o->branch1 has the change and o->branch2 has the delete with the
cases that are the other way around.

Also add a simple test of the new conflict message.

Signed-off-by: Matt McCutchen <matt@mattmccutchen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 63 insertions, 54 deletions

diff --git a/merge-recursive.c b/merge-recursive.c
index 23d6992f4..e55c2e174 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1061,16 +1061,20 @@ static int merge_file_one(struct merge_options *o,
 }
 
 static int handle_change_delete(struct merge_options *o,
-				 const char *path,
+				 const char *path, const char *old_path,
 				 const struct object_id *o_oid, int o_mode,
-				 const struct object_id *a_oid, int a_mode,
-				 const struct object_id *b_oid, int b_mode,
+				 const struct object_id *changed_oid,
+				 int changed_mode,
+				 const char *change_branch,
+				 const char *delete_branch,
 				 const char *change, const char *change_past)
 {
-	char *renamed = NULL;
+	char *alt_path = NULL;
+	const char *update_path = path;
 	int ret = 0;
+
 	if (dir_in_way(path, !o->call_depth, 0)) {
-		renamed = unique_path(o, path, a_oid ? o->branch1 : o->branch2);
+		update_path = alt_path = unique_path(o, path, change_branch);
 	}
 
 	if (o->call_depth) {
@@ -1081,43 +1085,43 @@ static int handle_change_delete(struct merge_options *o,
 		 */
 		ret = remove_file_from_cache(path);
 		if (!ret)
-			ret = update_file(o, 0, o_oid, o_mode,
-					  renamed ? renamed : path);
-	} else if (!a_oid) {
-		if (!renamed) {
-			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
-			       "and %s in %s. Version %s of %s left in tree."),
-			       change, path, o->branch1, change_past,
-			       o->branch2, o->branch2, path);
-			ret = update_file(o, 0, b_oid, b_mode, path);
-		} else {
-			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
-			       "and %s in %s. Version %s of %s left in tree at %s."),
-			       change, path, o->branch1, change_past,
-			       o->branch2, o->branch2, path, renamed);
-			ret = update_file(o, 0, b_oid, b_mode, renamed);
-		}
+			ret = update_file(o, 0, o_oid, o_mode, update_path);
 	} else {
-		if (!renamed) {
-			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
-			       "and %s in %s. Version %s of %s left in tree."),
-			       change, path, o->branch2, change_past,
-			       o->branch1, o->branch1, path);
+		if (!alt_path) {
+			if (!old_path) {
+				output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
+				       "and %s in %s. Version %s of %s left in tree."),
+				       change, path, delete_branch, change_past,
+				       change_branch, change_branch, path);
+			} else {
+				output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
+				       "and %s to %s in %s. Version %s of %s left in tree."),
+				       change, old_path, delete_branch, change_past, path,
+				       change_branch, change_branch, path);
+			}
 		} else {
-			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
-			       "and %s in %s. Version %s of %s left in tree at %s."),
-			       change, path, o->branch2, change_past,
-			       o->branch1, o->branch1, path, renamed);
-			ret = update_file(o, 0, a_oid, a_mode, renamed);
+			if (!old_path) {
+				output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
+				       "and %s in %s. Version %s of %s left in tree at %s."),
+				       change, path, delete_branch, change_past,
+				       change_branch, change_branch, path, alt_path);
+			} else {
+				output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
+				       "and %s to %s in %s. Version %s of %s left in tree at %s."),
+				       change, old_path, delete_branch, change_past, path,
+				       change_branch, change_branch, path, alt_path);
+			}
 		}
 		/*
-		 * No need to call update_file() on path when !renamed, since
-		 * that would needlessly touch path.  We could call
-		 * update_file_flags() with update_cache=0 and update_wd=0,
-		 * but that's a no-op.
+		 * No need to call update_file() on path when change_branch ==
+		 * o->branch1 && !alt_path, since that would needlessly touch
+		 * path.  We could call update_file_flags() with update_cache=0
+		 * and update_wd=0, but that's a no-op.
 		 */
+		if (change_branch != o->branch1 || alt_path)
+			ret = update_file(o, 0, changed_oid, changed_mode, update_path);
 	}
-	free(renamed);
+	free(alt_path);
 
 	return ret;
 }
@@ -1125,28 +1129,17 @@ static int handle_change_delete(struct merge_options *o,
 static int conflict_rename_delete(struct merge_options *o,
 				   struct diff_filepair *pair,
 				   const char *rename_branch,
-				   const char *other_branch)
+				   const char *delete_branch)
 {
 	const struct diff_filespec *orig = pair->one;
 	const struct diff_filespec *dest = pair->two;
-	const struct object_id *a_oid = NULL;
-	const struct object_id *b_oid = NULL;
-	int a_mode = 0;
-	int b_mode = 0;
-
-	if (rename_branch == o->branch1) {
-		a_oid = &dest->oid;
-		a_mode = dest->mode;
-	} else {
-		b_oid = &dest->oid;
-		b_mode = dest->mode;
-	}
 
 	if (handle_change_delete(o,
 				 o->call_depth ? orig->path : dest->path,
+				 o->call_depth ? NULL : orig->path,
 				 &orig->oid, orig->mode,
-				 a_oid, a_mode,
-				 b_oid, b_mode,
+				 &dest->oid, dest->mode,
+				 rename_branch, delete_branch,
 				 _("rename"), _("renamed")))
 		return -1;
 
@@ -1665,11 +1658,27 @@ static int handle_modify_delete(struct merge_options *o,
 				 struct object_id *a_oid, int a_mode,
 				 struct object_id *b_oid, int b_mode)
 {
+	const char *modify_branch, *delete_branch;
+	struct object_id *changed_oid;
+	int changed_mode;
+
+	if (a_oid) {
+		modify_branch = o->branch1;
+		delete_branch = o->branch2;
+		changed_oid = a_oid;
+		changed_mode = a_mode;
+	} else {
+		modify_branch = o->branch2;
+		delete_branch = o->branch1;
+		changed_oid = b_oid;
+		changed_mode = b_mode;
+	}
+
 	return handle_change_delete(o,
-				    path,
+				    path, NULL,
 				    o_oid, o_mode,
-				    a_oid, a_mode,
-				    b_oid, b_mode,
+				    changed_oid, changed_mode,
+				    modify_branch, delete_branch,
 				    _("modify"), _("modified"));
 }