Re: git-add fails after file type change

A Large Angry SCM [off-list ref] writes:

Steven Grimm wrote:

quoted

In the course of experimenting with using git for my snapshot
backups, I ran into what looks like a bug in git-add: it croaks when
it tries to add a file whose type has changed, specifically when a
directory gets moved and a symbolic link is put in the old location
pointing to the new one. Here's a simple test case:

$ git init-db
defaulting to local storage area
$ mkdir dir
$ echo foo > dir/file
$ git add .
$ git commit -m "initial commit" -a
Committing initial tree f4bc9c50d08b041f5e096fa68e243c34170f1cd8
create mode 100644 dir/file
$ mv dir dir.real
$ ln -s dir.real dir
$ git add .
fatal: unable to add dir to index

Is "git add ." the wrong thing to do here? I have been using it as a
generic "pick up all the files I haven't added yet" command. Or is
this a bug?

For what it's worth, "git update-index dir" and "git update-index
--add dir" both fail too.

Did you try "git-update-index --replace dir"?

Good point.  I've forgotten about "--replace" codepath, although
that is all my code (May 7, 2005).

Maybe "git add" should internally use ADD_CACHE_OK_TO_REPLACE
(or error out and have an option to enable it)?

In any case, the error message could be made a bit more helpful,
like this.

---

diff --git a/read-cache.c b/read-cache.c
index eae4745..a602010 100644
--- a/read-cache.c
+++ b/read-cache.c

@@ -609,7 +609,7 @@ int add_cache_entry(struct cache_entry *ce, int option)
 	if (!skip_df_check &&
 	    check_file_directory_conflict(ce, pos, ok_to_replace)) {
 		if (!ok_to_replace)
-			return -1;
+			return error("'%s' appears as both a file and as a directory", ce->name);
 		pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
 		pos = -pos-1;
 	}