Re: BUG: mergetool fails on gitignore:d files

[Jeff King <peff@peff.net>]

On Sat, May 30, 2009 at 05:30:52PM +0200, Erik Sandberg wrote:

> If a version-controlled file is ignored by git, and a conflict arises
> on the file, and I use mergetool to resolve the conflict, then
> mergetool fails with a message like:
> 
> The following paths are ignored by one of your .gitignore files:
> a
> Use -f if you really want to add them.
> 
> The problem disappears if I edit the git-mergetool script to always
> pass -f to "git add", but I'm not sure if that's the right fix; I have
> a vague feeling that "git-update-index --add" could be more correct.

Actually, I think the problem is not in mergetool at all, but with the
dir.c code underlying "git add". "git add" really should not be
complaining, because you are not adding a new path at all, but are
rather adding content to a tracked path.

So this should work (and does):

  $ echo file >.gitignore
  $ echo content >file
  $ git add -f file ;# need -f because we are adding new path
  $ echo more content >>file
  $ git add file ;# don't need -f; it is not actually an "other" file

This is handled under the hood by the COLLECT_IGNORED option to
read_directory. When that code finds an ignored file, it checks the
index to make sure it is not actually a tracked file. However, the test
it uses does not take into account unmerged entries, and considers them
to still be ignored. "git ls-files" uses a more elaborate test and gets
the right answer. So I think we want to use the same test:

---
diff --git a/dir.c b/dir.c
index 0e6b752..bbfcb56 100644
--- a/dir.c
+++ b/dir.c
@@ -396,7 +396,7 @@ static struct dir_entry *dir_add_name(struct dir_struct *dir, const char *pathna
 
 static struct dir_entry *dir_add_ignored(struct dir_struct *dir, const char *pathname, int len)
 {
-	if (cache_name_pos(pathname, len) >= 0)
+	if (!cache_name_is_other(pathname, len))
 		return NULL;
 
 	ALLOC_GROW(dir->ignored, dir->ignored_nr+1, dir->ignored_alloc);