add_cache_entry(): removal of file foo does not conflict with foo/bar

Similarly, removal of file foo/bar does not conflict with a file foo.

Signed-off-by: Junio C Hamano <junkio@cox.net>

read-cache.c

@@ -487,6 +487,8 @@ static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replac
 			continue;
 		if (p->name[len] != '/')
 			continue;
+		if (!ce_stage(p) && !p->ce_mode)
+			continue;
 		retval = -1;
 		if (!ok_to_replace)
 			break;
@@ -519,26 +521,37 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
 
 		pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
 		if (pos >= 0) {
-			retval = -1;
-			if (!ok_to_replace)
-				break;
-			remove_cache_entry_at(pos);
-			continue;
+			/*
+			 * Found one, but not so fast.  This could
+			 * be a marker that says "I was here, but
+			 * I am being removed".  Such an entry is
+			 * not a part of the resulting tree, and
+			 * it is Ok to have a directory at the same
+			 * path.
+			 */
+			if (stage || active_cache[pos]->ce_mode) {
+				retval = -1;
+				if (!ok_to_replace)
+					break;
+				remove_cache_entry_at(pos);
+				continue;
+			}
 		}
+		else
+			pos = -pos-1;
 
 		/*
 		 * Trivial optimization: if we find an entry that
 		 * already matches the sub-directory, then we know
 		 * we're ok, and we can exit.
 		 */
-		pos = -pos-1;
 		while (pos < active_nr) {
 			struct cache_entry *p = active_cache[pos];
 			if ((ce_namelen(p) <= len) ||
 			    (p->name[len] != '/') ||
 			    memcmp(p->name, name, len))
 				break; /* not our subdirectory */
-			if (ce_stage(p) == stage)
+			if (ce_stage(p) == stage && (stage || p->ce_mode))
 				/* p is at the same stage as our entry, and
 				 * is a subdirectory of what we are looking
 				 * at, so we cannot have conflicts at our
@@ -562,12 +575,21 @@ static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace
  */
 static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
 {
+	int retval;
+
+	/*
+	 * When ce is an "I am going away" entry, we allow it to be added
+	 */
+	if (!ce_stage(ce) && !ce->ce_mode)
+		return 0;
+
 	/*
 	 * We check if the path is a sub-path of a subsequent pathname
 	 * first, since removing those will not change the position
-	 * in the array
+	 * in the array.
 	 */
-	int retval = has_file_name(ce, pos, ok_to_replace);
+	retval = has_file_name(ce, pos, ok_to_replace);
+
 	/*
 	 * Then check if the path might have a clashing sub-directory
 	 * before it.