[PATCH] replace: forbid replacing an object with one of a different type

[Christian Couder <chriscool@tuxfamily.org>]

Users replacing an object with one of a different type were not
prevented to do so, even if it was obvious, and stated in the doc,
that bad things would result from doing that.

To avoid mistakes, it is better to just forbid that though.

The doc will be updated in a later patch.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
If this patch is considered useful, I will update the doc and
maybe add tests.

 builtin/replace.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/builtin/replace.c b/builtin/replace.c
index 59d3115..0246ab3 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -85,6 +85,7 @@ static int replace_object(const char *object_ref, const char *replace_ref,
 			  int force)
 {
 	unsigned char object[20], prev[20], repl[20];
+	enum object_type obj_type, repl_type;
 	char ref[PATH_MAX];
 	struct ref_lock *lock;
 
@@ -100,6 +101,14 @@ static int replace_object(const char *object_ref, const char *replace_ref,
 	if (check_refname_format(ref, 0))
 		die("'%s' is not a valid ref name.", ref);
 
+	obj_type = sha1_object_info(object, NULL);
+	repl_type = sha1_object_info(repl, NULL);
+	if (obj_type != repl_type)
+		die("Object ref '%s' is of type '%s'\n"
+		    "while replace ref '%s' is of type '%s'.",
+		    object_ref, typename(obj_type),
+		    replace_ref, typename(repl_type));
+
 	if (read_ref(ref, prev))
 		hashclr(prev);
 	else if (!force)
-- 
1.8.4.rc1.22.g132b1a0