From: Jeff King <peff@peff.net>
Date: Thu, 12 Mar 2009 17:14:20 GMT
Subject: Re: git checkout -b origin/mybranch origin/mybranch
Message-ID: <20090312171420.GA2192@coredump.intra.peff.net>
In-Reply-To: <43d8ce650903120958n18baf6c0w9d083976b52d6e40@mail.gmail.com>

On Thu, Mar 12, 2009 at 04:58:22PM +0000, John Tapsell wrote:

> > -       if (resolve_ref(ref.buf, sha1, 1, NULL)) {
> > +       if (dwim_ref(name, strlen(name), sha1, &junk)) {
> > +               free(junk);
> 
> Presumably 'junk' is the resolved name?  I wonder if it's worth
> putting this info in the error message?

Hey, I said it was sloppy, right? ;)

Here's your suggestion, plus specifying which situation (existing branch
or ambiguous ref) would occur. It would still need tests. But I'm
curious to hear more opinions on this direction before cleaning it up
much more (at the very least, it needs some tests).

--- a/branch.c
+++ b/branch.c
@@ -133,6 +133,7 @@ void create_branch(const char *head,
 	unsigned char sha1[20];
 	char *real_ref, msg[PATH_MAX + 20];
 	struct strbuf ref = STRBUF_INIT;
+	char *existing;
 	int forcing = 0;
 	int len;
 
@@ -146,12 +147,18 @@ void create_branch(const char *head,
 	if (check_ref_format(ref.buf))
 		die("'%s' is not a valid branch name.", name);
 
-	if (resolve_ref(ref.buf, sha1, 1, NULL)) {
-		if (!force)
-			die("A branch named '%s' already exists.", name);
+	if (dwim_ref(name, strlen(name), sha1, &existing)) {
+		if (!force) {
+			if (!prefixcmp(existing, "refs/heads/"))
+				die("A branch named '%s' already exists.",
+				    name);
+			die("Creating '%s' would be ambiguous with"
+			    " the existing %s", name, existing);
+		}
 		else if (!is_bare_repository() && !strcmp(head, name))
 			die("Cannot force update the current branch.");
 		forcing = 1;
+		free(existing);
 	}
 
 	real_ref = NULL;