Makefile: help people who run 'make check' by mistake

diff --git a/builtin-checkout.c b/builtin-checkout.c
index c4fc2b2c562725018789dead3b86ccfbc4e2925f..05eee4ecc71d7a20d9faf59c849d3c693ae4cc8d 100644 (file)
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -32,7 +32,7 @@ static int post_checkout_hook(struct commit *old, struct commit *new,
 
        memset(&proc, 0, sizeof(proc));
        argv[0] = name;
-       argv[1] = xstrdup(sha1_to_hex(old->object.sha1));
+       argv[1] = xstrdup(sha1_to_hex(old ? old->object.sha1 : null_sha1));
        argv[2] = xstrdup(sha1_to_hex(new->object.sha1));
        argv[3] = changed ? "1" : "0";
        argv[4] = NULL;
@@ -360,10 +360,10 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 
        strbuf_init(&msg, 0);
        old_desc = old->name;
-       if (!old_desc)
+       if (!old_desc && old->commit)
                old_desc = sha1_to_hex(old->commit->object.sha1);
        strbuf_addf(&msg, "checkout: moving from %s to %s",
-                   old_desc, new->name);
+                   old_desc ? old_desc : "(invalid)", new->name);
 
        if (new->path) {
                create_symref("HEAD", new->path, msg.buf);
@@ -419,7 +419,7 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
         * a new commit, we want to mention the old commit once more
         * to remind the user that it might be lost.
         */
-       if (!opts->quiet && !old.path && new->commit != old.commit)
+       if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
                describe_detached_head("Previous HEAD position was", old.commit);
 
        if (!old.commit) {
@@ -565,6 +565,18 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
                return checkout_paths(source_tree, pathspec);
        }
 
+       if (opts.new_branch) {
+               struct strbuf buf;
+               strbuf_init(&buf, 0);
+               strbuf_addstr(&buf, "refs/heads/");
+               strbuf_addstr(&buf, opts.new_branch);
+               if (!get_sha1(buf.buf, rev))
+                       die("git checkout: branch %s already exists", opts.new_branch);
+               if (check_ref_format(buf.buf))
+                       die("git checkout: we do not like '%s' as a branch name.", opts.new_branch);
+               strbuf_release(&buf);
+       }
+
        if (new.name && !new.commit) {
                die("Cannot switch branch to a non-commit.");
        }