log: diagnose empty HEAD more clearly

diff --git a/revision.c b/revision.c
index 7ddbaa083e9e59d3db270b96b47a20e6c99bdaa3..734494abe6af2288e2f0bf6ad31eb5b74db9ea9c 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -2170,6 +2170,21 @@ static int handle_revision_pseudo_opt(const char *submodule,
        return 1;
 }
 
+static void NORETURN diagnose_missing_default(const char *def)
+{
+       unsigned char sha1[20];
+       int flags;
+       const char *refname;
+
+       refname = resolve_ref_unsafe(def, 0, sha1, &flags);
+       if (!refname || !(flags & REF_ISSYMREF) || (flags & REF_ISBROKEN))
+               die(_("your current branch appears to be broken"));
+
+       skip_prefix(refname, "refs/heads/", &refname);
+       die(_("your current branch '%s' does not have any commits yet"),
+           refname);
+}
+
 /*
  * Parse revision information, filling in the "rev_info" structure,
  * and removing the used arguments from the argument list.
@@ -2299,7 +2314,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
                struct object *object;
                struct object_context oc;
                if (get_sha1_with_context(revs->def, 0, sha1, &oc))
-                       die("bad default revision '%s'", revs->def);
+                       diagnose_missing_default(revs->def);
                object = get_reference(revs, revs->def, sha1, 0);
                add_pending_object_with_mode(revs, object, revs->def, oc.mode);
        }