push: fail early with detached HEAD and current

Setting push.default to current adds the refspec "HEAD" for the
transport layer to handle.  If "HEAD" doesn't resolve to a branch (and
since no refspec rhs is specified), the push fails after some time with
a cryptic error message:

$ git push
error: unable to push to unqualified destination: HEAD
The destination refspec neither matches an existing ref on the remote nor
begins with refs/, and we are unable to guess a prefix based on the source ref.
error: failed to push some refs to 'git@github.com:artagnon/git'

Fail early with a nicer error message:

$ git push
fatal: You are not currently on a branch.
To push the history leading to the current (detached HEAD)
state now, use

git push ram HEAD:<name-of-remote-branch>

Just like in the upstream and simple cases.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/push.c b/builtin/push.c
index ef3aa970ce0eaa87b771382368dbdcf49cff7e1d..ba2bd56ebc6a35b04b7c1f30b9446572dff0f5cf 100644 (file)
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -175,6 +175,8 @@ static void warn_unspecified_push_default_configuration(void)
 
 static void setup_default_push_refspecs(struct remote *remote)
 {
+       struct branch *branch;
+
        switch (push_default) {
        default:
        case PUSH_DEFAULT_UNSPECIFIED:
@@ -194,6 +196,9 @@ static void setup_default_push_refspecs(struct remote *remote)
                break;
 
        case PUSH_DEFAULT_CURRENT:
+               branch = branch_get(NULL);
+               if (!branch)
+                       die(_(message_detached_head_die), remote->name);
                add_refspec("HEAD");
                break;