v2, 3 partsEarly HEAD resolution in push.default = current

The commit message in [3/3] is rewritten although I've mentioned the original motivation at the end.

No other changes.

Ramkumar Ramachandra (3):
  push: factor out the detached HEAD error message
  push: fail early with detached HEAD and current
  push: make push.default = current resolve HEAD early

 builtin/push.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

With push.default set to upstream or simple, and a detached HEAD, git push prints the following error:

  $ 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>

This error is not unique to upstream or simple: current cannot push with a detached HEAD either. So, factor out the error string in preparation for using it in current.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/push.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

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>
---
 builtin/push.c | 4 ++++
 1 file changed, 4 insertions(+)

Ramkumar Ramachandra <artagnon@gmail.com> writes:

This means well, but I am not sure calling branch_get() for all other cases that do not care about the current branch is a right thing to do. It's not like you need branch variable to free some resource after done, or pass it around to callees from this function.

Would it hurt to do

	if (!branch_get(NULL))
		die(...);

here, without the first hunk?  

Junio C Hamano wrote:

And how would I change the add_refspec() call to take branch->name in [3/3]?

Ramkumar Ramachandra <artagnon@gmail.com> writes:

By doing something like this, perhaps?

	struct ... branch;

        switch (...) {
        ...
        case it-only-matters-here:
        	branch = branch_get(NULL);
                if (!branch)
			die(...);
	}

Here: put this at the end of the series and autosquash.

-- 8< --
From: Ramkumar Ramachandra <artagnon@gmail.com>
Date: Thu, 30 May 2013 01:29:59 +0530
Subject: [PATCH] fixup! HEAD~2

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/push.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

With this change, the output of the push (with push.default set to current) changes subtly from:

  $ git push
  ...
   * [new branch]      HEAD -> push-current-head

to:

  $ git push
  ...
   * [new branch]      push-current-head -> push-current-head

This patch was written with a different motivation. There is a problem unique to push.default = current:

  # on branch push-current-head
  $ git push
  # on another terminal
  $ git checkout master
  # return to the first terminal
  # the push tried to push master!

This happens because the 'git checkout' on the second terminal races with the 'git push' on the first terminal. Although this patch does not solve the core problem (there is still no guarantee that 'git push' on the first terminal will resolve HEAD before 'git checkout' changes HEAD on the second), it works in practice.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/push.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)