[PATCH 0/6] push.default in the triangular world

@@ -48,7 +48,6 @@ test_expect_success '"upstream" pushes to configured upstream' '
 test_expect_success '"upstream" does not push on unconfigured remote' '
 	git checkout master &&
 	test_unconfig branch.master.remote &&
-	test_config push.default upstream &&
 	test_commit three &&
 	test_push_failure upstream
 '

@@ -57,7 +56,6 @@ test_expect_success '"upstream" does not push on unconfigured branch' '
 	git checkout master &&
 	test_config branch.master.remote parent1 &&
 	test_unconfig branch.master.merge &&
-	test_config push.default upstream
 	test_commit four &&
 	test_push_failure upstream
 '

@@ -1826,39 +1826,43 @@ pull.twohead::
 	The default merge strategy to use when pulling a single branch.
 
 push.default::
-	Defines the action `git push` should take if no refspec is given
-	on the command line, no refspec is configured in the remote, and
-	no refspec is implied by any of the options given on the command
-	line. Possible values are:
+	Defines the action `git push` should take if no refspec is
+	explicitly given.  Different values are well-suited for
+	specific workflows; for instance, in a purely central workflow
+	(i.e. the fetch source is equal to the push destination),
+	`upstream` is probably what you want.  Possible values are:
 +
 --
-* `nothing` - do not push anything.
-* `matching` - push all branches having the same name in both ends.
-  This is for those who prepare all the branches into a publishable
-  shape and then push them out with a single command.  It is not
-  appropriate for pushing into a repository shared by multiple users,
-  since locally stalled branches will attempt a non-fast forward push
-  if other users updated the branch.
-  +
-  This is currently the default, but Git 2.0 will change the default
-  to `simple`.
-* `upstream` - push the current branch to its upstream branch
-  (`tracking` is a deprecated synonym for this).
-  With this, `git push` will update the same remote ref as the one which
-  is merged by `git pull`, making `push` and `pull` symmetrical.
-  See "branch.<name>.merge" for how to configure the upstream branch.
+* `nothing` - do not push anything (error out) unless a refspec is
+  explicitly given.  Very safe, but not very convenient.
+
+* `current` - push the current branch to update a branch with the same
+  name on the receiving end.  Works in both central and non-central
+  workflows.  Equivalent to pushing the refspec "$branch" ($branch is
+  the name of the current branch).
+
+* `upstream` - push the current branch to a branch with the name
+  branch.$branch.merge on the receiving end, and error out if the push
+  destination is not the same as branch.$branch.remote.  The name
+  "upstream" refers to "@{u[pstream]}" in linkgit:gitrevisions[7],
+  which makes sense only if both branch.$branch.remote and
+  branch.$branch.merge are set.  It makes sure that a `push` is
+  symmetrical to `pull` in central workflows, and cannot be used in
+  non-central workflows.
+
 * `simple` - like `upstream`, but refuses to push if the upstream
   branch's name is different from the local one. This is the safest
   option and is well-suited for beginners. It will become the default
   in Git 2.0.
-* `current` - push the current branch to a branch of the same name.
+
+* `matching` - push all branches having the same name on both ends
+  (essentially ignoring all newly created local branches).
+  Well-suited for those who want to batch-update a specific set of
+  branches they consistently work on.  Use with caution, especially
+  when pushing with '--force'.  Equivalent to pushing the refspec ":".
+  This is currently the default, but Git 2.0 will change the default
+  to `simple`.
 --
-+
-The `simple`, `current` and `upstream` modes are for those who want to
-push out a single branch after finishing work, even when the other
-branches are not yet ready to be pushed out. If you are working with
-other people to push into the same shared repository, you would want
-to use one of these.
 
 rebase.stat::
 	Whether to show a diffstat of what changed upstream since the last

@@ -1850,10 +1850,12 @@ push.default::
   symmetrical to `pull` in central workflows, and cannot be used in
   non-central workflows.
 
-* `simple` - like `upstream`, but refuses to push if the upstream
-  branch's name is different from the local one. This is the safest
-  option and is well-suited for beginners. It will become the default
-  in Git 2.0.
+* `simple` - a safer version of `current`; push the current branch to
+  update a branch with the same name on the receiving end, with a
+  safety feature: in central workflows, error out if
+  branch.$branch.merge is set and not equal to $branch, to make sure
+  that a `push` and `push` are never asymmetrical.  It will become the
+  default in Git 2.0.
 
 * `matching` - push all branches having the same name on both ends
   (essentially ignoring all newly created local branches).

@@ -120,6 +120,25 @@ static const char message_detached_head_die[] =
 	   "\n"
 	   "    git push %s HEAD:<name-of-remote-branch>\n");
 
+static void setup_push_simple(struct remote *remote)
+{
+	struct branch *branch = branch_get(NULL);
+	if (!branch)
+		die(_(message_detached_head_die), remote->name);
+	if (!branch->merge_nr || !branch->merge || !branch->remote_name)
+		/* No upstream configured */
+		goto end;
+	if (branch->merge_nr != 1)
+		die(_("The current branch %s has multiple upstream branches, "
+		    "refusing to push."), branch->name);
+	if (!strcmp(branch->remote_name, remote->name) &&
+		strcmp(branch->refname, branch->merge[0]->src))
+		/* Central workflow safety feature */
+		die_push_simple(branch, remote);
+end:
+	add_refspec(branch->name);
+}
+
 static void setup_push_upstream(struct remote *remote, int simple)
 {
 	struct strbuf refspec = STRBUF_INIT;

@@ -188,7 +207,7 @@ static void setup_default_push_refspecs(struct remote *remote)
 		break;
 
 	case PUSH_DEFAULT_SIMPLE:
-		setup_push_upstream(remote, 1);
+		setup_push_simple(remote);
 		break;
 
 	case PUSH_DEFAULT_UPSTREAM:

@@ -85,7 +85,7 @@ test_expect_success 'push from/to new branch with current creates remote branch'
 test_expect_success 'push to existing branch, with no upstream configured' '
 	test_config branch.master.remote repo1 &&
 	git checkout master &&
-	test_push_failure simple &&
+	test_push_success simple master &&
 	test_push_failure upstream
 '
 

@@ -139,7 +139,7 @@ end:
 	add_refspec(branch->name);
 }
 
-static void setup_push_upstream(struct remote *remote, int simple)
+static void setup_push_upstream(struct remote *remote)
 {
 	struct strbuf refspec = STRBUF_INIT;
 	struct branch *branch = branch_get(NULL);

@@ -161,8 +161,6 @@ static void setup_push_upstream(struct remote *remote, int simple)
 		      "your current branch '%s', without telling me what to push\n"
 		      "to update which remote branch."),
 		    remote->name, branch->name);
-	if (simple && strcmp(branch->refname, branch->merge[0]->src))
-		die_push_simple(branch, remote);
 
 	strbuf_addf(&refspec, "%s:%s", branch->name, branch->merge[0]->src);
 	add_refspec(refspec.buf);

@@ -211,7 +209,7 @@ static void setup_default_push_refspecs(struct remote *remote)
 		break;
 
 	case PUSH_DEFAULT_UPSTREAM:
-		setup_push_upstream(remote, 0);
+		setup_push_upstream(remote);
 		break;
 
 	case PUSH_DEFAULT_CURRENT:

@@ -15,17 +15,19 @@ test_expect_success 'setup bare remotes' '
 
 # $1 = local revision
 # $2 = remote revision (tested to be equal to the local one)
+# $3 = [optional] repo to check for actual output (repo1 by default)
 check_pushed_commit () {
 	git log -1 --format='%h %s' "$1" >expect &&
-	git --git-dir=repo1 log -1 --format='%h %s' "$2" >actual &&
+	git --git-dir="${3:-repo1}" log -1 --format='%h %s' "$2" >actual &&
 	test_cmp expect actual
 }
 
 # $1 = push.default value
 # $2 = expected target branch for the push
+# $3 = [optional] repo to check for actual output (repo1 by default)
 test_push_success () {
 	git -c push.default="$1" push &&
-	check_pushed_commit HEAD "$2"
+	check_pushed_commit HEAD "$2" "$3"
 }
 
 # $1 = push.default value

@@ -39,6 +39,26 @@ test_push_failure () {
 	test_cmp expect actual
 }
 
+# $1 = success or failure
+# $2 = push.default value
+# $3 = branch to check for actual output (master or foo)
+# $4 = [optional] switch to triangular workflow
+test_pushdefault_workflow () {
+	workflow=central
+	pushdefault=parent1
+	if test -n "${4-}"; then
+		workflow=triangular
+		pushdefault=parent2
+	fi
+test_expect_success "push.default = $2 $1 in $workflow workflows" "
+	test_config branch.master.remote parent1 &&
+	test_config branch.master.merge refs/heads/foo &&
+	test_config remote.pushdefault $pushdefault &&
+	test_commit commit-for-$2${4+-triangular} &&
+	test_push_$1 $2 $3 ${4+repo2}
+"
+}
+
 test_expect_success '"upstream" pushes to configured upstream' '
 	git checkout master &&
 	test_config branch.master.remote parent1 &&

@@ -115,4 +135,20 @@ test_expect_success 'push to existing branch, upstream configured with different
 	test_cmp expect-other-name actual-other-name
 '
 
+## test_pushdefault_workflow() arguments:
+# $1 = success or failure
+# $2 = push.default value
+# $3 = branch to check for actual output (master or foo)
+# $4 = [optional] switch to triangular workflow
+
+test_pushdefault_workflow success current master  # breaks push/pull symmetry
+test_pushdefault_workflow success upstream foo    # preserves push/pull symmetry
+test_pushdefault_workflow failure simple master   # errors out on asymmetry
+test_pushdefault_workflow success matching master # always works
+
+test_pushdefault_workflow success current master triangular  # always works
+test_pushdefault_workflow failure upstream foo triangular    # always errors out
+test_pushdefault_workflow success simple master triangular   # works like current
+test_pushdefault_workflow success matching master triangular # always works
+
 test_done