Merge branch 'jk/at-push-sha1'

Introduce <branch>@{push} short-hand to denote the remote-tracking
branch that tracks the branch at the remote the <branch> would be
pushed to.

* jk/at-push-sha1:
  for-each-ref: accept "%(push)" format
  for-each-ref: use skip_prefix instead of starts_with
  sha1_name: implement @{push} shorthand
  sha1_name: refactor interpret_upstream_mark
  sha1_name: refactor upstream_mark
  remote.c: add branch_get_push
  remote.c: return upstream name from stat_tracking_info
  remote.c: untangle error logic in branch_get_upstream
  remote.c: report specific errors from branch_get_upstream
  remote.c: introduce branch_get_upstream helper
  remote.c: hoist read_config into remote_get_1
  remote.c: provide per-branch pushremote name
  remote.c: hoist branch.*.remote lookup out of remote_get_1
  remote.c: drop "remote" pointer from "struct branch"
  remote.c: refactor setup of branch->merge list
  remote.c: drop default_remote_name variable

Documentation/git-for-each-ref.txt

@@ -97,6 +97,12 @@ upstream::
 	or "=" (in sync).  Has no effect if the ref does not have
 	tracking information associated with it.
 
+push::
+	The name of a local ref which represents the `@{push}` location
+	for the displayed ref. Respects `:short`, `:track`, and
+	`:trackshort` options as `upstream` does. Produces an empty
+	string if no `@{push}` ref is configured.
+
 HEAD::
 	'*' if HEAD matches current ref (the checked out branch), ' '
 	otherwise.

Documentation/revisions.txt

@@ -98,6 +98,31 @@ some output processing may assume ref names in UTF-8.
   `branch.<name>.merge`).  A missing branchname defaults to the
   current one.
 
+'<branchname>@\{push\}', e.g. 'master@\{push\}', '@\{push\}'::
+  The suffix '@\{push}' reports the branch "where we would push to" if
+  `git push` were run while `branchname` was checked out (or the current
+  'HEAD' if no branchname is specified). Since our push destination is
+  in a remote repository, of course, we report the local tracking branch
+  that corresponds to that branch (i.e., something in 'refs/remotes/').
++
+Here's an example to make it more clear:
++
+------------------------------
+$ git config push.default current
+$ git config remote.pushdefault myfork
+$ git checkout -b mybranch origin/master
+
+$ git rev-parse --symbolic-full-name @{upstream}
+refs/remotes/origin/master
+
+$ git rev-parse --symbolic-full-name @{push}
+refs/remotes/myfork/mybranch
+------------------------------
++
+Note in the example that we set up a triangular workflow, where we pull
+from one location and push to another. In a non-triangular workflow,
+'@\{push}' is the same as '@\{upstream}', and there is no need for it.
+
 '<rev>{caret}', e.g. 'HEAD{caret}, v1.5.1{caret}0'::
   A suffix '{caret}' to a revision parameter means the first parent of
   that commit object.  '{caret}<n>' means the <n>th parent (i.e.

Documentation/technical/api-remote.txt

@@ -97,10 +97,6 @@ It contains:
 
 	The name of the remote listed in the configuration.
 
-`remote`::
-
-	The struct remote for that remote.
-
 `merge_name`::
 
 	An array of the "merge" lines in the configuration.

builtin/branch.c

@@ -123,14 +123,12 @@ static int branch_merged(int kind, const char *name,
 
 	if (kind == REF_LOCAL_BRANCH) {
 		struct branch *branch = branch_get(name);
+		const char *upstream = branch_get_upstream(branch, NULL);
 		unsigned char sha1[20];
 
-		if (branch &&
-		    branch->merge &&
-		    branch->merge[0] &&
-		    branch->merge[0]->dst &&
+		if (upstream &&
 		    (reference_name = reference_name_to_free =
-		     resolve_refdup(branch->merge[0]->dst, RESOLVE_REF_READING,
+		     resolve_refdup(upstream, RESOLVE_REF_READING,
 				    sha1, NULL)) != NULL)
 			reference_rev = lookup_commit_reference(sha1);
 	}
@@ -427,25 +425,19 @@ static void fill_tracking_info(struct strbuf *stat, const char *branch_name,
 	int ours, theirs;
 	char *ref = NULL;
 	struct branch *branch = branch_get(branch_name);
+	const char *upstream;
 	struct strbuf fancy = STRBUF_INIT;
 	int upstream_is_gone = 0;
 	int added_decoration = 1;
 
-	switch (stat_tracking_info(branch, &ours, &theirs)) {
-	case 0:
-		/* no base */
-		return;
-	case -1:
-		/* with "gone" base */
+	if (stat_tracking_info(branch, &ours, &theirs, &upstream) < 0) {
+		if (!upstream)
+			return;
 		upstream_is_gone = 1;
-		break;
-	default:
-		/* with base */
-		break;
 	}
 
 	if (show_upstream_ref) {
-		ref = shorten_unambiguous_ref(branch->merge[0]->dst, 0);
+		ref = shorten_unambiguous_ref(upstream, 0);
 		if (want_color(branch_use_color))
 			strbuf_addf(&fancy, "%s%s%s",
 					branch_get_color(BRANCH_COLOR_UPSTREAM),

builtin/for-each-ref.c

@@ -74,6 +74,7 @@ static struct {
 	{ "contents:body" },
 	{ "contents:signature" },
 	{ "upstream" },
+	{ "push" },
 	{ "symref" },
 	{ "flag" },
 	{ "HEAD" },
@@ -659,15 +660,26 @@ static void populate_value(struct refinfo *ref)
 		else if (starts_with(name, "symref"))
 			refname = ref->symref ? ref->symref : "";
 		else if (starts_with(name, "upstream")) {
+			const char *branch_name;
 			/* only local branches may have an upstream */
-			if (!starts_with(ref->refname, "refs/heads/"))
+			if (!skip_prefix(ref->refname, "refs/heads/",
+					 &branch_name))
 				continue;
-			branch = branch_get(ref->refname + 11);
+			branch = branch_get(branch_name);
 
-			if (!branch || !branch->merge || !branch->merge[0] ||
-			    !branch->merge[0]->dst)
+			refname = branch_get_upstream(branch, NULL);
+			if (!refname)
+				continue;
+		} else if (starts_with(name, "push")) {
+			const char *branch_name;
+			if (!skip_prefix(ref->refname, "refs/heads/",
+					 &branch_name))
+				continue;
+			branch = branch_get(branch_name);
+
+			refname = branch_get_push(branch, NULL);
+			if (!refname)
 				continue;
-			refname = branch->merge[0]->dst;
 		} else if (starts_with(name, "color:")) {
 			char color[COLOR_MAXLEN] = "";
 
@@ -713,11 +725,12 @@ static void populate_value(struct refinfo *ref)
 				refname = shorten_unambiguous_ref(refname,
 						      warn_ambiguous_refs);
 			else if (!strcmp(formatp, "track") &&
-				 starts_with(name, "upstream")) {
+				 (starts_with(name, "upstream") ||
+				  starts_with(name, "push"))) {
 				char buf[40];
 
 				if (stat_tracking_info(branch, &num_ours,
-						       &num_theirs) != 1)
+						       &num_theirs, NULL))
 					continue;
 
 				if (!num_ours && !num_theirs)
@@ -735,11 +748,12 @@ static void populate_value(struct refinfo *ref)
 				}
 				continue;
 			} else if (!strcmp(formatp, "trackshort") &&
-				   starts_with(name, "upstream")) {
+				   (starts_with(name, "upstream") ||
+				    starts_with(name, "push"))) {
 				assert(branch);
 
 				if (stat_tracking_info(branch, &num_ours,
-							&num_theirs) != 1)
+							&num_theirs, NULL))
 					continue;
 
 				if (!num_ours && !num_theirs)

builtin/log.c

@@ -1632,16 +1632,13 @@ int cmd_cherry(int argc, const char **argv, const char *prefix)
 		break;
 	default:
 		current_branch = branch_get(NULL);
-		if (!current_branch || !current_branch->merge
-					|| !current_branch->merge[0]
-					|| !current_branch->merge[0]->dst) {
+		upstream = branch_get_upstream(current_branch, NULL);
+		if (!upstream) {
 			fprintf(stderr, _("Could not find a tracked"
 					" remote branch, please"
 					" specify <upstream> manually.\n"));
 			usage_with_options(cherry_usage, options);
 		}
-
-		upstream = current_branch->merge[0]->dst;
 	}
 
 	init_revisions(&revs, prefix);

builtin/merge.c

@@ -933,7 +933,7 @@ static int setup_with_upstream(const char ***argv)
 
 	if (!branch)
 		die(_("No current branch."));
-	if (!branch->remote)
+	if (!branch->remote_name)
 		die(_("No remote for the current branch."));
 	if (!branch->merge_nr)
 		die(_("No default upstream defined for the current branch."));