remote.c: fix handling of %(push:remoteref)

Looking at the value of %(push:remoteref) only handles the case when an
explicit push refspec is passed. But it does not handle the fallback
cases of looking at the configuration value of `push.default`.

In particular, doing something like

    git config push.default current
    git for-each-ref --format='%(push)'
    git for-each-ref --format='%(push:remoteref)'

prints a useful tracking ref for the first for-each-ref, but an empty
string for the second.

Since the intention of %(push:remoteref), from 9700fae5ee (for-each-ref:
let upstream/push report the remote ref name) is to get exactly which
branch `git push` will push to, even in the fallback cases, fix this.

To get the meaning of %(push:remoteref), `ref-filter.c` calls
`remote_ref_for_branch`. We simply add a new static helper function,
`branch_get_push_remoteref` that follows the logic of
`branch_get_push_1`, and call it from `remote_ref_for_branch`.

We also update t/6300-for-each-ref.sh to handle all `push.default`
strategies. This involves testing `push.default=simple` twice, once
where there is a matching upstream branch and once when there is none.

Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote.c

@@ -516,28 +516,6 @@ const char *pushremote_for_branch(struct branch *branch, int *explicit)
 	return remote_for_branch(branch, explicit);
 }
 
-const char *remote_ref_for_branch(struct branch *branch, int for_push)
-{
-	if (branch) {
-		if (!for_push) {
-			if (branch->merge_nr) {
-				return branch->merge_name[0];
-			}
-		} else {
-			const char *dst, *remote_name =
-				pushremote_for_branch(branch, NULL);
-			struct remote *remote = remote_get(remote_name);
-
-			if (remote && remote->push.nr &&
-			    (dst = apply_refspecs(&remote->push,
-						  branch->refname))) {
-				return dst;
-			}
-		}
-	}
-	return NULL;
-}
-
 static struct remote *remote_get_1(const char *name,
 				   const char *(*get_default)(struct branch *, int *))
 {
@@ -1656,6 +1634,64 @@ static const char *tracking_for_push_dest(struct remote *remote,
 	return ret;
 }
 
+/**
+ * Return the local name of the remote tracking branch, as in
+ * %(push:remoteref), that corresponds to the ref we would push to given a
+ * bare `git push` while `branch` is checked out.
+ * See also branch_get_push_1 below.
+ */
+static const char *branch_get_push_remoteref(struct branch *branch)
+{
+	struct remote *remote;
+
+	remote = remote_get(pushremote_for_branch(branch, NULL));
+	if (!remote)
+		return NULL;
+
+	if (remote->push.nr) {
+		return apply_refspecs(&remote->push, branch->refname);
+	}
+
+	if (remote->mirror)
+		return branch->refname;
+
+	switch (push_default) {
+	case PUSH_DEFAULT_NOTHING:
+		return NULL;
+
+	case PUSH_DEFAULT_MATCHING:
+	case PUSH_DEFAULT_CURRENT:
+		return branch->refname;
+
+	case PUSH_DEFAULT_UPSTREAM:
+		if (branch && branch->merge && branch->merge[0] &&
+		    branch->merge[0]->dst)
+			return branch->merge[0]->src;
+		else
+			return NULL;
+
+	case PUSH_DEFAULT_UNSPECIFIED:
+	case PUSH_DEFAULT_SIMPLE:
+		{
+			const char *up, *cur;
+
+			up = branch_get_upstream(branch, NULL);
+			cur = tracking_for_push_dest(remote, branch->refname, NULL);
+			if (up && cur && !strcmp(cur, up))
+				return branch->refname;
+			else
+				return NULL;
+
+		}
+	}
+	BUG("unhandled push situation");
+}
+
+/**
+ * Return the tracking branch, as in %(push), that corresponds to the ref we
+ * would push to given a bare `git push` while `branch` is checked out.
+ * See also branch_get_push_remoteref above.
+ */
 static const char *branch_get_push_1(struct branch *branch, struct strbuf *err)
 {
 	struct remote *remote;
@@ -1735,6 +1771,20 @@ static int ignore_symref_update(const char *refname)
 	return (flag & REF_ISSYMREF);
 }
 
+const char *remote_ref_for_branch(struct branch *branch, int for_push)
+{
+	if (branch) {
+		if (!for_push) {
+			if (branch->merge_nr) {
+				return branch->merge_name[0];
+			}
+		} else {
+			return branch_get_push_remoteref(branch);
+		}
+	}
+	return NULL;
+}
+
 /*
  * Create and return a list of (struct ref) consisting of copies of
  * each remote_ref that matches refspec.  refspec must be a pattern.

t/t6300-for-each-ref.sh

@@ -875,12 +875,46 @@ test_expect_success ':remotename and :remoteref' '
 			git for-each-ref --format="${pair%=*}" \
 				refs/heads/master >actual &&
 			test_cmp expect actual
-		done &&
+		done
-		git branch push-simple &&
+	)
-		git config branch.push-simple.pushRemote from &&
+'
-		actual="$(git for-each-ref \
+
+test_expect_success ':push:remoteref' '
+	git init push-tests &&
+	(
+		cd push-tests &&
+		test_commit initial &&
+		git remote add from fifth.coffee:blub &&
+		git config branch.master.remote from &&
+		actual="$(git -c push.default=simple for-each-ref \
 			--format="%(push:remotename),%(push:remoteref)" \
-			refs/heads/push-simple)" &&
+			refs/heads/master)" &&
+		test from, = "$actual" &&
+		git config branch.master.merge refs/heads/master &&
+		actual="$(git -c push.default=simple for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
+		test from,refs/heads/master = "$actual" &&
+		git config branch.master.merge refs/heads/other &&
+		actual="$(git -c push.default=simple for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
+		test from, = "$actual" &&
+		actual="$(git -c push.default=upstream for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
+		test from,refs/heads/other = "$actual" &&
+		actual="$(git -c push.default=current for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
+		test from,refs/heads/master = "$actual" &&
+		actual="$(git -c push.default=matching for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
+		test from,refs/heads/master = "$actual" &&
+		actual="$(git -c push.default=nothing for-each-ref \
+			--format="%(push:remotename),%(push:remoteref)" \
+			refs/heads/master)" &&
 		test from, = "$actual"
 	)
 '