Merge branch 'mm/simple-push'

New users tend to work on one branch at a time and push the result
out. The current and upstream modes of push is a more suitable default
mode than matching mode for these people, but neither is surprise-free
depending on how the project is set up. Introduce a "simple" mode that
is a subset of "upstream" but only works when the branch is named the same
between the remote and local repositories.

The plan is to make it the new default when push.default is not
configured.

By Matthieu Moy (5) and others
* mm/simple-push:
  push.default doc: explain simple after upstream
  push: document the future default change for push.default (matching -> simple)
  t5570: use explicit push refspec
  push: introduce new push.default mode "simple"
  t5528-push-default.sh: add helper functions
  Undocument deprecated alias 'push.default=tracking'
  Documentation: explain push.default option a bit more

Documentation/config.txt

@@ -1683,12 +1683,30 @@ push.default::
 	line. Possible values are:
 +
 * `nothing` - do not push anything.
-* `matching` - push all matching branches.
-  All branches having the same name in both ends are considered to be
-  matching. This is the default.
+* `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` - deprecated synonym for `upstream`.
+  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.
+* `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.
+  +
+  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

builtin/push.c

@@ -76,7 +76,44 @@ static int push_url_of_remote(struct remote *remote, const char ***url_p)
 	return remote->url_nr;
 }
 
-static void setup_push_upstream(struct remote *remote)
+static NORETURN int die_push_simple(struct branch *branch, struct remote *remote) {
+	/*
+	 * There's no point in using shorten_unambiguous_ref here,
+	 * as the ambiguity would be on the remote side, not what
+	 * we have locally. Plus, this is supposed to be the simple
+	 * mode. If the user is doing something crazy like setting
+	 * upstream to a non-branch, we should probably be showing
+	 * them the big ugly fully qualified ref.
+	 */
+	const char *advice_maybe = "";
+	const char *short_upstream =
+		skip_prefix(branch->merge[0]->src, "refs/heads/");
+
+	if (!short_upstream)
+		short_upstream = branch->merge[0]->src;
+	/*
+	 * Don't show advice for people who explicitely set
+	 * push.default.
+	 */
+	if (push_default == PUSH_DEFAULT_UNSPECIFIED)
+		advice_maybe = _("\n"
+				 "To choose either option permanently, "
+				 "see push.default in 'git help config'.");
+	die(_("The upstream branch of your current branch does not match\n"
+	      "the name of your current branch.  To push to the upstream branch\n"
+	      "on the remote, use\n"
+	      "\n"
+	      "    git push %s HEAD:%s\n"
+	      "\n"
+	      "To push to the branch of the same name on the remote, use\n"
+	      "\n"
+	      "    git push %s %s\n"
+	      "%s"),
+	    remote->name, short_upstream,
+	    remote->name, branch->name, advice_maybe);
+}
+
+static void setup_push_upstream(struct remote *remote, int simple)
 {
 	struct strbuf refspec = STRBUF_INIT;
 	struct branch *branch = branch_get(NULL);
@@ -103,6 +140,8 @@ static void setup_push_upstream(struct remote *remote)
 		      "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);
@@ -119,8 +158,12 @@ static void setup_default_push_refspecs(struct remote *remote)
 		add_refspec(":");
 		break;
 
+	case PUSH_DEFAULT_SIMPLE:
+		setup_push_upstream(remote, 1);
+		break;
+
 	case PUSH_DEFAULT_UPSTREAM:
-		setup_push_upstream(remote);
+		setup_push_upstream(remote, 0);
 		break;
 
 	case PUSH_DEFAULT_CURRENT:

cache.h

@@ -580,6 +580,7 @@ enum rebase_setup_type {
 enum push_default_type {
 	PUSH_DEFAULT_NOTHING = 0,
 	PUSH_DEFAULT_MATCHING,
+	PUSH_DEFAULT_SIMPLE,
 	PUSH_DEFAULT_UPSTREAM,
 	PUSH_DEFAULT_CURRENT,
 	PUSH_DEFAULT_UNSPECIFIED

config.c

@@ -835,6 +835,8 @@ static int git_default_push_config(const char *var, const char *value)
 			push_default = PUSH_DEFAULT_NOTHING;
 		else if (!strcmp(value, "matching"))
 			push_default = PUSH_DEFAULT_MATCHING;
+		else if (!strcmp(value, "simple"))
+			push_default = PUSH_DEFAULT_SIMPLE;
 		else if (!strcmp(value, "upstream"))
 			push_default = PUSH_DEFAULT_UPSTREAM;
 		else if (!strcmp(value, "tracking")) /* deprecated */
@@ -843,8 +845,8 @@ static int git_default_push_config(const char *var, const char *value)
 			push_default = PUSH_DEFAULT_CURRENT;
 		else {
 			error("Malformed value for %s: %s", var, value);
-			return error("Must be one of nothing, matching, "
-				     "tracking or current.");
+			return error("Must be one of nothing, matching, simple, "
+				     "upstream or current.");
 		}
 		return 0;
 	}

t/t5528-push-default.sh

@@ -13,16 +13,36 @@ test_expect_success 'setup bare remotes' '
 	git push parent2 HEAD
 '
 
+# $1 = local revision
+# $2 = remote revision (tested to be equal to the local one)
+check_pushed_commit () {
+	git log -1 --format='%h %s' "$1" >expect &&
+	git --git-dir=repo1 log -1 --format='%h %s' "$2" >actual &&
+	test_cmp expect actual
+}
+
+# $1 = push.default value
+# $2 = expected target branch for the push
+test_push_success () {
+	git -c push.default="$1" push &&
+	check_pushed_commit HEAD "$2"
+}
+
+# $1 = push.default value
+# check that push fails and does not modify any remote branch
+test_push_failure () {
+	git --git-dir=repo1 log --no-walk --format='%h %s' --all >expect &&
+	test_must_fail git -c push.default="$1" push &&
+	git --git-dir=repo1 log --no-walk --format='%h %s' --all >actual &&
+	test_cmp expect actual
+}
+
 test_expect_success '"upstream" pushes to configured upstream' '
 	git checkout master &&
 	test_config branch.master.remote parent1 &&
 	test_config branch.master.merge refs/heads/foo &&
-	test_config push.default upstream &&
 	test_commit two &&
-	git push &&
-	echo two >expect &&
-	git --git-dir=repo1 log -1 --format=%s foo >actual &&
-	test_cmp expect actual
+	test_push_success upstream foo
 '
 
 test_expect_success '"upstream" does not push on unconfigured remote' '
@@ -30,7 +50,7 @@ test_expect_success '"upstream" does not push on unconfigured remote' '
 	test_unconfig branch.master.remote &&
 	test_config push.default upstream &&
 	test_commit three &&
-	test_must_fail git push
+	test_push_failure upstream
 '
 
 test_expect_success '"upstream" does not push on unconfigured branch' '
@@ -39,7 +59,7 @@ test_expect_success '"upstream" does not push on unconfigured branch' '
 	test_unconfig branch.master.merge &&
 	test_config push.default upstream
 	test_commit four &&
-	test_must_fail git push
+	test_push_failure upstream
 '
 
 test_expect_success '"upstream" does not push when remotes do not match' '
@@ -51,4 +71,48 @@ test_expect_success '"upstream" does not push when remotes do not match' '
 	test_must_fail git push parent2
 '
 
+test_expect_success 'push from/to new branch with upstream, matching and simple' '
+	git checkout -b new-branch &&
+	test_push_failure simple &&
+	test_push_failure matching &&
+	test_push_failure upstream
+'
+
+test_expect_success 'push from/to new branch with current creates remote branch' '
+	test_config branch.new-branch.remote repo1 &&
+	git checkout new-branch &&
+	test_push_success current new-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_failure upstream
+'
+
+test_expect_success 'push to existing branch, upstream configured with same name' '
+	test_config branch.master.remote repo1 &&
+	test_config branch.master.merge refs/heads/master &&
+	git checkout master &&
+	test_commit six &&
+	test_push_success upstream master &&
+	test_commit seven &&
+	test_push_success simple master
+'
+
+test_expect_success 'push to existing branch, upstream configured with different name' '
+	test_config branch.master.remote repo1 &&
+	test_config branch.master.merge refs/heads/other-name &&
+	git checkout master &&
+	test_commit eight &&
+	test_push_success upstream other-name &&
+	test_commit nine &&
+	test_push_failure simple &&
+	git --git-dir=repo1 log -1 --format="%h %s" "other-name" >expect-other-name &&
+	test_push_success current master &&
+	git --git-dir=repo1 log -1 --format="%h %s" "other-name" >actual-other-name &&
+	test_cmp expect-other-name actual-other-name
+'
+
 test_done

t/t5570-git-daemon.sh

@@ -103,14 +103,12 @@ test_remote_error()
 		esac
 	done
 
-	if test $# -ne 3
-	then
-		error "invalid number of arguments"
-	fi
-
+	msg=$1
+	shift
 	cmd=$1
-	repo=$2
-	msg=$3
+	shift
+	repo=$1
+	shift || error "invalid number of arguments"
 
 	if test -x "$GIT_DAEMON_DOCUMENT_ROOT_PATH/$repo"
 	then
@@ -122,7 +120,7 @@ test_remote_error()
 		fi
 	fi
 
-	test_must_fail git "$cmd" "$GIT_DAEMON_URL/$repo" 2>output &&
+	test_must_fail git "$cmd" "$GIT_DAEMON_URL/$repo" "$@" 2>output &&
 	echo "fatal: remote error: $msg: /$repo" >expect &&
 	test_cmp expect output
 	ret=$?
@@ -131,18 +129,18 @@ test_remote_error()
 }
 
 msg="access denied or repository not exported"
-test_expect_success 'clone non-existent' "test_remote_error    clone nowhere.git '$msg'"
-test_expect_success 'push disabled'      "test_remote_error    push  repo.git    '$msg'"
-test_expect_success 'read access denied' "test_remote_error -x fetch repo.git    '$msg'"
-test_expect_success 'not exported'       "test_remote_error -n fetch repo.git    '$msg'"
+test_expect_success 'clone non-existent' "test_remote_error    '$msg' clone nowhere.git    "
+test_expect_success 'push disabled'      "test_remote_error    '$msg' push  repo.git master"
+test_expect_success 'read access denied' "test_remote_error -x '$msg' fetch repo.git       "
+test_expect_success 'not exported'       "test_remote_error -n '$msg' fetch repo.git       "
 
 stop_git_daemon
 start_git_daemon --informative-errors
 
-test_expect_success 'clone non-existent' "test_remote_error    clone nowhere.git 'no such repository'"
-test_expect_success 'push disabled'      "test_remote_error    push  repo.git    'service not enabled'"
-test_expect_success 'read access denied' "test_remote_error -x fetch repo.git    'no such repository'"
-test_expect_success 'not exported'       "test_remote_error -n fetch repo.git    'repository not exported'"
+test_expect_success 'clone non-existent' "test_remote_error    'no such repository'      clone nowhere.git    "
+test_expect_success 'push disabled'      "test_remote_error    'service not enabled'     push  repo.git master"
+test_expect_success 'read access denied' "test_remote_error -x 'no such repository'      fetch repo.git       "
+test_expect_success 'not exported'       "test_remote_error -n 'repository not exported' fetch repo.git       "
 
 stop_git_daemon
 test_done