[PATCH v3 1/2 / RFC] builtin/branch: stop supporting the use of --set-upstream option

[Kaartic Sivaraam <kaarticsivaraam91196@gmail.com>]

The '--set-upstream' option of branch was deprecated in,

    b347d06bf branch: deprecate --set-upstream and show help if we
    detect possible mistaken use (Thu, 30 Aug 2012 19:23:13 +0200)

It was deprecated for the reasons specified in the commit message of the
referenced commit.

Make 'branch' die with an appropraite error message when the '--set-upstream'
option is used.

Note that there's a reason behind "dying with an error message" instead of
"not accepting the option". 'git branch' would *accept* '--set-upstream'
even after it's removal as a consequence of,

        Unique prefix can be abbrievated in option names

                          AND

    '--set-upstream' is a unique prefix of '--set-upstream-to'
       (when the '--set-upstream' option has been removed)

In order to smooth the transition for users and to avoid them being affected
by the "prefix issue" it was decided to make branch die when seeing the
'--set-upstream' flag for a few years and let the users know that it would be
removed some time in the future.

The before/after behaviour for a simple case follows,

    $ git remote
    origin

Before,

    $ git branch
    * master

    $ git branch --set-upstream origin/master
    The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
    Branch origin/master set up to track local branch master.

    $ echo $?
    0

    $ git branch
    * master
      origin/master

After,

    $ git branch
    * master

    $ git branch --set-upstream origin/master
    fatal: the '--set-upstream' flag is no longer supported and will be removed. Consider using '--track' or '--set-upstream-to'

    $ echo $?
    128

    $ git branch
    * master

Signed-off-by: Kaartic Sivaraam <kaarticsivaraam91196@gmail.com>
---
 Changes in v3:
 
    A few tweaks to the following:
     * Commit message
     * Error message (the one shown when '--set-upstream' is seen)
     * Updated the corresponding message in the options structure
     * Documentation

 A query,

    I see the following code in the code path a little above the die statement
    added in this change,

            if (!strcmp(argv[0], "HEAD"))
    		    	die(_("it does not make sense to create 'HEAD' manually"));

    It does seem to be doing quite a nice job of avoiding an ambiguity that could
    have bad consequences but it's still possible to create a branch named 'HEAD'
    using the '-b' option of 'checkout'. Should 'git checkout -b HEAD' actually
    fail(it does not currently) for the same reason 'git branch HEAD' fails?

    My guess is that people would use 'git checkout -b <new_branch_name> <starting_point>'
    more than it's 'git branch' counterpart.    


 Documentation/git-branch.txt |  8 +++----
 builtin/branch.c             | 23 ++------------------
 t/t3200-branch.sh            | 50 ++++----------------------------------------
 t/t6040-tracking-info.sh     | 16 +++++++-------
 4 files changed, 18 insertions(+), 79 deletions(-)

diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index 81bd0a7b7..93ee05c55 100644
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -195,10 +195,10 @@ start-point is either a local or remote-tracking branch.
 	branch.autoSetupMerge configuration variable is true.
 
 --set-upstream::
-	If specified branch does not exist yet or if `--force` has been
-	given, acts exactly like `--track`. Otherwise sets up configuration
-	like `--track` would when creating the branch, except that where
-	branch points to is not changed.
+	As this option has confusing syntax it's no longer supported. Please use
+  --track or --set-upstream-to  instead.
++
+Note: This could possibly become an alias of --set-upstream-to in the future.
 
 -u <upstream>::
 --set-upstream-to=<upstream>::
diff --git a/builtin/branch.c b/builtin/branch.c
index a3bd2262b..b92070393 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -557,7 +557,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT__QUIET(&quiet, N_("suppress informational messages")),
 		OPT_SET_INT('t', "track",  &track, N_("set up tracking mode (see git-pull(1))"),
 			BRANCH_TRACK_EXPLICIT),
-		OPT_SET_INT( 0, "set-upstream",  &track, N_("change upstream info"),
+		OPT_SET_INT( 0, "set-upstream",  &track, N_("no longer supported"),
 			BRANCH_TRACK_OVERRIDE),
 		OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),
 		OPT_BOOL(0, "unset-upstream", &unset_upstream, N_("Unset the upstream info")),
@@ -755,8 +755,6 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		strbuf_release(&buf);
 	} else if (argc > 0 && argc <= 2) {
 		struct branch *branch = branch_get(argv[0]);
-		int branch_existed = 0, remote_tracking = 0;
-		struct strbuf buf = STRBUF_INIT;
 
 		if (!strcmp(argv[0], "HEAD"))
 			die(_("it does not make sense to create 'HEAD' manually"));
@@ -768,28 +766,11 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			die(_("-a and -r options to 'git branch' do not make sense with a branch name"));
 
 		if (track == BRANCH_TRACK_OVERRIDE)
-			fprintf(stderr, _("The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to\n"));
+			die(_("the '--set-upstream' option is no longer supported. Please use '--track' or '--set-upstream-to' instead."));
 
-		strbuf_addf(&buf, "refs/remotes/%s", branch->name);
-		remote_tracking = ref_exists(buf.buf);
-		strbuf_release(&buf);
-
-		branch_existed = ref_exists(branch->refname);
 		create_branch(argv[0], (argc == 2) ? argv[1] : head,
 			      force, reflog, 0, quiet, track);
 
-		/*
-		 * We only show the instructions if the user gave us
-		 * one branch which doesn't exist locally, but is the
-		 * name of a remote-tracking branch.
-		 */
-		if (argc == 1 && track == BRANCH_TRACK_OVERRIDE &&
-		    !branch_existed && remote_tracking) {
-			fprintf(stderr, _("\nIf you wanted to make '%s' track '%s', do this:\n\n"), head, branch->name);
-			fprintf(stderr, "    git branch -d %s\n", branch->name);
-			fprintf(stderr, "    git branch --set-upstream-to %s\n", branch->name);
-		}
-
 	} else
 		usage_with_options(builtin_branch_usage, options);
 
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index dd37ac47c..249be4b1a 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -561,7 +561,8 @@ test_expect_success 'use --set-upstream-to modify a particular branch' '
 	git branch my13 &&
 	git branch --set-upstream-to master my13 &&
 	test "$(git config branch.my13.remote)" = "." &&
-	test "$(git config branch.my13.merge)" = "refs/heads/master"
+	test "$(git config branch.my13.merge)" = "refs/heads/master" &&
+	git branch --unset-upstream my13
 '
 
 test_expect_success '--unset-upstream should fail if given a non-existent branch' '
@@ -605,38 +606,8 @@ test_expect_success 'test --unset-upstream on a particular branch' '
 	test_must_fail git config branch.my14.merge
 '
 
-test_expect_success '--set-upstream shows message when creating a new branch that exists as remote-tracking' '
-	git update-ref refs/remotes/origin/master HEAD &&
-	git branch --set-upstream origin/master 2>actual &&
-	test_when_finished git update-ref -d refs/remotes/origin/master &&
-	test_when_finished git branch -d origin/master &&
-	cat >expected <<EOF &&
-The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
-
-If you wanted to make '"'master'"' track '"'origin/master'"', do this:
-
-    git branch -d origin/master
-    git branch --set-upstream-to origin/master
-EOF
-	test_i18ncmp expected actual
-'
-
-test_expect_success '--set-upstream with two args only shows the deprecation message' '
-	git branch --set-upstream master my13 2>actual &&
-	test_when_finished git branch --unset-upstream master &&
-	cat >expected <<EOF &&
-The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
-EOF
-	test_i18ncmp expected actual
-'
-
-test_expect_success '--set-upstream with one arg only shows the deprecation message if the branch existed' '
-	git branch --set-upstream my13 2>actual &&
-	test_when_finished git branch --unset-upstream my13 &&
-	cat >expected <<EOF &&
-The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
-EOF
-	test_i18ncmp expected actual
+test_expect_success '--set-upstream fails' '
+    test_must_fail git branch --set-upstream origin/master
 '
 
 test_expect_success '--set-upstream-to notices an error to set branch as own upstream' '
@@ -961,19 +932,6 @@ test_expect_success 'attempt to delete a branch merged to its base' '
 	test_must_fail git branch -d my10
 '
 
-test_expect_success 'use set-upstream on the current branch' '
-	git checkout master &&
-	git --bare init myupstream.git &&
-	git push myupstream.git master:refs/heads/frotz &&
-	git remote add origin myupstream.git &&
-	git fetch &&
-	git branch --set-upstream master origin/frotz &&
-
-	test "z$(git config branch.master.remote)" = "zorigin" &&
-	test "z$(git config branch.master.merge)" = "zrefs/heads/frotz"
-
-'
-
 test_expect_success 'use --edit-description' '
 	write_script editor <<-\EOF &&
 		echo "New contents" >"$1"
diff --git a/t/t6040-tracking-info.sh b/t/t6040-tracking-info.sh
index 97a07655a..4b522f456 100755
--- a/t/t6040-tracking-info.sh
+++ b/t/t6040-tracking-info.sh
@@ -188,35 +188,35 @@ test_expect_success 'fail to track annotated tags' '
 	test_must_fail git checkout heavytrack
 '
 
-test_expect_success 'setup tracking with branch --set-upstream on existing branch' '
+test_expect_success 'setup tracking with branch --set-upstream-to on existing branch' '
 	git branch from-master master &&
 	test_must_fail git config branch.from-master.merge > actual &&
-	git branch --set-upstream from-master master &&
+	git branch --set-upstream-to master from-master &&
 	git config branch.from-master.merge > actual &&
 	grep -q "^refs/heads/master$" actual
 '
 
-test_expect_success '--set-upstream does not change branch' '
+test_expect_success '--set-upstream-to does not change branch' '
 	git branch from-master2 master &&
 	test_must_fail git config branch.from-master2.merge > actual &&
 	git rev-list from-master2 &&
 	git update-ref refs/heads/from-master2 from-master2^ &&
 	git rev-parse from-master2 >expect2 &&
-	git branch --set-upstream from-master2 master &&
+	git branch --set-upstream-to master from-master2 &&
 	git config branch.from-master.merge > actual &&
 	git rev-parse from-master2 >actual2 &&
 	grep -q "^refs/heads/master$" actual &&
 	cmp expect2 actual2
 '
 
-test_expect_success '--set-upstream @{-1}' '
-	git checkout from-master &&
+test_expect_success '--set-upstream-to @{-1}' '
+	git checkout follower &&
 	git checkout from-master2 &&
 	git config branch.from-master2.merge > expect2 &&
-	git branch --set-upstream @{-1} follower &&
+	git branch --set-upstream-to @{-1} from-master &&
 	git config branch.from-master.merge > actual &&
 	git config branch.from-master2.merge > actual2 &&
-	git branch --set-upstream from-master follower &&
+	git branch --set-upstream-to follower from-master &&
 	git config branch.from-master.merge > expect &&
 	test_cmp expect2 actual2 &&
 	test_cmp expect actual
-- 
2.14.0.rc1.434.g6eded367a