[PATCH v2 1/2] rebase: remove completely useless -C option

["Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>]

From: Elijah Newren <newren@gmail.com>

The `-C` option to rebase was introduced with 67dad687ad ("add -C[NUM]
to git-am", 2007-02-08).  Based on feedback on the patch, the author
added the -C option not just to git-am but also to git-rebase.  But did
it such that the option was just passed through to git-am (which passes
it along to git-apply), with no corresponding option to format-patch.

As per the git-apply documentation for the `-C` option:
    Ensure at least <n> lines of surrounding context match...When fewer
    lines of surrounding context exist they all must match.

The fact that format-patch was not passed a -U option to increase the
number of context lines meant that there would still only be 3 lines of
context to match on.  So, anyone attempting to use this option in
git-rebase would just be spinning their wheels and wasting time.  I was
one such user a number of years ago.

Since this option can at best waste users time and is nothing more than
a confusing no-op, and has never been anything other than a confusing
no-op, and no one has ever bothered to create a testcase for it that
goes beyond option parsing, simply excise the option.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 Documentation/git-rebase.txt           | 9 ---------
 builtin/rebase.c                       | 9 +--------
 t/t3406-rebase-message.sh              | 7 -------
 t/t3422-rebase-incompatible-options.sh | 1 -
 4 files changed, 1 insertion(+), 25 deletions(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index f9675bd24e6..412887deda7 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -416,14 +416,6 @@ include::rerere-options.txt[]
 	Allows the pre-rebase hook to run, which is the default.  This option can
 	be used to override `--no-verify`.  See also linkgit:githooks[5].
 
--C<n>::
-	Ensure at least `<n>` lines of surrounding context match before
-	and after each change.  When fewer lines of surrounding
-	context exist they all must match.  By default no context is
-	ever ignored.  Implies `--apply`.
-+
-See also INCOMPATIBLE OPTIONS below.
-
 --no-ff::
 --force-rebase::
 -f::
@@ -631,7 +623,6 @@ The following options:
 
  * --apply
  * --whitespace
- * -C
 
 are incompatible with the following options:
 
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 1481c5b6a5b..ace8bd4a41c 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1067,8 +1067,6 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 			 N_("ignore author date and use current date")),
 		OPT_HIDDEN_BOOL(0, "ignore-date", &options.ignore_date,
 				N_("synonym of --reset-author-date")),
-		OPT_PASSTHRU_ARGV('C', NULL, &options.git_am_opts, N_("n"),
-				  N_("passed to 'git apply'"), 0),
 		OPT_BOOL(0, "ignore-whitespace", &ignore_whitespace,
 			 N_("ignore changes in whitespace")),
 		OPT_PASSTHRU_ARGV(0, "whitespace", &options.git_am_opts,
@@ -1390,12 +1388,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		if (!strcmp(option, "--whitespace=fix") ||
 		    !strcmp(option, "--whitespace=strip"))
 			allow_preemptive_ff = 0;
-		else if (skip_prefix(option, "-C", &p)) {
-			while (*p)
-				if (!isdigit(*(p++)))
-					die(_("switch `C' expects a "
-					      "numerical value"));
-		} else if (skip_prefix(option, "--whitespace=", &p)) {
+		else if (skip_prefix(option, "--whitespace=", &p)) {
 			if (*p && strcmp(p, "warn") && strcmp(p, "nowarn") &&
 			    strcmp(p, "error") && strcmp(p, "error-all"))
 				die("Invalid whitespace option: '%s'", p);
diff --git a/t/t3406-rebase-message.sh b/t/t3406-rebase-message.sh
index ceca1600053..c8dca845dd7 100755
--- a/t/t3406-rebase-message.sh
+++ b/t/t3406-rebase-message.sh
@@ -78,13 +78,6 @@ test_expect_success 'rebase --onto outputs the invalid ref' '
 	test_i18ngrep "invalid-ref" err
 '
 
-test_expect_success 'error out early upon -C<n> or --whitespace=<bad>' '
-	test_must_fail git rebase -Cnot-a-number HEAD 2>err &&
-	test_i18ngrep "numerical value" err &&
-	test_must_fail git rebase --whitespace=bad HEAD 2>err &&
-	test_i18ngrep "Invalid whitespace option" err
-'
-
 write_reflog_expect () {
 	if test $mode = --apply
 	then
diff --git a/t/t3422-rebase-incompatible-options.sh b/t/t3422-rebase-incompatible-options.sh
index 6dabb05a2ad..ebcbd79ab8a 100755
--- a/t/t3422-rebase-incompatible-options.sh
+++ b/t/t3422-rebase-incompatible-options.sh
@@ -63,6 +63,5 @@ test_rebase_am_only () {
 }
 
 test_rebase_am_only --whitespace=fix
-test_rebase_am_only -C4
 
 test_done
-- 
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