[PATCH 2/2] parse-options: don't emit "ambiguous option" for aliases

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the option parsing machinery so that e.g. "clone --recurs ..."
doesn't error out because "clone" understands both "--recursive" and
"--recurse-submodules" to mean the same thing.

Initially "clone" just understood --recursive until the
--recurses-submodules alias was added in ccdd3da652 ("clone: Add the
--recurse-submodules option as alias for --recursive",
2010-11-04). Since bb62e0a99f ("clone: teach --recurse-submodules to
optionally take a pathspec", 2017-03-17) the longer form has been
promoted to the default.

But due to the way the options parsing machinery works this resulted
in the rather absurd situation of:

    $ git clone --recurs [...]
    error: ambiguous option: recurs (could be --recursive or --recurse-submodules)

Let's re-use the PARSE_OPT_NOCOMPLETE flag to mean "this option
doesn't contribute to abbreviation ambiguity". I was going to add a
new PARSE_OPT_NOABBREV flag, but it makes sense just to re-use
PARSE_OPT_NOCOMPLETE.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/clone.c          | 4 ++--
 parse-options.c          | 3 ++-
 parse-options.h          | 2 ++
 t/t0040-parse-options.sh | 5 +++++
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/builtin/clone.c b/builtin/clone.c
index 50bde99618..4dc26969a7 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -100,8 +100,8 @@ static struct option builtin_clone_options[] = {
 		    N_("setup as shared repository")),
 	{ OPTION_CALLBACK, 0, "recursive", &option_recurse_submodules,
 	  N_("pathspec"), N_("initialize submodules in the clone"),
-	  PARSE_OPT_OPTARG | PARSE_OPT_HIDDEN, recurse_submodules_cb,
-	  (intptr_t)"." },
+	  PARSE_OPT_OPTARG | PARSE_OPT_HIDDEN | PARSE_OPT_NOCOMPLETE,
+	  recurse_submodules_cb, (intptr_t)"." },
 	{ OPTION_CALLBACK, 0, "recurse-submodules", &option_recurse_submodules,
 	  N_("pathspec"), N_("initialize submodules in the clone"),
 	  PARSE_OPT_OPTARG, recurse_submodules_cb, (intptr_t)"." },
diff --git a/parse-options.c b/parse-options.c
index d6a291f705..84f3a2996f 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -294,7 +294,8 @@ static enum parse_opt_result parse_long_opt(
 		if (!rest) {
 			/* abbreviated? */
 			if (!(p->flags & PARSE_OPT_KEEP_UNKNOWN) &&
-			    !strncmp(long_name, arg, arg_end - arg)) {
+			    !strncmp(long_name, arg, arg_end - arg) &&
+			    !(options->flags & PARSE_OPT_NOCOMPLETE)) {
 is_abbreviated:
 				if (abbrev_option) {
 					/*
diff --git a/parse-options.h b/parse-options.h
index 74cce4e7fc..9362a397ae 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -96,6 +96,8 @@ typedef enum parse_opt_result parse_opt_ll_cb(struct parse_opt_ctx_t *ctx,
  *				Useful for options with multiple parameters.
  *   PARSE_OPT_NOCOMPLETE: by default all visible options are completable
  *			   by git-completion.bash. This option suppresses that.
+ *			   Will also skip this option when abbreviation is
+ *			   considered. See core.abbreviatedOptions.
  *   PARSE_OPT_COMP_ARG: this option forces to git-completion.bash to
  *			 complete an option as --name= not --name even if
  *			 the option takes optional argument.
diff --git a/t/t0040-parse-options.sh b/t/t0040-parse-options.sh
index 19685d1582..c1ea50aa85 100755
--- a/t/t0040-parse-options.sh
+++ b/t/t0040-parse-options.sh
@@ -236,6 +236,11 @@ test_expect_success 'abbreviated options configured with core.abbreviatedOptions
 	git -c core.abbreviatedOptions=true init --ba C
 '
 
+test_expect_success 'NOCOMPLETE options do not contribute to abbreviation' '
+	test_when_finished "rm -rf A" &&
+	GIT_TEST_ABBREVIATED_OPTIONS=true git clone --recurs . A
+'
+
 cat >typo.err <<\EOF
 error: did you mean `--boolean` (with two dashes ?)
 EOF
-- 
2.21.0.360.g471c308f928