[PATCH 5/5] config: add --type=bool-or-auto switch

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

Now that we're using git_config_tristate() internally let's expose it
via "git config" like we do "bool", "int" etc for completeness, and so
that we can easily test it.

Unlike the --type=bool-or-str option added in dbd8c09bfe (mergetool:
allow auto-merge for meld to follow the vim-diff behavior, 2020-05-07)
we don't have or anticipate any in-tree user of this except the tests.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-config.txt |  4 +++
 builtin/config.c             | 19 ++++++++++++++
 t/t1300-config.sh            | 49 ++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)

diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index 4ae9ef210c..1af8222e82 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -189,6 +189,10 @@ Valid `<type>`'s include:
   above.
 - 'bool-or-str: canonicalize according to either 'bool' (as described
   above), or emit the value as-is.
+- 'bool-or-auto: canonicalize according to either 'bool', as described
+  above, or whether the value is "auto". This is used by various
+  "tristate" variables such as `core.restrictInheritedHandles`,
+  `format.numbered` etc.
 - 'path': canonicalize by adding a leading `~` to the value of `$HOME` and
   `~user` to the home directory for the specified user. This specifier has no
   effect when setting the value (but you can use `git config section.variable
diff --git a/builtin/config.c b/builtin/config.c
index f71fa39b38..039a4f0961 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -68,6 +68,7 @@ static int fixed_value;
 #define TYPE_EXPIRY_DATE	5
 #define TYPE_COLOR		6
 #define TYPE_BOOL_OR_STR	7
+#define TYPE_BOOL_OR_AUTO	8
 
 #define OPT_CALLBACK_VALUE(s, l, v, h, i) \
 	{ OPTION_CALLBACK, (s), (l), (v), NULL, (h), PARSE_OPT_NOARG | \
@@ -99,6 +100,8 @@ static int option_parse_type(const struct option *opt, const char *arg,
 			new_type = TYPE_BOOL_OR_INT;
 		else if (!strcmp(arg, "bool-or-str"))
 			new_type = TYPE_BOOL_OR_STR;
+		else if (!strcmp(arg, "bool-or-auto"))
+			new_type = TYPE_BOOL_OR_AUTO;
 		else if (!strcmp(arg, "path"))
 			new_type = TYPE_PATH;
 		else if (!strcmp(arg, "expiry-date"))
@@ -156,6 +159,7 @@ static struct option builtin_config_options[] = {
 	OPT_CALLBACK_VALUE(0, "int", &type, N_("value is decimal number"), TYPE_INT),
 	OPT_CALLBACK_VALUE(0, "bool-or-int", &type, N_("value is --bool or --int"), TYPE_BOOL_OR_INT),
 	OPT_CALLBACK_VALUE(0, "bool-or-str", &type, N_("value is --bool or string"), TYPE_BOOL_OR_STR),
+	/* No bool-or-auto! The --<type> form is deprecated in favor of --type=<what> */
 	OPT_CALLBACK_VALUE(0, "path", &type, N_("value is a path (file or directory name)"), TYPE_PATH),
 	OPT_CALLBACK_VALUE(0, "expiry-date", &type, N_("value is an expiry date"), TYPE_EXPIRY_DATE),
 	OPT_GROUP(N_("Other")),
@@ -263,6 +267,12 @@ static int format_config(struct strbuf *buf, const char *key_, const char *value
 				strbuf_addstr(buf, value_);
 			else
 				strbuf_addstr(buf, v ? "true" : "false");
+		} else if (type == TYPE_BOOL_OR_AUTO) {
+			int v = git_config_tristate(key_, value_);
+			if (v == 2)
+				strbuf_addstr(buf, "auto");
+			else
+				strbuf_addstr(buf, v ? "true" : "false");
 		} else if (type == TYPE_PATH) {
 			const char *v;
 			if (git_config_pathname(&v, key_, value_) < 0)
@@ -435,6 +445,15 @@ static char *normalize_value(const char *key, const char *value)
 		else
 			return xstrdup(v ? "true" : "false");
 	}
+	if (type == TYPE_BOOL_OR_AUTO) {
+		int v = git_parse_maybe_tristate(value);
+		if (v < 0)
+			return xstrdup(value);
+		else if (v == 2)
+			xstrdup("auto");
+		else
+			return xstrdup(v ? "true" : "false");
+	}
 	if (type == TYPE_COLOR) {
 		char v[COLOR_MAXLEN];
 		if (git_config_color(v, key, value))
diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index a002ec5644..952d9e9ed9 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -874,6 +874,55 @@ test_expect_success 'get --bool-or-str' '
 	test_cmp expect actual
 '
 
+test_expect_success 'there is no --bool-or-auto, --<type> is deprecated in favor of --type=<type>' '
+	test_expect_code 129 git config --bool-or-auto
+'
+
+test_expect_success 'get --type=bool-or-auto' '
+	cat >.git/config <<-\EOF &&
+	[bool]
+	true1
+	true2 = true
+	false = false
+	[int]
+	int1 = 0
+	int2 = 1
+	int3 = -1
+	[string]
+	string1 = hello
+	string2 = there you
+	[auto]
+	auto1 = auto
+	auto2 = AUTO
+	[bad-auto]
+	bad-auto1 = AUTOMATIC
+	EOF
+	cat >expect <<-\EOF &&
+	true
+	true
+	false
+	false
+	true
+	true
+	auto
+	auto
+	EOF
+	{
+		git config --type=bool-or-auto bool.true1 &&
+		git config --type=bool-or-auto bool.true2 &&
+		git config --type=bool-or-auto bool.false &&
+		git config --type=bool-or-auto int.int1 &&
+		git config --type=bool-or-auto int.int2 &&
+		git config --type=bool-or-auto int.int3 &&
+		git config --type=bool-or-auto auto.auto1 &&
+		git config --type=bool-or-auto auto.auto2
+	} >actual &&
+	test_cmp expect actual &&
+
+	test_must_fail git config --type=bool-or-auto --get bad-auto.bad-auto1 2>err &&
+	grep "bad tristate config value" err
+'
+
 cat >expect <<\EOF
 [bool]
 	true1 = true
-- 
2.31.1.527.g9b8f7de2547