clone: send server options when using protocol v2

Commit 5e3548ef16 ("fetch: send server options when using protocol v2",
2018-04-24) taught "fetch" the ability to send server options when using
protocol v2, but not "clone". This ability is triggered by "-o" or
"--server-option".

Teach "clone" the same ability, except that because "clone" already
has "-o" for another parameter, teach "clone" only to receive
"--server-option".

Explain in the documentation, both for clone and for fetch, that server
handling of server options are server-specific. This is similar to
receive-pack's handling of push options - currently, they are just sent
to hooks to interpret as they see fit.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/fetch-options.txt

@@ -216,7 +216,8 @@ endif::git-pull[]
 --server-option=<option>::
 	Transmit the given string to the server when communicating using
 	protocol version 2.  The given string must not contain a NUL or LF
-	character.
+	character.  The server's handling of server options, including
+	unknown ones, is server-specific.
 	When multiple `--server-option=<option>` are given, they are all
 	sent to the other side in the order listed on the command line.
 

Documentation/git-clone.txt

@@ -131,6 +131,14 @@ objects from the source repository into a pack in the cloned repository.
 	is specified. This flag forces progress status even if the
 	standard error stream is not directed to a terminal.
 
+--server-option=<option>::
+	Transmit the given string to the server when communicating using
+	protocol version 2.  The given string must not contain a NUL or LF
+	character.  The server's handling of server options, including
+	unknown ones, is server-specific.
+	When multiple `--server-option=<option>` are given, they are all
+	sent to the other side in the order listed on the command line.
+
 --no-checkout::
 -n::
 	No checkout of HEAD is performed after the clone is complete.

builtin/clone.c

@@ -66,6 +66,7 @@ static int option_dissociate;
 static int max_jobs = -1;
 static struct string_list option_recurse_submodules = STRING_LIST_INIT_NODUP;
 static struct list_objects_filter_options filter_options;
+static struct string_list server_options = STRING_LIST_INIT_NODUP;
 
 static int recurse_submodules_cb(const struct option *opt,
 				 const char *arg, int unset)
@@ -137,6 +138,8 @@ static struct option builtin_clone_options[] = {
 		   N_("separate git dir from working tree")),
 	OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
 			N_("set config inside the new repository")),
+	OPT_STRING_LIST(0, "server-option", &server_options,
+			N_("server-specific"), N_("option to transmit")),
 	OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
 			TRANSPORT_FAMILY_IPV4),
 	OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
@@ -1136,6 +1139,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		transport_set_option(transport, TRANS_OPT_UPLOADPACK,
 				     option_upload_pack);
 
+	if (server_options.nr)
+		transport->server_options = &server_options;
+
 	if (filter_options.choice) {
 		struct strbuf expanded_filter_spec = STRBUF_INIT;
 		expand_list_objects_filter_spec(&filter_options,

t/t5702-protocol-v2.sh

@@ -270,6 +270,28 @@ test_expect_success 'warn if using server-option with fetch with legacy protocol
 	test_i18ngrep "server options require protocol version 2 or later" err
 '
 
+test_expect_success 'server-options are sent when cloning' '
+	test_when_finished "rm -rf log myclone" &&
+
+	GIT_TRACE_PACKET="$(pwd)/log" git -c protocol.version=2 \
+		clone --server-option=hello --server-option=world \
+		"file://$(pwd)/file_parent" myclone &&
+
+	grep "server-option=hello" log &&
+	grep "server-option=world" log
+'
+
+test_expect_success 'warn if using server-option with clone with legacy protocol' '
+	test_when_finished "rm -rf myclone" &&
+
+	test_must_fail env GIT_TEST_PROTOCOL_VERSION=0 git -c protocol.version=0 \
+		clone --server-option=hello --server-option=world \
+		"file://$(pwd)/file_parent" myclone 2>err &&
+
+	test_i18ngrep "see protocol.version in" err &&
+	test_i18ngrep "server options require protocol version 2 or later" err
+'
+
 test_expect_success 'upload-pack respects config using protocol v2' '
 	git init server &&
 	write_script server/.git/hook <<-\EOF &&