[PATCH v4 2/3] submodule--helper: teach config subcommand --unset

[Denton Liu]

This teaches submodule--helper config the --unset option, which removes
the specified configuration key from the .gitmodule file.

Signed-off-by: Denton Liu <liu.den...@gmail.com>
---
 builtin/submodule--helper.c | 17 ++++++++++++-----
 t/t7411-submodule-config.sh |  9 +++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 0e140f176c..449e56f30c 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2147,17 +2147,22 @@ static int check_name(int argc, const char **argv, 
const char *prefix)
 static int module_config(int argc, const char **argv, const char *prefix)
 {
        enum {
-               CHECK_WRITEABLE = 1
+               CHECK_WRITEABLE = 1,
+               DO_UNSET = 2
        } command = 0;
 
        struct option module_config_options[] = {
                OPT_CMDMODE(0, "check-writeable", &command,
                            N_("check if it is safe to write to the .gitmodules 
file"),
                            CHECK_WRITEABLE),
+               OPT_CMDMODE(0, "unset", &command,
+                           N_("unset the config in the .gitmodules file"),
+                           DO_UNSET),
                OPT_END()
        };
        const char *const git_submodule_helper_usage[] = {
-               N_("git submodule--helper config name [value]"),
+               N_("git submodule--helper config <name> [<value>]"),
+               N_("git submodule--helper config --unset <name>"),
                N_("git submodule--helper config --check-writeable"),
                NULL
        };
@@ -2169,15 +2174,17 @@ static int module_config(int argc, const char **argv, 
const char *prefix)
                return is_writing_gitmodules_ok() ? 0 : -1;
 
        /* Equivalent to ACTION_GET in builtin/config.c */
-       if (argc == 2)
+       if (argc == 2 && command != DO_UNSET)
                return print_config_from_gitmodules(the_repository, argv[1]);
 
        /* Equivalent to ACTION_SET in builtin/config.c */
-       if (argc == 3) {
+       if (argc == 3 || (argc == 2 && command == DO_UNSET)) {
+               const char *value = (argc == 3) ? argv[2] : NULL;
+
                if (!is_writing_gitmodules_ok())
                        die(_("please make sure that the .gitmodules file is in 
the working tree"));
 
-               return config_set_in_gitmodules_file_gently(argv[1], argv[2]);
+               return config_set_in_gitmodules_file_gently(argv[1], value);
        }
 
        usage_with_options(git_submodule_helper_usage, module_config_options);
diff --git a/t/t7411-submodule-config.sh b/t/t7411-submodule-config.sh
index 89690b7adb..fcc0fb82d8 100755
--- a/t/t7411-submodule-config.sh
+++ b/t/t7411-submodule-config.sh
@@ -142,6 +142,15 @@ test_expect_success 'reading submodules config from the 
working tree with "submo
        )
 '
 
+test_expect_success 'unsetting submodules config from the working tree with 
"submodule--helper config --unset"' '
+       (cd super &&
+               git submodule--helper config --unset submodule.submodule.url &&
+               git submodule--helper config submodule.submodule.url >actual &&
+               test_must_be_empty actual
+       )
+'
+
+
 test_expect_success 'writing submodules config with "submodule--helper 
config"' '
        (cd super &&
                echo "new_url" >expect &&
-- 
2.20.1.522.g5f42c252e9