submodule: get rid of `_save()`

We no longer have any setters which affect an instance, so
`git_submodule_save()` is no longer relevant.

include/git2/submodule.h

@@ -301,20 +301,6 @@ GIT_EXTERN(int) git_submodule_add_to_index(
 	int write_index);
 
 /**
- * Write submodule settings to .gitmodules file.
- *
- * This commits any in-memory changes to the submodule to the gitmodules
- * file on disk.  You may also be interested in `git_submodule_init()` which
- * writes submodule info to ".git/config" (which is better for local changes
- * to submodule settings) and/or `git_submodule_sync()` which writes
- * settings about remotes to the actual submodule repository.
- *
- * @param submodule The submodule to write.
- * @return 0 on success, <0 on failure.
- */
-GIT_EXTERN(int) git_submodule_save(git_submodule *submodule);
-
-/**
  * Get the containing repository for a submodule.
  *
  * This returns a pointer to the repository that contains the submodule.

src/submodule.c

@@ -764,44 +764,6 @@ const char *git_submodule_recurse_to_str(git_submodule_recurse_t recurse)
 	return NULL;
 }
 
-int git_submodule_save(git_submodule *submodule)
-{
-	int error = 0;
-	git_config_backend *mods;
-	git_buf key = GIT_BUF_INIT;
-
-	assert(submodule);
-
-	mods = open_gitmodules(submodule->repo, GITMODULES_CREATE);
-	if (!mods) {
-		giterr_set(GITERR_SUBMODULE,
-			"Adding submodules to a bare repository is not supported");
-		return -1;
-	}
-
-	if ((error = git_buf_printf(&key, "submodule.%s.", submodule->name)) < 0)
-		goto cleanup;
-
-	/* save values for path, url, update, ignore, fetchRecurseSubmodules */
-
-	if ((error = submodule_config_key_trunc_puts(&key, "path")) < 0 ||
-		(error = git_config_file_set_string(mods, key.ptr, submodule->path)) < 0)
-		goto cleanup;
-
-	/* update internal defaults */
-
-	submodule->ignore_default = submodule->ignore;
-	submodule->update_default = submodule->update;
-	submodule->fetch_recurse_default = submodule->fetch_recurse;
-	submodule->flags |= GIT_SUBMODULE_STATUS_IN_CONFIG;
-
-cleanup:
-	git_config_file_free(mods);
-	git_buf_free(&key);
-
-	return error;
-}
-
 git_repository *git_submodule_owner(git_submodule *submodule)
 {
 	assert(submodule);

tests/submodule/modify.c

@@ -194,12 +194,3 @@ void test_submodule_modify__set_url(void)
 	cl_assert_equal_s(SM_LIBGIT2_URL, git_submodule_url(sm));
 	git_submodule_free(sm);
 }
-
-void test_submodule_modify__save_last(void)
-{
-	git_submodule *sm;
-
-	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_gitmodules_only"));
-	cl_git_pass(git_submodule_save(sm));
-	git_submodule_free(sm);
-}