all: fix deprecated function declaration without a prototype

Clang 15 now (correctly) warns about this:

  ../src/libnm-core-impl/nm-vpn-plugin-info.c:201:40: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
  _nm_vpn_plugin_info_get_default_dir_etc()
                                         ^
                                          void
  ../src/libnm-core-impl/nm-vpn-plugin-info.c:213:40: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
  _nm_vpn_plugin_info_get_default_dir_lib()
                                         ^
                                          void
  ../src/libnm-core-impl/nm-vpn-plugin-info.c:226:41: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
  _nm_vpn_plugin_info_get_default_dir_user()
                                          ^
                                           void
  ../src/libnm-core-impl/nm-vpn-plugin-info.c:315:29: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
  nm_vpn_plugin_info_list_load()
                              ^
                               void

6 files changed, 11 insertions, 11 deletions

diff --git a/src/core/NetworkManagerUtils.c b/src/core/NetworkManagerUtils.c
index 32c1fd17b6..9a1bb72966 100644
--- a/src/core/NetworkManagerUtils.c
+++ b/src/core/NetworkManagerUtils.c
@@ -1834,7 +1834,7 @@ nm_platform_setup(NMPlatform *instance)
  * Returns: (transfer none): The #NMPlatform singleton reference.
  */
 NMPlatform *
-nm_platform_get()
+nm_platform_get(void)
 {
     g_assert(singleton_instance);
 
diff --git a/src/core/main-utils.c b/src/core/main-utils.c
index 444e122e8a..aec73e12db 100644
--- a/src/core/main-utils.c
+++ b/src/core/main-utils.c
@@ -103,7 +103,7 @@ nm_main_utils_write_pidfile(const char *pidfile)
 }
 
 void
-nm_main_utils_ensure_statedir()
+nm_main_utils_ensure_statedir(void)
 {
     gs_free char *parent = NULL;
     int           errsv;
@@ -129,7 +129,7 @@ nm_main_utils_ensure_statedir()
 }
 
 void
-nm_main_utils_ensure_rundir()
+nm_main_utils_ensure_rundir(void)
 {
     int errsv;
 
diff --git a/src/core/nm-auth-manager.c b/src/core/nm-auth-manager.c
index 0f7e0c0dd8..242f005543 100644
--- a/src/core/nm-auth-manager.c
+++ b/src/core/nm-auth-manager.c
@@ -524,7 +524,7 @@ _name_owner_get_cb(const char *name_owner, GError *error, gpointer user_data)
 /*****************************************************************************/
 
 NMAuthManager *
-nm_auth_manager_get()
+nm_auth_manager_get(void)
 {
     g_return_val_if_fail(singleton_instance, NULL);
 
diff --git a/src/core/nm-config.c b/src/core/nm-config.c
index 3d23d4f6cd..db8f08bf09 100644
--- a/src/core/nm-config.c
+++ b/src/core/nm-config.c
@@ -680,7 +680,7 @@ nm_config_cmd_line_options_add_to_entries(NMConfigCmdLineOptions *cli, GOptionCo
 /*****************************************************************************/
 
 GKeyFile *
-nm_config_create_keyfile()
+nm_config_create_keyfile(void)
 {
     GKeyFile *keyfile;
 
diff --git a/src/core/nm-core-utils.c b/src/core/nm-core-utils.c
index 3d6790759d..6ee39c95f1 100644
--- a/src/core/nm-core-utils.c
+++ b/src/core/nm-core-utils.c
@@ -58,7 +58,7 @@ G_STATIC_ASSERT(sizeof(NMUtilsTestFlags) <= sizeof(int));
 static int _nm_utils_testing = 0;
 
 gboolean
-nm_utils_get_testing_initialized()
+nm_utils_get_testing_initialized(void)
 {
     NMUtilsTestFlags flags;
 
@@ -69,7 +69,7 @@ nm_utils_get_testing_initialized()
 }
 
 NMUtilsTestFlags
-nm_utils_get_testing()
+nm_utils_get_testing(void)
 {
     NMUtilsTestFlags flags;
 
diff --git a/src/libnm-core-impl/nm-vpn-plugin-info.c b/src/libnm-core-impl/nm-vpn-plugin-info.c
index a6096563ba..4f9129365a 100644
--- a/src/libnm-core-impl/nm-vpn-plugin-info.c
+++ b/src/libnm-core-impl/nm-vpn-plugin-info.c
@@ -198,7 +198,7 @@ _sort_files(LoadDirInfo *a, LoadDirInfo *b)
  *   VPN plugin directory.
  */
 const char *
-_nm_vpn_plugin_info_get_default_dir_etc()
+_nm_vpn_plugin_info_get_default_dir_etc(void)
 {
     return DEFAULT_DIR_ETC;
 }
@@ -210,7 +210,7 @@ _nm_vpn_plugin_info_get_default_dir_etc()
  *   VPN plugin directory.
  */
 const char *
-_nm_vpn_plugin_info_get_default_dir_lib()
+_nm_vpn_plugin_info_get_default_dir_lib(void)
 {
     return DEFAULT_DIR_LIB;
 }
@@ -223,7 +223,7 @@ _nm_vpn_plugin_info_get_default_dir_lib()
  * that directory.
  */
 const char *
-_nm_vpn_plugin_info_get_default_dir_user()
+_nm_vpn_plugin_info_get_default_dir_user(void)
 {
     return nm_str_not_empty(g_getenv("NM_VPN_PLUGIN_DIR"));
 }
@@ -312,7 +312,7 @@ _nm_vpn_plugin_info_list_load_dir(const char               *dirname,
  * Since: 1.2
  */
 GSList *
-nm_vpn_plugin_info_list_load()
+nm_vpn_plugin_info_list_load(void)
 {
     int               i;
     gint64            uid;