all: fix -Wcast-function-type warnings

GCC 8.0's -Wcast-function-type objects casting function pointers to ones
with incompatible prototypes. Sometimes we do that on purpose though.

Notably, the g_source_set_callback()'s func argument can point to functions
of various prototypes. Also, libnm-glib/nm-remote-connection is perhaps
just not worth reworking, that would just be a waste of time.

A cast to void(*)(void) avoids the GCC warning, let's use it.

(cherry picked from commit ee916a1e9ec3f06f8c88dc3d95058a6bd1561c7d)
(cherry picked from commit 42913505a3c62dac199708f3da338fa97f87d58e)

3 files changed, 9 insertions, 9 deletions

diff --git a/clients/tui/newt/nmt-newt-form.c b/clients/tui/newt/nmt-newt-form.c
index 835c1aba7d..ccf447eada 100644
--- a/clients/tui/newt/nmt-newt-form.c
+++ b/clients/tui/newt/nmt-newt-form.c
@@ -360,7 +360,7 @@ nmt_newt_form_real_show (NmtNewtForm *form)
 		keypress_source = g_io_create_watch (io, G_IO_IN);
 		g_source_set_can_recurse (keypress_source, TRUE);
 		g_source_set_callback (keypress_source,
-		                       (GSourceFunc) nmt_newt_form_keypress_callback,
+		                       (GSourceFunc)(void (*) (void)) nmt_newt_form_keypress_callback,
 		                       NULL, NULL);
 		g_source_attach (keypress_source, NULL);
 		g_io_channel_unref (io);
diff --git a/libnm-glib/nm-remote-connection.c b/libnm-glib/nm-remote-connection.c
index 6dcce0ba97..820f9e5ca5 100644
--- a/libnm-glib/nm-remote-connection.c
+++ b/libnm-glib/nm-remote-connection.c
@@ -218,7 +218,7 @@ proxy_destroy_cb (DBusGProxy* proxy, gpointer user_data) {
 static void
 result_cb (RemoteCall *call, DBusGProxyCall *proxy_call, GError *error)
 {
-	NMRemoteConnectionResultFunc func = (NMRemoteConnectionResultFunc) call->callback;
+	NMRemoteConnectionResultFunc func = (NMRemoteConnectionResultFunc)(void (*) (void)) call->callback;
 	GError *local_error = NULL;
 
 	if (!error) {
@@ -254,7 +254,7 @@ nm_remote_connection_commit_changes (NMRemoteConnection *self,
 
 	priv = NM_REMOTE_CONNECTION_GET_PRIVATE (self);
 
-	call = remote_call_new (self, result_cb, (GFunc) callback, user_data);
+	call = remote_call_new (self, result_cb, (GFunc)(void (*) (void)) callback, user_data);
 	if (!call)
 		return;
 
@@ -294,7 +294,7 @@ nm_remote_connection_commit_changes_unsaved (NMRemoteConnection *connection,
 
 	priv = NM_REMOTE_CONNECTION_GET_PRIVATE (connection);
 
-	call = remote_call_new (connection, result_cb, (GFunc) callback, user_data);
+	call = remote_call_new (connection, result_cb, (GFunc)(void (*) (void)) callback, user_data);
 	if (!call)
 		return;
 
@@ -331,7 +331,7 @@ nm_remote_connection_save (NMRemoteConnection *connection,
 
 	priv = NM_REMOTE_CONNECTION_GET_PRIVATE (connection);
 
-	call = remote_call_new (connection, result_cb, (GFunc) callback, user_data);
+	call = remote_call_new (connection, result_cb, (GFunc)(void (*) (void)) callback, user_data);
 	if (!call)
 		return;
 
@@ -359,7 +359,7 @@ nm_remote_connection_delete (NMRemoteConnection *self,
 
 	priv = NM_REMOTE_CONNECTION_GET_PRIVATE (self);
 
-	call = remote_call_new (self, result_cb, (GFunc) callback, user_data);
+	call = remote_call_new (self, result_cb, (GFunc)(void (*) (void)) callback, user_data);
 	if (!call)
 		return;
 
@@ -372,7 +372,7 @@ nm_remote_connection_delete (NMRemoteConnection *self,
 static void
 get_secrets_cb (RemoteCall *call, DBusGProxyCall *proxy_call, GError *error)
 {
-	NMRemoteConnectionGetSecretsFunc func = (NMRemoteConnectionGetSecretsFunc) call->callback;
+	NMRemoteConnectionGetSecretsFunc func = (NMRemoteConnectionGetSecretsFunc)(void (*) (void)) call->callback;
 	GHashTable *secrets = NULL;
 	GError *local_error = NULL;
 
@@ -415,7 +415,7 @@ nm_remote_connection_get_secrets (NMRemoteConnection *self,
 
 	priv = NM_REMOTE_CONNECTION_GET_PRIVATE (self);
 
-	call = remote_call_new (self, get_secrets_cb, (GFunc) callback, user_data);
+	call = remote_call_new (self, get_secrets_cb, (GFunc)(void (*) (void)) callback, user_data);
 	if (!call)
 		return;
 
diff --git a/shared/nm-utils/nm-udev-utils.c b/shared/nm-utils/nm-udev-utils.c
index 79d4426de9..709f759043 100644
--- a/shared/nm-utils/nm-udev-utils.c
+++ b/shared/nm-utils/nm-udev-utils.c
@@ -257,7 +257,7 @@ nm_udev_client_new (const char *const*subsystems,
 				channel = g_io_channel_unix_new (udev_monitor_get_fd (self->monitor));
 				self->watch_source = g_io_create_watch (channel, G_IO_IN);
 				g_io_channel_unref (channel);
-				g_source_set_callback (self->watch_source, (GSourceFunc) monitor_event, self, NULL);
+				g_source_set_callback (self->watch_source, (GSourceFunc)(void (*) (void)) monitor_event, self, NULL);
 				g_source_attach (self->watch_source, g_main_context_get_thread_default ());
 				g_source_unref (self->watch_source);
 			}