gatomic: Add various casts to use of g_atomic_*()s to fix warnings

When compiling GLib with `-Wsign-conversion`, we get various warnings
about the atomic calls. A lot of these were fixed by
3ad375a629c91a27d0165a31f0ed298fd553de0a, but some remain. Fix them by
adding appropriate casts at the call sites.

Note that `g_atomic_int_{and,or,xor}()` actually all operate on `guint`s
rather than `gint`s (which is what the rest of the `g_atomic_int_*()`
functions operate on). I can’t find any written reasoning for this, but
assume that it’s because signedness is irrelevant when you’re using an
integer as a bit field. It’s unfortunate that they’re named a
`g_atomic_int_*()` rather than `g_atomic_uint_*()` functions.

Tested by compiling GLib as:
```
CFLAGS=-Wsign-conversion jhbuild make -ac |& grep atomic
```

I’m not going to add `-Wsign-conversion` to the set of default warnings
for building GLib, because it mostly produces false positives throughout
the rest of GLib.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Fixes: #1565

1 files changed, 4 insertions, 4 deletions

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index f1f0921d4..3411033f3 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -3148,7 +3148,7 @@ g_dbus_connection_add_filter (GDBusConnection            *connection,
 
   CONNECTION_LOCK (connection);
   data = g_new0 (FilterData, 1);
-  data->id = g_atomic_int_add (&_global_filter_id, 1); /* TODO: overflow etc. */
+  data->id = (guint) g_atomic_int_add (&_global_filter_id, 1); /* TODO: overflow etc. */
   data->ref_count = 1;
   data->filter_function = filter_function;
   data->user_data = user_data;
@@ -3508,7 +3508,7 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
   subscriber.callback = callback;
   subscriber.user_data = user_data;
   subscriber.user_data_free_func = user_data_free_func;
-  subscriber.id = g_atomic_int_add (&_global_subscriber_id, 1); /* TODO: overflow etc. */
+  subscriber.id = (guint) g_atomic_int_add (&_global_subscriber_id, 1); /* TODO: overflow etc. */
   subscriber.context = g_main_context_ref_thread_default ();
 
   /* see if we've already have this rule */
@@ -5198,7 +5198,7 @@ g_dbus_connection_register_object (GDBusConnection             *connection,
     }
 
   ei = g_new0 (ExportedInterface, 1);
-  ei->id = g_atomic_int_add (&_global_registration_id, 1); /* TODO: overflow etc. */
+  ei->id = (guint) g_atomic_int_add (&_global_registration_id, 1); /* TODO: overflow etc. */
   ei->eo = eo;
   ei->user_data = user_data;
   ei->user_data_free_func = user_data_free_func;
@@ -6858,7 +6858,7 @@ g_dbus_connection_register_subtree (GDBusConnection           *connection,
 
   es->vtable = _g_dbus_subtree_vtable_copy (vtable);
   es->flags = flags;
-  es->id = g_atomic_int_add (&_global_subtree_registration_id, 1); /* TODO: overflow etc. */
+  es->id = (guint) g_atomic_int_add (&_global_subtree_registration_id, 1); /* TODO: overflow etc. */
   es->user_data = user_data;
   es->user_data_free_func = user_data_free_func;
   es->context = g_main_context_ref_thread_default ();