[gjs] Fix strict aliasing errors. (Type-punned pointer warnings.)

[C. Scott Ananian <cananian src gnome org>]

commit 64cb8f2dfe00004433b210e5ba0d8c9e0e95775a
Author: C. Scott Ananian <cscott litl com>
Date:   Wed Jun 3 18:29:29 2009 -0400

    Fix strict aliasing errors. (Type-punned pointer warnings.)
    
    http://bugzilla.gnome.org/show_bug.cgi?id=584849
---
 gjsdbus/dbus-signals.c |   19 ++++++++++++++-----
 gjsdbus/dbus.c         |    9 ++++++---
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/gjsdbus/dbus-signals.c b/gjsdbus/dbus-signals.c
index cbe2e15..bdb58bc 100644
--- a/gjsdbus/dbus-signals.c
+++ b/gjsdbus/dbus-signals.c
@@ -162,10 +162,15 @@ signal_watcher_table_add(GHashTable      **table_p,
                                          g_free,
                                          signal_watcher_list_free);
     } else {
-        if (!g_hash_table_lookup_extended(*table_p,
+        gpointer k, v;
+        if (g_hash_table_lookup_extended(*table_p,
                                           key,
-                                          (gpointer*)&original_key,
-                                          (gpointer*)&list)) {
+                                          &k, &v)) {
+            // do this assignment as separate step so as to avoid
+            // passing a type-punned pointer into g_hash_table_lookup_extended
+            original_key = (char *) k;
+            list = (GSList *) v;
+        } else {
             original_key = g_strdup(key);
             list = NULL;
         }
@@ -186,16 +191,20 @@ signal_watcher_table_remove(GHashTable       *table,
     GSList *list;
     GSList *l;
     char *original_key;
+    gpointer k, v;
 
     if (table == NULL)
         return; /* Never lazily-created the table, nothing ever added */
 
     if (!g_hash_table_lookup_extended(table,
                                       key,
-                                      (gpointer*)&original_key,
-                                      (gpointer*)&list)) {
+                                      &k, &v)) {
         return;
     }
+    // do this assignment as separate step so as to avoid
+    // passing a type-punned pointer into g_hash_table_lookup_extended
+    original_key = (char *) k;
+    list = (GSList *) v;
 
     l = g_slist_find(list, watcher);
     if (!l)
diff --git a/gjsdbus/dbus.c b/gjsdbus/dbus.c
index 0651f22..43bf0ad 100644
--- a/gjsdbus/dbus.c
+++ b/gjsdbus/dbus.c
@@ -1608,7 +1608,10 @@ gjs_dbus_unregister_json(DBusConnection *connection,
 
 typedef struct {
     DBusConnection *connection;
-    GObject *gobj;
+    /* strict aliasing rules require us to relate the 'gobj' field to a
+     * void * type here, in order to be able to pass it to
+     * g_object_*_weak_pointer (which takes a void **) */
+    union { GObject *gobj; void *weak_ptr; };
     char *iface_name;
 } GjsDBusGObject;
 
@@ -1621,7 +1624,7 @@ gobj_path_unregistered(DBusConnection  *connection,
     g = user_data;
 
     if (g->gobj) {
-        g_object_remove_weak_pointer(g->gobj, (void**) &g->gobj);
+        g_object_remove_weak_pointer(g->gobj, &g->weak_ptr /* aka, gobj */);
         g->gobj = NULL;
     }
 
@@ -1802,7 +1805,7 @@ gjs_dbus_register_g_object(DBusConnection *connection,
         g_warning("Failed to register object path %s", path);
     }
 
-    g_object_add_weak_pointer(g->gobj, (void**) &g->gobj);
+    g_object_add_weak_pointer(g->gobj, &g->weak_ptr /* aka, gobj */);
 }
 
 void