[glib: 1/3] Fix compiler warning about uninitialized variable in giomodule

[Sebastian Dröge <sdroege src gnome org>]

commit b4a5157f9586ef7bc808cc4da5abfd33d20b0883
Author: Sebastian Dröge <sebastian centricular com>
Date:   Thu Jan 24 16:35:13 2019 +0200

    Fix compiler warning about uninitialized variable in giomodule
    
    It could've never been uninitialized in this code but the code flow is
    not obvious to the compiler. Initialize it to NULL and for clarity also
    add an assertion that it is not NULL anymore on usage.
    
    In file included from ../glib/glib.h:62,
                     from ../gobject/gbinding.h:28,
                     from ../glib/glib-object.h:23,
                     from ../gio/gioenums.h:28,
                     from ../gio/giotypes.h:28,
                     from ../gio/giomodule.h:28,
                     from ../gio/giomodule.c:25:
    ../gio/giomodule.c: In function ‘_g_io_module_get_default’:
    ../glib/gmessages.h:343:25: warning: ‘extension’ may be used uninitialized in this function 
[-Wmaybe-uninitialized]
     #define g_debug(...)    g_log (G_LOG_DOMAIN,         \
                             ^~~~~
    ../gio/giomodule.c:912:17: note: ‘extension’ was declared here
       GIOExtension *extension, *preferred;
                     ^~~~~~~~~

 gio/giomodule.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/gio/giomodule.c b/gio/giomodule.c
index 52c60c210..b92162dcc 100644
--- a/gio/giomodule.c
+++ b/gio/giomodule.c
@@ -909,7 +909,7 @@ _g_io_module_get_default (const gchar         *extension_point,
   const char *use_this;
   GList *l;
   GIOExtensionPoint *ep;
-  GIOExtension *extension, *preferred;
+  GIOExtension *extension = NULL, *preferred;
   gpointer impl;
 
   g_rec_mutex_lock (&default_modules_lock);
@@ -986,9 +986,12 @@ _g_io_module_get_default (const gchar         *extension_point,
   g_rec_mutex_unlock (&default_modules_lock);
 
   if (impl != NULL)
-    g_debug ("%s: Found default implementation %s (%s) for ‘%s’",
-             G_STRFUNC, g_io_extension_get_name (extension),
-             G_OBJECT_TYPE_NAME (impl), extension_point);
+    {
+      g_assert (extension != NULL);
+      g_debug ("%s: Found default implementation %s (%s) for ‘%s’",
+               G_STRFUNC, g_io_extension_get_name (extension),
+               G_OBJECT_TYPE_NAME (impl), extension_point);
+    }
   else
     g_debug ("%s: Failed to find default implementation for ‘%s’",
              G_STRFUNC, extension_point);