[libpeas] Warn if creating an extension fails

[Steve Frécinaux <sfre src gnome org>]

commit 63153f709e4ed60a6e895ac00f6631094f1ae97b
Author: Garrett Regier <alias301 gmail com>
Date:   Fri Mar 4 22:47:19 2011 -0800

    Warn if creating an extension fails

 libpeas/peas-engine.c                      |   15 +++++++++++++--
 libpeas/peas-extension-set.c               |    6 ++++--
 loaders/python/peas-plugin-loader-python.c |    3 +--
 tests/libpeas/testing/testing-extension.c  |   14 +++++++++-----
 4 files changed, 27 insertions(+), 11 deletions(-)
---
diff --git a/libpeas/peas-engine.c b/libpeas/peas-engine.c
index be848fb..93b99c6 100644
--- a/libpeas/peas-engine.c
+++ b/libpeas/peas-engine.c
@@ -979,6 +979,7 @@ peas_engine_create_extensionv (PeasEngine     *engine,
                                GParameter     *parameters)
 {
   PeasPluginLoader *loader;
+  PeasExtension *extension;
 
   g_return_val_if_fail (PEAS_IS_ENGINE (engine), NULL);
   g_return_val_if_fail (info != NULL, NULL);
@@ -986,8 +987,18 @@ peas_engine_create_extensionv (PeasEngine     *engine,
   g_return_val_if_fail (G_TYPE_IS_INTERFACE (extension_type), FALSE);
 
   loader = get_plugin_loader (engine, info);
-  return peas_plugin_loader_create_extension (loader, info, extension_type,
-                                              n_parameters, parameters);
+  extension = peas_plugin_loader_create_extension (loader, info, extension_type,
+                                                   n_parameters, parameters);
+
+  if (!PEAS_IS_EXTENSION (extension))
+    {
+      g_warning ("Plugin '%s' does not provide a '%s' extension",
+                 peas_plugin_info_get_module_name (info),
+                 g_type_name (extension_type));
+      return NULL;
+    }
+
+  return extension;
 }
 
 /**
diff --git a/libpeas/peas-extension-set.c b/libpeas/peas-extension-set.c
index 8f4b75b..6dd9018 100644
--- a/libpeas/peas-extension-set.c
+++ b/libpeas/peas-extension-set.c
@@ -198,12 +198,14 @@ add_extension (PeasExtensionSet *set,
   if (!peas_plugin_info_is_loaded (info))
     return;
 
+  if (!peas_engine_provides_extension (set->priv->engine, info,
+                                       set->priv->exten_type))
+    return;
+
   exten = peas_engine_create_extensionv (set->priv->engine, info,
                                          set->priv->exten_type,
                                          set->priv->n_parameters,
                                          set->priv->parameters);
-  if (!exten)
-    return;
 
 /*  peas_plugin_info_ref (info); */
 
diff --git a/loaders/python/peas-plugin-loader-python.c b/loaders/python/peas-plugin-loader-python.c
index 95de6b9..ddfa949 100644
--- a/loaders/python/peas-plugin-loader-python.c
+++ b/loaders/python/peas-plugin-loader-python.c
@@ -106,8 +106,7 @@ find_python_extension_type (PeasPluginInfo *info,
     }
 
   Py_DECREF (pygtype);
-  g_debug ("No '%s' derivative found in Python plugin '%s'",
-           g_type_name (exten_type), peas_plugin_info_get_name (info));
+
   return NULL;
 }
 
diff --git a/tests/libpeas/testing/testing-extension.c b/tests/libpeas/testing/testing-extension.c
index 0b6ca14..5ae51a3 100644
--- a/tests/libpeas/testing/testing-extension.c
+++ b/tests/libpeas/testing/testing-extension.c
@@ -156,7 +156,6 @@ void
 testing_extension_create_invalid_ (PeasEngine *engine)
 {
   PeasPluginInfo *info;
-  PeasExtension *extension;
 
   info = peas_engine_get_plugin_info (engine, extension_plugin);
 
@@ -193,10 +192,15 @@ testing_extension_create_invalid_ (PeasEngine *engine)
 
 
   /* Does not implement this GType */
-  extension = peas_engine_create_extension (engine, info,
-                                            INTROSPECTION_TYPE_UNIMPLEMENTED,
-                                            NULL);
-  g_assert (!PEAS_IS_EXTENSION (extension));
+  if (g_test_trap_fork (0, G_TEST_TRAP_SILENCE_STDOUT | G_TEST_TRAP_SILENCE_STDERR))
+    {
+      peas_engine_create_extension (engine, info,
+                                    INTROSPECTION_TYPE_UNIMPLEMENTED,
+                                    NULL);
+      exit (0);
+    }
+  g_test_trap_assert_failed ();
+  g_test_trap_assert_stderr ("*WARNING*");
 }
 
 void