[pygobject] GVariant: Don't use pyg_boxed_new as GVariant isn't a PyGBoxed but a PyGIStruct.

[Christoph Reiter <creiter src gnome org>]

commit 49880800b35029de3731523eede1b3174f10c1db
Author: Christoph Reiter <creiter src gnome org>
Date:   Sat Jul 4 21:40:04 2015 +0200

    GVariant: Don't use pyg_boxed_new as GVariant isn't a PyGBoxed but a PyGIStruct.
    
    This only worked because they share the same struct layout.
    This adds a new constructor for creating a new PyGIStruct instance from GType.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=751956

 gi/pygi-struct.c |   32 ++++++++++++++++++++++++++++++++
 gi/pygi-struct.h |    5 +++++
 gi/pygi-value.c  |    3 ++-
 3 files changed, 39 insertions(+), 1 deletions(-)
---
diff --git a/gi/pygi-struct.c b/gi/pygi-struct.c
index d84eed5..c379a88 100644
--- a/gi/pygi-struct.c
+++ b/gi/pygi-struct.c
@@ -132,6 +132,38 @@ _struct_init (PyObject *self,
 
 PYGLIB_DEFINE_TYPE("gi.Struct", PyGIStruct_Type, PyGIStruct);
 
+
+PyObject *
+_pygi_struct_new_from_g_type (GType g_type,
+                              gpointer      pointer,
+                              gboolean      free_on_dealloc)
+{
+    PyGIStruct *self;
+    PyTypeObject *type;
+
+    type = (PyTypeObject *)pygi_type_import_by_g_type (g_type);
+
+    if (!type)
+        type = (PyTypeObject *)&PyGIStruct_Type; /* fallback */
+
+    if (!PyType_IsSubtype (type, &PyGIStruct_Type)) {
+        PyErr_SetString (PyExc_TypeError, "must be a subtype of gi.Struct");
+        return NULL;
+    }
+
+    self = (PyGIStruct *) type->tp_alloc (type, 0);
+    if (self == NULL) {
+        return NULL;
+    }
+
+    pyg_pointer_set_ptr (self, pointer);
+    ( (PyGPointer *) self)->gtype = g_type;
+    self->free_on_dealloc = free_on_dealloc;
+
+    return (PyObject *) self;
+}
+
+
 PyObject *
 _pygi_struct_new (PyTypeObject *type,
                   gpointer      pointer,
diff --git a/gi/pygi-struct.h b/gi/pygi-struct.h
index ab303e0..347c55f 100644
--- a/gi/pygi-struct.h
+++ b/gi/pygi-struct.h
@@ -31,6 +31,11 @@ _pygi_struct_new (PyTypeObject *type,
                   gpointer      pointer,
                   gboolean      free_on_dealloc);
 
+PyObject *
+_pygi_struct_new_from_g_type (GType g_type,
+                              gpointer      pointer,
+                              gboolean      free_on_dealloc);
+
 void _pygi_struct_register_types (PyObject *m);
 
 G_END_DECLS
diff --git a/gi/pygi-value.c b/gi/pygi-value.c
index 3bdd854..413e14a 100644
--- a/gi/pygi-value.c
+++ b/gi/pygi-value.c
@@ -18,6 +18,7 @@
 
 #include <Python.h>
 #include "pygi-value.h"
+#include "pygi-struct.h"
 #include "pyglib-python-compat.h"
 #include "pygobject-private.h"
 #include "pygtype.h"
@@ -810,7 +811,7 @@ pygi_value_to_py_structured_type (const GValue *value, GType fundamental, gboole
             Py_INCREF(Py_None);
             return Py_None;
         }
-        return pyg_boxed_new(G_TYPE_VARIANT, g_variant_ref(v), FALSE, FALSE);
+        return _pygi_struct_new_from_g_type (G_TYPE_VARIANT, g_variant_ref(v), FALSE);
     }
     default:
     {