[pygobject] Fix leaked vfunc return values

[Simon Feltman <sfeltman src gnome org>]

commit 91e4cb2063d4e83fb1f6586a4396471d64f234f4
Author: Simon Feltman <s feltman gmail com>
Date:   Mon Oct 15 04:03:50 2012 -0700

    Fix leaked vfunc return values
    
    Simple fix to dec ref returned values from closures wrapping
    python functions.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=686140

 gi/pygi-closure.c |    1 +
 tests/test_gi.py  |   21 +++++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)
---
diff --git a/gi/pygi-closure.c b/gi/pygi-closure.c
index 8ba8020..0e49c72 100644
--- a/gi/pygi-closure.c
+++ b/gi/pygi-closure.c
@@ -506,6 +506,7 @@ _pygi_closure_handle (ffi_cif *cif,
     }
 
     _pygi_closure_set_out_arguments (closure->info, retval, out_args, result);
+    Py_DECREF (retval);
 
 end:
     g_free (out_args);
diff --git a/tests/test_gi.py b/tests/test_gi.py
index 4301d03..51cb6f9 100644
--- a/tests/test_gi.py
+++ b/tests/test_gi.py
@@ -10,6 +10,7 @@ import shutil
 import os
 import locale
 import subprocess
+import gc
 from io import StringIO, BytesIO
 
 import gi
@@ -1623,6 +1624,8 @@ class TestGObject(unittest.TestCase):
 class TestPythonGObject(unittest.TestCase):
 
     class Object(GIMarshallingTests.Object):
+        return_for_caller_allocated_out_parameter = 'test caller alloc return'
+
         def __init__(self, int):
             GIMarshallingTests.Object.__init__(self)
             self.val = None
@@ -1657,7 +1660,7 @@ class TestPythonGObject(unittest.TestCase):
             return (5, 42, 99)
 
         def do_vfunc_caller_allocated_out_parameter(self):
-            return 'hello'
+            return self.return_for_caller_allocated_out_parameter
 
     class SubObject(GIMarshallingTests.SubObject):
         def __init__(self, int):
@@ -1705,7 +1708,8 @@ class TestPythonGObject(unittest.TestCase):
         self.assertEqual(object_.vfunc_return_value_and_one_out_parameter(), (5, 42))
         self.assertEqual(object_.vfunc_return_value_and_multiple_out_parameters(), (5, 42, 99))
 
-        self.assertEqual(object_.vfunc_caller_allocated_out_parameter(), 'hello')
+        self.assertEqual(object_.vfunc_caller_allocated_out_parameter(),
+                         object_.return_for_caller_allocated_out_parameter)
 
         class ObjectWithoutVFunc(GIMarshallingTests.Object):
             def __init__(self, int):
@@ -1715,6 +1719,19 @@ class TestPythonGObject(unittest.TestCase):
         object_.method_with_default_implementation(84)
         self.assertEqual(object_.props.int, 84)
 
+    def test_vfunc_return_ref_count(self):
+        obj = self.Object(int=42)
+        ref_count = sys.getrefcount(obj.return_for_caller_allocated_out_parameter)
+        ret = obj.vfunc_caller_allocated_out_parameter()
+        gc.collect()
+
+        # Make sure the return and what the vfunc returned
+        # are equal but not the same object.
+        self.assertEqual(ret, obj.return_for_caller_allocated_out_parameter)
+        self.assertFalse(ret is obj.return_for_caller_allocated_out_parameter)
+        self.assertEqual(sys.getrefcount(obj.return_for_caller_allocated_out_parameter),
+                         ref_count)
+
     def test_subobject_parent_vfunc(self):
         object_ = self.SubObject(int=81)
         object_.method_with_default_implementation(87)