fixes #837

tests/objects/tobject3.nim

@@ -1,5 +1,9 @@
+
+# It turned out that it's hard to generate correct for these two test cases at
+# the same time.
+
 type
-  TFoo = ref object of TObject
+  TFoo = ref object of RootObj
     Data: int  
   TBar = ref object of TFoo
     nil
@@ -26,3 +30,30 @@ var b: TBar2
 new(b)
 
 Foo(b)
+
+# bug #837
+type
+  PView* = ref TView
+  TView* {.inheritable.} = object
+    data: int
+
+  PWindow* = ref TWindow
+  TWindow* = object of TView
+    data3: int
+
+  PDesktop* = ref TDesktop
+  TDesktop* = object of TView
+    data2: int
+
+proc makeDesktop(): PDesktop = new(TDesktop)
+
+proc makeWindow(): PWindow = new(TWindow)
+
+proc thisCausesError(a: var PView, b: PView) =
+  discard
+
+var dd = makeDesktop()
+var aa = makeWindow()
+
+thisCausesError(dd, aa)
+