add error when passing a struct/class by value + derivation

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@6368 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Examples/test-suite/struct_value.i

@@ -3,7 +3,13 @@
 %inline %{
 
 struct Foo {
-   int x;
+  int x;
+
+  // this works
+  int rmethod(const Foo& f) { return f.x; }
+
+  // this doesn't when DerFoo (below) is introduced
+  int method(Foo f) { return f.x; }
 };
 
 struct Bar {
@@ -11,4 +17,25 @@ struct Bar {
    struct Foo b;
 };
 
+/*
+  When the next derived class is declared, the 
+  following bad method is generated
+
+  static void *_DerFooTo_Foo(void *x) {   // **** bad ****
+    return (void *)((Foo)  ((DerFoo) x));
+  }
+
+  static void *_p_DerFooTo_p_Foo(void *x) {   // *** good ***
+    return (void *)((Foo *)  ((DerFoo *) x));
+  }
+  
+  if the derived class is deleted, it works again 
+
+  if the previos Foo::method
+
+ */
+struct DerFoo : Foo {
+};
+
+#
 %}