[Go] Fix member variables in base classes to handle CWRAP_NATURAL_VAR

correctly.  Add a test case for the problem.

Fixes #339.

Examples/test-suite/common.mk

@@ -246,6 +246,7 @@ CPP_TEST_CASES += \
 	ignore_parameter \
 	import_nomodule \
 	inherit \
+	inherit_member \
 	inherit_missing \
 	inherit_same_name \
 	inherit_target_language \

Examples/test-suite/go/inherit_member_runme.go

@@ -0,0 +1,15 @@
+package main
+
+import wrap "./inherit_member"
+
+func main() {
+	s := wrap.NewChild()
+	s.SetPvar("p")
+	s.SetCvar("c")
+	if s.GetPvar() != "p" {
+		panic(s.GetPvar())
+	}
+	if s.GetCvar() != "c" {
+		panic(s.GetCvar())
+	}
+}

Examples/test-suite/inherit_member.i

@@ -0,0 +1,17 @@
+// Based on https://github.com/swig/swig/issues/339 .
+
+%module inherit_member
+
+%include <std_string.i>
+
+%inline %{
+
+struct parent {
+  std::string pvar;
+};
+
+ struct child : public parent {
+  std::string cvar;
+};
+
+%}

Source/Modules/go.cxx

@@ -3160,15 +3160,26 @@ private:
     Setattr(var, "type", var_type);
 
     SwigType *vt = Copy(var_type);
-    if (SwigType_isclass(vt)) {
-      SwigType_add_pointer(vt);
-    }
 
     int flags = Extend | SmartPointer | use_naturalvar_mode(var);
     if (isNonVirtualProtectedAccess(var)) {
       flags |= CWRAP_ALL_PROTECTED_ACCESS;
     }
 
+    // Copied from Swig_wrapped_member_var_type.
+    if (SwigType_isclass(vt)) {
+      if (flags & CWRAP_NATURAL_VAR) {
+	if (CPlusPlus) {
+	  if (!SwigType_isconst(vt)) {
+	    SwigType_add_qualifier(vt, "const");
+	  }
+	  SwigType_add_reference(vt);
+	}
+      } else {
+	SwigType_add_pointer(vt);
+      }
+    }
+
     String *mname = Swig_name_member(getNSpace(), Getattr(var_class, "sym:name"), var_name);
 
     if (is_assignable(var)) {