[vala/staging] vala: Fix circular reference in EnumValueType

[Rico Tzschichholz <ricotz src gnome org>]

commit b592c3dbb7b64c18446f61d5df87d1489f44aba9
Author: Princeton Ferro <princetonferro gmail com>
Date:   Sun Mar 1 09:54:13 2020 +0100

    vala: Fix circular reference in EnumValueType

 vala/valaenumvaluetype.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/vala/valaenumvaluetype.vala b/vala/valaenumvaluetype.vala
index 6c6aca398..027c30db1 100644
--- a/vala/valaenumvaluetype.vala
+++ b/vala/valaenumvaluetype.vala
@@ -50,7 +50,7 @@ public class Vala.EnumValueType : ValueType {
                        to_string_method.is_extern = true;
                        to_string_method.set_attribute_string ("CCode", "cheader_filename", "glib-object.h");
                        to_string_method.owner = type_symbol.scope;
-                       to_string_method.this_parameter = new Parameter ("this", this);
+                       to_string_method.this_parameter = new Parameter ("this", copy ());
                        to_string_method.scope.add (to_string_method.this_parameter.name, 
to_string_method.this_parameter);
                }
                return to_string_method;