[vala/0.46] vala: Fix circular reference in EnumValueType

[Rico Tzschichholz <ricotz src gnome org>]

commit 2754d46fbd47ad45c85a707a16f6c389e3b04f98
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 be8ac15d0..9152b90e8 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;