introduce class_typet::static_members

This enables tracking static fields of a class, following the same pattern
as used for methods.

Author: Daniel Kroening

src/util/irep_ids.def

@@ -400,6 +400,7 @@ IREP_ID_ONE(member_initializers)
 IREP_ID_ONE(member_initializer)
 IREP_ID_ONE(method_qualifier)
 IREP_ID_ONE(methods)
+IREP_ID_ONE(static_members)
 IREP_ID_ONE(constructor)
 IREP_ID_ONE(destructor)
 IREP_ID_ONE(bases)

src/util/std_types.h

@@ -330,6 +330,19 @@ class class_typet:public struct_typet
     return (methodst &)(add(ID_methods).get_sub());
   }
 
+  using static_membert = componentt;
+  using static_memberst = componentst;
+
+  const static_memberst &static_members() const
+  {
+    return (const static_memberst &)(find(ID_static_members).get_sub());
+  }
+
+  static_memberst &static_members()
+  {
+    return (static_memberst &)(add(ID_static_members).get_sub());
+  }
+
   bool is_abstract() const
   {
     return get_bool(ID_abstract);