Use type_try_dynamic_cast instead of direct id check and cast

Author: svorenova

src/util/type_eq.cpp

@@ -32,18 +32,18 @@ bool type_eq(const typet &type1, const typet &type2, const namespacet &ns)
   if(type1==type2)
     return true;
 
-  if(type1.id() == ID_symbol_type)
+  if(const auto symbol_type1 = type_try_dynamic_cast<symbol_typet>(type1))
   {
-    const symbolt &symbol = ns.lookup(to_symbol_type(type1));
+    const symbolt &symbol = ns.lookup(*symbol_type1);
     if(!symbol.is_type)
       throw "symbol "+id2string(symbol.name)+" is not a type";
 
     return type_eq(symbol.type, type2, ns);
   }
 
-  if(type2.id() == ID_symbol_type)
+  if(const auto symbol_type2 = type_try_dynamic_cast<symbol_typet>(type2))
   {
-    const symbolt &symbol = ns.lookup(to_symbol_type(type2));
+    const symbolt &symbol = ns.lookup(*symbol_type2);
     if(!symbol.is_type)
       throw "symbol "+id2string(symbol.name)+" is not a type";