Use correct function return identifier of functions without body

in trace output

Author: peterschrammel

src/goto-programs/json_goto_trace.cpp

@@ -263,9 +263,7 @@ void convert_return(
   json_call_return["internal"] = jsont::json_boolean(step.internal);
   json_call_return["thread"] = json_numbert(std::to_string(step.thread_nr));
 
-  const irep_idt &function_identifier =
-    (step.type == goto_trace_stept::typet::FUNCTION_CALL) ? step.called_function
-                                                          : step.function_id;
+  const irep_idt &function_identifier = step.called_function;
 
   const symbolt &symbol = ns.lookup(function_identifier);
   json_call_return["function"] =

src/goto-programs/xml_goto_trace.cpp

@@ -186,11 +186,11 @@ void convert(
         xml_call_return.set_attribute("thread", std::to_string(step.thread_nr));
         xml_call_return.set_attribute("step_nr", std::to_string(step.step_nr));
 
-        const symbolt &symbol = ns.lookup(step.function_id);
+        const symbolt &symbol = ns.lookup(step.called_function);
         xmlt &xml_function=xml_call_return.new_element("function");
         xml_function.set_attribute(
           "display_name", id2string(symbol.display_name()));
-        xml_function.set_attribute("identifier", id2string(step.function_id));
+        xml_function.set_attribute("identifier", id2string(symbol.name));
         xml_function.new_element()=xml(symbol.location);
 
         if(xml_location.name!="")