Clean-up irep-id emptyness checks in goto-symex

Author: peterschrammel

src/goto-symex/symex_builtin_functions.cpp

@@ -221,7 +221,7 @@ void goto_symext::symex_gcc_builtin_va_arg_next(
 
   exprt rhs=zero_initializer(lhs.type(), code.source_location(), ns);
 
-  if(id!=irep_idt())
+  if(!id.empty())
   {
     // strip last name off id to get function name
     std::size_t pos=id2string(id).rfind("::");

src/goto-symex/symex_function_call.cpp

@@ -62,7 +62,7 @@ void goto_symext::parameter_assignments(
 
     const irep_idt &identifier=parameter.get_identifier();
 
-    if(identifier==irep_idt())
+    if(identifier.empty())
       throw "no identifier for function parameter";
 
     const symbolt &symbol=ns.lookup(identifier);