Replace use of deprecated nil_typet in get_type

Use optionalt<typet> as recommended in the deprecation note.

Author: tautschnig

src/goto-programs/builtin_functions.cpp

@@ -260,26 +260,26 @@ void goto_convertt::do_scanf(
 
       for(const auto &t : token_list)
       {
-        typet type=get_type(t);
+        const auto type = get_type(t);
 
-        if(type.is_not_nil())
+        if(type.has_value())
         {
           if(argument_number<arguments.size())
           {
             const typecast_exprt ptr(
-              arguments[argument_number], pointer_type(type));
+              arguments[argument_number], pointer_type(*type));
             argument_number++;
 
-            if(type.id()==ID_array)
+            if(type->id() == ID_array)
             {
               #if 0
               // A string. We first need a nondeterministic size.
               exprt size=side_effect_expr_nondett(size_type());
-              to_array_type(type).size()=size;
+              to_array_type(*type).size()=size;
 
               const symbolt &tmp_symbol=
                 new_tmp_symbol(
-                  type, "scanf_string", dest, function.source_location());
+                  *type, "scanf_string", dest, function.source_location());
 
               const address_of_exprt rhs(
                 index_exprt(
@@ -298,9 +298,9 @@ void goto_convertt::do_scanf(
               copy(array_copy_statement, OTHER, dest);
               #else
               const index_exprt new_lhs(
-                dereference_exprt(ptr, type), from_integer(0, index_type()));
+                dereference_exprt(ptr, *type), from_integer(0, index_type()));
               const side_effect_expr_nondett rhs(
-                type.subtype(), function.source_location());
+                type->subtype(), function.source_location());
               code_assignt assign(new_lhs, rhs);
               assign.add_source_location()=function.source_location();
               copy(assign, ASSIGN, dest);
@@ -309,9 +309,9 @@ void goto_convertt::do_scanf(
             else
             {
               // make it nondet for now
-              const dereference_exprt new_lhs(ptr, type);
+              const dereference_exprt new_lhs(ptr, *type);
               const side_effect_expr_nondett rhs(
-                type, function.source_location());
+                *type, function.source_location());
               code_assignt assign(new_lhs, rhs);
               assign.add_source_location()=function.source_location();
               copy(assign, ASSIGN, dest);

src/goto-programs/format_strings.cpp

@@ -226,7 +226,7 @@ format_token_listt parse_format_string(const std::string &arg_string)
   return token_list;
 }
 
-typet get_type(const format_tokent &token)
+optionalt<typet> get_type(const format_tokent &token)
 {
   switch(token.type)
   {
@@ -291,7 +291,7 @@ typet get_type(const format_tokent &token)
     }
 
   default:
-    return nil_typet();
+    return {};
   }
 
   UNREACHABLE;

src/goto-programs/format_strings.h

@@ -88,6 +88,6 @@ typedef std::list<format_tokent> format_token_listt;
 
 format_token_listt parse_format_string(const std::string &);
 
-typet get_type(const format_tokent &);
+optionalt<typet> get_type(const format_tokent &);
 
 #endif // CPROVER_GOTO_PROGRAMS_FORMAT_STRINGS_H