Cleanup use of empty strings

jbmc/src/janalyzer/janalyzer_parse_options.cpp

@@ -405,7 +405,7 @@ int janalyzer_parse_optionst::perform_analysis(const optionst &options)
 
     if(cmdline.isset("show-taint"))
     {
-      taint_analysis(goto_model, taint_file, ui_message_handler, true, "");
+      taint_analysis(goto_model, taint_file, ui_message_handler, true);
       return CPROVER_EXIT_SUCCESS;
     }
     else

jbmc/src/java_bytecode/expr2java.cpp

@@ -246,8 +246,7 @@ std::string expr2javat::convert_rec(
   qualifierst &new_qualifiers = *clone;
   new_qualifiers.read(src);
 
-  const std::string d=
-    declarator==""?declarator:(" "+declarator);
+  const std::string d = declarator.empty() ? declarator : (" " + declarator);
 
   const std::string q=
     new_qualifiers.as_string();
@@ -278,7 +277,7 @@ std::string expr2javat::convert_rec(
     // so we make one up, loosely inspired by the syntax
     // of lambda expressions.
 
-    std::string dest="";
+    std::string dest;
 
     dest+='(';
     const java_method_typet::parameterst &parameters = method_type.parameters();

jbmc/src/java_bytecode/java_entry_point.cpp

@@ -542,7 +542,7 @@ main_function_resultt get_main_symbol(
     irep_idt main_symbol_id = resolve_friendly_method_name(
       config.main.value(), symbol_table, error_message);
 
-    if(main_symbol_id==irep_idt())
+    if(main_symbol_id.empty())
     {
       message.error()
         << "main symbol resolution failed: " << error_message << messaget::eom;

jbmc/src/java_bytecode/java_object_factory.cpp

@@ -290,7 +290,7 @@ class recursion_set_entryt
   /// Removes erase_entry (if set) from the controlled set.
   ~recursion_set_entryt()
   {
-    if(erase_entry!=irep_idt())
+    if(!erase_entry.empty())
       recursion_set.erase(erase_entry);
   }
 
@@ -303,10 +303,8 @@ class recursion_set_entryt
   /// \return true if added to the set (and therefore owned by this object)
   bool insert_entry(const irep_idt &entry)
   {
-    INVARIANT(
-      erase_entry==irep_idt(),
-      "insert_entry should only be called once");
-    INVARIANT(entry!=irep_idt(), "entry should be a struct tag");
+    INVARIANT(erase_entry.empty(), "insert_entry should only be called once");
+    INVARIANT(!entry.empty(), "entry should be a struct tag");
     bool ret=recursion_set.insert(entry).second;
     if(ret)
     {

jbmc/src/java_bytecode/java_string_library_preprocess.cpp

@@ -41,7 +41,7 @@ static irep_idt get_tag(const typet &type)
   else if(type.id() == ID_struct)
     return irep_idt("java::" + id2string(to_struct_type(type).get_tag()));
   else
-    return "";
+    return irep_idt();
 }
 
 /// \param type: a type

jbmc/unit/java-testing-utils/require_type.cpp

@@ -470,7 +470,7 @@ require_type::require_struct_tag(const typet &type, const irep_idt &identifier)
 {
   REQUIRE(type.id() == ID_struct_tag);
   const struct_tag_typet &result = to_struct_tag_type(type);
-  if(identifier != "")
+  if(!identifier.empty())
   {
     REQUIRE(result.get_identifier() == identifier);
   }

jbmc/unit/java_bytecode/java_types/java_type_from_string.cpp

@@ -15,7 +15,7 @@ SCENARIO("java_type_from_string", "[core][java_types]")
 
   GIVEN("Ljava/lang/Integer;")
   {
-    const auto integer_type = java_type_from_string("Ljava/lang/Integer;", "");
+    const auto integer_type = java_type_from_string("Ljava/lang/Integer;");
     REQUIRE(integer_type.has_value());
   }
 
@@ -35,7 +35,7 @@ SCENARIO("java_type_from_string", "[core][java_types]")
   GIVEN("Ljava/util/List<Ljava/lang/Integer>;")
   {
     const auto integer_list_type =
-      java_type_from_string("Ljava/util/List<Ljava/lang/Integer;>;", "");
+      java_type_from_string("Ljava/util/List<Ljava/lang/Integer;>;");
     REQUIRE(integer_list_type.has_value());
   }
 

src/analyses/ai.h

@@ -157,7 +157,7 @@ class ai_baset
     const goto_functionst::goto_functiont &goto_function,
     std::ostream &out) const
   {
-    output(ns, "", goto_function.body, out);
+    output(ns, irep_idt(), goto_function.body, out);
   }
 
   /// Output the abstract states for the whole program as JSON
@@ -178,15 +178,15 @@ class ai_baset
     const namespacet &ns,
     const goto_programt &goto_program) const
   {
-    return output_json(ns, "", goto_program);
+    return output_json(ns, irep_idt(), goto_program);
   }
 
   /// Output the abstract states for a single function as JSON
   jsont output_json(
     const namespacet &ns,
     const goto_functionst::goto_functiont &goto_function) const
   {
-    return output_json(ns, "", goto_function.body);
+    return output_json(ns, irep_idt(), goto_function.body);
   }
 
   /// Output the abstract states for the whole program as XML
@@ -207,15 +207,15 @@ class ai_baset
     const namespacet &ns,
     const goto_programt &goto_program) const
   {
-    return output_xml(ns, "", goto_program);
+    return output_xml(ns, irep_idt(), goto_program);
   }
 
   /// Output the abstract states for a single function as XML
   xmlt output_xml(
     const namespacet &ns,
     const goto_functionst::goto_functiont &goto_function) const
   {
-    return output_xml(ns, "", goto_function.body);
+    return output_xml(ns, irep_idt(), goto_function.body);
   }
 
 protected:

src/analyses/goto_rw.cpp

@@ -671,7 +671,7 @@ void guarded_range_domaint::output(
     out << itr->first << ":" << itr->second.first;
     // we don't know what mode (language) we are in, so we rely on the default
     // language to be reasonable for from_expr
-    out << " if " << from_expr(ns, "", itr->second.second);
+    out << " if " << from_expr(ns, irep_idt(), itr->second.second);
   }
   out << "]";
 }

src/analyses/invariant_set.cpp

@@ -63,8 +63,7 @@ bool inv_object_storet::get(const exprt &expr, unsigned &n)
 unsigned inv_object_storet::add(const exprt &expr)
 {
   std::string s=build_string(expr);
-
-  assert(s!="");
+  CHECK_RETURN(!s.empty());
 
   mapt::number_type n=map.number(s);
 
@@ -137,7 +136,7 @@ std::string inv_object_storet::build_string(const exprt &expr) const
   // we don't know what mode (language) we are in, so we rely on the default
   // language to be reasonable for from_expr
   if(is_constant_address(expr))
-    return from_expr(ns, "", expr);
+    return from_expr(ns, irep_idt(), expr);
 
   if(expr.id()==ID_member)
   {
@@ -391,8 +390,8 @@ void invariant_sett::strengthen_rec(const exprt &expr)
     throw "non-Boolean argument to strengthen()";
 
   #if 0
-  std::cout << "S: " << from_expr(*ns, "", expr) << '\n';
-  #endif
+  std::cout << "S: " << from_expr(*ns, irep_idt(), expr) << '\n';
+#endif
 
   if(is_false)
   {
@@ -594,8 +593,8 @@ tvt invariant_sett::implies_rec(const exprt &expr) const
     throw "implies: non-Boolean expression";
 
   #if 0
-  std::cout << "I: " << from_expr(*ns, "", expr) << '\n';
-  #endif
+  std::cout << "I: " << from_expr(*ns, irep_idt(), expr) << '\n';
+#endif
 
   if(is_false) // can't get any stronger
     return tvt(true);

src/analyses/local_bitvector_analysis.cpp

@@ -347,7 +347,7 @@ void local_bitvector_analysist::output(
     }
 
     out << "\n";
-    goto_function.body.output_instruction(ns, "", out, *i_it);
+    goto_function.body.output_instruction(ns, irep_idt(), out, *i_it);
     out << "\n";
 
     l++;

src/analyses/local_may_alias.cpp

@@ -458,7 +458,7 @@ void local_may_aliast::output(
           if(loc_info.aliases.find(j)==i)
           {
             assert(j<objects.size());
-            irep_idt identifier = "";
+            irep_idt identifier;
             if(objects[j].id() == ID_symbol)
               identifier = to_symbol_expr(objects[j]).get_identifier();
             out << ' ' << from_expr(ns, identifier, objects[j]);
@@ -470,7 +470,7 @@ void local_may_aliast::output(
     }
 
     out << "\n";
-    goto_function.body.output_instruction(ns, "", out, *i_it);
+    goto_function.body.output_instruction(ns, irep_idt(), out, *i_it);
     out << "\n";
 
     l++;

src/analyses/local_safe_pointers.cpp

@@ -207,7 +207,7 @@ void local_safe_pointerst::output(
     }
 
     out << '\n';
-    goto_program.output_instruction(ns, "", out, *i_it);
+    goto_program.output_instruction(ns, irep_idt(), out, *i_it);
     out << '\n';
   }
 }
@@ -258,7 +258,7 @@ void local_safe_pointerst::output_safe_dereferences(
     }
 
     out << '\n';
-    goto_program.output_instruction(ns, "", out, *i_it);
+    goto_program.output_instruction(ns, irep_idt(), out, *i_it);
     out << '\n';
   }
 }

src/analyses/static_analysis.h

@@ -155,7 +155,7 @@ class static_analysis_baset
     const goto_programt &goto_program,
     std::ostream &out) const
   {
-    output(goto_program, "", out);
+    output(goto_program, irep_idt(), out);
   }
 
   virtual bool has_location(locationt l) const=0;

src/ansi-c/ansi_c_language.cpp

@@ -43,7 +43,7 @@ bool ansi_c_languaget::preprocess(
   std::ostream &outstream)
 {
   // stdin?
-  if(path=="")
+  if(path.empty())
     return c_preprocess(instream, outstream, get_message_handler());
 
   return c_preprocess(path, outstream, get_message_handler());

src/ansi-c/ansi_c_parser.cpp

@@ -106,7 +106,7 @@ void ansi_c_parsert::add_declarator(
   }
 
   // global?
-  if(current_scope().prefix=="")
+  if(current_scope().prefix.empty())
     ansi_c_declaration.set_is_global(true);
 
   // abstract?

src/ansi-c/c_preprocess.cpp

@@ -200,9 +200,9 @@ static void error_parse_line(
     if(state==2)
     {
       saved_error_location.set_file(file);
-      saved_error_location.set_function("");
+      saved_error_location.set_function(irep_idt());
       saved_error_location.set_line(line_no);
-      saved_error_location.set_column("");
+      saved_error_location.set_column(irep_idt());
     }
   }