C and jsil front-ends: make to_symbol return by value

Instead of creating and dummy-initialising a symbolt upfront, return a
locally allocated symbol.

This removes the last users of symbolt::clear, which had maintenance
risks in that it had to list all members.

Author: tautschnig

src/ansi-c/ansi_c_declaration.cpp

@@ -123,14 +123,11 @@ typet ansi_c_declarationt::full_type(
   return result;
 }
 
-void ansi_c_declarationt::to_symbol(
-  const ansi_c_declaratort &declarator,
-  symbolt &symbol) const
+symbolt
+ansi_c_declarationt::to_symbol(const ansi_c_declaratort &declarator) const
 {
-  symbol.clear();
+  symbolt symbol{declarator.get_name(), full_type(declarator), ID_C};
   symbol.value=declarator.value();
-  symbol.type=full_type(declarator);
-  symbol.name=declarator.get_name();
   symbol.pretty_name=symbol.name;
   symbol.base_name=declarator.get_base_name();
   symbol.is_type=get_is_typedef();
@@ -194,4 +191,6 @@ void ansi_c_declarationt::to_symbol(
       (get_is_global() && get_is_static() && !get_is_used()) ||
       symbol.is_parameter;
   }
+
+  return symbol;
 }

src/ansi-c/ansi_c_declaration.h

@@ -205,9 +205,7 @@ class ansi_c_declarationt:public exprt
     set(ID_is_used, is_used);
   }
 
-  void to_symbol(
-    const ansi_c_declaratort &,
-    symbolt &symbol) const;
+  symbolt to_symbol(const ansi_c_declaratort &) const;
 
   typet full_type(const ansi_c_declaratort &) const;
 

src/ansi-c/c_typecheck_base.cpp

@@ -658,8 +658,7 @@ void c_typecheck_baset::typecheck_declaration(
       declaration.set_is_weak(full_spec.is_weak);
       declaration.set_is_used(full_spec.is_used);
 
-      symbolt symbol;
-      declaration.to_symbol(declarator, symbol);
+      symbolt symbol = declaration.to_symbol(declarator);
       current_symbol=symbol;
 
       // now check other half of type

src/jsil/jsil_convert.cpp

@@ -42,8 +42,7 @@ bool jsil_convertt::operator()(
       it!=parse_tree.items.end();
       ++it)
   {
-    symbolt new_symbol;
-    it->to_symbol(new_symbol);
+    symbolt new_symbol = it->to_symbol();
 
     if(convert_code(new_symbol, to_code(new_symbol.value)))
       return true;

src/jsil/jsil_parse_tree.cpp

@@ -40,10 +40,8 @@ static bool insert_at_label(
   return true;
 }
 
-void jsil_declarationt::to_symbol(symbolt &symbol) const
+symbolt jsil_declarationt::to_symbol() const
 {
-  symbol.clear();
-
   symbol_exprt s(to_symbol_expr(
       static_cast<const exprt&>(find(ID_declarator))));
 
@@ -56,10 +54,8 @@ void jsil_declarationt::to_symbol(symbolt &symbol) const
   else if(proc_type=="spec")
     symbol_type=jsil_spec_code_typet(symbol_type);
 
-  symbol.name=s.get_identifier();
+  symbolt symbol{s.get_identifier(), symbol_type, "jsil"};
   symbol.base_name=s.get_identifier();
-  symbol.mode="jsil";
-  symbol.type=symbol_type;
   symbol.location=s.source_location();
 
   code_blockt code(to_code_block(
@@ -79,6 +75,8 @@ void jsil_declarationt::to_symbol(symbolt &symbol) const
     throw "throw label "+throws.get_string(ID_label)+" not found";
 
   symbol.value.swap(code);
+
+  return symbol;
 }
 
 void jsil_declarationt::output(std::ostream &out) const

src/jsil/jsil_parse_tree.h

@@ -92,7 +92,7 @@ class jsil_declarationt:public exprt
     return static_cast<code_blockt &>(add(ID_value));
   }
 
-  void to_symbol(symbolt &symbol) const;
+  symbolt to_symbol() const;
 
   void output(std::ostream &) const;
 };

src/util/symbol.h

@@ -91,22 +91,6 @@ class symbolt
     location.make_nil();
   }
 
-  /// Zero initialise a symbol object.
-  void clear()
-  {
-    type.make_nil();
-    value.make_nil();
-    location.make_nil();
-
-    name=module=base_name=mode=pretty_name=irep_idt();
-
-    is_type=is_macro=is_exported=
-    is_input=is_output=is_state_var=is_property=
-    is_static_lifetime=is_thread_local=
-    is_lvalue=is_file_local=is_extern=is_volatile=
-    is_parameter=is_auxiliary=is_weak=false;
-  }
-
   void swap(symbolt &b);
   void show(std::ostream &out) const;