Make struct_union_typet::component_type return a const reference

There is no need for a copy.

Author: tautschnig

jbmc/src/java_bytecode/java_string_library_preprocess.cpp

@@ -392,7 +392,8 @@ java_string_library_preprocesst::process_equals_function_operands(
 /// \param type: a type containing a "data" component
 /// \param symbol_table: symbol table
 /// \return type of the "data" component
-static typet get_data_type(const typet &type, const symbol_tablet &symbol_table)
+static const typet&
+get_data_type(const typet &type, const symbol_tablet &symbol_table)
 {
   PRECONDITION(type.id() == ID_struct || type.id() == ID_symbol_type);
   if(type.id() == ID_symbol_type)
@@ -410,7 +411,7 @@ static typet get_data_type(const typet &type, const symbol_tablet &symbol_table)
 /// \param type: a type containing a "length" component
 /// \param symbol_table: symbol table
 /// \return type of the "length" component
-static typet
+static const typet&
 get_length_type(const typet &type, const symbol_tablet &symbol_table)
 {
   PRECONDITION(type.id() == ID_struct || type.id() == ID_symbol_type);

src/pointer-analysis/value_set.cpp

@@ -1756,7 +1756,7 @@ exprt value_sett::make_member(
   }
 
   // give up
-  typet subtype=struct_union_type.component_type(component_name);
+  const typet &subtype = struct_union_type.component_type(component_name);
   member_exprt member_expr(src, component_name, subtype);
 
   return member_expr;

src/util/std_types.cpp

@@ -72,10 +72,10 @@ const struct_union_typet::componentt &struct_union_typet::get_component(
   return static_cast<const componentt &>(get_nil_irep());
 }
 
-typet struct_union_typet::component_type(
+const typet &struct_union_typet::component_type(
   const irep_idt &component_name) const
 {
-  const exprt c=get_component(component_name);
+  const auto &c = get_component(component_name);
   assert(c.is_not_nil());
   return c.type();
 }

src/util/std_types.h

@@ -212,7 +212,7 @@ class struct_union_typet:public typet
     const irep_idt &component_name) const;
 
   std::size_t component_number(const irep_idt &component_name) const;
-  typet component_type(const irep_idt &component_name) const;
+  const typet &component_type(const irep_idt &component_name) const;
 
   irep_idt get_tag() const { return get(ID_tag); }
   void set_tag(const irep_idt &tag) { set(ID_tag, tag); }