CONTRACTS: use goto_programt::get_decl_identifiers

Author: Remi Delmas

src/goto-instrument/contracts/cfg_info.h

@@ -202,18 +202,14 @@ class goto_program_cfg_infot : public cfg_infot
   explicit goto_program_cfg_infot(const goto_programt &goto_program)
   {
     // collect symbols declared in the insruction sequence as locals
-    for(const auto &instruction : goto_program.instructions)
-    {
-      if(instruction.is_decl())
-        locals.insert(instruction.decl_symbol().get_identifier());
-    }
+    goto_program.get_decl_identifiers(locals);
 
     // collect dirty locals
     goto_functiont goto_function;
     goto_function.body.copy_from(goto_program);
 
     dirtyt is_dirty(goto_function);
-    auto dirty_ids = is_dirty.get_dirty_ids();
+    const auto &dirty_ids = is_dirty.get_dirty_ids();
     dirty.insert(dirty_ids.begin(), dirty_ids.end());
   }
 
@@ -234,8 +230,8 @@ class goto_program_cfg_infot : public cfg_infot
   }
 
 protected:
-  std::unordered_set<irep_idt> locals;
-  std::unordered_set<irep_idt> dirty;
+  std::set<irep_idt> locals;
+  std::set<irep_idt> dirty;
 };
 
 #endif