Consistently resize instead of just reserving in codet classes

Author: tautschnig

src/util/std_code.h

@@ -281,8 +281,7 @@ class code_assumet:public codet
 public:
   inline code_assumet():codet(ID_assume)
   {
-    // will change to resize(1) in the future
-    reserve_operands(1);
+    operands().resize(1);
   }
 
   inline explicit code_assumet(const exprt &expr):codet(ID_assume)
@@ -320,8 +319,7 @@ class code_assertt:public codet
 public:
   inline code_assertt():codet(ID_assert)
   {
-    // will change to resize(1) in the future
-    reserve_operands(1);
+    operands().resize(1);
   }
 
   inline explicit code_assertt(const exprt &expr):codet(ID_assert)
@@ -723,7 +721,8 @@ class code_returnt:public codet
 public:
   inline code_returnt():codet(ID_return)
   {
-    reserve_operands(1);
+    operands().resize(1);
+    op0().make_nil();
   }
 
   explicit inline code_returnt(const exprt &_op):codet(ID_return)
@@ -738,13 +737,14 @@ class code_returnt:public codet
 
   inline exprt &return_value()
   {
-    operands().resize(1);
     return op0();
   }
 
   inline bool has_return_value() const
   {
-    return operands().size()==1;
+    if(operands().empty())
+      return false; // backwards compatibility
+    return return_value().is_not_nil();
   }
 };