Merge pull request #2692 from diffblue/follow-tags

Follow tag types

Author: Daniel Kroening

src/ansi-c/c_typecast.cpp

@@ -252,21 +252,24 @@ bool check_c_implicit_typecast(
 
 typet c_typecastt::follow_with_qualifiers(const typet &src_type)
 {
-  if(src_type.id()!=ID_symbol)
+  if(
+    src_type.id() != ID_symbol && src_type.id() != ID_struct_tag &&
+    src_type.id() != ID_union_tag)
+  {
     return src_type;
+  }
 
   typet result_type=src_type;
 
   // collect qualifiers
   c_qualifierst qualifiers(src_type);
 
-  while(result_type.id()==ID_symbol)
+  while(result_type.id() == ID_symbol || result_type.id() == ID_struct_tag ||
+        result_type.id() == ID_union_tag)
   {
-    const symbolt &followed_type_symbol =
-      ns.lookup(to_symbol_type(result_type));
-
-    result_type=followed_type_symbol.type;
-    qualifiers+=c_qualifierst(followed_type_symbol.type);
+    const typet &followed_type = ns.follow(result_type);
+    result_type = followed_type;
+    qualifiers += c_qualifierst(followed_type);
   }
 
   qualifiers.write(result_type);

src/ansi-c/c_typecheck_expr.cpp

@@ -524,8 +524,7 @@ void c_typecheck_baset::typecheck_expr_builtin_offsetof(exprt &expr)
 
   forall_operands(m_it, member)
   {
-    if(type.id()==ID_symbol)
-      type=follow(type);
+    type = follow(type);
 
     if(m_it->id()==ID_member)
     {

src/ansi-c/padding.cpp

@@ -82,6 +82,10 @@ mp_integer alignment(const typet &type, const namespacet &ns)
     result=alignment(type.subtype(), ns);
   else if(type.id()==ID_c_enum_tag)
     result=alignment(ns.follow_tag(to_c_enum_tag_type(type)), ns);
+  else if(type.id() == ID_struct_tag)
+    result = alignment(ns.follow_tag(to_struct_tag_type(type)), ns);
+  else if(type.id() == ID_union_tag)
+    result = alignment(ns.follow_tag(to_union_tag_type(type)), ns);
   else if(type.id()==ID_symbol)
     result=alignment(ns.follow(type), ns);
   else if(type.id()==ID_c_bit_field)

src/util/namespace.cpp

@@ -54,6 +54,12 @@ const symbolt &namespace_baset::lookup(const tag_typet &type) const
 
 const typet &namespace_baset::follow(const typet &src) const
 {
+  if(src.id() == ID_union_tag)
+    return follow_tag(to_union_tag_type(src));
+
+  if(src.id() == ID_struct_tag)
+    return follow_tag(to_struct_tag_type(src));
+
   if(src.id()!=ID_symbol)
     return src;
 

src/util/pointer_offset_size.cpp

@@ -238,6 +238,14 @@ mp_integer pointer_offset_bits(
   {
     return pointer_offset_bits(ns.follow(type), ns);
   }
+  else if(type.id() == ID_union_tag)
+  {
+    return pointer_offset_bits(ns.follow_tag(to_union_tag_type(type)), ns);
+  }
+  else if(type.id() == ID_struct_tag)
+  {
+    return pointer_offset_bits(ns.follow_tag(to_struct_tag_type(type)), ns);
+  }
   else if(type.id()==ID_code)
   {
     return 0;
@@ -506,6 +514,14 @@ exprt size_of_expr(
   {
     return size_of_expr(ns.follow(type), ns);
   }
+  else if(type.id() == ID_union_tag)
+  {
+    return size_of_expr(ns.follow_tag(to_union_tag_type(type)), ns);
+  }
+  else if(type.id() == ID_struct_tag)
+  {
+    return size_of_expr(ns.follow_tag(to_struct_tag_type(type)), ns);
+  }
   else if(type.id()==ID_code)
   {
     return from_integer(0, size_type());

src/util/std_types.h

@@ -553,13 +553,13 @@ class struct_tag_typet:public tag_typet
   }
 };
 
-/*! \brief Cast a generic typet to a \ref union_tag_typet
+/*! \brief Cast a generic typet to a \ref struct_tag_typet
  *
  * This is an unchecked conversion. \a type must be known to be \ref
- * union_tag_typet.
+ * struct_tag_typet.
  *
  * \param type Source type
- * \return Object of type \ref union_tag_typet
+ * \return Object of type \ref struct_tag_typet
  *
  * \ingroup gr_std_types
 */