bits2expr must return an expression of the requested type

Do not return the expanded version of the type.

Author: tautschnig

src/util/simplify_expr.cpp

@@ -1431,12 +1431,10 @@ bool simplify_exprt::simplify_object(exprt &expr)
 
 exprt simplify_exprt::bits2expr(
   const std::string &bits,
-  const typet &_type,
+  const typet &type,
   bool little_endian)
 {
   // bits start at lowest memory address
-  const typet &type=ns.follow(_type);
-
   auto type_bits = pointer_offset_bits(type, ns);
 
   if(!type_bits.has_value() || *type_bits != bits.size())
@@ -1461,15 +1459,18 @@ exprt simplify_exprt::bits2expr(
   else if(type.id()==ID_c_enum)
   {
     exprt val = bits2expr(bits, to_c_enum_type(type).subtype(), little_endian);
-    val.type()=type;
+    val.type() = type;
     return val;
   }
   else if(type.id()==ID_c_enum_tag)
-    return
-      bits2expr(
+  {
+    exprt val = bits2expr(
         bits,
         ns.follow_tag(to_c_enum_tag_type(type)),
         little_endian);
+    val.type() = type;
+    return val;
+  }
   else if(type.id()==ID_union)
   {
     // find a suitable member
@@ -1486,6 +1487,15 @@ exprt simplify_exprt::bits2expr(
       return union_exprt(component.get_name(), val, type);
     }
   }
+  else if(type.id()==ID_union_tag)
+  {
+    exprt val = bits2expr(
+        bits,
+        ns.follow_tag(to_union_tag_type(type)),
+        little_endian);
+    val.type() = type;
+    return val;
+  }
   else if(type.id()==ID_struct)
   {
     const struct_typet &struct_type=to_struct_type(type);
@@ -1516,6 +1526,15 @@ exprt simplify_exprt::bits2expr(
 
     return std::move(result);
   }
+  else if(type.id()==ID_struct_tag)
+  {
+    exprt val = bits2expr(
+        bits,
+        ns.follow_tag(to_struct_tag_type(type)),
+        little_endian);
+    val.type() = type;
+    return val;
+  }
   else if(type.id()==ID_array)
   {
     const array_typet &array_type=to_array_type(type);