Adds missing case to assigns clause type checking

Signed-off-by: Felipe R. Monteiro <[email protected]>

Author: feliperodri

src/ansi-c/ansi_c_convert_type.cpp

@@ -257,10 +257,11 @@ void ansi_c_convert_typet::read_rec(const typet &type)
     {
       if(
         operand.id() != ID_symbol && operand.id() != ID_ptrmember &&
-        operand.id() != ID_dereference)
+        operand.id() != ID_member && operand.id() != ID_dereference)
       {
         error().source_location = source_location;
-        error() << "illegal target in assigns clause" << eom;
+        error() << "illegal target (" << operand.id_string()
+                << ") in assigns clause" << eom;
         throw 0;
       }
     }