Swap order of subtypes in construction of merged_type nodes

Main type needs to be at the end.
Handle and record GCC function attribute noreturn.

src/cpp/cpp_convert_type.cpp

@@ -30,7 +30,7 @@ class cpp_convert_typet
   unsigned unsigned_cnt, signed_cnt, char_cnt, int_cnt, short_cnt,
            long_cnt, const_cnt, restrict_cnt, constexpr_cnt, volatile_cnt,
            double_cnt, float_cnt, complex_cnt, cpp_bool_cnt, proper_bool_cnt,
-           extern_cnt, wchar_t_cnt, char16_t_cnt, char32_t_cnt,
+           extern_cnt, noreturn_cnt, wchar_t_cnt, char16_t_cnt, char32_t_cnt,
            int8_cnt, int16_cnt, int32_cnt, int64_cnt, ptr32_cnt, ptr64_cnt,
            float128_cnt, int128_cnt;
 
@@ -53,7 +53,7 @@ void cpp_convert_typet::read(const typet &type)
   unsigned_cnt=signed_cnt=char_cnt=int_cnt=short_cnt=
   long_cnt=const_cnt=restrict_cnt=constexpr_cnt=volatile_cnt=
   double_cnt=float_cnt=complex_cnt=cpp_bool_cnt=proper_bool_cnt=
-  extern_cnt=wchar_t_cnt=char16_t_cnt=char32_t_cnt=
+  extern_cnt=noreturn_cnt=wchar_t_cnt=char16_t_cnt=char32_t_cnt=
   int8_cnt=int16_cnt=int32_cnt=int64_cnt=
   ptr32_cnt=ptr64_cnt=float128_cnt=int128_cnt=0;
 
@@ -132,6 +132,10 @@ void cpp_convert_typet::read_rec(const typet &type)
     constexpr_cnt++;
   else if(type.id()==ID_extern)
     extern_cnt++;
+  else if(type.id()==ID_noreturn)
+  {
+    noreturn_cnt++;
+  }
   else if(type.id()==ID_function_type)
   {
     read_function_type(type);

src/cpp/parse.cpp

@@ -480,7 +480,12 @@ void Parser::merge_types(const typet &src, typet &dest)
       dest=tmp;
     }
 
-    dest.copy_to_subtypes(src);
+    // the end of the subtypes container needs to stay the same,
+    // since several analysis functions traverse via the end for
+    // merged_types
+    typet::subtypest &sub=dest.subtypes();
+    sub.emplace(sub.begin(), src);
+    POSTCONDITION(!dest.subtypes().empty());
   }
 }
 
@@ -3199,12 +3204,9 @@ bool Parser::optPtrOperator(typet &ptrs)
       cv.make_nil();
       optCvQualify(cv); // the qualifier is for the pointer
       if(cv.is_not_nil())
-      {
-        merge_types(op, cv);
-        t_list.push_back(cv);
-      }
-      else
-        t_list.push_back(op);
+        merge_types(cv, op);
+
+      t_list.push_back(op);
     }
     else if(t=='^')
     {
@@ -3218,12 +3220,9 @@ bool Parser::optPtrOperator(typet &ptrs)
       cv.make_nil();
       optCvQualify(cv); // the qualifier is for the pointer
       if(cv.is_not_nil())
-      {
-        merge_types(op, cv);
-        t_list.push_back(cv);
-      }
-      else
-        t_list.push_back(op);
+        merge_types(cv, op);
+
+      t_list.push_back(op);
     }
     else if(isPtrToMember(0))
     {