[libc++] Make __type_list variadic (#121117)

This makes these lists signficiantly more readable.

Author: philnik777

libcxx/include/__type_traits/aligned_storage.h

@@ -34,26 +34,23 @@ struct __struct_double4 {
   double __lx[4];
 };
 
-// clang-format off
-typedef __type_list<__align_type<unsigned char>,
-        __type_list<__align_type<unsigned short>,
-        __type_list<__align_type<unsigned int>,
-        __type_list<__align_type<unsigned long>,
-        __type_list<__align_type<unsigned long long>,
-        __type_list<__align_type<double>,
-        __type_list<__align_type<long double>,
-        __type_list<__align_type<__struct_double>,
-        __type_list<__align_type<__struct_double4>,
-        __type_list<__align_type<int*>,
-        __nat
-        > > > > > > > > > > __all_types;
-// clang-format on
+using __all_types =
+    __type_list<__align_type<unsigned char>,
+                __align_type<unsigned short>,
+                __align_type<unsigned int>,
+                __align_type<unsigned long>,
+                __align_type<unsigned long long>,
+                __align_type<double>,
+                __align_type<long double>,
+                __align_type<__struct_double>,
+                __align_type<__struct_double4>,
+                __align_type<int*> >;
 
 template <class _TL, size_t _Len>
 struct __find_max_align;
 
-template <class _Hp, size_t _Len>
-struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
+template <class _Head, size_t _Len>
+struct __find_max_align<__type_list<_Head>, _Len> : public integral_constant<size_t, _Head::value> {};
 
 template <size_t _Len, size_t _A1, size_t _A2>
 struct __select_align {
@@ -65,9 +62,11 @@ struct __select_align {
   static const size_t value = _Len < __max ? __min : __max;
 };
 
-template <class _Hp, class _Tp, size_t _Len>
-struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
-    : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
+template <class _Head, class... _Tail, size_t _Len>
+struct __find_max_align<__type_list<_Head, _Tail...>, _Len>
+    : public integral_constant<
+          size_t,
+          __select_align<_Len, _Head::value, __find_max_align<__type_list<_Tail...>, _Len>::value>::value> {};
 
 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
 struct _LIBCPP_DEPRECATED_IN_CXX23 _LIBCPP_TEMPLATE_VIS aligned_storage {

libcxx/include/__type_traits/make_signed.h

@@ -29,21 +29,17 @@ template <class _Tp>
 using __make_signed_t = __make_signed(_Tp);
 
 #else
-// clang-format off
-typedef __type_list<signed char,
-        __type_list<signed short,
-        __type_list<signed int,
-        __type_list<signed long,
-        __type_list<signed long long,
-#  if _LIBCPP_HAS_INT128
-        __type_list<__int128_t,
-#  endif
-        __nat
+using __signed_types =
+    __type_list<signed char,
+                signed short,
+                signed int,
+                signed long,
+                signed long long
 #  if _LIBCPP_HAS_INT128
-        >
+                ,
+                __int128_t
 #  endif
-        > > > > > __signed_types;
-// clang-format on
+                >;
 
 template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
 struct __make_signed{};

libcxx/include/__type_traits/make_unsigned.h

@@ -31,21 +31,17 @@ template <class _Tp>
 using __make_unsigned_t = __make_unsigned(_Tp);
 
 #else
-// clang-format off
-typedef __type_list<unsigned char,
-        __type_list<unsigned short,
-        __type_list<unsigned int,
-        __type_list<unsigned long,
-        __type_list<unsigned long long,
-#  if _LIBCPP_HAS_INT128
-        __type_list<__uint128_t,
-#  endif
-        __nat
+using __unsigned_types =
+    __type_list<unsigned char,
+                unsigned short,
+                unsigned int,
+                unsigned long,
+                unsigned long long
 #  if _LIBCPP_HAS_INT128
-        >
+                ,
+                __uint128_t
 #  endif
-        > > > > > __unsigned_types;
-// clang-format on
+                >;
 
 template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
 struct __make_unsigned{};

libcxx/include/__type_traits/type_list.h

@@ -11,30 +11,36 @@
 
 #include <__config>
 #include <__cstddef/size_t.h>
+#include <__type_traits/enable_if.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Hp, class _Tp>
-struct __type_list {
-  typedef _Hp _Head;
-  typedef _Tp _Tail;
+template <class... _Types>
+struct __type_list {};
+
+template <class>
+struct __type_list_head;
+
+template <class _Head, class... _Tail>
+struct __type_list_head<__type_list<_Head, _Tail...> > {
+  using type _LIBCPP_NODEBUG = _Head;
 };
 
-template <class _TypeList, size_t _Size, bool = _Size <= sizeof(typename _TypeList::_Head)>
+template <class _TypeList, size_t _Size, bool = _Size <= sizeof(typename __type_list_head<_TypeList>::type)>
 struct __find_first;
 
-template <class _Hp, class _Tp, size_t _Size>
-struct __find_first<__type_list<_Hp, _Tp>, _Size, true> {
-  using type _LIBCPP_NODEBUG = _Hp;
+template <class _Head, class... _Tail, size_t _Size>
+struct __find_first<__type_list<_Head, _Tail...>, _Size, true> {
+  using type _LIBCPP_NODEBUG = _Head;
 };
 
-template <class _Hp, class _Tp, size_t _Size>
-struct __find_first<__type_list<_Hp, _Tp>, _Size, false> {
-  using type _LIBCPP_NODEBUG = typename __find_first<_Tp, _Size>::type;
+template <class _Head, class... _Tail, size_t _Size>
+struct __find_first<__type_list<_Head, _Tail...>, _Size, false> {
+  using type _LIBCPP_NODEBUG = typename __find_first<__type_list<_Tail...>, _Size>::type;
 };
 
 _LIBCPP_END_NAMESPACE_STD