From c5fcc3ae39922ed1ab935112c5ffab977ce20087 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser@berlin.de>
Date: Fri, 18 Jul 2025 10:42:30 +0200
Subject: [PATCH] [libc++] Refactor internal index_sequence API to match the
 public one

---
 libcxx/include/CMakeLists.txt                 |   1 -
 libcxx/include/__functional/bind.h            |  21 ++--
 .../__memory_resource/polymorphic_allocator.h |  10 +-
 libcxx/include/__mutex/once_flag.h            |  11 +-
 libcxx/include/__thread/thread.h              |   7 +-
 libcxx/include/__tuple/make_tuple_types.h     |  25 ++--
 libcxx/include/__tuple/tuple_element.h        |   1 -
 libcxx/include/__tuple/tuple_indices.h        |  37 ------
 libcxx/include/__utility/integer_sequence.h   |  68 +++++------
 libcxx/include/__utility/pair.h               |  10 +-
 libcxx/include/bitset                         |  10 +-
 libcxx/include/future                         |   9 +-
 libcxx/include/module.modulemap.in            |   1 -
 libcxx/include/mutex                          |   7 +-
 libcxx/include/scoped_allocator               |  10 +-
 libcxx/include/tuple                          | 113 +++++++++---------
 libcxx/include/variant                        |   4 +-
 .../tuple.apply/make_from_tuple.pass.cpp      |   2 +-
 18 files changed, 139 insertions(+), 208 deletions(-)
 delete mode 100644 libcxx/include/__tuple/tuple_indices.h

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 25b567df2dd33..9bace57c4b7f1 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -780,7 +780,6 @@ set(files
   __tuple/make_tuple_types.h
   __tuple/sfinae_helpers.h
   __tuple/tuple_element.h
-  __tuple/tuple_indices.h
   __tuple/tuple_like.h
   __tuple/tuple_like_ext.h
   __tuple/tuple_like_no_subrange.h
diff --git a/libcxx/include/__functional/bind.h b/libcxx/include/__functional/bind.h
index 596cce03cdb58..def9e4c4ec7a9 100644
--- a/libcxx/include/__functional/bind.h
+++ b/libcxx/include/__functional/bind.h
@@ -83,15 +83,14 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& __mu(reference_w
 
 template <class _Ti, class... _Uj, size_t... _Indx>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __invoke_result_t<_Ti&, _Uj...>
-__mu_expand(_Ti& __ti, tuple<_Uj...>& __uj, __tuple_indices<_Indx...>) {
+__mu_expand(_Ti& __ti, tuple<_Uj...>& __uj, __index_sequence<_Indx...>) {
   return __ti(std::forward<_Uj>(std::get<_Indx>(__uj))...);
 }
 
 template <class _Ti, class... _Uj, __enable_if_t<is_bind_expression<_Ti>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __invoke_result_t<_Ti&, _Uj...>
 __mu(_Ti& __ti, tuple<_Uj...>& __uj) {
-  typedef typename __make_tuple_indices<sizeof...(_Uj)>::type __indices;
-  return std::__mu_expand(__ti, __uj, __indices());
+  return std::__mu_expand(__ti, __uj, __make_index_sequence<sizeof...(_Uj)>());
 }
 
 template <bool _IsPh, class _Ti, class _Uj>
@@ -191,7 +190,7 @@ struct __bind_return<_Fp, const tuple<_BoundArgs...>, _TupleUj, true> {
 
 template <class _Fp, class _BoundArgs, size_t... _Indx, class _Args>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fp, _BoundArgs, _Args>::type
-__apply_functor(_Fp& __f, _BoundArgs& __bound_args, __tuple_indices<_Indx...>, _Args&& __args) {
+__apply_functor(_Fp& __f, _BoundArgs& __bound_args, __index_sequence<_Indx...>, _Args&& __args) {
   return std::__invoke(__f, std::__mu(std::get<_Indx>(__bound_args), __args)...);
 }
 
@@ -205,8 +204,6 @@ class __bind : public __weak_result_type<__decay_t<_Fp> > {
   _Fd __f_;
   _Td __bound_args_;
 
-  typedef typename __make_tuple_indices<sizeof...(_BoundArgs)>::type __indices;
-
 public:
   template <
       class _Gp,
@@ -219,14 +216,22 @@ class __bind : public __weak_result_type<__decay_t<_Fp> > {
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
   operator()(_Args&&... __args) {
-    return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
+    return std::__apply_functor(
+        __f_,
+        __bound_args_,
+        __make_index_sequence<sizeof...(_BoundArgs)>(),
+        tuple<_Args&&...>(std::forward<_Args>(__args)...));
   }
 
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
   typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type
   operator()(_Args&&... __args) const {
-    return std::__apply_functor(__f_, __bound_args_, __indices(), tuple<_Args&&...>(std::forward<_Args>(__args)...));
+    return std::__apply_functor(
+        __f_,
+        __bound_args_,
+        __make_index_sequence<sizeof...(_BoundArgs)>(),
+        tuple<_Args&&...>(std::forward<_Args>(__args)...));
   }
 };
 
diff --git a/libcxx/include/__memory_resource/polymorphic_allocator.h b/libcxx/include/__memory_resource/polymorphic_allocator.h
index 1b8711f10811d..6e7a9afc25deb 100644
--- a/libcxx/include/__memory_resource/polymorphic_allocator.h
+++ b/libcxx/include/__memory_resource/polymorphic_allocator.h
@@ -135,10 +135,10 @@ class _LIBCPP_AVAILABILITY_PMR polymorphic_allocator {
         piecewise_construct,
         __transform_tuple(typename __uses_alloc_ctor< _T1, polymorphic_allocator&, _Args1... >::type(),
                           std::move(__x),
-                          typename __make_tuple_indices<sizeof...(_Args1)>::type{}),
+                          make_index_sequence<sizeof...(_Args1)>()),
         __transform_tuple(typename __uses_alloc_ctor< _T2, polymorphic_allocator&, _Args2... >::type(),
                           std::move(__y),
-                          typename __make_tuple_indices<sizeof...(_Args2)>::type{}));
+                          make_index_sequence<sizeof...(_Args2)>()));
   }
 
   template <class _T1, class _T2>
@@ -194,20 +194,20 @@ class _LIBCPP_AVAILABILITY_PMR polymorphic_allocator {
 private:
   template <class... _Args, size_t... _Is>
   _LIBCPP_HIDE_FROM_ABI tuple<_Args&&...>
-  __transform_tuple(integral_constant<int, 0>, tuple<_Args...>&& __t, __tuple_indices<_Is...>) {
+  __transform_tuple(integral_constant<int, 0>, tuple<_Args...>&& __t, index_sequence<_Is...>) {
     return std::forward_as_tuple(std::get<_Is>(std::move(__t))...);
   }
 
   template <class... _Args, size_t... _Is>
   _LIBCPP_HIDE_FROM_ABI tuple<allocator_arg_t const&, polymorphic_allocator&, _Args&&...>
-  __transform_tuple(integral_constant<int, 1>, tuple<_Args...>&& __t, __tuple_indices<_Is...>) {
+  __transform_tuple(integral_constant<int, 1>, tuple<_Args...>&& __t, index_sequence<_Is...>) {
     using _Tup = tuple<allocator_arg_t const&, polymorphic_allocator&, _Args&&...>;
     return _Tup(allocator_arg, *this, std::get<_Is>(std::move(__t))...);
   }
 
   template <class... _Args, size_t... _Is>
   _LIBCPP_HIDE_FROM_ABI tuple<_Args&&..., polymorphic_allocator&>
-  __transform_tuple(integral_constant<int, 2>, tuple<_Args...>&& __t, __tuple_indices<_Is...>) {
+  __transform_tuple(integral_constant<int, 2>, tuple<_Args...>&& __t, index_sequence<_Is...>) {
     using _Tup = tuple<_Args&&..., polymorphic_allocator&>;
     return _Tup(std::get<_Is>(std::move(__t))..., *this);
   }
diff --git a/libcxx/include/__mutex/once_flag.h b/libcxx/include/__mutex/once_flag.h
index 33064499550eb..e384c15a9f9b6 100644
--- a/libcxx/include/__mutex/once_flag.h
+++ b/libcxx/include/__mutex/once_flag.h
@@ -13,9 +13,9 @@
 #include <__functional/invoke.h>
 #include <__memory/addressof.h>
 #include <__memory/shared_count.h> // __libcpp_acquire_load
-#include <__tuple/tuple_indices.h>
 #include <__tuple/tuple_size.h>
 #include <__utility/forward.h>
+#include <__utility/integer_sequence.h>
 #include <__utility/move.h>
 #include <cstdint>
 #ifndef _LIBCPP_CXX03_LANG
@@ -87,15 +87,12 @@ class __call_once_param {
 public:
   _LIBCPP_HIDE_FROM_ABI explicit __call_once_param(_Fp& __f) : __f_(__f) {}
 
-  _LIBCPP_HIDE_FROM_ABI void operator()() {
-    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 1>::type _Index;
-    __execute(_Index());
-  }
+  _LIBCPP_HIDE_FROM_ABI void operator()() { __execute(__make_index_sequence<tuple_size<_Fp>::value>()); }
 
 private:
   template <size_t... _Indices>
-  _LIBCPP_HIDE_FROM_ABI void __execute(__tuple_indices<_Indices...>) {
-    std::__invoke(std::get<0>(std::move(__f_)), std::get<_Indices>(std::move(__f_))...);
+  _LIBCPP_HIDE_FROM_ABI void __execute(__index_sequence<_Indices...>) {
+    std::__invoke(std::get<_Indices>(std::move(__f_))...);
   }
 };
 
diff --git a/libcxx/include/__thread/thread.h b/libcxx/include/__thread/thread.h
index 1b51571ce302e..a3b672bc0f0e7 100644
--- a/libcxx/include/__thread/thread.h
+++ b/libcxx/include/__thread/thread.h
@@ -155,8 +155,8 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id) {
 #  ifndef _LIBCPP_CXX03_LANG
 
 template <class _TSp, class _Fp, class... _Args, size_t... _Indices>
-inline _LIBCPP_HIDE_FROM_ABI void __thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>) {
-  std::__invoke(std::move(std::get<1>(__t)), std::move(std::get<_Indices>(__t))...);
+inline _LIBCPP_HIDE_FROM_ABI void __thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __index_sequence<_Indices...>) {
+  std::__invoke(std::move(std::get<_Indices + 1>(__t))...);
 }
 
 template <class _Fp>
@@ -164,8 +164,7 @@ _LIBCPP_HIDE_FROM_ABI void* __thread_proxy(void* __vp) {
   // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
   unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
   __thread_local_data().set_pointer(std::get<0>(*__p.get()).release());
-  typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
-  std::__thread_execute(*__p.get(), _Index());
+  std::__thread_execute(*__p.get(), __make_index_sequence<tuple_size<_Fp>::value - 1>());
   return nullptr;
 }
 
diff --git a/libcxx/include/__tuple/make_tuple_types.h b/libcxx/include/__tuple/make_tuple_types.h
index a5c9bcf23a6eb..3c22ec85dc9c7 100644
--- a/libcxx/include/__tuple/make_tuple_types.h
+++ b/libcxx/include/__tuple/make_tuple_types.h
@@ -14,12 +14,12 @@
 #include <__fwd/array.h>
 #include <__fwd/tuple.h>
 #include <__tuple/tuple_element.h>
-#include <__tuple/tuple_indices.h>
 #include <__tuple/tuple_size.h>
 #include <__tuple/tuple_types.h>
 #include <__type_traits/copy_cvref.h>
 #include <__type_traits/remove_cvref.h>
 #include <__type_traits/remove_reference.h>
+#include <__utility/integer_sequence.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -38,38 +38,35 @@ template <class _TupleTypes, class _TupleIndices>
 struct __make_tuple_types_flat;
 
 template <template <class...> class _Tuple, class... _Types, size_t... _Idx>
-struct __make_tuple_types_flat<_Tuple<_Types...>, __tuple_indices<_Idx...>> {
+struct __make_tuple_types_flat<_Tuple<_Types...>, __index_sequence<_Idx...>> {
   // Specialization for pair, tuple, and __tuple_types
   template <class _Tp>
   using __apply_quals _LIBCPP_NODEBUG = __tuple_types<__copy_cvref_t<_Tp, __type_pack_element<_Idx, _Types...>>...>;
 };
 
 template <class _Vt, size_t _Np, size_t... _Idx>
-struct __make_tuple_types_flat<array<_Vt, _Np>, __tuple_indices<_Idx...>> {
+struct __make_tuple_types_flat<array<_Vt, _Np>, __index_sequence<_Idx...>> {
   template <size_t>
   using __value_type _LIBCPP_NODEBUG = _Vt;
   template <class _Tp>
   using __apply_quals _LIBCPP_NODEBUG = __tuple_types<__copy_cvref_t<_Tp, __value_type<_Idx>>...>;
 };
 
-template <class _Tp,
-          size_t _Ep     = tuple_size<__libcpp_remove_reference_t<_Tp> >::value,
-          size_t _Sp     = 0,
-          bool _SameSize = (_Ep == tuple_size<__libcpp_remove_reference_t<_Tp> >::value)>
+template <class _Tp>
 struct __make_tuple_types {
-  static_assert(_Sp <= _Ep, "__make_tuple_types input error");
   using _RawTp _LIBCPP_NODEBUG = __remove_cvref_t<_Tp>;
-  using _Maker _LIBCPP_NODEBUG = __make_tuple_types_flat<_RawTp, typename __make_tuple_indices<_Ep, _Sp>::type>;
-  using type _LIBCPP_NODEBUG   = typename _Maker::template __apply_quals<_Tp>;
+  using _Maker _LIBCPP_NODEBUG =
+      __make_tuple_types_flat<_RawTp, __make_index_sequence<tuple_size<__libcpp_remove_reference_t<_Tp>>::value>>;
+  using type _LIBCPP_NODEBUG = typename _Maker::template __apply_quals<_Tp>;
 };
 
-template <class... _Types, size_t _Ep>
-struct __make_tuple_types<tuple<_Types...>, _Ep, 0, true> {
+template <class... _Types>
+struct __make_tuple_types<tuple<_Types...>> {
   using type _LIBCPP_NODEBUG = __tuple_types<_Types...>;
 };
 
-template <class... _Types, size_t _Ep>
-struct __make_tuple_types<__tuple_types<_Types...>, _Ep, 0, true> {
+template <class... _Types>
+struct __make_tuple_types<__tuple_types<_Types...>> {
   using type _LIBCPP_NODEBUG = __tuple_types<_Types...>;
 };
 
diff --git a/libcxx/include/__tuple/tuple_element.h b/libcxx/include/__tuple/tuple_element.h
index f67c8674644c3..607ac3a453de5 100644
--- a/libcxx/include/__tuple/tuple_element.h
+++ b/libcxx/include/__tuple/tuple_element.h
@@ -11,7 +11,6 @@
 
 #include <__config>
 #include <__cstddef/size_t.h>
-#include <__tuple/tuple_indices.h>
 #include <__tuple/tuple_types.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__tuple/tuple_indices.h b/libcxx/include/__tuple/tuple_indices.h
deleted file mode 100644
index 25dc9ec685916..0000000000000
--- a/libcxx/include/__tuple/tuple_indices.h
+++ /dev/null
@@ -1,37 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP___TUPLE_MAKE_TUPLE_INDICES_H
-#define _LIBCPP___TUPLE_MAKE_TUPLE_INDICES_H
-
-#include <__config>
-#include <__cstddef/size_t.h>
-#include <__utility/integer_sequence.h>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
-
-#ifndef _LIBCPP_CXX03_LANG
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <size_t...>
-struct __tuple_indices {};
-
-template <size_t _Ep, size_t _Sp = 0>
-struct __make_tuple_indices {
-  static_assert(_Sp <= _Ep, "__make_tuple_indices input error");
-  typedef __make_indices_imp<_Ep, _Sp> type;
-};
-
-_LIBCPP_END_NAMESPACE_STD
-
-#endif // _LIBCPP_CXX03_LANG
-
-#endif // _LIBCPP___TUPLE_MAKE_TUPLE_INDICES_H
diff --git a/libcxx/include/__utility/integer_sequence.h b/libcxx/include/__utility/integer_sequence.h
index d1c6e53c72131..329826ae5eda2 100644
--- a/libcxx/include/__utility/integer_sequence.h
+++ b/libcxx/include/__utility/integer_sequence.h
@@ -17,57 +17,41 @@
 #  pragma GCC system_header
 #endif
 
+#ifndef _LIBCPP_CXX03_LANG
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <size_t...>
-struct __tuple_indices;
+#  if __has_builtin(__make_integer_seq)
+template <template <class _Tp, _Tp...> class _BaseType, class _Tp, _Tp _SequenceSize>
+using __make_integer_sequence_impl _LIBCPP_NODEBUG = __make_integer_seq<_BaseType, _Tp, _SequenceSize>;
+#  else
+template <template <class _Tp, _Tp...> class _BaseType, class _Tp, _Tp _SequenceSize>
+using __make_integer_sequence_impl _LIBCPP_NODEBUG = _BaseType<_Tp, __integer_pack(_SequenceSize)...>;
+#  endif
 
-template <class _IdxType, _IdxType... _Values>
+template <class _Tp, _Tp... _Indices>
 struct __integer_sequence {
-  template <template <class _OIdxType, _OIdxType...> class _ToIndexSeq, class _ToIndexType>
-  using __convert _LIBCPP_NODEBUG = _ToIndexSeq<_ToIndexType, _Values...>;
-
-  template <size_t _Sp>
-  using __to_tuple_indices _LIBCPP_NODEBUG = __tuple_indices<(_Values + _Sp)...>;
+  using value_type = _Tp;
+  static_assert(is_integral<_Tp>::value, "std::integer_sequence can only be instantiated with an integral type");
+  static _LIBCPP_HIDE_FROM_ABI constexpr size_t size() noexcept { return sizeof...(_Indices); }
 };
 
-#if __has_builtin(__make_integer_seq)
-template <size_t _Ep, size_t _Sp>
-using __make_indices_imp _LIBCPP_NODEBUG =
-    typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template __to_tuple_indices<_Sp>;
-#elif __has_builtin(__integer_pack)
-template <size_t _Ep, size_t _Sp>
-using __make_indices_imp _LIBCPP_NODEBUG =
-    typename __integer_sequence<size_t, __integer_pack(_Ep - _Sp)...>::template __to_tuple_indices<_Sp>;
-#else
-#  error "No known way to get an integer pack from the compiler"
-#endif
+template <size_t... _Indices>
+using __index_sequence _LIBCPP_NODEBUG = __integer_sequence<size_t, _Indices...>;
 
-#if _LIBCPP_STD_VER >= 14
+template <size_t _SequenceSize>
+using __make_index_sequence _LIBCPP_NODEBUG = __make_integer_sequence_impl<__integer_sequence, size_t, _SequenceSize>;
 
-template <class _Tp, _Tp... _Ip>
-struct integer_sequence {
-  typedef _Tp value_type;
-  static_assert(is_integral<_Tp>::value, "std::integer_sequence can only be instantiated with an integral type");
-  static _LIBCPP_HIDE_FROM_ABI constexpr size_t size() noexcept { return sizeof...(_Ip); }
-};
+#  if _LIBCPP_STD_VER >= 14
+
+template <class _Tp, _Tp... _Indices>
+struct integer_sequence : __integer_sequence<_Tp, _Indices...> {};
 
 template <size_t... _Ip>
 using index_sequence = integer_sequence<size_t, _Ip...>;
 
-#  if __has_builtin(__make_integer_seq)
-
 template <class _Tp, _Tp _Ep>
-using make_integer_sequence _LIBCPP_NODEBUG = __make_integer_seq<integer_sequence, _Tp, _Ep>;
-
-#  elif __has_builtin(__integer_pack)
-
-template <class _Tp, _Tp _SequenceSize>
-using make_integer_sequence _LIBCPP_NODEBUG = integer_sequence<_Tp, __integer_pack(_SequenceSize)...>;
-
-#  else
-#    error "No known way to get an integer pack from the compiler"
-#  endif
+using make_integer_sequence _LIBCPP_NODEBUG = __make_integer_sequence_impl<integer_sequence, _Tp, _Ep>;
 
 template <size_t _Np>
 using make_index_sequence = make_integer_sequence<size_t, _Np>;
@@ -75,16 +59,18 @@ using make_index_sequence = make_integer_sequence<size_t, _Np>;
 template <class... _Tp>
 using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
 
-#  if _LIBCPP_STD_VER >= 20
+#    if _LIBCPP_STD_VER >= 20
 // Executes __func for every element in an index_sequence.
 template <size_t... _Index, class _Function>
 _LIBCPP_HIDE_FROM_ABI constexpr void __for_each_index_sequence(index_sequence<_Index...>, _Function __func) {
   (__func.template operator()<_Index>(), ...);
 }
-#  endif // _LIBCPP_STD_VER >= 20
+#    endif // _LIBCPP_STD_VER >= 20
 
-#endif // _LIBCPP_STD_VER >= 14
+#  endif // _LIBCPP_STD_VER >= 14
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_CXX03_LANG
+
 #endif // _LIBCPP___UTILITY_INTEGER_SEQUENCE_H
diff --git a/libcxx/include/__utility/pair.h b/libcxx/include/__utility/pair.h
index dbacbce044766..33694c52430f1 100644
--- a/libcxx/include/__utility/pair.h
+++ b/libcxx/include/__utility/pair.h
@@ -18,7 +18,6 @@
 #include <__fwd/array.h>
 #include <__fwd/pair.h>
 #include <__fwd/tuple.h>
-#include <__tuple/tuple_indices.h>
 #include <__tuple/tuple_like_no_subrange.h>
 #include <__tuple/tuple_size.h>
 #include <__type_traits/common_reference.h>
@@ -40,6 +39,7 @@
 #include <__type_traits/unwrap_ref.h>
 #include <__utility/declval.h>
 #include <__utility/forward.h>
+#include <__utility/integer_sequence.h>
 #include <__utility/move.h>
 #include <__utility/piecewise_construct.h>
 
@@ -225,8 +225,8 @@ struct pair
       : pair(__pc,
              __first_args,
              __second_args,
-             typename __make_tuple_indices<sizeof...(_Args1)>::type(),
-             typename __make_tuple_indices<sizeof...(_Args2) >::type()) {}
+             __make_index_sequence<sizeof...(_Args1)>(),
+             __make_index_sequence<sizeof...(_Args2)>()) {}
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair&
   operator=(__conditional_t<is_copy_assignable<first_type>::value && is_copy_assignable<second_type>::value,
@@ -440,8 +440,8 @@ struct pair
   pair(piecewise_construct_t,
        tuple<_Args1...>& __first_args,
        tuple<_Args2...>& __second_args,
-       __tuple_indices<_I1...>,
-       __tuple_indices<_I2...>)
+       __index_sequence<_I1...>,
+       __index_sequence<_I2...>)
       : first(std::forward<_Args1>(std::get<_I1>(__first_args))...),
         second(std::forward<_Args2>(std::get<_I2>(__second_args))...) {}
 #endif
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
index d109f27af58d6..e2b46154ae730 100644
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -147,7 +147,6 @@ template <size_t N> struct hash<std::bitset<N>>;
 #  include <__functional/hash.h>
 #  include <__functional/identity.h>
 #  include <__functional/unary_function.h>
-#  include <__tuple/tuple_indices.h>
 #  include <__type_traits/enable_if.h>
 #  include <__type_traits/integral_constant.h>
 #  include <__type_traits/is_char_like_type.h>
@@ -314,7 +313,7 @@ private:
   _LIBCPP_HIDE_FROM_ABI void __init(unsigned long long __v, true_type) _NOEXCEPT;
 #  else
   template <size_t... _Indices>
-  _LIBCPP_HIDE_FROM_ABI constexpr __bitset(unsigned long long __v, std::__tuple_indices<_Indices...>) _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI constexpr __bitset(unsigned long long __v, __index_sequence<_Indices...>) _NOEXCEPT
       : __first_{static_cast<__storage_type>(__v >> (_Indices * __bits_per_word))...} {}
 #  endif // _LIBCPP_CXX03_LANG
 };
@@ -352,10 +351,9 @@ template <size_t _N_words, size_t _Size>
 inline _LIBCPP_CONSTEXPR __bitset<_N_words, _Size>::__bitset(unsigned long long __v) _NOEXCEPT
 #  ifndef _LIBCPP_CXX03_LANG
     : __bitset(__v,
-               std::__make_indices_imp< (_N_words < (sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1)
-                                            ? _N_words
-                                            : (sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1,
-                                        0>{})
+               __make_index_sequence<(_N_words < (sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1)
+                                         ? _N_words
+                                         : (sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1>())
 #  endif
 {
 #  ifdef _LIBCPP_CXX03_LANG
diff --git a/libcxx/include/future b/libcxx/include/future
index abdd82dc95dd7..3df9dc9349a01 100644
--- a/libcxx/include/future
+++ b/libcxx/include/future
@@ -1842,15 +1842,12 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI __async_func(__async_func&& __f) : __f_(std::move(__f.__f_)) {}
 
-  _LIBCPP_HIDE_FROM_ABI _Rp operator()() {
-    typedef typename __make_tuple_indices<1 + sizeof...(_Args), 1>::type _Index;
-    return __execute(_Index());
-  }
+  _LIBCPP_HIDE_FROM_ABI _Rp operator()() { return __execute(__make_index_sequence<sizeof...(_Args) + 1>()); }
 
 private:
   template <size_t... _Indices>
-  _LIBCPP_HIDE_FROM_ABI _Rp __execute(__tuple_indices<_Indices...>) {
-    return std::__invoke(std::move(std::get<0>(__f_)), std::move(std::get<_Indices>(__f_))...);
+  _LIBCPP_HIDE_FROM_ABI _Rp __execute(__index_sequence<_Indices...>) {
+    return std::__invoke(std::move(std::get<_Indices>(__f_))...);
   }
 };
 
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 78607f2c1301d..0d2adbd56b6dd 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -2110,7 +2110,6 @@ module std [system] {
     module make_tuple_types         { header "__tuple/make_tuple_types.h" }
     module sfinae_helpers           { header "__tuple/sfinae_helpers.h" }
     module tuple_element            { header "__tuple/tuple_element.h" }
-    module tuple_indices            { header "__tuple/tuple_indices.h" }
     module tuple_like_ext           { header "__tuple/tuple_like_ext.h" }
     module tuple_like_no_subrange   { header "__tuple/tuple_like_no_subrange.h" }
     module tuple_like               { header "__tuple/tuple_like.h" }
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
index dc8e711f04878..78d8c8a9bcc6e 100644
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -469,17 +469,14 @@ public:
 
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI scoped_lock(adopt_lock_t, _MArgs&... __margs) : __t_(__margs...) {}
 
-  _LIBCPP_HIDE_FROM_ABI ~scoped_lock() {
-    typedef typename __make_tuple_indices<sizeof...(_MArgs)>::type _Indices;
-    __unlock_unpack(_Indices{}, __t_);
-  }
+  _LIBCPP_HIDE_FROM_ABI ~scoped_lock() { __unlock_unpack(make_index_sequence<sizeof...(_MArgs)>(), __t_); }
 
   scoped_lock(scoped_lock const&)            = delete;
   scoped_lock& operator=(scoped_lock const&) = delete;
 
 private:
   template <size_t... _Indx>
-  _LIBCPP_HIDE_FROM_ABI static void __unlock_unpack(__tuple_indices<_Indx...>, _MutexTuple& __mt) {
+  _LIBCPP_HIDE_FROM_ABI static void __unlock_unpack(index_sequence<_Indx...>, _MutexTuple& __mt) {
     (std::get<_Indx>(__mt).unlock(), ...);
   }
 
diff --git a/libcxx/include/scoped_allocator b/libcxx/include/scoped_allocator
index 7b8a9c9739ae0..74effc547f3e2 100644
--- a/libcxx/include/scoped_allocator
+++ b/libcxx/include/scoped_allocator
@@ -434,10 +434,10 @@ public:
         piecewise_construct,
         __transform_tuple(typename __uses_alloc_ctor< _T1, inner_allocator_type&, _Args1... >::type(),
                           std::move(__x),
-                          typename __make_tuple_indices<sizeof...(_Args1)>::type{}),
+                          __make_index_sequence<sizeof...(_Args1)>()),
         __transform_tuple(typename __uses_alloc_ctor< _T2, inner_allocator_type&, _Args2... >::type(),
                           std::move(__y),
-                          typename __make_tuple_indices<sizeof...(_Args2)>::type{}));
+                          __make_index_sequence<sizeof...(_Args2)>()));
   }
 
   template <class _T1, class _T2>
@@ -503,20 +503,20 @@ private:
 
   template <class... _Args, size_t... _Idx>
   _LIBCPP_HIDE_FROM_ABI tuple<_Args&&...>
-  __transform_tuple(integral_constant<int, 0>, tuple<_Args...>&& __t, __tuple_indices<_Idx...>) {
+  __transform_tuple(integral_constant<int, 0>, tuple<_Args...>&& __t, __index_sequence<_Idx...>) {
     return std::forward_as_tuple(std::get<_Idx>(std::move(__t))...);
   }
 
   template <class... _Args, size_t... _Idx>
   _LIBCPP_HIDE_FROM_ABI tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>
-  __transform_tuple(integral_constant<int, 1>, tuple<_Args...>&& __t, __tuple_indices<_Idx...>) {
+  __transform_tuple(integral_constant<int, 1>, tuple<_Args...>&& __t, __index_sequence<_Idx...>) {
     using _Tup = tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>;
     return _Tup(allocator_arg, inner_allocator(), std::get<_Idx>(std::move(__t))...);
   }
 
   template <class... _Args, size_t... _Idx>
   _LIBCPP_HIDE_FROM_ABI tuple<_Args&&..., inner_allocator_type&>
-  __transform_tuple(integral_constant<int, 2>, tuple<_Args...>&& __t, __tuple_indices<_Idx...>) {
+  __transform_tuple(integral_constant<int, 2>, tuple<_Args...>&& __t, __index_sequence<_Idx...>) {
     using _Tup = tuple<_Args&&..., inner_allocator_type&>;
     return _Tup(std::get<_Idx>(std::move(__t))..., inner_allocator());
   }
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index 75021f0ea51f6..662d926ed35a2 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -229,7 +229,6 @@ template <class... Types>
 #  include <__tuple/make_tuple_types.h>
 #  include <__tuple/sfinae_helpers.h>
 #  include <__tuple/tuple_element.h>
-#  include <__tuple/tuple_indices.h>
 #  include <__tuple/tuple_like_ext.h>
 #  include <__tuple/tuple_size.h>
 #  include <__tuple/tuple_types.h>
@@ -457,15 +456,15 @@ struct __tuple_impl;
 
 template <size_t... _Indx, class... _Tp>
 struct _LIBCPP_DECLSPEC_EMPTY_BASES
-    __tuple_impl<__tuple_indices<_Indx...>, _Tp...> : public __tuple_leaf<_Indx, _Tp>... {
+    __tuple_impl<__index_sequence<_Indx...>, _Tp...> : public __tuple_leaf<_Indx, _Tp>... {
   _LIBCPP_HIDE_FROM_ABI constexpr __tuple_impl() noexcept(
       __all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
 
   template <size_t... _Uf, class... _Tf, size_t... _Ul, class... _Tl, class... _Up>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(
-      __tuple_indices<_Uf...>,
+      __index_sequence<_Uf...>,
       __tuple_types<_Tf...>,
-      __tuple_indices<_Ul...>,
+      __index_sequence<_Ul...>,
       __tuple_types<_Tl...>,
       _Up&&... __u) noexcept(__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
                              __all<is_nothrow_default_constructible<_Tl>::value...>::value)
@@ -475,9 +474,9 @@ struct _LIBCPP_DECLSPEC_EMPTY_BASES
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(
       allocator_arg_t,
       const _Alloc& __a,
-      __tuple_indices<_Uf...>,
+      __index_sequence<_Uf...>,
       __tuple_types<_Tf...>,
-      __tuple_indices<_Ul...>,
+      __index_sequence<_Ul...>,
       __tuple_types<_Tl...>,
       _Up&&... __u)
       : __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a, std::forward<_Up>(__u))...,
@@ -518,19 +517,19 @@ struct _LIBCPP_DECLSPEC_EMPTY_BASES
 
 template <class _Dest, class _Source, size_t... _Np>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
-__memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {
+__memberwise_copy_assign(_Dest& __dest, _Source const& __source, __index_sequence<_Np...>) {
   std::__swallow(((std::get<_Np>(__dest) = std::get<_Np>(__source)), void(), 0)...);
 }
 
 template <class _Dest, class _Source, class... _Up, size_t... _Np>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
-__memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {
+__memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __index_sequence<_Np...>) {
   std::__swallow(((std::get<_Np>(__dest) = std::forward<_Up>(std::get<_Np>(__source))), void(), 0)...);
 }
 
 template <class... _Tp>
 class _LIBCPP_NO_SPECIALIZATIONS tuple {
-  typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;
+  typedef __tuple_impl<__make_index_sequence<sizeof...(_Tp)>, _Tp...> _BaseT;
 
   _BaseT __base_;
 
@@ -568,9 +567,9 @@ public:
       tuple(allocator_arg_t, _Alloc const& __a)
       : __base_(allocator_arg_t(),
                 __a,
-                __tuple_indices<>(),
+                __index_sequence<>(),
                 __tuple_types<>(),
-                typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
+                __make_index_sequence<sizeof...(_Tp)>(),
                 __tuple_types<_Tp...>()) {}
 
   // tuple(const T&...) constructors (including allocator_arg_t variants)
@@ -579,10 +578,10 @@ public:
   _LIBCPP_HIDE_FROM_ABI
   _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> >::value)
       tuple(const _Tp&... __t) noexcept(_And<is_nothrow_copy_constructible<_Tp>...>::value)
-      : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
-                typename __make_tuple_indices<0>::type(),
-                typename __make_tuple_types<tuple, 0>::type(),
+      : __base_(__make_index_sequence<sizeof...(_Tp)>(),
+                __tuple_types<_Tp...>(),
+                __index_sequence<>(),
+                __tuple_types<>(),
                 __t...) {}
 
   template <class _Alloc,
@@ -593,10 +592,10 @@ public:
       tuple(allocator_arg_t, const _Alloc& __a, const _Tp&... __t)
       : __base_(allocator_arg_t(),
                 __a,
-                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
-                typename __make_tuple_indices<0>::type(),
-                typename __make_tuple_types<tuple, 0>::type(),
+                __make_index_sequence<sizeof...(_Tp)>(),
+                __tuple_types<_Tp...>(),
+                __index_sequence<>(),
+                __tuple_types<>(),
                 __t...) {}
 
   // tuple(U&& ...) constructors (including allocator_arg_t variants)
@@ -616,10 +615,10 @@ public:
                            int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)
       tuple(_Up&&... __u) noexcept(_And<is_nothrow_constructible<_Tp, _Up>...>::value)
-      : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
-                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+      : __base_(__make_index_sequence<sizeof...(_Up)>(),
+                __tuple_types<_Tp...>(),
+                __index_sequence<>(),
+                __tuple_types<>(),
                 std::forward<_Up>(__u)...) {}
 
   template <class _Alloc,
@@ -630,10 +629,10 @@ public:
       tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
       : __base_(allocator_arg_t(),
                 __a,
-                typename __make_tuple_indices<sizeof...(_Up)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
-                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
-                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                __make_index_sequence<sizeof...(_Up)>(),
+                __tuple_types<_Tp...>(),
+                __index_sequence<>(),
+                __tuple_types<>(),
                 std::forward<_Up>(__u)...) {}
 
   // Copy and move constructors (including the allocator_arg_t variants)
@@ -838,7 +837,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
   operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple) noexcept(
       _And<is_nothrow_copy_assignable<_Tp>...>::value) {
-    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_copy_assign(*this, __tuple, __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -846,7 +845,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple const& __tuple) const
     requires(_And<is_copy_assignable<const _Tp>...>::value)
   {
-    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_copy_assign(*this, __tuple, __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -854,7 +853,7 @@ public:
     requires(_And<is_assignable<const _Tp&, _Tp>...>::value)
   {
     std::__memberwise_forward_assign(
-        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        *this, std::move(__tuple), __tuple_types<_Tp...>(), __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 #    endif // _LIBCPP_STD_VER >= 23
@@ -863,7 +862,7 @@ public:
   operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple) noexcept(
       _And<is_nothrow_move_assignable<_Tp>...>::value) {
     std::__memberwise_forward_assign(
-        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        *this, std::move(__tuple), __tuple_types<_Tp...>(), __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -873,7 +872,7 @@ public:
                      int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
   operator=(tuple<_Up...> const& __tuple) noexcept(_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value) {
-    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_copy_assign(*this, __tuple, __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -883,7 +882,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
   operator=(tuple<_Up...>&& __tuple) noexcept(_And<is_nothrow_assignable<_Tp&, _Up>...>::value) {
     std::__memberwise_forward_assign(
-        *this, std::move(__tuple), __tuple_types<_Up...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        *this, std::move(__tuple), __tuple_types<_Up...>(), __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -892,7 +891,7 @@ public:
             enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
                               is_assignable<const _Tp&, const _UTypes&>...>::value>* = nullptr>
   _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(const tuple<_UTypes...>& __u) const {
-    std::__memberwise_copy_assign(*this, __u, typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_copy_assign(*this, __u, __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -900,8 +899,7 @@ public:
             enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
                               is_assignable<const _Tp&, _UTypes>...>::value>* = nullptr>
   _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple<_UTypes...>&& __u) const {
-    std::__memberwise_forward_assign(
-        *this, __u, __tuple_types<_UTypes...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_forward_assign(*this, __u, __tuple_types<_UTypes...>(), __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 #    endif // _LIBCPP_STD_VER >= 23
@@ -967,7 +965,7 @@ public:
       __enable_if_t< _And< _BoolConstant<_Np == sizeof...(_Tp)>, is_assignable<_Tp&, _Up const&>... >::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
   operator=(array<_Up, _Np> const& __array) noexcept(_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value) {
-    std::__memberwise_copy_assign(*this, __array, typename __make_tuple_indices<sizeof...(_Tp)>::type());
+    std::__memberwise_copy_assign(*this, __array, __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -979,10 +977,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&
   operator=(array<_Up, _Np>&& __array) noexcept(_And<is_nothrow_assignable<_Tp&, _Up>...>::value) {
     std::__memberwise_forward_assign(
-        *this,
-        std::move(__array),
-        __tuple_types<_If<true, _Up, _Tp>...>(),
-        typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        *this, std::move(__array), __tuple_types<_If<true, _Up, _Tp>...>(), __make_index_sequence<sizeof...(_Tp)>());
     return *this;
   }
 
@@ -1291,17 +1286,17 @@ template <class _Rp, class _Indices, class _Tuple0, class... _Tuples>
 struct __tuple_cat_return_ref_imp;
 
 template <class... _Types, size_t... _I0, class _Tuple0>
-struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0> {
+struct __tuple_cat_return_ref_imp<tuple<_Types...>, __index_sequence<_I0...>, _Tuple0> {
   using _T0 _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tuple0>;
   typedef tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_I0, _T0>::type>&&...> type;
 };
 
 template <class... _Types, size_t... _I0, class _Tuple0, class _Tuple1, class... _Tuples>
-struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0, _Tuple1, _Tuples...>
+struct __tuple_cat_return_ref_imp<tuple<_Types...>, __index_sequence<_I0...>, _Tuple0, _Tuple1, _Tuples...>
     : public __tuple_cat_return_ref_imp<
           tuple<_Types...,
                 __copy_cvref_t<_Tuple0, typename tuple_element<_I0, __libcpp_remove_reference_t<_Tuple0>>::type>&&...>,
-          typename __make_tuple_indices<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>::type,
+          __make_index_sequence<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>,
           _Tuple1,
           _Tuples...> {};
 
@@ -1309,7 +1304,7 @@ template <class _Tuple0, class... _Tuples>
 struct __tuple_cat_return_ref
     : public __tuple_cat_return_ref_imp<
           tuple<>,
-          typename __make_tuple_indices< tuple_size<__libcpp_remove_reference_t<_Tuple0> >::value >::type,
+          __make_index_sequence< tuple_size<__libcpp_remove_reference_t<_Tuple0> >::value >,
           _Tuple0,
           _Tuples...> {};
 
@@ -1317,7 +1312,7 @@ template <class _Types, class _I0, class _J0>
 struct __tuple_cat;
 
 template <class... _Types, size_t... _I0, size_t... _J0>
-struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> > {
+struct __tuple_cat<tuple<_Types...>, __index_sequence<_I0...>, __index_sequence<_J0...>> {
   template <class _Tuple0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
   typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
@@ -1335,8 +1330,8 @@ struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J
     using _T0 _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tuple0>;
     using _T1 _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tuple1>;
     return __tuple_cat<tuple<_Types..., __copy_cvref_t<_Tuple0, typename tuple_element<_J0, _T0>::type>&&...>,
-                       typename __make_tuple_indices<sizeof...(_Types) + tuple_size<_T0>::value>::type,
-                       typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
+                       __make_index_sequence<sizeof...(_Types) + tuple_size<_T0>::value>,
+                       __make_index_sequence<tuple_size<_T1>::value>>()(
         std::forward_as_tuple(
             std::forward<_Types>(std::get<_I0>(__t))..., std::get<_J0>(std::forward<_Tuple0>(__t0))...),
         std::forward<_Tuple1>(__t1),
@@ -1346,7 +1341,7 @@ struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J
 
 template <class _TupleDst, class _TupleSrc, size_t... _Indices>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _TupleDst
-__tuple_cat_select_element_wise(_TupleSrc&& __src, __tuple_indices<_Indices...>) {
+__tuple_cat_select_element_wise(_TupleSrc&& __src, __index_sequence<_Indices...>) {
   static_assert(tuple_size<_TupleDst>::value == tuple_size<_TupleSrc>::value,
                 "misuse of __tuple_cat_select_element_wise with tuples of different sizes");
   return _TupleDst(std::get<_Indices>(std::forward<_TupleSrc>(__src))...);
@@ -1357,10 +1352,10 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename __tuple_cat_
 tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls) {
   using _T0 _LIBCPP_NODEBUG          = __libcpp_remove_reference_t<_Tuple0>;
   using _TRet _LIBCPP_NODEBUG        = typename __tuple_cat_return<_Tuple0, _Tuples...>::type;
-  using _T0Indices _LIBCPP_NODEBUG   = typename __make_tuple_indices<tuple_size<_T0>::value>::type;
-  using _TRetIndices _LIBCPP_NODEBUG = typename __make_tuple_indices<tuple_size<_TRet>::value>::type;
+  using _T0Indices _LIBCPP_NODEBUG   = __make_index_sequence<tuple_size<_T0>::value>;
+  using _TRetIndices _LIBCPP_NODEBUG = __make_index_sequence<tuple_size<_TRet>::value>;
   return std::__tuple_cat_select_element_wise<_TRet>(
-      __tuple_cat<tuple<>, __tuple_indices<>, _T0Indices>()(
+      __tuple_cat<tuple<>, __index_sequence<>, _T0Indices>()(
           tuple<>(), std::forward<_Tuple0>(__t0), std::forward<_Tuples>(__tpls)...),
       _TRetIndices());
 }
@@ -1376,7 +1371,7 @@ struct uses_allocator<tuple<_Tp...>, _Alloc> : true_type {};
 // clang-format off
 template <class _Fn, class _Tuple, size_t... _Id>
 inline _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto)
-__apply_tuple_impl(_Fn&& __f, _Tuple&& __t, __tuple_indices<_Id...>)
+__apply_tuple_impl(_Fn&& __f, _Tuple&& __t, index_sequence<_Id...>)
     _LIBCPP_NOEXCEPT_RETURN(std::__invoke(std::forward<_Fn>(__f), std::get<_Id>(std::forward<_Tuple>(__t))...))
 
 template <class _Fn, class _Tuple>
@@ -1384,28 +1379,28 @@ inline _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) apply(_Fn&& __f, _Tuple&&
     _LIBCPP_NOEXCEPT_RETURN(std::__apply_tuple_impl(
         std::forward<_Fn>(__f),
         std::forward<_Tuple>(__t),
-        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{}))
+        make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>()))
 
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>)
+inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>)
   noexcept(noexcept(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...)))
   requires is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...> {
   return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...);
 }
 #else
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>,
+inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...>> * = nullptr)
     _LIBCPP_NOEXCEPT_RETURN(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...))
 #endif // _LIBCPP_STD_VER >= 20
 
 template <class _Tp, class _Tuple,
-          class _Seq = typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type, class = void>
+          class _Seq = make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>, class = void>
 inline constexpr bool __can_make_from_tuple = false;
 
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>,
+inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, index_sequence<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::declval<_Tuple>()))...>>> = true;
 
 // Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9,
@@ -1420,7 +1415,7 @@ template <class _Tp, class _Tuple, class = enable_if_t<__can_make_from_tuple<_Tp
 #endif // _LIBCPP_STD_VER >= 20
 inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp make_from_tuple(_Tuple&& __t)
     _LIBCPP_NOEXCEPT_RETURN(std::__make_from_tuple_impl<_Tp>(
-        std::forward<_Tuple>(__t), typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{}))
+        std::forward<_Tuple>(__t), make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>()))
 #    undef _LIBCPP_NOEXCEPT_RETURN
 
 #  endif // _LIBCPP_STD_VER >= 17
diff --git a/libcxx/include/variant b/libcxx/include/variant
index ede9f486ecc2e..9beef146f203c 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -1127,14 +1127,14 @@ template <class _IdxSeq>
 struct __make_overloads_imp;
 
 template <size_t... _Idx>
-struct __make_overloads_imp<__tuple_indices<_Idx...> > {
+struct __make_overloads_imp<index_sequence<_Idx...> > {
   template <class... _Types>
   using _Apply _LIBCPP_NODEBUG = __all_overloads<__overload<_Types, _Idx>...>;
 };
 
 template <class... _Types>
 using _MakeOverloads _LIBCPP_NODEBUG =
-    typename __make_overloads_imp< __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>;
+    typename __make_overloads_imp<make_index_sequence<sizeof...(_Types)>>::template _Apply<_Types...>;
 
 template <class _Tp, class... _Types>
 using __best_match_t _LIBCPP_NODEBUG = typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type;
diff --git a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.apply/make_from_tuple.pass.cpp b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.apply/make_from_tuple.pass.cpp
index 34b79b38d2b95..2c14de8c796c1 100644
--- a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.apply/make_from_tuple.pass.cpp
+++ b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.apply/make_from_tuple.pass.cpp
@@ -214,7 +214,7 @@ static constexpr bool can_make_from_tuple =
 template <class T, class Tuple>
 auto test_make_from_tuple_impl(T&&, Tuple&& t)
     -> decltype(std::__make_from_tuple_impl<T>(
-                    t, typename std::__make_tuple_indices< std::tuple_size_v<std::remove_reference_t<Tuple>>>::type{}),
+                    t, typename std::make_index_sequence<std::tuple_size_v<std::remove_reference_t<Tuple>>>()),
                 std::uint8_t()) {
   return 0;
 }