lib: establish Zircon libc++ and KTL foundation

27 files changed, 1197 insertions, 0 deletions

diff --git a/third_party/libcxx/include/c++/v1/__fwd/array.h b/third_party/libcxx/include/c++/v1/__fwd/array.h
new file mode 100644
index 0000000..476de88
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/array.h
@@ -0,0 +1,47 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_ARRAY_H
+#define _LIBCPP___FWD_ARRAY_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <__type_traits/integral_constant.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, size_t _Size>
+struct array;
+
+template <size_t _Ip, class _Tp, size_t _Size>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp& get(array<_Tp, _Size>&) _NOEXCEPT;
+
+template <size_t _Ip, class _Tp, size_t _Size>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp& get(const array<_Tp, _Size>&) _NOEXCEPT;
+
+#ifndef _LIBCPP_CXX03_LANG
+template <size_t _Ip, class _Tp, size_t _Size>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp&& get(array<_Tp, _Size>&&) _NOEXCEPT;
+
+template <size_t _Ip, class _Tp, size_t _Size>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Tp&& get(const array<_Tp, _Size>&&) _NOEXCEPT;
+#endif
+
+template <class _Tp>
+inline const bool __is_std_array_v = false;
+
+template <class _Tp, size_t _Size>
+inline const bool __is_std_array_v<array<_Tp, _Size> > = true;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_ARRAY_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/bit_reference.h b/third_party/libcxx/include/c++/v1/__fwd/bit_reference.h
new file mode 100644
index 0000000..36058d5
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/bit_reference.h
@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_BIT_REFERENCE_H
+#define _LIBCPP___FWD_BIT_REFERENCE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Cp, bool _IsConst, typename _Cp::__storage_type = 0>
+class __bit_iterator;
+
+template <class _Cp>
+struct __bit_array;
+
+template <class, class = void>
+struct __size_difference_type_traits;
+
+template <class _StoragePointer>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
+__fill_masked_range(_StoragePointer __word, unsigned __clz, unsigned __ctz, bool __fill_val);
+
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __trailing_mask(unsigned __clz);
+
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __leading_mask(unsigned __ctz);
+
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __middle_mask(unsigned __clz, unsigned __ctz);
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_BIT_REFERENCE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/byte.h b/third_party/libcxx/include/c++/v1/__fwd/byte.h
new file mode 100644
index 0000000..6f2d6ae
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/byte.h
@@ -0,0 +1,26 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_BYTE_H
+#define _LIBCPP___FWD_BYTE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 17
+_LIBCPP_BEGIN_UNVERSIONED_NAMESPACE_STD
+
+enum class byte : unsigned char;
+
+_LIBCPP_END_UNVERSIONED_NAMESPACE_STD
+#endif // _LIBCPP_STD_VER >= 17
+
+#endif // _LIBCPP___FWD_BYTE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/complex.h b/third_party/libcxx/include/c++/v1/__fwd/complex.h
new file mode 100644
index 0000000..ff3c5c1
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/complex.h
@@ -0,0 +1,42 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_COMPLEX_H
+#define _LIBCPP___FWD_COMPLEX_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp>
+class complex;
+
+#if _LIBCPP_STD_VER >= 26
+
+template <size_t _Ip, class _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp& get(complex<_Tp>&) noexcept;
+
+template <size_t _Ip, class _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp&& get(complex<_Tp>&&) noexcept;
+
+template <size_t _Ip, class _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr const _Tp& get(const complex<_Tp>&) noexcept;
+
+template <size_t _Ip, class _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& get(const complex<_Tp>&&) noexcept;
+
+#endif // _LIBCPP_STD_VER >= 26
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_COMPLEX_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/deque.h b/third_party/libcxx/include/c++/v1/__fwd/deque.h
new file mode 100644
index 0000000..35877a7
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/deque.h
@@ -0,0 +1,26 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_DEQUE_H
+#define _LIBCPP___FWD_DEQUE_H
+
+#include <__config>
+#include <__fwd/memory.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Allocator = allocator<_Tp> >
+class deque;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_DEQUE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/format.h b/third_party/libcxx/include/c++/v1/__fwd/format.h
new file mode 100644
index 0000000..e9d1536
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/format.h
@@ -0,0 +1,55 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_FORMAT_H
+#define _LIBCPP___FWD_FORMAT_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <class _Context>
+class basic_format_arg;
+
+template <class _OutIt, class _CharT>
+class basic_format_context;
+
+template <class _Tp, class _CharT = char>
+struct formatter;
+
+#  if _LIBCPP_STD_VER >= 23
+
+_LIBCPP_DIAGNOSTIC_PUSH
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wshadow")
+_LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wshadow")
+// This shadows map, set, and string.
+enum class range_format { disabled, map, set, sequence, string, debug_string };
+_LIBCPP_DIAGNOSTIC_POP
+
+template <class _Rp>
+constexpr range_format format_kind = [] {
+  // [format.range.fmtkind]/1
+  // A program that instantiates the primary template of format_kind is ill-formed.
+  static_assert(sizeof(_Rp) != sizeof(_Rp), "create a template specialization of format_kind for your type");
+  return range_format::disabled;
+}();
+
+#  endif // _LIBCPP_STD_VER >= 23
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_FORMAT_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/fstream.h b/third_party/libcxx/include/c++/v1/__fwd/fstream.h
new file mode 100644
index 0000000..34a14df
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/fstream.h
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_FSTREAM_H
+#define _LIBCPP___FWD_FSTREAM_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_filebuf;
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_ifstream;
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_ofstream;
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_fstream;
+
+using filebuf  = basic_filebuf<char>;
+using ifstream = basic_ifstream<char>;
+using ofstream = basic_ofstream<char>;
+using fstream  = basic_fstream<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wfilebuf  = basic_filebuf<wchar_t>;
+using wifstream = basic_ifstream<wchar_t>;
+using wofstream = basic_ofstream<wchar_t>;
+using wfstream  = basic_fstream<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(filebuf) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wfilebuf)) basic_filebuf;
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(ifstream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wifstream)) basic_ifstream;
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(ofstream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wofstream)) basic_ofstream;
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(fstream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wfstream)) basic_fstream;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_FSTREAM_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/functional.h b/third_party/libcxx/include/c++/v1/__fwd/functional.h
new file mode 100644
index 0000000..a8c6024
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/functional.h
@@ -0,0 +1,35 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_FUNCTIONAL_H
+#define _LIBCPP___FWD_FUNCTIONAL_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 14
+template <class _Tp = void>
+#else
+template <class _Tp>
+#endif
+struct less;
+
+template <class>
+struct hash;
+
+template <class>
+class reference_wrapper;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_FUNCTIONAL_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/get.h b/third_party/libcxx/include/c++/v1/__fwd/get.h
new file mode 100644
index 0000000..6121ed0
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/get.h
@@ -0,0 +1,24 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_GET_H
+#define _LIBCPP___FWD_GET_H
+
+#include <__config>
+#include <__fwd/array.h>
+#include <__fwd/complex.h>
+#include <__fwd/pair.h>
+#include <__fwd/subrange.h>
+#include <__fwd/tuple.h>
+#include <__fwd/variant.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#endif // _LIBCPP___FWD_GET_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/ios.h b/third_party/libcxx/include/c++/v1/__fwd/ios.h
new file mode 100644
index 0000000..fd6738a
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/ios.h
@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_IOS_H
+#define _LIBCPP___FWD_IOS_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+class _LIBCPP_EXPORTED_FROM_ABI ios_base;
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_ios;
+
+using ios = basic_ios<char>;
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wios = basic_ios<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(ios) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wios)) basic_ios;
+
+#if _LIBCPP_LIBC_NEWLIB
+// On newlib, off_t is 'long int'
+using streamoff = long int; // for char_traits in <string>
+#else
+using streamoff = long long; // for char_traits in <string>
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_IOS_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/istream.h b/third_party/libcxx/include/c++/v1/__fwd/istream.h
new file mode 100644
index 0000000..91c21c1
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/istream.h
@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_ISTREAM_H
+#define _LIBCPP___FWD_ISTREAM_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_istream;
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_iostream;
+
+using istream  = basic_istream<char>;
+using iostream = basic_iostream<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wistream  = basic_istream<wchar_t>;
+using wiostream = basic_iostream<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(istream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wistream)) basic_istream;
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(iostream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wiostream)) basic_iostream;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_ISTREAM_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/mdspan.h b/third_party/libcxx/include/c++/v1/__fwd/mdspan.h
new file mode 100644
index 0000000..8889567
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/mdspan.h
@@ -0,0 +1,57 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___MDSPAN_LAYOUTS_H
+#define _LIBCPP___MDSPAN_LAYOUTS_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+// Layout policy with a mapping which corresponds to FORTRAN-style array layouts
+struct layout_left {
+  template <class _Extents>
+  class mapping;
+};
+
+// Layout policy with a mapping which corresponds to C-style array layouts
+struct layout_right {
+  template <class _Extents>
+  class mapping;
+};
+
+// Layout policy with a unique mapping where strides are arbitrary
+struct layout_stride {
+  template <class _Extents>
+  class mapping;
+};
+
+#endif // _LIBCPP_STD_VER >= 23
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___MDSPAN_LAYOUTS_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/memory.h b/third_party/libcxx/include/c++/v1/__fwd/memory.h
new file mode 100644
index 0000000..09ab5d8
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/memory.h
@@ -0,0 +1,28 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_MEMORY_H
+#define _LIBCPP___FWD_MEMORY_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp>
+class allocator;
+
+template <class _Tp>
+class shared_ptr;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_MEMORY_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/memory_resource.h b/third_party/libcxx/include/c++/v1/__fwd/memory_resource.h
new file mode 100644
index 0000000..dc5a7cc
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/memory_resource.h
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_MEMORY_RESOURCE_H
+#define _LIBCPP___FWD_MEMORY_RESOURCE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace pmr {
+template <class _ValueType>
+class _LIBCPP_AVAILABILITY_PMR polymorphic_allocator;
+} // namespace pmr
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 17
+
+#endif // _LIBCPP___FWD_MEMORY_RESOURCE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/ostream.h b/third_party/libcxx/include/c++/v1/__fwd/ostream.h
new file mode 100644
index 0000000..9ceb02d
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/ostream.h
@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_OSTREAM_H
+#define _LIBCPP___FWD_OSTREAM_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_ostream;
+
+using ostream = basic_ostream<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wostream = basic_ostream<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(ostream) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wostream)) basic_ostream;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_OSTREAM_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/pair.h b/third_party/libcxx/include/c++/v1/__fwd/pair.h
new file mode 100644
index 0000000..cf07eab
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/pair.h
@@ -0,0 +1,51 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_PAIR_H
+#define _LIBCPP___FWD_PAIR_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <__fwd/tuple.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class, class>
+struct pair;
+
+template <class _Type>
+inline const bool __is_pair_v = false;
+
+template <class _Type1, class _Type2>
+inline const bool __is_pair_v<pair<_Type1, _Type2> > = true;
+
+template <size_t _Ip, class _T1, class _T2>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, pair<_T1, _T2> >::type&
+get(pair<_T1, _T2>&) _NOEXCEPT;
+
+template <size_t _Ip, class _T1, class _T2>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
+get(const pair<_T1, _T2>&) _NOEXCEPT;
+
+#ifndef _LIBCPP_CXX03_LANG
+template <size_t _Ip, class _T1, class _T2>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
+get(pair<_T1, _T2>&&) _NOEXCEPT;
+
+template <size_t _Ip, class _T1, class _T2>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
+get(const pair<_T1, _T2>&&) _NOEXCEPT;
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_PAIR_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/queue.h b/third_party/libcxx/include/c++/v1/__fwd/queue.h
new file mode 100644
index 0000000..d32730d
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/queue.h
@@ -0,0 +1,31 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_QUEUE_H
+#define _LIBCPP___FWD_QUEUE_H
+
+#include <__config>
+#include <__functional/operations.h>
+#include <__fwd/deque.h>
+#include <__fwd/vector.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Container = deque<_Tp> >
+class queue;
+
+template <class _Tp, class _Container = vector<_Tp>, class _Compare = less<typename _Container::value_type> >
+class priority_queue;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_QUEUE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/span.h b/third_party/libcxx/include/c++/v1/__fwd/span.h
new file mode 100644
index 0000000..5d473ee
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/span.h
@@ -0,0 +1,38 @@
+// -*- C++ -*-
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_SPAN_H
+#define _LIBCPP___FWD_SPAN_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max();
+template <typename _Tp, size_t _Extent = dynamic_extent>
+class span;
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___FWD_SPAN_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/sstream.h b/third_party/libcxx/include/c++/v1/__fwd/sstream.h
new file mode 100644
index 0000000..fe637d8
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/sstream.h
@@ -0,0 +1,58 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_SSTREAM_H
+#define _LIBCPP___FWD_SSTREAM_H
+
+#include <__config>
+#include <__fwd/memory.h>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
+class basic_stringbuf;
+
+template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
+class basic_istringstream;
+template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
+class basic_ostringstream;
+template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
+class basic_stringstream;
+
+using stringbuf     = basic_stringbuf<char>;
+using istringstream = basic_istringstream<char>;
+using ostringstream = basic_ostringstream<char>;
+using stringstream  = basic_stringstream<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wstringbuf     = basic_stringbuf<wchar_t>;
+using wistringstream = basic_istringstream<wchar_t>;
+using wostringstream = basic_ostringstream<wchar_t>;
+using wstringstream  = basic_stringstream<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_PREFERRED_NAME(stringbuf) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wstringbuf)) basic_stringbuf;
+template <class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_PREFERRED_NAME(istringstream)
+    _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wistringstream)) basic_istringstream;
+template <class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_PREFERRED_NAME(ostringstream)
+    _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wostringstream)) basic_ostringstream;
+template <class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_PREFERRED_NAME(stringstream)
+    _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wstringstream)) basic_stringstream;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_SSTREAM_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/stack.h b/third_party/libcxx/include/c++/v1/__fwd/stack.h
new file mode 100644
index 0000000..922f03e
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/stack.h
@@ -0,0 +1,26 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_STACK_H
+#define _LIBCPP___FWD_STACK_H
+
+#include <__config>
+#include <__fwd/deque.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Container = deque<_Tp> >
+class stack;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_STACK_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/streambuf.h b/third_party/libcxx/include/c++/v1/__fwd/streambuf.h
new file mode 100644
index 0000000..d3d9d46
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/streambuf.h
@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_STREAMBUF_H
+#define _LIBCPP___FWD_STREAMBUF_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_streambuf;
+
+using streambuf = basic_streambuf<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wstreambuf = basic_streambuf<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(streambuf) _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wstreambuf)) basic_streambuf;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_STREAMBUF_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/string.h b/third_party/libcxx/include/c++/v1/__fwd/string.h
new file mode 100644
index 0000000..254d0c8
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/string.h
@@ -0,0 +1,107 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___FWD_STRING_H
+#define _LIBCPP___FWD_STRING_H
+
+#include <__config>
+#include <__fwd/memory.h>
+#include <__fwd/memory_resource.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT>
+struct char_traits;
+template <>
+struct char_traits<char>;
+
+#if _LIBCPP_HAS_CHAR8_T
+template <>
+struct char_traits<char8_t>;
+#endif
+
+template <>
+struct char_traits<char16_t>;
+template <>
+struct char_traits<char32_t>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+template <>
+struct char_traits<wchar_t>;
+#endif
+
+template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
+class basic_string;
+
+using string = basic_string<char>;
+
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+using wstring = basic_string<wchar_t>;
+#endif
+
+#if _LIBCPP_HAS_CHAR8_T
+using u8string = basic_string<char8_t>;
+#endif
+
+using u16string = basic_string<char16_t>;
+using u32string = basic_string<char32_t>;
+
+#if _LIBCPP_STD_VER >= 17
+
+namespace pmr {
+template <class _CharT, class _Traits = char_traits<_CharT>>
+using basic_string _LIBCPP_AVAILABILITY_PMR = std::basic_string<_CharT, _Traits, polymorphic_allocator<_CharT>>;
+
+using string _LIBCPP_AVAILABILITY_PMR = basic_string<char>;
+
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
+using wstring _LIBCPP_AVAILABILITY_PMR = basic_string<wchar_t>;
+#  endif
+
+#  if _LIBCPP_HAS_CHAR8_T
+using u8string _LIBCPP_AVAILABILITY_PMR = basic_string<char8_t>;
+#  endif
+
+using u16string _LIBCPP_AVAILABILITY_PMR = basic_string<char16_t>;
+using u32string _LIBCPP_AVAILABILITY_PMR = basic_string<char32_t>;
+} // namespace pmr
+
+#endif // _LIBCPP_STD_VER >= 17
+
+// clang-format off
+template <class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_PREFERRED_NAME(string)
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+      _LIBCPP_PREFERRED_NAME(wstring)
+#endif
+#if _LIBCPP_HAS_CHAR8_T
+      _LIBCPP_PREFERRED_NAME(u8string)
+#endif
+      _LIBCPP_PREFERRED_NAME(u16string)
+      _LIBCPP_PREFERRED_NAME(u32string)
+#if _LIBCPP_STD_VER >= 17
+      _LIBCPP_PREFERRED_NAME(pmr::string)
+#  if _LIBCPP_HAS_WIDE_CHARACTERS
+      _LIBCPP_PREFERRED_NAME(pmr::wstring)
+#  endif
+#  if _LIBCPP_HAS_CHAR8_T
+      _LIBCPP_PREFERRED_NAME(pmr::u8string)
+#  endif
+      _LIBCPP_PREFERRED_NAME(pmr::u16string)
+      _LIBCPP_PREFERRED_NAME(pmr::u32string)
+#endif
+      basic_string;
+// clang-format on
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_STRING_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/string_view.h b/third_party/libcxx/include/c++/v1/__fwd/string_view.h
new file mode 100644
index 0000000..8da963d
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/string_view.h
@@ -0,0 +1,50 @@
+// -*- C++ -*-
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_STRING_VIEW_H
+#define _LIBCPP___FWD_STRING_VIEW_H
+
+#include <__config>
+#include <__fwd/string.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _CharT, class _Traits = char_traits<_CharT> >
+class basic_string_view;
+
+typedef basic_string_view<char> string_view;
+#if _LIBCPP_HAS_CHAR8_T
+typedef basic_string_view<char8_t> u8string_view;
+#endif
+typedef basic_string_view<char16_t> u16string_view;
+typedef basic_string_view<char32_t> u32string_view;
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+typedef basic_string_view<wchar_t> wstring_view;
+#endif
+
+// clang-format off
+template <class _CharT, class _Traits>
+class _LIBCPP_PREFERRED_NAME(string_view)
+#if _LIBCPP_HAS_WIDE_CHARACTERS
+      _LIBCPP_PREFERRED_NAME(wstring_view)
+#endif
+#if _LIBCPP_HAS_CHAR8_T
+      _LIBCPP_PREFERRED_NAME(u8string_view)
+#endif
+      _LIBCPP_PREFERRED_NAME(u16string_view)
+      _LIBCPP_PREFERRED_NAME(u32string_view)
+      basic_string_view;
+// clang-format on
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_STRING_VIEW_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/subrange.h b/third_party/libcxx/include/c++/v1/__fwd/subrange.h
new file mode 100644
index 0000000..81db94a
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/subrange.h
@@ -0,0 +1,49 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_SUBRANGE_H
+#define _LIBCPP___FWD_SUBRANGE_H
+
+#include <__concepts/copyable.h>
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <__iterator/concepts.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+enum class subrange_kind : bool { unsized, sized };
+
+template <input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent, subrange_kind _Kind>
+  requires(_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _Iter>)
+class subrange;
+
+template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
+  requires((_Index == 0 && copyable<_Iter>) || _Index == 1)
+_LIBCPP_HIDE_FROM_ABI constexpr auto get(const subrange<_Iter, _Sent, _Kind>&);
+
+template <size_t _Index, class _Iter, class _Sent, subrange_kind _Kind>
+  requires(_Index < 2)
+_LIBCPP_HIDE_FROM_ABI constexpr auto get(subrange<_Iter, _Sent, _Kind>&&);
+
+} // namespace ranges
+
+using ranges::get;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP___FWD_SUBRANGE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/tuple.h b/third_party/libcxx/include/c++/v1/__fwd/tuple.h
new file mode 100644
index 0000000..dc96c03
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/tuple.h
@@ -0,0 +1,66 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_TUPLE_H
+#define _LIBCPP___FWD_TUPLE_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <size_t, class>
+struct tuple_element;
+
+template <size_t _Np, class _Tp>
+using __tuple_element_t _LIBCPP_NODEBUG = typename tuple_element<_Np, _Tp>::type;
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <class...>
+class tuple;
+
+template <class>
+inline const bool __is_tuple_v = false;
+
+template <class... _Tp>
+inline const bool __is_tuple_v<tuple<_Tp...>> = true;
+
+template <size_t _Ip, class... _Tp>
+struct tuple_element<_Ip, tuple<_Tp...> > {
+  using type _LIBCPP_NODEBUG = __type_pack_element<_Ip, _Tp...>;
+};
+
+template <class>
+struct tuple_size;
+
+template <size_t _Ip, class... _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&
+get(tuple<_Tp...>&) _NOEXCEPT;
+
+template <size_t _Ip, class... _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&
+get(const tuple<_Tp...>&) _NOEXCEPT;
+
+template <size_t _Ip, class... _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&&
+get(tuple<_Tp...>&&) _NOEXCEPT;
+
+template <size_t _Ip, class... _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
+get(const tuple<_Tp...>&&) _NOEXCEPT;
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_TUPLE_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/variant.h b/third_party/libcxx/include/c++/v1/__fwd/variant.h
new file mode 100644
index 0000000..fef7071
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/variant.h
@@ -0,0 +1,68 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_VARIANT_H
+#define _LIBCPP___FWD_VARIANT_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 17
+
+template <class... _Types>
+class variant;
+
+template <class _Tp>
+struct variant_size;
+
+template <class _Tp>
+inline constexpr size_t variant_size_v = variant_size<_Tp>::value;
+
+template <size_t _Ip, class _Tp>
+struct variant_alternative;
+
+template <size_t _Ip, class _Tp>
+using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
+
+inline constexpr size_t variant_npos = static_cast<size_t>(-1);
+
+template <size_t _Ip, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(variant<_Types...>&);
+
+template <size_t _Ip, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(variant<_Types...>&&);
+
+template <size_t _Ip, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(const variant<_Types...>&);
+
+template <size_t _Ip, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(const variant<_Types...>&&);
+
+template <class _Tp, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp& get(variant<_Types...>&);
+
+template <class _Tp, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp&& get(variant<_Types...>&&);
+
+template <class _Tp, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr const _Tp& get(const variant<_Types...>&);
+
+template <class _Tp, class... _Types>
+_LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& get(const variant<_Types...>&&);
+
+#endif // _LIBCPP_STD_VER >= 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_VARIANT_H
diff --git a/third_party/libcxx/include/c++/v1/__fwd/vector.h b/third_party/libcxx/include/c++/v1/__fwd/vector.h
new file mode 100644
index 0000000..31084ec
--- /dev/null
+++ b/third_party/libcxx/include/c++/v1/__fwd/vector.h
@@ -0,0 +1,29 @@
+//===---------------------------------------------------------------------===//
+//
+// 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___FWD_VECTOR_H
+#define _LIBCPP___FWD_VECTOR_H
+
+#include <__config>
+#include <__fwd/memory.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, class _Alloc = allocator<_Tp> >
+class vector;
+
+template <class _Allocator>
+class vector<bool, _Allocator>;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FWD_VECTOR_H