Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/__functional/not_fn.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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___FUNCTIONAL_NOT_FN_H
+#define _LIBCPP___FUNCTIONAL_NOT_FN_H
+
+#include <__config>
+#include <__functional/invoke.h>
+#include <__functional/perfect_forward.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/is_constructible.h>
+#include <__type_traits/is_move_constructible.h>
+#include <__utility/forward.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 17
+
+struct __not_fn_op {
+    template <class... _Args>
+    _LIBCPP_HIDE_FROM_ABI
+    _LIBCPP_CONSTEXPR_SINCE_CXX20 auto operator()(_Args&&... __args) const
+        noexcept(noexcept(!_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
+        -> decltype(      !_VSTD::invoke(_VSTD::forward<_Args>(__args)...))
+        { return          !_VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
+};
+
+template <class _Fn>
+struct __not_fn_t : __perfect_forward<__not_fn_op, _Fn> {
+    using __perfect_forward<__not_fn_op, _Fn>::__perfect_forward;
+};
+
+template <class _Fn, class = enable_if_t<
+    is_constructible_v<decay_t<_Fn>, _Fn> &&
+    is_move_constructible_v<decay_t<_Fn>>
+>>
+_LIBCPP_HIDE_FROM_ABI
+_LIBCPP_CONSTEXPR_SINCE_CXX20 auto not_fn(_Fn&& __f) {
+    return __not_fn_t<decay_t<_Fn>>(_VSTD::forward<_Fn>(__f));
+}
+
+#endif // _LIBCPP_STD_VER >= 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FUNCTIONAL_NOT_FN_H