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//===----------------------------------------------------------------------===// 
// 
// 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___CONCEPTS_CONVERTIBLE_TO_H 
#define _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H 
 
#include <__config> 
#include <type_traits> 
 
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 
#pragma GCC system_header 
#endif 
 
_LIBCPP_BEGIN_NAMESPACE_STD 
 
#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS) 
 
// [concept.convertible] 
 
template<class _From, class _To> 
concept convertible_to = 
  is_convertible_v<_From, _To> && 
  requires (add_rvalue_reference_t<_From> (&__f)()) { 
    static_cast<_To>(__f()); 
  }; 
 
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS) 
 
_LIBCPP_END_NAMESPACE_STD 
 
#endif // _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H