1 //===-- declval utility -----------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_DECLVAL_H 9 #define LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_DECLVAL_H 10 11 #include "src/__support/CPP/type_traits/add_rvalue_reference.h" 12 #include "src/__support/CPP/type_traits/always_false.h" 13 14 namespace LIBC_NAMESPACE::cpp { 15 16 // declval declval()17template <typename T> cpp::add_rvalue_reference_t<T> declval() { 18 static_assert(cpp::always_false<T>, 19 "declval not allowed in an evaluated context"); 20 } 21 22 } // namespace LIBC_NAMESPACE::cpp 23 24 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_DECLVAL_H 25