1 //===-- convenient static_assert(false) helper ------------------*- 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 9 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_ALWAYS_FALSE_H 10 #define LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_ALWAYS_FALSE_H 11 12 #include "src/__support/macros/attributes.h" 13 #include "src/__support/macros/config.h" 14 15 namespace LIBC_NAMESPACE_DECL { 16 namespace cpp { 17 18 // This is technically not part of the standard but it come often enough that 19 // it's convenient to have around. 20 // 21 // https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2593r0.html#valid-workaround 22 // 23 // This will be fixed in C++23 according to [CWG 24 // 2518](https://cplusplus.github.io/CWG/issues/2518.html). 25 26 // Usage `static_assert(cpp::always_false<T>, "error message");` 27 template <typename...> LIBC_INLINE_VAR constexpr bool always_false = false; 28 29 } // namespace cpp 30 } // namespace LIBC_NAMESPACE_DECL 31 32 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_ALWAYS_FALSE_H 33