1 // Copyright 2020 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 15 // Macros for using C++ features in older standards. 16 #pragma once 17 18 // Mark functions as constexpr if C++20 or newer 19 #if __cplusplus >= 202002L 20 #define PW_CONSTEXPR_CPP20 constexpr 21 #else 22 #define PW_CONSTEXPR_CPP20 23 #endif // __cpp_constexpr >= 201304L 24 25 // Mark functions as consteval if supported. 26 #if defined(__cpp_consteval) && __cpp_consteval >= 201811L 27 #define PW_CONSTEVAL consteval 28 #else 29 #define PW_CONSTEVAL constexpr 30 #endif // __cpp_consteval >= 201811L 31 32 // Mark functions as constinit if supported by the compiler. 33 #if defined(__cpp_constinit) && __cpp_constinit >= 201907L 34 #define PW_CONSTINIT constinit 35 #elif defined(__clang__) 36 #define PW_CONSTINIT [[clang::require_constant_initialization]] 37 #elif defined(__GNUC__) && __GNUC__ >= 13 38 #define PW_CONSTINIT __constinit 39 #else 40 #define PW_CONSTINIT 41 #endif // __cpp_constinit 42 43 // nodiscard with a string literal is only available in later versions (~C++20). 44 #if __cplusplus >= 202002L 45 #define PW_NODISCARD_STR(str) [[nodiscard(str)]] 46 #else 47 #define PW_NODISCARD_STR(str) [[nodiscard]] 48 #endif 49