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 #ifdef __cpp_inline_variables 19 #define PW_INLINE_VARIABLE inline 20 #else 21 #define PW_INLINE_VARIABLE 22 #endif // __cpp_inline_variables 23 24 // Mark functions as constexpr if C++20 or newer 25 #if __cplusplus >= 202002L 26 #define PW_CONSTEXPR_CPP20 constexpr 27 #else 28 #define PW_CONSTEXPR_CPP20 29 #endif // __cpp_constexpr >= 201304L 30 31 // Mark functions as consteval if supported. 32 #if defined(__cpp_consteval) && __cpp_consteval >= 201811L 33 #define PW_CONSTEVAL consteval 34 #else 35 #define PW_CONSTEVAL constexpr 36 #endif // __cpp_consteval >= 201811L 37 38 // Mark functions as constinit if supported by the compiler. 39 #if defined(__cpp_constinit) 40 #define PW_CONSTINIT constinit 41 #elif defined(__clang__) 42 #define PW_CONSTINIT [[clang::require_constant_initialization]] 43 #elif defined(__GNUC__) && __GNUC__ >= 10 44 #define PW_CONSTINIT __constinit 45 #else 46 #define PW_CONSTINIT 47 #endif // __cpp_constinit 48