1 //===-- None.h - Simple null value for implicit construction ------*- 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 // This file provides None, an enumerator for use in implicit constructors 10 // of various (usually templated) types to make such construction more 11 // terse. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_ADT_NONE_H 16 #define LLVM_ADT_NONE_H 17 18 namespace llvm { 19 /// A simple null object to allow implicit construction of Optional<T> 20 /// and similar types without having to spell out the specialization's name. 21 // (constant value 1 in an attempt to workaround MSVC build issue... ) 22 enum class NoneType { None = 1 }; 23 const NoneType None = NoneType::None; 24 } 25 26 #endif 27