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