1/*
2 * Copyright 2017-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* Tag any class as `cold` by inheriting from folly::cold::ColdClass
18 *
19 * Intended use: things like folly::Unexpected which are designed to only be
20 * instantiated on error paths.
21 */
22#pragma once
23
24#include <folly/CppAttributes.h>
25
26namespace folly {
27// ColdClass should be in its own namespace: inheriting from any class adds its
28// innermost namespace to the namespaces inspected during
29// argument-dependent-lookoup. We want people to be able to derive from this
30// without implicitly picking up the folly namespace for ADL on their classes.
31namespace cold_detail {
32struct ColdClass {
33 FOLLY_COLD ColdClass() noexcept;
34};
35} // namespace cold_detail
36
37/* using override */ using cold_detail::ColdClass;
38} // namespace folly
39