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 | |
26 | namespace 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. |
31 | namespace cold_detail { |
32 | struct ColdClass { |
33 | FOLLY_COLD ColdClass() noexcept; |
34 | }; |
35 | } // namespace cold_detail |
36 | |
37 | /* using override */ using cold_detail::ColdClass; |
38 | } // namespace folly |
39 | |