1 //
2 //  Copyright 2019 The Abseil Authors.
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 //      https://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 #include "absl/flags/flag.h"
17 
18 #include "absl/base/config.h"
19 
20 namespace absl {
21 ABSL_NAMESPACE_BEGIN
22 
23 // This global mutex protects on-demand construction of flag objects in MSVC
24 // builds.
25 #if defined(_MSC_VER) && !defined(__clang__)
26 
27 namespace flags_internal {
28 
29 ABSL_CONST_INIT static absl::Mutex construction_guard(absl::kConstInit);
30 
GetGlobalConstructionGuard()31 absl::Mutex* GetGlobalConstructionGuard() { return &construction_guard; }
32 
33 }  // namespace flags_internal
34 
35 #endif
36 
37 ABSL_NAMESPACE_END
38 }  // namespace absl
39