summaryrefslogtreecommitdiff
path: root/absl/flags/internal/flag_msvc.inc
diff options
context:
space:
mode:
Diffstat (limited to 'absl/flags/internal/flag_msvc.inc')
-rw-r--r--absl/flags/internal/flag_msvc.inc116
1 files changed, 0 insertions, 116 deletions
diff --git a/absl/flags/internal/flag_msvc.inc b/absl/flags/internal/flag_msvc.inc
deleted file mode 100644
index 614d09fd..00000000
--- a/absl/flags/internal/flag_msvc.inc
+++ /dev/null
@@ -1,116 +0,0 @@
-//
-// Copyright 2021 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Do not include this file directly.
-// Include absl/flags/flag.h instead.
-
-// MSVC debug builds do not implement initialization with constexpr constructors
-// correctly. To work around this we add a level of indirection, so that the
-// class `absl::Flag` contains an `internal::Flag*` (instead of being an alias
-// to that class) and dynamically allocates an instance when necessary. We also
-// forward all calls to internal::Flag methods via trampoline methods. In this
-// setup the `absl::Flag` class does not have constructor and virtual methods,
-// all the data members are public and thus MSVC is able to initialize it at
-// link time. To deal with multiple threads accessing the flag for the first
-// time concurrently we use an atomic boolean indicating if flag object is
-// initialized. We also employ the double-checked locking pattern where the
-// second level of protection is a global Mutex, so if two threads attempt to
-// construct the flag concurrently only one wins.
-//
-// This solution is based on a recommendation here:
-// https://developercommunity.visualstudio.com/content/problem/336946/class-with-constexpr-constructor-not-using-static.html?childToView=648454#comment-648454
-
-namespace flags_internal {
-absl::Mutex* GetGlobalConstructionGuard();
-} // namespace flags_internal
-
-// Public methods of `absl::Flag<T>` are NOT part of the Abseil Flags API.
-// See https://abseil.io/docs/cpp/guides/flags
-template <typename T>
-class Flag {
- public:
- // No constructor and destructor to ensure this is an aggregate type.
- // Visual Studio 2015 still requires the constructor for class to be
- // constexpr initializable.
-#if _MSC_VER <= 1900
- constexpr Flag(const char* name, const char* filename,
- const flags_internal::HelpGenFunc help_gen,
- const flags_internal::FlagDfltGenFunc default_value_gen)
- : name_(name),
- filename_(filename),
- help_gen_(help_gen),
- default_value_gen_(default_value_gen),
- inited_(false),
- impl_(nullptr) {}
-#endif
-
- flags_internal::Flag<T>& GetImpl() const {
- if (!inited_.load(std::memory_order_acquire)) {
- absl::MutexLock l(flags_internal::GetGlobalConstructionGuard());
-
- if (inited_.load(std::memory_order_acquire)) {
- return *impl_;
- }
-
- impl_ = new flags_internal::Flag<T>(
- name_, filename_,
- {flags_internal::FlagHelpMsg(help_gen_),
- flags_internal::FlagHelpKind::kGenFunc},
- {flags_internal::FlagDefaultSrc(default_value_gen_),
- flags_internal::FlagDefaultKind::kGenFunc});
- inited_.store(true, std::memory_order_release);
- }
-
- return *impl_;
- }
-
- // Public methods of `absl::Flag<T>` are NOT part of the Abseil Flags API.
- // See https://abseil.io/docs/cpp/guides/flags
- bool IsRetired() const { return GetImpl().IsRetired(); }
- absl::string_view Name() const { return GetImpl().Name(); }
- std::string Help() const { return GetImpl().Help(); }
- bool IsModified() const { return GetImpl().IsModified(); }
- bool IsSpecifiedOnCommandLine() const {
- return GetImpl().IsSpecifiedOnCommandLine();
- }
- std::string Filename() const { return GetImpl().Filename(); }
- std::string DefaultValue() const { return GetImpl().DefaultValue(); }
- std::string CurrentValue() const { return GetImpl().CurrentValue(); }
- template <typename U>
- inline bool IsOfType() const {
- return GetImpl().template IsOfType<U>();
- }
- T Get() const {
- return flags_internal::FlagImplPeer::InvokeGet<T>(GetImpl());
- }
- void Set(const T& v) {
- flags_internal::FlagImplPeer::InvokeSet(GetImpl(), v);
- }
- void InvokeCallback() { GetImpl().InvokeCallback(); }
-
- const CommandLineFlag& Reflect() const {
- return flags_internal::FlagImplPeer::InvokeReflect(GetImpl());
- }
-
- // The data members are logically private, but they need to be public for
- // this to be an aggregate type.
- const char* name_;
- const char* filename_;
- const flags_internal::HelpGenFunc help_gen_;
- const flags_internal::FlagDfltGenFunc default_value_gen_;
-
- mutable std::atomic<bool> inited_;
- mutable flags_internal::Flag<T>* impl_;
-};