[libcxx-commits] [libcxx] [libc++][ThreadSafety] Add thread safety annotations for variadic std::scoped_lock (PR #204462)

[Nikolas Klauser via libcxx-commits]

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@@ -469,25 +469,44 @@ public:
 };
 
 template <class... _MArgs>
+#      if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 2101
+class _LIBCPP_SCOPED_LOCKABLE scoped_lock {
+#      else
 class scoped_lock {
+#      endif
   static_assert(sizeof...(_MArgs) > 1, "At least 2 lock types required");
   typedef tuple<_MArgs&...> _MutexTuple;
 
 public:
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI explicit scoped_lock(_MArgs&... __margs) : __t_(__margs...) {
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI explicit scoped_lock(_MArgs&... __margs)
+#      if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 2101
+      _LIBCPP_ACQUIRE_CAPABILITY(__margs...)
+#      endif
+      : __t_(__margs...) {
     std::lock(__margs...);
   }
 
-  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI scoped_lock(adopt_lock_t, _MArgs&... __margs) : __t_(__margs...) {}
+  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI scoped_lock(adopt_lock_t, _MArgs&... __margs)
+#      if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 2101
+      _LIBCPP_REQUIRES_CAPABILITY(__margs...)
+#      endif
+      : __t_(__margs...) {
+  }
 
-  _LIBCPP_HIDE_FROM_ABI ~scoped_lock() { __unlock_unpack(make_index_sequence<sizeof...(_MArgs)>(), __t_); }
+#      if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 2101
+  _LIBCPP_RELEASE_CAPABILITY
+#      endif
+  _LIBCPP_HIDE_FROM_ABI ~scoped_lock() {
+    __unlock_unpack(make_index_sequence<sizeof...(_MArgs)>(), __t_);
+  }
 
   scoped_lock(scoped_lock const&)            = delete;
   scoped_lock& operator=(scoped_lock const&) = delete;
 
 private:
   template <size_t... _Indx>
-  _LIBCPP_HIDE_FROM_ABI static void __unlock_unpack(index_sequence<_Indx...>, _MutexTuple& __mt) {
+  _LIBCPP_NO_THREAD_SAFETY_ANALYSIS _LIBCPP_HIDE_FROM_ABI static void
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philnik777 wrote:

Why is this required? Can't we annotate this properly?

https://github.com/llvm/llvm-project/pull/204462