[libcxx-commits] [libcxx] [libcxx][P1831R1] Deprecating volatile: library (PR #101439)

Louis Dionne via libcxx-commits libcxx-commits at lists.llvm.org
Thu Sep 5 08:05:31 PDT 2024


================
@@ -27,6 +27,34 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if _LIBCPP_STD_VER >= 20
+template <class _Tp, bool __lock_free>
+inline constexpr bool __deprecated_if_not_always_lock_free = true;
+
+template <class _Tp>
+[[deprecated("volatile atomic operations are deprecated when std::atomic<T>::is_always_lock_free is false")]]
+inline constexpr bool __deprecated_if_not_always_lock_free<_Tp, false> = true;
+
+// Many volatile overloads of of atomic<T> methods have a requirement to
+// guarantee atomic<T>::is_always_lock_free is truen in C++20.
----------------
ldionne wrote:

```suggestion
// guarantee atomic<T>::is_always_lock_free is true in C++20.
```

https://github.com/llvm/llvm-project/pull/101439


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