[libcxx-commits] [libcxx] [libcxx] Implementation of P1831R1 (PR #101439)

[Mark de Wever via libcxx-commits]

================
@@ -0,0 +1,107 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <atomic>
+
+// UNSUPPORTED: c++03, c++11, c++17
+
+#include <atomic>
+
+struct arr {
+  int x[32];
+  int y;
+
+  void method() {}
+};
+
+void f() {
+  std::memory_order ord = std::memory_order_relaxed;
+
+  int expected = 0, desired = 0;
+  std::atomic<int> i{};
+  i.operator=(0);
+  i.store(0, ord);
+  i.load(ord);
+  i.operator int();
+  i.exchange(0, ord);
+  i.compare_exchange_weak(expected, desired, ord);
+  i.compare_exchange_weak(expected, desired, ord, ord);
+  i.compare_exchange_strong(expected, desired, ord);
+  i.compare_exchange_strong(expected, desired, ord, ord);
+
+  volatile std::atomic<int> vi{};
+  vi.operator=(0);
+  vi.store(0, ord);
+  vi.load(ord);
+  vi.operator int();
+  vi.exchange(0, ord);
+  vi.compare_exchange_weak(expected, desired, ord);
+  vi.compare_exchange_weak(expected, desired, ord, ord);
+  vi.compare_exchange_strong(expected, desired, ord);
+  vi.compare_exchange_strong(expected, desired, ord, ord);
+
+  arr test_value;
+
+  volatile std::atomic<arr> va{};
+
+  // expected-warning at __atomic/atomic.h:* {{'__deprecated_if_not_awlays_lock_free<arr, false>' is deprecated: volatile atomic operations are deprecated when std::atomic<T>::is_always_lock_free is false}}
----------------
mordante wrote:

We typically don't care about the file generating the diagnostic. This makes it easier to refactor our headers without updating a lot of tests.
```suggestion
  // expected-warning@*:* {{'__deprecated_if_not_awlays_lock_free<arr, false>' is deprecated: volatile atomic operations are deprecated when std::atomic<T>::is_always_lock_free is false}}
```

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