From 99c04cc73a225ffa493d37f0d584568b8fbc8a6d Mon Sep 17 00:00:00 2001
From: Shengxin Pei <TPPPP72@outlook.com>
Date: Thu, 20 Aug 2026 17:42:13 +0800
Subject: [PATCH 1/2] Deprecate volatile atomic increment, decrement, and
 wait/notify operations

---
 stl/inc/atomic                                | 11 ++++
 tests/std/test.lst                            |  1 +
 .../env.lst                                   |  4 ++
 .../test.cpp                                  | 50 +++++++++++++++++++
 4 files changed, 66 insertions(+)
 create mode 100644 tests/std/tests/P1831R1_deprecated_volatile_atomic/env.lst
 create mode 100644 tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp

diff --git a/stl/inc/atomic b/stl/inc/atomic
index 74e81813616..ecd01a238a2 100644
--- a/stl/inc/atomic
+++ b/stl/inc/atomic
@@ -1662,19 +1662,23 @@ struct _Atomic_integral_facade : _Atomic_integral<_Ty> {
 
     using _Base::operator++;
     _Ty operator++(int) volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator++(0);
     }
 
     _Ty operator++() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator++();
     }
 
     using _Base::operator--;
     _Ty operator--(int) volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator--(0);
     }
 
     _Ty operator--() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator--();
     }
 
@@ -1960,6 +1964,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator++(int) volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return fetch_add(1);
     }
 
@@ -1968,6 +1973,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator++() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return fetch_add(1) + 1;
     }
 
@@ -1976,6 +1982,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator--(int) volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return fetch_add(-1);
     }
 
@@ -1984,6 +1991,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator--() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         return fetch_add(-1) - 1;
     }
 
@@ -2242,16 +2250,19 @@ public:
 #if _HAS_CXX20
     using _Base::wait;
     void wait(const _Ty _Expected, const memory_order _Order = memory_order_seq_cst) const volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         const_cast<const atomic*>(this)->_Base::wait(_Expected, _Order);
     }
 
     using _Base::notify_one;
     void notify_one() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         const_cast<atomic*>(this)->_Base::notify_one();
     }
 
     using _Base::notify_all;
     void notify_all() volatile noexcept {
+        (void) _Deprecate_non_lock_free_volatile<_Ty>;
         const_cast<atomic*>(this)->_Base::notify_all();
     }
 #endif // _HAS_CXX20
diff --git a/tests/std/test.lst b/tests/std/test.lst
index cce97d793eb..c5204f5176c 100644
--- a/tests/std/test.lst
+++ b/tests/std/test.lst
@@ -640,6 +640,7 @@ tests\P1645R1_constexpr_numeric
 tests\P1659R3_ranges_alg_ends_with
 tests\P1659R3_ranges_alg_starts_with
 tests\P1682R3_to_underlying
+tests\P1831R1_deprecated_volatile_atomic
 tests\P1899R3_views_stride
 tests\P1899R3_views_stride_death
 tests\P1951R1_default_arguments_pair_forward_ctor
diff --git a/tests/std/tests/P1831R1_deprecated_volatile_atomic/env.lst b/tests/std/tests/P1831R1_deprecated_volatile_atomic/env.lst
new file mode 100644
index 00000000000..642f530ffad
--- /dev/null
+++ b/tests/std/tests/P1831R1_deprecated_volatile_atomic/env.lst
@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\usual_latest_matrix.lst
diff --git a/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp b/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp
new file mode 100644
index 00000000000..5528b35b4bc
--- /dev/null
+++ b/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp
@@ -0,0 +1,50 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <atomic>
+#include <cassert>
+
+using namespace std;
+
+#pragma warning(push)
+#pragma warning(disable : 4996)
+
+void test_volatile_inc_dec() {
+    volatile atomic<int> ai{10};
+    (void) ai++;
+    (void) ++ai;
+    (void) ai--;
+    (void) --ai;
+
+    int arr[5] = {0};
+    volatile atomic<int*> ap{arr};
+    (void) ap++;
+    (void) ++ap;
+    (void) ap--;
+    (void) --ap;
+}
+
+#if _HAS_CXX20
+void test_volatile_wait_notify() {
+    volatile atomic<int> ai{0};
+    ai.notify_one();
+    ai.notify_all();
+    ai.wait(1);
+
+    int dummy = 0;
+    volatile atomic<int*> ap{&dummy};
+    ap.notify_one();
+    ap.notify_all();
+    int other = 0;
+    ap.wait(&other);
+}
+#endif // _HAS_CXX20
+
+#pragma warning(pop)
+
+int main() {
+    test_volatile_inc_dec();
+#if _HAS_CXX20
+    test_volatile_wait_notify();
+#endif
+}

From f53191a9684639da81a7628bbee68e2e6c585482 Mon Sep 17 00:00:00 2001
From: Shengxin Pei <TPPPP72@outlook.com>
Date: Fri, 21 Aug 2026 00:14:19 +0800
Subject: [PATCH 2/2] use static_assert and update test

---
 stl/inc/atomic                                | 22 +++++++++----------
 .../test.cpp                                  |  7 ++----
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/stl/inc/atomic b/stl/inc/atomic
index ecd01a238a2..d3c2195b221 100644
--- a/stl/inc/atomic
+++ b/stl/inc/atomic
@@ -1662,23 +1662,23 @@ struct _Atomic_integral_facade : _Atomic_integral<_Ty> {
 
     using _Base::operator++;
     _Ty operator++(int) volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator++(0);
     }
 
     _Ty operator++() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator++();
     }
 
     using _Base::operator--;
     _Ty operator--(int) volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator--(0);
     }
 
     _Ty operator--() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return const_cast<_Atomic_integral_facade*>(this)->_Base::operator--();
     }
 
@@ -1964,7 +1964,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator++(int) volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return fetch_add(1);
     }
 
@@ -1973,7 +1973,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator++() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return fetch_add(1) + 1;
     }
 
@@ -1982,7 +1982,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator--(int) volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return fetch_add(-1);
     }
 
@@ -1991,7 +1991,7 @@ struct _Atomic_pointer : _Atomic_storage<_Ty> {
     }
 
     _Ty operator--() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         return fetch_add(-1) - 1;
     }
 
@@ -2250,19 +2250,19 @@ public:
 #if _HAS_CXX20
     using _Base::wait;
     void wait(const _Ty _Expected, const memory_order _Order = memory_order_seq_cst) const volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         const_cast<const atomic*>(this)->_Base::wait(_Expected, _Order);
     }
 
     using _Base::notify_one;
     void notify_one() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         const_cast<atomic*>(this)->_Base::notify_one();
     }
 
     using _Base::notify_all;
     void notify_all() volatile noexcept {
-        (void) _Deprecate_non_lock_free_volatile<_Ty>;
+        static_assert(_Deprecate_non_lock_free_volatile<_Ty>, "Never fails");
         const_cast<atomic*>(this)->_Base::notify_all();
     }
 #endif // _HAS_CXX20
diff --git a/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp b/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp
index 5528b35b4bc..27acc33406a 100644
--- a/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp
+++ b/tests/std/tests/P1831R1_deprecated_volatile_atomic/test.cpp
@@ -1,14 +1,13 @@
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#define _SILENCE_CXX20_VOLATILE_DEPRECATION_WARNING
+
 #include <atomic>
 #include <cassert>
 
 using namespace std;
 
-#pragma warning(push)
-#pragma warning(disable : 4996)
-
 void test_volatile_inc_dec() {
     volatile atomic<int> ai{10};
     (void) ai++;
@@ -40,8 +39,6 @@ void test_volatile_wait_notify() {
 }
 #endif // _HAS_CXX20
 
-#pragma warning(pop)
-
 int main() {
     test_volatile_inc_dec();
 #if _HAS_CXX20