[libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 #87111

H-G-Hristov · 2024-03-29T21:21:40Z

Implements https://wg21.link/P2869R4
Implements deprecations as per https://wg21.link/P0718R2

github-actions · 2024-03-29T21:24:23Z

✅ With the latest revision this PR passed the C/C++ code formatter.

llvmbot · 2024-03-29T21:29:13Z

@llvm/pr-subscribers-libcxx

Author: Hristo Hristov (H-G-Hristov)

Changes

Implements https://wg21.link/P2869R3

Full diff: https://github.com/llvm/llvm-project/pull/87111.diff

15 Files Affected:

(modified) libcxx/docs/ReleaseNotes/19.rst (+4)
(modified) libcxx/include/__memory/shared_ptr.h (+4)
(modified) libcxx/include/memory (+11-11)
(modified) libcxx/modules/std/memory.inc (+6)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp (+3-2)
(modified) libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp (+3-2)

diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index dd39c1bbbc78a3..577560b490e838 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -42,6 +42,7 @@ Implemented Papers
 - P2652R2 - Disallow User Specialization of ``allocator_traits``
 - P2819R2 - Add ``tuple`` protocol to ``complex``
 - P2495R3 - Interfacing ``stringstream``\s with ``string_view``
+- P2869R3 - Remove Deprecated ``shared_ptr`` Atomic Access APIs from C++26
 - P2302R4 - ``std::ranges::contains``
 - P1659R3 - ``std::ranges::starts_with`` and ``std::ranges::ends_with``
 
@@ -54,6 +55,9 @@ Improvements and New Features
 - The ``std::mismatch`` algorithm has been optimized for integral types, which can lead up to 40x performance
   improvements.
 
+- The ``_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS`` macro has been added to make the declarations in ``<memory>``
+  available.
+
 Deprecations and Removals
 -------------------------
 
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
index 794a794d8fd85a..05d3f4375a71a0 100644
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -1581,6 +1581,8 @@ class _LIBCPP_EXPORTED_FROM_ABI __sp_mut {
 
 _LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
 
+#  if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS)
+
 template <class _Tp>
 inline _LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const shared_ptr<_Tp>*) {
   return false;
@@ -1664,6 +1666,8 @@ inline _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
   return std::atomic_compare_exchange_weak(__p, __v, __w);
 }
 
+#  endif // _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS)
+
 #endif // !defined(_LIBCPP_HAS_NO_THREADS)
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/memory b/libcxx/include/memory
index a8c0264eb9eb78..d7f34b64080dcc 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -830,34 +830,34 @@ public:
 };
 
 template<class T>
-    bool atomic_is_lock_free(const shared_ptr<T>* p);
+    bool atomic_is_lock_free(const shared_ptr<T>* p);                                     // Removed in C++26
 template<class T>
-    shared_ptr<T> atomic_load(const shared_ptr<T>* p);
+    shared_ptr<T> atomic_load(const shared_ptr<T>* p);                                    // Removed in C++26
 template<class T>
-    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);
+    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);          // Removed in C++26
 template<class T>
-    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);
+    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);                                 // Removed in C++26
 template<class T>
-    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);       // Removed in C++26
 template<class T>
-    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);
+    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);                     // Removed in C++26
 template<class T>
     shared_ptr<T>
-    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
+    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);         // Removed in C++26
 template<class T>
     bool
-    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);    // Removed in C++26
 template<class T>
     bool
-    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
+    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w); // Removed in C++26
 template<class T>
     bool
-    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
+    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,             // Removed in C++26
                                           shared_ptr<T> w, memory_order success,
                                           memory_order failure);
 template<class T>
     bool
-    atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
+    atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,           // Removed in C++26
                                             shared_ptr<T> w, memory_order success,
                                             memory_order failure);
 // Hash support
diff --git a/libcxx/modules/std/memory.inc b/libcxx/modules/std/memory.inc
index 56c621c0cf17fb..28afbab67bfc02 100644
--- a/libcxx/modules/std/memory.inc
+++ b/libcxx/modules/std/memory.inc
@@ -190,6 +190,9 @@ export namespace std {
   //  using std::inout_ptr;
 
 #ifndef _LIBCPP_HAS_NO_THREADS
+
+#  if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS)
+
   // [depr.util.smartptr.shared.atomic]
   using std::atomic_is_lock_free;
 
@@ -206,5 +209,8 @@ export namespace std {
   using std::atomic_compare_exchange_strong_explicit;
   using std::atomic_compare_exchange_weak;
   using std::atomic_compare_exchange_weak_explicit;
+  
+#  endif // _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS)
+
 #endif // _LIBCPP_HAS_NO_THREADS
 } // namespace std
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp
index 37be6ceea3e094..0e565c1b0424df 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -15,7 +16,7 @@
 // template <class T>
 // bool
 // atomic_compare_exchange_strong(shared_ptr<T>* p, shared_ptr<T>* v,
-//                                shared_ptr<T> w);
+//                                shared_ptr<T> w);                     // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp
index 3965863b86ccf5..1180c2cc2138a9 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -16,7 +17,7 @@
 // bool
 // atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
 //                                         shared_ptr<T> w, memory_order success,
-//                                         memory_order failure);
+//                                         memory_order failure);                 // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp
index 6dd04f924a105e..6f80c86f6dc214 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -15,7 +16,7 @@
 // template <class T>
 // bool
 // atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v,
-//                              shared_ptr<T> w);
+//                              shared_ptr<T> w);                    // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp
index 4837fa9793a5e8..f15fed4cc8f636 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -16,7 +17,7 @@
 // bool
 // atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
 //                                       shared_ptr<T> w, memory_order success,
-//                                       memory_order failure);
+//                                       memory_order failure);                 // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp
index f488e0ed1d14e1..abf98a364f2ef8 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // shared_ptr<T>
-// atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r)
+// atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r)   // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp
index 1945f7bba6dc06..e6d66878c303de 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // shared_ptr<T>
-// atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r)
+// atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r)  // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp
index 37f7d12eda2c62..3390a64a1358a5 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template<class T>
 // bool
-// atomic_is_lock_free(const shared_ptr<T>* p);
+// atomic_is_lock_free(const shared_ptr<T>* p);    // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp
index 1b9a15ac92ac1f..b298ffe840e287 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // shared_ptr<T>
-// atomic_load(const shared_ptr<T>* p)
+// atomic_load(const shared_ptr<T>* p)      // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp
index 5c2970133328f3..f924f090af297d 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // shared_ptr<T>
-// atomic_load_explicit(const shared_ptr<T>* p, memory_order mo)
+// atomic_load_explicit(const shared_ptr<T>* p, memory_order mo)     // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp
index 5b7bd5fad69c47..5f978fc5f16b32 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // void
-// atomic_store(shared_ptr<T>* p, shared_ptr<T> r)
+// atomic_store(shared_ptr<T>* p, shared_ptr<T> r)   // Removed in C++26
 
 // UNSUPPORTED: c++03
 
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp
index 5712190421308d..62f75533da97bd 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp
@@ -5,7 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS
 // UNSUPPORTED: no-threads
 
 // <memory>
@@ -14,7 +15,7 @@
 
 // template <class T>
 // void
-// atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo)
+// atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo)  // Removed in C++26
 
 // UNSUPPORTED: c++03

…rom C++26 Implements https://wg21.link/P2869R3

mordante

Thanks for working on this!
While reviewing your patch I noticed we have not implemented P0718R2. This paper deprecates shared_ptr Atomic Access APIs. I don't like to remove this feature when we don't issue deprecation messages. Can you implement P0718R2 too? I'm fine to have it in the same patch. If you do it in this patch please update the title and the description.

…link/P0718R2

…red_ptr-Atomic-Access-APIs

H-G-Hristov · 2024-04-09T20:59:46Z

Thanks for working on this! While reviewing your patch I noticed we have not implemented P0718R2. This paper deprecates shared_ptr Atomic Access APIs. I don't like to remove this feature when we don't issue deprecation messages. Can you implement P0718R2 too? I'm fine to have it in the same patch. If you do it in this patch please update the title and the description.

@mordante Thank you for the review. I implemented the deprecations as per P0718R2 The remaining parts of the paper are not a subject of this patch. There is another probably stale PR: #78317 implementing atomic<shared_ptr<T>>.

…red_ptr-Atomic-Access-APIs

mordante

LGTM modulo some minor nits.

mordante · 2024-04-13T10:16:45Z

libcxx/docs/Status/Cxx20Papers.csv

@@ -12,7 +12,7 @@
 "`P0600R1 <https://wg21.link/P0600R1>`__","LWG","nodiscard in the Library","Albuquerque","|Complete|","16.0"
 "`P0616R0 <https://wg21.link/P0616R0>`__","LWG","de-pessimize legacy <numeric> algorithms with std::move","Albuquerque","|Complete|","12.0"
 "`P0653R2 <https://wg21.link/P0653R2>`__","LWG","Utility to convert a pointer to a raw pointer","Albuquerque","|Complete|","6.0"
-"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","",""
+"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","|Partial|","19.0"


This adds a link to the note you created.
In general we only add a version when it's complete, feel free to add the version to the note.

Suggested change

"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","|Partial|","19.0"

"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","|Partial| [#note-P0718]_",""

mordante · 2024-04-13T10:27:28Z

...s/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.verify.cpp

@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//


These deprecated tests are typically in libcxx/test/libcxx/depr/depr.XXX where XXX is the section name in the Standard. They typically have a cxxYY too in their name. (We're not very consistent in this naming but let's match that generic direction.)

…red_ptr-Atomic-Access-APIs

H-G-Hristov · 2024-04-14T17:02:37Z

LGTM modulo some minor nits.

Thank you!

…Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 (llvm#87111) Implements https://wg21.link/P2869R4 Implements deprecations as per https://wg21.link/P0718R2

nico · 2024-05-14T16:12:06Z

As mentioned before, it'd be very useful to have opt-out flags for deprecations.

#80542 (comment) claims that "deprecation warnings are introduced in newer standards only", but in our experience that just isn't true (and isn't true here). The MSVC STL does have an opt-out macro per deprecated thing. (@ldionne)

We're once again in the situation that we can't update libc++ before cleaning up this (and possibly other) deprecation warnings. It would be considerably easier if we could update (with a define to disable this deprecation warning) and the fix the warning asynchronously.

(I didn't notice this earlier because it took us 5 weeks to fix the last thing that we couldn't fix asynchronously, and we just now updated libc++ for the first time in 5 weeks, to the version that was current 5 weeks ago, shortly before this here landed.)

Zingam · 2024-05-15T08:14:34Z

AFAIK that comment states that std::err is applied as DR, which means it is applied to previous standards retroactively.
We don't do that to atomic access APIs here, which are deprecated in C++20 and that C++20 paper (P0718R2) has not been implemented up until now.
If we have a policy to add opt-out flags I'd be happy to implement them.

nico · 2024-05-15T14:43:16Z

We're trying to use the replacement over in google/perfetto#785 . https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2869r2.pdf suggests to use std::atomic<std::shared_ptr<...>>. But we're getting errors that _Atomic cannot be applied to type 'std::shared_ptry<X>' which is not trivially copiable.

Maybe we're holding something wrong, but https://libcxx.llvm.org/FeatureTestMacroTable.html says "__cpp_lib_atomic_shared_ptr unimplemented". Which suggests that the recommended replacement doesn't work in ilbc++ yet.

Is that correct?

If so, I'll suggest that adding this deprecation is premature.

Catch up with chromium's latest libcxx. Bug: llvm/llvm-project#87111 Change-Id: I1d8d1c051feeca592ec064c715106d0b70acfb9e

zmodem · 2024-05-29T08:26:10Z

@mordante and @H-G-Hristov: ping? Have you had a chance to consider nico's comment above?

This patch reverts 9b832b7 (#87111): - [libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 - [libc++] Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 As explained in [1], the suggested replacement in P2869R3 is `__cpp_lib_atomic_shared_ptr`, which libc++ does not yet implement. Let's not deprecate the old way of doing things before the new way of doing things exists. [1]: #87111 (comment)

This patch reverts 9b832b72 (#87111): - [libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 - [libc++] Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 As explained in [1], the suggested replacement in P2869R3 is `__cpp_lib_atomic_shared_ptr`, which libc++ does not yet implement. Let's not deprecate the old way of doing things before the new way of doing things exists. [1]: llvm/llvm-project#87111 (comment) NOKEYCHECK=True GitOrigin-RevId: 716ed5fccd2a960981fec2c5acb17292a1502435

Zingam added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Mar 29, 2024

H-G-Hristov marked this pull request as ready for review March 31, 2024 04:02

H-G-Hristov requested a review from a team as a code owner March 31, 2024 04:02

H-G-Hristov force-pushed the hgh/libcxx/P2869R3-Remove-Deprecated-std_shared_ptr-Atomic-Access-APIs branch from 3e8d1c9 to 69715ec Compare April 4, 2024 20:12

H-G-Hristov added 3 commits April 5, 2024 23:14

[libc++] P2869R3: Remove Deprecated shared_ptr Atomic Access APIs f…

f8060ad

…rom C++26 Implements https://wg21.link/P2869R3

Try to fix CI

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Updated release notes and status pages

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H-G-Hristov force-pushed the hgh/libcxx/P2869R3-Remove-Deprecated-std_shared_ptr-Atomic-Access-APIs branch from 69715ec to 303cb9a Compare April 5, 2024 20:16

Minor tweaks

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mordante self-assigned this Apr 7, 2024

mordante requested changes Apr 7, 2024

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Addressed review comments: Implements deprecations from https://wg21.…

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…link/P0718R2

H-G-Hristov changed the title ~~[libc++] P2869R3: Remove Deprecated shared_ptr Atomic Access APIs from C++26~~ [libc++] P2869R3: Remove Deprecated shared_ptr Atomic Access APIs from C++26 & Deprecated shared_ptr Atomic Access APIs from P0718R2 Apr 9, 2024

H-G-Hristov added 2 commits April 9, 2024 23:35

Fixed formatting

535bcf8

Merge branch 'main' into hgh/libcxx/P2869R3-Remove-Deprecated-std_sha…

e2a97a6

…red_ptr-Atomic-Access-APIs

Zingam requested a review from mordante April 10, 2024 04:50

H-G-Hristov added 2 commits April 11, 2024 10:00

Updated paper status

21e2f3a

Merge branch 'main' into hgh/libcxx/P2869R3-Remove-Deprecated-std_sha…

bf87944

…red_ptr-Atomic-Access-APIs

mordante approved these changes Apr 13, 2024

View reviewed changes

H-G-Hristov added 3 commits April 13, 2024 22:33

Addressed comments

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Renamed deprecated tests

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Merge branch 'main' into hgh/libcxx/P2869R3-Remove-Deprecated-std_sha…

9e33ace

…red_ptr-Atomic-Access-APIs

Zingam merged commit 9b832b7 into llvm:main Apr 14, 2024
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H-G-Hristov deleted the hgh/libcxx/P2869R3-Remove-Deprecated-std_shared_ptr-Atomic-Access-APIs branch April 14, 2024 17:04

nico mentioned this pull request May 14, 2024

tracing_muxer_impl.cc calls deprecated version of std::atomic_store google/perfetto#785

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primiano added a commit to google/perfetto that referenced this pull request May 15, 2024

Uprev libcxx

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Catch up with chromium's latest libcxx. Bug: llvm/llvm-project#87111 Change-Id: I1d8d1c051feeca592ec064c715106d0b70acfb9e

nico mentioned this pull request May 21, 2024

Revert "[libc++] Deprecated shared_ptr Atomic Access APIs as per P0… #92920

Merged

Zingam mentioned this pull request Aug 1, 2024

[libcxx][P1831R1] Deprecating volatile: library #101439

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Zingam mentioned this pull request Aug 21, 2024

P2869R4: Remove Deprecated shared_ptr Atomic Access APIs from C++26 #105412

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[libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 #87111

[libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 #87111

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	"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","\|Partial\|","19.0"
	"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","\|Partial\| [#note-P0718]_",""

		@@ -0,0 +1,32 @@
		//===----------------------------------------------------------------------===//

[libc++] Deprecated shared_ptr Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated shared_ptr Atomic Access APIs from C++26 #87111

[libc++] Deprecated shared_ptr Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated shared_ptr Atomic Access APIs from C++26 #87111

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[libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 #87111

[libc++] Deprecated `shared_ptr` Atomic Access APIs as per P0718R2 & Implemented P2869R3: Remove Deprecated `shared_ptr` Atomic Access APIs from C++26 #87111

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