[libc++] Undeprecate shared_ptr atomic access APIs (#92920)

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)
llvm · Jun 7, 2024 · 716ed5f · 716ed5f
1 parent 35fa2de
commit 716ed5f
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diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
@@ -43,7 +43,6 @@ Implemented Papers
 - P2819R2 - Add ``tuple`` protocol to ``complex``
 - P2495R3 - Interfacing ``stringstream``\s with ``string_view``
 - P2867R2 - Remove Deprecated ``strstream``\s From C++26
-- P2869R4 - Remove Deprecated ``shared_ptr`` Atomic Access APIs from C++26
 - P2872R3 - Remove ``wstring_convert`` From C++26
 - P3142R0 - Printing Blank Lines with ``println`` (as DR against C++23)
 - P2944R3 - Comparisons for ``reference_wrapper`` (comparison operators for ``reference_wrapper`` only)
@@ -69,9 +68,6 @@ Improvements and New Features
 
 - The ``_LIBCPP_ENABLE_CXX26_REMOVED_STRSTREAM`` macro has been added to make the declarations in ``<strstream>`` available.
 
-- The ``_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS`` macro has been added to make the declarations in ``<memory>``
-  available.
-
 - The ``_LIBCPP_ENABLE_CXX26_REMOVED_WSTRING_CONVERT`` macro has been added to make the declarations in ``<locale>``
   available.
 

diff --git a/libcxx/docs/Status/Cxx20.rst b/libcxx/docs/Status/Cxx20.rst
@@ -58,8 +58,6 @@ Paper Status
       * ``GPS clock`` not done
       * ``UTC clock`` not done
 
-   .. [#note-P0718] P0718: Implemented deprecation of ``shared_ptr`` atomic access APIs only.
-
 .. _issues-status-cxx20:
 
 Library Working Group Issues Status

diff --git a/libcxx/docs/Status/Cxx20Papers.csv b/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","|Partial| [#note-P0718]_",""
+"`P0718R2 <https://wg21.link/P0718R2>`__","LWG","Atomic shared_ptr","Albuquerque","",""
 "`P0767R1 <https://wg21.link/P0767R1>`__","CWG","Deprecate POD","Albuquerque","|Complete|","7.0"
 "`P0768R1 <https://wg21.link/P0768R1>`__","CWG","Library Support for the Spaceship (Comparison) Operator","Albuquerque","|Complete|",""
 "`P0777R1 <https://wg21.link/P0777R1>`__","LWG","Treating Unnecessary ``decay``\ ","Albuquerque","|Complete|","7.0"

diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -48,7 +48,7 @@
 "","","","","","",""
 "`P2875R4 <https://wg21.link/P2875R4>`__","LWG","Undeprecate ``polymorphic_allocator::destroy`` for C++26","Tokyo March 2024","|Complete|","15.0",""
 "`P2867R2 <https://wg21.link/P2867R2>`__","LWG","Remove Deprecated ``strstreams`` From C++26","Tokyo March 2024","|Complete|","19.0",""
-"`P2869R4 <https://wg21.link/P2869R4>`__","LWG","Remove Deprecated ``shared_ptr`` Atomic Access APIs from C++26","Tokyo March 2024","|Complete|","19.0",""
+"`P2869R4 <https://wg21.link/P2869R4>`__","LWG","Remove Deprecated ``shared_ptr`` Atomic Access APIs from C++26","Tokyo March 2024","","",""
 "`P2872R3 <https://wg21.link/P2872R3>`__","LWG","Remove ``wstring_convert`` From C++26","Tokyo March 2024","|Complete|","19.0",""
 "`P3107R5 <https://wg21.link/P3107R5>`__","LWG","Permit an efficient implementation of ``std::print``","Tokyo March 2024","","","|format| |DR|"
 "`P3142R0 <https://wg21.link/P3142R0>`__","LWG","Printing Blank Lines with ``println``","Tokyo March 2024","|Complete| [#note-P3142R0]_","19.0","|format|"

diff --git a/libcxx/docs/UsingLibcxx.rst b/libcxx/docs/UsingLibcxx.rst
@@ -252,14 +252,10 @@ C++26 Specific Configuration Macros
 **_LIBCPP_ENABLE_CXX26_REMOVED_STRSTREAM**:
   This macro is used to re-enable all named declarations in ``<strstream>``.
 
-**_LIBCPP_ENABLE_CXX26_REMOVED_SHARED_PTR_ATOMICS**:
-  This macro is used to re-enable all ``shared_ptr`` atomic access APIs in ``<memory>``.
-
 **_LIBCPP_ENABLE_CXX26_REMOVED_WSTRING_CONVERT**:
   This macro is used to re-enable the ``wstring_convert`` and ``wbuffer_convert``
   in ``<locale>``.
 
-
 Libc++ Extensions
 =================
 

diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
@@ -1583,15 +1583,13 @@ 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>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const shared_ptr<_Tp>*) {
+inline _LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const shared_ptr<_Tp>*) {
   return false;
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load(const shared_ptr<_Tp>* __p) {
+_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load(const shared_ptr<_Tp>* __p) {
   __sp_mut& __m = std::__get_sp_mut(__p);
   __m.lock();
   shared_ptr<_Tp> __q = *__p;
@@ -1600,28 +1598,25 @@ _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load(co
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
-atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order) {
+inline _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order) {
   return std::atomic_load(__p);
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
+_LIBCPP_HIDE_FROM_ABI void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
   __sp_mut& __m = std::__get_sp_mut(__p);
   __m.lock();
   __p->swap(__r);
   __m.unlock();
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void
-atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
+inline _LIBCPP_HIDE_FROM_ABI void atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
   std::atomic_store(__p, __r);
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
-atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
+_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
   __sp_mut& __m = std::__get_sp_mut(__p);
   __m.lock();
   __p->swap(__r);
@@ -1630,13 +1625,13 @@ atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) {
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
+inline _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
 atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order) {
   return std::atomic_exchange(__p, __r);
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool
+_LIBCPP_HIDE_FROM_ABI bool
 atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
   shared_ptr<_Tp> __temp;
   __sp_mut& __m = std::__get_sp_mut(__p);
@@ -1654,25 +1649,23 @@ atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, share
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool
+inline _LIBCPP_HIDE_FROM_ABI bool
 atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w) {
   return std::atomic_compare_exchange_strong(__p, __v, __w);
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
+inline _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
     shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
   return std::atomic_compare_exchange_strong(__p, __v, __w);
 }
 
 template <class _Tp>
-_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
+inline _LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
     shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w, memory_order, memory_order) {
   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
@@ -830,34 +830,34 @@ public:
 };
 
 template<class T>
-    bool atomic_is_lock_free(const shared_ptr<T>* p);                                     // Deprecated in C++20, removed in C++26
+    bool atomic_is_lock_free(const shared_ptr<T>* p);
 template<class T>
-    shared_ptr<T> atomic_load(const shared_ptr<T>* p);                                    // Deprecated in C++20, removed in C++26
+    shared_ptr<T> atomic_load(const shared_ptr<T>* p);
 template<class T>
-    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);          // Deprecated in C++20, removed in C++26
+    shared_ptr<T> atomic_load_explicit(const shared_ptr<T>* p, memory_order mo);
 template<class T>
-    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);                                 // Deprecated in C++20, removed in C++26
+    void atomic_store(shared_ptr<T>* p, shared_ptr<T> r);
 template<class T>
-    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);       // Deprecated in C++20, removed in C++26
+    void atomic_store_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
 template<class T>
-    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);                     // Deprecated in C++20, removed in C++26
+    shared_ptr<T> atomic_exchange(shared_ptr<T>* p, shared_ptr<T> r);
 template<class T>
     shared_ptr<T>
-    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);         // Deprecated in C++20, removed in C++26
+    atomic_exchange_explicit(shared_ptr<T>* p, shared_ptr<T> r, memory_order mo);
 template<class T>
     bool
-    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);    // Deprecated in C++20, removed in C++26
+    atomic_compare_exchange_weak(shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
 template<class T>
     bool
-    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w); // Deprecated in C++20, removed in C++26
+    atomic_compare_exchange_strong( shared_ptr<T>* p, shared_ptr<T>* v, shared_ptr<T> w);
 template<class T>
     bool
-    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,             // Deprecated in C++20, removed in C++26
+    atomic_compare_exchange_weak_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
                                           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,           // Deprecated in C++20, removed in C++26
+    atomic_compare_exchange_strong_explicit(shared_ptr<T>* p, shared_ptr<T>* v,
                                             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
@@ -190,9 +190,6 @@ 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;
 
@@ -209,8 +206,5 @@ 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/...depr.util.smartptr.shared.atomic/atomic_compare_exchange_strong.depr_in_cxx20..verify.cpp b/...depr.util.smartptr.shared.atomic/atomic_compare_exchange_strong.depr_in_cxx20..verify.cpp
diff --git a/...l.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.depr_in_cxx20.verify.cpp b/...l.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.depr_in_cxx20.verify.cpp
diff --git a/...r/depr.util.smartptr.shared.atomic/atomic_compare_exchange_weak.depr_in_cxx20..verify.cpp b/...r/depr.util.smartptr.shared.atomic/atomic_compare_exchange_weak.depr_in_cxx20..verify.cpp
diff --git a/...il.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.depr_in_cxx20..verify.cpp b/...il.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.depr_in_cxx20..verify.cpp
diff --git a/...st/libcxx/depr/depr.util.smartptr.shared.atomic/atomic_exchange.depr_in_cxx20..verify.cpp b/...st/libcxx/depr/depr.util.smartptr.shared.atomic/atomic_exchange.depr_in_cxx20..verify.cpp