[libc++] Deprecates and removes shared_ptr::unqiue. #76576
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The status table incorrectly marks P0521R0 as nothing to do. This is not correct the function should be deprecated. During our latest monthly meeting we argreed to remove the _LIBCPP_ENABLE_CXXyy_REMOVED_FEATURES macros, therefore the new macro is not added to that global list. Implements - P0521R0 Proposed Resolution for CA 14 (shared_ptr use_count/unique) Implements parts of - P0619R4 Reviewing Deprecated Facilities of C++17 for C++20
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@llvm/pr-subscribers-libcxx Author: Mark de Wever (mordante) ChangesThe status table incorrectly marks P0521R0 as nothing to do. This is not correct the function should be deprecated. Implements
Implements parts of
Full diff: https://github.com/llvm/llvm-project/pull/76576.diff 9 Files Affected:
diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst
index 79608c631f1e62..fa60a581652d6a 100644
--- a/libcxx/docs/ReleaseNotes/18.rst
+++ b/libcxx/docs/ReleaseNotes/18.rst
@@ -57,6 +57,7 @@ Implemented Papers
- P2871R3 - Remove Deprecated Unicode Conversion Facets from C++26
- P2870R3 - Remove basic_string::reserve()
- P2909R4 - Fix formatting of code units as integers (Dude, where’s my ``char``?)
+- P0521R0 - Proposed Resolution for CA 14 (shared_ptr use_count/unique)
Improvements and New Features
@@ -83,6 +84,9 @@ Improvements and New Features
- The ``_LIBCPP_ENABLE_CXX26_REMOVED_STRING_RESERVE`` macro has been added to make
the function ``std::basic_string<...>::reserve()`` available.
+- The ``_LIBCPP_ENABLE_CXX20_REMOVED_SHARED_PTR_UNIQUE`` macro has been added to make
+ the function ``std::shared_ptr<...>::unique()`` available.
+
Deprecations and Removals
-------------------------
diff --git a/libcxx/docs/Status/Cxx17Papers.csv b/libcxx/docs/Status/Cxx17Papers.csv
index 9010402effc5f4..8952391afc83b6 100644
--- a/libcxx/docs/Status/Cxx17Papers.csv
+++ b/libcxx/docs/Status/Cxx17Papers.csv
@@ -87,7 +87,7 @@
"`P0513R0 <https://wg21.link/P0513R0>`__","LWG","Poisoning the Hash","Issaquah","|Complete|","5.0"
"`P0516R0 <https://wg21.link/P0516R0>`__","LWG","Clarify That shared_future's Copy Operations have Wide Contracts","Issaquah","|Complete|","4.0"
"`P0517R0 <https://wg21.link/P0517R0>`__","LWG","Make future_error Constructible","Issaquah","|Complete|","4.0"
-"`P0521R0 <https://wg21.link/P0521R0>`__","LWG","Proposed Resolution for CA 14 (shared_ptr use_count/unique)","Issaquah","|Nothing To Do|","n/a"
+"`P0521R0 <https://wg21.link/P0521R0>`__","LWG","Proposed Resolution for CA 14 (shared_ptr use_count/unique)","Issaquah","|Complete|","18.0"
"","","","","",""
"`P0156R2 <https://wg21.link/P0156R2>`__","LWG","Variadic Lock guard(rev 5)","Kona","|Complete|","5.0"
"`P0270R3 <https://wg21.link/P0270R3>`__","CWG","Removing C dependencies from signal handler wording","Kona","",""
diff --git a/libcxx/docs/Status/Cxx20.rst b/libcxx/docs/Status/Cxx20.rst
index 227b3197d82e68..2deb82547d6310 100644
--- a/libcxx/docs/Status/Cxx20.rst
+++ b/libcxx/docs/Status/Cxx20.rst
@@ -44,7 +44,7 @@ Paper Status
.. [#note-P0645] P0645: The paper is implemented but still marked as an incomplete feature
(the feature-test macro is not set).
.. [#note-P0966] P0966: It was previously erroneously marked as complete in version 8.0. See `bug 45368 <https://llvm.org/PR45368>`__.
- .. [#note-P0619] P0619: Only sections D.8, D.9, D.10 and D.13 are implemented. Sections D.4, D.7, D.11, D.12, and D.14 remain undone.
+ .. [#note-P0619] P0619: Only sections D.8, D.9, D.10 and D.13 are implemented. Sections D.4, D.7, D.11, and D.12 remain undone.
.. [#note-P0883.1] P0883: shared_ptr and floating-point changes weren't applied as they themselves aren't implemented yet.
.. [#note-P0883.2] P0883: ``ATOMIC_FLAG_INIT`` was marked deprecated in version 14.0, but was undeprecated with the implementation of LWG3659 in version 15.0.
.. [#note-P2231] P2231: Optional is complete. The changes to variant haven't been implemented yet.
diff --git a/libcxx/docs/UsingLibcxx.rst b/libcxx/docs/UsingLibcxx.rst
index 8d9f795da977e3..e1bbf39b9634a3 100644
--- a/libcxx/docs/UsingLibcxx.rst
+++ b/libcxx/docs/UsingLibcxx.rst
@@ -296,6 +296,10 @@ C++17 Specific Configuration Macros
C++20 Specific Configuration Macros
-----------------------------------
+**_LIBCPP_ENABLE_CXX20_REMOVED_SHARED_PTR_UNIQUE**
+ This macro is used to re-enable the function
+ ``std::shared_ptr<...>::unique()``.
+
**_LIBCPP_ENABLE_CXX20_REMOVED_FEATURES**:
This macro is used to re-enable all the features removed in C++20. The effect
is equivalent to manually defining each macro listed below.
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
index a868093026c56d..9aa938b2203121 100644
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -723,7 +723,9 @@ class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr {
_LIBCPP_HIDE_FROM_ABI long use_count() const _NOEXCEPT { return __cntrl_ ? __cntrl_->use_count() : 0; }
- _LIBCPP_HIDE_FROM_ABI bool unique() const _NOEXCEPT { return use_count() == 1; }
+#if _LIBCPP_STD_VER < 20 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_SHARED_PTR_UNIQUE)
+ _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI bool unique() const _NOEXCEPT { return use_count() == 1; }
+#endif
_LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return get() != nullptr; }
diff --git a/libcxx/include/memory b/libcxx/include/memory
index 71e812064646b9..ee245d5fd2dcb2 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -629,7 +629,7 @@ public:
T& operator*() const noexcept;
T* operator->() const noexcept;
long use_count() const noexcept;
- bool unique() const noexcept;
+ bool unique() const noexcept; // deprected in C++17, removed in C++20
explicit operator bool() const noexcept;
template<class U> bool owner_before(shared_ptr<U> const& b) const noexcept;
template<class U> bool owner_before(weak_ptr<U> const& b) const noexcept;
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.deprecated_in_cxx17.verify.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.deprecated_in_cxx17.verify.cpp
new file mode 100644
index 00000000000000..f187ce0f755166
--- /dev/null
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.deprecated_in_cxx17.verify.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++20, c++23, c++26
+
+// <memory>
+
+// shared_ptr
+
+// bool unique() const; // deprecated in C++17, removed in C++20
+
+#include <memory>
+
+void f() {
+ const std::shared_ptr<int> p;
+ p.unique(); // expected-warning {{'unique' is deprecated}}
+}
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.pass.cpp
index 0b7d29dbcc06d6..c767701d55c99b 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.pass.cpp
@@ -10,7 +10,9 @@
// shared_ptr
-// bool unique() const;
+// bool unique() const; // deprecated in C++17, removed in C++20
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS -D_LIBCPP_ENABLE_CXX20_REMOVED_SHARED_PTR_UNIQUE
#include <memory>
#include <cassert>
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.removed_in_cxx20.verify.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.removed_in_cxx20.verify.cpp
new file mode 100644
index 00000000000000..c149f032e9a432
--- /dev/null
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.removed_in_cxx20.verify.cpp
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// <memory>
+
+// shared_ptr
+
+// bool unique() const; // deprecated in C++17, removed in C++20
+
+#include <memory>
+
+void f() {
+ const std::shared_ptr<int> p;
+ p.unique(); // expected-error {{no member named 'unique' in 'std::shared_ptr<int>}}
+}
|
philnik777
approved these changes
Dec 30, 2023
...smartptr/util.smartptr.shared/util.smartptr.shared.obs/unique.deprecated_in_cxx17.verify.cpp
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…hared/util.smartptr.shared.obs/unique.deprecated_in_cxx17.verify.cpp Co-authored-by: Nikolas Klauser <[email protected]>
|
As always, please provide an opt-out for this for a release, so that it's possible to roll this in, and then do the cleanup async after the update. (The basic_string removal for example took us months due to deps being slow in accepting PRs. That's done now, but without advance notice before the removal, we we wouldn't have been able to update libc++ for months, and in the meantime a bunch of similar things would have landed.) |
There is an opt-out |
|
I apologize for my lack of reading comprehension, sorry! Thank you for providing an opt-out. We can try to listen in on the monthly libc++ meeting. Is following https://discourse.llvm.org/t/monthly-libc-meeting/74150/5 for the next occurrence the best way to be informed of upcoming meetings? |
The Community Calendar should contain the most up-to-date information: https://calendar.google.com/calendar/u/0/[email protected] We also have the rolling agenda here: https://docs.google.com/document/d/1yC-3bE6pefVizUhfiUs1Shv11EzuL0KOklGSLqto6dk/edit#heading=h.4sl73a7bnqpw |
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The status table incorrectly marks P0521R0 as nothing to do. This is not correct the function should be deprecated.
During our latest monthly meeting we argreed to remove the
_LIBCPP_ENABLE_CXXyy_REMOVED_FEATURES macros, therefore the new macro is not
added to that global list.
Implements
Implements parts of