[libc++] Remove the allocator<const T> extension #96319

ldionne · 2024-06-21T15:20:25Z

This effort has quite a history:

This was first attempted in 2022 via bed3240, which broke std::shared_ptr and caused the change to be reverted in 9138666.
We then re-attempted landing the change in 276ca87 after fixing std::shared_ptr, but reports were made that this broke code en masse within Google. This led to the patch being reverted again in a54d028 with the goal to land this again with a migration path for vendors.

This patch re-lands the removal while providing a migration path for vendors by providing the _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST macro. This macro will be honored for the LLVM 19 release and will be removed after that, at which point allocator will be removed unconditionally.

Fixes #73665

This effort has quite a history: - This was first attempted in 2022 via bed3240, which broke std::shared_ptr<T const> and caused the change to be reverted in 9138666. - We then re-attempted landing the change in 276ca87 after fixing std::shared_ptr, but reports were made that this broke code en masse within Google. This led to the patch being reverted again in a54d028 with the goal to land this again with a migration path for vendors. This patch re-lands the removal while providing a migration path for vendors by providing the `_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST` macro. This macro will be honored for the LLVM 19 release and will be removed after that, at which point allocator<const T> will be removed unconditionally. Fixes llvm#73665

ldionne · 2024-06-21T15:20:42Z

Pinging @llvm/libcxx-vendors for awareness.

llvmbot · 2024-06-21T15:20:58Z

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

This effort has quite a history:

This was first attempted in 2022 via bed3240, which broke std::shared_ptr<T const> and caused the change to be reverted in 9138666.
We then re-attempted landing the change in 276ca87 after fixing std::shared_ptr, but reports were made that this broke code en masse within Google. This led to the patch being reverted again in a54d028 with the goal to land this again with a migration path for vendors.

This patch re-lands the removal while providing a migration path for vendors by providing the _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST macro. This macro will be honored for the LLVM 19 release and will be removed after that, at which point allocator<const T> will be removed unconditionally.

Fixes #73665

Patch is 20.92 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/96319.diff

17 Files Affected:

(modified) libcxx/docs/ReleaseNotes/19.rst (+6)
(modified) libcxx/include/__memory/allocator.h (+15-13)
(modified) libcxx/include/__memory/shared_ptr.h (+6-6)
(removed) libcxx/test/libcxx/containers/sequences/vector/const_T.compile.pass.cpp (-18)
(removed) libcxx/test/libcxx/containers/sequences/vector/const_value_type.pass.cpp (-25)
(modified) libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp (-12)
(modified) libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp (+1-9)
(modified) libcxx/test/libcxx/memory/allocator_volatile.verify.cpp (+3-3)
(modified) libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp (-6)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp (+2-2)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp (-6)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp (-1)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp (-1)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp (-7)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp (-3)
(modified) libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp (+1-1)
(modified) libcxx/test/std/utilities/memory/specialized.algorithms/specialized.construct/construct_at.pass.cpp (+2-2)

diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index 71de10abb6eaa..31a2cacc2bf70 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -121,6 +121,12 @@ Deprecations and Removals
 - The ``_LIBCPP_DISABLE_ADDITIONAL_DIAGNOSTICS`` macro has been removed and is not honored anymore. Additional
   warnings provided by libc++ as a matter of QoI will now be provided unconditionally.
 
+- libc++ no longer supports ``std::allocator<const T>`` and containers of ``const``-qualified element type, such
+  as ``std::vector<const T>`` and ``std::list<const T>``. This used to be supported as an undocumented extension.
+  If you were using ``std::vector<const T>``, replace it with ``std::vector<T>`` instead. The
+  ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro can be defined to temporarily re-enable this extension as
+  folks transition their code. This macro will be honored for one released and ignored starting in LLVM 20.
+
 
 Upcoming Deprecations and Removals
 ----------------------------------
diff --git a/libcxx/include/__memory/allocator.h b/libcxx/include/__memory/allocator.h
index 215d3832f9ef3..2d8624e771bce 100644
--- a/libcxx/include/__memory/allocator.h
+++ b/libcxx/include/__memory/allocator.h
@@ -14,6 +14,7 @@
 #include <__memory/addressof.h>
 #include <__memory/allocate_at_least.h>
 #include <__memory/allocator_traits.h>
+#include <__type_traits/is_const.h>
 #include <__type_traits/is_constant_evaluated.h>
 #include <__type_traits/is_same.h>
 #include <__type_traits/is_void.h>
@@ -36,8 +37,6 @@ class allocator;
 // Specializing allocator<void> is deprecated, but not using it.
 template <>
 class _LIBCPP_TEMPLATE_VIS allocator<void> {
-#  if _LIBCPP_STD_VER <= 17
-
 public:
   _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;
@@ -47,13 +46,12 @@ class _LIBCPP_TEMPLATE_VIS allocator<void> {
   struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
     typedef allocator<_Up> other;
   };
-#  endif
 };
 
+// TODO(LLVM 20): Remove the escape hatch
+#  ifdef _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
 template <>
 class _LIBCPP_TEMPLATE_VIS allocator<const void> {
-#  if _LIBCPP_STD_VER <= 17
-
 public:
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;
@@ -63,9 +61,9 @@ class _LIBCPP_TEMPLATE_VIS allocator<const void> {
   struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
     typedef allocator<_Up> other;
   };
-#  endif
 };
-#endif
+#  endif // _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
+#endif   // _LIBCPP_STD_VER <= 17
 
 // This class provides a non-trivial default constructor to the class that derives from it
 // if the condition is satisfied.
@@ -94,6 +92,7 @@ struct __non_trivial_if<true, _Unique> {
 
 template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > {
+  static_assert(!is_const<_Tp>::value, "std::allocator does not support const types");
   static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
 
 public:
@@ -170,6 +169,8 @@ class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::v
 #endif
 };
 
+// TODO(LLVM 20): Remove the escape hatch
+#ifdef _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
 template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
     : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> > {
@@ -180,9 +181,9 @@ class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
   typedef ptrdiff_t difference_type;
   typedef const _Tp value_type;
   typedef true_type propagate_on_container_move_assignment;
-#if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
+#  if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
   _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;
-#endif
+#  endif
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;
 
@@ -199,11 +200,11 @@ class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
     }
   }
 
-#if _LIBCPP_STD_VER >= 23
+#  if _LIBCPP_STD_VER >= 23
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<const _Tp*> allocate_at_least(size_t __n) {
     return {allocate(__n), __n};
   }
-#endif
+#  endif
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(const _Tp* __p, size_t __n) {
     if (__libcpp_is_constant_evaluated()) {
@@ -214,7 +215,7 @@ class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
   }
 
   // C++20 Removed members
-#if _LIBCPP_STD_VER <= 17
+#  if _LIBCPP_STD_VER <= 17
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& reference;
@@ -243,8 +244,9 @@ class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
   }
 
   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }
-#endif
+#  endif
 };
+#endif // _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
 
 template <class _Tp, class _Up>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
index 358a851958db1..a7917ae3952bf 100644
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -259,7 +259,7 @@ struct __shared_ptr_emplace : __shared_weak_count {
             class _Allocator                                                                          = _Alloc,
             __enable_if_t<!is_same<typename _Allocator::value_type, __for_overwrite_tag>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI explicit __shared_ptr_emplace(_Alloc __a, _Args&&... __args) : __storage_(std::move(__a)) {
-    using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
+    using _TpAlloc = typename __allocator_traits_rebind<_Alloc, __remove_cv_t<_Tp> >::type;
     _TpAlloc __tmp(*__get_alloc());
     allocator_traits<_TpAlloc>::construct(__tmp, __get_elem(), std::forward<_Args>(__args)...);
   }
@@ -278,7 +278,7 @@ struct __shared_ptr_emplace : __shared_weak_count {
   template <class _Allocator                                                                          = _Alloc,
             __enable_if_t<!is_same<typename _Allocator::value_type, __for_overwrite_tag>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __on_zero_shared_impl() _NOEXCEPT {
-    using _TpAlloc = typename __allocator_traits_rebind<_Allocator, _Tp>::type;
+    using _TpAlloc = typename __allocator_traits_rebind<_Allocator, __remove_cv_t<_Tp> >::type;
     _TpAlloc __tmp(*__get_alloc());
     allocator_traits<_TpAlloc>::destroy(__tmp, __get_elem());
   }
@@ -598,7 +598,7 @@ class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr {
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
   template <class _Yp, __enable_if_t<is_convertible<_Yp*, element_type*>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI shared_ptr(auto_ptr<_Yp>&& __r) : __ptr_(__r.get()) {
-    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
+    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<__remove_cv_t<_Yp> > > _CntrlBlk;
     __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
     __enable_weak_this(__r.get(), __r.get());
     __r.release();
@@ -776,7 +776,7 @@ class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr {
 private:
   template <class _Yp, bool = is_function<_Yp>::value>
   struct __shared_ptr_default_allocator {
-    typedef allocator<_Yp> type;
+    typedef allocator<__remove_cv_t<_Yp> > type;
   };
 
   template <class _Yp>
@@ -834,7 +834,7 @@ _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> allocate_shared(const _Alloc& __a, _Args&&
 
 template <class _Tp, class... _Args, __enable_if_t<!is_array<_Tp>::value, int> = 0>
 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> make_shared(_Args&&... __args) {
-  return std::allocate_shared<_Tp>(allocator<_Tp>(), std::forward<_Args>(__args)...);
+  return std::allocate_shared<_Tp>(allocator<__remove_cv_t<_Tp> >(), std::forward<_Args>(__args)...);
 }
 
 #if _LIBCPP_STD_VER >= 20
@@ -848,7 +848,7 @@ _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> allocate_shared_for_overwrite(const _Alloc
 
 template <class _Tp, __enable_if_t<!is_array<_Tp>::value, int> = 0>
 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> make_shared_for_overwrite() {
-  return std::allocate_shared_for_overwrite<_Tp>(allocator<_Tp>());
+  return std::allocate_shared_for_overwrite<_Tp>(allocator<__remove_cv_t<_Tp>>());
 }
 
 #endif // _LIBCPP_STD_VER >= 20
diff --git a/libcxx/test/libcxx/containers/sequences/vector/const_T.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector/const_T.compile.pass.cpp
deleted file mode 100644
index 62fff96ac5abe..0000000000000
--- a/libcxx/test/libcxx/containers/sequences/vector/const_T.compile.pass.cpp
+++ /dev/null
@@ -1,18 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// Make sure that `vector<const T>` works
-
-#include <vector>
-
-void test() {
-  std::vector<const int> v;
-  v.emplace_back(1);
-  v.push_back(1);
-  v.resize(3);
-}
diff --git a/libcxx/test/libcxx/containers/sequences/vector/const_value_type.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector/const_value_type.pass.cpp
deleted file mode 100644
index 1ad505a76d3fb..0000000000000
--- a/libcxx/test/libcxx/containers/sequences/vector/const_value_type.pass.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-
-// <vector>
-
-// vector<const int> v;  // an extension
-
-#include <vector>
-#include <type_traits>
-
-#include "test_macros.h"
-
-int main(int, char**)
-{
-    std::vector<const int> v = {1, 2, 3};
-
-  return 0;
-}
diff --git a/libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp
index 210d269c9fa23..646569e3d573a 100644
--- a/libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp
@@ -39,15 +39,3 @@ void test_allocator() {
   allocator.allocate_at_least(1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
 #endif
 }
-
-void test_const_allocator() {
-  std::allocator<const int> allocator;
-  allocator.allocate(1);          // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-
-#if TEST_STD_VER <= 17
-  allocator.allocate(1, nullptr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-#endif
-#if TEST_STD_VER >= 23
-  allocator.allocate_at_least(1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
-#endif
-}
diff --git a/libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp b/libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp
index f9d67c065de85..69a4b8943caa6 100644
--- a/libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp
+++ b/libcxx/test/libcxx/memory/allocator_void.trivial.compile.pass.cpp
@@ -17,18 +17,10 @@
 #include <type_traits>
 
 typedef std::allocator<void> A1;
-typedef std::allocator<void const> A2;
-struct A3 : std::allocator<void> { };
-struct A4 : std::allocator<void const> { };
+struct A2 : std::allocator<void> { };
 
 static_assert(std::is_trivially_default_constructible<A1>::value, "");
 static_assert(std::is_trivial<A1>::value, "");
 
 static_assert(std::is_trivially_default_constructible<A2>::value, "");
 static_assert(std::is_trivial<A2>::value, "");
-
-static_assert(std::is_trivially_default_constructible<A3>::value, "");
-static_assert(std::is_trivial<A3>::value, "");
-
-static_assert(std::is_trivially_default_constructible<A4>::value, "");
-static_assert(std::is_trivial<A4>::value, "");
diff --git a/libcxx/test/libcxx/memory/allocator_volatile.verify.cpp b/libcxx/test/libcxx/memory/allocator_volatile.verify.cpp
index 6fa7fe1b1aeda..53fdc08e7a024 100644
--- a/libcxx/test/libcxx/memory/allocator_volatile.verify.cpp
+++ b/libcxx/test/libcxx/memory/allocator_volatile.verify.cpp
@@ -6,9 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-// http://wg21.link/LWG2447 gives implementors freedom to reject volatile types in `std::allocator`.
+// http://wg21.link/LWG2447 gives implementors freedom to reject const or volatile types in `std::allocator`.
 
 #include <memory>
 
-std::allocator<volatile int> A1; // expected-error@*:* {{std::allocator does not support volatile types}}
-std::allocator<const volatile int> A2; // expected-error@*:* {{std::allocator does not support volatile types}}
+std::allocator<const int> A1; // expected-error@*:* {{std::allocator does not support const types}}
+std::allocator<volatile int> A2; // expected-error@*:* {{std::allocator does not support volatile types}}
diff --git a/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp b/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
index ee1405f1f889d..6a31fb90e4da2 100644
--- a/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
+++ b/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
@@ -205,9 +205,6 @@ void test()
     test_not_const<std::array<      volatile int, 1>>();
     test_false    <std::array<const volatile int, 1>>();
     test_true     <std::deque<               int>>();
-#ifdef _LIBCPP_VERSION
-    test_true     <std::deque<const          int>>();
-#endif // _LIBCPP_VERSION
     test_true     <std::forward_list<int>>();
     test_true     <std::list<int>>();
     test_true     <std::vector<int>>();
@@ -226,9 +223,6 @@ void test()
 
     // Container adaptors
     test_true     <std::stack<               int>>();
-#ifdef _LIBCPP_VERSION
-    test_true     <std::stack<const          int>>();
-#endif // _LIBCPP_VERSION
     test_true     <std::queue<int>>();
     test_true     <std::priority_queue<int>>();
 
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp
index 6e6ff1f2d1344..a278bc41ef761 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator.ctor.pass.cpp
@@ -37,12 +37,12 @@ TEST_CONSTEXPR_CXX20 bool test() {
 
 int main(int, char**) {
   test<char>();
-  test<char const>();
+  test<int>();
   test<void>();
 
 #if TEST_STD_VER > 17
   static_assert(test<char>());
-  static_assert(test<char const>());
+  static_assert(test<int>());
   static_assert(test<void>());
 #endif
   return 0;
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp
index a095ca102491e..69c6595c98645 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator.dtor.pass.cpp
@@ -26,15 +26,9 @@ int main(int, char**)
 {
     test<int>();
     test<void>();
-#ifdef _LIBCPP_VERSION // extension
-    test<int const>();
-#endif // _LIBCPP_VERSION
 
     static_assert(test<int>());
     static_assert(test<void>());
-#ifdef _LIBCPP_VERSION // extension
-    static_assert(test<int const>());
-#endif // _LIBCPP_VERSION
 
     return 0;
 }
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp
index fbbb334fea0fd..34a89e8be8591 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.constexpr.size.verify.cpp
@@ -34,5 +34,4 @@ constexpr bool test()
 
 void f() {
     static_assert(test<double>()); // expected-error {{static assertion expression is not an integral constant expression}}
-    LIBCPP_STATIC_ASSERT(test<const double>()); // expected-error {{static assertion expression is not an integral constant expression}}
 }
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp
index 1913a0e0dcc8d..2b11bd7f48dd7 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator.members/allocate.size.pass.cpp
@@ -45,7 +45,6 @@ void test()
 int main(int, char**)
 {
     test<double>();
-    LIBCPP_ONLY(test<const double>());
 
   return 0;
 }
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp
index 917492929ecc2..96ae6427188c0 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp
@@ -35,13 +35,6 @@ void f() {
         typedef std::allocator<char>::const_reference ConstReference;   // expected-warning {{'const_reference' is deprecated}}
         typedef std::allocator<char>::rebind<int>::other Rebind;        // expected-warning {{'rebind<int>' is deprecated}}
     }
-    {
-        typedef std::allocator<char const>::pointer Pointer;                  // expected-warning {{'pointer' is deprecated}}
-        typedef std::allocator<char const>::const_pointer ConstPointer;       // expected-warning {{'const_pointer' is deprecated}}
-        typedef std::allocator<char const>::reference Reference;              // expected-warning {{'reference' is deprecated}}
-        typedef std::allocator<char const>::const_reference ConstReference;   // expected-warning {{'const_reference' is deprecated}}
-        typedef std::allocator<char const>::rebind<int>::other Rebind;        // expected-warning {{'rebind<int>' is deprecated}}
-    }
     {
         typedef std::allocator<void>::pointer Pointer;                  // expected-warning {{'pointer' is deprecated}}
         typedef std::allocator<void>::const_pointer ConstPointer;       // expected-warning {{'const_pointer' is deprecated}}
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp
index 7085a1d3fc602..581bdced36a0d 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp
@@ -61,8 +61,5 @@ void test() {
 
 int main(int, char**) {
     test<char>();
-#ifdef _LIBCPP_VERSION
-    test<char const>(); // extension
-#endif
     return 0;
 }
diff --git a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp
index 2fb7a60c9a88f..e8c48439b9f46 100644
--- a/libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp
+++ b/libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp
@@ -39,6 +39,6 @@ void check()
 
 void f() {
     check<char>();
-    check<char const>();
+    check<int>();
     check<voi...
[truncated]

zibi2 · 2024-06-21T18:58:01Z

We are fine with this patch. Thank you for giving us grace period.

cjdb

Thank you for providing the opt-out mechanism!

libcxx/docs/ReleaseNotes/19.rst

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libnetd_server Change-Id: I1e97b0685fd94dc11f1c58c7fa05e1dd140d8172

In llvm/llvm-project#96319, libc++ removed the `allocator<const T>` extension. This change removes most uses from the Fuchsia build and suppresses the remaining ones. Bug: 349734097 Change-Id: I31b1a29125b8175ab1cba5c89345d391e7bda404 Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1072789 Fuchsia-Auto-Submit: Petr Hosek <phosek@google.com> Reviewed-by: Jacob Rutherford <jruthe@google.com> Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com> Reviewed-by: Roland McGrath <mcgrathr@google.com> Reviewed-by: Ian McKellar <ianloic@google.com>

In llvm/llvm-project#96319, libc++ removed the `allocator<const T>` extension. This change removes most uses from the Fuchsia build and suppresses the remaining ones. Original-Bug: 349734097 Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1072789 Original-Revision: 6844bacfeec5c5739d3c7c31cc051c4ceccb1408 GitOrigin-RevId: e5fc8ae7ee56e3cf7c51f9eb2acbe2c926d42130 Change-Id: If6baf78af711f98a04c7fee18cd1225c519d6347

This effort has quite a history: - This was first attempted in 2022 via bed3240, which broke std::shared_ptr<T const> and caused the change to be reverted in 9138666. - We then re-attempted landing the change in 276ca87 after fixing std::shared_ptr, but reports were made that this broke code en masse within Google. This led to the patch being reverted again in a54d028 with the goal to land this again with a migration path for vendors. This patch re-lands the removal while providing a migration path for vendors by providing the `_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST` macro. This macro will be honored for the LLVM 19 release and will be removed after that, at which point allocator<const T> will be removed unconditionally. Fixes llvm#73665

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libaapt2 Change-Id: Ic712f8c844b05687948162e5d080af3726b322f6

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libfs_mgr Change-Id: Ic7f50453f05293b7684be22393d6e5871e493983

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m bootstat Change-Id: Id338f439aa4caf8c9f3c6fc15faef19b1edc4368

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libstagefright_bufferpool@2.0.1 Change-Id: If562374c45fa5a48b1cf45007b6264937014dea5

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libstagefright Change-Id: If6dd5edb7a6c83d5e3f37e21fd8fdfe41f1093cc

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libcameraservice Change-Id: Ib3ae6b55c4e95cd458e190511a59e8d0459cf16a

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libnetdutils Change-Id: I0b0eb07a6c95b4781ad04a82068bd33aef68e33b

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libstagefright_aidl_bufferpool2 Change-Id: I6491377d6275c5d18cd91b40184d6f05cff7cb9a

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libdumputils Change-Id: Ie673d1f16ebe25050e4f04a2fce797cb6a98f2d9

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m librenderengine Change-Id: I4c0f5adb94415777f832217bc8115e04de6186c5

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libcompositionengine Change-Id: I359350a298fc9a59c0ca925a36f753ac3fb3b64e

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m android.hardware.confirmationui-lib.cuttlefish Test: trusty/vendor/google/aosp/scripts/build.py qemu-generic-arm64-test-debug Change-Id: I455844e2b09cfee34646bc3693867c7c1ff597e3

llvm/llvm-project#96319 removed the support of containers with const qualified element type in libc++. This patch removes the const from a container to fix the build issue. Bug: 354872193 Change-Id: I57394ca2ba32cb6b340651d94eec5fe047cd5bed Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1087412 Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com> Reviewed-by: Marie Janssen <jamuraa@google.com> Fuchsia-Auto-Submit: Gulfem Savrun Yeniceri <gulfem@google.com>

llvm/llvm-project#96319 removed the support of containers with const qualified element type in libc++. This patch removes the const from a container to fix the build issue. Original-Bug: 354872193 Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1087412 Original-Revision: 6044901600a19eeb80fce0fa2f8d492dc0e2cc9a GitOrigin-RevId: 079bb67b8a4f02027e0380cbc4479a0a8ea49c5a Change-Id: I2db7b655cc7dcba15a8de8e059b2c653321ec40a

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libnetdutils Change-Id: I0b0eb07a6c95b4781ad04a82068bd33aef68e33b Former-commit-id: b2d7582274fe30b9a70a9bda24b105fe970e13cf

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m libfs_mgr Change-Id: Ic7f50453f05293b7684be22393d6e5871e493983

A container of const T uses std::allocator<const T>, which was an undocumented libc++ extension that has been removed. See llvm/llvm-project#96319. Bug: 349681543 Test: m bootstat Change-Id: Id338f439aa4caf8c9f3c6fc15faef19b1edc4368

ldionne added this to the LLVM 19.X Release milestone Jun 21, 2024

ldionne requested a review from a team as a code owner June 21, 2024 15:20

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Jun 21, 2024

Fix missed tests

1fcf15d

cjdb approved these changes Jun 24, 2024

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libcxx/docs/ReleaseNotes/19.rst Outdated Show resolved Hide resolved

ldionne added 2 commits June 24, 2024 17:20

Mention clang-tidy in release note

3123b56

Fix test

9f4a531

ldionne merged commit eb12d9b into llvm:main Jun 25, 2024
51 of 58 checks passed

ldionne deleted the review/remove-allocator-const-extension branch June 25, 2024 14:19

nico mentioned this pull request Jul 12, 2024

Reapply "[libc++] Optimize vector growing of trivially relocatable types" #80558

Merged

StephanTLavavej mentioned this pull request Jul 25, 2024

llvm-project Mid-Year Update microsoft/STL#4862

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[libc++] Remove the allocator<const T> extension #96319

[libc++] Remove the allocator<const T> extension #96319

ldionne commented Jun 21, 2024

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[libc++] Remove the allocator<const T> extension #96319

[libc++] Remove the allocator<const T> extension #96319

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