[libc++] Remove macros for keeping std::allocator members and void specialization after C++20 (#85806)

Fixes #75975.

Remove `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS` for the LLVM 19
release, it was previously marked as deprecated in LLVM 18.

I believe that
`_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION` was only
used by Google in conjunction with
`_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS`.

Removing both macros together should not cause any issues in practice,
even though we did not announce the removal of
`_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION` before.

Author: ilya-biryukov

libcxx/docs/ReleaseNotes/19.rst

@@ -70,7 +70,8 @@ Deprecations and Removals
 - The ``_LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT`` macro that changed the behavior for narrowing conversions
   in ``std::variant`` has been removed in LLVM 19.
 
-- TODO: The ``_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS`` macro has been removed in LLVM 19.
+- The ``_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS`` and ``_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION``
+  macros have been removed in LLVM 19.
 
 - TODO: The ``_LIBCPP_ENABLE_CXX17_REMOVED_FEATURES`` and ``_LIBCPP_ENABLE_CXX20_REMOVED_FEATURES`` macros have
   been removed in LLVM 19. C++17 and C++20 removed features can still be re-enabled individually.

libcxx/docs/UsingLibcxx.rst

@@ -244,18 +244,6 @@ C++20 Specific Configuration Macros
   This macro is deprecated and will be removed in LLVM-19. Use the
   individual macros listed below.
 
-**_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS**:
-  This macro is used to re-enable redundant members of `allocator<T>`,
-  including `pointer`, `reference`, `rebind`, `address`, `max_size`,
-  `construct`, `destroy`, and the two-argument overload of `allocate`.
-  This macro has been deprecated and will be removed in LLVM-19.
-
-**_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION**:
-  This macro is used to re-enable the library-provided specializations of
-  `allocator<void>` and `allocator<const void>`.
-  Use it in conjunction with `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS`
-  to ensure that removed members of `allocator<void>` can be accessed.
-
 **_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS**:
   This macro is used to re-enable the `argument_type`, `result_type`,
   `first_argument_type`, and `second_argument_type` members of class

libcxx/include/__config

@@ -1238,8 +1238,6 @@ __sanitizer_verify_double_ended_contiguous_container(const void*, const void*, c
 #  endif // _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES
 
 #  if defined(_LIBCPP_ENABLE_CXX20_REMOVED_FEATURES)
-#    define _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
-#    define _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_NEGATORS
 #    define _LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR

libcxx/include/__memory/allocator.h

@@ -31,18 +31,12 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 template <class _Tp>
 class allocator;
 
-#if defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) && !defined(_LIBCPP_DISABLE_DEPRECATION_WARNINGS)
-#  pragma clang deprecated(                                                                                            \
-      _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS,                                                                  \
-      "_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS is deprecated in LLVM 18 and will be removed in LLVM 19")
-#endif
-
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION)
+#if _LIBCPP_STD_VER <= 17
 // These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17.
 // Specializing allocator<void> is deprecated, but not using it.
 template <>
 class _LIBCPP_TEMPLATE_VIS allocator<void> {
-#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
+#  if _LIBCPP_STD_VER <= 17
 
 public:
   _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer;
@@ -58,7 +52,7 @@ class _LIBCPP_TEMPLATE_VIS allocator<void> {
 
 template <>
 class _LIBCPP_TEMPLATE_VIS allocator<const void> {
-#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
+#  if _LIBCPP_STD_VER <= 17
 
 public:
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer;
@@ -141,7 +135,7 @@ class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::v
   }
 
   // C++20 Removed members
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
+#if _LIBCPP_STD_VER <= 17
   _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
   _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference;
@@ -221,7 +215,7 @@ class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
   }
 
   // C++20 Removed members
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
+#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;

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/address.cxx2a.pass.cpp renamed to libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/address.cxx20.pass.cpp

@@ -12,11 +12,9 @@
 // pointer address(reference x) const;
 // const_pointer address(const_reference x) const;
 
-//  In C++20, parts of std::allocator<T> have been removed.
-//  However, for backwards compatibility, if _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
-//  is defined before including <memory>, then removed members will be restored.
+// Removed in C++20, deprecated in C++17.
 
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
+// REQUIRES: c++03 || c++11 || c++14 || c++17
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
 
 #include <memory>
@@ -25,25 +23,22 @@
 #include "test_macros.h"
 
 template <class T>
-void test_address()
-{
-    T* tp = new T();
-    const T* ctp = tp;
-    const std::allocator<T> a;
-    assert(a.address(*tp) == tp);
-    assert(a.address(*ctp) == tp);
-    delete tp;
+void test_address() {
+  T* tp        = new T();
+  const T* ctp = tp;
+  const std::allocator<T> a;
+  assert(a.address(*tp) == tp);
+  assert(a.address(*ctp) == tp);
+  delete tp;
 }
 
-struct A
-{
-    void operator&() const {}
+struct A {
+  void operator&() const {}
 };
 
-int main(int, char**)
-{
-    test_address<int>();
-    test_address<A>();
+int main(int, char**) {
+  test_address<int>();
+  test_address<A>();
 
   return 0;
 }

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/address.cxx20.verify.cpp

@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// allocator:
+// pointer address(reference x) const;
+// const_pointer address(const_reference x) const;
+
+// In C++20, parts of std::allocator<T> have been removed.
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+
+template <class T>
+void test_address() {
+  T* tp        = new T();
+  const T* ctp = tp;
+  const std::allocator<T> a;
+  assert(a.address(*tp) == tp);  // expected-error 2 {{no member}}
+  assert(a.address(*ctp) == tp); // expected-error 2 {{no member}}
+  delete tp;
+}
+
+struct A {
+  void operator&() const {}
+};
+
+int main(int, char**) {
+  test_address<int>();
+  test_address<A>();
+
+  return 0;
+}

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/address.depr_in_cxx17.verify.cpp

@@ -14,9 +14,7 @@
 
 // Deprecated in C++17
 
-// UNSUPPORTED: c++03, c++11, c++14
-
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS -Wno-deprecated-pragma
+// REQUIRES: c++17
 
 #include <memory>
 

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/allocate.cxx2a.pass.cpp renamed to libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/allocate.cxx20.pass.cpp

@@ -11,17 +11,18 @@
 // allocator:
 // T* allocate(size_t n, const void* hint);
 
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
+// Removed in C++20, deprecated in C++17.
+
+// REQUIRES: c++03 || c++11 || c++14 || c++17
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
 
 #include <memory>
 #include <cassert>
-#include <cstddef>       // for std::max_align_t
+#include <cstddef> // for std::max_align_t
 
 #include "test_macros.h"
 #include "count_new.h"
 
-
 #ifdef TEST_HAS_NO_ALIGNED_ALLOCATION
 static const bool UsingAlignedNew = false;
 #else
@@ -36,7 +37,6 @@ static const std::size_t MaxAligned = std::alignment_of<std::max_align_t>::value
 
 static const std::size_t OverAligned = MaxAligned * 2;
 
-
 template <std::size_t Align>
 struct TEST_ALIGNAS(Align) AlignedType {
   char data;
@@ -48,19 +48,18 @@ struct TEST_ALIGNAS(Align) AlignedType {
 template <std::size_t Align>
 int AlignedType<Align>::constructed = 0;
 
-
 template <std::size_t Align>
 void test_aligned() {
   typedef AlignedType<Align> T;
   T::constructed = 0;
   globalMemCounter.reset();
   std::allocator<T> a;
   const bool IsOverAlignedType = Align > MaxAligned;
-  const bool ExpectAligned = IsOverAlignedType && UsingAlignedNew;
+  const bool ExpectAligned     = IsOverAlignedType && UsingAlignedNew;
   {
-    globalMemCounter.last_new_size = 0;
+    globalMemCounter.last_new_size  = 0;
     globalMemCounter.last_new_align = 0;
-    T* ap2 = a.allocate(11, (const void*)5);
+    T* ap2                          = a.allocate(11, (const void*)5);
     DoNotOptimize(ap2);
     assert(globalMemCounter.checkOutstandingNewEq(1));
     assert(globalMemCounter.checkNewCalledEq(1));
@@ -80,14 +79,14 @@ void test_aligned() {
 }
 
 int main(int, char**) {
-    test_aligned<1>();
-    test_aligned<2>();
-    test_aligned<4>();
-    test_aligned<8>();
-    test_aligned<16>();
-    test_aligned<MaxAligned>();
-    test_aligned<OverAligned>();
-    test_aligned<OverAligned * 2>();
+  test_aligned<1>();
+  test_aligned<2>();
+  test_aligned<4>();
+  test_aligned<8>();
+  test_aligned<16>();
+  test_aligned<MaxAligned>();
+  test_aligned<OverAligned>();
+  test_aligned<OverAligned * 2>();
 
   return 0;
 }

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/allocate.cxx20.verify.cpp

@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+// 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>
+
+// allocator:
+// T* allocate(size_t n, const void* hint);
+
+// Removed in C++20.
+
+#include <memory>
+
+void f() {
+  std::allocator<int> a;
+  a.allocate(3, nullptr); // expected-error {{too many arguments to function call}}
+}

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/allocate.cxx2a.verify.cpp

@@ -13,9 +13,7 @@
 
 // Deprecated in C++17
 
-// UNSUPPORTED: c++03, c++11, c++14
-
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS -Wno-deprecated-pragma
+// REQUIRES: c++17
 
 #include <memory>