[libc++] Un-deprecate and un-remove some members of std::allocator

This implements the part of P0619R4 related to the default allocator.
This is incredibly important, since otherwise there is an ABI break
between C++17 and C++20 w.r.t. the default allocator's size_type on
platforms where std::size_t is not the same as std::make_unsigned<std::ptrdiff_t>.

libcxx/include/memory

@@ -115,8 +115,8 @@ template <class T>
 class allocator
 {
 public:
-    typedef size_t    size_type;                         // deprecated in C++17, removed in C++20
+    typedef size_t    size_type;
-    typedef ptrdiff_t difference_type;                   // deprecated in C++17, removed in C++20
+    typedef ptrdiff_t difference_type;
     typedef T*        pointer;                           // deprecated in C++17, removed in C++20
     typedef const T*  const_pointer;                     // deprecated in C++17, removed in C++20
     typedef typename add_lvalue_reference<T>::type
@@ -1748,9 +1748,9 @@ template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator
 {
 public:
+    typedef size_t     size_type;
+    typedef ptrdiff_t  difference_type;
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
-    _LIBCPP_DEPRECATED_IN_CXX17 typedef size_t     size_type;
-    _LIBCPP_DEPRECATED_IN_CXX17 typedef ptrdiff_t  difference_type;
     _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp*       pointer;
     _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
     _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp&       reference;
@@ -1816,9 +1816,9 @@ template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
 {
 public:
+    typedef size_t     size_type;
+    typedef ptrdiff_t  difference_type;
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
-    _LIBCPP_DEPRECATED_IN_CXX17 typedef size_t     size_type;
-    _LIBCPP_DEPRECATED_IN_CXX17 typedef ptrdiff_t  difference_type;
     _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_types.cxx2a.pass.cpp

@@ -8,7 +8,8 @@
 
 // <memory>
 
-// check nested types:
+// Check that the following types are provided regardless of the Standard when
+// we request them from libc++.
 
 // template <class T>
 // class allocator

libcxx/test/libcxx/depr/depr.default.allocator/allocator_void.cxx2a.pass.cpp

@@ -8,6 +8,9 @@
 
 // <memory>
 
+// Check that the following member types of allocator<void> are provided
+// regardless of the Standard when we request them from libc++.
+
 // template <>
 // class allocator<void>
 // {

libcxx/test/std/utilities/memory/default.allocator/allocator_types.deprecated_in_cxx17.verify.cpp

@@ -8,14 +8,12 @@
 
 // <memory>
 
-// check nested types:
+// Check that the following nested types are deprecated in C++17:
 
 // template <class T>
 // class allocator
 // {
 // public:
-//     typedef size_t                                size_type;
-//     typedef ptrdiff_t                             difference_type;
 //     typedef T*                                           pointer;
 //     typedef const T*                                     const_pointer;
 //     typedef typename add_lvalue_reference<T>::type       reference;
@@ -25,28 +23,27 @@
 // ...
 // };
 
-// Deprecated in C++17
+// REQUIRES: c++17
-
-// UNSUPPORTED: c++03, c++11, c++14
 
 // Clang 6 does not handle the deprecated attribute on template members properly,
 // so the rebind<int> check below fails.
 // UNSUPPORTED: clang-6
 
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
-
 #include <memory>
 #include "test_macros.h"
 
 int main(int, char**)
 {
-    typedef std::allocator<char>::size_type AST;          // expected-warning {{'size_type' is deprecated}}
-    typedef std::allocator<char>::difference_type ADT;    // expected-warning {{'difference_type' is deprecated}}
     typedef std::allocator<char>::pointer AP;             // expected-warning {{'pointer' is deprecated}}
     typedef std::allocator<char>::const_pointer ACP;      // expected-warning {{'const_pointer' is deprecated}}
     typedef std::allocator<char>::reference AR;           // expected-warning {{'reference' is deprecated}}
     typedef std::allocator<char>::const_reference ACR;    // expected-warning {{'const_reference' is deprecated}}
     typedef std::allocator<char>::rebind<int>::other ARO; // expected-warning {{'rebind<int>' is deprecated}}
 
+    typedef std::allocator<char const>::pointer AP2;             // expected-warning {{'pointer' is deprecated}}
+    typedef std::allocator<char const>::const_pointer ACP2;      // expected-warning {{'const_pointer' is deprecated}}
+    typedef std::allocator<char const>::reference AR2;           // expected-warning {{'reference' is deprecated}}
+    typedef std::allocator<char const>::const_reference ACR2;    // expected-warning {{'const_reference' is deprecated}}
+    typedef std::allocator<char const>::rebind<int>::other ARO2; // expected-warning {{'rebind<int>' is deprecated}}
     return 0;
 }

libcxx/test/std/utilities/memory/default.allocator/allocator_types.pass.cpp

@@ -8,12 +8,14 @@
 
 // <memory>
 
-// check nested types:
+// Check that the nested types of std::allocator are provided:
 
 // template <class T>
 // class allocator
 // {
 // public:
+//     typedef size_t    size_type;
+//     typedef ptrdiff_t difference_type;
 //     typedef T         value_type;
 //
 //     typedef true_type propagate_on_container_move_assignment;
@@ -27,21 +29,25 @@
 
 #include "test_macros.h"
 
+template <typename T, typename U>
+void check()
+{
+    static_assert((std::is_same<typename std::allocator<T>::size_type, std::size_t>::value), "");
+    static_assert((std::is_same<typename std::allocator<T>::difference_type, std::ptrdiff_t>::value), "");
+    static_assert((std::is_same<typename std::allocator<T>::value_type, T>::value), "");
+    static_assert((std::is_same<typename std::allocator<T>::propagate_on_container_move_assignment, std::true_type>::value), "");
+    static_assert((std::is_same<typename std::allocator<T>::is_always_equal, std::true_type>::value), "");
+
+    std::allocator<T> a;
+    std::allocator<T> a2 = a;
+    a2 = a;
+    std::allocator<U> a3 = a2;
+    (void)a3;
+}
+
 int main(int, char**)
 {
-    static_assert((std::is_same<std::allocator<char>::value_type, char>::value), "");
+    check<char, int>();
-
+    check<char const, int const>();
-    static_assert((std::is_same<std::allocator<char>::propagate_on_container_move_assignment, std::true_type>::value), "");
-    LIBCPP_STATIC_ASSERT((std::is_same<std::allocator<const char>::propagate_on_container_move_assignment, std::true_type>::value), "");
-
-    static_assert((std::is_same<std::allocator<char>::is_always_equal, std::true_type>::value), "");
-    LIBCPP_STATIC_ASSERT((std::is_same<std::allocator<const char>::is_always_equal, std::true_type>::value), "");
-
-    std::allocator<char> a;
-    std::allocator<char> a2 = a;
-    a2 = a;
-    std::allocator<int> a3 = a2;
-    ((void)a3);
-
     return 0;
 }

libcxx/test/std/utilities/memory/default.allocator/allocator_types.removed_in_cxx20.verify.cpp

@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// 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>
+
+// Check that the following nested types are removed in C++20:
+
+// template <class T>
+// class allocator
+// {
+// public:
+//     typedef T*                                           pointer;
+//     typedef const T*                                     const_pointer;
+//     typedef typename add_lvalue_reference<T>::type       reference;
+//     typedef typename add_lvalue_reference<const T>::type const_reference;
+//
+//     template <class U> struct rebind {typedef allocator<U> other;};
+// ...
+// };
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+#include <memory>
+#include "test_macros.h"
+
+template <typename T>
+void check()
+{
+    typedef typename std::allocator<T>::pointer AP;                      // expected-error 2 {{no type named 'pointer'}}
+    typedef typename std::allocator<T>::const_pointer ACP;               // expected-error 2 {{no type named 'const_pointer'}}
+    typedef typename std::allocator<T>::reference AR;                    // expected-error 2 {{no type named 'reference'}}
+    typedef typename std::allocator<T>::const_reference ACR;             // expected-error 2 {{no type named 'const_reference'}}
+    typedef typename std::allocator<T>::template rebind<int>::other ARO; // expected-error 2 {{no member named 'rebind'}}
+}
+
+int main(int, char**)
+{
+    check<char>();
+    check<char const>();
+    return 0;
+}

libcxx/test/std/utilities/memory/default.allocator/allocator_void.deprecated_in_cxx17.verify.cpp

@@ -7,23 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 // <memory>
-//
-// template <>
-// class allocator<void>
-// {
-// public:
-//     typedef void*                                 pointer;
-//     typedef const void*                           const_pointer;
-//     typedef void                                  value_type;
-//
-//     template <class _Up> struct rebind {typedef allocator<_Up> other;};
-// };
-//
-// Deprecated in C++17
 
-// UNSUPPORTED: c++03, c++11, c++14
+// Check that allocator<void> is deprecated in C++17.
 
-// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
+// REQUIRES: c++17
 
 #include <memory>
 #include "test_macros.h"
@@ -33,6 +20,5 @@ int main(int, char**)
     typedef std::allocator<void>::pointer AP;             // expected-warning {{'allocator<void>' is deprecated}}
     typedef std::allocator<void>::const_pointer ACP;      // expected-warning {{'allocator<void>' is deprecated}}
     typedef std::allocator<void>::rebind<int>::other ARO; // expected-warning {{'allocator<void>' is deprecated}}
-
     return 0;
 }

libcxx/www/cxx1z_status.html

@@ -105,7 +105,7 @@
 	<tr><td><a href="https://wg21.link/p0088r3">p0088r3</a></td><td>LWG</td><td>Variant: a type-safe union for C++17</td><td>Oulu</td><td>Complete</td><td>4.0</td></tr>
 	<tr><td><a href="https://wg21.link/p0137r1">p0137r1</a></td><td>CWG</td><td>Core Issue 1776: Replacement of class objects containing reference members</td><td>Oulu</td><td>Complete</td><td>6.0</td></tr>
 	<tr><td><a href="https://wg21.link/p0163r0">p0163r0</a></td><td>LWG</td><td>shared_ptr::weak_type</td><td>Oulu</td><td>Complete</td><td>3.9</td></tr>
-	<tr><td><a href="https://wg21.link/p0174r2">p0174r2</a></td><td>LWG</td><td>Deprecating Vestigial Library Parts in C++17</td><td>Oulu</td><td></td><td></td></tr>
+	<tr><td><a href="https://wg21.link/p0174r2">p0174r2</a></td><td>LWG</td><td>Deprecating Vestigial Library Parts in C++17</td><td>Oulu</td><td>Partial</td><td></td></tr>
 	<tr><td><a href="https://wg21.link/p0175r1">p0175r1</a></td><td>LWG</td><td>Synopses for the C library</td><td>Oulu</td><td></td><td></td></tr>
 	<tr><td><a href="https://wg21.link/p0180r2">p0180r2</a></td><td>LWG</td><td>Reserve a New Library Namespace for Future Standardization</td><td>Oulu</td><td><i>Nothing to do</i></td><td>n/a</td></tr>
 	<tr><td><a href="https://wg21.link/p0181r1">p0181r1</a></td><td>LWG</td><td>Ordered by Default</td><td>Oulu</td><td><i>Removed in Kona</i></td><td>n/a</td></tr>

libcxx/www/cxx2a_status.html

@@ -89,7 +89,7 @@
 	<tr><td><a href="https://wg21.link/P0528R3">P0528R3</a></td><td>CWG</td><td>The Curious Case of Padding Bits, Featuring Atomic Compare-and-Exchange</td><td>Rapperswil</td><td></td><td></td></tr>
 	<tr><td><a href="https://wg21.link/P0542R5">P0542R5</a></td><td>CWG</td><td>Support for contract based programming in C++</td><td>Rapperswil</td><td></td><td></td></tr>
 	<tr><td><a href="https://wg21.link/P0556R3">P0556R3</a></td><td>LWG</td><td>Integral power-of-2 operations</td><td>Rapperswil</td><td>Complete</td><td>9.0</td></tr>
-	<tr><td><a href="https://wg21.link/P0619R4">P0619R4</a></td><td>LWG</td><td>Reviewing Deprecated Facilities of C++17 for C++20</td><td>Rapperswil</td><td></td><td></td></tr>
+	<tr><td><a href="https://wg21.link/P0619R4">P0619R4</a></td><td>LWG</td><td>Reviewing Deprecated Facilities of C++17 for C++20</td><td>Rapperswil</td><td>Partial<br>(only std::allocator part is implemented)</td><td></td></tr>
 	<tr><td><a href="https://wg21.link/P0646R1">P0646R1</a></td><td>LWG</td><td>Improving the Return Value of Erase-Like Algorithms</td><td>Rapperswil</td><td>Complete</td><td>10.0</td></tr>
 	<tr><td><a href="https://wg21.link/P0722R3">P0722R3</a></td><td>CWG</td><td>Efficient sized delete for variable sized classes</td><td>Rapperswil</td><td>Complete</td><td>9.0</td></tr>
 	<tr><td><a href="https://wg21.link/P0758R1">P0758R1</a></td><td>LWG</td><td>Implicit conversion traits and utility functions</td><td>Rapperswil</td><td>Complete</td><td></td></tr>