[libc++][spaceship] P1614R2: Removed ops from `memory_resource`, `polymorphic_allocator`

[H-G-Hristov]

Summary

Implements parts of P1614R2

• Removed ops from memory_resource
• Removed ops from polymorphic_allocator

[H-G-Hristov]

Rebased

[H-G-Hristov]

Rebased

[Mordante]

LGTM, thanks to the set of operator!= removal patches. I'm really happy this paper is moving to its conclusion!

[H-G-Hristov]

In D152629#4411982, @Mordante wrote:

LGTM, thanks to the set of operator!= removal patches. I'm really happy this paper is moving to its conclusion!

Thank you for the review. I'll try to submit more patches daily next week.

libcxx/docs/Status/SpaceshipProjects.csv

 | `variant <https://reviews.llvm.org/D131372>`_",None,Kent Ross,|Complete|
 "| `[template.bitset] <https://wg21.link/template.bitset>`_
 | `[bitset.members] <https://wg21.link/bitset.members>`_","| remove ops `bitset <https://reviews.llvm.org/D152611>`_",None,Hristo Hristov,|In Progress|
 | `[memory.syn] <https://wg21.link/memory.syn>`_,|,None,Unassigned,|Not Started|
 | `[allocator.globals] <https://wg21.link/allocator.globals>`_,| remove ops `allocator <https://reviews.llvm.org/D152612>`_,None,Hristo Hristov,|In Progress|
 | `[unique.ptr.special] <https://wg21.link/unique.ptr.special>`_,| `unique_ptr <https://reviews.llvm.org/D130838>`_,[comparisons.three.way],Adrian Vogelsgesang,|Complete|
 | `[util.smartptr.shared.cmp] <https://wg21.link/util.smartptr.shared.cmp>`_,| `shared_ptr <https://reviews.llvm.org/D130852>`_,[comparisons.three.way],Adrian Vogelsgesang,|Complete|
 | `[mem.res.syn] <https://wg21.link/mem.res.syn>`_,|,None,Unassigned,|Not Started|
-| `[mem.res.eq] <https://wg21.link/mem.res.eq>`_,| remove ops `memory_resource`,None,Unassigned,|Not Started|
-| `[mem.poly.allocator.eq] <https://wg21.link/mem.poly.allocator.eq>`_,| remove ops `polymorphic_allocator`,None,Unassigned,|Not Started|
+"| `[mem.res.eq] <https://wg21.link/mem.res.eq>`_
+| `[mem.poly.allocator.eq] <https://wg21.link/mem.poly.allocator.eq>`_","| remove ops `memory_resource <https://reviews.llvm.org/>`_
+| remove ops `polymorphic_allocator <https://reviews.llvm.org/>`_",None,Hristo Hristov,|Complete|
 "| `[allocator.adaptor.syn] <https://wg21.link/allocator.adaptor.syn>`_
 | `[scoped.adaptor.operators] <https://wg21.link/scoped.adaptor.operators>`_",| remove ops `scoped_allocator_adaptor`,None,Unassigned,|Not Started|
 "| `[functional.syn] <https://wg21.link/functional.syn>`_
 | `[range.cmp] <https://wg21.link/range.cmp>`_
 | `[func.wrap.func] <https://wg21.link/func.wrap.func>`_
 | `[func.wrap.func.nullptr] <https://wg21.link/func.wrap.func.nullptr>`_",| remove ops `function`,None,Unassigned,|Not Started|
 | `[meta.unary.prop] <https://wg21.link/meta.unary.prop>`_,| replaced by `issue LWG3354 <https://wg21.link/LWG3354>`_,None,Unassigned,|Nothing To Do|
 | `[meta.trans.other] <https://wg21.link/meta.trans.other>`_,|,None,Unassigned,|Not Started|

libcxx/include/__memory_resource/memory_resource.h

 };
 
 // [mem.res.eq]
 
 inline _LIBCPP_HIDE_FROM_ABI bool operator==(const memory_resource& __lhs, const memory_resource& __rhs) noexcept {
   return &__lhs == &__rhs || __lhs.is_equal(__rhs);
 }
 
+#  if _LIBCPP_STD_VER <= 17
+
 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const memory_resource& __lhs, const memory_resource& __rhs) noexcept {
   return !(__lhs == __rhs);
 }
 
+#  endif
+
 // [mem.res.global]
 
 [[__gnu__::__returns_nonnull__]] _LIBCPP_FUNC_VIS memory_resource* get_default_resource() noexcept;
 [[__gnu__::__returns_nonnull__]] _LIBCPP_FUNC_VIS memory_resource* set_default_resource(memory_resource*) noexcept;
 [[using __gnu__: __returns_nonnull__, __const__]] _LIBCPP_FUNC_VIS memory_resource* new_delete_resource() noexcept;
 [[using __gnu__: __returns_nonnull__, __const__]] _LIBCPP_FUNC_VIS memory_resource* null_memory_resource() noexcept;
 
 } // namespace pmr
 
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_STD_VER >= 17
 
 #endif // _LIBCPP___MEMORY_RESOURCE_MEMORY_RESOURCE_H

libcxx/include/__memory_resource/polymorphic_allocator.h

 // [mem.poly.allocator.eq]
 
 template <class _Tp, class _Up>
 inline _LIBCPP_HIDE_FROM_ABI bool
 operator==(const polymorphic_allocator<_Tp>& __lhs, const polymorphic_allocator<_Up>& __rhs) noexcept {
   return *__lhs.resource() == *__rhs.resource();
 }
 
+#  if _LIBCPP_STD_VER <= 17
+
 template <class _Tp, class _Up>
 inline _LIBCPP_HIDE_FROM_ABI bool
 operator!=(const polymorphic_allocator<_Tp>& __lhs, const polymorphic_allocator<_Up>& __rhs) noexcept {
   return !(__lhs == __rhs);
 }
 
+#  endif
+
 } // namespace pmr
 
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_STD_VER >= 17
 
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___MEMORY_RESOURCE_POLYMORPHIC_ALLOCATOR_H

libcxx/include/memory_resource

 
 namespace std::pmr {
 
   class memory_resource;
 
   bool operator==(const memory_resource& a,
                   const memory_resource& b) noexcept;
   bool operator!=(const memory_resource& a,
-                  const memory_resource& b) noexcept;
+                  const memory_resource& b) noexcept;           // removed in C++20
 
   template <class Tp> class polymorphic_allocator;
 
   template <class T1, class T2>
   bool operator==(const polymorphic_allocator<T1>& a,
                   const polymorphic_allocator<T2>& b) noexcept;
   template <class T1, class T2>
   bool operator!=(const polymorphic_allocator<T1>& a,
-                  const polymorphic_allocator<T2>& b) noexcept;
+                  const polymorphic_allocator<T2>& b) noexcept; // removed in C++20
 
   // Global memory resources
   memory_resource* set_default_resource(memory_resource* r) noexcept;
   memory_resource* get_default_resource() noexcept;
   memory_resource* new_delete_resource() noexcept;
   memory_resource* null_memory_resource() noexcept;
 
   // Pool resource classes