Revert "[libcxx][iterator] adds std::indirectly_readable and std::indirectly_writable"

This reverts commit 0473318 which was
failing for multiple people.

Author: davezarzycki

libcxx/include/__iterator/concepts.h

@@ -12,10 +12,6 @@
 
 #include <__config>
 #include <concepts>
-#include <__iterator/iter_move.h>
-#include <__iterator/incrementable_traits.h>
-#include <__iterator/iterator_traits.h>
-#include <__iterator/readable_traits.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -28,36 +24,18 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if !defined(_LIBCPP_HAS_NO_RANGES)
 
-// clang-format off
+template<class _Tp>
+using __with_reference = _Tp&;
 
-// [iterator.concept.readable]
-template<class _In>
-concept __indirectly_readable_impl =
-  requires(const _In __in) {
-    typename iter_value_t<_In>;
-    typename iter_reference_t<_In>;
-    typename iter_rvalue_reference_t<_In>;
-    { *__in } -> same_as<iter_reference_t<_In> >;
-    { ranges::iter_move(__in) } -> same_as<iter_rvalue_reference_t<_In> >;
-  } &&
-  common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
-  common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
-  common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;
+template<class _Tp>
+concept __referenceable = requires {
+  typename __with_reference<_Tp>;
+};
 
-template<class _In>
-concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In> >;
-
-// [iterator.concept.writable]
-template<class _Out, class _Tp>
-concept indirectly_writable =
-  requires(_Out&& __o, _Tp&& __t) {
-    *__o = _VSTD::forward<_Tp>(__t);                        // not required to be equality-preserving
-    *_VSTD::forward<_Out>(__o) = _VSTD::forward<_Tp>(__t);  // not required to be equality-preserving
-    const_cast<const iter_reference_t<_Out>&&>(*__o) = _VSTD::forward<_Tp>(__t);                       // not required to be equality-preserving
-    const_cast<const iter_reference_t<_Out>&&>(*_VSTD::forward<_Out>(__o)) = _VSTD::forward<_Tp>(__t); // not required to be equality-preserving
-  };
-
-// clang-format on
+template<class _Tp>
+concept __dereferenceable = requires(_Tp& __t) {
+  { *__t } -> __referenceable; // not required to be equality-preserving
+};
 
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
 

libcxx/include/__iterator/incrementable_traits.h

@@ -11,7 +11,7 @@
 #define _LIBCPP___ITERATOR_INCREMENTABLE_TRAITS_H
 
 #include <__config>
-#include <concepts>
+#include <__iterator/concepts.h>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

libcxx/include/__iterator/iter_move.h

@@ -11,7 +11,7 @@
 #define _LIBCPP___ITERATOR_ITER_MOVE_H
 
 #include <__config>
-#include <__iterator/iterator_traits.h>
+#include <__iterator/concepts.h>
 #include <concepts> // __class_or_enum
 #include <type_traits>
 #include <utility>

libcxx/include/__iterator/iterator_traits.h

@@ -27,23 +27,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if !defined(_LIBCPP_HAS_NO_RANGES)
 
-template <class _Tp>
-using __with_reference = _Tp&;
-
-template <class _Tp>
-concept __referenceable = requires {
-  typename __with_reference<_Tp>;
-};
-
-template <class _Tp>
-concept __dereferenceable = requires(_Tp& __t) {
-  { *__t } -> __referenceable; // not required to be equality-preserving
-};
-
 // [iterator.traits]
 template<__dereferenceable _Tp>
 using iter_reference_t = decltype(*declval<_Tp&>());
-
 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
 
 template <class _Iter>

libcxx/include/__iterator/readable_traits.h

@@ -11,8 +11,7 @@
 #define _LIBCPP___ITERATOR_READABLE_TRAITS_H
 
 #include <__config>
-#include <concepts>
-#include <type_traits>
+#include <__iterator/concepts.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header

libcxx/include/iterator

@@ -43,15 +43,6 @@ template<dereferenceable T>
   requires ...
 using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<T&>())); // since C++20
 
-// [iterator.concepts], iterator concepts
-// [iterator.concept.readable], concept indirectly_­readable
-template<class In>
-  concept indirectly_readable = see below;                // since C++20
-
-// [iterator.concept.writable], concept indirectly_­writable
-template<class Out, class T>
-  concept indirectly_writable = see below;                // since C++20
-
 template<class Category, class T, class Distance = ptrdiff_t,
          class Pointer = T*, class Reference = T&>
 struct iterator