[gcc r14-3134] libstdc++: Use alias template for iterator_category [PR110970]

[gcc r14-3134] libstdc++: Use alias template for iterator_category [PR110970]

[Jonathan Wakely]

https://gcc.gnu.org/g:9cb2a7c8d54b1f6685bc509a07104c458262cb9f

commit r14-3134-g9cb2a7c8d54b1f6685bc509a07104c458262cb9f
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Aug 10 13:48:48 2023 +0100

    libstdc++: Use alias template for iterator_category [PR110970]
    
    This renames __iterator_category_t to __iter_category_t, for consistency
    with std::iter_value_t, std::iter_difference_t and std::iter_reference_t
    in C++20. Then use __iter_category_t in <bits/stl_iterator.h>, which
    fixes the problem of the missing 'typename' that Clang 15 incorrectly
    still requires.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/110970
            * include/bits/stl_iterator.h (__detail::__move_iter_cat): Use
            __iter_category_t.
            (iterator_traits<common_iterator<I, S>>::_S_iter_cat): Likewise.
            (__detail::__basic_const_iterator_iter_cat): Likewise.
            * include/bits/stl_iterator_base_types.h (__iterator_category_t):
            Rename to __iter_category_t.

Diff:
---
 libstdc++-v3/include/bits/stl_iterator.h            | 17 +++++++++--------
 libstdc++-v3/include/bits/stl_iterator_base_types.h |  6 +++---
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index b22d9a4fdb3a..d5ba05f3e22d 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -103,6 +103,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using __clamp_iter_cat
 	= __conditional_t<derived_from<_Cat, _Limit>, _Limit, _Otherwise>;
 
+    template<typename _Iter, typename _Limit>
+      using __clamped_iter_cat_t
+	= __clamp_iter_cat<__iter_category_t<_Iter>, _Limit>;
+
     template<typename _Tp, typename _Up>
       concept __different_from
 	= !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
@@ -168,8 +172,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 			  random_access_iterator_tag,
 			  bidirectional_iterator_tag>;
       using iterator_category
-	= __detail::__clamp_iter_cat<typename __traits_type::iterator_category,
-				     random_access_iterator_tag>;
+	= __detail::__clamped_iter_cat_t<_Iterator, random_access_iterator_tag>;
       using value_type = iter_value_t<_Iterator>;
       using difference_type = iter_difference_t<_Iterator>;
       using reference = iter_reference_t<_Iterator>;
@@ -1426,12 +1429,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { };
 
     template<typename _Iterator>
-      requires requires { typename iterator_traits<_Iterator>::iterator_category; }
+      requires requires { typename __iter_category_t<_Iterator>; }
       struct __move_iter_cat<_Iterator>
       {
 	using iterator_category
-	  = __clamp_iter_cat<typename iterator_traits<_Iterator>::iterator_category,
-			     random_access_iterator_tag>;
+	  = __clamped_iter_cat_t<_Iterator, random_access_iterator_tag>;
       };
 #endif
   }
@@ -2288,8 +2290,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static auto
       _S_iter_cat()
       {
-	using _Traits = iterator_traits<_It>;
-	if constexpr (requires { requires derived_from<typename _Traits::iterator_category,
+	if constexpr (requires { requires derived_from<__iter_category_t<_It>,
 						       forward_iterator_tag>; })
 	  return forward_iterator_tag{};
 	else
@@ -2615,7 +2616,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     template<forward_iterator _It>
       struct __basic_const_iterator_iter_cat<_It>
-      { using iterator_category = iterator_traits<_It>::iterator_category; };
+      { using iterator_category = __iter_category_t<_It>; };
   } // namespace detail
 
   template<input_iterator _It>
diff --git a/libstdc++-v3/include/bits/stl_iterator_base_types.h b/libstdc++-v3/include/bits/stl_iterator_base_types.h
index 5d2c8b325d9f..841b5eca3ad1 100644
--- a/libstdc++-v3/include/bits/stl_iterator_base_types.h
+++ b/libstdc++-v3/include/bits/stl_iterator_base_types.h
@@ -243,16 +243,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus >= 201103L
   template<typename _Iter>
-    using __iterator_category_t
+    using __iter_category_t
       = typename iterator_traits<_Iter>::iterator_category;
 
   template<typename _InIter>
     using _RequireInputIter =
-      __enable_if_t<is_convertible<__iterator_category_t<_InIter>,
+      __enable_if_t<is_convertible<__iter_category_t<_InIter>,
 				   input_iterator_tag>::value>;
 
   template<typename _It,
-	   typename _Cat = __iterator_category_t<_It>>
+	   typename _Cat = __iter_category_t<_It>>
     struct __is_random_access_iter
       : is_base_of<random_access_iterator_tag, _Cat>
     {