[gcc r13-425] libstdc++: Improve doxygen docs for std::pointer_traits

[gcc r13-425] libstdc++: Improve doxygen docs for std::pointer_traits

[Jonathan Wakely]

https://gcc.gnu.org/g:757146fb1c82b49e78ee82c882677814f25c2429

commit r13-425-g757146fb1c82b49e78ee82c882677814f25c2429
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed May 11 16:13:16 2022 +0100

    libstdc++: Improve doxygen docs for std::pointer_traits
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/ptr_traits.h: Add some doxygen comments.

Diff:
---
 libstdc++-v3/include/bits/ptr_traits.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libstdc++-v3/include/bits/ptr_traits.h b/libstdc++-v3/include/bits/ptr_traits.h
index 047efa5cf28..8360c3b6557 100644
--- a/libstdc++-v3/include/bits/ptr_traits.h
+++ b/libstdc++-v3/include/bits/ptr_traits.h
@@ -47,6 +47,8 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+  /// @cond undocumented
+
   class __undefined;
 
   // For a specialization `SomeTemplate<T, Types...>` the member `type` is T,
@@ -91,6 +93,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     using __ptr_traits_elem_t = typename __ptr_traits_elem<_Ptr>::type;
 #endif
 
+  /// @endcond
+
   // Define pointer_traits<P>::pointer_to.
   template<typename _Ptr, typename _Elt, bool = is_void<_Elt>::value>
     struct __ptr_traits_ptr_to
@@ -187,6 +191,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /**
    * @brief  Uniform interface to all pointer-like types
+   * @headerfile memory
    * @ingroup pointer_abstractions
    * @since C++11
   */
@@ -203,6 +208,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /**
    * @brief  Partial specialization for built-in pointers.
+   * @headerfile memory
    * @ingroup pointer_abstractions
    * @since C++11
   */