From f8284b7e458192284ec9ca0eea606d93edbaab85 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Thu, 8 Jun 2023 15:02:44 -0600
Subject: [PATCH] Inherit iterator traits from the underlying class.

---
 include/deal.II/hp/collection.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/deal.II/hp/collection.h b/include/deal.II/hp/collection.h
index 6e8e89f2da..acc5860f6e 100644
--- a/include/deal.II/hp/collection.h
+++ b/include/deal.II/hp/collection.h
@@ -21,6 +21,7 @@
 #include <deal.II/base/memory_consumption.h>
 #include <deal.II/base/subscriptor.h>
 
+#include <iterator>
 #include <memory>
 #include <vector>
 
@@ -306,11 +307,9 @@ namespace std
    */
   template <class T>
   struct iterator_traits<dealii::hp::CollectionIterator<T>>
-  {
-    using iterator_category = random_access_iterator_tag;
-    using value_type        = T;
-    using difference_type   = std::ptrdiff_t;
-  };
+    : public iterator_traits<
+        typename std::vector<std::shared_ptr<const T>>::iterator>
+  {};
 } // namespace std
 
 #endif
-- 
2.39.5