[PATCH] libstdc++: LWG 3397 basic_istream_view::iterator should not provide iterator_category

[Patrick Palka]

libstdc++-v3/ChangeLog:

        LWG 3397 basic_istream_view::iterator should not provide
        iterator_category
        * include/std/ranges (basic_istream_view:_Iterator::iterator_category):
        Rename to ...
        (basic_istream_view:_Iterator::iterator_concept): ... this.
        * testsuite/std/ranges/istream_view.cc: Augment test.
---
 libstdc++-v3/include/std/ranges                  |  2 +-
 .../testsuite/std/ranges/istream_view.cc         | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 442d1d08098..a7f4da957ef 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -971,7 +971,7 @@ namespace views
       struct _Iterator
       {
       public:
-       using iterator_category = input_iterator_tag;
+       using iterator_concept = input_iterator_tag;
        using difference_type = ptrdiff_t;
        using value_type = _Val;
 
diff --git a/libstdc++-v3/testsuite/std/ranges/istream_view.cc 
b/libstdc++-v3/testsuite/std/ranges/istream_view.cc
index 1729459bce3..f74e05e347a 100644
--- a/libstdc++-v3/testsuite/std/ranges/istream_view.cc
+++ b/libstdc++-v3/testsuite/std/ranges/istream_view.cc
@@ -68,10 +68,26 @@ test03()
   VERIFY( ranges::equal(v, (int[]){0,1,2,3,4}) );
 }
 
+template<typename T>
+concept has_iterator_category = requires { typename T::iterator_category; };
+
+void
+test04()
+{
+  std::istringstream s("12345");
+  auto v = ranges::istream_view<char>(s);
+  // LWG 3397
+  using It = ranges::iterator_t<decltype(v)>;
+  static_assert(!has_iterator_category<It>);
+  static_assert(std::input_iterator<It>);
+  static_assert(!std::forward_iterator<It>);
+}
+
 int
 main()
 {
   test01();
   test02();
   test03();
+  test04();
 }
-- 
2.25.1.291.ge68e29171c