[gcc(refs/vendors/ibm/heads/perf)] libstdc++: make common_iterator<I, S> require copyable<I> (LWG 3385)

[Jiu Fu Guo]

https://gcc.gnu.org/g:1b425f3ac516f7250e9f7eac7cd4fe0908ccfa4e

commit 1b425f3ac516f7250e9f7eac7cd4fe0908ccfa4e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Feb 19 21:56:29 2020 +0000

    libstdc++: make common_iterator<I, S> require copyable<I> (LWG 3385)
    
            * include/bits/stl_iterator.h (common_iterator): Add copyable<I>
            requirement (LWG 3385).
            * testsuite/24_iterators/headers/iterator/synopsis_c++20.cc: Adjust
            expected declaration.

Diff:
---
 libstdc++-v3/ChangeLog                                               | 5 +++++
 libstdc++-v3/include/bits/stl_iterator.h                             | 2 +-
 .../testsuite/24_iterators/headers/iterator/synopsis_c++20.cc        | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index ef91b80ef45..7f3f8876957 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-19  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/stl_iterator.h (common_iterator): Add copyable<I>
+	requirement (LWG 3385).
+	* testsuite/24_iterators/headers/iterator/synopsis_c++20.cc: Adjust
+	expected declaration.
+
 	* include/std/ranges (take_while_view, drop_view, drop_while_view)
 	(elements_view:_Iterator): Initialize data members (LWG 3364).
 
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index fc9d442b475..372df223113 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -1426,7 +1426,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /// An iterator/sentinel adaptor for representing a non-common range.
   template<input_or_output_iterator _It, sentinel_for<_It> _Sent>
-    requires (!same_as<_It, _Sent>)
+    requires (!same_as<_It, _Sent>) && copyable<_It>
   class common_iterator
   {
     template<typename _Tp, typename _Up>
diff --git a/libstdc++-v3/testsuite/24_iterators/headers/iterator/synopsis_c++20.cc b/libstdc++-v3/testsuite/24_iterators/headers/iterator/synopsis_c++20.cc
index 4d8eca31d38..fbe116be2fd 100644
--- a/libstdc++-v3/testsuite/24_iterators/headers/iterator/synopsis_c++20.cc
+++ b/libstdc++-v3/testsuite/24_iterators/headers/iterator/synopsis_c++20.cc
@@ -56,7 +56,7 @@ namespace std
   template<semiregular S> class move_sentinel;
 
   template<input_or_output_iterator I, sentinel_for<I> S>
-    requires (!same_as<I, S>)
+    requires (!same_as<I, S>) && copyable<I>
     class common_iterator;
 
   template<class I, class S>