[gcc r17-569] libstdc++: Include range_access.h from <valarray>

[Tomasz Kaminski]

https://gcc.gnu.org/g:83f056802116d09136d2f32d1accfe5a53a85a74

commit r17-569-g83f056802116d09136d2f32d1accfe5a53a85a74
Author: Tomasz Kamiński <tkaminsk@redhat.com>
Date:   Thu May 14 14:47:03 2026 +0200

    libstdc++: Include range_access.h from <valarray>
    
    This implements <valarray> related parts of section 4.8. of P3016R6.
    This is treated as DR against C++11 (to expose array begin/end), to follow
    similar changes to other semi-containers that were accepted as LWG issues
    and treated as DR: <optional> (LWG4131), <stacktrace> (LWG3625).
    
    libstdc++-v3/ChangeLog:
    
            * include/std/valarray [__cplusplus >= 201103L]: Include
            <bits/ranges_access.h>.
            * testsuite/26_numerics/valarray/range_access2.cc: Remove
            <iterator> include, and add test for std::size.
    
    Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
    Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>

Diff:
---
 libstdc++-v3/include/std/valarray                          |  1 +
 .../testsuite/26_numerics/valarray/range_access2.cc        | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/valarray b/libstdc++-v3/include/std/valarray
index 63784fb5974a..abb158d22c35 100644
--- a/libstdc++-v3/include/std/valarray
+++ b/libstdc++-v3/include/std/valarray
@@ -43,6 +43,7 @@
 #include <debug/debug.h>
 #if __cplusplus >= 201103L
 #include <initializer_list>
+#include <bits/range_access.h>
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
diff --git a/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc b/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc
index 8a4f2b659e5a..44ea7fc4b601 100644
--- a/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc
@@ -19,7 +19,6 @@
 
 // C++11 26.6.10 valarray range access: [valarray.range]
 
-#include <iterator>
 #include <valarray>
 
 // PR libstdc++/67374
@@ -46,8 +45,21 @@ test02()
   (void) std::cend(cva);
 }
 
+// P3016R6 4.8
+void
+test03()
+{
+#if __cplusplus >= 201703L
+  std::valarray<double> va;
+  (void) std::size(va);
+  const auto& cva = va;
+  (void) std::size(cva);
+#endif
+}
+
 int main()
 {
   test01();
   test02();
+  test03();
 }