[gcc r12-8757] libstdc++: Add already-accepted <ranges> testcase [PR106320]

[Patrick Palka <ppalka@gcc.gnu.org>]

https://gcc.gnu.org/g:f323610375f4f87098f98b501ab01d033c930558

commit r12-8757-gf323610375f4f87098f98b501ab01d033c930558
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Sep 12 15:05:04 2022 -0400

    libstdc++: Add already-accepted <ranges> testcase [PR106320]
    
    Although PR106320 affected only the 10 and 11 branches, and the testcase
    from there is already correctly accepted on trunk and the 12 branch, we
    still should add the testcase to trunk/12 too for inter-branch consistency.
    
            PR libstdc++/106320
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/std/ranges/adaptors/join.cc (test13): New test.
    
    (cherry picked from commit db19cfdac8ede93172aecc58612171c239c993ad)

Diff:
---
 libstdc++-v3/testsuite/std/ranges/adaptors/join.cc | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
index 8986f718229..530ab6663b5 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
@@ -205,6 +205,18 @@ test12()
   }();
 }
 
+void
+test13()
+{
+  // PR libstdc++/106320
+  auto l = std::views::transform([](auto x) {
+    return x | std::views::transform([i=0](auto y) {
+      return y;
+    });
+  });
+  std::vector<std::vector<int>> v{{5, 6, 7}};
+  v | l | std::views::join;
+}
 int
 main()
 {
@@ -220,4 +232,5 @@ main()
   test10();
   test11();
   test12();
+  test13();
 }