[PATCH 1/4] libstdc++: Add already-accepted <ranges> testcase [PR106320]

[Patrick Palka <ppalka@redhat.com>]

Although PR106320 only affected the 10 and 11 branches, and the testcase
from there was already correctly accepted on trunk and the 12 branch, we
should also add the testcase to 12/trunk for inter-branch consistency.

Tested on x86_64-pc-linux-gnu, does this look OK for trunk/12?

	PR libstdc++/106320

libstdc++-v3/ChangeLog:

	* testsuite/std/ranges/adaptors/join.cc (test13): New test.
---
 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();
 }
-- 
2.37.3.542.gdd3f6c4cae