1 files changed, 43 insertions, 0 deletions
diff --git a/libstdc++-v3/testsuite/24_iterators/common_iterator/100823.cc b/libstdc++-v3/testsuite/24_iterators/common_iterator/100823.cc
new file mode 100644
index 00000000000..4f2b23de8cc
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/common_iterator/100823.cc
@@ -0,0 +1,43 @@
+// { dg-options "-std=gnu++20 -D_GLIBCXX_ASSERTIONS" }
+// { dg-do run { target c++20 } }
+#include <iterator>
+#include <testsuite_iterators.h>
+#include <testsuite_hooks.h>
+
+void
+test_valueless_assignment()
+{
+  int x[1] { };
+  __gnu_test::test_forward_range<int> r(x);
+  using Iter = decltype(r.begin());
+  using Sent = decltype(r.end());
+
+  std::common_iterator<Iter, Sent> i;
+  const std::common_iterator<Iter, Sent> j(r.begin());
+  try
+  {
+    struct Bomb
+    {
+      bool operator==(Iter) const { return true; }
+      operator Sent() const { throw 1; }
+    };
+    std::common_iterator<Iter, Bomb> b{Bomb{}};
+    i = b; // Throws, leaving i valueless-by-exception.
+    VERIFY(false);
+  }
+  catch (int)
+  {
+    std::common_iterator<Iter, Sent> k(i);
+
+    // PR libstdc++/100823
+    k = i; // Valid even though both operands are valueless.
+
+    i = j; // No longer valueless.
+  }
+  VERIFY( i == j );
+}
+
+int main()
+{
+  test_valueless_assignment();
+}