1 files changed, 22 insertions, 0 deletions
diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill_n.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill_n.pass.cpp
index 2d6e24a03e0b..25db892548a6 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill_n.pass.cpp
@@ -16,6 +16,7 @@
 #include <algorithm>
 #include <array>
 #include <cassert>
+#include <deque>
 #include <ranges>
 #include <string>
 #include <vector>
@@ -101,6 +102,13 @@ constexpr bool test_vector_bool(std::size_t N) {
 }
 #endif
 
+/*TEST_CONSTEXPR_CXX26*/ void test_deque() { // TODO: Mark as TEST_CONSTEXPR_CXX26 once std::deque is constexpr
+  std::deque<int> in(20);
+  std::deque<int> expected(in.size(), 42);
+  std::ranges::fill_n(std::ranges::begin(in), std::ranges::size(in), 42);
+  assert(in == expected);
+}
+
 constexpr bool test() {
   test_iterators<cpp17_output_iterator<int*>, sentinel_wrapper<cpp17_output_iterator<int*>>>();
   test_iterators<cpp20_output_iterator<int*>, sentinel_wrapper<cpp20_output_iterator<int*>>>();
@@ -175,6 +183,20 @@ constexpr bool test() {
   }
 #endif
 
+  if (!TEST_IS_CONSTANT_EVALUATED) // TODO: Use TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED when std::deque is made constexpr
+    test_deque();
+
+#if TEST_STD_VER >= 20
+  {
+    std::vector<std::vector<int>> v{{1, 2}, {1, 2, 3}, {}, {3, 4, 5}, {6}, {7, 8, 9, 6}, {0, 1, 2, 3, 0, 1, 2}};
+    auto jv = std::ranges::join_view(v);
+    std::ranges::fill_n(std::ranges::begin(jv), std::ranges::distance(jv), 42);
+    for (const auto& vec : v)
+      for (auto n : vec)
+        assert(n == 42);
+  }
+#endif
+
   return true;
 }