[libcxx-commits] [libcxx] [libc++][C++26] P2562R1: `constexpr` Stable Sorting (PR #110320)

[A. Jiang via libcxx-commits]

================
@@ -80,66 +77,149 @@ test_sort_()
     }
 }
 
-void
-test_larger_sorts(int N, int M)
-{
-    assert(N != 0);
-    assert(M != 0);
-    // create array length N filled with M different numbers
-    int* array = new int[N];
-    int x = 0;
-    for (int i = 0; i < N; ++i)
-    {
-        array[i] = x;
-        if (++x == M)
-            x = 0;
+template <int N, int M>
+TEST_CONSTEXPR_CXX26 std::array<int, N> init_saw_tooth_pattern() {
+  std::array<int, N> array;
+  for (int i = 0, x = 0; i < N; ++i) {
+    array[i] = x;
+    if (++x == M)
+      x = 0;
+  }
+  return array;
+}
+
+template <int N, int M>
+TEST_CONSTEXPR_CXX26 std::array<int, N> sort_saw_tooth_pattern() {
+  std::array<int, N> array = init_saw_tooth_pattern<N, M>();
+  std::stable_sort(array.begin(), array.end());
+  return array;
+}
+
+template <int N, int M>
+TEST_CONSTEXPR_CXX26 std::array<int, N> sort_already_sorted() {
+  std::array<int, N> array = sort_saw_tooth_pattern<N, M>();
+  std::stable_sort(array.begin(), array.end());
+  return array;
+}
+
+template <int N, int M>
+std::array<int, N> sort_reversely_sorted() {
+  std::array<int, N> array = sort_saw_tooth_pattern<N, M>();
+  std::reverse(array.begin(), array.end());
+  std::stable_sort(array.begin(), array.end());
+  return array;
+}
+
+template <int N, int M>
+TEST_CONSTEXPR_CXX26 std::array<int, N> sort_swapped_sorted_ranges() {
+  std::array<int, N> array = sort_saw_tooth_pattern<N, M>();
+  std::swap_ranges(array.begin(), array.begin() + N / 2, array.begin() + N / 2);
+  std::stable_sort(array.begin(), array.end());
+  return array;
+}
+
+template <int N, int M>
+std::array<int, N> sort_reversely_swapped_sorted_ranges() {
+  std::array<int, N> array = sort_saw_tooth_pattern<N, M>();
+  std::reverse(array.begin(), array.end());
+  std::swap_ranges(array.begin(), array.begin() + N / 2, array.begin() + N / 2);
+  std::stable_sort(array.begin(), array.end());
+  return array;
+}
+
+#if _LIBCPP_STD_VER >= 26
----------------
frederick-vs-ja wrote:

In the test files we should use `TEST_STD_VER`.

```suggestion
#if TEST_STD_VER >= 26
```

Ditto below.

https://github.com/llvm/llvm-project/pull/110320