[libc++][test] Refactor tests for rotate and rotate_copy (llvm#126458)

This PR refactors the tests and fix some problems:  
- Refactor similar tests using `types::for_each` to remove redundant code;
- Explicitly include the missing header `type_algorithms.h` instead of relying
  on a transitive include;
- Fix the incorrect constexpr declaration in `rotate.pass.cpp`, where
  the `test()` function is incorrectly defined as `TEST_CONSTEXPR_CXX17`,
  which is wrong since `std::rotate()` becomes constexpr only since C++20.

Author: winner245

libcxx/test/std/algorithms/alg.modifying.operations/alg.rotate/pstl.rotate_copy.pass.cpp

@@ -27,6 +27,7 @@
 #include "test_macros.h"
 #include "test_execution_policies.h"
 #include "test_iterators.h"
+#include "type_algorithms.h"
 
 template <class Iter>
 struct Test {

libcxx/test/std/algorithms/alg.modifying.operations/alg.rotate/ranges.rotate_copy.pass.cpp

@@ -26,9 +26,11 @@
 
 #include "almost_satisfies_types.h"
 #include "test_iterators.h"
+#include "type_algorithms.h"
 
 template <class Iter, class Out = int*, class Sent = sentinel_wrapper<Iter>>
-concept HasRotateCopyIt = requires(Iter first, Sent last, Out out) { std::ranges::rotate_copy(first, first, last, out); };
+concept HasRotateCopyIt =
+    requires(Iter first, Sent last, Out out) { std::ranges::rotate_copy(first, first, last, out); };
 
 template <class Range, class Out = int*>
 concept HasRotateCopyR = requires(Range range, Out out) { std::ranges::rotate_copy(range, nullptr, out); };
@@ -54,11 +56,8 @@ template <class Iter, class OutIter, class Sent, int N>
 constexpr void test(std::array<int, N> value, std::size_t middle, std::array<int, N> expected) {
   {
     std::array<int, N> out;
-    std::same_as<std::ranges::in_out_result<Iter, OutIter>> decltype(auto) ret =
-        std::ranges::rotate_copy(Iter(value.data()),
-                                 Iter(value.data() + middle),
-                                 Sent(Iter(value.data() + value.size())),
-                                 OutIter(out.data()));
+    std::same_as<std::ranges::in_out_result<Iter, OutIter>> decltype(auto) ret = std::ranges::rotate_copy(
+        Iter(value.data()), Iter(value.data() + middle), Sent(Iter(value.data() + value.size())), OutIter(out.data()));
     assert(base(ret.in) == value.data() + value.size());
     assert(base(ret.out) == out.data() + out.size());
     assert(out == expected);
@@ -101,41 +100,33 @@ constexpr void test_iterators() {
   test<Iter, OutIter, Sent, 7>({1, 2, 3, 4, 5, 6, 7}, 7, {1, 2, 3, 4, 5, 6, 7});
 }
 
-template <class Iter, class Sent = Iter>
-constexpr void test_out_iterators() {
-  test_iterators<Iter, cpp20_output_iterator<int*>, Sent>();
-  test_iterators<Iter, forward_iterator<int*>, Sent>();
-  test_iterators<Iter, bidirectional_iterator<int*>, Sent>();
-  test_iterators<Iter, random_access_iterator<int*>, Sent>();
-  test_iterators<Iter, contiguous_iterator<int*>, Sent>();
-  test_iterators<Iter, int*, Sent>();
-}
-
 constexpr bool test() {
-  test_out_iterators<forward_iterator<int*>>();
-  test_out_iterators<bidirectional_iterator<int*>>();
-  test_out_iterators<random_access_iterator<int*>>();
-  test_out_iterators<contiguous_iterator<int*>>();
-  test_out_iterators<int*>();
-  test_out_iterators<const int*>();
+  types::for_each(types::forward_iterator_list<const int*>(), []<class Iter>() {
+    types::for_each(
+        types::concatenate_t<types::forward_iterator_list<int*>, types::type_list<cpp20_output_iterator<int*> > >(),
+        []<class OutIter>() { test_iterators<Iter, OutIter, Iter>(); });
+  });
 
   {
     struct AssignmentCounter {
       int* counter;
 
       constexpr AssignmentCounter(int* counter_) : counter(counter_) {}
-      constexpr AssignmentCounter& operator=(const AssignmentCounter&) { ++*counter; return *this; }
+      constexpr AssignmentCounter& operator=(const AssignmentCounter&) {
+        ++*counter;
+        return *this;
+      }
     };
 
     {
-      int c = 0;
+      int c                 = 0;
       AssignmentCounter a[] = {&c, &c, &c, &c};
       AssignmentCounter b[] = {&c, &c, &c, &c};
       std::ranges::rotate_copy(a, a + 2, a + 4, b);
       assert(c == 4);
     }
     {
-      int c = 0;
+      int c                 = 0;
       AssignmentCounter a[] = {&c, &c, &c, &c};
       AssignmentCounter b[] = {&c, &c, &c, &c};
       std::ranges::rotate_copy(a, a + 2, b);

libcxx/test/std/algorithms/alg.modifying.operations/alg.rotate/ranges_rotate.pass.cpp

@@ -24,15 +24,15 @@
 
 #include "almost_satisfies_types.h"
 #include "test_iterators.h"
+#include "type_algorithms.h"
 
 // Test constraints of the (iterator, sentinel) overload.
 // ======================================================
 
 template <class Iter = int*, class Sent = int*>
-concept HasRotateIter =
-    requires(Iter&& iter, Sent&& sent) {
-      std::ranges::rotate(std::forward<Iter>(iter), std::forward<Iter>(iter), std::forward<Sent>(sent));
-    };
+concept HasRotateIter = requires(Iter&& iter, Sent&& sent) {
+  std::ranges::rotate(std::forward<Iter>(iter), std::forward<Iter>(iter), std::forward<Sent>(sent));
+};
 
 static_assert(HasRotateIter<int*, int*>);
 
@@ -48,10 +48,9 @@ static_assert(!HasRotateIter<int*, SentinelForNotWeaklyEqualityComparableWith>);
 // =========================================
 
 template <class Range>
-concept HasRotateRange =
-    requires(Range&& range, std::ranges::iterator_t<Range> iter) {
-      std::ranges::rotate(std::forward<Range>(range), iter);
-    };
+concept HasRotateRange = requires(Range&& range, std::ranges::iterator_t<Range> iter) {
+  std::ranges::rotate(std::forward<Range>(range), iter);
+};
 
 template <class T>
 using R = UncheckedRange<T>;
@@ -73,10 +72,10 @@ constexpr void test_one(const std::array<int, N> input, std::size_t mid_index, s
   assert(mid_index <= N);
 
   { // (iterator, sentinel) overload.
-    auto in = input;
+    auto in    = input;
     auto begin = Iter(in.data());
-    auto mid = Iter(in.data() + mid_index);
-    auto end = Sent(Iter(in.data() + in.size()));
+    auto mid   = Iter(in.data() + mid_index);
+    auto end   = Sent(Iter(in.data() + in.size()));
 
     std::same_as<std::ranges::subrange<Iter>> decltype(auto) result = std::ranges::rotate(begin, mid, end);
     assert(base(result.begin()) == in.data() + in.size() - mid_index);
@@ -85,10 +84,10 @@ constexpr void test_one(const std::array<int, N> input, std::size_t mid_index, s
   }
 
   { // (range) overload.
-    auto in = input;
+    auto in    = input;
     auto begin = Iter(in.data());
-    auto mid = Iter(in.data() + mid_index);
-    auto end = Sent(Iter(in.data() + in.size()));
+    auto mid   = Iter(in.data() + mid_index);
+    auto end   = Sent(Iter(in.data() + in.size()));
     auto range = std::ranges::subrange(std::move(begin), std::move(end));
 
     std::same_as<std::ranges::subrange<Iter>> decltype(auto) result = std::ranges::rotate(range, mid);
@@ -132,32 +131,21 @@ constexpr void test_iter_sent() {
   test_one<Iter, Sent, 7>({1, 2, 3, 4, 5, 6, 7}, 7, {1, 2, 3, 4, 5, 6, 7});
 }
 
-template <class Iter>
-constexpr void test_iter() {
-  test_iter_sent<Iter, Iter>();
-  test_iter_sent<Iter, sentinel_wrapper<Iter>>();
-}
-
-constexpr void test_iterators() {
-  test_iter<forward_iterator<int*>>();
-  test_iter<bidirectional_iterator<int*>>();
-  test_iter<random_access_iterator<int*>>();
-  test_iter<contiguous_iterator<int*>>();
-  test_iter<int*>();
-}
-
 constexpr bool test() {
-  test_iterators();
+  types::for_each(types::forward_iterator_list<int*>(), []<class Iter>() {
+    test_iter_sent<Iter, Iter>();
+    test_iter_sent<Iter, sentinel_wrapper<Iter>>();
+  });
 
   { // Complexity: at most `last - first` swaps.
     const std::array input = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
-    auto expected = static_cast<int>(input.size());
+    auto expected          = static_cast<int>(input.size());
 
     {
-      auto in = input;
-      int swaps = 0;
+      auto in    = input;
+      int swaps  = 0;
       auto begin = adl::Iterator::TrackSwaps(in.data(), swaps);
-      auto end = adl::Iterator::TrackSwaps(in.data() + in.size(), swaps);
+      auto end   = adl::Iterator::TrackSwaps(in.data() + in.size(), swaps);
 
       for (std::size_t mid = 0; mid != input.size(); ++mid) {
         std::ranges::rotate(begin, begin + mid, end);
@@ -166,10 +154,10 @@ constexpr bool test() {
     }
 
     {
-      auto in = input;
-      int swaps = 0;
+      auto in    = input;
+      int swaps  = 0;
       auto begin = adl::Iterator::TrackSwaps(in.data(), swaps);
-      auto end = adl::Iterator::TrackSwaps(in.data() + in.size(), swaps);
+      auto end   = adl::Iterator::TrackSwaps(in.data() + in.size(), swaps);
       auto range = std::ranges::subrange(begin, end);
 
       for (std::size_t mid = 0; mid != input.size(); ++mid) {