[libc++] constexpr flat_set (llvm#140360)

Fixes llvm#128675

Author: huixie90

libcxx/include/__flat_set/flat_set.h

@@ -38,7 +38,8 @@ struct __flat_set_utils {
   // When an exception is thrown during the emplacement, the function will clear the set if the container does not
   // have strong exception safety guarantee on emplacement.
   template <class _Set, class _Iter, class _KeyArg>
-  _LIBCPP_HIDE_FROM_ABI static auto __emplace_exact_pos(_Set& __set, _Iter&& __iter, _KeyArg&& __key) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static auto
+  __emplace_exact_pos(_Set& __set, _Iter&& __iter, _KeyArg&& __key) {
     using _KeyContainer = typename decay_t<_Set>::container_type;
     auto __on_failure   = std::__make_exception_guard([&]() noexcept {
       if constexpr (!__container_traits<_KeyContainer>::__emplacement_has_strong_exception_safety_guarantee) {
@@ -51,12 +52,13 @@ struct __flat_set_utils {
   }
 
   template <class _Set, class _InputIterator>
-  _LIBCPP_HIDE_FROM_ABI static void __append(_Set& __set, _InputIterator __first, _InputIterator __last) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static void
+  __append(_Set& __set, _InputIterator __first, _InputIterator __last) {
     __set.__keys_.insert(__set.__keys_.end(), std::move(__first), std::move(__last));
   }
 
   template <class _Set, class _Range>
-  _LIBCPP_HIDE_FROM_ABI static void __append(_Set& __set, _Range&& __rng) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static void __append(_Set& __set, _Range&& __rng) {
     if constexpr (requires { __set.__keys_.insert_range(__set.__keys_.end(), std::forward<_Range>(__rng)); }) {
       // C++23 Sequence Container should have insert_range member function
       // Note that not all Sequence Containers provide append_range.

libcxx/include/__flat_set/utils.h

@@ -1319,6 +1319,9 @@ module std [system] {
     export std.flat_map.sorted_unique
     export std.flat_map.sorted_equivalent
     export *
+    export std.algorithm.ranges_sort
+    export std.ranges.zip_view
+    export std.tuple
   }
 
   module format {

libcxx/include/module.modulemap.in

@@ -21,7 +21,7 @@
 #include "../flat_helpers.h"
 #include "test_macros.h"
 
-bool test() {
+constexpr bool test() {
   using M = std::flat_set<TrackCopyMove>;
   {
     M m;
@@ -43,6 +43,9 @@ bool test() {
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/libcxx/containers/container.adaptors/flat.set/insert.temporary.pass.cpp

@@ -24,23 +24,33 @@
 #include <vector>
 
 #include "../flat_helpers.h"
+#include "test_iterators.h"
 #include "test_macros.h"
 
-void test() {
+constexpr bool test() {
   NotQuiteSequenceContainer<int> v;
   std::flat_set s(v);
-  std::istringstream ints("0 1 1 0");
-  auto r = std::ranges::subrange(std::istream_iterator<int>(ints), std::istream_iterator<int>()) |
-           std::views::transform([](int i) { return i * i; });
+
+  int ar[]   = {0, 1, 1, 0};
+  using Iter = cpp20_input_iterator<const int*>;
+  using Sent = sentinel_wrapper<Iter>;
+  using R    = std::ranges::subrange<Iter, Sent>;
+  auto r     = R(Iter(ar), Sent(Iter(ar + 4)));
+
   static_assert(
       ![](auto& t) { return requires { t.insert_range(t.end(), r); }; }(v),
       "This test is to test the case where the underlying container does not provide insert_range");
   s.insert_range(r);
   assert(std::ranges::equal(s, std::vector<int>{0, 1}));
+
+  return true;
 }
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/libcxx/containers/container.adaptors/flat.set/insert_range.pass.cpp

@@ -24,7 +24,7 @@
 #include "min_allocator.h"
 
 template <class KeyContainer>
-void test_one() {
+constexpr void test_one() {
   using Key = typename KeyContainer::value_type;
   using M   = std::flat_set<Key, std::less<int>, KeyContainer>;
   M m;
@@ -38,15 +38,23 @@ void test_one() {
   assert(m.empty());
 }
 
-void test() {
+constexpr bool test() {
   test_one<std::vector<int>>();
-  test_one<std::deque<int>>();
+#ifndef __cpp_lib_constexpr_deque
+  if (!TEST_IS_CONSTANT_EVALUATED)
+#endif
+    test_one<std::deque<int>>();
   test_one<MinSequenceContainer<int>>();
   test_one<std::vector<int, min_allocator<int>>>();
+
+  return true;
 }
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.capacity/empty.pass.cpp

@@ -24,7 +24,7 @@
 #include "test_allocator.h"
 #include "test_macros.h"
 
-void test() {
+constexpr bool test() {
   {
     using A1 = limited_allocator<int, 10>;
     using C  = std::flat_set<int, std::less<int>, std::vector<int, A1>>;
@@ -59,10 +59,15 @@ void test() {
     assert(c.max_size() <= max_dist);
     assert(c.max_size() <= alloc_max_size(std::allocator<char>()));
   }
+
+  return true;
 }
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.capacity/max_size.pass.cpp

@@ -16,14 +16,15 @@
 #include <deque>
 #include <flat_set>
 #include <functional>
+#include <type_traits>
 #include <vector>
 
 #include "MinSequenceContainer.h"
 #include "test_macros.h"
 #include "min_allocator.h"
 
 template <class KeyContainer>
-void test_one() {
+constexpr void test_one() {
   using M = std::flat_set<int, std::less<int>, KeyContainer>;
   using S = typename M::size_type;
   {
@@ -46,7 +47,7 @@ void test_one() {
   }
   {
     M m;
-    S s = 1000000;
+    S s = TEST_IS_CONSTANT_EVALUATED ? 100 : 1000000;
     for (auto i = 0u; i < s; ++i) {
       m.emplace(i);
     }
@@ -56,15 +57,23 @@ void test_one() {
   }
 }
 
-void test() {
+constexpr bool test() {
   test_one<std::vector<int>>();
-  test_one<std::deque<int>>();
+#ifndef __cpp_lib_constexpr_deque
+  if (!TEST_IS_CONSTANT_EVALUATED)
+#endif
+    test_one<std::deque<int>>();
   test_one<MinSequenceContainer<int>>();
   test_one<std::vector<int, min_allocator<int>>>();
+
+  return true;
 }
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.capacity/size.pass.cpp

@@ -14,24 +14,27 @@
 //   explicit flat_set(const Allocator& a);
 
 #include <cassert>
+#include <deque>
 #include <flat_set>
 #include <functional>
 #include <vector>
 
+#include "MinSequenceContainer.h"
 #include "test_macros.h"
 #include "test_allocator.h"
 #include "../../../test_compare.h"
 
-void test() {
+template <template <class...> class KeyContainer>
+constexpr void test() {
   {
     // The constructors in this subclause shall not participate in overload
     // resolution unless uses_allocator_v<container_type, Alloc> is true.
 
     using C  = test_less<int>;
     using A1 = test_allocator<int>;
     using A2 = other_allocator<int>;
-    using V1 = std::vector<int, A1>;
-    using V2 = std::vector<int, A2>;
+    using V1 = KeyContainer<int, A1>;
+    using V2 = KeyContainer<int, A2>;
     using M1 = std::flat_set<int, C, V1>;
     using M2 = std::flat_set<int, C, V2>;
     static_assert(std::is_constructible_v<M1, const A1&>);
@@ -41,14 +44,14 @@ void test() {
   }
   {
     // explicit
-    using M = std::flat_set<int, std::less<int>, std::vector<int, test_allocator<int>>>;
+    using M = std::flat_set<int, std::less<int>, KeyContainer<int, test_allocator<int>>>;
 
     static_assert(std::is_constructible_v<M, test_allocator<int>>);
     static_assert(!std::is_convertible_v<test_allocator<int>, M>);
   }
   {
     using A = test_allocator<short>;
-    using M = std::flat_set<int, std::less<int>, std::vector<int, test_allocator<int>>>;
+    using M = std::flat_set<int, std::less<int>, KeyContainer<int, test_allocator<int>>>;
     M m(A(0, 5));
     assert(m.empty());
     assert(m.begin() == m.end());
@@ -57,8 +60,21 @@ void test() {
   }
 }
 
+constexpr bool test() {
+  test<std::vector>();
+#ifndef __cpp_lib_constexpr_deque
+  if (!TEST_IS_CONSTANT_EVALUATED)
+#endif
+    test<std::deque>();
+
+  return true;
+}
+
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.cons/alloc.pass.cpp

@@ -24,7 +24,7 @@
 #include "min_allocator.h"
 
 template <class KeyContainer>
-void test_one() {
+constexpr void test_one() {
   using Key = typename KeyContainer::value_type;
   using M   = std::flat_set<Key, std::less<Key>, KeyContainer>;
   {
@@ -45,17 +45,25 @@ void test_one() {
   }
 }
 
-void test() {
+constexpr bool test() {
   test_one<std::vector<int>>();
   test_one<std::vector<int>>();
-  test_one<std::deque<int>>();
+#ifndef __cpp_lib_constexpr_deque
+  if (!TEST_IS_CONSTANT_EVALUATED)
+#endif
+    test_one<std::deque<int>>();
   test_one<MinSequenceContainer<int>>();
   test_one<std::vector<int, min_allocator<int>>>();
   test_one<std::vector<int, min_allocator<int>>>();
+
+  return true;
 }
 
 int main(int, char**) {
   test();
+#if TEST_STD_VER >= 26
+  static_assert(test());
+#endif
 
   return 0;
 }