[libc++] Add ranges::in_fun_result

Add `ranges::in_fun_result`

Reviewed By: Quuxplusone, #libc, var-const

Spies: CaseyCarter, var-const, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D116974

Author: philnik777

libcxx/include/CMakeLists.txt

@@ -26,6 +26,7 @@ set(files
   __algorithm/generate.h
   __algorithm/generate_n.h
   __algorithm/half_positive.h
+  __algorithm/in_fun_result.h
   __algorithm/in_in_out_result.h
   __algorithm/in_in_result.h
   __algorithm/in_out_out_result.h

libcxx/include/__algorithm/in_fun_result.h

@@ -0,0 +1,49 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_IN_FUN_RESULT_H
+#define _LIBCPP___ALGORITHM_IN_FUN_RESULT_H
+
+#include <__concepts/convertible_to.h>
+#include <__config>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_HAS_NO_CONCEPTS
+
+namespace ranges {
+template <class _Ip, class _Fp>
+struct in_fun_result {
+  [[no_unique_address]] _Ip in;
+  [[no_unique_address]] _Fp fun;
+
+  template <class _I2, class _F2>
+    requires convertible_to<const _Ip&, _I2> && convertible_to<const _Fp&, _F2>
+  _LIBCPP_HIDE_FROM_ABI constexpr operator in_fun_result<_I2, _F2>() const & {
+    return {in, fun};
+  }
+
+  template <class _I2, class _F2>
+    requires convertible_to<_Ip, _I2> && convertible_to<_Fp, _F2>
+  _LIBCPP_HIDE_FROM_ABI constexpr operator in_fun_result<_I2, _F2>() && {
+    return {std::move(in), std::move(fun)};
+  }
+};
+} // namespace ranges
+
+#endif // _LIBCPP_HAS_NO_RANGES
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ALGORITHM_IN_FUN_RESULT_H

libcxx/include/algorithm

@@ -19,6 +19,9 @@ namespace std
 {
 
 namespace ranges {
+  template <class I, class F>
+    struct in_fun_result; // since C++20
+
   template <class I1, class I2>
     struct in_in_result;     // since C++20
 
@@ -27,6 +30,9 @@ namespace ranges {
 
   template <class I, class O1, class O2>
     struct in_out_out_result; // since C++20
+
+  template<class I, class O>
+    struct in_out_result; // since C++20
 }
 
 template <class InputIterator, class Predicate>
@@ -661,13 +667,6 @@ template <class BidirectionalIterator>
 template <class BidirectionalIterator, class Compare>
     constexpr bool     // constexpr in C++20
     prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
-
-namespace ranges {
-// [algorithms.results], algorithm result types
-template<class InputIterator, class OutputIterator>
-    struct in_out_result;
-}
-
 }  // std
 
 */
@@ -712,6 +711,7 @@ template<class InputIterator, class OutputIterator>
 #include <__algorithm/generate.h>
 #include <__algorithm/generate_n.h>
 #include <__algorithm/half_positive.h>
+#include <__algorithm/in_fun_result.h>
 #include <__algorithm/in_in_out_result.h>
 #include <__algorithm/in_in_result.h>
 #include <__algorithm/in_out_out_result.h>

libcxx/include/module.modulemap

@@ -247,6 +247,7 @@ module std [system] {
       module generate                 { private header "__algorithm/generate.h" }
       module generate_n               { private header "__algorithm/generate_n.h" }
       module half_positive            { private header "__algorithm/half_positive.h" }
+      module in_fun_result            { private header "__algorithm/in_fun_result.h" }
       module in_in_out_result         { private header "__algorithm/in_in_out_result.h" }
       module in_in_result             { private header "__algorithm/in_in_result.h" }
       module in_out_out_result        { private header "__algorithm/in_out_out_result.h" }

libcxx/test/libcxx/diagnostics/detail.headers/algorithm/in_fun_result.module.verify.cpp

@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-build
+
+// WARNING: This test was generated by 'generate_private_header_tests.py'
+// and should not be edited manually.
+
+// expected-error@*:* {{use of private header from outside its module: '__algorithm/in_fun_result.h'}}
+#include <__algorithm/in_fun_result.h>

libcxx/test/std/algorithms/algorithms.results/in_fun_result.pass.cpp

@@ -0,0 +1,101 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// template <class I1, class I2>
+// struct in_fun_result;
+
+#include <algorithm>
+#include <cassert>
+#include <type_traits>
+#include <utility>
+
+#include "MoveOnly.h"
+
+struct A {
+  explicit A(int);
+};
+// no implicit conversion
+static_assert(!std::is_constructible_v<std::ranges::in_fun_result<A, A>, std::ranges::in_fun_result<int, int>>);
+
+struct B {
+  B(int);
+};
+// implicit conversion
+static_assert(std::is_constructible_v<std::ranges::in_fun_result<B, B>, std::ranges::in_fun_result<int, int>>);
+static_assert(std::is_constructible_v<std::ranges::in_fun_result<B, B>, std::ranges::in_fun_result<int, int>&>);
+static_assert(std::is_constructible_v<std::ranges::in_fun_result<B, B>, const std::ranges::in_fun_result<int, int>>);
+static_assert(std::is_constructible_v<std::ranges::in_fun_result<B, B>, const std::ranges::in_fun_result<int, int>&>);
+
+struct C {
+  C(int&);
+};
+// has to be convertible via const&
+static_assert(!std::is_constructible_v<std::ranges::in_fun_result<C, C>, std::ranges::in_fun_result<int, int>&>);
+
+static_assert(std::is_convertible_v<std::ranges::in_fun_result<int, int>&, std::ranges::in_fun_result<long, long>>);
+static_assert(std::is_convertible_v<const std::ranges::in_fun_result<int, int>&, std::ranges::in_fun_result<long, long>>);
+static_assert(std::is_convertible_v<std::ranges::in_fun_result<int, int>&&, std::ranges::in_fun_result<long, long>>);
+static_assert(std::is_convertible_v<const std::ranges::in_fun_result<int, int>&&, std::ranges::in_fun_result<long, long>>);
+
+// should be move constructible
+static_assert(std::is_move_constructible_v<std::ranges::in_fun_result<MoveOnly, int>>);
+static_assert(std::is_move_constructible_v<std::ranges::in_fun_result<int, MoveOnly>>);
+
+// should not copy constructible with move-only type
+static_assert(!std::is_copy_constructible_v<std::ranges::in_fun_result<MoveOnly, int>>);
+static_assert(!std::is_copy_constructible_v<std::ranges::in_fun_result<int, MoveOnly>>);
+
+struct NotConvertible {};
+// conversions should not work if there is no conversion
+static_assert(!std::is_convertible_v<std::ranges::in_fun_result<NotConvertible, int>,
+                                     std::ranges::in_fun_result<int, int>>);
+static_assert(!std::is_convertible_v<std::ranges::in_fun_result<int, NotConvertible>,
+                                     std::ranges::in_fun_result<int, int>>);
+
+template <class T>
+struct ConvertibleFrom {
+  constexpr ConvertibleFrom(T c) : content{c} {}
+  T content;
+};
+
+constexpr bool test() {
+  {
+    std::ranges::in_fun_result<int, double> res{10, 0.};
+    assert(res.in == 10);
+    assert(res.fun == 0.);
+    std::ranges::in_fun_result<ConvertibleFrom<int>, ConvertibleFrom<double>> res2 = res;
+    assert(res2.in.content == 10);
+    assert(res2.fun.content == 0.);
+  }
+  {
+    std::ranges::in_fun_result<MoveOnly, int> res{MoveOnly{}, 2};
+    assert(res.in.get() == 1);
+    assert(res.fun == 2);
+    auto res2 = static_cast<std::ranges::in_fun_result<MoveOnly, int>>(std::move(res));
+    assert(res.in.get() == 0);
+    assert(res2.in.get() == 1);
+    assert(res2.fun == 2);
+  }
+  {
+    auto [in, fun] = std::ranges::in_fun_result<int, int>{1, 2};
+    assert(in == 1);
+    assert(fun == 2);
+  }
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}

libcxx/test/std/algorithms/algorithms.results/no_unique_address.compile.pass.cpp

@@ -44,3 +44,7 @@ static_assert(sizeof(std::ranges::in_out_out_result<Empty, char, Empty>) == 2);
 static_assert(sizeof(std::ranges::in_out_out_result<Empty, Empty, char>) == 2);
 static_assert(sizeof(std::ranges::in_out_out_result<int, Empty, Empty2>) == sizeof(int));
 static_assert(sizeof(std::ranges::in_out_out_result<Empty, Empty, Empty>) == 3);
+
+static_assert(sizeof(std::ranges::in_fun_result<Empty, int>) == sizeof(int));
+static_assert(sizeof(std::ranges::in_fun_result<int, Empty>) == sizeof(int));
+static_assert(sizeof(std::ranges::in_fun_result<Empty, Empty>) == 2);