[libc++][PSTL] Add a test to make sure that customization points work properly

[ldionne]

LGTM with green CI, thanks for adding this!

FWIW I think it's reasonable to disable this test when modules are enabled, this is inherently non-modular.

libcxx/include/__algorithm/pstl_backend.h

64–70

Those are missing the _Backend tag.

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Try to fix CI

[philnik]

Rebased

libcxx/include/__algorithm/pstl_backend.h

 
 // TODO: Complete this list
 
 The following functions are optional but can be provided. If provided, they are used by the corresponding
 algorithms, otherwise they are implemented in terms of other algorithms. If none of the optional algorithms are
 implemented, all the algorithms will eventually forward to the basis algorithms listed above:
 
   template <class _ExecutionPolicy, class _Iterator, class _Size, class _Func>
-  void __pstl_for_each_n(_Backend, _ExecutionPolicy&&, _Iterator __first, _Size __n, _Func __f);
+  void __pstl_for_each_n(_Backend, _Iterator __first, _Size __n, _Func __f);
 
   template <class _ExecutionPolicy, class _Iterator, class _Predicate>
   bool __pstl_any_of(_Backend, _Iterator __first, _iterator __last, _Predicate __pred);
 
   template <class _ExecutionPolicy, class _Iterator, class _Predicate>
   bool __pstl_all_of(_Backend, _Iterator __first, _iterator __last, _Predicate __pred);
 
   template <class _ExecutionPolicy, class _Iterator, class _Predicate>
   bool __pstl_none_of(_Backend, _Iterator __first, _iterator __last, _Predicate __pred);
 
   template <class _ExecutionPolicy, class _Iterator, class _Tp>
-  void __pstl_fill(_Iterator __first, _Iterator __last, const _Tp& __value);
+  _Iterator __pstl_find(_Backend, _Iterator __first, _Iterator __last, const _Tp& __value);
+
+  template <class _ExecutionPolicy, class _Iterator, class _Predicate>
+  _Iterator __pstl_find_if_not(_Backend, _Iterator __first, _Iterator __last, _Predicate __pred);
+
+  template <class _ExecutionPolicy, class _Iterator, class _Tp>
+  void __pstl_fill(_Backend, _Iterator __first, _Iterator __last, const _Tp& __value);
 
   template <class _ExecutionPolicy, class _Iterator, class _SizeT, class _Tp>
-  void __pstl_fill_n(_Iterator __first, _SizeT __n, const _Tp& __value);
+  void __pstl_fill_n(_Backend, _Iterator __first, _SizeT __n, const _Tp& __value);
 
 // TODO: Complete this list
 
 */
 
 template <class _ExecutionPolicy>
 struct __select_backend;
 

libcxx/test/libcxx/algorithms/pstl.robust_against_customization_points_not_working.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// 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
+// UNSUPPORTED: modules-build
+
+// Make sure that the customization points get called properly when overloaded
+
+#include <__config>
+#include <cassert>
+
+struct TestPolicy {};
+struct TestBackend {};
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+bool pstl_any_of_called = false;
+
+template <class, class ForwardIterator, class Pred>
+bool __pstl_any_of(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_any_of_called);
+  pstl_any_of_called = true;
+  return true;
+}
+
+bool pstl_all_of_called = false;
+
+template <class, class ForwardIterator, class Pred>
+bool __pstl_all_of(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_all_of_called);
+  pstl_all_of_called = true;
+  return true;
+}
+
+bool pstl_none_of_called = false;
+
+template <class, class ForwardIterator, class Pred>
+bool __pstl_none_of(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_none_of_called);
+  pstl_none_of_called = true;
+  return true;
+}
+
+bool pstl_find_called = false;
+
+template <class, class ForwardIterator, class Pred>
+ForwardIterator __pstl_find(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_find_called);
+  pstl_find_called = true;
+  return {};
+}
+
+bool pstl_find_if_called = false;
+
+template <class, class ForwardIterator, class Pred>
+ForwardIterator __pstl_find_if(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_find_if_called);
+  pstl_find_if_called = true;
+  return {};
+}
+
+bool pstl_find_if_not_called = false;
+
+template <class, class ForwardIterator, class Pred>
+ForwardIterator __pstl_find_if_not(TestBackend, ForwardIterator, ForwardIterator, Pred) {
+  assert(!pstl_find_if_not_called);
+  pstl_find_if_not_called = true;
+  return {};
+}
+
+bool pstl_for_each_called = false;
+
+template <class, class ForwardIterator, class Size, class Func>
+void __pstl_for_each(TestBackend, ForwardIterator, Size, Func) {
+  assert(!pstl_for_each_called);
+  pstl_for_each_called = true;
+}
+
+bool pstl_for_each_n_called = false;
+
+template <class, class ForwardIterator, class Size, class Func>
+void __pstl_for_each_n(TestBackend, ForwardIterator, Size, Func) {
+  assert(!pstl_for_each_n_called);
+  pstl_for_each_n_called = true;
+}
+
+bool pstl_fill_called = false;
+
+template <class, class ForwardIterator, class Size, class Func>
+void __pstl_fill(TestBackend, ForwardIterator, Size, Func) {
+  assert(!pstl_fill_called);
+  pstl_fill_called = true;
+}
+
+bool pstl_fill_n_called = false;
+
+template <class, class ForwardIterator, class Size, class Func>
+void __pstl_fill_n(TestBackend, ForwardIterator, Size, Func) {
+  assert(!pstl_fill_n_called);
+  pstl_fill_n_called = true;
+}
+
+bool pstl_unary_transform_called = false;
+
+template <class, class ForwardIterator, class ForwardOutIterator, class UnaryOperation>
+ForwardOutIterator __pstl_transform(TestBackend, ForwardIterator, ForwardIterator, ForwardOutIterator, UnaryOperation) {
+  assert(!pstl_unary_transform_called);
+  pstl_unary_transform_called = true;
+  return {};
+}
+
+bool pstl_binary_transform_called = false;
+
+template <class, class ForwardIterator1, class ForwardIterator2, class ForwardOutIterator, class BinaryOperation>
+ForwardOutIterator __pstl_transform(
+    TestBackend, ForwardIterator1, ForwardIterator1, ForwardIterator2, ForwardOutIterator, BinaryOperation) {
+  assert(!pstl_binary_transform_called);
+  pstl_binary_transform_called = true;
+  return {};
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#include <algorithm>
+#include <cassert>
+#include <iterator>
+
+template <>
+inline constexpr bool std::is_execution_policy_v<TestPolicy> = true;
+
+template <>
+struct std::__select_backend<TestPolicy> {
+  using type = TestBackend;
+};
+
+int main(int, char**) {
+  int a[]   = {1, 2};
+  auto pred = [](auto&&...) { return true; };
+
+  (void)std::any_of(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_any_of_called);
+  (void)std::all_of(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_all_of_called);
+  (void)std::none_of(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_none_of_called);
+  (void)std::fill(TestPolicy{}, std::begin(a), std::end(a), 0);
+  assert(std::pstl_fill_called);
+  (void)std::fill_n(TestPolicy{}, std::begin(a), std::size(a), 0);
+  assert(std::pstl_fill_n_called);
+  (void)std::find(TestPolicy{}, std::begin(a), std::end(a), 0);
+  assert(std::pstl_find_called);
+  (void)std::find_if(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_find_if_called);
+  (void)std::find_if_not(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_find_if_not_called);
+  (void)std::for_each(TestPolicy{}, std::begin(a), std::end(a), pred);
+  assert(std::pstl_for_each_called);
+  (void)std::for_each_n(TestPolicy{}, std::begin(a), std::size(a), pred);
+  assert(std::pstl_for_each_n_called);
+  (void)std::transform(TestPolicy{}, std::begin(a), std::end(a), std::begin(a), pred);
+  assert(std::pstl_unary_transform_called);
+  (void)std::transform(TestPolicy{}, std::begin(a), std::end(a), std::begin(a), std::begin(a), pred);
+  assert(std::pstl_unary_transform_called);
+
+  return 0;
+}