[libc++] [test] Add ranges_robust_against_copying_*.pass.cpp

[philnik]

Summary

This tests the same QoI issue as the existing STL Classic test,
but for the Ranges algorithms. Also, do the same thing for all
the algorithms that take projections.

I found a few missing algorithms and added them to the existing test, too. std::find_first_of currently fails; I should look at why that is (and in particular, what is it doing weird that makes it inconsistent with the entire rest of libc++?).

[philnik]

LGTM % nits.

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_comparators.pass.cpp

10–11

Shouldn't there also be // UNSUPPORTED: libcpp-no-concepts?

229

I'd like // (void) a bit more.

[• Quuxplusone]

Add libcpp-no-concepts. I'm surprised that there are platforms with libcpp-no-concepts yet without libcpp-has-no-incomplete-ranges! But OK.

[• Quuxplusone]

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_comparators.pass.cpp

229

For a permanent, informative comment, I'd 100% agree (but "don't comment out code").
These comments, though, are meant to be uncommented as we implement stuff, and be kinda ugly until then. Also, for consistency with the existing tests' commented-out stuff (e.g. in niebloid.compile.pass.cpp as well). So I'm leaving as-is. Let's make the question moot by implementing all these algorithms! ;)

[philnik]

Commandeering, since Arthur can't work on it currently.

[philnik]

• Fix CI; enable more tests

[ldionne]

LGTM with comments

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_comparators.pass.cpp

9

Both added tests could use a short comment explaining what they're testing. It's not difficult to figure out by reading the code, but it's always nice to have a comment in prose explaining exactly what this does -- it helps save time.

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_comparators.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, c++17
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// <algorithm>
+
+// this test checks that the comparators in the ranges algorithms aren't copied/moved
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+
+#include "test_macros.h"
+
+struct Less {
+    int *copies_;
+    constexpr explicit Less(int *copies) : copies_(copies) {}
+    constexpr Less(const Less& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr Less& operator=(const Less&) = default;
+    constexpr bool operator()(void*, void*) const { return false; }
+};
+
+struct Equal {
+    int *copies_;
+    constexpr explicit Equal(int *copies) : copies_(copies) {}
+    constexpr Equal(const Equal& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr Equal& operator=(const Equal&) = default;
+    constexpr bool operator()(void*, void*) const { return true; }
+};
+
+struct UnaryVoid {
+    int *copies_;
+    constexpr explicit UnaryVoid(int *copies) : copies_(copies) {}
+    constexpr UnaryVoid(const UnaryVoid& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr UnaryVoid& operator=(const UnaryVoid&) = default;
+    constexpr void operator()(void*) const {}
+};
+
+struct UnaryTrue {
+    int *copies_;
+    constexpr explicit UnaryTrue(int *copies) : copies_(copies) {}
+    constexpr UnaryTrue(const UnaryTrue& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr UnaryTrue& operator=(const UnaryTrue&) = default;
+    constexpr bool operator()(void*) const { return true; }
+};
+
+struct NullaryValue {
+    int *copies_;
+    constexpr explicit NullaryValue(int *copies) : copies_(copies) {}
+    constexpr NullaryValue(const NullaryValue& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr NullaryValue& operator=(const NullaryValue&) = default;
+    constexpr std::nullptr_t operator()() const { return nullptr; }
+};
+
+struct UnaryTransform {
+    int *copies_;
+    constexpr explicit UnaryTransform(int *copies) : copies_(copies) {}
+    constexpr UnaryTransform(const UnaryTransform& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr UnaryTransform& operator=(const UnaryTransform&) = default;
+    constexpr std::nullptr_t operator()(void*) const { return nullptr; }
+};
+
+struct BinaryTransform {
+    int *copies_;
+    constexpr explicit BinaryTransform(int *copies) : copies_(copies) {}
+    constexpr BinaryTransform(const BinaryTransform& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr BinaryTransform& operator=(const BinaryTransform&) = default;
+    constexpr std::nullptr_t operator()(void*, void*) const { return nullptr; }
+};
+
+constexpr bool all_the_algorithms()
+{
+    void *a[10] = {};
+    void *b[10] = {};
+    //void *half[5] = {};
+    void **first = a;
+    //void **mid = a+5;
+    void **last = a+10;
+    void **first2 = b;
+    //void **mid2 = b+5;
+    void **last2 = b+10;
+    //void *value = nullptr;
+    //int count = 1;
+
+    int copies = 0;
+    //(void)std::ranges::adjacent_find(first, last, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::adjacent_find(a, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::all_of(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::all_of(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::any_of(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::any_of(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::binary_search(first, last, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::binary_search(a, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::clamp(value, value, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::count_if(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::count_if(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::copy_if(first, last, first2, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::copy_if(a, first2, UnaryTrue(&copies)); assert(copies == 0);
+#if TEST_STD_VER > 20
+    //(void)std::ranges::ends_with(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+#endif
+    //(void)std::ranges::equal(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal(a, b, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal_range(first, last, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal_range(a, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_end(first, last, first2, mid2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_end(a, b, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_first_of(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_first_of(a, b, Equal(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if(a, UnaryTrue(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if_not(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if_not(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::for_each(first, last, UnaryVoid(&copies)); assert(copies == 1); copies = 0;
+    //(void)std::ranges::for_each(a, UnaryVoid(&copies)); assert(copies == 1); copies = 0;
+    //(void)std::ranges::for_each_n(first, count, UnaryVoid(&copies)); assert(copies == 0);
+    //(void)std::ranges::generate(first, last, NullaryValue(&copies)); assert(copies == 0);
+    //(void)std::ranges::generate(a, NullaryValue(&copies)); assert(copies == 0);
+    //(void)std::ranges::generate_n(first, count, NullaryValue(&copies)); assert(copies == 0);
+    //(void)std::ranges::includes(first, last, first2, last2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::includes(a, b, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap_until(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap_until(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_partitioned(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_partitioned(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_permutation(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_permutation(a, b, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted_until(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted_until(a, Less(&copies)); assert(copies == 0);
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::inplace_merge(first, mid, last, Less(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::inplace_merge(a, mid, Less(&copies)); assert(copies == 0); }
+    //(void)std::ranges::lexicographical_compare(first, last, first2, last2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::lexicographical_compare(a, b, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::lower_bound(first, last, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::lower_bound(a, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::make_heap(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::make_heap(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::max(value, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::max({ value, value }, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::max(a, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::max_element(first, last, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::max_element(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::merge(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::merge(half, half, b, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::min(value, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::min({ value, value }, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::min(a, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::min_element(first, last, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::min_element(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax(value, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax({ value, value }, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax_element(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax_element(a, Less(&copies)); assert(copies == 0);
+    (void)std::ranges::mismatch(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+    (void)std::ranges::mismatch(a, b, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::next_permutation(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::next_permutation(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::none_of(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::none_of(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::nth_element(first, mid, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::nth_element(a, mid, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort(first, mid, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort(a, mid, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort_copy(first, last, first2, mid2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort_copy(a, b, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_copy(first, last, first2, last2, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_copy(a, first2, last2, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_point(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_point(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::pop_heap(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::pop_heap(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::prev_permutation(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::prev_permutation(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::push_heap(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::push_heap(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy_if(first, last, first2, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy_if(a, first2, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_if(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_if(a, UnaryTrue(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_copy_if(first, last, first2, UnaryTrue(&copies), value); assert(copies == 0);
+    //(void)std::ranges::replace_copy_if(a, first2, UnaryTrue(&copies), value); assert(copies == 0);
+    //(void)std::ranges::replace_if(first, last, UnaryTrue(&copies), value); assert(copies == 0);
+    //(void)std::ranges::replace_if(a, UnaryTrue(&copies), value); assert(copies == 0);
+    //(void)std::ranges::search(first, last, first2, mid2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::search(a, b, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::search_n(first, last, count, value, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::search_n(a, count, value, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_difference(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_difference(a, b, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_intersection(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_intersection(a, b, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_symmetric_difference(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_symmetric_difference(a, b, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_union(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_union(a, b, first2, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort(a, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort_heap(first, last, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort_heap(a, Less(&copies)); assert(copies == 0);
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(first, last, UnaryTrue(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(a, UnaryTrue(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_sort(first, last, Less(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_sort(a, Less(&copies)); assert(copies == 0); }
+#if TEST_STD_VER > 20
+    //(void)std::ranges::starts_with(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
+#endif
+    //(void)std::ranges::transform(first, last, first2, UnaryTransform(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(a, first2, UnaryTransform(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(first, mid, mid, last, first2, BinaryTransform(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(a, b, first2, BinaryTransform(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique(first, last, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique(a, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique_copy(first, last, first2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique_copy(a, first2, Equal(&copies)); assert(copies == 0);
+    //(void)std::ranges::upper_bound(first, last, value, Less(&copies)); assert(copies == 0);
+    //(void)std::ranges::upper_bound(a, value, Less(&copies)); assert(copies == 0);
+
+    return true;
+}
+
+int main(int, char**)
+{
+    all_the_algorithms();
+    static_assert(all_the_algorithms());
+
+    return 0;
+}

libcxx/test/libcxx/algorithms/ranges_robust_against_copying_projections.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, c++17
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// <algorithm>
+
+// this test checks that the projections in the ranges algorithms aren't copied/moved
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+
+#include "test_macros.h"
+
+struct T {};
+
+struct Proj {
+    int *copies_;
+    constexpr explicit Proj(int *copies) : copies_(copies) {}
+    constexpr Proj(const Proj& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr Proj& operator=(const Proj&) = default;
+    constexpr void *operator()(T) const { return nullptr; }
+};
+
+struct Less {
+    constexpr bool operator()(void*, void*) const { return false; }
+};
+
+struct Equal {
+    constexpr bool operator()(void*, void*) const { return true; }
+};
+
+struct UnaryVoid {
+    constexpr void operator()(void*) const {}
+};
+
+struct UnaryTrue {
+    constexpr bool operator()(void*) const { return true; }
+};
+
+struct NullaryValue {
+    constexpr std::nullptr_t operator()() const { return nullptr; }
+};
+
+struct UnaryTransform {
+    constexpr T operator()(void*) const { return T(); }
+};
+
+struct BinaryTransform {
+    constexpr T operator()(void*, void*) const { return T(); }
+};
+
+constexpr bool all_the_algorithms()
+{
+    T a[10] = {};
+    T b[10] = {};
+    //T half[5] = {};
+    T *first = a;
+    //T *mid = a+5;
+    T *last = a+10;
+    T *first2 = b;
+    //T *mid2 = b+5;
+    T *last2 = b+10;
+    void *value = nullptr;
+    //int count = 1;
+
+    int copies = 0;
+    //(void)std::ranges::adjacent_find(first, last, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::adjacent_find(a, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::all_of(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::all_of(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::any_of(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::any_of(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::binary_search(first, last, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::binary_search(a, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::clamp(T(), T(), T(), Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::count(first, last, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::count(a, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::count_if(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::count_if(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::copy_if(first, last, first2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::copy_if(a, first2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+#if TEST_STD_VER > 20
+    //(void)std::ranges::ends_with(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+#endif
+    //(void)std::ranges::equal(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal_range(first, last, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::equal_range(a, value, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find(first, last, value, Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find(a, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_end(first, last, first2, mid2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_end(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_first_of(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::find_first_of(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if_not(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::find_if_not(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::for_each(first, last, UnaryVoid(), Proj(&copies)); assert(copies == 1); copies = 0;
+    //(void)std::ranges::for_each(a, UnaryVoid(), Proj(&copies)); assert(copies == 1); copies = 0;
+    //(void)std::ranges::for_each_n(first, count, UnaryVoid(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::includes(first, last, first2, last2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::includes(a, b, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap_until(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_heap_until(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_partitioned(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_partitioned(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_permutation(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_permutation(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted_until(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::is_sorted_until(a, Less(), Proj(&copies)); assert(copies == 0);
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::inplace_merge(first, mid, last, Less(), Proj(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::inplace_merge(a, mid, Less(), Proj(&copies)); assert(copies == 0); }
+    //(void)std::ranges::lexicographical_compare(first, last, first2, last2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::lexicographical_compare(a, b, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::lower_bound(first, last, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::lower_bound(a, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::make_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::make_heap(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::max(T(), T(), Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::max({ T(), T() }, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::max(a, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::max_element(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::max_element(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::merge(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::merge(half, half, b, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::min(T(), T(), Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::min({ T(), T() }, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::min(a, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::min_element(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::min_element(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax(T(), T(), Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax({ T(), T() }, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax_element(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::minmax_element(a, Less(), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::mismatch(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    (void)std::ranges::mismatch(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::next_permutation(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::next_permutation(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::none_of(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::none_of(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::nth_element(first, mid, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::nth_element(a, mid, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort(first, mid, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort(a, mid, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort_copy(first, last, first2, mid2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partial_sort_copy(a, b, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_copy(first, last, first2, last2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_copy(a, first2, last2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_point(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::partition_point(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::pop_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::pop_heap(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::prev_permutation(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::prev_permutation(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::push_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::push_heap(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy(first, last, first2, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy(a, first2, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy_if(first, last, first2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_copy_if(a, first2, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove(first, last, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove(a, value, Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_if(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::remove_if(a, UnaryTrue(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_copy(first, last, first2, value, T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_copy(a, first2, value, T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_copy_if(first, last, first2, UnaryTrue(), T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_copy_if(a, first2, UnaryTrue(), T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace(first, last, value, T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace(a, value, T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_if(first, last, UnaryTrue(), T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::replace_if(a, UnaryTrue(), T(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::search(first, last, first2, mid2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::search(a, b, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::search_n(first, last, count, value, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::search_n(a, count, value, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_difference(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_difference(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_intersection(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_intersection(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_symmetric_difference(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_symmetric_difference(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_union(first, mid, mid, last, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::set_union(a, b, first2, Less(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort(a, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort_heap(first, last, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::sort_heap(a, Less(), Proj(&copies)); assert(copies == 0);
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(first, last, UnaryTrue(), Proj(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_partition(a, UnaryTrue(), Proj(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_sort(first, last, Less(), Proj(&copies)); assert(copies == 0); }
+    //if (!std::is_constant_evaluated()) { (void)std::ranges::stable_sort(a, Less(), Proj(&copies)); assert(copies == 0); }
+#if TEST_STD_VER > 20
+    //(void)std::ranges::starts_with(first, last, first2, last2, Equal(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+#endif
+    //(void)std::ranges::transform(first, last, first2, UnaryTransform(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(a, first2, UnaryTransform(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(first, mid, mid, last, first2, BinaryTransform(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::transform(a, b, first2, BinaryTransform(), Proj(&copies), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique(first, last, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique(a, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique_copy(first, last, first2, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::unique_copy(a, first2, Equal(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::upper_bound(first, last, value, Less(), Proj(&copies)); assert(copies == 0);
+    //(void)std::ranges::upper_bound(a, value, Less(), Proj(&copies)); assert(copies == 0);
+
+    return true;
+}
+
+int main(int, char**)
+{
+    all_the_algorithms();
+    static_assert(all_the_algorithms());
+
+    return 0;
+}

libcxx/test/libcxx/algorithms/robust_against_copying_comparators.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
 //
 //===----------------------------------------------------------------------===//
 
 // <algorithm>
 
 #include <algorithm>
 #include <cassert>
+#include <compare>
 #include <cstddef>
 
 #include "test_macros.h"
 
 struct Less {
     int *copies_;
     TEST_CONSTEXPR explicit Less(int *copies) : copies_(copies) {}
     TEST_CONSTEXPR_CXX14 Less(const Less& rhs) : copies_(rhs.copies_) { *copies_ += 1; }

 struct BinaryTransform {
     int *copies_;
     TEST_CONSTEXPR explicit BinaryTransform(int *copies) : copies_(copies) {}
     TEST_CONSTEXPR_CXX14 BinaryTransform(const BinaryTransform& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
     TEST_CONSTEXPR_CXX14 BinaryTransform& operator=(const BinaryTransform&) = default;
     TEST_CONSTEXPR std::nullptr_t operator()(void*, void*) const { return nullptr; }
 };
 
+#if TEST_STD_VER > 17
+struct ThreeWay {
+    int *copies_;
+    constexpr explicit ThreeWay(int *copies) : copies_(copies) {}
+    constexpr ThreeWay(const ThreeWay& rhs) : copies_(rhs.copies_) { *copies_ += 1; }
+    constexpr ThreeWay& operator=(const ThreeWay&) = default;
+    constexpr std::strong_ordering operator()(void*, void*) const { return std::strong_ordering::equal; }
+};
+#endif
+
 TEST_CONSTEXPR_CXX20 bool all_the_algorithms()
 {
     void *a[10] = {};
     void *b[10] = {};
     void **first = a;
     void **mid = a+5;
     void **last = a+10;
     void **first2 = b;
     void **mid2 = b+5;
     void **last2 = b+10;
     void *value = nullptr;
     int count = 1;
 
     int copies = 0;
     (void)std::adjacent_find(first, last, Equal(&copies)); assert(copies == 0);
 #if TEST_STD_VER >= 11
     (void)std::all_of(first, last, UnaryTrue(&copies)); assert(copies == 0);
     (void)std::any_of(first, last, UnaryTrue(&copies)); assert(copies == 0);
 #endif
     (void)std::binary_search(first, last, value, Less(&copies)); assert(copies == 0);
 #if TEST_STD_VER > 17
     (void)std::clamp(value, value, value, Less(&copies)); assert(copies == 0);
 #endif
     (void)std::count_if(first, last, UnaryTrue(&copies)); assert(copies == 0);
+    (void)std::copy_if(first, last, first2, UnaryTrue(&copies)); assert(copies == 0);
     (void)std::equal(first, last, first2, Equal(&copies)); assert(copies == 0);
 #if TEST_STD_VER > 11
     (void)std::equal(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
 #endif
     (void)std::equal_range(first, last, value, Less(&copies)); assert(copies == 0);
     (void)std::find_end(first, last, first2, mid2, Equal(&copies)); assert(copies == 0);
+    //(void)std::find_first_of(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
     (void)std::find_if(first, last, UnaryTrue(&copies)); assert(copies == 0);
     (void)std::find_if_not(first, last, UnaryTrue(&copies)); assert(copies == 0);
     (void)std::for_each(first, last, UnaryVoid(&copies)); assert(copies == 1); copies = 0;
 #if TEST_STD_VER > 14
     (void)std::for_each_n(first, count, UnaryVoid(&copies)); assert(copies == 0);
 #endif
     (void)std::generate(first, last, NullaryValue(&copies)); assert(copies == 0);
     (void)std::generate_n(first, count, NullaryValue(&copies)); assert(copies == 0);
     (void)std::includes(first, last, first2, last2, Less(&copies)); assert(copies == 0);
     (void)std::is_heap(first, last, Less(&copies)); assert(copies == 0);
     (void)std::is_heap_until(first, last, Less(&copies)); assert(copies == 0);
     (void)std::is_partitioned(first, last, UnaryTrue(&copies)); assert(copies == 0);
     (void)std::is_permutation(first, last, first2, Equal(&copies)); assert(copies == 0);
 #if TEST_STD_VER > 11
     (void)std::is_permutation(first, last, first2, last2, Equal(&copies)); assert(copies == 0);
 #endif
     (void)std::is_sorted(first, last, Less(&copies)); assert(copies == 0);
     (void)std::is_sorted_until(first, last, Less(&copies)); assert(copies == 0);
     if (!TEST_IS_CONSTANT_EVALUATED) { (void)std::inplace_merge(first, mid, last, Less(&copies)); assert(copies == 0); }
     (void)std::lexicographical_compare(first, last, first2, last2, Less(&copies)); assert(copies == 0);
-    // TODO: lexicographical_compare_three_way
+#if TEST_STD_VER > 17
+    //(void)std::lexicographical_compare_three_way(first, last, first2, last2, ThreeWay(&copies)); assert(copies == 0);
+#endif
     (void)std::lower_bound(first, last, value, Less(&copies)); assert(copies == 0);
     (void)std::make_heap(first, last, Less(&copies)); assert(copies == 0);
     (void)std::max(value, value, Less(&copies)); assert(copies == 0);
 #if TEST_STD_VER >= 11
     (void)std::max({ value, value }, Less(&copies)); assert(copies == 0);
 #endif
     (void)std::max_element(first, last, Less(&copies)); assert(copies == 0);
     (void)std::merge(first, mid, mid, last, first2, Less(&copies)); assert(copies == 0);