[libcxx-commits] [libcxx] [libc++][ranges] LWG3692: `zip_view::iterator`'s `operator<=>` is overconstrained and changes of `zip_view` in P2165R4 (PR #112077)
A. Jiang via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Oct 11 20:59:22 PDT 2024
https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/112077
The changes are nearly pure simplifications, so I think it's OK to do them together in the same PR.
Actual test coverages were already added in commit ad41d1e26b12855fbb2b3104580a8d2b63bd5827 (https://reviews.llvm.org/D141216). Thanks to @CaseyCarter!
Fixes #104975. Towards #105200.
>From 33f3a61d667b8e30efef6e3229d1ebbf150f05b7 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Sat, 12 Oct 2024 11:56:06 +0800
Subject: [PATCH] [libc++][ranges] LWG3692: `zip_view::iterator`'s
`operator<=>` is overconstrained and changes of `zip_view` in P2165R4
The changes are nearly pure simplifications, so I think it's OK to do
them together in the same PR.
Actual test coverages were already added in
commit ad41d1e26b12855fbb2b3104580a8d2b63bd5827
(https://reviews.llvm.org/D141216). Thanks to @CaseyCarter!
---
libcxx/docs/Status/Cxx23Issues.csv | 2 +-
libcxx/docs/Status/Cxx23Papers.csv | 2 +-
libcxx/include/__ranges/zip_view.h | 52 +++----------------
.../range.adaptors/range.zip/cpo.pass.cpp | 4 --
.../range.zip/ctor.default.pass.cpp | 6 +--
.../range.zip/iterator/compare.pass.cpp | 16 +-----
.../range.zip/iterator/deref.pass.cpp | 8 ---
.../iterator/member_types.compile.pass.cpp | 14 +----
.../range.zip/iterator/subscript.pass.cpp | 8 ---
9 files changed, 13 insertions(+), 99 deletions(-)
diff --git a/libcxx/docs/Status/Cxx23Issues.csv b/libcxx/docs/Status/Cxx23Issues.csv
index 63e4176ecba1d7..cfa721230e5fb8 100644
--- a/libcxx/docs/Status/Cxx23Issues.csv
+++ b/libcxx/docs/Status/Cxx23Issues.csv
@@ -168,7 +168,7 @@
"`LWG3672 <https://wg21.link/LWG3672>`__","``common_iterator::operator->()`` should return by value","2022-07 (Virtual)","|Complete|","19.0",""
"`LWG3683 <https://wg21.link/LWG3683>`__","``operator==`` for ``polymorphic_allocator`` cannot deduce template argument in common cases","2022-07 (Virtual)","|Complete|","20.0",""
"`LWG3687 <https://wg21.link/LWG3687>`__","``expected<cv void, E>`` move constructor should move","2022-07 (Virtual)","|Complete|","16.0",""
-"`LWG3692 <https://wg21.link/LWG3692>`__","``zip_view::iterator``'s ``operator<=>`` is overconstrained","2022-07 (Virtual)","","",""
+"`LWG3692 <https://wg21.link/LWG3692>`__","``zip_view::iterator``'s ``operator<=>`` is overconstrained","2022-07 (Virtual)","|Complete|","20.0",""
"`LWG3701 <https://wg21.link/LWG3701>`__","Make ``formatter<remove_cvref_t<const charT[N]>, charT>`` requirement explicit","2022-07 (Virtual)","|Complete|","15.0",""
"`LWG3702 <https://wg21.link/LWG3702>`__","Should ``zip_transform_view::iterator`` remove ``operator<``","2022-07 (Virtual)","","",""
"`LWG3703 <https://wg21.link/LWG3703>`__","Missing requirements for ``expected<T, E>`` requires ``is_void<T>``","2022-07 (Virtual)","|Complete|","16.0",""
diff --git a/libcxx/docs/Status/Cxx23Papers.csv b/libcxx/docs/Status/Cxx23Papers.csv
index da7b5881877135..80636f22dacc76 100644
--- a/libcxx/docs/Status/Cxx23Papers.csv
+++ b/libcxx/docs/Status/Cxx23Papers.csv
@@ -60,7 +60,7 @@
"`P1642R11 <https://wg21.link/P1642R11>`__","Freestanding ``[utilities]``, ``[ranges]``, and ``[iterators]``","2022-07 (Virtual)","","",""
"`P1899R3 <https://wg21.link/P1899R3>`__","``stride_view``","2022-07 (Virtual)","","",""
"`P2093R14 <https://wg21.link/P2093R14>`__","Formatted output","2022-07 (Virtual)","|Complete|","18.0",""
-"`P2165R4 <https://wg21.link/P2165R4>`__","Compatibility between ``tuple``, ``pair`` and ``tuple-like`` objects","2022-07 (Virtual)","","",""
+"`P2165R4 <https://wg21.link/P2165R4>`__","Compatibility between ``tuple``, ``pair`` and ``tuple-like`` objects","2022-07 (Virtual)","|Partial|","","Only the part for ``zip_view`` is implemented`."
"`P2278R4 <https://wg21.link/P2278R4>`__","``cbegin`` should always return a constant iterator","2022-07 (Virtual)","","",""
"`P2286R8 <https://wg21.link/P2286R8>`__","Formatting Ranges","2022-07 (Virtual)","|Complete|","16.0",""
"`P2291R3 <https://wg21.link/P2291R3>`__","Add Constexpr Modifiers to Functions ``to_chars`` and ``from_chars`` for Integral Types in ``<charconv>`` Header","2022-07 (Virtual)","|Complete|","16.0",""
diff --git a/libcxx/include/__ranges/zip_view.h b/libcxx/include/__ranges/zip_view.h
index fe3c87a9306fe9..3ff49b8c1c6267 100644
--- a/libcxx/include/__ranges/zip_view.h
+++ b/libcxx/include/__ranges/zip_view.h
@@ -36,7 +36,6 @@
#include <__utility/forward.h>
#include <__utility/integer_sequence.h>
#include <__utility/move.h>
-#include <__utility/pair.h>
#include <tuple>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -58,21 +57,11 @@ concept __zip_is_common =
(!(bidirectional_range<_Ranges> && ...) && (common_range<_Ranges> && ...)) ||
((random_access_range<_Ranges> && ...) && (sized_range<_Ranges> && ...));
-template <typename _Tp, typename _Up>
-auto __tuple_or_pair_test() -> pair<_Tp, _Up>;
-
-template <typename... _Types>
- requires(sizeof...(_Types) != 2)
-auto __tuple_or_pair_test() -> tuple<_Types...>;
-
-template <class... _Types>
-using __tuple_or_pair = decltype(__tuple_or_pair_test<_Types...>());
-
template <class _Fun, class _Tuple>
_LIBCPP_HIDE_FROM_ABI constexpr auto __tuple_transform(_Fun&& __f, _Tuple&& __tuple) {
return std::apply(
[&]<class... _Types>(_Types&&... __elements) {
- return __tuple_or_pair<invoke_result_t<_Fun&, _Types>...>(
+ return tuple<invoke_result_t<_Fun&, _Types>...>(
std::invoke(__f, std::forward<_Types>(__elements))...);
},
std::forward<_Tuple>(__tuple));
@@ -88,7 +77,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr void __tuple_for_each(_Fun&& __f, _Tuple&& __tup
}
template <class _Fun, class _Tuple1, class _Tuple2, size_t... _Indices>
-_LIBCPP_HIDE_FROM_ABI constexpr __tuple_or_pair<
+_LIBCPP_HIDE_FROM_ABI constexpr tuple<
invoke_result_t<_Fun&,
typename tuple_element<_Indices, remove_cvref_t<_Tuple1>>::type,
typename tuple_element<_Indices, remove_cvref_t<_Tuple2>>::type>...>
@@ -250,10 +239,10 @@ template <input_range... _Views>
requires(view<_Views> && ...) && (sizeof...(_Views) > 0)
template <bool _Const>
class zip_view<_Views...>::__iterator : public __zip_view_iterator_category_base<_Const, _Views...> {
- __tuple_or_pair<iterator_t<__maybe_const<_Const, _Views>>...> __current_;
+ tuple<iterator_t<__maybe_const<_Const, _Views>>...> __current_;
_LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(
- __tuple_or_pair<iterator_t<__maybe_const<_Const, _Views>>...> __current)
+ tuple<iterator_t<__maybe_const<_Const, _Views>>...> __current)
: __current_(std::move(__current)) {}
template <bool>
@@ -266,7 +255,7 @@ class zip_view<_Views...>::__iterator : public __zip_view_iterator_category_base
public:
using iterator_concept = decltype(__get_zip_view_iterator_tag<_Const, _Views...>());
- using value_type = __tuple_or_pair<range_value_t<__maybe_const<_Const, _Views>>...>;
+ using value_type = tuple<range_value_t<__maybe_const<_Const, _Views>>...>;
using difference_type = common_type_t<range_difference_t<__maybe_const<_Const, _Views>>...>;
_LIBCPP_HIDE_FROM_ABI __iterator() = default;
@@ -340,33 +329,8 @@ class zip_view<_Views...>::__iterator : public __zip_view_iterator_category_base
}
}
- _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
- requires __zip_all_random_access<_Const, _Views...>
- {
- return __x.__current_ < __y.__current_;
- }
-
- _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
- requires __zip_all_random_access<_Const, _Views...>
- {
- return __y < __x;
- }
-
- _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
- requires __zip_all_random_access<_Const, _Views...>
- {
- return !(__y < __x);
- }
-
- _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
- requires __zip_all_random_access<_Const, _Views...>
- {
- return !(__x < __y);
- }
-
_LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
- requires __zip_all_random_access<_Const, _Views...> &&
- (three_way_comparable<iterator_t<__maybe_const<_Const, _Views>>> && ...)
+ requires __zip_all_random_access<_Const, _Views...>
{
return __x.__current_ <=> __y.__current_;
}
@@ -427,10 +391,10 @@ template <input_range... _Views>
requires(view<_Views> && ...) && (sizeof...(_Views) > 0)
template <bool _Const>
class zip_view<_Views...>::__sentinel {
- __tuple_or_pair<sentinel_t<__maybe_const<_Const, _Views>>...> __end_;
+ tuple<sentinel_t<__maybe_const<_Const, _Views>>...> __end_;
_LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(
- __tuple_or_pair<sentinel_t<__maybe_const<_Const, _Views>>...> __end)
+ tuple<sentinel_t<__maybe_const<_Const, _Views>>...> __end)
: __end_(__end) {}
friend class zip_view<_Views...>;
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/cpo.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/cpo.pass.cpp
index ea5953cefa0ff3..bdfd58ff8bbe78 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/cpo.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/cpo.pass.cpp
@@ -63,11 +63,7 @@ constexpr bool test() {
std::ranges::zip_view<std::ranges::zip_view<SizedRandomAccessView, SizedRandomAccessView>>> decltype(auto) v2 =
std::views::zip(v);
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<std::ranges::range_reference_t<decltype(v2)>, std::tuple<std::pair<int&, int&>>>);
-#else
static_assert(std::is_same_v<std::ranges::range_reference_t<decltype(v2)>, std::tuple<std::tuple<int&, int&>>>);
-#endif
}
return true;
}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/ctor.default.pass.cpp
index f53289621eabba..fdfcc02a8fb1c1 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/ctor.default.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/ctor.default.pass.cpp
@@ -49,12 +49,8 @@ constexpr bool test() {
using View = std::ranges::zip_view<DefaultConstructibleView, DefaultConstructibleView>;
View v = View(); // the default constructor is not explicit
assert(v.size() == 3);
- auto it = v.begin();
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- using Value = std::pair<const int&, const int&>;
-#else
+ auto it = v.begin();
using Value = std::tuple<const int&, const int&>;
-#endif
assert(*it++ == Value(buff[0], buff[0]));
assert(*it++ == Value(buff[1], buff[1]));
assert(*it == Value(buff[2], buff[2]));
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/compare.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/compare.pass.cpp
index ed1cb0ccebd2b5..8ab7346800093e 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/compare.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/compare.pass.cpp
@@ -10,17 +10,8 @@
// friend constexpr bool operator==(const iterator& x, const iterator& y)
// requires (equality_comparable<iterator_t<maybe-const<Const, Views>>> && ...);
-// friend constexpr bool operator<(const iterator& x, const iterator& y)
-// requires all-random-access<Const, Views...>;
-// friend constexpr bool operator>(const iterator& x, const iterator& y)
-// requires all-random-access<Const, Views...>;
-// friend constexpr bool operator<=(const iterator& x, const iterator& y)
-// requires all-random-access<Const, Views...>;
-// friend constexpr bool operator>=(const iterator& x, const iterator& y)
-// requires all-random-access<Const, Views...>;
// friend constexpr auto operator<=>(const iterator& x, const iterator& y)
-// requires all-random-access<Const, Views...> &&
-// (three_way_comparable<iterator_t<maybe-const<Const, Views>>> && ...);
+// requires all-random-access<Const, Views...>;
#include <ranges>
#include <compare>
@@ -165,12 +156,7 @@ constexpr bool test() {
using Subrange = std::ranges::subrange<It>;
static_assert(!std::three_way_comparable<It>);
using R = std::ranges::zip_view<Subrange, Subrange>;
-#ifdef _LIBCPP_VERSION
- // libc++ hasn't implemented LWG-3692 "zip_view::iterator's operator<=> is overconstrained"
- static_assert(!std::three_way_comparable<std::ranges::iterator_t<R>>);
-#else
static_assert(std::three_way_comparable<std::ranges::iterator_t<R>>);
-#endif
int a[] = {1, 2, 3, 4};
int b[] = {5, 6, 7, 8, 9};
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/deref.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/deref.pass.cpp
index 569d0409721941..fb58aa28fbdf8d 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/deref.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/deref.pass.cpp
@@ -42,11 +42,7 @@ constexpr bool test() {
auto [x, y] = *it;
assert(&x == &(a[0]));
assert(&y == &(b[0]));
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<decltype(*it), std::pair<int&, double&>>);
-#else
static_assert(std::is_same_v<decltype(*it), std::tuple<int&, double&>>);
-#endif
x = 5;
y = 0.1;
@@ -70,11 +66,7 @@ constexpr bool test() {
auto it = v.begin();
assert(&(std::get<0>(*it)) == &(a[0]));
assert(&(std::get<1>(*it)) == &(a[0]));
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<decltype(*it), std::pair<int&, int const&>>);
-#else
static_assert(std::is_same_v<decltype(*it), std::tuple<int&, int const&>>);
-#endif
}
return true;
}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/member_types.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/member_types.compile.pass.cpp
index c19f6c2b16524f..2f2f0fc4f4e331 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/member_types.compile.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/member_types.compile.pass.cpp
@@ -65,7 +65,7 @@ struct ConstVeryDifferentRange {
void test() {
int buffer[] = {1, 2, 3, 4};
{
- // 2 views should have pair value_type
+ // 2 views should have 2-tuple value_type
// random_access_iterator_tag
std::ranges::zip_view v(buffer, buffer);
using Iter = decltype(v.begin());
@@ -73,11 +73,7 @@ void test() {
static_assert(std::is_same_v<Iter::iterator_concept, std::random_access_iterator_tag>);
static_assert(std::is_same_v<Iter::iterator_category, std::input_iterator_tag>);
static_assert(std::is_same_v<Iter::difference_type, std::ptrdiff_t>);
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<Iter::value_type, std::pair<int, int>>);
-#else
static_assert(std::is_same_v<Iter::value_type, std::tuple<int, int>>);
-#endif
static_assert(HasIterCategory<Iter>);
}
@@ -124,11 +120,7 @@ void test() {
static_assert(std::is_same_v<Iter::iterator_concept, std::random_access_iterator_tag>);
static_assert(std::is_same_v<Iter::iterator_category, std::input_iterator_tag>);
static_assert(std::is_same_v<Iter::difference_type, std::ptrdiff_t>);
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<Iter::value_type, std::pair<int, std::pair<int, int>>>);
-#else
static_assert(std::is_same_v<Iter::value_type, std::tuple<int, std::tuple<int, int>>>);
-#endif
static_assert(HasIterCategory<Iter>);
}
@@ -169,11 +161,7 @@ void test() {
// value_type of multiple views with different value_type
std::ranges::zip_view v{foos, bars};
using Iter = decltype(v.begin());
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<Iter::value_type, std::pair<Foo, Bar>>);
-#else
static_assert(std::is_same_v<Iter::value_type, std::tuple<Foo, Bar>>);
-#endif
}
{
diff --git a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/subscript.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/subscript.pass.cpp
index 1538d763205db1..ba3abfa2a43695 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/subscript.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.zip/iterator/subscript.pass.cpp
@@ -27,11 +27,7 @@ constexpr bool test() {
assert(it[2] == *(it + 2));
assert(it[4] == *(it + 4));
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<decltype(it[2]), std::pair<int&, int>>);
-#else
static_assert(std::is_same_v<decltype(it[2]), std::tuple<int&, int>>);
-#endif
}
{
@@ -42,11 +38,7 @@ constexpr bool test() {
assert(it[2] == *(it + 2));
assert(it[4] == *(it + 4));
-#ifdef _LIBCPP_VERSION // libc++ doesn't implement P2165R4 yet
- static_assert(std::is_same_v<decltype(it[2]), std::pair<int&, int&>>);
-#else
static_assert(std::is_same_v<decltype(it[2]), std::tuple<int&, int&>>);
-#endif
}
{
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