[libcxx-commits] [libcxx] [libc++][ranges] LWG4035: `single_view` should provide `empty` (PR #98371)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Jul 10 12:15:26 PDT 2024
https://github.com/H-G-Hristov updated https://github.com/llvm/llvm-project/pull/98371
>From 7430afd4bd85d9a978e73598b0523aa28e62fb6a Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Tue, 2 Apr 2024 19:27:29 +0300
Subject: [PATCH 1/4] [libc++][ranges] LWG4035: `single_view` should provide
`empty`
Implements: https://wg21.link/LWG4035
---
libcxx/include/__ranges/single_view.h | 2 +
.../range.single.view/empty.pass.cpp | 49 +++++++++++++++++++
2 files changed, 51 insertions(+)
create mode 100644 libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
diff --git a/libcxx/include/__ranges/single_view.h b/libcxx/include/__ranges/single_view.h
index f91c7c3526367..45244f34994d7 100644
--- a/libcxx/include/__ranges/single_view.h
+++ b/libcxx/include/__ranges/single_view.h
@@ -70,6 +70,8 @@ class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS single_view : public view_interface<s
_LIBCPP_HIDE_FROM_ABI constexpr const _Tp* end() const noexcept { return data() + 1; }
+ _LIBCPP_HIDE_FROM_ABI static constexpr bool empty() noexcept { return false; }
+
_LIBCPP_HIDE_FROM_ABI static constexpr size_t size() noexcept { return 1; }
_LIBCPP_HIDE_FROM_ABI constexpr _Tp* data() noexcept { return __value_.operator->(); }
diff --git a/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
new file mode 100644
index 0000000000000..fe73b5ef2b340
--- /dev/null
+++ b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// static constexpr bool empty() noexcept;
+
+#include <cassert>
+#include <concepts>
+#include <ranges>
+#include <utility>
+
+#include "test_macros.h"
+
+struct Empty {};
+struct BigType {
+ char buffer[64] = {10};
+};
+
+template <typename T>
+constexpr void test_empty(T value) {
+ using SingleView = std::ranges::single_view<T>;
+ SingleView sv{value};
+
+ assert(!SingleView::empty());
+ static_assert(noexcept(SingleView::empty()));
+ static_assert(noexcept(std::ranges::empty(sv)));
+ static_assert(noexcept(std::ranges::empty(std::as_const(sv))));
+}
+
+constexpr bool test() {
+ test_empty<int>(92);
+ test_empty<Empty>(Empty{});
+ test_empty<BigType>(BigType{});
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
>From 90764f0eea8afa0dec3e0a48f7f7861357753b80 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Tue, 2 Apr 2024 19:36:44 +0300
Subject: [PATCH 2/4] Minor tweak
---
.../ranges/range.factories/range.single.view/empty.pass.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
index fe73b5ef2b340..ea462e820ec43 100644
--- a/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
+++ b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
@@ -27,7 +27,8 @@ constexpr void test_empty(T value) {
using SingleView = std::ranges::single_view<T>;
SingleView sv{value};
- assert(!SingleView::empty());
+ std::same_as<bool> decltype(auto) result = SingleView::empty();
+ assert(result == false);
static_assert(noexcept(SingleView::empty()));
static_assert(noexcept(std::ranges::empty(sv)));
static_assert(noexcept(std::ranges::empty(std::as_const(sv))));
>From 67d45f0387312d0d1b36c1aa9a5b40d959c90506 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Tue, 2 Apr 2024 20:15:19 +0300
Subject: [PATCH 3/4] Minor tweak
---
.../range.single.view/empty.pass.cpp | 26 ++++++++++++++-----
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
index ea462e820ec43..7e6ff015ea9a4 100644
--- a/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
+++ b/libcxx/test/std/ranges/range.factories/range.single.view/empty.pass.cpp
@@ -25,13 +25,27 @@ struct BigType {
template <typename T>
constexpr void test_empty(T value) {
using SingleView = std::ranges::single_view<T>;
- SingleView sv{value};
- std::same_as<bool> decltype(auto) result = SingleView::empty();
- assert(result == false);
- static_assert(noexcept(SingleView::empty()));
- static_assert(noexcept(std::ranges::empty(sv)));
- static_assert(noexcept(std::ranges::empty(std::as_const(sv))));
+ {
+ std::same_as<bool> decltype(auto) result = SingleView::empty();
+ assert(result == false);
+ static_assert(noexcept(SingleView::empty()));
+ }
+
+ {
+ SingleView sv{value};
+
+ std::same_as<bool> decltype(auto) result = std::ranges::empty(sv);
+ assert(result == false);
+ static_assert(noexcept(std::ranges::empty(sv)));
+ }
+ {
+ const SingleView sv{value};
+
+ std::same_as<bool> decltype(auto) result = std::ranges::empty(sv);
+ assert(result == false);
+ static_assert(noexcept(std::ranges::empty(std::as_const(sv))));
+ }
}
constexpr bool test() {
>From 57029ab082ed818c7e91b244fd498ba7e0ad30fc Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Thu, 4 Apr 2024 23:16:39 +0300
Subject: [PATCH 4/4] Updated status page
---
libcxx/docs/Status/Cxx2cIssues.csv | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
index 540c6a8dd4f47..f9a70aee1bf46 100644
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -53,7 +53,7 @@
"`4025 <https://wg21.link/LWG4025>`__","Move assignment operator of ``std::expected<cv void, E>`` should not be conditionally deleted","Tokyo March 2024","","",""
"`4030 <https://wg21.link/LWG4030>`__","Clarify whether arithmetic expressions in ``[numeric.sat.func]`` are mathematical or C++","Tokyo March 2024","|Nothing To Do|","",""
"`4031 <https://wg21.link/LWG4031>`__","``bad_expected_access<void>`` member functions should be ``noexcept``","Tokyo March 2024","|Complete|","16.0",""
-"`4035 <https://wg21.link/LWG4035>`__","``single_view`` should provide ``empty``","Tokyo March 2024","","","|ranges|"
+"`4035 <https://wg21.link/LWG4035>`__","``single_view`` should provide ``empty``","Tokyo March 2024","|Complete|","19.0","|ranges|"
"`4036 <https://wg21.link/LWG4036>`__","``__alignof_is_defined`` is only implicitly specified in C++ and not yet deprecated","Tokyo March 2024","","",""
"`4037 <https://wg21.link/LWG4037>`__","Static data members of ``ctype_base`` are not yet required to be usable in constant expressions","Tokyo March 2024","","",""
"`4038 <https://wg21.link/LWG4038>`__","``std::text_encoding::aliases_view`` should have constexpr iterators","Tokyo March 2024","","",""
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