[libcxx-commits] [libcxx] [libc++][string] P3044R2: sub-`string_view` from `string` (PR #147095)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Aug 6 09:37:20 PDT 2025
https://github.com/H-G-Hristov updated https://github.com/llvm/llvm-project/pull/147095
>From 0510c784394a21e0a1ec06e15588848912dc568b Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 4 Jul 2025 18:22:03 +0300
Subject: [PATCH 01/13] WIP [libc++][string] P3044R2: sub-`string_view` from
`string`
Implements [P3044R2](https://wg21.link/P3044R2)
- https://github.com/cplusplus/draft/pull/7975
---
libcxx/include/string | 9 +
libcxx/include/string_view | 8 +
.../string.ops/string_substr/subview.pass.cpp | 33 ++++
.../string.view.ops/substr.pass.cpp | 125 --------------
.../string.view.ops/substr_subview.pass.cpp | 158 ++++++++++++++++++
5 files changed, 208 insertions(+), 125 deletions(-)
create mode 100644 libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
delete mode 100644 libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
create mode 100644 libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp
diff --git a/libcxx/include/string b/libcxx/include/string
index 98297d04d0c61..7e8d8fac9f753 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -280,6 +280,8 @@ public:
basic_string substr(size_type pos = 0, size_type n = npos) const; // constexpr in C++20, removed in C++23
basic_string substr(size_type pos = 0, size_type n = npos) const&; // since C++23
constexpr basic_string substr(size_type pos = 0, size_type n = npos) &&; // since C++23
+ constexpr basic_string_view<charT, traits> subview(size_type pos = 0,
+ size_type n = npos) const; // since C++26
void swap(basic_string& str)
noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
allocator_traits<allocator_type>::is_always_equal::value); // C++17, constexpr since C++20
@@ -1752,6 +1754,13 @@ public:
}
# endif
+# if _LIBCPP_STD_VER >= 26
+ _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<_CharT, _Traits>
+ subview(size_type __pos = 0, size_type __n = npos) const {
+ return basic_string_view<_CharT, _Traits>(*this).subview(__pos, __n);
+ }
+# endif
+
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(basic_string& __str)
# if _LIBCPP_STD_VER >= 14
_NOEXCEPT;
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index f86b2722aca6c..952d44123622b 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -130,6 +130,8 @@ namespace std {
size_type copy(charT* s, size_type n, size_type pos = 0) const; // constexpr in C++20
constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
+ constexpr basic_string_view subview(size_type pos = 0,
+ size_type n = npos) const; // freestanding-deleted, since C++26
constexpr int compare(basic_string_view s) const noexcept;
constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
constexpr int compare(size_type pos1, size_type n1,
@@ -465,6 +467,12 @@ public:
: basic_string_view(__assume_valid(), data() + __pos, std::min(__n, size() - __pos));
}
+# if _LIBCPP_STD_VER >= 26
+ _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view subview(size_type __pos = 0, size_type __n = npos) const {
+ return this->substr(__pos, __n);
+ }
+# endif
+
_LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
size_type __rlen = std::min(size(), __sv.size());
int __retval = _Traits::compare(data(), __sv.data(), __rlen);
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
new file mode 100644
index 0000000000000..65418dcb4d7be
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: std-at-least-c++26
+
+// <string>
+
+// constexpr basic_string_view<_CharT, _Traits> subview(size_type __pos = 0, size_type __n = npos) const;
+
+#include <cassert>
+#include <string>
+
+constexpr bool test() {
+ std::string s{"Hello cruel world!"};
+ auto sub = s.subview(6);
+ assert(sub == "cruel world!");
+ auto subsub = sub.subview(0, 5);
+ assert(subsub == "cruel");
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
deleted file mode 100644
index 62b0259c175f8..0000000000000
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
+++ /dev/null
@@ -1,125 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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: !stdlib=libc++ && (c++03 || c++11 || c++14)
-
-// <string_view>
-
-// constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
-
-// Throws: out_of_range if pos > size().
-// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
-// Returns: basic_string_view(data()+pos, rlen).
-
-#include <algorithm>
-#include <cassert>
-#include <cstddef>
-#include <stdexcept>
-#include <string_view>
-
-#include "test_macros.h"
-
-template <typename CharT>
-void test1(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
- std::basic_string_view<CharT> sv1;
-#ifdef TEST_HAS_NO_EXCEPTIONS
- if (pos > sv.size())
- return; // would throw if exceptions were enabled
- sv1 = sv.substr(pos, n);
-#else
- try {
- sv1 = sv.substr(pos, n);
- assert(pos <= sv.size());
- } catch (const std::out_of_range&) {
- assert(pos > sv.size());
- return;
- }
-#endif
- const std::size_t rlen = std::min(n, sv.size() - pos);
- assert(sv1.size() == rlen);
- for (std::size_t i = 0; i < rlen; ++i)
- assert(sv[pos + i] == sv1[i]);
-}
-
-template <typename CharT>
-void test(const CharT* s) {
- typedef std::basic_string_view<CharT> string_view_t;
-
- string_view_t sv1(s);
-
- test1(sv1, 0, 0);
- test1(sv1, 1, 0);
- test1(sv1, 20, 0);
- test1(sv1, sv1.size(), 0);
-
- test1(sv1, 0, 3);
- test1(sv1, 2, 3);
- test1(sv1, 100, 3);
-
- test1(sv1, 0, string_view_t::npos);
- test1(sv1, 2, string_view_t::npos);
- test1(sv1, sv1.size(), string_view_t::npos);
-
- test1(sv1, sv1.size() + 1, 0);
- test1(sv1, sv1.size() + 1, 1);
- test1(sv1, sv1.size() + 1, string_view_t::npos);
-}
-
-int main(int, char**) {
- test("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- test("ABCDE");
- test("a");
- test("");
-
-#ifndef TEST_HAS_NO_WIDE_CHARACTERS
- test(L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- test(L"ABCDE");
- test(L"a");
- test(L"");
-#endif
-
-#if TEST_STD_VER >= 11
- test(u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- test(u"ABCDE");
- test(u"a");
- test(u"");
-
- test(U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- test(U"ABCDE");
- test(U"a");
- test(U"");
-#endif
-
-#if TEST_STD_VER > 11
- {
- constexpr std::string_view sv1{"ABCDE", 5};
-
- {
- constexpr std::string_view sv2 = sv1.substr(0, 3);
- static_assert(sv2.size() == 3, "");
- static_assert(sv2[0] == 'A', "");
- static_assert(sv2[1] == 'B', "");
- static_assert(sv2[2] == 'C', "");
- }
-
- {
- constexpr std::string_view sv2 = sv1.substr(3, 0);
- static_assert(sv2.size() == 0, "");
- }
-
- {
- constexpr std::string_view sv2 = sv1.substr(3, 3);
- static_assert(sv2.size() == 2, "");
- static_assert(sv2[0] == 'D', "");
- static_assert(sv2[1] == 'E', "");
- }
- }
-#endif
-
- return 0;
-}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp
new file mode 100644
index 0000000000000..c40c771db4bae
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp
@@ -0,0 +1,158 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: !stdlib=libc++ && (c++03 || c++11 || c++14)
+
+// <string_view>
+
+// constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
+// constexpr basic_string_view subview(size_type pos = 0,
+// size_type n = npos) const; // freestanding-deleted
+
+// subview is alternative name of substr
+
+// Throws: out_of_range if pos > size().
+// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
+// Returns: basic_string_view(data()+pos, rlen).
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <stdexcept>
+#include <string_view>
+
+#include "test_macros.h"
+
+template <typename CharT>
+struct Test {
+ typedef std::basic_string_view<CharT> (std::basic_string_view<CharT>::*Sub)(
+ typename std::basic_string_view<CharT>::size_type, typename std::basic_string_view<CharT>::size_type) const;
+};
+
+template <typename CharT>
+void testDetail(std::basic_string_view<CharT> sv, typename Test<CharT>::Sub testSub, std::size_t n, size_t pos) {
+ (void)testSub; // Avoid unused parameter warning
+ std::basic_string_view<CharT> sv1;
+#ifdef TEST_HAS_NO_EXCEPTIONS
+ if (pos > sv.size())
+ return; // would throw if exceptions were enabled
+ sv1 = (sv.*testSub)(pos, n);
+#else
+ try {
+ sv1 = (sv.*testSub)(pos, n);
+ assert(pos <= sv.size());
+ } catch (const std::out_of_range&) {
+ assert(pos > sv.size());
+ return;
+ }
+#endif
+ const std::size_t rlen = std::min(n, sv.size() - pos);
+ assert(sv1.size() == rlen);
+ for (std::size_t i = 0; i < rlen; ++i)
+ assert(sv[pos + i] == sv1[i]);
+}
+
+template <typename CharT>
+void testCases(std::basic_string_view<CharT> sv, typename Test<CharT>::Sub testSub) {
+ testDetail(sv, testSub, 0, 0);
+ testDetail(sv, testSub, 1, 0);
+ testDetail(sv, testSub, 20, 0);
+ testDetail(sv, testSub, sv.size(), 0);
+
+ testDetail(sv, testSub, 100, 3);
+
+ testDetail(sv, testSub, 0, std::basic_string_view<CharT>::npos);
+ testDetail(sv, testSub, 2, std::basic_string_view<CharT>::npos);
+ testDetail(sv, testSub, sv.size(), std::basic_string_view<CharT>::npos);
+
+ testDetail(sv, testSub, sv.size() + 1, 0);
+ testDetail(sv, testSub, sv.size() + 1, 1);
+ testDetail(sv, testSub, sv.size() + 1, std::basic_string_view<CharT>::npos);
+}
+
+template <typename CharT>
+void testSubs(const CharT* s) {
+ std::basic_string_view<CharT> sv(s);
+
+ testCases(sv, &std::basic_string_view<CharT>::substr);
+#if TEST_STD_VER >= 26
+ testCases(sv, &std::basic_string_view<CharT>::subview);
+#endif // TEST_STD_VER >= 26
+}
+
+void test() {
+ testSubs("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ testSubs("ABCDE");
+ testSubs("a");
+ testSubs("");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ testSubs(
+ L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ testSubs(L"ABCDE");
+ testSubs(L"a");
+ testSubs(L"");
+#endif
+
+#if TEST_STD_VER >= 11
+ testSubs(
+ u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ testSubs(u"ABCDE");
+ testSubs(u"a");
+ testSubs(u"");
+
+ testSubs(
+ U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ testSubs(U"ABCDE");
+ testSubs(U"a");
+ testSubs(U"");
+#endif
+}
+
+#if TEST_STD_VER >= 14
+template <typename Test<char>::Sub TestSub>
+constexpr void testConstexprDetail() {
+ constexpr std::string_view sv{"ABCDE", 5};
+ {
+ constexpr std::string_view sv2 = (sv.*TestSub)(0, 3);
+
+ static_assert(sv2.size() == 3, "");
+ static_assert(sv2[0] == 'A', "");
+ static_assert(sv2[1] == 'B', "");
+ static_assert(sv2[2] == 'C', "");
+ }
+
+ {
+ constexpr std::string_view sv2 = (sv.*TestSub)(3, 0);
+ static_assert(sv2.size() == 0, "");
+ }
+
+ {
+ constexpr std::string_view sv2 = (sv.*TestSub)(3, 3);
+ static_assert(sv2.size() == 2, "");
+ static_assert(sv2[0] == 'D', "");
+ static_assert(sv2[1] == 'E', "");
+ }
+}
+
+void test_constexpr() {
+ testConstexprDetail<&std::string_view::substr>();
+# if TEST_STD_VER >= 26
+ testConstexprDetail<&std::string_view::subview>();
+# endif
+}
+#endif
+
+int main(int, char**) {
+ test();
+#if TEST_STD_VER >= 14
+ test_constexpr();
+#endif
+
+ return 0;
+}
>From ad5e4107304b3169b54d2cc6904b66734b8512e1 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 4 Jul 2025 21:26:04 +0300
Subject: [PATCH 02/13] Renamed test
---
...ubstr_subview.pass.cpp => substr.pass.cpp} | 43 +++++++++----------
.../string.view.ops/subview.pass.cpp | 20 +++++++++
2 files changed, 41 insertions(+), 22 deletions(-)
rename libcxx/test/std/strings/string.view/string.view.ops/{substr_subview.pass.cpp => substr.pass.cpp} (77%)
create mode 100644 libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
similarity index 77%
rename from libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp
rename to libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
index c40c771db4bae..02755985ead70 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr_subview.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -34,17 +34,16 @@ struct Test {
typename std::basic_string_view<CharT>::size_type, typename std::basic_string_view<CharT>::size_type) const;
};
-template <typename CharT>
-void testDetail(std::basic_string_view<CharT> sv, typename Test<CharT>::Sub testSub, std::size_t n, size_t pos) {
- (void)testSub; // Avoid unused parameter warning
+template <typename CharT, typename Test<CharT>::Sub TestSub>
+void testDetail(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
std::basic_string_view<CharT> sv1;
#ifdef TEST_HAS_NO_EXCEPTIONS
if (pos > sv.size())
return; // would throw if exceptions were enabled
- sv1 = (sv.*testSub)(pos, n);
+ sv1 = (sv.*TestSub)(pos, n);
#else
try {
- sv1 = (sv.*testSub)(pos, n);
+ sv1 = (sv.*TestSub)(pos, n);
assert(pos <= sv.size());
} catch (const std::out_of_range&) {
assert(pos > sv.size());
@@ -57,31 +56,31 @@ void testDetail(std::basic_string_view<CharT> sv, typename Test<CharT>::Sub test
assert(sv[pos + i] == sv1[i]);
}
-template <typename CharT>
-void testCases(std::basic_string_view<CharT> sv, typename Test<CharT>::Sub testSub) {
- testDetail(sv, testSub, 0, 0);
- testDetail(sv, testSub, 1, 0);
- testDetail(sv, testSub, 20, 0);
- testDetail(sv, testSub, sv.size(), 0);
+template <typename CharT, typename Test<CharT>::Sub TestSub>
+void testCases(const CharT* s) {
+ std::basic_string_view<CharT> sv(s);
- testDetail(sv, testSub, 100, 3);
+ testDetail<CharT, TestSub>(sv, 0, 0);
+ testDetail<CharT, TestSub>(sv, 1, 0);
+ testDetail<CharT, TestSub>(sv, 20, 0);
+ testDetail<CharT, TestSub>(sv, sv.size(), 0);
- testDetail(sv, testSub, 0, std::basic_string_view<CharT>::npos);
- testDetail(sv, testSub, 2, std::basic_string_view<CharT>::npos);
- testDetail(sv, testSub, sv.size(), std::basic_string_view<CharT>::npos);
+ testDetail<CharT, TestSub>(sv, 100, 3);
- testDetail(sv, testSub, sv.size() + 1, 0);
- testDetail(sv, testSub, sv.size() + 1, 1);
- testDetail(sv, testSub, sv.size() + 1, std::basic_string_view<CharT>::npos);
+ testDetail<CharT, TestSub>(sv, 0, std::basic_string_view<CharT>::npos);
+ testDetail<CharT, TestSub>(sv, 2, std::basic_string_view<CharT>::npos);
+ testDetail<CharT, TestSub>(sv, sv.size(), std::basic_string_view<CharT>::npos);
+
+ testDetail<CharT, TestSub>(sv, sv.size() + 1, 0);
+ testDetail<CharT, TestSub>(sv, sv.size() + 1, 1);
+ testDetail<CharT, TestSub>(sv, sv.size() + 1, std::basic_string_view<CharT>::npos);
}
template <typename CharT>
void testSubs(const CharT* s) {
- std::basic_string_view<CharT> sv(s);
-
- testCases(sv, &std::basic_string_view<CharT>::substr);
+ testCases<CharT, &std::basic_string_view<CharT>::substr>(s);
#if TEST_STD_VER >= 26
- testCases(sv, &std::basic_string_view<CharT>::subview);
+ testCases<CharT, &std::basic_string_view<CharT>::subview>(s);
#endif // TEST_STD_VER >= 26
}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
new file mode 100644
index 0000000000000..fec258eef4546
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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: std-at-least-c++26
+
+// <string_view>
+
+// constexpr basic_string_view subview(size_type pos = 0,
+// size_type n = npos) const; // freestanding-deleted
+
+int main(int, char**) {
+ // This test is intentionally empty because subview is an alias for substr
+ // and is tested in substr.pass.cpp.
+ return 0;
+}
>From 14162bf3567254c5f4dd8088cd8f8cfeadbf2fe6 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Tue, 22 Jul 2025 22:01:54 +0300
Subject: [PATCH 03/13] LLVM22
---
libcxx/docs/FeatureTestMacroTable.rst | 2 ++
libcxx/docs/ReleaseNotes/22.rst | 1 +
libcxx/docs/Status/Cxx2cPapers.csv | 2 +-
libcxx/include/version | 2 ++
.../string.version.compile.pass.cpp | 30 +++++++++++++++++++
.../string_view.version.compile.pass.cpp | 30 +++++++++++++++++++
.../version.version.compile.pass.cpp | 30 +++++++++++++++++++
.../generate_feature_test_macro_components.py | 5 ++++
8 files changed, 101 insertions(+), 1 deletion(-)
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 61805726a4ff0..63af1ffd77ca4 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -404,6 +404,8 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_string_resize_and_overwrite`` ``202110L``
---------------------------------------------------------- -----------------
+ ``__cpp_lib_string_subview`` ``202506L``
+ ---------------------------------------------------------- -----------------
``__cpp_lib_to_underlying`` ``202102L``
---------------------------------------------------------- -----------------
``__cpp_lib_tuple_like`` *unimplemented*
diff --git a/libcxx/docs/ReleaseNotes/22.rst b/libcxx/docs/ReleaseNotes/22.rst
index 15bf46d44b07f..9361dc0ee8753 100644
--- a/libcxx/docs/ReleaseNotes/22.rst
+++ b/libcxx/docs/ReleaseNotes/22.rst
@@ -39,6 +39,7 @@ Implemented Papers
------------------
- P2321R2: ``zip`` (`Github <https://github.com/llvm/llvm-project/issues/105169>`__) (The paper is partially implemented. ``zip_transform_view`` is implemented in this release)
+- P3044R2: sub-``string_view`` from ``string`` (`Github <https://github.com/llvm/llvm-project/issues/148140>`__)
Improvements and New Features
-----------------------------
diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index febb0c176f9c4..d954c4b9bbdec 100644
--- a/libcxx/docs/Status/Cxx2cPapers.csv
+++ b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -129,7 +129,7 @@
"`P3179R9 <https://wg21.link/P3179R9>`__","Parallel Range Algorithms","2025-06 (Sofia)","","",""
"`P3709R2 <https://wg21.link/P3709R2>`__","Reconsider parallel ``ranges::rotate_copy`` and ``ranges::reverse_copy``","2025-06 (Sofia)","","",""
"`P3641R0 <https://wg21.link/P3641R0>`__","Rename ``std::observable`` to ``std::observable_checkpoint``, and add a feature-test macro","2025-06 (Sofia)","","",""
-"`P3044R2 <https://wg21.link/P3044R2>`__","sub-``string_view`` from ``string``","2025-06 (Sofia)","","",""
+"`P3044R2 <https://wg21.link/P3044R2>`__","sub-``string_view`` from ``string``","2025-06 (Sofia)","|Complete|","22",""
"`P2876R3 <https://wg21.link/P2876R3>`__","Proposal to extend ``std::simd`` with more constructors and accessors","2025-06 (Sofia)","","",""
"`P3480R6 <https://wg21.link/P3480R6>`__","``std::simd`` is a range","2025-06 (Sofia)","","",""
"`P2664R11 <https://wg21.link/P2664R11>`__","Extend ``std::simd`` with permutation API","2025-06 (Sofia)","","",""
diff --git a/libcxx/include/version b/libcxx/include/version
index d98049bd57046..dd874c7d50c74 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -245,6 +245,7 @@ __cpp_lib_starts_ends_with 201711L <string> <string
__cpp_lib_stdatomic_h 202011L <stdatomic.h>
__cpp_lib_string_contains 202011L <string> <string_view>
__cpp_lib_string_resize_and_overwrite 202110L <string>
+__cpp_lib_string_subview 202506L <string> <string_view>
__cpp_lib_string_udls 201304L <string>
__cpp_lib_string_view 202403L <string> <string_view>
201803L // C++20
@@ -535,6 +536,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_stdatomic_h 202011L
# define __cpp_lib_string_contains 202011L
# define __cpp_lib_string_resize_and_overwrite 202110L
+# define __cpp_lib_string_subview 202506L
# define __cpp_lib_to_underlying 202102L
// # define __cpp_lib_tuple_like 202207L
# define __cpp_lib_unreachable 202202L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
index 7236d5d7f2aca..c69c8ed59fb61 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
@@ -60,6 +60,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifdef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should not be defined before c++14"
# endif
@@ -114,6 +118,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++14"
# endif
@@ -177,6 +185,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++17"
# endif
@@ -261,6 +273,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++20"
# endif
@@ -354,6 +370,13 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++23"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++23"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++23"
# endif
@@ -456,6 +479,13 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++26"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++26"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++26"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++26"
# endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
index c7bafb0bf059c..ed13f392b1b7f 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
@@ -40,6 +40,10 @@
# error "__cpp_lib_string_contains should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifdef __cpp_lib_string_view
# error "__cpp_lib_string_view should not be defined before c++17"
# endif
@@ -66,6 +70,10 @@
# error "__cpp_lib_string_contains should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifdef __cpp_lib_string_view
# error "__cpp_lib_string_view should not be defined before c++17"
# endif
@@ -92,6 +100,10 @@
# error "__cpp_lib_string_contains should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_view
# error "__cpp_lib_string_view should be defined in c++17"
# endif
@@ -136,6 +148,10 @@
# error "__cpp_lib_string_contains should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_view
# error "__cpp_lib_string_view should be defined in c++20"
# endif
@@ -183,6 +199,13 @@
# error "__cpp_lib_string_contains should have the value 202011L in c++23"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++23"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# endif
+
# ifndef __cpp_lib_string_view
# error "__cpp_lib_string_view should be defined in c++23"
# endif
@@ -239,6 +262,13 @@
# error "__cpp_lib_string_contains should have the value 202011L in c++26"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++26"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++26"
+# endif
+
# ifndef __cpp_lib_string_view
# error "__cpp_lib_string_view should be defined in c++26"
# endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index 962688e06188a..0df86fbb825e4 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -820,6 +820,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifdef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should not be defined before c++14"
# endif
@@ -1775,6 +1779,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++14"
# endif
@@ -2916,6 +2924,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++17"
# endif
@@ -4330,6 +4342,10 @@
# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++23"
# endif
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++20"
# endif
@@ -5978,6 +5994,13 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++23"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++23"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++23"
# endif
@@ -7947,6 +7970,13 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++26"
# endif
+# ifndef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should be defined in c++26"
+# endif
+# if __cpp_lib_string_subview != 202506L
+# error "__cpp_lib_string_subview should have the value 202506L in c++26"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++26"
# endif
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index fe175fd758726..75cc8705ecffb 100644
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1337,6 +1337,11 @@ def add_version_header(tc):
"values": {"c++23": 202110},
"headers": ["string"],
},
+ {
+ "name": "__cpp_lib_string_subview",
+ "values": {"c++23": 202506},
+ "headers": ["string", "string_view"],
+ },
{
"name": "__cpp_lib_string_udls",
"values": {"c++14": 201304},
>From f9efc16976cf10bdd2941e0d5061db5caa793005 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 23 Jul 2025 01:21:11 +0300
Subject: [PATCH 04/13] Updated test
---
.../string.ops/string_substr/subview.pass.cpp | 47 +++++++++++++++++--
1 file changed, 42 insertions(+), 5 deletions(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 65418dcb4d7be..4fd2a4ceb5f7a 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -15,12 +15,49 @@
#include <cassert>
#include <string>
+#include "asan_testing.h"
+#include "constexpr_char_traits.h"
+#include "make_string.h"
+#include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+#define CS(S) MAKE_CSTRING(CharT, S)
+
+template <typename CharT, typename TraitsT, typename AllocT>
+constexpr void test() {
+ std::basic_string<CharT, TraitsT, AllocT> s{CS("Hello cruel world!"), AllocT{}};
+
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(6);
+ assert(sv == CS("cruel world!"));
+
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) subsv = sv.subview(0, 5);
+ assert(subsv == CS("cruel"));
+}
+
+template <typename CharT>
+constexpr void test() {
+ test<CharT, std::char_traits<CharT>, std::allocator<CharT>>();
+ test<CharT, std::char_traits<CharT>, min_allocator<CharT>>();
+ test<CharT, std::char_traits<CharT>, safe_allocator<CharT>>();
+ test<CharT, std::char_traits<CharT>, test_allocator<CharT>>();
+
+ test<CharT, constexpr_char_traits<CharT>, std::allocator<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>, min_allocator<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>, safe_allocator<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>, test_allocator<CharT>>();
+}
+
constexpr bool test() {
- std::string s{"Hello cruel world!"};
- auto sub = s.subview(6);
- assert(sub == "cruel world!");
- auto subsub = sub.subview(0, 5);
- assert(subsub == "cruel");
+ test<char>();
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test<wchar_t>();
+#endif
+#ifndef TEST_HAS_NO_CHAR8_T
+ test<char8_t>();
+#endif
+ test<char16_t>();
+ test<char32_t>();
return true;
}
>From 3dbebaee031930e6658b8748cd670f566a4ccabd Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 23 Jul 2025 09:03:19 +0300
Subject: [PATCH 05/13] Fix the test!!!
---
.../string.ops/string_substr/subview.pass.cpp | 28 +++++++++++++++----
1 file changed, 23 insertions(+), 5 deletions(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 4fd2a4ceb5f7a..63beedf829039 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -15,7 +15,6 @@
#include <cassert>
#include <string>
-#include "asan_testing.h"
#include "constexpr_char_traits.h"
#include "make_string.h"
#include "min_allocator.h"
@@ -28,11 +27,30 @@ template <typename CharT, typename TraitsT, typename AllocT>
constexpr void test() {
std::basic_string<CharT, TraitsT, AllocT> s{CS("Hello cruel world!"), AllocT{}};
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(6);
- assert(sv == CS("cruel world!"));
+ { // With a default position and a character length.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview();
+ assert(sv == CS("Hello cruel world!"));
+ }
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) subsv = sv.subview(0, 5);
- assert(subsv == CS("cruel"));
+ { // With a explict position and a character length.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(6, 5);
+ assert(sv == CS("cruel"));
+ }
+
+ { // From the beginning of the string with a explicit character length.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, 5);
+ assert(sv == CS("Hello"));
+ }
+
+ { // To the end of string with the default character length.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(12);
+ assert(sv == CS("world!"));
+ }
+
+ { // From the beginning to the end of the string with explicit values.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, s.size());
+ assert(sv == CS("Hello cruel world!"));
+ }
}
template <typename CharT>
>From 43e3c15add04ea529f48043f5c50fecab3eddc08 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Sat, 2 Aug 2025 07:35:28 +0300
Subject: [PATCH 06/13] Address review comments
---
.../string.ops/string_substr/subview.pass.cpp | 40 +++++++++++++++++++
.../string.view.ops/substr.pass.cpp | 2 +-
2 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 63beedf829039..20443f2f479cf 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -14,6 +14,7 @@
#include <cassert>
#include <string>
+#include <utility>
#include "constexpr_char_traits.h"
#include "make_string.h"
@@ -29,28 +30,67 @@ constexpr void test() {
{ // With a default position and a character length.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview();
+
assert(sv == CS("Hello cruel world!"));
+ // Also check if subview() is a const-qualified.
+ assert(std::as_const(s).subview() == CS("Hello cruel world!"));
}
{ // With a explict position and a character length.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(6, 5);
+
assert(sv == CS("cruel"));
}
{ // From the beginning of the string with a explicit character length.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, 5);
+
assert(sv == CS("Hello"));
}
{ // To the end of string with the default character length.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(12);
+
assert(sv == CS("world!"));
}
{ // From the beginning to the end of the string with explicit values.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, s.size());
+
assert(sv == CS("Hello cruel world!"));
}
+
+ // Test if exceptions are thrown correctly.
+#ifndef TEST_HAS_NO_EXCEPTIONS
+ if (!std::is_constant_evaluated()) {
+ { // With a position that is out of range.
+ try {
+ s.subview(s.size() + 1);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
+
+ { // With a position that is out of range and a 0 character length.
+ try {
+ s.subview(s.size() + 1, 0);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
+
+ { // With a position that is out of range and a some character length.
+ try {
+ s.subview(s.size() + 1, 1);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
+ }
+#endif
}
template <typename CharT>
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
index 02755985ead70..8f488cdf54c6e 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -81,7 +81,7 @@ void testSubs(const CharT* s) {
testCases<CharT, &std::basic_string_view<CharT>::substr>(s);
#if TEST_STD_VER >= 26
testCases<CharT, &std::basic_string_view<CharT>::subview>(s);
-#endif // TEST_STD_VER >= 26
+#endif
}
void test() {
>From b6c564a724b30fade5a63cdb0160b999d73ec6d5 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 08:36:13 +0300
Subject: [PATCH 07/13] Addressed comments
---
.../string.ops/string_substr/subview.pass.cpp | 35 ++-
.../string.view.ops/substr.pass.cpp | 219 ++++++++++++------
2 files changed, 161 insertions(+), 93 deletions(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 20443f2f479cf..ab74624ccb393 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -29,6 +29,8 @@ constexpr void test() {
std::basic_string<CharT, TraitsT, AllocT> s{CS("Hello cruel world!"), AllocT{}};
{ // With a default position and a character length.
+
+ // Check it the return type of subview() is correct.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview();
assert(sv == CS("Hello cruel world!"));
@@ -36,28 +38,19 @@ constexpr void test() {
assert(std::as_const(s).subview() == CS("Hello cruel world!"));
}
- { // With a explict position and a character length.
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(6, 5);
-
- assert(sv == CS("cruel"));
- }
-
- { // From the beginning of the string with a explicit character length.
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, 5);
+ { // Check with different position and length.
- assert(sv == CS("Hello"));
- }
-
- { // To the end of string with the default character length.
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(12);
+ // With a explict position and a character length.
+ assert(s.subview(6, 5) == CS("cruel"));
- assert(sv == CS("world!"));
- }
+ // From the beginning of the string with a explicit character length.
+ assert(sv = s.subview(0, 5) == CS("Hello"));
- { // From the beginning to the end of the string with explicit values.
- std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview(0, s.size());
+ // To the end of string with the default character length.
+ assert(subview(12) == CS("world!"));
- assert(sv == CS("Hello cruel world!"));
+ // From the beginning to the end of the string with explicit values.
+ assert(subview(0, s.size() == CS("Hello cruel world!"));
}
// Test if exceptions are thrown correctly.
@@ -68,7 +61,7 @@ constexpr void test() {
s.subview(s.size() + 1);
assert(false && "Expected std::out_of_range exception");
} catch (const std::out_of_range&) {
- // Expected exception
+ // Expected exception...
}
}
@@ -77,7 +70,7 @@ constexpr void test() {
s.subview(s.size() + 1, 0);
assert(false && "Expected std::out_of_range exception");
} catch (const std::out_of_range&) {
- // Expected exception
+ // Expected exception...
}
}
@@ -86,7 +79,7 @@ constexpr void test() {
s.subview(s.size() + 1, 1);
assert(false && "Expected std::out_of_range exception");
} catch (const std::out_of_range&) {
- // Expected exception
+ // Expected exception...
}
}
}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
index 8f488cdf54c6e..6ed46452365a5 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -20,36 +20,41 @@
// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
// Returns: basic_string_view(data()+pos, rlen).
-#include <algorithm>
-#include <cassert>
-#include <cstddef>
-#include <stdexcept>
-#include <string_view>
+#if 0
+# include <algorithm>
+# include <cassert>
+# include <string_view>
-#include "test_macros.h"
+# include "make_string.h"
+# include "test_macros.h"
+
+# define CS(S) MAKE_CSTRING(CharT, S)
template <typename CharT>
struct Test {
typedef std::basic_string_view<CharT> (std::basic_string_view<CharT>::*Sub)(
- typename std::basic_string_view<CharT>::size_type, typename std::basic_string_view<CharT>::size_type) const;
+ typename std::basic_string_view<CharT>::size_type = 0, typename std::basic_string_view<CharT>::size_type = npos) const;
};
+
template <typename CharT, typename Test<CharT>::Sub TestSub>
-void testDetail(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
+TEST_CONSTEXPR_CXX14 void testDetail(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
std::basic_string_view<CharT> sv1;
-#ifdef TEST_HAS_NO_EXCEPTIONS
+# ifdef TEST_HAS_NO_EXCEPTIONS
if (pos > sv.size())
return; // would throw if exceptions were enabled
sv1 = (sv.*TestSub)(pos, n);
-#else
- try {
- sv1 = (sv.*TestSub)(pos, n);
- assert(pos <= sv.size());
- } catch (const std::out_of_range&) {
- assert(pos > sv.size());
- return;
+# else
+ if (!TEST_IS_CONSTANT_EVALUATED) {
+ try {
+ sv1 = (sv.*TestSub)(pos, n);
+ assert(pos <= sv.size());
+ } catch (const std::out_of_range&) {
+ assert(pos > sv.size());
+ return;
+ }
}
-#endif
+# endif
const std::size_t rlen = std::min(n, sv.size() - pos);
assert(sv1.size() == rlen);
for (std::size_t i = 0; i < rlen; ++i)
@@ -57,7 +62,7 @@ void testDetail(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
}
template <typename CharT, typename Test<CharT>::Sub TestSub>
-void testCases(const CharT* s) {
+TEST_CONSTEXPR_CXX14 void testCases(const CharT* s) {
std::basic_string_view<CharT> sv(s);
testDetail<CharT, TestSub>(sv, 0, 0);
@@ -71,87 +76,157 @@ void testCases(const CharT* s) {
testDetail<CharT, TestSub>(sv, 2, std::basic_string_view<CharT>::npos);
testDetail<CharT, TestSub>(sv, sv.size(), std::basic_string_view<CharT>::npos);
+ // Test if exceptions are thrown correctly.
testDetail<CharT, TestSub>(sv, sv.size() + 1, 0);
testDetail<CharT, TestSub>(sv, sv.size() + 1, 1);
testDetail<CharT, TestSub>(sv, sv.size() + 1, std::basic_string_view<CharT>::npos);
}
template <typename CharT>
-void testSubs(const CharT* s) {
+TEST_CONSTEXPR_CXX14 void testSubs(const CharT* s) {
testCases<CharT, &std::basic_string_view<CharT>::substr>(s);
-#if TEST_STD_VER >= 26
+# if TEST_STD_VER >= 26
testCases<CharT, &std::basic_string_view<CharT>::subview>(s);
-#endif
+# endif
}
-void test() {
- testSubs("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- testSubs("ABCDE");
- testSubs("a");
- testSubs("");
+# define CS(S) MAKE_CSTRING(CharT, S)
-#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+template <typename CharT>
+TEST_CONSTEXPR_CXX14 void test() {
testSubs(
- L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- testSubs(L"ABCDE");
- testSubs(L"a");
- testSubs(L"");
-#endif
+ CS("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE"));
+ testSubs(CS("ABCDE"));
+ testSubs(CS("a"));
+ testSubs(CS(""));
+}
-#if TEST_STD_VER >= 11
- testSubs(
- u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- testSubs(u"ABCDE");
- testSubs(u"a");
- testSubs(u"");
+TEST_CONSTEXPR_CXX14 bool test() {
+ test<char>();
+# ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test<wchar_t>();
+# endif
+# if TEST_STD_VER >= 11
+# ifndef TEST_HAS_NO_CHAR8_T
+ test<char8_t>();
+# endif
+ test<char16_t>();
+ test<char32_t>();
+# endif
- testSubs(
- U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
- testSubs(U"ABCDE");
- testSubs(U"a");
- testSubs(U"");
-#endif
+ return true;
}
-#if TEST_STD_VER >= 14
-template <typename Test<char>::Sub TestSub>
-constexpr void testConstexprDetail() {
- constexpr std::string_view sv{"ABCDE", 5};
- {
- constexpr std::string_view sv2 = (sv.*TestSub)(0, 3);
-
- static_assert(sv2.size() == 3, "");
- static_assert(sv2[0] == 'A', "");
- static_assert(sv2[1] == 'B', "");
- static_assert(sv2[2] == 'C', "");
- }
+int main(int, char**) {
+ test();
+# if TEST_STD_VER >= 14
+ // static_assert(test());
+# endif
- {
- constexpr std::string_view sv2 = (sv.*TestSub)(3, 0);
- static_assert(sv2.size() == 0, "");
- }
+ return 0;
+}
+#endif
+
+#include <cassert>
+#include <string>
+#include <utility>
+
+#include "constexpr_char_traits.h"
+#include "make_string.h"
+#include "test_macros.h"
+
+#define CS(S) MAKE_CSTRING(CharT, S)
+
+template <typename CharT, typename TraitsT>
+struct Test {
+ typedef std::basic_string_view<CharT, TraitsT> (std::basic_string_view<CharT, TraitsT>::*Sub)(
+ typename std::basic_string_view<CharT, TraitsT>::size_type,
+ typename std::basic_string_view<CharT, TraitsT>::size_type) const;
+};
- {
- constexpr std::string_view sv2 = (sv.*TestSub)(3, 3);
- static_assert(sv2.size() == 2, "");
- static_assert(sv2[0] == 'D', "");
- static_assert(sv2[1] == 'E', "");
+template <typename CharT, typename TraitsT, typename Test<CharT, TraitsT>::Sub TestSub>
+TEST_CONSTEXPR_CXX14 void test() {
+ const std::basic_string_view<CharT, TraitsT> sv = CS("Hello cruel world!");
+
+ // With a default position and a character length.
+ assert((sv.*TestSub)(0, std::basic_string_view<CharT, TraitsT>::npos) == CS("Hello cruel world!"));
+
+ // With a explict position and a character length.
+ assert((sv.*TestSub)(6, 5) == CS("cruel"));
+
+ // From the beginning of the string with a explicit character length.
+ assert((sv.*TestSub)(0, 5) == CS("Hello"));
+
+ // To the end of string with the default character length.
+ assert((sv.*TestSub)(12, std::basic_string_view<CharT, TraitsT>::npos) == CS("world!"));
+
+ // From the beginning to the end of the string with explicit values.
+ assert((sv.*TestSub)(0, sv.size()) == CS("Hello cruel world!"));
+
+ // Test if exceptions are thrown correctly.
+#ifndef TEST_HAS_NO_EXCEPTIONS
+ if (!TEST_IS_CONSTANT_EVALUATED) {
+ { // With a position that is out of range.
+ try {
+ (sv.*TestSub)(sv.size() + 1, std::basic_string_view<CharT, TraitsT>::npos);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
+
+ { // With a position that is out of range and a 0 character length.
+ try {
+ (sv.*TestSub)(sv.size() + 1, 0);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
+
+ { // With a position that is out of range and a some character length.
+ try {
+ (sv.*TestSub)(sv.size() + 1, 1);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception
+ }
+ }
}
+#endif
}
-void test_constexpr() {
- testConstexprDetail<&std::string_view::substr>();
-# if TEST_STD_VER >= 26
- testConstexprDetail<&std::string_view::subview>();
-# endif
+template <typename CharT>
+TEST_CONSTEXPR_CXX14 void test() {
+ ASSERT_SAME_TYPE(std::basic_string_view<CharT>, decltype(std::declval<std::basic_string_view<CharT> >().substr()));
+ test<CharT, std::char_traits<CharT>, &std::basic_string_view<CharT, std::char_traits<CharT> >::substr>();
+ test<CharT, constexpr_char_traits<CharT>, &std::basic_string_view<CharT, constexpr_char_traits<CharT> >::substr>();
+#if TEST_STD_VER >= 26
+ ASSERT_SAME_TYPE(std::basic_string_view<CharT>, decltype(std::declval<std::basic_string_view<CharT> >().subview()));
+ test<CharT, std::char_traits<CharT>, &std::basic_string_view<CharT, std::char_traits<CharT>>::subview>();
+ test<CharT, constexpr_char_traits<CharT>, &std::basic_string_view<CharT, constexpr_char_traits<CharT> >::subview>();
+#endif
}
+
+TEST_CONSTEXPR_CXX14 bool test() {
+ test<char>();
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test<wchar_t>();
+#endif
+#ifndef TEST_HAS_NO_CHAR8_T
+ test<char8_t>();
#endif
+ test<char16_t>();
+ test<char32_t>();
+
+ return true;
+}
int main(int, char**) {
test();
#if TEST_STD_VER >= 14
- test_constexpr();
+ static_assert(test());
#endif
return 0;
-}
+}
\ No newline at end of file
>From 14827405227f450e0bc0b6d69b8419254afec175 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 09:07:06 +0300
Subject: [PATCH 08/13] Addressed comments
---
.../string.ops/string_substr/subview.pass.cpp | 12 +-
.../string.view.ops/substr.pass.cpp | 249 +++++-------------
.../string.view.ops/subview.pass.cpp | 104 +++++++-
3 files changed, 179 insertions(+), 186 deletions(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index ab74624ccb393..8d714fff8cd3b 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -30,12 +30,12 @@ constexpr void test() {
{ // With a default position and a character length.
+ // Also check if subview() is a const-qualified.
+ assert(std::as_const(s).subview() == CS("Hello cruel world!"));
+
// Check it the return type of subview() is correct.
std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) sv = s.subview();
-
assert(sv == CS("Hello cruel world!"));
- // Also check if subview() is a const-qualified.
- assert(std::as_const(s).subview() == CS("Hello cruel world!"));
}
{ // Check with different position and length.
@@ -44,13 +44,13 @@ constexpr void test() {
assert(s.subview(6, 5) == CS("cruel"));
// From the beginning of the string with a explicit character length.
- assert(sv = s.subview(0, 5) == CS("Hello"));
+ assert(s.subview(0, 5) == CS("Hello"));
// To the end of string with the default character length.
- assert(subview(12) == CS("world!"));
+ assert(s.subview(12) == CS("world!"));
// From the beginning to the end of the string with explicit values.
- assert(subview(0, s.size() == CS("Hello cruel world!"));
+ assert(s.subview(0, s.size()) == CS("Hello cruel world!"));
}
// Test if exceptions are thrown correctly.
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
index 6ed46452365a5..62b0259c175f8 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -11,222 +11,115 @@
// <string_view>
// constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
-// constexpr basic_string_view subview(size_type pos = 0,
-// size_type n = npos) const; // freestanding-deleted
-
-// subview is alternative name of substr
// Throws: out_of_range if pos > size().
// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
// Returns: basic_string_view(data()+pos, rlen).
-#if 0
-# include <algorithm>
-# include <cassert>
-# include <string_view>
-
-# include "make_string.h"
-# include "test_macros.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <stdexcept>
+#include <string_view>
-# define CS(S) MAKE_CSTRING(CharT, S)
+#include "test_macros.h"
template <typename CharT>
-struct Test {
- typedef std::basic_string_view<CharT> (std::basic_string_view<CharT>::*Sub)(
- typename std::basic_string_view<CharT>::size_type = 0, typename std::basic_string_view<CharT>::size_type = npos) const;
-};
-
-
-template <typename CharT, typename Test<CharT>::Sub TestSub>
-TEST_CONSTEXPR_CXX14 void testDetail(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
+void test1(std::basic_string_view<CharT> sv, std::size_t n, size_t pos) {
std::basic_string_view<CharT> sv1;
-# ifdef TEST_HAS_NO_EXCEPTIONS
+#ifdef TEST_HAS_NO_EXCEPTIONS
if (pos > sv.size())
return; // would throw if exceptions were enabled
- sv1 = (sv.*TestSub)(pos, n);
-# else
- if (!TEST_IS_CONSTANT_EVALUATED) {
- try {
- sv1 = (sv.*TestSub)(pos, n);
- assert(pos <= sv.size());
- } catch (const std::out_of_range&) {
- assert(pos > sv.size());
- return;
- }
+ sv1 = sv.substr(pos, n);
+#else
+ try {
+ sv1 = sv.substr(pos, n);
+ assert(pos <= sv.size());
+ } catch (const std::out_of_range&) {
+ assert(pos > sv.size());
+ return;
}
-# endif
+#endif
const std::size_t rlen = std::min(n, sv.size() - pos);
assert(sv1.size() == rlen);
for (std::size_t i = 0; i < rlen; ++i)
assert(sv[pos + i] == sv1[i]);
}
-template <typename CharT, typename Test<CharT>::Sub TestSub>
-TEST_CONSTEXPR_CXX14 void testCases(const CharT* s) {
- std::basic_string_view<CharT> sv(s);
+template <typename CharT>
+void test(const CharT* s) {
+ typedef std::basic_string_view<CharT> string_view_t;
- testDetail<CharT, TestSub>(sv, 0, 0);
- testDetail<CharT, TestSub>(sv, 1, 0);
- testDetail<CharT, TestSub>(sv, 20, 0);
- testDetail<CharT, TestSub>(sv, sv.size(), 0);
+ string_view_t sv1(s);
- testDetail<CharT, TestSub>(sv, 100, 3);
+ test1(sv1, 0, 0);
+ test1(sv1, 1, 0);
+ test1(sv1, 20, 0);
+ test1(sv1, sv1.size(), 0);
- testDetail<CharT, TestSub>(sv, 0, std::basic_string_view<CharT>::npos);
- testDetail<CharT, TestSub>(sv, 2, std::basic_string_view<CharT>::npos);
- testDetail<CharT, TestSub>(sv, sv.size(), std::basic_string_view<CharT>::npos);
+ test1(sv1, 0, 3);
+ test1(sv1, 2, 3);
+ test1(sv1, 100, 3);
- // Test if exceptions are thrown correctly.
- testDetail<CharT, TestSub>(sv, sv.size() + 1, 0);
- testDetail<CharT, TestSub>(sv, sv.size() + 1, 1);
- testDetail<CharT, TestSub>(sv, sv.size() + 1, std::basic_string_view<CharT>::npos);
-}
+ test1(sv1, 0, string_view_t::npos);
+ test1(sv1, 2, string_view_t::npos);
+ test1(sv1, sv1.size(), string_view_t::npos);
-template <typename CharT>
-TEST_CONSTEXPR_CXX14 void testSubs(const CharT* s) {
- testCases<CharT, &std::basic_string_view<CharT>::substr>(s);
-# if TEST_STD_VER >= 26
- testCases<CharT, &std::basic_string_view<CharT>::subview>(s);
-# endif
-}
-
-# define CS(S) MAKE_CSTRING(CharT, S)
-
-template <typename CharT>
-TEST_CONSTEXPR_CXX14 void test() {
- testSubs(
- CS("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE"));
- testSubs(CS("ABCDE"));
- testSubs(CS("a"));
- testSubs(CS(""));
-}
-
-TEST_CONSTEXPR_CXX14 bool test() {
- test<char>();
-# ifndef TEST_HAS_NO_WIDE_CHARACTERS
- test<wchar_t>();
-# endif
-# if TEST_STD_VER >= 11
-# ifndef TEST_HAS_NO_CHAR8_T
- test<char8_t>();
-# endif
- test<char16_t>();
- test<char32_t>();
-# endif
-
- return true;
+ test1(sv1, sv1.size() + 1, 0);
+ test1(sv1, sv1.size() + 1, 1);
+ test1(sv1, sv1.size() + 1, string_view_t::npos);
}
int main(int, char**) {
- test();
-# if TEST_STD_VER >= 14
- // static_assert(test());
-# endif
+ test("ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ test("ABCDE");
+ test("a");
+ test("");
- return 0;
-}
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test(L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ test(L"ABCDE");
+ test(L"a");
+ test(L"");
#endif
-#include <cassert>
-#include <string>
-#include <utility>
-
-#include "constexpr_char_traits.h"
-#include "make_string.h"
-#include "test_macros.h"
+#if TEST_STD_VER >= 11
+ test(u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ test(u"ABCDE");
+ test(u"a");
+ test(u"");
-#define CS(S) MAKE_CSTRING(CharT, S)
-
-template <typename CharT, typename TraitsT>
-struct Test {
- typedef std::basic_string_view<CharT, TraitsT> (std::basic_string_view<CharT, TraitsT>::*Sub)(
- typename std::basic_string_view<CharT, TraitsT>::size_type,
- typename std::basic_string_view<CharT, TraitsT>::size_type) const;
-};
-
-template <typename CharT, typename TraitsT, typename Test<CharT, TraitsT>::Sub TestSub>
-TEST_CONSTEXPR_CXX14 void test() {
- const std::basic_string_view<CharT, TraitsT> sv = CS("Hello cruel world!");
-
- // With a default position and a character length.
- assert((sv.*TestSub)(0, std::basic_string_view<CharT, TraitsT>::npos) == CS("Hello cruel world!"));
-
- // With a explict position and a character length.
- assert((sv.*TestSub)(6, 5) == CS("cruel"));
-
- // From the beginning of the string with a explicit character length.
- assert((sv.*TestSub)(0, 5) == CS("Hello"));
-
- // To the end of string with the default character length.
- assert((sv.*TestSub)(12, std::basic_string_view<CharT, TraitsT>::npos) == CS("world!"));
+ test(U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE");
+ test(U"ABCDE");
+ test(U"a");
+ test(U"");
+#endif
- // From the beginning to the end of the string with explicit values.
- assert((sv.*TestSub)(0, sv.size()) == CS("Hello cruel world!"));
+#if TEST_STD_VER > 11
+ {
+ constexpr std::string_view sv1{"ABCDE", 5};
- // Test if exceptions are thrown correctly.
-#ifndef TEST_HAS_NO_EXCEPTIONS
- if (!TEST_IS_CONSTANT_EVALUATED) {
- { // With a position that is out of range.
- try {
- (sv.*TestSub)(sv.size() + 1, std::basic_string_view<CharT, TraitsT>::npos);
- assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception
- }
+ {
+ constexpr std::string_view sv2 = sv1.substr(0, 3);
+ static_assert(sv2.size() == 3, "");
+ static_assert(sv2[0] == 'A', "");
+ static_assert(sv2[1] == 'B', "");
+ static_assert(sv2[2] == 'C', "");
}
- { // With a position that is out of range and a 0 character length.
- try {
- (sv.*TestSub)(sv.size() + 1, 0);
- assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception
- }
+ {
+ constexpr std::string_view sv2 = sv1.substr(3, 0);
+ static_assert(sv2.size() == 0, "");
}
- { // With a position that is out of range and a some character length.
- try {
- (sv.*TestSub)(sv.size() + 1, 1);
- assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception
- }
+ {
+ constexpr std::string_view sv2 = sv1.substr(3, 3);
+ static_assert(sv2.size() == 2, "");
+ static_assert(sv2[0] == 'D', "");
+ static_assert(sv2[1] == 'E', "");
}
}
#endif
-}
-
-template <typename CharT>
-TEST_CONSTEXPR_CXX14 void test() {
- ASSERT_SAME_TYPE(std::basic_string_view<CharT>, decltype(std::declval<std::basic_string_view<CharT> >().substr()));
- test<CharT, std::char_traits<CharT>, &std::basic_string_view<CharT, std::char_traits<CharT> >::substr>();
- test<CharT, constexpr_char_traits<CharT>, &std::basic_string_view<CharT, constexpr_char_traits<CharT> >::substr>();
-#if TEST_STD_VER >= 26
- ASSERT_SAME_TYPE(std::basic_string_view<CharT>, decltype(std::declval<std::basic_string_view<CharT> >().subview()));
- test<CharT, std::char_traits<CharT>, &std::basic_string_view<CharT, std::char_traits<CharT>>::subview>();
- test<CharT, constexpr_char_traits<CharT>, &std::basic_string_view<CharT, constexpr_char_traits<CharT> >::subview>();
-#endif
-}
-
-TEST_CONSTEXPR_CXX14 bool test() {
- test<char>();
-#ifndef TEST_HAS_NO_WIDE_CHARACTERS
- test<wchar_t>();
-#endif
-#ifndef TEST_HAS_NO_CHAR8_T
- test<char8_t>();
-#endif
- test<char16_t>();
- test<char32_t>();
-
- return true;
-}
-
-int main(int, char**) {
- test();
-#if TEST_STD_VER >= 14
- static_assert(test());
-#endif
return 0;
-}
\ No newline at end of file
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
index fec258eef4546..57947bd0e9ecd 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
@@ -13,8 +13,108 @@
// constexpr basic_string_view subview(size_type pos = 0,
// size_type n = npos) const; // freestanding-deleted
+#include <cassert>
+#include <string>
+#include <utility>
+
+#include "constexpr_char_traits.h"
+#include "make_string.h"
+#include "test_macros.h"
+
+#define CS(S) MAKE_CSTRING(CharT, S)
+
+template <typename CharT, typename TraitsT>
+constexpr void test() {
+ std::basic_string_view<CharT, TraitsT> sv{CS("Hello cruel world!")};
+
+ { // With a default position and a character length.
+
+ // Check if subview() is a const-qualified.
+ assert(std::as_const(sv).subview() == CS("Hello cruel world!"));
+
+ // Check if the return type of subview() is correct.
+ std::same_as<std::basic_string_view<CharT, TraitsT>> decltype(auto) subsv = sv.subview();
+ assert(subsv == CS("Hello cruel world!"));
+ }
+
+ { // Check with different position and length.
+
+ // With a explict position and a character length.
+ assert(sv.subview(6, 5) == CS("cruel"));
+
+ // From the beginning of the string with a explicit character length.
+ assert(sv.subview(0, 5) == CS("Hello"));
+
+ // To the end of string with the default character length.
+ assert(sv.subview(12) == CS("world!"));
+
+ // From the beginning to the end of the string with explicit values.
+ assert(sv.subview(0, sv.size()) == CS("Hello cruel world!"));
+ }
+
+ // Test if exceptions are thrown correctly.
+#ifndef TEST_HAS_NO_EXCEPTIONS
+ if (!std::is_constant_evaluated()) {
+ { // With a position that is out of range.
+ try {
+ sv.subview(sv.size() + 1);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception...
+ }
+ }
+
+ { // With a position that is out of range and a 0 character length.
+ try {
+ sv.subview(sv.size() + 1, 0);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception...
+ }
+ }
+
+ { // With a position that is out of range and a some character length.
+ try {
+ sv.subview(sv.size() + 1, 1);
+ assert(false && "Expected std::out_of_range exception");
+ } catch (const std::out_of_range&) {
+ // Expected exception...
+ }
+ }
+ }
+#endif
+}
+
+template <typename CharT>
+constexpr void test() {
+ test<CharT, std::char_traits<CharT>>();
+ test<CharT, std::char_traits<CharT>>();
+ test<CharT, std::char_traits<CharT>>();
+ test<CharT, std::char_traits<CharT>>();
+
+ test<CharT, constexpr_char_traits<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>>();
+ test<CharT, constexpr_char_traits<CharT>>();
+}
+
+constexpr bool test() {
+ test<char>();
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test<wchar_t>();
+#endif
+#ifndef TEST_HAS_NO_CHAR8_T
+ test<char8_t>();
+#endif
+ test<char16_t>();
+ test<char32_t>();
+
+ return true;
+}
+
int main(int, char**) {
- // This test is intentionally empty because subview is an alias for substr
- // and is tested in substr.pass.cpp.
+ test();
+ static_assert(test());
+
return 0;
}
>From 568336fa15ff138f85a7de9ef4e4229d5820b90b Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 17:20:12 +0300
Subject: [PATCH 09/13] Fix CI
---
.../basic.string/string.ops/string_substr/subview.pass.cpp | 2 ++
.../std/strings/string.view/string.view.ops/subview.pass.cpp | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 8d714fff8cd3b..09ff13f98b009 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -13,7 +13,9 @@
// constexpr basic_string_view<_CharT, _Traits> subview(size_type __pos = 0, size_type __n = npos) const;
#include <cassert>
+#include <concepts>
#include <string>
+#include <string_view>
#include <utility>
#include "constexpr_char_traits.h"
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
index 57947bd0e9ecd..ee083a8d432ac 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
@@ -14,7 +14,8 @@
// size_type n = npos) const; // freestanding-deleted
#include <cassert>
-#include <string>
+#include <concepts>
+#include <string_view>
#include <utility>
#include "constexpr_char_traits.h"
>From fb19c8ab81594097d2cbabd592102540af867a8a Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 18:54:30 +0300
Subject: [PATCH 10/13] Updated implementation and tests
---
libcxx/include/string_view | 7 +++++--
.../string.ops/string_substr/subview.pass.cpp | 18 +++++++++++------
.../string.view.ops/subview.pass.cpp | 20 ++++++++++++-------
3 files changed, 30 insertions(+), 15 deletions(-)
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index 952d44123622b..7b093813b52c5 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -469,8 +469,11 @@ public:
# if _LIBCPP_STD_VER >= 26
_LIBCPP_HIDE_FROM_ABI constexpr basic_string_view subview(size_type __pos = 0, size_type __n = npos) const {
- return this->substr(__pos, __n);
- }
+ // Use the `__assume_valid` form of the constructor to avoid an unnecessary check. Any substring of a view is a
+ // valid view. In particular, `size()` is known to be smaller than `numeric_limits<difference_type>::max()`, so the
+ // new size is also smaller. See also https://github.com/llvm/llvm-project/issues/91634.
+ return __pos > size() ? (__throw_out_of_range("string_view::subview"), basic_string_view())
+ : basic_string_view(__assume_valid(), data() + __pos, std::min(__n, size() - __pos)); }
# endif
_LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
index 09ff13f98b009..7b9b0df9aad32 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/subview.pass.cpp
@@ -62,8 +62,10 @@ constexpr void test() {
try {
s.subview(s.size() + 1);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
@@ -71,8 +73,10 @@ constexpr void test() {
try {
s.subview(s.size() + 1, 0);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
@@ -80,8 +84,10 @@ constexpr void test() {
try {
s.subview(s.size() + 1, 1);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
}
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
index ee083a8d432ac..a4d0467738041 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
@@ -60,8 +60,10 @@ constexpr void test() {
try {
sv.subview(sv.size() + 1);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
@@ -69,8 +71,10 @@ constexpr void test() {
try {
sv.subview(sv.size() + 1, 0);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
@@ -78,8 +82,10 @@ constexpr void test() {
try {
sv.subview(sv.size() + 1, 1);
assert(false && "Expected std::out_of_range exception");
- } catch (const std::out_of_range&) {
- // Expected exception...
+ } catch ([[maybe_unused]] const std::out_of_range& ex) {
+ LIBCPP_ASSERT(std::string(ex.what()) == "string_view::subview");
+ } catch (...) {
+ assert(false && "Expected std::out_of_range exception");
}
}
}
@@ -115,7 +121,7 @@ constexpr bool test() {
int main(int, char**) {
test();
- static_assert(test());
+ // static_assert(test());
return 0;
}
>From 5f64a5ae872f48331906a9fec66364d81e97d895 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hristo.goshev.hristov at gmail.com>
Date: Wed, 6 Aug 2025 18:58:54 +0300
Subject: [PATCH 11/13] Update
libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
---
.../std/strings/string.view/string.view.ops/subview.pass.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
index a4d0467738041..b135cce7aa2c4 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/subview.pass.cpp
@@ -121,7 +121,7 @@ constexpr bool test() {
int main(int, char**) {
test();
- // static_assert(test());
+ static_assert(test());
return 0;
}
>From d3eeeb46484466342aa5588ae03ee13b4aae99eb Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 19:11:32 +0300
Subject: [PATCH 12/13] Update some more
---
libcxx/include/string_view | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index 7b093813b52c5..e38a7ce7c6a73 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -459,21 +459,23 @@ public:
return __rlen;
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view substr(size_type __pos = 0, size_type __n = npos) const {
+ _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI inline basic_string_view
+ __subview(size_type __pos, size_type __n, const char* __msg) const {
// Use the `__assume_valid` form of the constructor to avoid an unnecessary check. Any substring of a view is a
// valid view. In particular, `size()` is known to be smaller than `numeric_limits<difference_type>::max()`, so the
// new size is also smaller. See also https://github.com/llvm/llvm-project/issues/91634.
- return __pos > size() ? (__throw_out_of_range("string_view::substr"), basic_string_view())
+ return __pos > size() ? (__throw_out_of_range(__msg), basic_string_view())
: basic_string_view(__assume_valid(), data() + __pos, std::min(__n, size() - __pos));
}
+ _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view substr(size_type __pos = 0, size_type __n = npos) const {
+ return __subview(__pos, __n, "string_view::substr");
+ }
+
# if _LIBCPP_STD_VER >= 26
_LIBCPP_HIDE_FROM_ABI constexpr basic_string_view subview(size_type __pos = 0, size_type __n = npos) const {
- // Use the `__assume_valid` form of the constructor to avoid an unnecessary check. Any substring of a view is a
- // valid view. In particular, `size()` is known to be smaller than `numeric_limits<difference_type>::max()`, so the
- // new size is also smaller. See also https://github.com/llvm/llvm-project/issues/91634.
- return __pos > size() ? (__throw_out_of_range("string_view::subview"), basic_string_view())
- : basic_string_view(__assume_valid(), data() + __pos, std::min(__n, size() - __pos)); }
+ return __subview(__pos, __n, "string_view::subview");
+ }
# endif
_LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
>From 292cb6c9f3409926b0be99609f0096bfa222e019 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Wed, 6 Aug 2025 19:36:58 +0300
Subject: [PATCH 13/13] Fixed `<version>`
---
libcxx/docs/FeatureTestMacroTable.rst | 4 ++--
libcxx/include/version | 2 +-
.../string.version.compile.pass.cpp | 15 ++++++---------
.../string_view.version.compile.pass.cpp | 15 ++++++---------
.../version.version.compile.pass.cpp | 15 ++++++---------
.../generate_feature_test_macro_components.py | 2 +-
6 files changed, 22 insertions(+), 31 deletions(-)
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 1e88c6c0bec47..0008232ae91d5 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -404,8 +404,6 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_string_resize_and_overwrite`` ``202110L``
---------------------------------------------------------- -----------------
- ``__cpp_lib_string_subview`` ``202506L``
- ---------------------------------------------------------- -----------------
``__cpp_lib_to_underlying`` ``202102L``
---------------------------------------------------------- -----------------
``__cpp_lib_tuple_like`` *unimplemented*
@@ -508,6 +506,8 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_sstream_from_string_view`` ``202306L``
---------------------------------------------------------- -----------------
+ ``__cpp_lib_string_subview`` ``202506L``
+ ---------------------------------------------------------- -----------------
``__cpp_lib_string_view`` ``202403L``
---------------------------------------------------------- -----------------
``__cpp_lib_submdspan`` *unimplemented*
diff --git a/libcxx/include/version b/libcxx/include/version
index 8c5defa3ed8a9..f2fb9aef923ee 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -536,7 +536,6 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_stdatomic_h 202011L
# define __cpp_lib_string_contains 202011L
# define __cpp_lib_string_resize_and_overwrite 202110L
-# define __cpp_lib_string_subview 202506L
# define __cpp_lib_to_underlying 202102L
// # define __cpp_lib_tuple_like 202207L
# define __cpp_lib_unreachable 202202L
@@ -601,6 +600,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_span_at 202311L
# define __cpp_lib_span_initializer_list 202311L
# define __cpp_lib_sstream_from_string_view 202306L
+# define __cpp_lib_string_subview 202506L
# undef __cpp_lib_string_view
# define __cpp_lib_string_view 202403L
// # define __cpp_lib_submdspan 202306L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
index c69c8ed59fb61..147854eead2cc 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp
@@ -61,7 +61,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifdef __cpp_lib_string_udls
@@ -119,7 +119,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -186,7 +186,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -274,7 +274,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -370,11 +370,8 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++23"
# endif
-# ifndef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should be defined in c++23"
-# endif
-# if __cpp_lib_string_subview != 202506L
-# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
index ed13f392b1b7f..2c3716111102a 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp
@@ -41,7 +41,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifdef __cpp_lib_string_view
@@ -71,7 +71,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifdef __cpp_lib_string_view
@@ -101,7 +101,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_view
@@ -149,7 +149,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_view
@@ -199,11 +199,8 @@
# error "__cpp_lib_string_contains should have the value 202011L in c++23"
# endif
-# ifndef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should be defined in c++23"
-# endif
-# if __cpp_lib_string_subview != 202506L
-# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_view
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index 15048bb2b3253..3c21ed92cfc49 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -821,7 +821,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifdef __cpp_lib_string_udls
@@ -1780,7 +1780,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -2925,7 +2925,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -4343,7 +4343,7 @@
# endif
# ifdef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should not be defined before c++23"
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
@@ -5994,11 +5994,8 @@
# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++23"
# endif
-# ifndef __cpp_lib_string_subview
-# error "__cpp_lib_string_subview should be defined in c++23"
-# endif
-# if __cpp_lib_string_subview != 202506L
-# error "__cpp_lib_string_subview should have the value 202506L in c++23"
+# ifdef __cpp_lib_string_subview
+# error "__cpp_lib_string_subview should not be defined before c++26"
# endif
# ifndef __cpp_lib_string_udls
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 6403743d20b7e..2c0c304d5c2f4 100644
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1337,7 +1337,7 @@ def add_version_header(tc):
},
{
"name": "__cpp_lib_string_subview",
- "values": {"c++23": 202506},
+ "values": {"c++26": 202506},
"headers": ["string", "string_view"],
},
{
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