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* [gcc r14-8740] libstdc++: Allow explicit conversion of string views with different traits
@ 2024-02-02 10:24 Jonathan Wakely
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From: Jonathan Wakely @ 2024-02-02 10:24 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:f60d7e1c64518936797ec1009cb49f72f8fe45b9
commit r14-8740-gf60d7e1c64518936797ec1009cb49f72f8fe45b9
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Feb 1 21:40:33 2024 +0000
libstdc++: Allow explicit conversion of string views with different traits
This was changed by LWG 3857.
libstdc++-v3/ChangeLog:
* include/std/string_view (basic_string_view(R&&)): Remove
constraint that traits_type must be the same, as per LWG 3857.
* testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc:
Explicit conversion between different specializations should be
allowed.
* testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc:
Likewise.
Diff:
---
libstdc++-v3/include/std/string_view | 2 --
.../basic_string_view/cons/char/range_c++20.cc | 21 ++++-----------------
.../basic_string_view/cons/wchar_t/range_c++20.cc | 21 ++++-----------------
3 files changed, 8 insertions(+), 36 deletions(-)
diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view
index b444b5b9a39b..e30a9c1768e0 100644
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -167,8 +167,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
&& (!requires (_DRange& __d) {
__d.operator ::std::basic_string_view<_CharT, _Traits>();
})
- && (!requires { typename _DRange::traits_type; }
- || is_same_v<typename _DRange::traits_type, _Traits>)
constexpr explicit
basic_string_view(_Range&& __r)
noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc
index 5d0396563fd8..bae8da1d2645 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc
@@ -115,23 +115,10 @@ test02()
static_assert( ! std::is_constructible_v<std::string_view, V1> );
using V2 = std::basic_string_view<char, __gnu_cxx::char_traits<char>>;
- // V2::traits_type is not the right type
- static_assert( ! std::is_constructible_v<std::string_view, V2> );
-
- struct V3 : V2
- {
- private:
- using V2::traits_type;
- };
- // V3::traits_type is not a valid (accessible) type
- static_assert( std::is_constructible_v<std::string_view, V3> );
-
- struct V4 : V2
- {
- using traits_type = std::string_view::traits_type;
- };
- // V4::traits_type is the right type
- static_assert( std::is_constructible_v<std::string_view, V4> );
+ // LWG 3857
+ // basic_string_view should allow explicit conversion when only traits vary
+ static_assert( std::is_constructible_v<std::string_view, V2> );
+ static_assert( ! std::is_convertible_v<V2, std::string_view> );
}
void
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc
index d6996a1dd6f0..3cf154d8602d 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc
@@ -115,23 +115,10 @@ test02()
static_assert( ! std::is_constructible_v<std::wstring_view, V1> );
using V2 = std::basic_string_view<wchar_t, __gnu_cxx::char_traits<wchar_t>>;
- // V2::traits_type is not the right type
- static_assert( ! std::is_constructible_v<std::wstring_view, V2> );
-
- struct V3 : V2
- {
- private:
- using V2::traits_type;
- };
- // V3::traits_type is not a valid (accessible) type
- static_assert( std::is_constructible_v<std::wstring_view, V3> );
-
- struct V4 : V2
- {
- using traits_type = std::wstring_view::traits_type;
- };
- // V4::traits_type is the right type
- static_assert( std::is_constructible_v<std::wstring_view, V4> );
+ // LWG 3857
+ // basic_string_view should allow explicit conversion when only traits vary
+ static_assert( std::is_constructible_v<std::wstring_view, V2> );
+ static_assert( ! std::is_convertible_v<V2, std::wstring_view> );
}
void
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