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[libc++][strings] P2591R5: Concatenation of strings and string views (#88389)
Implemented: https://wg21.link/P2591R5 - https://eel.is/c++draft/string.syn - https://eel.is/c++draft/string.op.plus --------- Co-authored-by: Hristo Hristov <[email protected]>
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‎libcxx/docs/FeatureTestMacroTable.rst

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@@ -474,6 +474,8 @@ Status
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---------------------------------------------------------- -----------------
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``__cpp_lib_sstream_from_string_view`` ``202306L``
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---------------------------------------------------------- -----------------
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``__cpp_lib_string_view`` ``202403L``
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---------------------------------------------------------- -----------------
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``__cpp_lib_submdspan`` *unimplemented*
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---------------------------------------------------------- -----------------
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``__cpp_lib_text_encoding`` *unimplemented*

‎libcxx/docs/ReleaseNotes/19.rst

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@@ -46,6 +46,7 @@ Implemented Papers
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- P2872R3 - Remove ``wstring_convert`` From C++26
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- P3142R0 - Printing Blank Lines with ``println`` (as DR against C++23)
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- P2944R3 - Comparisons for ``reference_wrapper`` (comparison operators for ``reference_wrapper`` only)
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- P2591R5 - Concatenation of strings and string views
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- P2968R2 - Make ``std::ignore`` a first-class object
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- P2302R4 - ``std::ranges::contains``
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- P1659R3 - ``std::ranges::starts_with`` and ``std::ranges::ends_with``

‎libcxx/docs/Status/Cxx2cPapers.csv

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@@ -55,7 +55,7 @@
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"`P2845R8 <https://wg21.link/P2845R8>`__","LWG","Formatting of ``std::filesystem::path``","Tokyo March 2024","","","|format|"
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"`P0493R5 <https://wg21.link/P0493R5>`__","LWG","Atomic minimum/maximum","Tokyo March 2024","","",""
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"`P2542R8 <https://wg21.link/P2542R8>`__","LWG","``views::concat``","Tokyo March 2024","","","|ranges|"
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"`P2591R5 <https://wg21.link/P2591R5>`__","LWG","Concatenation of strings and string views","Tokyo March 2024","","",""
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"`P2591R5 <https://wg21.link/P2591R5>`__","LWG","Concatenation of strings and string views","Tokyo March 2024","|Complete|","19.0",""
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"`P2248R8 <https://wg21.link/P2248R8>`__","LWG","Enabling list-initialization for algorithms","Tokyo March 2024","","",""
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"`P2810R4 <https://wg21.link/P2810R4>`__","LWG","``is_debugger_present`` ``is_replaceable``","Tokyo March 2024","","",""
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"`P1068R11 <https://wg21.link/P1068R11>`__","LWG","Vector API for random number generation","Tokyo March 2024","","",""

‎libcxx/include/string

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@@ -407,6 +407,24 @@ template<class charT, class traits, class Allocator>
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basic_string<charT, traits, Allocator>
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operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs); // constexpr since C++20
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template<class charT, class traits, class Allocator>
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constexpr basic_string<charT, traits, Allocator>
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operator+(const basic_string<charT, traits, Allocator>& lhs,
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type_identity_t<basic_string_view<charT, traits>> rhs); // Since C++26
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template<class charT, class traits, class Allocator>
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constexpr basic_string<charT, traits, Allocator>
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operator+(basic_string<charT, traits, Allocator>&& lhs,
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type_identity_t<basic_string_view<charT, traits>> rhs); // Since C++26
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template<class charT, class traits, class Allocator>
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constexpr basic_string<charT, traits, Allocator>
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operator+(type_identity_t<basic_string_view<charT, traits>> lhs,
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const basic_string<charT, traits, Allocator>& rhs); // Since C++26
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template<class charT, class traits, class Allocator>
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constexpr basic_string<charT, traits, Allocator>
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operator+(type_identity_t<basic_string_view<charT, traits>> lhs,
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basic_string<charT, traits, Allocator>&& rhs); // Since C++26
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template<class charT, class traits, class Allocator>
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bool operator==(const basic_string<charT, traits, Allocator>& lhs,
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const basic_string<charT, traits, Allocator>& rhs) noexcept; // constexpr since C++20
@@ -687,6 +705,28 @@ template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
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operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
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#if _LIBCPP_STD_VER >= 26
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
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type_identity_t<basic_string_view<_CharT, _Traits>> __rhs);
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, type_identity_t<basic_string_view<_CharT, _Traits>> __rhs);
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
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const basic_string<_CharT, _Traits, _Allocator>& __rhs);
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs);
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#endif
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extern template _LIBCPP_EXPORTED_FROM_ABI string operator+
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<char, char_traits<char>, allocator<char> >(char const*, string const&);
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@@ -2150,6 +2190,10 @@ private:
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friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(value_type, const basic_string&);
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friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const basic_string&, const value_type*);
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friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const basic_string&, value_type);
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#if _LIBCPP_STD_VER >= 26
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friend constexpr basic_string operator+ <>(const basic_string&, type_identity_t<__self_view>);
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friend constexpr basic_string operator+ <>(type_identity_t<__self_view>, const basic_string&);
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#endif
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};
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// These declarations must appear before any functions are implicitly used
@@ -4007,6 +4051,60 @@ operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs) {
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#endif // _LIBCPP_CXX03_LANG
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#if _LIBCPP_STD_VER >= 26
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
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type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) {
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using _String = basic_string<_CharT, _Traits, _Allocator>;
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typename _String::size_type __lhs_sz = __lhs.size();
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typename _String::size_type __rhs_sz = __rhs.size();
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_String __r(__uninitialized_size_tag(),
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__lhs_sz + __rhs_sz,
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_String::__alloc_traits::select_on_container_copy_construction(__lhs.get_allocator()));
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auto __ptr = std::__to_address(__r.__get_pointer());
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_Traits::copy(__ptr, __lhs.data(), __lhs_sz);
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_Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
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_Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
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return __r;
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}
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs,
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type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) {
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__lhs.append(__rhs);
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return std::move(__lhs);
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}
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
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const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
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using _String = basic_string<_CharT, _Traits, _Allocator>;
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typename _String::size_type __lhs_sz = __lhs.size();
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typename _String::size_type __rhs_sz = __rhs.size();
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_String __r(__uninitialized_size_tag(),
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__lhs_sz + __rhs_sz,
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_String::__alloc_traits::select_on_container_copy_construction(__rhs.get_allocator()));
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auto __ptr = std::__to_address(__r.__get_pointer());
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_Traits::copy(__ptr, __lhs.data(), __lhs_sz);
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_Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
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_Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
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return __r;
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}
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template <class _CharT, class _Traits, class _Allocator>
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_LIBCPP_HIDE_FROM_ABI constexpr basic_string<_CharT, _Traits, _Allocator>
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operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
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basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
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__rhs.insert(0, __lhs);
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return std::move(__rhs);
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}
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#endif // _LIBCPP_STD_VER >= 26
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// swap
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template <class _CharT, class _Traits, class _Allocator>

‎libcxx/include/version

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@@ -231,7 +231,8 @@ __cpp_lib_stdatomic_h 202011L <stdatomic.h>
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__cpp_lib_string_contains 202011L <string> <string_view>
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__cpp_lib_string_resize_and_overwrite 202110L <string>
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__cpp_lib_string_udls 201304L <string>
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__cpp_lib_string_view 201803L <string> <string_view>
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__cpp_lib_string_view 202403L <string> <string_view>
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201803L // C++20
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201606L // C++17
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__cpp_lib_submdspan 202306L <mdspan>
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__cpp_lib_syncbuf 201803L <syncstream>
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# define __cpp_lib_span_at 202311L
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# define __cpp_lib_span_initializer_list 202311L
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# define __cpp_lib_sstream_from_string_view 202306L
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# undef __cpp_lib_string_view
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# define __cpp_lib_string_view 202403L
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// # define __cpp_lib_submdspan 202306L
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// # define __cpp_lib_text_encoding 202306L
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# undef __cpp_lib_to_chars

‎libcxx/test/std/language.support/support.limits/support.limits.general/string.version.compile.pass.cpp

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__cpp_lib_string_udls 201304L [C++14]
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__cpp_lib_string_view 201606L [C++17]
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201803L [C++20]
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202403L [C++26]
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__cpp_lib_to_string 202306L [C++26]
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*/
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# ifndef __cpp_lib_string_view
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# error "__cpp_lib_string_view should be defined in c++26"
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# endif
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# if __cpp_lib_string_view != 201803L
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# error "__cpp_lib_string_view should have the value 201803L in c++26"
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# if __cpp_lib_string_view != 202403L
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# error "__cpp_lib_string_view should have the value 202403L in c++26"
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# endif
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# if !defined(_LIBCPP_VERSION)

‎libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.compile.pass.cpp

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__cpp_lib_string_contains 202011L [C++23]
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__cpp_lib_string_view 201606L [C++17]
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201803L [C++20]
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202403L [C++26]
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*/
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#include <string_view>
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# ifndef __cpp_lib_string_view
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# error "__cpp_lib_string_view should be defined in c++26"
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# endif
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# if __cpp_lib_string_view != 201803L
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# error "__cpp_lib_string_view should have the value 201803L in c++26"
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# if __cpp_lib_string_view != 202403L
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# error "__cpp_lib_string_view should have the value 202403L in c++26"
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# endif
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#endif // TEST_STD_VER > 23

‎libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp

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__cpp_lib_string_udls 201304L [C++14]
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__cpp_lib_string_view 201606L [C++17]
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201803L [C++20]
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202403L [C++26]
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__cpp_lib_submdspan 202306L [C++26]
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__cpp_lib_syncbuf 201803L [C++20]
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__cpp_lib_text_encoding 202306L [C++26]
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# ifndef __cpp_lib_string_view
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# error "__cpp_lib_string_view should be defined in c++26"
78967897
# endif
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# if __cpp_lib_string_view != 201803L
7898-
# error "__cpp_lib_string_view should have the value 201803L in c++26"
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# if __cpp_lib_string_view != 202403L
7899+
# error "__cpp_lib_string_view should have the value 202403L in c++26"
78997900
# endif
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# if !defined(_LIBCPP_VERSION)

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