libstdc++: Make string_view::copy usable in constant expressions (PR 94498)
PR libstdc++/94498 * include/bits/char_traits.h (__gnu_cxx::char_traits::move): Make it usable in constant expressions for C++20. (__gnu_cxx::char_traits::copy, __gnu_cxx::char_traits::assign): Add _GLIBCXX20_CONSTEXPR. (std::char_traits<char>, std::char_traits<wchar_t>) (std::char_traits<char8_t>): Make move, copy and assign usable in constant expressions for C++20. (std::char_traits<char16_t>, std::char_traits<char32_t>): Make move and copy usable in constant expressions for C++20. * include/std/string_view (basic_string_view::copy): Add _GLIBCXX20_CONSTEXPR. * testsuite/21_strings/basic_string_view/operations/copy/char/ constexpr.cc: New test. * testsuite/21_strings/basic_string_view/operations/copy/wchar_t/ constexpr.cc: New test.
This commit is contained in:
Jonathan Wakely
parent
f84aded848
commit
b696698767
5 changed files with 167 additions and 18 deletions
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@ -1,3 +1,22 @@
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2020-04-06 Jonathan Wakely <jwakely@redhat.com>
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PR libstdc++/94498
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* include/bits/char_traits.h (__gnu_cxx::char_traits::move): Make it
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usable in constant expressions for C++20.
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(__gnu_cxx::char_traits::copy, __gnu_cxx::char_traits::assign): Add
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_GLIBCXX20_CONSTEXPR.
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(std::char_traits<char>, std::char_traits<wchar_t>)
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(std::char_traits<char8_t>): Make move, copy and assign usable in
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constant expressions for C++20.
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(std::char_traits<char16_t>, std::char_traits<char32_t>): Make move
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and copy usable in constant expressions for C++20.
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* include/std/string_view (basic_string_view::copy): Add
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_GLIBCXX20_CONSTEXPR.
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* testsuite/21_strings/basic_string_view/operations/copy/char/
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constexpr.cc: New test.
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* testsuite/21_strings/basic_string_view/operations/copy/wchar_t/
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constexpr.cc: New test.
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2020-04-05 Gerald Pfeifer <gerald@pfeifer.com>
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* doc/xml/manual/appendix_contributing.xml: Refer to Git
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@ -113,13 +113,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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static _GLIBCXX14_CONSTEXPR const char_type*
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find(const char_type* __s, std::size_t __n, const char_type& __a);
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, std::size_t __n);
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, std::size_t __n);
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, std::size_t __n, char_type __a);
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static _GLIBCXX_CONSTEXPR char_type
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@ -179,17 +179,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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template<typename _CharT>
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_GLIBCXX20_CONSTEXPR
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typename char_traits<_CharT>::char_type*
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char_traits<_CharT>::
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move(char_type* __s1, const char_type* __s2, std::size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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{
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if (__s1 > __s2 && __s1 < __s2 + __n)
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std::copy_backward(__s2, __s2 + __n, __s1);
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else
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std::copy(__s2, __s2 + __n, __s1);
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return __s1;
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}
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#endif
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return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
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__n * sizeof(char_type)));
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}
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template<typename _CharT>
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_GLIBCXX20_CONSTEXPR
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typename char_traits<_CharT>::char_type*
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char_traits<_CharT>::
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copy(char_type* __s1, const char_type* __s2, std::size_t __n)
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@ -200,6 +212,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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template<typename _CharT>
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_GLIBCXX20_CONSTEXPR
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typename char_traits<_CharT>::char_type*
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char_traits<_CharT>::
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assign(char_type* __s, std::size_t __n, char_type __a)
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@ -349,27 +362,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
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#endif
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return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
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#endif
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return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, size_t __n, char_type __a)
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{
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if (__n == 0)
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return __s;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
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#endif
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return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
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}
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@ -458,27 +483,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return wmemchr(__s, __a, __n);
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
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#endif
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return wmemmove(__s1, __s2, __n);
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
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#endif
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return wmemcpy(__s1, __s2, __n);
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, size_t __n, char_type __a)
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{
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if (__n == 0)
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return __s;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
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#endif
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return wmemset(__s, __a, __n);
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}
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@ -567,27 +604,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
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#endif
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return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
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#endif
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return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, size_t __n, char_type __a)
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{
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if (__n == 0)
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return __s;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
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#endif
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return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
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}
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return 0;
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
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#endif
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return (static_cast<char_type*>
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(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
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#endif
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return (static_cast<char_type*>
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(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, size_t __n, char_type __a)
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{
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for (size_t __i = 0; __i < __n; ++__i)
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@ -783,25 +840,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return 0;
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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move(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
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#endif
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return (static_cast<char_type*>
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(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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copy(char_type* __s1, const char_type* __s2, size_t __n)
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{
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if (__n == 0)
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return __s1;
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#ifdef __cpp_lib_is_constant_evaluated
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if (std::is_constant_evaluated())
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return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
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#endif
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return (static_cast<char_type*>
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(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
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}
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static char_type*
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static _GLIBCXX20_CONSTEXPR char_type*
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assign(char_type* __s, size_t __n, char_type __a)
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{
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for (size_t __i = 0; __i < __n; ++__i)
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// [string.view.ops], string operations:
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_GLIBCXX20_CONSTEXPR
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size_type
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copy(_CharT* __str, size_type __n, size_type __pos = 0) const
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{
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// Copyright (C) 2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-options "-std=gnu++2a" }
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// { dg-do compile { target c++2a } }
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#include <string_view>
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constexpr bool
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test01()
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{
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std::string_view s = "Everything changes and nothing stands still.";
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char buf[7];
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auto n = s.copy(buf, 7, 11);
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return std::string_view(buf, n) == "changes";
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}
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static_assert( test01() );
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// Copyright (C) 2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-options "-std=gnu++2a" }
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// { dg-do compile { target c++2a } }
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#include <string_view>
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constexpr bool
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test01()
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{
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std::wstring_view s = L"Everything changes and nothing stands still.";
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wchar_t buf[7];
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auto n = s.copy(buf, 7, 11);
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return std::wstring_view(buf, n) == L"changes";
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}
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static_assert( test01() );
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