+2017-06-07 Jonathan Wakely <jwakely@redhat.com>
+
+ * include/bits/alloc_traits.h (__is_allocator, _RequireAllocator):
+ New trait and alias for detecting Allocator-like types.
+ * include/bits/basic_string.h (basic_string): Add deduction guide
+ from P0433.
+ * include/ext/alloc_traits.h (__gnu_cxx::__alloc_traits): Add template
+ parameter with default template argument that causes substitution
+ failures for types that cannot be allocators.
+ * testsuite/21_strings/basic_string/cons/char/deduction.cc: New.
+ * testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc: New.
+
2017-06-02 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/80939
: is_copy_constructible<_Tp>
{ };
+#if __cplusplus >= 201103L
+ // Trait to detect Allocator-like types.
+ template<typename _Alloc, typename = void>
+ struct __is_allocator : false_type { };
+
+ template<typename _Alloc>
+ struct __is_allocator<_Alloc,
+ __void_t<typename _Alloc::value_type,
+ decltype(std::declval<_Alloc&>().allocate(size_t{}))>>
+ : true_type { };
+
+ template<typename _Alloc>
+ using _RequireAllocator
+ = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;
+#endif
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
};
#endif // !_GLIBCXX_USE_CXX11_ABI
+#if __cpp_deduction_guides >= 201606
+_GLIBCXX_BEGIN_NAMESPACE_CXX11
+ template<typename _InputIterator, typename _CharT
+ = typename iterator_traits<_InputIterator>::value_type,
+ typename _Allocator = allocator<_CharT>,
+ typename = _RequireInputIter<_InputIterator>,
+ typename = _RequireAllocator<_Allocator>>
+ basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
+ -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
+_GLIBCXX_END_NAMESPACE_CXX11
+#endif
+
// operator+
/**
* @brief Concatenate two strings.
* @brief Uniform interface to C++98 and C++11 allocators.
* @ingroup allocators
*/
-template<typename _Alloc>
+template<typename _Alloc, typename = typename _Alloc::value_type>
struct __alloc_traits
#if __cplusplus >= 201103L
: std::allocator_traits<_Alloc>
--- /dev/null
+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++1z } }
+
+#include <string>
+#include <testsuite_iterators.h>
+
+template<typename C>
+ using input_iterator_seq
+ = __gnu_test::test_container<C, __gnu_test::input_iterator_wrapper>;
+
+template<typename T, typename U> struct require_same;
+template<typename T> struct require_same<T, T> { using type = void; };
+
+template<typename T, typename U>
+ typename require_same<T, U>::type
+ check_type(U&) { }
+
+void
+test01()
+{
+ std::string s0;
+ std::allocator<char> a;
+
+ std::basic_string s1 = s0;
+ check_type<std::string>(s1);
+
+ std::basic_string s2 = std::move(s0);
+ check_type<std::string>(s2);
+
+ const std::basic_string s3 = s0;
+ check_type<const std::string>(s3);
+
+ const std::basic_string s4 = s3;
+ check_type<const std::string>(s4);
+
+ std::basic_string s5(s0, a);
+ check_type<std::string>(s5);
+
+ std::basic_string s6(std::move(s0), a);
+ check_type<std::string>(s6);
+
+ std::basic_string s7(s0, 0, 0);
+ check_type<std::string>(s7);
+}
+
+void
+test02()
+{
+ char a[1] = {};
+ input_iterator_seq<char> seq(a);
+
+ std::basic_string s1(seq.begin(), seq.end());
+ check_type<std::string>(s1);
+
+ std::basic_string s2(seq.begin(), seq.end(), std::allocator<char>());
+ check_type<std::string>(s2);
+
+ std::basic_string s3((char)1, 'a');
+ check_type<std::string>(s3);
+
+ std::basic_string s4((char)1, 'a', std::allocator<char>());
+ check_type<std::string>(s4);
+}
+
+void
+test03()
+{
+ char16_t a[1] = {};
+ input_iterator_seq<char16_t> seq(a);
+
+ std::basic_string s1(seq.begin(), seq.end());
+ check_type<std::u16string>(s1);
+
+ std::basic_string s2(seq.begin(), seq.end(), std::allocator<char16_t>());
+ check_type<std::u16string>(s2);
+
+ std::basic_string s3((char16_t)1, u'a');
+ check_type<std::u16string>(s3);
+
+ std::basic_string s4((char16_t)1, u'a', std::allocator<char16_t>());
+ check_type<std::u16string>(s4);
+}
+
+void
+test04()
+{
+ char32_t a[1] = {};
+ input_iterator_seq<char32_t> seq(a);
+
+ std::basic_string s1(seq.begin(), seq.end());
+ check_type<std::u32string>(s1);
+
+ std::basic_string s2(seq.begin(), seq.end(), std::allocator<char32_t>());
+ check_type<std::u32string>(s2);
+
+ std::basic_string s3((char32_t)1, U'a');
+ check_type<std::u32string>(s3);
+
+ std::basic_string s4((char32_t)1, U'a', std::allocator<char32_t>());
+ check_type<std::u32string>(s4);
+}
--- /dev/null
+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++1z } }
+
+#include <string>
+#include <testsuite_iterators.h>
+
+template<typename T, typename U> struct require_same;
+template<typename T> struct require_same<T, T> { using type = void; };
+
+template<typename T, typename U>
+ typename require_same<T, U>::type
+ check_type(U&) { }
+
+void
+test01()
+{
+ std::wstring s0;
+ std::allocator<wchar_t> a;
+
+ std::basic_string s1 = s0;
+ check_type<std::wstring>(s1);
+
+ std::basic_string s2 = std::move(s0);
+ check_type<std::wstring>(s2);
+
+ const std::basic_string s3 = s0;
+ check_type<const std::wstring>(s3);
+
+ const std::basic_string s4 = s2;
+ check_type<const std::wstring>(s4);
+
+ std::basic_string s5(s0, a);
+ check_type<std::wstring>(s5);
+
+ std::basic_string s6(std::move(s0), a);
+ check_type<std::wstring>(s6);
+
+ std::basic_string s7(s0, 0, 0);
+ check_type<std::wstring>(s7);
+}
+
+void
+test02()
+{
+ using namespace __gnu_test;
+ wchar_t a[1] = {};
+ test_container<wchar_t, input_iterator_wrapper> seq(a);
+
+ std::basic_string s1(seq.begin(), seq.end());
+ check_type<std::wstring>(s1);
+
+ std::basic_string s2(seq.begin(), seq.end(), std::allocator<wchar_t>());
+ check_type<std::wstring>(s2);
+
+ std::basic_string s3((wchar_t)1, L'a');
+ check_type<std::wstring>(s3);
+
+ std::basic_string s4((wchar_t)1, L'a', std::allocator<wchar_t>());
+ check_type<std::wstring>(s4);
+}
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