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P0887R1 The identity metafunction

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* include/std/type_traits (type_identity, type_identity_t): Define
        for C++2a.
	* testsuite/20_util/type_identity/requirements/alias_decl.cc: New.
	* testsuite/20_util/type_identity/requirements/
	explicit_instantiation.cc:New.
	* testsuite/20_util/type_identity/requirements/typedefs.cc: New.

From-SVN: r262319
This commit is contained in:
Jonathan Wakely 2018-07-02 22:05:08 +01:00 committed by Jonathan Wakely
parent e112d53aca
commit ee896276f6
5 changed files with 173 additions and 0 deletions
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8
libstdc++-v3/ChangeLog
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@ -1,5 +1,13 @@
2018-07-02 Jonathan Wakely <jwakely@redhat.com>
P0887R1 The identity metafunction
* include/std/type_traits (type_identity, type_identity_t): Define
for C++2a.
* testsuite/20_util/type_identity/requirements/alias_decl.cc: New.
* testsuite/20_util/type_identity/requirements/
explicit_instantiation.cc:New.
* testsuite/20_util/type_identity/requirements/typedefs.cc: New.
* include/bits/regex.h (sub_match::operator string_type): Call str().
(sub_match::compare): Use _M_str() instead of str().
(sub_match::_M_compare): New public function.

7
libstdc++-v3/include/std/type_traits
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@ -2996,6 +2996,13 @@ template <typename _From, typename _To>
template<typename _Tp>
using remove_cvref_t = __remove_cvref_t<_Tp>;
/// Identity metafunction.
template<typename _Tp>
struct type_identity { using type = _Tp; };
template<typename _Tp>
using type_identity_t = typename type_identity<_Tp>::type;
#endif // C++2a
_GLIBCXX_END_NAMESPACE_VERSION

35
libstdc++-v3/testsuite/20_util/type_identity/requirements/alias_decl.cc Normal file
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@ -0,0 +1,35 @@
// Copyright (C) 2018 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++2a" }
// { dg-do compile { target c++2a } }
//
#include <type_traits>
using namespace std;
template<typename T, typename = std::type_identity_t<T>>
struct test; // undefined
template<typename T>
struct test<T, T> : std::true_type { };
static_assert( test<const int>{}, "type_identity_t<const int>" );
static_assert( test<volatile int>{}, "type_identity_t<volatile int>" );
static_assert( test<unsigned>{}, "type_identity_t<unsigned>" );
static_assert( test<char>{}, "type_identity_t<char>" );
static_assert( test<signed char>{}, "type_identity_t<signed char>" );

29
libstdc++-v3/testsuite/20_util/type_identity/requirements/explicit_instantiation.cc Normal file
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// Copyright (C) 2018 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++2a" }
// { dg-do compile { target c++2a } }
// NB: This file is for testing type_traits with NO OTHER INCLUDES.
#include <type_traits>
namespace std
{
typedef short test_type;
template struct type_identity<test_type>;
}

94
libstdc++-v3/testsuite/20_util/type_identity/requirements/typedefs.cc Normal file
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@ -0,0 +1,94 @@
// Copyright (C) 2018 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++2a" }
// { dg-do compile { target c++2a } }
#include <type_traits>
template<typename T, typename = typename std::type_identity<T>::type>
struct test; // undefined
template<typename T>
struct test<T, T> : std::true_type { };
enum test_enum { };
struct test_class { };
struct incomplete_class;
void test01()
{
static_assert(test<float>::value, "");
static_assert(test<const unsigned int>::value, "");
static_assert(test<const unsigned int>::value, "");
static_assert(test<volatile unsigned int>::value, "");
static_assert(test<const volatile unsigned int>::value, "");
static_assert(test<const unsigned char>::value, "");
#ifdef _GLIBCXX_USE_WCHAR_T
static_assert(test<volatile wchar_t>::value, "" );
#endif
// Pointers
static_assert(test<void*>::value, "");
static_assert(test<long*>::value, "");
// References
static_assert(test<short&>::value, "");
static_assert(test<char&&>::value, "");
static_assert(test<int*&>::value, "");
// Arrays
static_assert(test<int[]>::value, "");
static_assert(test<int[2]>::value, "");
static_assert(test<int[2][3]>::value, "");
static_assert(test<int(*)[2]>::value, "");
static_assert(test<int(&)[2]>::value, "");
static_assert(test<test_enum>::value, "");
static_assert(test<test_class>::value, "");
static_assert(test<incomplete_class>::value, "");
// Functions
static_assert(test<void(*)()>::value, "");
static_assert(test<int(*)(int) noexcept>::value, "");
static_assert(test<void(&)()>::value, "");
static_assert(test<long(&)(long) noexcept>::value, "");
static_assert(test<void()>::value, "");
static_assert(test<int(int, int)>::value, "");
static_assert(test<void() noexcept>::value, "");
static_assert(test<int(int, int) noexcept>::value, "");
// Abominable function types
static_assert(test<void(int) const>::value, "");
static_assert(test<void(int) const volatile>::value, "");
// Pointers to members
static_assert(test<int incomplete_class::*>::value, "");
static_assert(test<void(incomplete_class::*)(int)>::value, "");
static_assert(test<void(incomplete_class::*)(int) noexcept>::value, "");
static_assert(test<void(incomplete_class::*)() const>::value, "");
static_assert(test<void(incomplete_class::*)() &>::value, "");
static_assert(test<void(incomplete_class::*)() &&>::value, "");
static_assert(test<void(incomplete_class::*)() volatile &&>::value, "");
#ifndef __STRICT_ANSI__
// GNU Extensions.
#ifdef _GLIBCXX_USE_INT128
static_assert(test<unsigned __int128>::value, "");
static_assert(test<unsigned __int128>::value, "");
#endif
#endif
}