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Define std::ssize for C++20 (P1227R2)

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* include/bits/range_access.h (ssize): Define for C++20.
	* testsuite/24_iterators/range_access_cpp20.cc: New test.
	* doc/xml/manual/status_cxx2020.xml: Update P1227R2 status.
	* doc/html/*: Regenerate.

From-SVN: r275458
This commit is contained in:
Jonathan Wakely 2019-09-06 13:54:51 +01:00 • committed by Jonathan Wakely
parent 400b8274e6
commit 4ef5bbd815
5 changed files with 92 additions and 4 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,3 +1,10 @@
2019-09-06 Jonathan Wakely <jwakely@redhat.com>
* include/bits/range_access.h (ssize): Define for C++20.
* testsuite/24_iterators/range_access_cpp20.cc: New test.
* doc/xml/manual/status_cxx2020.xml: Update P1227R2 status.
* doc/html/*: Regenerate.
2019-09-06 Florian Weimer <fweimer@redhat.com>
* configure: Regenerate.

4
libstdc++-v3/doc/html/manual/status.html
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@ -1422,11 +1422,11 @@ Feature-testing recommendations for C++</a>.
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1001r2.html" target="_top">
P1001R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Signed ssize() functions, unsigned size() functions </td><td align="left">
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Signed ssize() functions, unsigned size() functions </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1227r2.html" target="_top">
P1227R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Ranges Design Cleanup </td><td align="left">
</td><td align="center"> 10.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Ranges Design Cleanup </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1252r2.pdf" target="_top">
P1252R2
</a>

3
libstdc++-v3/doc/xml/manual/status_cxx2020.xml
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@ -1086,14 +1086,13 @@ Feature-testing recommendations for C++</link>.
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Signed ssize() functions, unsigned size() functions </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1227r2.html">
P1227R2
</link>
</entry>
<entry align="center"> </entry>
<entry align="center"> 10.1 </entry>
<entry />
</row>

15
libstdc++-v3/include/bits/range_access.h
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@ -319,6 +319,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif // C++17
#if __cplusplus > 201703L
template<typename _Container>
constexpr auto
ssize(const _Container& __cont)
noexcept(noexcept(__cont.size()))
-> common_type_t<ptrdiff_t, make_signed_t<decltype(__cont.size())>>
{
using type = make_signed_t<decltype(__cont.size())>;
return static_cast<common_type_t<ptrdiff_t, type>>(__cont.size());
}
template<typename _Tp, ptrdiff_t _Num>
constexpr ptrdiff_t
ssize(const _Tp (&)[_Num]) noexcept
{ return _Num; }
// "why are these in namespace std:: and not __gnu_cxx:: ?"
// because if we don't put them here it's impossible to
// have implicit ADL with "using std::begin/end/size/data;".

67
libstdc++-v3/testsuite/24_iterators/range_access_cpp20.cc Normal file
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@ -0,0 +1,67 @@
// { dg-options "-std=gnu++2a" }
// { dg-do compile { target c++2a } }
// Copyright (C) 2019 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/>.
// N4830 23.7, Range access [iterator.range]
#include <iterator>
void
test01()
{
static int i[1];
constexpr auto s = std::ssize(i);
const std::ptrdiff_t* check_type = &s;
static_assert(s == 1);
}
void
test02()
{
static int i[] = { 1, 2 };
constexpr auto s = std::ssize(i);
const std::ptrdiff_t* check_type = &s;
static_assert(s == 2);
}
void
test03()
{
struct Cont
{
constexpr unsigned short size() const { return 3; }
};
constexpr Cont c;
constexpr auto s = std::ssize(c);
const std::ptrdiff_t* check_type = &s;
static_assert(s == 3);
}
void
test04()
{
struct Cont
{
constexpr unsigned long long size() const { return 4; }
};
constexpr Cont c;
constexpr auto s = std::ssize(c);
const long long* check_type = &s;
static_assert(s == 4);
}