* [PATCH] Define std::ssize for C++20 (P1227R2)
@ 2019-09-06 12:54 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2019-09-06 12:54 UTC (permalink / raw)
To: libstdc++, gcc-patches
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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.
Tested x86_64-linux, committed to trunk.
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commit 606b6138a44f1f31577f480f37a3d263dd2bfc65
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Fri Sep 6 13:31:15 2019 +0100
Define std::ssize for C++20 (P1227R2)
* 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.
diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2020.xml b/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
index ffd73aefc96..fa0c89dd346 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
@@ -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>
diff --git a/libstdc++-v3/include/bits/range_access.h b/libstdc++-v3/include/bits/range_access.h
index 44b9c6c3596..c5744145590 100644
--- a/libstdc++-v3/include/bits/range_access.h
+++ b/libstdc++-v3/include/bits/range_access.h
@@ -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;".
diff --git a/libstdc++-v3/testsuite/24_iterators/range_access_cpp20.cc b/libstdc++-v3/testsuite/24_iterators/range_access_cpp20.cc
new file mode 100644
index 00000000000..567b0564507
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/range_access_cpp20.cc
@@ -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);
+}
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