| Message ID | 20150827190516.GW2631@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Thu, 27 Aug 2015, Jonathan Wakely wrote: > The std::cbegin function in <bits/range_access.h> can't call the > std::begin function in <valarray> unless it knows about it, so we need > to declare the valarray overloads in <bits/range_access.h>. Hmm, do you remember why valarray has an ugly overload of std::begin instead of a nice member function begin like every other container ? It should at least be legal to implement it this way.
On 27/08/15 21:48 +0200, Marc Glisse wrote: >On Thu, 27 Aug 2015, Jonathan Wakely wrote: > >>The std::cbegin function in <bits/range_access.h> can't call the >>std::begin function in <valarray> unless it knows about it, so we need >>to declare the valarray overloads in <bits/range_access.h>. > >Hmm, do you remember why valarray has an ugly overload of std::begin >instead of a nice member function begin like every other container ? >It should at least be legal to implement it this way. No, sorry, I have no idea. C++11 added the begin non-members, and then C++14 added the cbegin non-member, which calls std::begin. I'm not convinced it's supposed to work with valarray, but it's confusing that it doesn't when std::begin(const valarray<T>&) exists.
On 2015/08/28 4:54, Jonathan Wakely wrote: > On 27/08/15 21:48 +0200, Marc Glisse wrote: >> On Thu, 27 Aug 2015, Jonathan Wakely wrote: >> >>> The std::cbegin function in <bits/range_access.h> can't call the >>> std::begin function in <valarray> unless it knows about it, so we need >>> to declare the valarray overloads in <bits/range_access.h>. >> >> Hmm, do you remember why valarray has an ugly overload of std::begin >> instead of a nice member function begin like every other container ? >> It should at least be legal to implement it this way. > > No, sorry, I have no idea. > > C++11 added the begin non-members, and then C++14 added the > cbegin non-member, which calls std::begin. > > I'm not convinced it's supposed to work with valarray, but it's > confusing that it doesn't when std::begin(const valarray<T>&) exists. > Likely this https://gcc.gnu.org/PR49022 .
commit bc5fced738a428c267ef1921f2e95514ffafd093
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Aug 27 18:44:59 2015 +0100
PR libstdc++/67374
* include/bits/range_access.h (valarray, begin, end): Declare.
* testsuite/26_numerics/valarray/range_access.cc: Test const
overloads.
* testsuite/26_numerics/valarray/range_access2.cc: New.
diff --git a/libstdc++-v3/include/bits/range_access.h b/libstdc++-v3/include/bits/range_access.h
index aa78afb..01a05bc 100644
--- a/libstdc++-v3/include/bits/range_access.h
+++ b/libstdc++-v3/include/bits/range_access.h
@@ -98,6 +98,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return __arr + _Nm; }
#if __cplusplus >= 201402L
+
+ template<typename _Tp> class valarray;
+ // These overloads must be declared for cbegin and cend to use them.
+ template<typename _Tp> _Tp* begin(valarray<_Tp>&);
+ template<typename _Tp> const _Tp* begin(const valarray<_Tp>&);
+ template<typename _Tp> _Tp* end(valarray<_Tp>&);
+ template<typename _Tp> const _Tp* end(const valarray<_Tp>&);
+
/**
* @brief Return an iterator pointing to the first element of
* the const container.
diff --git a/libstdc++-v3/testsuite/26_numerics/valarray/range_access.cc b/libstdc++-v3/testsuite/26_numerics/valarray/range_access.cc
index eb8ca3e..2a929b5 100644
--- a/libstdc++-v3/testsuite/26_numerics/valarray/range_access.cc
+++ b/libstdc++-v3/testsuite/26_numerics/valarray/range_access.cc
@@ -28,4 +28,7 @@ test01()
std::valarray<double> va{1.0, 2.0, 3.0};
std::begin(va);
std::end(va);
+ const auto& cva = va;
+ std::begin(cva);
+ std::end(cva);
}
diff --git a/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc b/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc
new file mode 100644
index 0000000..1c7a485
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/valarray/range_access2.cc
@@ -0,0 +1,36 @@
+// { dg-do compile }
+// { dg-options "-std=gnu++14" }
+
+// Copyright (C) 2015 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/>.
+
+// 26.6.10 valarray range access: [valarray.range]
+
+#include <iterator>
+#include <valarray>
+
+// PR libstdc++/67374
+void
+test01()
+{
+ std::valarray<double> va{1.0, 2.0, 3.0};
+ std::cbegin(va);
+ std::cend(va);
+ const auto& cva = va;
+ std::cbegin(cva);
+ std::cend(cva);
+}