[patch] libstdc++/67374 declare valarray begin/end overloads in <iterator>

[Jonathan Wakely <jwakely at redhat dot com>]

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>.

I considered adding a <bits/valarray_fwd.h> header with the
declarations, but I don't think that's worth it, so I'm just
declaring them directly in range_access.h

Tested powerpc64le-linux, committed to trunk. I'll probably commit to
the gcc-5 branch soon too.


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);
+}