https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81964
On Thu, 24 Aug 2017 11:55:58 +0300
Petr Ovtchenkov <p...@void-ptr.info> wrote:
> istream_iterator do unexpected read from stream
> when initialized by istream&.
>
> It is not required from increment operators of istream_iterator
> that _M_ok will be true as precondition.
> ---
> libstdc++-v3/include/bits/stream_iterator.h | 19 +++++-----
> .../24_iterators/istream_iterator/81964.cc | 42
> ++++++++++++++++++++++
> 2 files changed, 50 insertions(+), 11 deletions(-)
> create mode 100644
> libstdc++-v3/testsuite/24_iterators/istream_iterator/81964.cc
>
> diff --git a/libstdc++-v3/include/bits/stream_iterator.h
> b/libstdc++-v3/include/bits/stream_iterator.h index f9c6ba6..26959ce 100644
> --- a/libstdc++-v3/include/bits/stream_iterator.h
> +++ b/libstdc++-v3/include/bits/stream_iterator.h
> @@ -56,8 +56,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> private:
> istream_type* _M_stream;
> - _Tp _M_value;
> - bool _M_ok;
> + mutable _Tp _M_value;
> + mutable bool _M_ok;
>
> public:
> /// Construct end of input stream iterator.
> @@ -66,8 +66,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> /// Construct start of input stream iterator.
> istream_iterator(istream_type& __s)
> - : _M_stream(&__s)
> - { _M_read(); }
> + : _M_stream(&__s), _M_value(), _M_ok(false)
> + { }
>
> istream_iterator(const istream_iterator& __obj)
> : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
> @@ -77,6 +77,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> const _Tp&
> operator*() const
> {
> + if (!_M_ok) {
> + _M_read();
> + }
> __glibcxx_requires_cond(_M_ok,
> _M_message(__gnu_debug::__msg_deref_istream)
> ._M_iterator(*this));
> @@ -89,9 +92,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> istream_iterator&
> operator++()
> {
> - __glibcxx_requires_cond(_M_ok,
> - _M_message(__gnu_debug::__msg_inc_istream)
> - ._M_iterator(*this));
> _M_read();
> return *this;
> }
> @@ -99,9 +99,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> istream_iterator
> operator++(int)
> {
> - __glibcxx_requires_cond(_M_ok,
> - _M_message(__gnu_debug::__msg_inc_istream)
> - ._M_iterator(*this));
> istream_iterator __tmp = *this;
> _M_read();
> return __tmp;
> @@ -113,7 +110,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> private:
> void
> - _M_read()
> + _M_read() const
> {
> _M_ok = (_M_stream && *_M_stream) ? true : false;
> if (_M_ok)
> diff --git a/libstdc++-v3/testsuite/24_iterators/istream_iterator/81964.cc
> b/libstdc++-v3/testsuite/24_iterators/istream_iterator/81964.cc new file mode
> 100644
> index 0000000..f58fc87
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/24_iterators/istream_iterator/81964.cc
> @@ -0,0 +1,42 @@
> +// { dg-options "-std=gnu++11" }
> +
> +// Copyright (C) 2017 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/>.
> +
> +#include <sstream>
> +#include <iterator>
> +#include <testsuite_hooks.h>
> +
> +// libstdc++/81964
> +void test0x()
> +{
> + using namespace std;
> + bool test __attribute__((unused)) = true;
> +
> + std::istringstream s("1 2");
> + std::istream_iterator<int> ii1(s);
> + std::istream_iterator<int> ii2(s);
> +
> + VERIFY( *ii2 == 1 );
> + VERIFY( *ii1 == 2 );
> +}
> +
> +int main()
> +{
> + test0x();
> + return 0;
> +}
> --
> 2.10.1
>
