... a call to ranges::begin on an input range.
This implements LWG 3286. The new wording for the single-argument
subrange::subrange constructor is implemented by splitting the constructor into
two delegating constructors, one constrained by _S_store_size and the other by
!_S_store_size.
Tested on x86_64-pc-linux-gnu, both tests fail before the patch and pass with
the patch.
libstdc++-v3/ChangeLog:
LWG 3286 ranges::size is not required to be valid after a call to
ranges::begin on an input range
* include/std/ranges (subrange::subrange): Split single-argument
constructor into two, one constrained by _S_store_size and another by
!_S_store_size.
(take_view::begin): Call size() before calling ranges::begin(_M_base).
* testsuite/std/ranges/adaptors/lwg3286.cc: New test.
* testsuite/std/ranges/subrange/lwg3286.cc: New test.
---
libstdc++-v3/include/std/ranges | 26 +++++--
.../testsuite/std/ranges/adaptors/lwg3286.cc | 72 +++++++++++++++++++
.../testsuite/std/ranges/subrange/lwg3286.cc | 71 ++++++++++++++++++
3 files changed, 162 insertions(+), 7 deletions(-)
create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc
create mode 100644 libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index eb54b110c04..625eccaddba 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -281,12 +281,18 @@ namespace ranges
&& __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
&& convertible_to<sentinel_t<_Rng>, _Sent>
constexpr
- subrange(_Rng&& __r) requires (!_S_store_size || sized_range<_Rng>)
+ subrange(_Rng&& __r) requires _S_store_size && sized_range<_Rng>
+ : subrange{__r, ranges::size(__r)}
+ { }
+
+ template<__detail::__not_same_as<subrange> _Rng>
+ requires borrowed_range<_Rng>
+ && __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
+ && convertible_to<sentinel_t<_Rng>, _Sent>
+ constexpr
+ subrange(_Rng&& __r) requires (!_S_store_size)
: subrange{ranges::begin(__r), ranges::end(__r)}
- {
- if constexpr (_S_store_size)
- _M_size._M_size = ranges::size(__r);
- }
+ { }
template<borrowed_range _Rng>
requires __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It>
@@ -2037,7 +2043,10 @@ namespace views
if constexpr (random_access_range<_Vp>)
return ranges::begin(_M_base);
else
- return counted_iterator{ranges::begin(_M_base), size()};
+ {
+ auto __sz = size();
+ return counted_iterator{ranges::begin(_M_base), __sz};
+ }
}
else
return counted_iterator{ranges::begin(_M_base), _M_count};
@@ -2051,7 +2060,10 @@ namespace views
if constexpr (random_access_range<const _Vp>)
return ranges::begin(_M_base);
else
- return counted_iterator{ranges::begin(_M_base), size()};
+ {
+ auto __sz = size();
+ return counted_iterator{ranges::begin(_M_base), __sz};
+ }
}
else
return counted_iterator{ranges::begin(_M_base), _M_count};
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc
b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc
new file mode 100644
index 00000000000..07a0f63fe23
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc
@@ -0,0 +1,72 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <ranges>
+#include <testsuite_iterators.h>
+#include <testsuite_hooks.h>
+
+using __gnu_test::test_input_range;
+
+namespace ranges = std::ranges;
+namespace views = std::views;
+
+struct my_range
+{
+ static inline int x[] = {1,2,3};
+ static inline test_input_range<int> r{x};
+
+ bool called_begin = false;
+
+ auto
+ begin()
+ {
+ called_begin = true;
+ return r.begin();
+ }
+
+ auto
+ end()
+ {
+ return r.end();
+ }
+
+ ranges::range_difference_t<decltype(r)>
+ size()
+ {
+ VERIFY( !called_begin );
+ return 3;
+ }
+};
+
+void
+test01()
+{
+ my_range r;
+ static_assert(!ranges::forward_range<my_range>);
+ static_assert(ranges::sized_range<my_range>);
+ auto v = r | views::take(3);
+ auto i = ranges::begin(v);
+}
+
+int
+main()
+{
+ test01();
+}
diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc
b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc
new file mode 100644
index 00000000000..3ddec7004a7
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc
@@ -0,0 +1,71 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <ranges>
+#include <testsuite_iterators.h>
+#include <testsuite_hooks.h>
+
+using __gnu_test::test_input_range;
+
+namespace ranges = std::ranges;
+
+struct my_range
+{
+ static inline int x[] = {1,2,3};
+ static inline test_input_range<int> r{x};
+
+ bool called_begin = false;
+
+ auto
+ begin()
+ {
+ called_begin = true;
+ return r.begin();
+ }
+
+ auto
+ end()
+ {
+ return r.end();
+ }
+
+ ranges::range_difference_t<decltype(r)>
+ size()
+ {
+ VERIFY( !called_begin );
+ return 3;
+ }
+};
+
+void
+test01()
+{
+ my_range r;
+ static_assert(!ranges::forward_range<my_range>);
+ static_assert(ranges::sized_range<my_range>);
+ ranges::subrange sr = r;
+ VERIFY( ranges::size(sr) == 3 );
+}
+
+int
+main()
+{
+ test01();
+}
--
2.26.0.rc0
