From 96abc8222464fb1c4fba9f2ffe3fd1b081a9196e Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Thu, 9 Mar 2023 13:41:03 -0500
Subject: [PATCH] libstdc++: Implement LWG 3820/3849 changes to
cartesian_product_view
The LWG 3820 testcase revealed a bug in _M_advance, which this patch
also fixes.
libstdc++-v3/ChangeLog:
* include/std/ranges
(cartesian_product_view::_Iterator::_Iterator): Remove
constraint on default constructor as per LWG 3849.
(cartesian_product_view::_Iterator::_M_prev): Adjust position
of _Nm > 0 test as per LWG 3820.
(cartesian_product_view::_Iterator::_M_advance): Perform bounds
checking only on sized cartesian products.
* testsuite/std/ranges/cartesian_product/1.cc (test08): New test.
---
libstdc++-v3/include/std/ranges | 23 +++++++++++--------
.../std/ranges/cartesian_product/1.cc | 9 ++++++++
2 files changed, 22 insertions(+), 10 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index f6809413ee19..0725e700c476 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -8224,7 +8224,7 @@ namespace views::__adaptor
range_reference_t<__maybe_const_t<_Const, _Vs>>...>;
using difference_type = decltype(cartesian_product_view::_S_difference_type());
- _Iterator() requires forward_range<__maybe_const_t<_Const, _First>> = default;
+ _Iterator() = default;
constexpr
_Iterator(_Iterator<!_Const> __i)
@@ -8389,12 +8389,12 @@ namespace views::__adaptor
_M_prev()
{
auto& __it = std::get<_Nm>(_M_current);
- if (__it == ranges::begin(std::get<_Nm>(_M_parent->_M_bases)))
- {
- __it = __detail::__cartesian_common_arg_end(std::get<_Nm>(_M_parent->_M_bases));
- if constexpr (_Nm > 0)
+ if constexpr (_Nm > 0)
+ if (__it == ranges::begin(std::get<_Nm>(_M_parent->_M_bases)))
+ {
+ __it = __detail::__cartesian_common_arg_end(std::get<_Nm>(_M_parent->_M_bases));
_M_prev<_Nm - 1>();
- }
+ }
--__it;
}
@@ -8415,10 +8415,13 @@ namespace views::__adaptor
if constexpr (_Nm == 0)
{
#ifdef _GLIBCXX_ASSERTIONS
- auto __size = ranges::ssize(__r);
- auto __begin = ranges::begin(__r);
- auto __offset = __it - __begin;
- __glibcxx_assert(__offset + __x >= 0 && __offset + __x <= __size);
+ if constexpr (sized_range<__maybe_const_t<_Const, _First>>)
+ {
+ auto __size = ranges::ssize(__r);
+ auto __begin = ranges::begin(__r);
+ auto __offset = __it - __begin;
+ __glibcxx_assert(__offset + __x >= 0 && __offset + __x <= __size);
+ }
#endif
__it += __x;
}
diff --git a/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc b/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
index f52c2b96d586..ef2ece4a1686 100644
--- a/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
+++ b/libstdc++-v3/testsuite/std/ranges/cartesian_product/1.cc
@@ -201,6 +201,14 @@ test07()
VERIFY( i == 5 );
}
+void
+test08()
+{
+ // LWG 3820
+ auto r = views::cartesian_product(views::iota(0));
+ r.begin() += 3;
+}
+
int
main()
{
@@ -211,4 +219,5 @@ main()
test05();
static_assert(test06());
test07();
+ test08();
}
--
GitLab