[gcc r11-8310] libstdc++: Fix up lambda in join_view::_Iterator::operator++ [PR100290]
Patrick Palka
ppalka@gcc.gnu.org
Tue Apr 27 21:24:58 GMT 2021
https://gcc.gnu.org/g:c6a94ee07e378632c4fcea2eead30a18ce15a6c3
commit r11-8310-gc6a94ee07e378632c4fcea2eead30a18ce15a6c3
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Apr 27 14:07:46 2021 -0400
libstdc++: Fix up lambda in join_view::_Iterator::operator++ [PR100290]
Currently, the return type of this lambda is decltype(auto), so the
lambda ends up returning a copy of _M_parent->_M_inner rather than a
reference to it when _S_ref_glvalue is false. This means _M_inner and
ranges::end(__inner_range) are respectively an iterator and sentinel for
different ranges, so comparing them is undefined.
libstdc++-v3/ChangeLog:
PR libstdc++/100290
* include/std/ranges (join_view::_Iterator::operator++): Correct
the return type of the lambda to avoid returning a copy of
_M_parent->_M_inner.
* testsuite/std/ranges/adaptors/join.cc (test10): New test.
(cherry picked from commit 85ef4b8d4eb3313a48b79c7e752891f9646bb246)
Diff:
---
libstdc++-v3/include/std/ranges | 2 +-
libstdc++-v3/testsuite/std/ranges/adaptors/join.cc | 11 +++++++++++
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 74075a2d6d3..09115e9b45f 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -2389,7 +2389,7 @@ namespace views::__adaptor
constexpr _Iterator&
operator++()
{
- auto&& __inner_range = [this] () -> decltype(auto) {
+ auto&& __inner_range = [this] () -> auto&& {
if constexpr (_S_ref_is_glvalue)
return *_M_outer;
else
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
index fb06a7698af..e6c71d771de 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc
@@ -160,6 +160,16 @@ test09()
static_assert(!requires { 0 | join; });
}
+void
+test10()
+{
+ // PR libstdc++/100290
+ auto v = views::single(0)
+ | views::transform([](const auto& s) { return views::single(s); })
+ | views::join;
+ VERIFY( ranges::next(v.begin()) == v.end() );
+}
+
int
main()
{
@@ -172,4 +182,5 @@ main()
test07();
test08();
test09();
+ test10();
}
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