| Message ID | 20210427145542.2951069-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | libstdc++: Fix up lambda in join_view::_Iterator::operator++ [PR100290] | expand |
On 27/04/21 10:55 -0400, Patrick Palka via Libstdc++ wrote: >Currently, the return type of this lambda is decltype(auto), so it ends >up returning a copy of _M_parent->_M_inner rather than a reference to it >when _S_ref_glvalue is false. Hence _M_inner and ranges::end(__inner_range) >are respectively an iterator and sentinel for different ranges, so >comparing them is undefined. > >Tested on x86_64-pc-linux-gnu, does this look OK for trunk/11/10? Yes for all three, thanks. >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. >--- > 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(); > } >-- >2.31.1.362.g311531c9de >
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(); }