| Message ID | 20241004183404.218709-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | libstdc++: Implement LWG 3664 changes to ranges::distance | expand |
On Fri, 4 Oct 2024 at 19:37, Patrick Palka <ppalka@redhat.com> wrote: > > Tested on x86_64-pc-linux-gnu, does this look OK for trunk/backports? OK for all branches (assuming we already have LWG 3392 on the branches). > > -- >8 -- > > libstdc++-v3/ChangeLog: > > * include/bits/ranges_base.h (__distance_fn::operator()): > Adjust iterator/sentinel overloads as per LWG 3664. > * testsuite/24_iterators/range_operations/distance.cc: > Test LWG 3664 example. > --- > libstdc++-v3/include/bits/ranges_base.h | 14 +++++++------- > .../24_iterators/range_operations/distance.cc | 11 +++++++++++ > 2 files changed, 18 insertions(+), 7 deletions(-) > > diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h > index 137c3c98e14..cb2eba1f841 100644 > --- a/libstdc++-v3/include/bits/ranges_base.h > +++ b/libstdc++-v3/include/bits/ranges_base.h > @@ -947,7 +947,9 @@ namespace ranges > > struct __distance_fn final > { > - template<input_or_output_iterator _It, sentinel_for<_It> _Sent> > + // _GLIBCXX_RESOLVE_LIB_DEFECTS > + // 3664. LWG 3392 broke std::ranges::distance(a, a+3) > + template<typename _It, sentinel_for<_It> _Sent> > requires (!sized_sentinel_for<_Sent, _It>) > constexpr iter_difference_t<_It> > operator()[[nodiscard]](_It __first, _Sent __last) const > @@ -961,13 +963,11 @@ namespace ranges > return __n; > } > > - template<input_or_output_iterator _It, sized_sentinel_for<_It> _Sent> > + template<typename _It, sized_sentinel_for<decay_t<_It>> _Sent> > [[nodiscard]] > - constexpr iter_difference_t<_It> > - operator()(const _It& __first, const _Sent& __last) const > - { > - return __last - __first; > - } > + constexpr iter_difference_t<decay_t<_It>> > + operator()(_It&& __first, _Sent __last) const > + { return __last - static_cast<const decay_t<_It>&>(__first); } > > template<range _Range> > [[nodiscard]] > diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc > index 9a1d0c3efe8..336956936c2 100644 > --- a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc > +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc > @@ -144,6 +144,16 @@ test05() > VERIFY( std::ranges::distance(c4) == 5 ); > } > > +void > +test06() > +{ > + // LWG 3664 - LWG 3392 broke std::ranges::distance(a, a+3) > + int a[] = {1, 2, 3}; > + VERIFY( std::ranges::distance(a, a+3) == 3 ); > + VERIFY( std::ranges::distance(a, a) == 0 ); > + VERIFY( std::ranges::distance(a+3, a) == -3 ); > +} > + > int > main() > { > @@ -152,4 +162,5 @@ main() > test03(); > test04(); > test05(); > + test06(); > } > -- > 2.47.0.rc1 >
diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index 137c3c98e14..cb2eba1f841 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -947,7 +947,9 @@ namespace ranges struct __distance_fn final { - template<input_or_output_iterator _It, sentinel_for<_It> _Sent> + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3664. LWG 3392 broke std::ranges::distance(a, a+3) + template<typename _It, sentinel_for<_It> _Sent> requires (!sized_sentinel_for<_Sent, _It>) constexpr iter_difference_t<_It> operator()[[nodiscard]](_It __first, _Sent __last) const @@ -961,13 +963,11 @@ namespace ranges return __n; } - template<input_or_output_iterator _It, sized_sentinel_for<_It> _Sent> + template<typename _It, sized_sentinel_for<decay_t<_It>> _Sent> [[nodiscard]] - constexpr iter_difference_t<_It> - operator()(const _It& __first, const _Sent& __last) const - { - return __last - __first; - } + constexpr iter_difference_t<decay_t<_It>> + operator()(_It&& __first, _Sent __last) const + { return __last - static_cast<const decay_t<_It>&>(__first); } template<range _Range> [[nodiscard]] diff --git a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc index 9a1d0c3efe8..336956936c2 100644 --- a/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc +++ b/libstdc++-v3/testsuite/24_iterators/range_operations/distance.cc @@ -144,6 +144,16 @@ test05() VERIFY( std::ranges::distance(c4) == 5 ); } +void +test06() +{ + // LWG 3664 - LWG 3392 broke std::ranges::distance(a, a+3) + int a[] = {1, 2, 3}; + VERIFY( std::ranges::distance(a, a+3) == 3 ); + VERIFY( std::ranges::distance(a, a) == 0 ); + VERIFY( std::ranges::distance(a+3, a) == -3 ); +} + int main() { @@ -152,4 +162,5 @@ main() test03(); test04(); test05(); + test06(); }