| // { dg-options "-std=gnu++20" } |
| // { dg-do compile { target c++20 } } |
| // { dg-require-effective-target hosted } |
| // P2325R3 "Views should not be required to be default constructible" |
| |
| #include <ranges> |
| #include <iterator> |
| #include <span> |
| #include <sstream> |
| #include <vector> |
| #include <testsuite_iterators.h> |
| |
| using namespace std; |
| |
| template<default_initializable T> void f(); |
| template<typename T> requires weakly_incrementable<T> || ranges::view<T> void f(); |
| |
| void |
| test01() |
| { |
| // Verify neither std::weakly_incrementable nor ranges::view require |
| // default_initializable. |
| f<int>(); // { dg-error "ambiguous" } |
| } |
| |
| void |
| test02() |
| { |
| // Verify these iterators are not default constructible. |
| static_assert(!default_initializable<insert_iterator<vector<int>>>); |
| static_assert(!default_initializable<front_insert_iterator<vector<int>>>); |
| static_assert(!default_initializable<back_insert_iterator<vector<int>>>); |
| static_assert(!default_initializable<ostream_iterator<int>>); |
| |
| using iter = ostream_iterator<int>; |
| |
| // Verify common_iterator is conditionally default constructible. |
| static_assert(!default_initializable<common_iterator<iter, unreachable_sentinel_t>>); |
| static_assert(default_initializable<common_iterator<int*, unreachable_sentinel_t>>); |
| |
| // Verify counted_iterator is conditionally default constructible. |
| static_assert(!default_initializable<counted_iterator<iter>>); |
| static_assert(default_initializable<counted_iterator<int*>>); |
| } |
| |
| void |
| test03() |
| { |
| using iter = ostream_iterator<int>; |
| |
| // Verify iota_view is conditionally default constructible. |
| static_assert(!default_initializable<ranges::iota_view<iter>>); |
| static_assert(!default_initializable<decltype(declval<ranges::iota_view<iter>>().begin())>); |
| static_assert(default_initializable<ranges::iota_view<int>>); |
| static_assert(default_initializable<decltype(declval<ranges::iota_view<int>>().begin())>); |
| |
| // Verify subrange is conditionally default constructible. |
| static_assert(!default_initializable<ranges::subrange<iter, unreachable_sentinel_t>>); |
| static_assert(default_initializable<ranges::subrange<int*, unreachable_sentinel_t>>); |
| |
| // Verify single_view is conditionally default constructible. |
| static_assert(!default_initializable<ranges::single_view<iter>>); |
| static_assert(default_initializable<ranges::single_view<int*>>); |
| } |
| |
| void |
| test04() |
| { |
| // Verify basic_istream_view is not default constructible. |
| using type = ranges::basic_istream_view<int, char, char_traits<char>>; |
| static_assert(!default_initializable<type>); |
| static_assert(!default_initializable<decltype(declval<type>().begin())>); |
| } |
| |
| void |
| test05() |
| { |
| // Verify ref_view is not default constructible. |
| static_assert(!default_initializable<ranges::ref_view<int[5]>>); |
| } |
| |
| template<auto adaptor> |
| void |
| test06() |
| { |
| auto f1 = [] (auto) { return true; }; |
| auto f2 = [i=0] (auto) { return true; }; |
| static_assert(default_initializable<decltype(views::single(0) | adaptor(f1))>); |
| static_assert(!default_initializable<decltype(views::single(0) | adaptor(f2))>); |
| |
| struct S { S() = delete; }; |
| static_assert(!default_initializable<decltype(views::single(declval<S>()) | adaptor(f1))>); |
| static_assert(!default_initializable<decltype(views::single(declval<S>()) | adaptor(f2))>); |
| } |
| |
| // Verify filter_view, transform_view, take_while_view and drop_while_view are |
| // conditionally default constructible. |
| template void test06<views::filter>(); |
| template void test06<views::transform>(); |
| template void test06<views::take_while>(); |
| template void test06<views::drop_while>(); |
| |
| void |
| test07() |
| { |
| // Verify join_view is conditionally default constructible. |
| struct S { S() = delete; }; |
| using type1 = ranges::join_view<ranges::single_view<ranges::single_view<S>>>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::join_view<ranges::single_view<ranges::single_view<int>>>; |
| static_assert(default_initializable<type2>); |
| } |
| |
| void |
| test08() |
| { |
| // Verify lazy_split_view is conditionally default constructible. |
| using type1 = ranges::lazy_split_view<ranges::ref_view<int[2]>, ranges::single_view<int>>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::lazy_split_view<ranges::single_view<int>, ranges::ref_view<int[2]>>; |
| static_assert(!default_initializable<type2>); |
| using type3 = ranges::lazy_split_view<ranges::ref_view<int[2]>, ranges::ref_view<int[2]>>; |
| static_assert(!default_initializable<type3>); |
| using type4 = ranges::lazy_split_view<ranges::single_view<int>, ranges::single_view<int>>; |
| static_assert(default_initializable<type4>); |
| } |
| |
| void |
| test08a() |
| { |
| // Verify split_view is conditionally default constructible. |
| using type1 = ranges::split_view<ranges::ref_view<int[2]>, ranges::single_view<int>>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::split_view<ranges::single_view<int>, ranges::ref_view<int[2]>>; |
| static_assert(!default_initializable<type2>); |
| using type3 = ranges::split_view<ranges::ref_view<int[2]>, ranges::ref_view<int[2]>>; |
| static_assert(!default_initializable<type3>); |
| using type4 = ranges::split_view<ranges::single_view<int>, ranges::single_view<int>>; |
| static_assert(default_initializable<type4>); |
| } |
| |
| void |
| test09() |
| { |
| // Verify common_view is conditionally default constructible. |
| using type1 = ranges::common_view<ranges::iota_view<ostream_iterator<int>>>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::common_view<ranges::iota_view<int*>>; |
| static_assert(default_initializable<type2>); |
| } |
| |
| void |
| test10() |
| { |
| // Verify reverse_view is conditionally default constructible. |
| using type1 = ranges::reverse_view<ranges::ref_view<int[2]>>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::reverse_view<ranges::single_view<int>>; |
| static_assert(default_initializable<type2>); |
| } |
| |
| void |
| test11() |
| { |
| // Verify elements_view is conditionally default constructible. |
| using type1 = ranges::elements_view<ranges::ref_view<pair<int,int>[2]>, 0>; |
| static_assert(!default_initializable<type1>); |
| using type2 = ranges::elements_view<ranges::single_view<pair<int,int>>, 0>; |
| static_assert(default_initializable<type2>); |
| } |