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// { 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>);
}
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