libstdc++-v3/testsuite/std/ranges/p2325.cc

   1 // { dg-options "-std=gnu++20" }
   2 // { dg-do compile { target c++20 } }
   3 // { dg-require-effective-target hosted }
   4 // P2325R3 "Views should not be required to be default constructible"
   5
   6 #include <ranges>
   7 #include <iterator>
   8 #include <span>
   9 #include <sstream>
  10 #include <vector>
  11 #include <testsuite_iterators.h>
  12
  13 using namespace std;
  14
  15 template<default_initializable T> void f();
  16 template<typename T> requires weakly_incrementable<T> || ranges::view<T> void f();
  17
  18 void
  19 test01()
  20 {
  21   // Verify neither std::weakly_incrementable nor ranges::view require
  22   // default_initializable.
  23   f<int>(); // { dg-error "ambiguous" }
  24 }
  25
  26 void
  27 test02()
  28 {
  29   // Verify these iterators are not default constructible.
  30   static_assert(!default_initializable<insert_iterator<vector<int>>>);
  31   static_assert(!default_initializable<front_insert_iterator<vector<int>>>);
  32   static_assert(!default_initializable<back_insert_iterator<vector<int>>>);
  33   static_assert(!default_initializable<ostream_iterator<int>>);
  34
  35   using iter = ostream_iterator<int>;
  36
  37   // Verify common_iterator is conditionally default constructible.
  38   static_assert(!default_initializable<common_iterator<iter, unreachable_sentinel_t>>);
  39   static_assert(default_initializable<common_iterator<int*, unreachable_sentinel_t>>);
  40
  41   // Verify counted_iterator is conditionally default constructible.
  42   static_assert(!default_initializable<counted_iterator<iter>>);
  43   static_assert(default_initializable<counted_iterator<int*>>);
  44 }
  45
  46 void
  47 test03()
  48 {
  49   using iter = ostream_iterator<int>;
  50
  51   // Verify iota_view is conditionally default constructible.
  52   static_assert(!default_initializable<ranges::iota_view<iter>>);
  53   static_assert(!default_initializable<decltype(declval<ranges::iota_view<iter>>().begin())>);
  54   static_assert(default_initializable<ranges::iota_view<int>>);
  55   static_assert(default_initializable<decltype(declval<ranges::iota_view<int>>().begin())>);
  56
  57   // Verify subrange is conditionally default constructible.
  58   static_assert(!default_initializable<ranges::subrange<iter, unreachable_sentinel_t>>);
  59   static_assert(default_initializable<ranges::subrange<int*, unreachable_sentinel_t>>);
  60
  61   // Verify single_view is conditionally default constructible.
  62   static_assert(!default_initializable<ranges::single_view<iter>>);
  63   static_assert(default_initializable<ranges::single_view<int*>>);
  64 }
  65
  66 void
  67 test04()
  68 {
  69   // Verify basic_istream_view is not default constructible.
  70   using type = ranges::basic_istream_view<int, char, char_traits<char>>;
  71   static_assert(!default_initializable<type>);
  72   static_assert(!default_initializable<decltype(declval<type>().begin())>);
  73 }
  74
  75 void
  76 test05()
  77 {
  78   // Verify ref_view is not default constructible.
  79   static_assert(!default_initializable<ranges::ref_view<int[5]>>);
  80 }
  81
  82 template<auto adaptor>
  83 void
  84 test06()
  85 {
  86   auto f1 = [] (auto) { return true; };
  87   auto f2 = [i=0] (auto) { return true; };
  88   static_assert(default_initializable<decltype(views::single(0) | adaptor(f1))>);
  89   static_assert(!default_initializable<decltype(views::single(0) | adaptor(f2))>);
  90
  91   struct S { S() = delete; };
  92   static_assert(!default_initializable<decltype(views::single(declval<S>()) | adaptor(f1))>);
  93   static_assert(!default_initializable<decltype(views::single(declval<S>()) | adaptor(f2))>);
  94 }
  95
  96 // Verify filter_view, transform_view, take_while_view and drop_while_view are
  97 // conditionally default constructible.
  98 template void test06<views::filter>();
  99 template void test06<views::transform>();
 100 template void test06<views::take_while>();
 101 template void test06<views::drop_while>();
 102
 103 void
 104 test07()
 105 {
 106   // Verify join_view is conditionally default constructible.
 107   struct S { S() = delete; };
 108   using type1 = ranges::join_view<ranges::single_view<ranges::single_view<S>>>;
 109   static_assert(!default_initializable<type1>);
 110   using type2 = ranges::join_view<ranges::single_view<ranges::single_view<int>>>;
 111   static_assert(default_initializable<type2>);
 112 }
 113
 114 void
 115 test08()
 116 {
 117   // Verify lazy_split_view is conditionally default constructible.
 118   using type1 = ranges::lazy_split_view<ranges::ref_view<int[2]>, ranges::single_view<int>>;
 119   static_assert(!default_initializable<type1>);
 120   using type2 = ranges::lazy_split_view<ranges::single_view<int>, ranges::ref_view<int[2]>>;
 121   static_assert(!default_initializable<type2>);
 122   using type3 = ranges::lazy_split_view<ranges::ref_view<int[2]>, ranges::ref_view<int[2]>>;
 123   static_assert(!default_initializable<type3>);
 124   using type4 = ranges::lazy_split_view<ranges::single_view<int>, ranges::single_view<int>>;
 125   static_assert(default_initializable<type4>);
 126 }
 127
 128 void
 129 test08a()
 130 {
 131   // Verify split_view is conditionally default constructible.
 132   using type1 = ranges::split_view<ranges::ref_view<int[2]>, ranges::single_view<int>>;
 133   static_assert(!default_initializable<type1>);
 134   using type2 = ranges::split_view<ranges::single_view<int>, ranges::ref_view<int[2]>>;
 135   static_assert(!default_initializable<type2>);
 136   using type3 = ranges::split_view<ranges::ref_view<int[2]>, ranges::ref_view<int[2]>>;
 137   static_assert(!default_initializable<type3>);
 138   using type4 = ranges::split_view<ranges::single_view<int>, ranges::single_view<int>>;
 139   static_assert(default_initializable<type4>);
 140 }
 141
 142 void
 143 test09()
 144 {
 145   // Verify common_view is conditionally default constructible.
 146   using type1 = ranges::common_view<ranges::iota_view<ostream_iterator<int>>>;
 147   static_assert(!default_initializable<type1>);
 148   using type2 = ranges::common_view<ranges::iota_view<int*>>;
 149   static_assert(default_initializable<type2>);
 150 }
 151
 152 void
 153 test10()
 154 {
 155   // Verify reverse_view is conditionally default constructible.
 156   using type1 = ranges::reverse_view<ranges::ref_view<int[2]>>;
 157   static_assert(!default_initializable<type1>);
 158   using type2 = ranges::reverse_view<ranges::single_view<int>>;
 159   static_assert(default_initializable<type2>);
 160 }
 161
 162 void
 163 test11()
 164 {
 165   // Verify elements_view is conditionally default constructible.
 166   using type1 = ranges::elements_view<ranges::ref_view<pair<int,int>[2]>, 0>;
 167   static_assert(!default_initializable<type1>);
 168   using type2 = ranges::elements_view<ranges::single_view<pair<int,int>>, 0>;
 169   static_assert(default_initializable<type2>);
 170 }