libstdc++-v3/testsuite/std/ranges/access/rend.cc

   1 // Copyright (C) 2019-2020 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do run { target c++2a } }
  20
  21 #include <ranges>
  22 #include <testsuite_hooks.h>
  23 #include <testsuite_iterators.h>
  24
  25 struct R1
  26 {
  27   int i = 0;
  28   int j = 0;
  29
  30   constexpr const int* rbegin() const { return &i; }
  31   constexpr const int* rend() const { return &i + 1; }
  32   friend constexpr const int* rbegin(const R1&&); // not defined
  33   friend constexpr const int* rend(const R1&&); // not defined
  34 };
  35
  36 // N.B. this is a lie, rend on an R1 rvalue will return a dangling pointer.
  37 template<> constexpr bool std::ranges::enable_safe_range<R1> = true;
  38
  39 void
  40 test01()
  41 {
  42   constexpr R1 r;
  43   static_assert( std::ranges::rend(r) == &r.i + 1 );
  44   static_assert( std::ranges::rend(std::move(r)) == &r.i + 1 );
  45 }
  46
  47 struct R2
  48 {
  49   int a[2] = { };
  50   long l[2] = { };
  51
  52   constexpr const int* begin() const { return a; }
  53   constexpr const int* end() const { return a + 2; }
  54
  55   friend constexpr const long* begin(const R2&& r) { return r.l; }
  56   friend constexpr const long* end(const R2&& r) { return r.l + 2; }
  57 };
  58
  59 // N.B. this is a lie, begin/end on an R2 rvalue will return a dangling pointer.
  60 template<> constexpr bool std::ranges::enable_safe_range<R2> = true;
  61
  62 void
  63 test02()
  64 {
  65   constexpr R2 r;
  66   static_assert( std::ranges::rend(r)
  67       == std::make_reverse_iterator(std::ranges::begin(r)) );
  68   static_assert( std::ranges::rend(std::move(r))
  69       == std::make_reverse_iterator(std::ranges::begin(std::move(r))) );
  70 }
  71
  72 struct R3
  73 {
  74   int i = 0;
  75
  76   int* rbegin() noexcept { return &i + 1; }
  77   long* rend() noexcept { return nullptr; } // not a sentinel for rbegin()
  78
  79   friend long* rbegin(R3&) noexcept { return nullptr; }
  80   friend int* rend(R3& r) { return &r.i; }
  81 };
  82
  83 void
  84 test03()
  85 {
  86   R3 r;
  87   auto i1 = std::ranges::rbegin(r);
  88   auto i2 = rend(r);
  89   static_assert( std::sentinel_for<decltype(i2), decltype(i1)> );
  90   // VERIFY( std::ranges::rend(r) == r.i );
  91   // static_assert( !noexcept(std::ranges::rend(r)) );
  92 }
  93
  94 void
  95 test04()
  96 {
  97   using __gnu_test::test_range;
  98   using __gnu_test::bidirectional_iterator_wrapper;
  99
 100   int a[2] = { };
 101   test_range<int, bidirectional_iterator_wrapper> r(a);
 102   VERIFY( std::ranges::rend(r) == std::make_reverse_iterator(std::ranges::begin(r)) );
 103 }
 104
 105 int
 106 main()
 107 {
 108   test01();
 109   test02();
 110   test03();
 111 }