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

   1 // Copyright (C) 2019-2023 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 <utility> // as_const
  23 #include <testsuite_hooks.h>
  24 #include <testsuite_iterators.h>
  25
  26 static_assert(__gnu_test::is_customization_point_object(std::ranges::cend));
  27
  28 using std::same_as;
  29
  30 void
  31 test01()
  32 {
  33   int a[2] = {};
  34
  35   static_assert(same_as<decltype(std::ranges::cend(a)), const int*>);
  36   static_assert(noexcept(std::ranges::cend(a)));
  37   VERIFY( std::ranges::cend(a) == (a + 2) );
  38 }
  39
  40 struct R
  41 {
  42   int a[4] = { 0, 1, 2, 3 };
  43
  44   const int* begin() const { return nullptr; }
  45   friend const int* begin(const R&& r) noexcept { return nullptr; }
  46
  47   // Should be ignored because it doesn't return a sentinel for int*
  48   const long* end() const { return nullptr; }
  49
  50   friend int* end(R& r) { return r.a + 0; }
  51   friend int* end(R&& r) { return r.a + 1; }
  52   friend const int* end(const R& r) noexcept { return r.a + 2; }
  53   friend const int* end(const R&& r) noexcept { return r.a + 3; }
  54 };
  55
  56 struct RV // view on an R
  57 {
  58   R& r;
  59
  60   friend const int* begin(RV& rv) { return rv.r.begin(); }
  61   friend int* end(RV& rv) { return end(rv.r); }
  62   friend const int* begin(const RV& rv) noexcept { return rv.r.begin(); }
  63   friend const int* end(const RV& rv) noexcept { return end(std::as_const(rv.r)); }
  64 };
  65
  66 // Allow ranges::end to work with RV&&
  67 template<> constexpr bool std::ranges::enable_borrowed_range<RV> = true;
  68
  69 void
  70 test03()
  71 {
  72   R r;
  73   const R& c = r;
  74   VERIFY( std::ranges::cend(r) == std::ranges::end(c) );
  75   VERIFY( std::ranges::cend(c) == std::ranges::end(c) );
  76
  77   RV v{r};
  78   const RV cv{r};
  79   VERIFY( std::ranges::cend(std::move(v)) == std::ranges::end(c) );
  80   VERIFY( std::ranges::cend(std::move(cv)) == std::ranges::end(c) );
  81 }
  82
  83 struct RR
  84 {
  85   short s = 0;
  86   long l = 0;
  87   int a[4] = { 0, 1, 2, 3 };
  88
  89   const void* begin() const; // return type not an iterator
  90
  91   friend int* end(RR&) { throw 1; }
  92   short* end() noexcept { return &s; }
  93
  94   friend const long* begin(const RR&) noexcept;
  95   const long* end() const { return &l; }
  96
  97   friend int* begin(RR&&) noexcept;
  98   friend int* end(RR&& r) { return r.a + 1; }
  99
 100   friend const int* begin(const RR&&) noexcept;
 101   friend const int* end(const RR&& r) noexcept { return r.a + 3; }
 102 };
 103
 104 // N.B. this is a lie, begin/end on an RR rvalue will return a dangling pointer.
 105 template<> constexpr bool std::ranges::enable_borrowed_range<RR> = true;
 106
 107 void
 108 test04()
 109 {
 110   RR r;
 111   const RR& c = r;
 112   VERIFY( std::ranges::cend(r) == std::ranges::end(c) );
 113   VERIFY( std::ranges::cend(c) == std::ranges::end(c) );
 114
 115   VERIFY( std::ranges::cend(std::move(r)) == std::ranges::end(c) );
 116   VERIFY( std::ranges::cend(std::move(c)) == std::ranges::end(c) );
 117 }
 118
 119 int
 120 main()
 121 {
 122   test01();
 123   test03();
 124   test04();
 125 }