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

   1 // Copyright (C) 2019-2021 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
  24 using std::same_as;
  25
  26 void
  27 test01()
  28 {
  29   int a[2] = {};
  30
  31   static_assert(same_as<decltype(std::ranges::cend(a)), const int*>);
  32   static_assert(noexcept(std::ranges::cend(a)));
  33   VERIFY( std::ranges::cend(a) == (a + 2) );
  34 }
  35
  36 struct R
  37 {
  38   int a[4] = { 0, 1, 2, 3 };
  39
  40   const int* begin() const { return nullptr; }
  41   friend const int* begin(const R&& r) noexcept { return nullptr; }
  42
  43   // Should be ignored because it doesn't return a sentinel for int*
  44   const long* end() const { return nullptr; }
  45
  46   friend int* end(R& r) { return r.a + 0; }
  47   friend int* end(R&& r) { return r.a + 1; }
  48   friend const int* end(const R& r) noexcept { return r.a + 2; }
  49   friend const int* end(const R&& r) noexcept { return r.a + 3; }
  50 };
  51
  52 struct RV // view on an R
  53 {
  54   R& r;
  55
  56   friend const int* begin(RV& rv) { return rv.r.begin(); }
  57   friend int* end(RV& rv) { return end(rv.r); }
  58   friend const int* begin(const RV& rv) noexcept { return rv.r.begin(); }
  59   friend const int* end(const RV& rv) noexcept { return end(std::as_const(rv.r)); }
  60 };
  61
  62 // Allow ranges::end to work with RV&&
  63 template<> constexpr bool std::ranges::enable_borrowed_range<RV> = true;
  64
  65 void
  66 test03()
  67 {
  68   R r;
  69   const R& c = r;
  70   VERIFY( std::ranges::cend(r) == std::ranges::end(c) );
  71   VERIFY( std::ranges::cend(c) == std::ranges::end(c) );
  72
  73   RV v{r};
  74   const RV cv{r};
  75   VERIFY( std::ranges::cend(std::move(v)) == std::ranges::end(c) );
  76   VERIFY( std::ranges::cend(std::move(cv)) == std::ranges::end(c) );
  77 }
  78
  79 struct RR
  80 {
  81   short s = 0;
  82   long l = 0;
  83   int a[4] = { 0, 1, 2, 3 };
  84
  85   const void* begin() const; // return type not an iterator
  86
  87   friend int* end(RR&) { throw 1; }
  88   short* end() noexcept { return &s; }
  89
  90   friend const long* begin(const RR&) noexcept;
  91   const long* end() const { return &l; }
  92
  93   friend int* begin(RR&&) noexcept;
  94   friend int* end(RR&& r) { return r.a + 1; }
  95
  96   friend const int* begin(const RR&&) noexcept;
  97   friend const int* end(const RR&& r) noexcept { return r.a + 3; }
  98 };
  99
 100 // N.B. this is a lie, begin/end on an RR rvalue will return a dangling pointer.
 101 template<> constexpr bool std::ranges::enable_borrowed_range<RR> = true;
 102
 103 void
 104 test04()
 105 {
 106   RR r;
 107   const RR& c = r;
 108   VERIFY( std::ranges::cend(r) == std::ranges::end(c) );
 109   VERIFY( std::ranges::cend(c) == std::ranges::end(c) );
 110
 111   VERIFY( std::ranges::cend(std::move(r)) == std::ranges::end(c) );
 112   VERIFY( std::ranges::cend(std::move(c)) == std::ranges::end(c) );
 113 }
 114
 115 int
 116 main()
 117 {
 118   test01();
 119   test03();
 120   test04();
 121 }