libcxx/test/std/iterators/iterator.range/begin-end.adl.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03
  10
  11 // Make sure that std::cbegin(x) effectively calls std::as_const(x).begin(), not x.cbegin().
  12 //
  13 // Also make sure that we don't get hijacked by ADL, see https://llvm.org/PR28927.
  14
  15 #include <cassert>
  16 #include <iterator>
  17
  18 #include "test_macros.h"
  19
  20 struct ArrayHijacker {
  21   friend constexpr int begin(ArrayHijacker (&)[3]) { return 42; }
  22   friend constexpr int end(ArrayHijacker (&)[3]) { return 42; }
  23   friend constexpr int begin(const ArrayHijacker (&)[3]) { return 42; }
  24   friend constexpr int end(const ArrayHijacker (&)[3]) { return 42; }
  25 };
  26
  27 struct ContainerHijacker {
  28   int* a_;
  29   constexpr int* begin() const { return a_; }
  30   constexpr int* end() const { return a_ + 3; }
  31   constexpr int* rbegin() const { return a_; }
  32   constexpr int* rend() const { return a_ + 3; }
  33   friend constexpr int begin(ContainerHijacker&) { return 42; }
  34   friend constexpr int end(ContainerHijacker&) { return 42; }
  35   friend constexpr int begin(const ContainerHijacker&) { return 42; }
  36   friend constexpr int end(const ContainerHijacker&) { return 42; }
  37   friend constexpr int cbegin(ContainerHijacker&) { return 42; }
  38   friend constexpr int cend(ContainerHijacker&) { return 42; }
  39   friend constexpr int cbegin(const ContainerHijacker&) { return 42; }
  40   friend constexpr int cend(const ContainerHijacker&) { return 42; }
  41   friend constexpr int rbegin(ContainerHijacker&) { return 42; }
  42   friend constexpr int rend(ContainerHijacker&) { return 42; }
  43   friend constexpr int rbegin(const ContainerHijacker&) { return 42; }
  44   friend constexpr int rend(const ContainerHijacker&) { return 42; }
  45   friend constexpr int crbegin(ContainerHijacker&) { return 42; }
  46   friend constexpr int crend(ContainerHijacker&) { return 42; }
  47   friend constexpr int crbegin(const ContainerHijacker&) { return 42; }
  48   friend constexpr int crend(const ContainerHijacker&) { return 42; }
  49 };
  50
  51 TEST_CONSTEXPR_CXX17 bool test() {
  52   {
  53     ArrayHijacker a[3] = {};
  54     assert(begin(a) == 42);
  55     assert(end(a) == 42);
  56     assert(std::begin(a) == a);
  57     assert(std::end(a) == a + 3);
  58 #if TEST_STD_VER > 11
  59     assert(std::cbegin(a) == a);
  60     assert(std::cend(a) == a + 3);
  61     assert(std::rbegin(a).base() == a + 3);
  62     assert(std::rend(a).base() == a);
  63     assert(std::crbegin(a).base() == a + 3);
  64     assert(std::crend(a).base() == a);
  65 #endif
  66   }
  67   {
  68     int a[3] = {};
  69     ContainerHijacker c{a};
  70     assert(begin(c) == 42);
  71     assert(end(c) == 42);
  72     assert(std::begin(c) == a);
  73     assert(std::end(c) == a + 3);
  74 #if TEST_STD_VER > 11
  75     assert(std::cbegin(c) == a);
  76     assert(std::cend(c) == a + 3);
  77     assert(std::rbegin(c) == a);
  78     assert(std::rend(c) == a + 3);
  79     assert(std::crbegin(c) == a);
  80     assert(std::crend(c) == a + 3);
  81 #endif
  82   }
  83   return true;
  84 }
  85
  86 int main(int, char**) {
  87   test();
  88 #if TEST_STD_VER >= 17
  89   static_assert(test());
  90 #endif
  91
  92   return 0;
  93 }