libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.sfinae.compile.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, c++11, c++14, c++17
  10
  11 // <iterator>
  12 //
  13 // reverse_iterator
  14 //
  15 // pointer operator->() const;
  16
  17 #include <iterator>
  18
  19 #include <type_traits>
  20 #include "test_iterators.h"
  21
  22 template <class T>
  23 concept HasArrow = requires(T t) { t.operator->(); };
  24
  25 struct simple_bidirectional_iterator {
  26     using iterator_category = std::bidirectional_iterator_tag;
  27     using value_type = int;
  28     using difference_type = int;
  29     using pointer = int*;
  30     using reference = int&;
  31
  32     reference operator*() const;
  33     pointer operator->() const;
  34
  35     simple_bidirectional_iterator& operator++();
  36     simple_bidirectional_iterator& operator--();
  37     simple_bidirectional_iterator operator++(int);
  38     simple_bidirectional_iterator operator--(int);
  39
  40     friend bool operator==(const simple_bidirectional_iterator&, const simple_bidirectional_iterator&);
  41 };
  42 static_assert( std::bidirectional_iterator<simple_bidirectional_iterator>);
  43 static_assert(!std::random_access_iterator<simple_bidirectional_iterator>);
  44
  45 using PtrRI = std::reverse_iterator<int*>;
  46 static_assert( HasArrow<PtrRI>);
  47
  48 using PtrLikeRI = std::reverse_iterator<simple_bidirectional_iterator>;
  49 static_assert( HasArrow<PtrLikeRI>);
  50
  51 // `bidirectional_iterator` from `test_iterators.h` doesn't define `operator->`.
  52 using NonPtrRI = std::reverse_iterator<bidirectional_iterator<int*>>;
  53 static_assert(!HasArrow<NonPtrRI>);