21 using RangeEmptyT = decltype(std::ranges::empty);
38 static_assert(!std::ranges::empty(array_of_incomplete));
39 static_assert(!std::ranges::empty(std::move(array_of_incomplete)));
40 static_assert(!std::ranges::empty(std::as_const(array_of_incomplete)));
41 static_assert(!std::ranges::empty(static_cast<const Incomplete(&&)[42]>(array_of_incomplete)));
50   bool empty();
55   constexpr bool empty() const { return true; }  in empty()  function
57   friend bool empty(const HasMemberAndFunction&) { return false; }  in empty()  function
61   BadReturnType empty() { return {}; }  in empty()  function
69   constexpr BoolConvertible empty() noexcept { return {}; }  in empty()  function
71 static_assert(!noexcept(std::ranges::empty(BoolConvertibleReturnType())));
82   assert(std::ranges::empty(a));  in testEmptyMember()
85   assert(std::ranges::empty(b));  in testEmptyMember()
109   assert(!std::ranges::empty(a));  in testUsingRangesSize()
111   assert(std::ranges::empty(b));  in testUsingRangesSize()
114   assert(!std::ranges::empty(c));  in testUsingRangesSize()
116   assert(std::ranges::empty(d));  in testUsingRangesSize()
119   assert(std::ranges::empty(e));  in testUsingRangesSize()
145   constexpr bool empty() { return false; }  in empty()  function
149   bool empty() &&;
156   assert(std::ranges::empty(a));  in testBeginEqualsEnd()
159   assert(std::ranges::empty(d));  in testBeginEqualsEnd()
162   assert(!std::ranges::empty(e)); // e.empty()  in testBeginEqualsEnd()
163   assert(std::ranges::empty(std::as_const(e))); // e.begin() == e.end()  in testBeginEqualsEnd()
165   assert(std::ranges::empty(EvilBeginEnd()));  in testBeginEqualsEnd()