libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_nothrow_swappable.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
  10
  11 // type_traits
  12
  13 // is_swappable
  14
  15 #include <type_traits>
  16 #include <vector>
  17 #include "test_macros.h"
  18
  19 namespace MyNS {
  20
  21 // Make the test types non-copyable so that generic std::swap is not valid.
  22 struct A {
  23   A(A const&) = delete;
  24   A& operator=(A const&) = delete;
  25 };
  26
  27 struct B {
  28   B(B const&) = delete;
  29   B& operator=(B const&) = delete;
  30 };
  31
  32 void swap(A&, A&) noexcept {}
  33 void swap(B&, B&) {}
  34
  35 struct M {
  36   M(M const&) = delete;
  37   M& operator=(M const&) = delete;
  38 };
  39
  40 void swap(M&&, M&&) noexcept {}
  41
  42 struct ThrowingMove {
  43     ThrowingMove(ThrowingMove&&) {}
  44     ThrowingMove& operator=(ThrowingMove&&) { return *this; }
  45 };
  46
  47 } // namespace MyNS
  48
  49 int main(int, char**)
  50 {
  51     using namespace MyNS;
  52     {
  53         // Test that is_swappable applies an lvalue reference to the type.
  54         static_assert(std::is_nothrow_swappable<int>::value, "");
  55         static_assert(std::is_nothrow_swappable<int&>::value, "");
  56         static_assert(!std::is_nothrow_swappable<M>::value, "");
  57         static_assert(!std::is_nothrow_swappable<M&&>::value, "");
  58     }
  59     {
  60         // Test that it correctly deduces the noexcept of swap.
  61         static_assert(std::is_nothrow_swappable<A>::value, "");
  62         static_assert(!std::is_nothrow_swappable<B>::value
  63                       && std::is_swappable<B>::value, "");
  64         static_assert(!std::is_nothrow_swappable<ThrowingMove>::value
  65                       && std::is_swappable<ThrowingMove>::value, "");
  66     }
  67     {
  68         // Test that it doesn't drop the qualifiers
  69         static_assert(!std::is_nothrow_swappable<const A>::value, "");
  70     }
  71     {
  72         // test non-referenceable types
  73         static_assert(!std::is_nothrow_swappable<void>::value, "");
  74         static_assert(!std::is_nothrow_swappable<int() const>::value, "");
  75         static_assert(!std::is_nothrow_swappable<int(int, ...) const &>::value, "");
  76     }
  77     {
  78         // test for presence of is_nothrow_swappable_v
  79         static_assert(std::is_nothrow_swappable_v<int>, "");
  80         static_assert(!std::is_nothrow_swappable_v<void>, "");
  81     }
  82
  83   return 0;
  84 }