test/libcxx/utilities/tuple/tuple.tuple/diagnose_reference_binding.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 // UNSUPPORTED: c++98, c++03
  11
  12 // <tuple>
  13
  14 // Test the diagnostics libc++ generates for invalid reference binding.
  15 // Libc++ attempts to diagnose the following cases:
  16 //  * Constructing an lvalue reference from an rvalue.
  17 //  * Constructing an rvalue reference from an lvalue.
  18
  19 #include <tuple>
  20 #include <string>
  21 #include <functional>
  22 #include <cassert>
  23
  24 static_assert(std::is_constructible<int&, std::reference_wrapper<int>>::value, "");
  25 static_assert(std::is_constructible<int const&, std::reference_wrapper<int>>::value, "");
  26
  27
  28 int main() {
  29     std::allocator<void> alloc;
  30     int x = 42;
  31     {
  32         std::tuple<int&> t(std::ref(x));
  33         assert(&std::get<0>(t) == &x);
  34         std::tuple<int&> t1(std::allocator_arg, alloc, std::ref(x));
  35         assert(&std::get<0>(t1) == &x);
  36     }
  37     {
  38         auto r = std::ref(x);
  39         auto const& cr = r;
  40         std::tuple<int&> t(r);
  41         assert(&std::get<0>(t) == &x);
  42         std::tuple<int&> t1(cr);
  43         assert(&std::get<0>(t1) == &x);
  44         std::tuple<int&> t2(std::allocator_arg, alloc, r);
  45         assert(&std::get<0>(t2) == &x);
  46         std::tuple<int&> t3(std::allocator_arg, alloc, cr);
  47         assert(&std::get<0>(t3) == &x);
  48     }
  49     {
  50         std::tuple<int const&> t(std::ref(x));
  51         assert(&std::get<0>(t) == &x);
  52         std::tuple<int const&> t2(std::cref(x));
  53         assert(&std::get<0>(t2) == &x);
  54         std::tuple<int const&> t3(std::allocator_arg, alloc, std::ref(x));
  55         assert(&std::get<0>(t3) == &x);
  56         std::tuple<int const&> t4(std::allocator_arg, alloc, std::cref(x));
  57         assert(&std::get<0>(t4) == &x);
  58     }
  59     {
  60         auto r = std::ref(x);
  61         auto cr = std::cref(x);
  62         std::tuple<int const&> t(r);
  63         assert(&std::get<0>(t) == &x);
  64         std::tuple<int const&> t2(cr);
  65         assert(&std::get<0>(t2) == &x);
  66         std::tuple<int const&> t3(std::allocator_arg, alloc, r);
  67         assert(&std::get<0>(t3) == &x);
  68         std::tuple<int const&> t4(std::allocator_arg, alloc, cr);
  69         assert(&std::get<0>(t4) == &x);
  70     }
  71 }