libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/ctor.incomplete.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 // <functional>
  12 //
  13 // reference_wrapper<T>
  14 //
  15 //  where T is an incomplete type (since C++20)
  16
  17
  18 #include <functional>
  19 #include <cassert>
  20
  21 #include "test_macros.h"
  22
  23
  24 struct Foo;
  25
  26 Foo& get_foo();
  27
  28 void test() {
  29     Foo& foo = get_foo();
  30     std::reference_wrapper<Foo> ref{foo};
  31     assert(&ref.get() == &foo);
  32 }
  33
  34 struct Foo { };
  35
  36 Foo& get_foo() {
  37     static Foo foo;
  38     return foo;
  39 }
  40
  41 int main(int, char**) {
  42     test();
  43     return 0;
  44 }