ceph/src/boost/libs/callable_traits/example/add_member_lvalue_reference.cpp

   1 /*<-
   2 Copyright Barrett Adair 2016-2017
   3 Distributed under the Boost Software License, Version 1.0.
   4 (See accompanying file LICENSE.md or copy at http ://boost.org/LICENSE_1_0.txt)
   5 ->*/
   6
   7 #include <boost/callable_traits/detail/config.hpp>
   8 #ifdef BOOST_CLBL_TRTS_DISABLE_REFERENCE_QUALIFIERS
   9 int main(){ return 0; }
  10 #else
  11
  12 //[ add_member_lvalue_reference
  13 #include <type_traits>
  14 #include <boost/callable_traits/add_member_lvalue_reference.hpp>
  15
  16 namespace ct = boost::callable_traits;
  17
  18 struct foo {};
  19
  20 int main() {
  21
  22     {
  23         using pmf = void(foo::*)();
  24         using expect = void(foo::*)() &;
  25         using test = ct::add_member_lvalue_reference_t<pmf>;
  26         static_assert(std::is_same<test, expect>::value, "");
  27     } {
  28         // add_member_lvalue_reference_t doesn't change anything when
  29         // the function type already has an lvalue qualifier.
  30         using pmf = void(foo::*)() &;
  31         using expect = void(foo::*)() &;
  32         using test = ct::add_member_lvalue_reference_t<pmf>;
  33         static_assert(std::is_same<test, expect>::value, "");
  34     } {
  35         // add_member_lvalue_reference_t models C++11 reference collapsing
  36         // rules, so that adding an lvalue qualifier to an
  37         // rvalue-qualified type will force the lvalue.
  38         using pmf = void(foo::*)() &&;
  39         using expect = void(foo::*)() &;
  40         using test = ct::add_member_lvalue_reference_t<pmf>;
  41         static_assert(std::is_same<test, expect>::value, "");
  42     } {
  43         // add_member_lvalue_reference_t can also be used to create "abominable"
  44         // function types.
  45         using f = void();
  46         using expect = void() &;
  47         using test = ct::add_member_lvalue_reference_t<f>;
  48         static_assert(std::is_same<test, expect>::value, "");
  49     }
  50 }
  51
  52 //]
  53 #endif //#ifdef BOOST_CLBL_TRTS_DISABLE_REFERENCE_QUALIFIERS