libstdc++-v3/testsuite/20_util/function/cons/deduction.cc

   1 // Copyright (C) 2017-2020 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++17" }
  19 // { dg-do compile { target c++17 } }
  20
  21 #include <functional>
  22
  23 template<typename T, typename U> struct require_same;
  24 template<typename T> struct require_same<T, T> { using type = void; };
  25
  26 template<typename T, typename U>
  27   typename require_same<T, U>::type
  28   check_type(U&) { }
  29
  30 void f0v();
  31 void f0vn() noexcept;
  32 int f0i();
  33 int f0in() noexcept;
  34 long f1l(int&);
  35 long f1ln(double*) noexcept;
  36
  37 void
  38 test01()
  39 {
  40   std::function func1 = f0v;
  41   check_type<std::function<void()>>(func1);
  42
  43   std::function func2 = f0vn;
  44   check_type<std::function<void()>>(func2);
  45
  46   std::function func3 = f0i;
  47   check_type<std::function<int()>>(func3);
  48
  49   std::function func4 = f0in;
  50   check_type<std::function<int()>>(func4);
  51
  52   std::function func5 = f1l;
  53   check_type<std::function<long(int&)>>(func5);
  54
  55   std::function func6 = f1ln;
  56   check_type<std::function<long(double*)>>(func6);
  57
  58   std::function func5a = func5;
  59   check_type<std::function<long(int&)>>(func5a);
  60
  61   std::function func6a = func6;
  62   check_type<std::function<long(double*)>>(func6a);
  63 }
  64
  65 struct X {
  66   int operator()(const short&, void*);
  67 };
  68
  69 struct Y {
  70   void operator()(int) const & noexcept;
  71 };
  72
  73 void
  74 test02()
  75 {
  76   X x;
  77   std::function func1 = x;
  78   check_type<std::function<int(const short&, void*)>>(func1);
  79
  80   Y y;
  81   std::function func2 = y;
  82   check_type<std::function<void(int)>>(func2);
  83
  84   std::function func3 = [&x](float) -> X& { return x; };
  85   check_type<std::function<X&(float)>>(func3);
  86 }