libstdc++-v3/testsuite/20_util/function_objects/mem_fn/constexpr.cc

   1 // Copyright (C) 2019-2022 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++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <functional>
  22
  23 struct F
  24 {
  25   int i;
  26   constexpr int add(int j) { return i + j; }
  27 };
  28
  29 constexpr int
  30 test01(int i)
  31 {
  32   F f{i};
  33   return std::mem_fn(&F::i)(f);
  34 }
  35
  36 static_assert( test01(2) == 2 );
  37
  38 constexpr int
  39 test02(int i, int j)
  40 {
  41   F f{i};
  42   return std::mem_fn(&F::add)(&f, j);
  43 }
  44
  45 static_assert( test02(3, 4) == 7 );