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

   1 // Copyright (C) 2019-2024 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-do compile { target c++20 } }
  19
  20 #include <functional>
  21
  22 struct F
  23 {
  24   int i;
  25   constexpr int add(int j) { return i + j; }
  26 };
  27
  28 constexpr int
  29 test01(int i)
  30 {
  31   F f{i};
  32   return std::mem_fn(&F::i)(f);
  33 }
  34
  35 static_assert( test01(2) == 2 );
  36
  37 constexpr int
  38 test02(int i, int j)
  39 {
  40   F f{i};
  41   return std::mem_fn(&F::add)(&f, j);
  42 }
  43
  44 static_assert( test02(3, 4) == 7 );