libstdc++-v3/testsuite/26_numerics/headers/cmath/dr2192.cc

   1 // Copyright (C) 2016-2021 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++11 } }
  19
  20 // NB: Don't include any other headers in this file.
  21 // LWG 2192 requires <cmath> to declare overloads for integral types.
  22 #include <cmath>
  23
  24 template<typename, typename> struct is_same { enum { value = 0 }; };
  25 template<typename T> struct is_same<T, T> { enum { value = 1 }; };
  26
  27 template<typename T, typename U = T>
  28   constexpr bool check(T val) {
  29     return is_same<decltype(std::abs(val)), U>::value;
  30   }
  31
  32 // Unsigned arguments that promote to int are valid:
  33 static_assert( check<short, int>(1), "abs((short)1) returns int" );
  34 static_assert( check<unsigned short, int>(1),
  35               "abs((unsigned short)1) returns int" );
  36
  37 static_assert( check(1),        "abs(1) returns int" );
  38 static_assert( check(1l),       "abs(1l) returns long" );
  39 static_assert( check(1ll),      "abs(1ll) returns long long" );