libstdc++-v3/testsuite/26_numerics/bit/bit.pow.two/ceil2_neg.cc

   1 // Copyright (C) 2019-2020 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++2a -D_GLIBCXX_ASSERTIONS" }
  19 // { dg-do run { target c++2a } }
  20 // { dg-xfail-run-if "__glibcxx_assert in ceil2 should fail" { *-*-* } }
  21
  22 #include <bit>
  23
  24 // P1355R2: not a constant expression if the result is not representable
  25
  26 template<auto N, typename = void>
  27   struct ceil2_valid
  28   : std::false_type { };
  29
  30 template<auto N>
  31   struct ceil2_valid<N, std::void_t<char[(std::ceil2(N), 1)]>>
  32   : std::true_type { };
  33
  34 template<typename T>
  35   constexpr T max = std::numeric_limits<T>::max();
  36 template<typename T>
  37   constexpr T maxpow2 = T(1) << (std::numeric_limits<T>::digits - 1);
  38
  39 static_assert( ceil2_valid<maxpow2<unsigned char>>() );
  40 static_assert( !ceil2_valid<maxpow2<unsigned char> + (unsigned char)1>() );
  41
  42 static_assert( !ceil2_valid<max<unsigned char>>() );
  43 static_assert( !ceil2_valid<max<unsigned char> - (unsigned char)1>() );
  44
  45 static_assert( ceil2_valid<maxpow2<unsigned short>>() );
  46 static_assert( !ceil2_valid<maxpow2<unsigned short> + (unsigned short)1>() );
  47 static_assert( !ceil2_valid<max<unsigned short>>() );
  48 static_assert( !ceil2_valid<max<unsigned short> - (unsigned short)1>() );
  49
  50 static_assert( ceil2_valid<maxpow2<unsigned int>>() );
  51 static_assert( !ceil2_valid<maxpow2<unsigned int> + 1u>() );
  52 static_assert( !ceil2_valid<max<unsigned int>>() );
  53 static_assert( !ceil2_valid<max<unsigned int> - 1u>() );
  54
  55 static_assert( ceil2_valid<maxpow2<unsigned long>>() );
  56 static_assert( !ceil2_valid<maxpow2<unsigned long> + 1ul>() );
  57 static_assert( !ceil2_valid<max<unsigned long>>() );
  58 static_assert( !ceil2_valid<max<unsigned long> - 1ul>() );
  59
  60 static_assert( ceil2_valid<maxpow2<unsigned long long>>() );
  61 static_assert( !ceil2_valid<maxpow2<unsigned long long> + 1ull>() );
  62 static_assert( !ceil2_valid<max<unsigned long long>>() );
  63 static_assert( !ceil2_valid<max<unsigned long long> - 1ull>() );
  64
  65 void
  66 test01()
  67 {
  68   std::ceil2( maxpow2<unsigned> + 1u ); // should fail __glibcxx_assert
  69 }
  70
  71 int main()
  72 {
  73   test01();
  74 }