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

   1 // Copyright (C) 2019-2023 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 bit_ceil should fail" { *-*-* } }
  21
  22 #include <bit>
  23 #include <limits>
  24
  25 // P1355R2: not a constant expression if the result is not representable
  26
  27 template<auto N, typename = void>
  28   struct bit_ceil_valid
  29   : std::false_type { };
  30
  31 template<auto N>
  32   struct bit_ceil_valid<N, std::void_t<char[(std::bit_ceil(N), 1)]>>
  33   : std::true_type { };
  34
  35 template<typename T>
  36   constexpr T max = std::numeric_limits<T>::max();
  37 template<typename T>
  38   constexpr T maxpow2 = T(1) << (std::numeric_limits<T>::digits - 1);
  39
  40 static_assert( bit_ceil_valid<maxpow2<unsigned char>>() );
  41 static_assert( !bit_ceil_valid<maxpow2<unsigned char> + (unsigned char)1>() );
  42
  43 static_assert( !bit_ceil_valid<max<unsigned char>>() );
  44 static_assert( !bit_ceil_valid<max<unsigned char> - (unsigned char)1>() );
  45
  46 static_assert( bit_ceil_valid<maxpow2<unsigned short>>() );
  47 static_assert( !bit_ceil_valid<maxpow2<unsigned short> + (unsigned short)1>() );
  48 static_assert( !bit_ceil_valid<max<unsigned short>>() );
  49 static_assert( !bit_ceil_valid<max<unsigned short> - (unsigned short)1>() );
  50
  51 static_assert( bit_ceil_valid<maxpow2<unsigned int>>() );
  52 static_assert( !bit_ceil_valid<maxpow2<unsigned int> + 1u>() );
  53 static_assert( !bit_ceil_valid<max<unsigned int>>() );
  54 static_assert( !bit_ceil_valid<max<unsigned int> - 1u>() );
  55
  56 static_assert( bit_ceil_valid<maxpow2<unsigned long>>() );
  57 static_assert( !bit_ceil_valid<maxpow2<unsigned long> + 1ul>() );
  58 static_assert( !bit_ceil_valid<max<unsigned long>>() );
  59 static_assert( !bit_ceil_valid<max<unsigned long> - 1ul>() );
  60
  61 static_assert( bit_ceil_valid<maxpow2<unsigned long long>>() );
  62 static_assert( !bit_ceil_valid<maxpow2<unsigned long long> + 1ull>() );
  63 static_assert( !bit_ceil_valid<max<unsigned long long>>() );
  64 static_assert( !bit_ceil_valid<max<unsigned long long> - 1ull>() );
  65
  66 void
  67 test01()
  68 {
  69   std::bit_ceil( maxpow2<unsigned> + 1u ); // should fail __glibcxx_assert
  70 }
  71
  72 int main()
  73 {
  74   test01();
  75 }