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

   1 // Copyright (C) 2018-2024 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 <bit>
  21 #include <limits>
  22
  23 template<typename UInt>
  24 constexpr auto
  25 test(UInt x)
  26 -> decltype(std::bit_width(x))
  27 {
  28   static_assert( noexcept(std::bit_width(x)) );
  29
  30   static_assert( std::bit_width(UInt(0)) == 0 );
  31   static_assert( std::bit_width(UInt(1)) == 1 );
  32   static_assert( std::bit_width(UInt(2)) == 2 );
  33   static_assert( std::bit_width(UInt(3)) == 2 );
  34   static_assert( std::bit_width(UInt(4)) == 3 );
  35   static_assert( std::bit_width(UInt(0x11)) == 5 );
  36   static_assert( std::bit_width(UInt(0x20)) == 6 );
  37
  38   if constexpr (std::numeric_limits<UInt>::digits > 8)
  39   {
  40     static_assert( std::bit_width(UInt(0x201)) == 10 );
  41     static_assert( std::bit_width(UInt(0x8ff)) == 12 );
  42     static_assert( std::bit_width(UInt(0x1000)) == 13 );
  43   }
  44
  45   if constexpr (std::numeric_limits<UInt>::digits > 32)
  46   {
  47     static_assert( std::bit_width(UInt(0xabcdef)) == 24 );
  48     static_assert( std::bit_width(UInt(0x1000000)) == 25 );
  49     static_assert( std::bit_width(UInt(0x1000001)) == 25 );
  50   }
  51
  52   if constexpr (std::numeric_limits<UInt>::digits > 64)
  53   {
  54     static_assert( std::bit_width(UInt(1) << 64) == 65 );
  55     static_assert( std::bit_width(UInt(3) << 64) == 66 );
  56   }
  57
  58   return true;
  59 }
  60
  61 static_assert( test( (unsigned char)0 ) );
  62 static_assert( test( (unsigned short)0 ) );
  63 static_assert( test( (unsigned int)0 ) );
  64 static_assert( test( (unsigned long)0 ) );
  65 static_assert( test( (unsigned long long)0 ) );
  66
  67 // std::bit_width(T) shall not participate in overload resolution
  68 // unless T is an unsigned integer type.
  69 struct X { constexpr bool did_not_match() { return true; } };
  70 constexpr X test(...) { return X{}; }
  71 static_assert( test( (bool)0 ).did_not_match() );
  72 static_assert( test( (char)0 ).did_not_match() );
  73 static_assert( test( (int)0 ).did_not_match() );
  74 static_assert( test( (char16_t)0 ).did_not_match() );
  75 static_assert( test( (float)0 ).did_not_match() );
  76 static_assert( test( (void*)0 ).did_not_match() );
  77 static_assert( test( X{} ).did_not_match() );
  78 enum E : unsigned { e };
  79 static_assert( test( e ).did_not_match() );
  80
  81 #if !defined(__STRICT_ANSI__) && defined __SIZEOF_INT128__
  82 static_assert( test( (unsigned __int128)0 ) );
  83 static_assert( test( (__int128)0 ).did_not_match() );
  84 #endif
  85 #if defined(__GLIBCXX_TYPE_INT_N_0)
  86 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_0)0 ) );
  87 static_assert( test( (__GLIBCXX_TYPE_INT_N_0)0 ).did_not_match() );
  88 #endif
  89 #if defined(__GLIBCXX_TYPE_INT_N_1)
  90 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_1)0 ) );
  91 static_assert( test( (__GLIBCXX_TYPE_INT_N_1)0 ).did_not_match() );
  92 #endif
  93 #if defined(__GLIBCXX_TYPE_INT_N_2)
  94 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_2)0 ) );
  95 static_assert( test( (__GLIBCXX_TYPE_INT_N_2)0 ).did_not_match() );
  96 #endif
  97 #if defined(__GLIBCXX_TYPE_INT_N_3)
  98 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_3)0 ) );
  99 static_assert( test( (__GLIBCXX_TYPE_INT_N_3)0 ).did_not_match() );
 100 #endif
 101
 102 #include <cstddef>
 103 static_assert( test( (std::byte)0 ).did_not_match() );