libstdc++-v3/testsuite/26_numerics/gcd/2.cc

   1 // Copyright (C) 2015-2024 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 run { target c++17 } }
  19
  20 #include <numeric>
  21 #include <climits>
  22 #include <testsuite_hooks.h>
  23
  24 constexpr struct testcase { unsigned long long p, q, r; } testcases[] = {
  25   { 5, 8, 1 },
  26   { 6, 35, 1 },
  27   { 30, 42, 6 },
  28   { 24, 60, 12 },
  29   { 55, 144, 1 },
  30   { 105, 252, 21 },
  31   { 253, 22121, 11 },
  32   { 1386, 3213, 63 },
  33   { 2028, 2049, 3 },
  34   { 46391, 62527, 2017 },
  35   { 63245986, 39088169, 1 },
  36   { 77160074263, 47687519812, 1 },
  37   { 77160074264, 47687519812, 4 },
  38 };
  39
  40 template<typename P, typename Q>
  41 constexpr bool
  42 check(P p, Q q, unsigned long long r)
  43 {
  44   using R = std::common_type_t<P, Q>;
  45   static_assert( std::is_same_v<decltype(std::gcd(p, q)), R> );
  46   static_assert( std::is_same_v<decltype(std::gcd(q, p)), R> );
  47   R r1 = std::gcd(p, q);
  48   // Check non-negative, so conversion to unsigned long doesn't alter value.
  49   VERIFY( r1 >= 0 );
  50   // Check for expected result
  51   VERIFY( (unsigned long long)r1 == r );
  52   // Check reversing arguments doesn't change result
  53   VERIFY( std::gcd(q, p) == r1 );
  54
  55   P pabs = p < 0 ? -p : p;
  56   VERIFY( std::gcd(p, p) == pabs );
  57   VERIFY( std::gcd(0, p) == pabs );
  58   VERIFY( std::gcd(p, 0) == pabs );
  59   VERIFY( std::gcd(1, p) == 1 );
  60   VERIFY( std::gcd(p, 1) == 1 );
  61   Q qabs = q < 0 ? -q : q;
  62   VERIFY( std::gcd(q, q) == qabs );
  63   VERIFY( std::gcd(0, q) == qabs );
  64   VERIFY( std::gcd(q, 0) == qabs );
  65   VERIFY( std::gcd(1, q) == 1 );
  66   VERIFY( std::gcd(q, 1) == 1 );
  67   VERIFY( std::gcd(r, r) == r );
  68   VERIFY( std::gcd(0, r) == r );
  69   VERIFY( std::gcd(r, 0) == r );
  70   VERIFY( std::gcd(1, r) == 1 );
  71   VERIFY( std::gcd(r, 1) == 1 );
  72
  73   return true;
  74 }
  75
  76 constexpr bool
  77 test01()
  78 {
  79   for (auto t : testcases)
  80   {
  81     check(t.p, t.q, t.r);
  82
  83     if (t.p <= LONG_MAX && t.q <= LONG_MAX)
  84     {
  85       check( (long)t.p,  (long)t.p, t.p);
  86       check(-(long)t.p,  (long)t.p, t.p);
  87       check(-(long)t.p, -(long)t.p, t.p);
  88
  89       check( (long)t.p, t.q, t.r);
  90       check(-(long)t.p, t.q, t.r);
  91
  92       check(t.p,  (long)t.q, t.r);
  93       check(t.p, -(long)t.q, t.r);
  94
  95       check( (long)t.p,  (long)t.q, t.r);
  96       check( (long)t.p, -(long)t.q, t.r);
  97       check(-(long)t.p,  (long)t.q, t.r);
  98       check(-(long)t.p, -(long)t.q, t.r);
  99     }
 100
 101     if (t.p <= INT_MAX && t.q <= INT_MAX)
 102     {
 103       check((long)t.p,  (int)t.q, t.r);
 104       check(-(int)t.p, (long)t.q, t.r);
 105
 106       check( (int)t.p, (unsigned)t.q, t.r);
 107       check(-(int)t.p, (unsigned)t.q, t.r);
 108
 109       check(-(int)t.p,  -(int)t.q, t.r);
 110       check(-(int)t.p, -(long)t.q, t.r);
 111     }
 112
 113     if (t.p <= SHRT_MAX && t.q <= SHRT_MAX)
 114     {
 115       check(  (long)t.p, (short)t.q, t.r);
 116       check(-(short)t.p,  (long)t.q, t.r);
 117
 118       check( (short)t.p, (unsigned short)t.q, t.r);
 119       check(-(short)t.p, (unsigned short)t.q, t.r);
 120
 121       check(-(short)t.p, -(short)t.q, t.r);
 122       check(-(short)t.p,  -(long)t.q, t.r);
 123     }
 124   }
 125   return true;
 126 }
 127
 128
 129 int main()
 130 {
 131   static_assert( test01() );  // constexpr
 132   VERIFY( test01() );         // non-constexpr
 133 }