libstdc++-v3/testsuite/18_support/comparisons/algorithms/weak_order.cc

   1 // Copyright (C) 2019-2024 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++20 } }
  19
  20 #include <compare>
  21 #include <limits>
  22 #include <testsuite_hooks.h>
  23
  24 using std::weak_order;
  25 using std::weak_ordering;
  26
  27 void
  28 test01()
  29 {
  30   const int one = 1, two = 2;
  31
  32   static_assert( weak_order(one, two) == weak_ordering::less );
  33   static_assert( weak_order(one, one) == weak_ordering::equivalent );
  34   static_assert( weak_order(two, one) == weak_ordering::greater );
  35   static_assert( noexcept(weak_order(1, 1)) );
  36 }
  37
  38 constexpr weak_ordering different_cv_quals(int i, const int j)
  39 {
  40   return weak_order(i, j);
  41 }
  42
  43 void
  44 test02()
  45 {
  46   const int fortytwo = 42, nines = 999, lots = 1000;
  47
  48   static_assert( different_cv_quals(fortytwo, nines) == weak_ordering::less );
  49   static_assert( different_cv_quals(-nines, -nines) == weak_ordering::equivalent );
  50   static_assert( different_cv_quals(-nines, -lots) == weak_ordering::greater );
  51 }
  52
  53 void
  54 test03()
  55 {
  56   constexpr double zero = 0.0;
  57   static_assert( weak_order(zero, zero) == weak_ordering::equivalent );
  58   static_assert( weak_order(-zero, -zero) == weak_ordering::equivalent );
  59   static_assert( weak_order(-zero, zero) == weak_ordering::equivalent );
  60   static_assert( weak_order(zero, -zero) == weak_ordering::equivalent );
  61
  62   constexpr double min = std::numeric_limits<double>::lowest();
  63   constexpr double max = std::numeric_limits<double>::max();
  64   constexpr double nan = std::numeric_limits<double>::quiet_NaN();
  65   constexpr double inf = std::numeric_limits<double>::infinity();
  66   constexpr double denorm = std::numeric_limits<double>::denorm_min();
  67   constexpr double smallest = std::numeric_limits<double>::min();
  68   constexpr double epsilon = std::numeric_limits<double>::epsilon();
  69   static_assert( weak_order(denorm, smallest) == weak_ordering::less );
  70   static_assert( weak_order(denorm, 0.0) == weak_ordering::greater );
  71   // FIXME: these should all use static_assert
  72   VERIFY( weak_order(0.0, nan) == weak_ordering::less );
  73   static_assert( weak_order(nan, nan) == weak_ordering::equivalent );
  74   static_assert( weak_order(nan, -nan) == weak_ordering::greater );
  75   static_assert( weak_order(-nan, nan) == weak_ordering::less );
  76   VERIFY( weak_order(nan, 0.0) == weak_ordering::greater );
  77   VERIFY( weak_order(-nan, 0.0) == weak_ordering::less );
  78   VERIFY( weak_order(-nan, min) == weak_ordering::less );
  79   static_assert( weak_order(-inf, min) == weak_ordering::less );
  80   VERIFY( weak_order(-nan, -inf) == weak_ordering::less );
  81   VERIFY( weak_order(-inf, -nan) == weak_ordering::greater );
  82   static_assert( weak_order(max, inf) == weak_ordering::less );
  83   static_assert( weak_order(inf, max) == weak_ordering::greater );
  84   VERIFY( weak_order(inf, nan) == weak_ordering::less );
  85   static_assert( weak_order(1.0, 1.0+epsilon) == weak_ordering::less );
  86 }
  87
  88 namespace N
  89 {
  90   struct X { int i; };
  91
  92   constexpr weak_ordering operator<=>(X l, X r)
  93   {
  94     if (l.i < 0 && r.i < 0)
  95       return weak_ordering::equivalent;
  96     return r.i <=> l.i;
  97   }
  98
  99   constexpr bool operator==(X l, X r) { return std::is_eq(l <=> r); }
 100
 101   static_assert(std::three_way_comparable<X>);
 102 }
 103
 104 void
 105 test04()
 106 {
 107   using N::X;
 108   X one{1};
 109   X negone{-1};
 110
 111   // FIXME: these should all use static_assert
 112   VERIFY( weak_order(one, X{1}) == weak_ordering::equivalent );
 113   VERIFY( weak_order(negone, X{-2}) == weak_ordering::equivalent );
 114   VERIFY( weak_order(one, X{2}) == weak_ordering::greater );
 115   static_assert( !noexcept(weak_order(X{1}, X{2})) );
 116 }
 117
 118 int main()
 119 {
 120   test01();
 121   test02();
 122   test03();
 123   test04();
 124 }