clang/test/CXX/class/class.compare/class.compare.default/p5.cpp

   1 // RUN: %clang_cc1 -std=c++2a -verify %s
   2
   3 // expected-no-diagnostics
   4 namespace std {
   5   struct strong_ordering {
   6     int n;
   7     constexpr operator int() const { return n; }
   8     static const strong_ordering less, equal, greater;
   9   };
  10   constexpr strong_ordering strong_ordering::less{-1}, strong_ordering::equal{0}, strong_ordering::greater{1};
  11 }
  12
  13 // Check that we compare subobjects in the right order.
  14 struct Log {
  15   char buff[10] = {};
  16   int n = 0;
  17   constexpr void add(char c) { buff[n++] = c; }
  18   constexpr bool operator==(const char *p) const { return __builtin_strcmp(p, buff) == 0; }
  19 };
  20
  21 template<char C> struct B {
  22   Log *log;
  23   constexpr bool operator==(const B&) const { log->add(C); return true; }
  24   constexpr std::strong_ordering operator<=>(const B&) const { log->add(C); return {0}; }
  25 };
  26
  27 template<typename T> constexpr bool check(bool which, const char *str) {
  28   Log log;
  29   T c(&log);
  30   (void)(which ? c == c : c <=> c);
  31   return log == str;
  32 }
  33
  34 struct C : B<'a'>, B<'b'> {
  35   B<'r'> r[3];
  36   B<'c'> c;
  37   B<'s'> s[2];
  38   B<'d'> d;
  39
  40   constexpr C(Log *p) : B<'a'>{p}, B<'b'>{p}, r{p, p, p}, c{p}, s{p, p}, d{p} {}
  41
  42   bool operator==(const C&) const = default;
  43   std::strong_ordering operator<=>(const C&) const = default;
  44 };
  45
  46 static_assert(check<C>(false, "abrrrcssd"));
  47 static_assert(check<C>(true, "abrrrcssd"));
  48
  49 struct D {
  50   B<'x'> x;
  51   B<'y'> y[2];
  52
  53   constexpr D(Log *p) : x{p}, y{p, p} {}
  54
  55   bool operator==(const D&) const = default;
  56   std::strong_ordering operator<=>(const D&) const = default;
  57 };
  58
  59 static_assert(check<D>(false, "xyy"));
  60 static_assert(check<D>(true, "xyy"));