61 lines · cpp
1// RUN: %clang_cc1 -std=c++2a -verify %s2 3// expected-no-diagnostics4namespace 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.14struct 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 21template<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 27template<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 34struct 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 46static_assert(check<C>(false, "abrrrcssd"));47static_assert(check<C>(true, "abrrrcssd"));48 49struct 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 59static_assert(check<D>(false, "xyy"));60static_assert(check<D>(true, "xyy"));61