llvm-project/clang/test/SemaCXX/libstdcxx_libcxx_less_hack.cpp

68 lines
1.9 KiB
C++

// This is a test for a hack in Clang that works around a problem introduced by
// DR583: it's no longer possible to compare a pointer against nullptr_t, but
// we still want to permit those comparisons within less<> and friends.
// RUN: %clang_cc1 -verify %s -std=c++14
namespace std {
template<typename T = void> struct less {};
template<typename T = void> struct less_equal {};
template<typename T = void> struct greater {};
template<typename T = void> struct greater_equal {};
template<> struct less<> {
template <class T1, class T2>
auto operator()(T1 &&t, T2 &&u) const noexcept(noexcept(t < u))
-> decltype(t < u) {
return t < u;
}
};
template<> struct less_equal<> {
template <class T1, class T2>
auto operator()(T1 &&t, T2 &&u) const noexcept(noexcept(t <= u))
-> decltype(t <= u) {
return t <= u;
}
};
template<> struct greater<> {
template <class T1, class T2>
auto operator()(T1 &&t, T2 &&u) const noexcept(noexcept(t > u))
-> decltype(t > u) {
return t > u;
}
};
template<> struct greater_equal<> {
template <class T1, class T2>
auto operator()(T1 &&t, T2 &&u) const noexcept(noexcept(t >= u))
-> decltype(t >= u) {
return t >= u;
}
};
template<typename = void> struct unrelated;
template<> struct unrelated<> {
template <class T1, class T2>
auto operator()(T1 &&t, T2 &&u) const noexcept(noexcept(t < u)) // expected-note {{substitution failure}}
-> decltype(t < u) {
return t < u;
}
};
};
void test(int *p) {
using namespace std;
less<>()(p, nullptr);
less<>()(nullptr, p);
less_equal<>()(p, nullptr);
less_equal<>()(nullptr, p);
greater<>()(p, nullptr);
greater<>()(nullptr, p);
greater_equal<>()(p, nullptr);
greater_equal<>()(nullptr, p);
unrelated<>()(p, nullptr); // expected-error {{no matching function}}
}