default.pass.cpp
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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <tuple>
// template <class... Types> class tuple;
// explicit(see-below) constexpr tuple();
// UNSUPPORTED: c++03
#include <tuple>
#include <string>
#include <cassert>
#include <type_traits>
#include "test_macros.h"
#include "DefaultOnly.h"
struct NoDefault {
NoDefault() = delete;
explicit NoDefault(int) { }
};
struct NoExceptDefault {
NoExceptDefault() noexcept = default;
};
struct ThrowingDefault {
ThrowingDefault() { }
};
struct IllFormedDefault {
IllFormedDefault(int x) : value(x) {}
template <bool Pred = false>
constexpr IllFormedDefault() {
static_assert(Pred,
"The default constructor should not be instantiated");
}
int value;
};
int main(int, char**)
{
{
std::tuple<> t;
(void)t;
}
{
std::tuple<int> t;
assert(std::get<0>(t) == 0);
}
{
std::tuple<int, char*> t;
assert(std::get<0>(t) == 0);
assert(std::get<1>(t) == nullptr);
}
{
std::tuple<int, char*, std::string> t;
assert(std::get<0>(t) == 0);
assert(std::get<1>(t) == nullptr);
assert(std::get<2>(t) == "");
}
{
std::tuple<int, char*, std::string, DefaultOnly> t;
assert(std::get<0>(t) == 0);
assert(std::get<1>(t) == nullptr);
assert(std::get<2>(t) == "");
assert(std::get<3>(t) == DefaultOnly());
}
{
// See bug #21157.
static_assert(!std::is_default_constructible<std::tuple<NoDefault>>(), "");
static_assert(!std::is_default_constructible<std::tuple<DefaultOnly, NoDefault>>(), "");
static_assert(!std::is_default_constructible<std::tuple<NoDefault, DefaultOnly, NoDefault>>(), "");
}
{
static_assert(noexcept(std::tuple<NoExceptDefault>()), "");
static_assert(noexcept(std::tuple<NoExceptDefault, NoExceptDefault>()), "");
static_assert(!noexcept(std::tuple<ThrowingDefault, NoExceptDefault>()), "");
static_assert(!noexcept(std::tuple<NoExceptDefault, ThrowingDefault>()), "");
static_assert(!noexcept(std::tuple<ThrowingDefault, ThrowingDefault>()), "");
}
{
constexpr std::tuple<> t;
(void)t;
}
{
constexpr std::tuple<int> t;
assert(std::get<0>(t) == 0);
}
{
constexpr std::tuple<int, char*> t;
assert(std::get<0>(t) == 0);
assert(std::get<1>(t) == nullptr);
}
{
// Check that the SFINAE on the default constructor is not evaluated when
// it isn't needed. If the default constructor is evaluated then this test
// should fail to compile.
IllFormedDefault v(0);
std::tuple<IllFormedDefault> t(v);
}
{
struct Base { };
struct Derived : Base { protected: Derived() = default; };
static_assert(!std::is_default_constructible<std::tuple<Derived, int> >::value, "");
}
return 0;
}