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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
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
// template<class U = T>
// constexpr explicit(!is_convertible_v<U, T>) expected(U&& v);
//
// Constraints:
// - is_same_v<remove_cvref_t<U>, in_place_t> is false; and
// - is_same_v<expected, remove_cvref_t<U>> is false; and
// - remove_cvref_t<U> is not a specialization of unexpected; and
// - is_constructible_v<T, U> is true.
//
// Effects: Direct-non-list-initializes val with std::forward<U>(v).
//
// Postconditions: has_value() is true.
//
// Throws: Any exception thrown by the initialization of val.
#include <cassert>
#include <expected>
#include <type_traits>
#include <utility>
#include "MoveOnly.h"
#include "test_macros.h"
// Test Constraints:
static_assert(std::is_constructible_v<std::expected<int, int>, int>);
// is_same_v<remove_cvref_t<U>, in_place_t>
struct FromJustInplace {
FromJustInplace(std::in_place_t);
};
static_assert(!std::is_constructible_v<std::expected<FromJustInplace, int>, std::in_place_t>);
static_assert(!std::is_constructible_v<std::expected<FromJustInplace, int>, std::in_place_t const&>);
// is_same_v<expected, remove_cvref_t<U>>
// Note that result is true because it is covered by the constructors that take expected
static_assert(std::is_constructible_v<std::expected<int, int>, std::expected<int, int>&>);
// remove_cvref_t<U> is a specialization of unexpected
// Note that result is true because it is covered by the constructors that take unexpected
static_assert(std::is_constructible_v<std::expected<int, int>, std::unexpected<int>&>);
// !is_constructible_v<T, U>
struct foo {};
static_assert(!std::is_constructible_v<std::expected<int, int>, foo>);
// test explicit(!is_convertible_v<U, T>)
struct NotConvertible {
explicit NotConvertible(int);
};
static_assert(std::is_convertible_v<int, std::expected<int, int>>);
static_assert(!std::is_convertible_v<int, std::expected<NotConvertible, int>>);
struct CopyOnly {
int i;
constexpr CopyOnly(int ii) : i(ii) {}
CopyOnly(const CopyOnly&) = default;
CopyOnly(CopyOnly&&) = delete;
friend constexpr bool operator==(const CopyOnly& mi, int ii) { return mi.i == ii; }
};
template <class T>
constexpr void testInt() {
std::expected<T, int> e(5);
assert(e.has_value());
assert(e.value() == 5);
}
template <class T>
constexpr void testLValue() {
T t(5);
std::expected<T, int> e(t);
assert(e.has_value());
assert(e.value() == 5);
}
template <class T>
constexpr void testRValue() {
std::expected<T, int> e(T(5));
assert(e.has_value());
assert(e.value() == 5);
}
constexpr bool test() {
testInt<int>();
testInt<CopyOnly>();
testInt<MoveOnly>();
testLValue<int>();
testLValue<CopyOnly>();
testRValue<int>();
testRValue<MoveOnly>();
// Test default template argument.
// Without it, the template parameter cannot be deduced from an initializer list
{
struct Bar {
int i;
int j;
constexpr Bar(int ii, int jj) : i(ii), j(jj) {}
};
std::expected<Bar, int> e({5, 6});
assert(e.value().i == 5);
assert(e.value().j == 6);
}
// this is a confusing example, but the behaviour
// is exactly what is specified in the spec
// see https://cplusplus.github.io/LWG/issue3836
{
struct BaseError {};
struct DerivedError : BaseError {};
std::expected<bool, DerivedError> e1(false);
std::expected<bool, BaseError> e2(e1);
assert(e2.has_value());
assert(e2.value()); // yes, e2 holds "true"
}
return true;
}
void testException() {
#ifndef TEST_HAS_NO_EXCEPTIONS
struct Except {};
struct Throwing {
Throwing(int) { throw Except{}; };
};
try {
std::expected<Throwing, int> u(5);
assert(false);
} catch (Except) {
}
#endif // TEST_HAS_NO_EXCEPTIONS
}
int main(int, char**) {
test();
static_assert(test());
testException();
return 0;
}
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