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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 G>
// constexpr expected& operator=(const unexpected<G>& e);
//
// Let GF be const G&
// Constraints:
// - is_constructible_v<E, GF> is true; and
// - is_assignable_v<E&, GF> is true; and
// - is_nothrow_constructible_v<E, GF> || is_nothrow_move_constructible_v<T> ||
// is_nothrow_move_constructible_v<E> is true.
//
// Effects:
// - If has_value() is true, equivalent to:
// reinit-expected(unex, val, std::forward<GF>(e.error()));
// has_val = false;
// - Otherwise, equivalent to: unex = std::forward<GF>(e.error());
// Returns: *this.
#include <cassert>
#include <concepts>
#include <expected>
#include <type_traits>
#include <utility>
#include "../../types.h"
#include "test_macros.h"
struct NotCopyConstructible {
NotCopyConstructible(const NotCopyConstructible&) = delete;
NotCopyConstructible& operator=(const NotCopyConstructible&) = default;
};
struct NotCopyAssignable {
NotCopyAssignable(const NotCopyAssignable&) = default;
NotCopyAssignable& operator=(const NotCopyAssignable&) = delete;
};
struct MoveMayThrow {
MoveMayThrow(MoveMayThrow const&) = default;
MoveMayThrow& operator=(const MoveMayThrow&) = default;
MoveMayThrow(MoveMayThrow&&) noexcept(false) {}
MoveMayThrow& operator=(MoveMayThrow&&) noexcept(false) { return *this; }
};
// Test constraints
static_assert(std::is_assignable_v<std::expected<int, int>&, const std::unexpected<int>&>);
// !is_constructible_v<E, GF>
static_assert(
!std::is_assignable_v<std::expected<int, NotCopyConstructible>&, const std::unexpected<NotCopyConstructible>&>);
// !is_assignable_v<E&, GF>
static_assert(!std::is_assignable_v<std::expected<int, NotCopyAssignable>&, const std::unexpected<NotCopyAssignable>&>);
template <bool moveNoexcept, bool convertNoexcept>
struct MaybeNoexcept {
explicit MaybeNoexcept(int) noexcept(convertNoexcept);
MaybeNoexcept(MaybeNoexcept&&) noexcept(moveNoexcept);
MaybeNoexcept& operator=(MaybeNoexcept&&) = default;
MaybeNoexcept& operator=(int);
};
// !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
// is_nothrow_move_constructible_v<E>
static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<true, false>>&,
const std::unexpected<int>&>);
// is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
// !is_nothrow_move_constructible_v<E>
static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, true>>&,
const std::unexpected<int>&>);
// !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<T> &&
// !is_nothrow_move_constructible_v<E>
static_assert(std::is_assignable_v<std::expected<MaybeNoexcept<true, true>, MaybeNoexcept<false, false>>&,
const std::unexpected<int>&>);
// !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<T> &&
// !is_nothrow_move_constructible_v<E>
static_assert(!std::is_assignable_v<std::expected<MaybeNoexcept<false, false>, MaybeNoexcept<false, false>>&,
const std::unexpected<int>&>);
constexpr bool test() {
// - If has_value() is true, equivalent to:
// reinit-expected(unex, val, std::forward<GF>(e.error()));
// is_nothrow_constructible_v<E, GF>
//
// In this case, it should call the branch
// destroy_at(addressof(oldval));
// construct_at(addressof(newval), std::forward<Args>(args)...);
{
BothNoexcept::state oldState{};
std::expected<BothNoexcept, BothNoexcept> e(std::in_place, oldState, 5);
const std::unexpected<int> un(10);
decltype(auto) x = (e = un);
static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothNoexcept>&>);
assert(&x == &e);
assert(!oldState.moveCtorCalled);
assert(oldState.dtorCalled);
assert(e.error().copiedFromInt);
}
// - If has_value() is true, equivalent to:
// reinit-expected(unex, val, std::forward<GF>(e.error()));
// !is_nothrow_constructible_v<E, GF> && is_nothrow_move_constructible_v<E>
//
// In this case, it should call the branch
// T tmp(std::forward<Args>(args)...);
// destroy_at(addressof(oldval));
// construct_at(addressof(newval), std::move(tmp));
{
BothNoexcept::state oldState{};
std::expected<BothNoexcept, MoveNoexceptConvThrow> e(std::in_place, oldState, 5);
const std::unexpected<int> un(10);
decltype(auto) x = (e = un);
static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, MoveNoexceptConvThrow>&>);
assert(&x == &e);
assert(!oldState.moveCtorCalled);
assert(oldState.dtorCalled);
assert(!e.error().copiedFromInt);
assert(e.error().movedFromTmp);
}
// - If has_value() is true, equivalent to:
// reinit-expected(unex, val, std::forward<GF>(e.error()));
// !is_nothrow_constructible_v<E, GF> && !is_nothrow_move_constructible_v<E>
// is_nothrow_move_constructible_v<T>
//
// In this case, it should call the branch
// U tmp(std::move(oldval));
// destroy_at(addressof(oldval));
// try {
// construct_at(addressof(newval), std::forward<Args>(args)...);
// } catch (...) {
// construct_at(addressof(oldval), std::move(tmp));
// throw;
// }
{
BothNoexcept::state oldState{};
std::expected<BothNoexcept, BothMayThrow> e(std::in_place, oldState, 5);
const std::unexpected<int> un(10);
decltype(auto) x = (e = un);
static_assert(std::same_as<decltype(x), std::expected<BothNoexcept, BothMayThrow>&>);
assert(&x == &e);
assert(oldState.moveCtorCalled);
assert(oldState.dtorCalled);
assert(e.error().copiedFromInt);
}
// Otherwise, equivalent to: unex = std::forward<GF>(e.error());
{
Traced::state oldState{};
Traced::state newState{};
std::expected<int, Traced> e1(std::unexpect, oldState, 5);
const std::unexpected<Traced> e(std::in_place, newState, 10);
decltype(auto) x = (e1 = e);
static_assert(std::same_as<decltype(x), std::expected<int, Traced>&>);
assert(&x == &e1);
assert(!e1.has_value());
assert(e1.error().data_ == 10);
assert(oldState.copyAssignCalled);
}
return true;
}
void testException() {
#ifndef TEST_HAS_NO_EXCEPTIONS
std::expected<int, ThrowOnConvert> e1(std::in_place, 5);
const std::unexpected<int> un(10);
try {
e1 = un;
assert(false);
} catch (Except) {
assert(e1.has_value());
assert(*e1 == 5);
}
#endif // TEST_HAS_NO_EXCEPTIONS
}
int main(int, char**) {
test();
static_assert(test());
testException();
return 0;
}
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