/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <folly/Optional.h>
#include <algorithm>
#include <initializer_list>
#include <iomanip>
#include <memory>
#include <optional>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <vector>
#include <folly/CppAttributes.h>
#include <folly/Portability.h>
#include <folly/portability/GMock.h>
#include <folly/portability/GTest.h>
using std::shared_ptr;
using std::unique_ptr;
namespace {
struct HashableStruct {};
struct UnhashableStruct {};
} // namespace
namespace std {
template <>
struct hash<HashableStruct> {
[[maybe_unused]] size_t operator()(const HashableStruct&) const noexcept {
return 0;
}
};
} // namespace std
namespace folly {
namespace {
template <class V>
std::ostream& operator<<(std::ostream& os, const Optional<V>& v) {
if (v) {
os << "Optional(" << v.value() << ')';
} else {
os << "None";
}
return os;
}
struct NoDefault {
NoDefault(int, int) {}
char a, b, c;
};
} // namespace
static_assert(sizeof(Optional<char>) == 2, "");
static_assert(sizeof(Optional<int>) == 8, "");
static_assert(sizeof(Optional<NoDefault>) == 4, "");
static_assert(sizeof(Optional<char>) == sizeof(std::optional<char>), "");
static_assert(sizeof(Optional<short>) == sizeof(std::optional<short>), "");
static_assert(sizeof(Optional<int>) == sizeof(std::optional<int>), "");
static_assert(sizeof(Optional<double>) == sizeof(std::optional<double>), "");
static_assert(is_hashable_v<folly::Optional<HashableStruct>>);
static_assert(!is_hashable_v<folly::Optional<UnhashableStruct>>);
TEST(Optional, ConstexprConstructible) {
// Use FOLLY_STORAGE_CONSTEXPR to work around MSVC not taking this.
static FOLLY_STORAGE_CONSTEXPR Optional<int> opt;
// NOTE: writing `opt = none` instead of `opt(none)` causes gcc to reject this
// code, claiming that the (non-constexpr) move ctor of `Optional` is being
// invoked.
static FOLLY_STORAGE_CONSTEXPR Optional<int> opt2(none);
EXPECT_FALSE(opt.has_value());
EXPECT_FALSE(opt2.has_value());
}
TEST(Optional, NoDefault) {
Optional<NoDefault> x;
EXPECT_FALSE(x);
x.emplace(4, 5);
EXPECT_TRUE(bool(x));
x.reset();
EXPECT_FALSE(x);
}
TEST(Optional, Emplace) {
Optional<std::vector<int>> opt;
auto& values1 = opt.emplace(3, 4);
EXPECT_THAT(values1, testing::ElementsAre(4, 4, 4));
auto& values2 = opt.emplace(2, 5);
EXPECT_THAT(values2, testing::ElementsAre(5, 5));
}
TEST(Optional, EmplaceInitializerList) {
Optional<std::vector<int>> opt;
auto& values1 = opt.emplace({3, 4, 5});
EXPECT_THAT(values1, testing::ElementsAre(3, 4, 5));
auto& values2 = opt.emplace({4, 5, 6});
EXPECT_THAT(values2, testing::ElementsAre(4, 5, 6));
}
TEST(Optional, Reset) {
Optional<int> opt(3);
opt.reset();
EXPECT_FALSE(opt);
}
TEST(Optional, String) {
Optional<std::string> maybeString;
EXPECT_FALSE(maybeString);
maybeString = "hello";
EXPECT_TRUE(bool(maybeString));
}
TEST(Optional, Const) {
{ // default construct
Optional<const int> opt;
EXPECT_FALSE(bool(opt));
opt.emplace(4);
EXPECT_EQ(*opt, 4);
opt.emplace(5);
EXPECT_EQ(*opt, 5);
opt.reset();
EXPECT_FALSE(bool(opt));
}
{ // copy-constructed
const int x = 6;
Optional<const int> opt(x);
EXPECT_EQ(*opt, 6);
}
{ // move-constructed
const int x = 7;
Optional<const int> opt(std::move(x));
EXPECT_EQ(*opt, 7);
}
// no assignment allowed
}
TEST(Optional, Simple) {
Optional<int> opt;
EXPECT_FALSE(bool(opt));
EXPECT_EQ(42, opt.value_or(42));
opt = 4;
EXPECT_TRUE(bool(opt));
EXPECT_EQ(4, *opt);
EXPECT_EQ(4, opt.value_or(42));
opt = 5;
EXPECT_EQ(5, *opt);
opt.reset();
EXPECT_FALSE(bool(opt));
}
namespace {
class MoveTester {
public:
/* implicit */ MoveTester(const char* s) : s_(s) {}
MoveTester(const MoveTester&) = default;
MoveTester(MoveTester&& other) noexcept {
s_ = std::move(other.s_);
other.s_ = "";
}
MoveTester& operator=(const MoveTester&) = default;
MoveTester& operator=(MoveTester&& other) noexcept {
s_ = std::move(other.s_);
other.s_ = "";
return *this;
}
private:
friend bool operator==(const MoveTester& o1, const MoveTester& o2);
std::string s_;
};
bool operator==(const MoveTester& o1, const MoveTester& o2) {
return o1.s_ == o2.s_;
}
} // namespace
TEST(Optional, valueOrRvalueArg) {
Optional<MoveTester> opt;
MoveTester dflt = "hello";
EXPECT_EQ("hello", opt.value_or(dflt));
EXPECT_EQ("hello", dflt);
EXPECT_EQ("hello", opt.value_or(std::move(dflt)));
EXPECT_EQ("", dflt);
EXPECT_EQ("world", opt.value_or("world"));
dflt = "hello";
// Make sure that the const overload works on const objects
const auto& optc = opt;
EXPECT_EQ("hello", optc.value_or(dflt));
EXPECT_EQ("hello", dflt);
EXPECT_EQ("hello", optc.value_or(std::move(dflt)));
EXPECT_EQ("", dflt);
EXPECT_EQ("world", optc.value_or("world"));
dflt = "hello";
opt = "meow";
EXPECT_EQ("meow", opt.value_or(dflt));
EXPECT_EQ("hello", dflt);
EXPECT_EQ("meow", opt.value_or(std::move(dflt)));
EXPECT_EQ("hello", dflt); // only moved if used
}
TEST(Optional, valueOrNoncopyable) {
Optional<std::unique_ptr<int>> opt;
std::unique_ptr<int> dflt(new int(42));
EXPECT_EQ(42, *std::move(opt).value_or(std::move(dflt)));
}
struct ExpectingDeleter {
explicit ExpectingDeleter(int expected_) : expected(expected_) {}
int expected;
void operator()(const int* ptr) {
EXPECT_EQ(*ptr, expected);
delete ptr;
}
};
TEST(Optional, valueMove) {
auto ptr = Optional<std::unique_ptr<int, ExpectingDeleter>>(
{new int(42), ExpectingDeleter{1337}})
.value();
*ptr = 1337;
}
TEST(Optional, dereferenceMove) {
auto ptr = *Optional<std::unique_ptr<int, ExpectingDeleter>>(
{new int(42), ExpectingDeleter{1337}});
*ptr = 1337;
}
TEST(Optional, EmptyConstruct) {
Optional<int> opt;
EXPECT_FALSE(bool(opt));
Optional<int> test1(opt);
EXPECT_FALSE(bool(test1));
Optional<int> test2(std::move(opt));
EXPECT_FALSE(bool(test2));
}
TEST(Optional, InPlaceConstruct) {
using A = std::pair<int, double>;
Optional<A> opt(std::in_place, 5, 3.2);
EXPECT_TRUE(bool(opt));
EXPECT_EQ(5, opt->first);
}
TEST(Optional, InPlaceNestedConstruct) {
using A = std::pair<int, double>;
Optional<Optional<A>> opt(std::in_place, std::in_place, 5, 3.2);
EXPECT_TRUE(bool(opt));
EXPECT_TRUE(bool(*opt));
EXPECT_EQ(5, (*opt)->first);
}
TEST(Optional, Unique) {
Optional<unique_ptr<int>> opt;
opt.reset();
EXPECT_FALSE(bool(opt));
// empty->emplaced
opt.emplace(new int(5));
EXPECT_TRUE(bool(opt));
EXPECT_EQ(5, **opt);
opt.reset();
// empty->moved
opt = std::make_unique<int>(6);
EXPECT_EQ(6, **opt);
// full->moved
opt = std::make_unique<int>(7);
EXPECT_EQ(7, **opt);
// move it out by move construct
Optional<unique_ptr<int>> moved(std::move(opt));
EXPECT_TRUE(bool(moved));
EXPECT_FALSE(bool(opt));
EXPECT_EQ(7, **moved);
EXPECT_TRUE(bool(moved));
opt = std::move(moved); // move it back by move assign
EXPECT_FALSE(bool(moved));
EXPECT_TRUE(bool(opt));
EXPECT_EQ(7, **opt);
}
TEST(Optional, Shared) {
shared_ptr<int> ptr;
Optional<shared_ptr<int>> opt;
EXPECT_FALSE(bool(opt));
// empty->emplaced
opt.emplace(new int(5));
EXPECT_TRUE(bool(opt));
ptr = opt.value();
EXPECT_EQ(ptr.get(), opt->get());
EXPECT_EQ(2, ptr.use_count());
opt.reset();
EXPECT_EQ(1, ptr.use_count());
// full->copied
opt = ptr;
EXPECT_EQ(2, ptr.use_count());
EXPECT_EQ(ptr.get(), opt->get());
opt.reset();
EXPECT_EQ(1, ptr.use_count());
// full->moved
opt = std::move(ptr);
EXPECT_EQ(1, opt->use_count());
EXPECT_EQ(nullptr, ptr.get());
{
Optional<shared_ptr<int>> copied(opt);
EXPECT_EQ(2, opt->use_count());
Optional<shared_ptr<int>> moved(std::move(opt));
EXPECT_EQ(2, moved->use_count());
moved.emplace(new int(6));
EXPECT_EQ(1, moved->use_count());
copied = moved;
EXPECT_EQ(2, moved->use_count());
}
}
TEST(Optional, Order) {
std::vector<Optional<int>> vect{
{none},
{3},
{1},
{none},
{2},
};
std::vector<Optional<int>> expected{
{none},
{none},
{1},
{2},
{3},
};
std::sort(vect.begin(), vect.end());
EXPECT_EQ(vect, expected);
}
TEST(Optional, Swap) {
Optional<std::string> a;
Optional<std::string> b;
swap(a, b);
EXPECT_FALSE(a.has_value());
EXPECT_FALSE(b.has_value());
a = "hello";
EXPECT_TRUE(a.has_value());
EXPECT_FALSE(b.has_value());
EXPECT_EQ("hello", a.value());
swap(a, b);
EXPECT_FALSE(a.has_value());
EXPECT_TRUE(b.has_value());
EXPECT_EQ("hello", b.value());
a = "bye";
EXPECT_TRUE(a.has_value());
EXPECT_EQ("bye", a.value());
swap(a, b);
EXPECT_TRUE(a.has_value());
EXPECT_TRUE(b.has_value());
EXPECT_EQ("hello", a.value());
EXPECT_EQ("bye", b.value());
}
TEST(Optional, Comparisons) {
Optional<int> o_;
Optional<int> o1(1);
Optional<int> o2(2);
EXPECT_TRUE(o_ <= (o_));
EXPECT_TRUE(o_ == (o_));
EXPECT_TRUE(o_ >= (o_));
EXPECT_TRUE(o1 < o2);
EXPECT_TRUE(o1 <= o2);
EXPECT_TRUE(o1 <= (o1));
EXPECT_TRUE(o1 == (o1));
EXPECT_TRUE(o1 != o2);
EXPECT_TRUE(o1 >= (o1));
EXPECT_TRUE(o2 >= o1);
EXPECT_TRUE(o2 > o1);
EXPECT_FALSE(o2 < o1);
EXPECT_FALSE(o2 <= o1);
EXPECT_FALSE(o2 <= o1);
EXPECT_FALSE(o2 == o1);
EXPECT_FALSE(o1 != (o1));
EXPECT_FALSE(o1 >= o2);
EXPECT_FALSE(o1 >= o2);
EXPECT_FALSE(o1 > o2);
/* folly::Optional explicitly doesn't support comparisons with contained value
EXPECT_TRUE(1 < o2);
EXPECT_TRUE(1 <= o2);
EXPECT_TRUE(1 <= o1);
EXPECT_TRUE(1 == o1);
EXPECT_TRUE(2 != o1);
EXPECT_TRUE(1 >= o1);
EXPECT_TRUE(2 >= o1);
EXPECT_TRUE(2 > o1);
EXPECT_FALSE(o2 < 1);
EXPECT_FALSE(o2 <= 1);
EXPECT_FALSE(o2 <= 1);
EXPECT_FALSE(o2 == 1);
EXPECT_FALSE(o2 != 2);
EXPECT_FALSE(o1 >= 2);
EXPECT_FALSE(o1 >= 2);
EXPECT_FALSE(o1 > 2);
*/
// std::optional does support comparison with contained value, which can
// lead to confusion when a bool is contained
std::optional<int> boi(3);
EXPECT_TRUE(boi < 5);
EXPECT_TRUE(boi <= 4);
EXPECT_TRUE(boi == 3);
EXPECT_TRUE(boi != 2);
EXPECT_TRUE(boi >= 1);
EXPECT_TRUE(boi > 0);
EXPECT_TRUE(1 < boi);
EXPECT_TRUE(2 <= boi);
EXPECT_TRUE(3 == boi);
EXPECT_TRUE(4 != boi);
EXPECT_TRUE(5 >= boi);
EXPECT_TRUE(6 > boi);
std::optional<bool> bob(false);
EXPECT_TRUE((bool)bob);
EXPECT_TRUE(bob == false); // well that was confusing
EXPECT_FALSE(bob != false);
}
TEST(Optional, HeterogeneousComparisons) {
using opt8 = Optional<uint8_t>;
using opt64 = Optional<uint64_t>;
EXPECT_TRUE(opt8(4) == uint64_t(4));
EXPECT_FALSE(opt8(8) == uint64_t(4));
EXPECT_FALSE(opt8() == uint64_t(4));
EXPECT_TRUE(uint64_t(4) == opt8(4));
EXPECT_FALSE(uint64_t(4) == opt8(8));
EXPECT_FALSE(uint64_t(4) == opt8());
EXPECT_FALSE(opt8(4) != uint64_t(4));
EXPECT_TRUE(opt8(8) != uint64_t(4));
EXPECT_TRUE(opt8() != uint64_t(4));
EXPECT_FALSE(uint64_t(4) != opt8(4));
EXPECT_TRUE(uint64_t(4) != opt8(8));
EXPECT_TRUE(uint64_t(4) != opt8());
EXPECT_TRUE(opt8() == opt64());
EXPECT_TRUE(opt8(4) == opt64(4));
EXPECT_FALSE(opt8(8) == opt64(4));
EXPECT_FALSE(opt8() == opt64(4));
EXPECT_FALSE(opt8(4) == opt64());
EXPECT_FALSE(opt8() != opt64());
EXPECT_FALSE(opt8(4) != opt64(4));
EXPECT_TRUE(opt8(8) != opt64(4));
EXPECT_TRUE(opt8() != opt64(4));
EXPECT_TRUE(opt8(4) != opt64());
EXPECT_TRUE(opt8() < opt64(4));
EXPECT_TRUE(opt8(4) < opt64(8));
EXPECT_FALSE(opt8() < opt64());
EXPECT_FALSE(opt8(4) < opt64(4));
EXPECT_FALSE(opt8(8) < opt64(4));
EXPECT_FALSE(opt8(4) < opt64());
EXPECT_FALSE(opt8() > opt64(4));
EXPECT_FALSE(opt8(4) > opt64(8));
EXPECT_FALSE(opt8() > opt64());
EXPECT_FALSE(opt8(4) > opt64(4));
EXPECT_TRUE(opt8(8) > opt64(4));
EXPECT_TRUE(opt8(4) > opt64());
EXPECT_TRUE(opt8() <= opt64(4));
EXPECT_TRUE(opt8(4) <= opt64(8));
EXPECT_TRUE(opt8() <= opt64());
EXPECT_TRUE(opt8(4) <= opt64(4));
EXPECT_FALSE(opt8(8) <= opt64(4));
EXPECT_FALSE(opt8(4) <= opt64());
EXPECT_FALSE(opt8() >= opt64(4));
EXPECT_FALSE(opt8(4) >= opt64(8));
EXPECT_TRUE(opt8() >= opt64());
EXPECT_TRUE(opt8(4) >= opt64(4));
EXPECT_TRUE(opt8(8) >= opt64(4));
EXPECT_TRUE(opt8(4) >= opt64());
}
TEST(Optional, NoneComparisons) {
using opt = Optional<int>;
EXPECT_TRUE(opt() == none);
EXPECT_TRUE(none == opt());
EXPECT_FALSE(opt(1) == none);
EXPECT_FALSE(none == opt(1));
EXPECT_FALSE(opt() != none);
EXPECT_FALSE(none != opt());
EXPECT_TRUE(opt(1) != none);
EXPECT_TRUE(none != opt(1));
EXPECT_FALSE(opt() < none);
EXPECT_FALSE(none < opt());
EXPECT_FALSE(opt(1) < none);
EXPECT_TRUE(none < opt(1));
EXPECT_FALSE(opt() > none);
EXPECT_FALSE(none > opt());
EXPECT_FALSE(none > opt(1));
EXPECT_TRUE(opt(1) > none);
EXPECT_TRUE(opt() <= none);
EXPECT_TRUE(none <= opt());
EXPECT_FALSE(opt(1) <= none);
EXPECT_TRUE(none <= opt(1));
EXPECT_TRUE(opt() >= none);
EXPECT_TRUE(none >= opt());
EXPECT_TRUE(opt(1) >= none);
EXPECT_FALSE(none >= opt(1));
}
TEST(Optional, Conversions) {
Optional<bool> mbool;
Optional<short> mshort;
Optional<char*> mstr;
Optional<int> mint;
// These don't compile
// bool b = mbool;
// short s = mshort;
// char* c = mstr;
// int x = mint;
// char* c(mstr);
// short s(mshort);
// int x(mint);
// intended explicit operator bool, for if (opt).
bool b(mbool);
EXPECT_FALSE(b);
// Truthy tests work and are not ambiguous
if (mbool && mshort && mstr && mint) { // only checks not-empty
if (*mbool && *mshort && *mstr && *mint) { // only checks value
}
}
mbool = false;
EXPECT_TRUE(bool(mbool));
EXPECT_FALSE(*mbool);
mbool = true;
EXPECT_TRUE(bool(mbool));
EXPECT_TRUE(*mbool);
mbool = none;
EXPECT_FALSE(bool(mbool));
// No conversion allowed; does not compile
// EXPECT_TRUE(mbool == false);
}
TEST(Optional, Pointee) {
Optional<int> x;
EXPECT_FALSE(get_pointer(x));
x = 1;
EXPECT_TRUE(get_pointer(x));
*get_pointer(x) = 2;
EXPECT_TRUE(*x == 2);
x = none;
EXPECT_FALSE(get_pointer(x));
}
namespace {
class ConstructibleWithArgsOnly {
public:
explicit ConstructibleWithArgsOnly(int, double) {}
ConstructibleWithArgsOnly() = delete;
ConstructibleWithArgsOnly(const ConstructibleWithArgsOnly&) = delete;
ConstructibleWithArgsOnly(ConstructibleWithArgsOnly&&) = delete;
ConstructibleWithArgsOnly& operator=(const ConstructibleWithArgsOnly&) =
delete;
ConstructibleWithArgsOnly& operator=(ConstructibleWithArgsOnly&&) = delete;
};
class ConstructibleWithInitializerListAndArgsOnly {
public:
ConstructibleWithInitializerListAndArgsOnly(
std::initializer_list<int>, double) {}
ConstructibleWithInitializerListAndArgsOnly() = delete;
ConstructibleWithInitializerListAndArgsOnly(
const ConstructibleWithInitializerListAndArgsOnly&) = delete;
ConstructibleWithInitializerListAndArgsOnly(
ConstructibleWithInitializerListAndArgsOnly&&) = delete;
ConstructibleWithInitializerListAndArgsOnly& operator=(
const ConstructibleWithInitializerListAndArgsOnly&) = delete;
ConstructibleWithInitializerListAndArgsOnly& operator=(
ConstructibleWithInitializerListAndArgsOnly&&) = delete;
};
} // namespace
TEST(Optional, MakeOptional) {
// const L-value version
const std::string s("abc");
auto optStr = folly::make_optional(s);
ASSERT_TRUE(optStr.has_value());
EXPECT_EQ(*optStr, "abc");
*optStr = "cde";
EXPECT_EQ(s, "abc");
EXPECT_EQ(*optStr, "cde");
// L-value version
std::string s2("abc");
auto optStr2 = folly::make_optional(s2);
ASSERT_TRUE(optStr2.has_value());
EXPECT_EQ(*optStr2, "abc");
*optStr2 = "cde";
// it's vital to check that s2 wasn't clobbered
EXPECT_EQ(s2, "abc");
// L-value reference version
std::string& s3(s2);
auto optStr3 = folly::make_optional(s3);
ASSERT_TRUE(optStr3.has_value());
EXPECT_EQ(*optStr3, "abc");
*optStr3 = "cde";
EXPECT_EQ(s3, "abc");
// R-value ref version
unique_ptr<int> pInt(new int(3));
auto optIntPtr = folly::make_optional(std::move(pInt));
EXPECT_TRUE(pInt.get() == nullptr);
ASSERT_TRUE(optIntPtr.has_value());
EXPECT_EQ(**optIntPtr, 3);
// variadic version
{
auto&& optional = make_optional<ConstructibleWithArgsOnly>(int{}, double{});
std::ignore = optional;
}
{
using Type = ConstructibleWithInitializerListAndArgsOnly;
auto&& optional = make_optional<Type>({int{}}, double{});
std::ignore = optional;
}
}
TEST(Optional, InitializerListConstruct) {
using Type = ConstructibleWithInitializerListAndArgsOnly;
auto&& optional = Optional<Type>{std::in_place, {int{}}, double{}};
std::ignore = optional;
}
TEST(Optional, TestDisambiguationMakeOptionalVariants) {
{
auto optional = make_optional<int>(1);
std::ignore = optional;
}
{
auto optional = make_optional(1);
std::ignore = optional;
}
}
TEST(Optional, SelfAssignment) {
Optional<int> a = 42;
a = static_cast<decltype(a)&>(a); // suppress self-assign warning
ASSERT_TRUE(a.has_value() && a.value() == 42);
Optional<int> b = 23333333;
b = static_cast<decltype(b)&&>(b); // suppress self-move warning
ASSERT_TRUE(b.has_value() && b.value() == 23333333);
}
namespace {
class ContainsOptional {
public:
ContainsOptional() {}
explicit ContainsOptional(int x) : opt_(x) {}
bool hasValue() const { return opt_.has_value(); }
int value() const { return opt_.value(); }
ContainsOptional(const ContainsOptional& other) = default;
ContainsOptional& operator=(const ContainsOptional& other) = default;
ContainsOptional(ContainsOptional&& other) = default;
ContainsOptional& operator=(ContainsOptional&& other) = default;
private:
Optional<int> opt_;
};
} // namespace
/**
* Test that a class containing an Optional can be copy and move assigned.
*/
TEST(Optional, AssignmentContained) {
{
ContainsOptional source(5), target;
target = source;
EXPECT_TRUE(target.hasValue());
EXPECT_EQ(5, target.value());
}
{
ContainsOptional source(5), target;
target = std::move(source);
EXPECT_TRUE(target.hasValue());
EXPECT_EQ(5, target.value());
EXPECT_FALSE(source.hasValue());
}
{
ContainsOptional opt_uninit, target(10);
target = opt_uninit;
EXPECT_FALSE(target.hasValue());
}
}
TEST(Optional, Exceptions) {
Optional<int> empty;
EXPECT_THROW(empty.value(), OptionalEmptyException);
}
TEST(Optional, NoThrowDefaultConstructible) {
EXPECT_TRUE(std::is_nothrow_default_constructible<Optional<bool>>::value);
}
namespace {
struct NoDestructor {};
struct WithDestructor {
~WithDestructor();
};
} // namespace
TEST(Optional, TriviallyDestructible) {
// These could all be static_asserts but EXPECT_* give much nicer output on
// failure.
EXPECT_TRUE(std::is_trivially_destructible<Optional<NoDestructor>>::value);
EXPECT_TRUE(std::is_trivially_destructible<Optional<int>>::value);
EXPECT_FALSE(std::is_trivially_destructible<Optional<WithDestructor>>::value);
}
TEST(Optional, Hash) {
// Test it's usable in std::unordered map (compile time check)
std::unordered_map<Optional<int>, Optional<int>> obj;
// Also check the std::hash template can be instantiated by the compiler
std::hash<Optional<int>>()(none);
std::hash<Optional<int>>()(3);
}
namespace {
struct WithConstMember {
/* implicit */ WithConstMember(int val) : x(val) {}
const int x;
};
// Make this opaque to the optimizer by preventing inlining.
FOLLY_NOINLINE void replaceWith2(Optional<WithConstMember>& o) {
o.emplace(2);
}
} // namespace
TEST(Optional, ConstMember) {
// Verify that the compiler doesn't optimize out the second load of
// o->x based on the assumption that the field is const.
//
// Current Optional implementation doesn't defend against that
// assumption, thus replacing an optional where the object has const
// members is technically UB and would require wrapping each access
// to the storage with std::launder, but this prevents useful
// optimizations.
//
// Implementations of std::optional in both libstdc++ and libc++ are
// subject to the same UB. It is then reasonable to believe that
// major compilers don't rely on the constness assumption.
Optional<WithConstMember> o(1);
int sum = 0;
sum += o->x;
replaceWith2(o);
sum += o->x;
EXPECT_EQ(sum, 3);
}
TEST(Optional, NoneMatchesNullopt) {
auto op = make_optional<int>(10);
op = {};
EXPECT_FALSE(op.has_value());
op = make_optional<int>(20);
op = none;
EXPECT_FALSE(op.has_value());
}
TEST(Optional, StdOptionalConversions) {
folly::Optional<int> f = 42;
std::optional<int> s = static_cast<std::optional<int>>(f);
EXPECT_EQ(*s, 42);
EXPECT_EQ(s, f.toStdOptional());
EXPECT_TRUE(f);
f = static_cast<folly::Optional<int>>(s);
EXPECT_EQ(*f, 42);
EXPECT_TRUE(s);
folly::Optional<int> e;
EXPECT_FALSE(static_cast<std::optional<int>>(e));
EXPECT_FALSE(e.toStdOptional());
const folly::Optional<int> fc = 12;
s = static_cast<std::optional<int>>(fc);
EXPECT_EQ(*s, 12);
folly::Optional<std::unique_ptr<int>> fp = std::make_unique<int>(42);
std::optional<std::unique_ptr<int>> sp(std::move(fp));
EXPECT_EQ(**sp, 42);
EXPECT_FALSE(fp);
fp = static_cast<folly::Optional<std::unique_ptr<int>>>(std::move(sp));
EXPECT_EQ(**fp, 42);
EXPECT_FALSE(sp);
folly::Optional<std::unique_ptr<int>> fp2 = std::make_unique<int>(42);
auto sp2 = std::move(fp2).toStdOptional();
EXPECT_EQ(**sp2, 42);
EXPECT_FALSE(fp2);
}
TEST(Optional, MovedFromOptionalIsEmpty) {
// moved-from folly::Optional is empty, unlike std::optional!
folly::Optional<int> x = 1;
EXPECT_TRUE(x);
auto y = std::move(x);
// NOLINTNEXTLINE(bugprone-use-after-move)
EXPECT_FALSE(x);
EXPECT_TRUE(y);
folly::Optional<int> z;
z = std::move(y);
// NOLINTNEXTLINE(bugprone-use-after-move)
EXPECT_FALSE(y);
EXPECT_TRUE(z);
folly::Optional<std::string> str("hello");
EXPECT_TRUE(str);
auto str2 = std::move(str);
// NOLINTNEXTLINE(bugprone-use-after-move)
EXPECT_FALSE(str);
EXPECT_TRUE(str2);
folly::Optional<std::string> str3;
str3 = std::move(str2);
// NOLINTNEXTLINE(bugprone-use-after-move)
EXPECT_FALSE(str2);
EXPECT_TRUE(str3);
}
} // namespace folly
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