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<expected>: Add deleted copy function overloads #4837

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Merged
merged 2 commits into from
Aug 8, 2024
Merged

<expected>: Add deleted copy function overloads #4837

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90fca27
Add deleted overloads to `expected`
frederick-vs-ja Jul 13, 2024
e5afb0b
Work around VSO-2188364 "EDG assertion failed in conversion_for_direc…
StephanTLavavej Aug 6, 2024
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8 changes: 8 additions & 0 deletions stl/inc/expected
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Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,8 @@ public:
is_trivially_copy_constructible_v<_Ty> && is_trivially_copy_constructible_v<_Err> = default;
// clang-format on

expected(const expected&) = delete;

constexpr expected(expected&& _Other) noexcept(
is_nothrow_move_constructible_v<_Ty> && is_nothrow_move_constructible_v<_Err>)
requires (!(is_trivially_move_constructible_v<_Ty> && is_trivially_move_constructible_v<_Err>)
Expand Down Expand Up @@ -441,6 +443,8 @@ public:
&& _Trivially_copy_constructible_assignable_destructible<_Err>
= default;

expected& operator=(const expected&) = delete;

constexpr expected& operator=(expected&& _Other) noexcept(
is_nothrow_move_constructible_v<_Ty> && is_nothrow_move_constructible_v<_Err>
&& is_nothrow_move_assignable_v<_Ty> && is_nothrow_move_assignable_v<_Err>)
Expand Down Expand Up @@ -1243,6 +1247,8 @@ public:
expected(const expected&) requires is_trivially_copy_constructible_v<_Err> = default;
// clang-format on

expected(const expected&) = delete;

constexpr expected(expected&& _Other) noexcept(is_nothrow_move_constructible_v<_Err>)
requires (!is_trivially_move_constructible_v<_Err> && is_move_constructible_v<_Err>)
: _Has_value(_Other._Has_value) {
Expand Down Expand Up @@ -1344,6 +1350,8 @@ public:
requires _Expected_unary_copy_assignable<_Err> && _Trivially_copy_constructible_assignable_destructible<_Err>
= default;

expected& operator=(const expected&) = delete;

constexpr expected& operator=(expected&& _Other) noexcept(
is_nothrow_move_constructible_v<_Err> && is_nothrow_move_assignable_v<_Err>)
requires _Expected_unary_move_assignable<_Err>
Expand Down
47 changes: 47 additions & 0 deletions tests/std/tests/P0323R12_expected/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2343,6 +2343,53 @@ constexpr bool test_inherited_constructors() {

static_assert(test_inherited_constructors());

// Test GH-4279 "Add deleted function overloads to expected"

template <class T, class E>
struct ambiguating_expected_copy_constructor_caller {
struct const_lvalue_taker {
const_lvalue_taker(const expected<T, E>&) {}
};

void operator()(expected<T, E>) {}
void operator()(const_lvalue_taker) {}
};

template <class T, class E>
struct ambiguating_expected_assignment_source {
operator const expected<T, E>&() && {
return ex;
}

operator expected<T, E>&&() && {
return move(ex);
}

expected<T, E> ex;
};

struct move_only {
move_only() = default;
move_only(move_only&&) = default;
move_only& operator=(move_only&&) = default;
};

static_assert(is_invocable_v<ambiguating_expected_copy_constructor_caller<int, char>, const expected<int, char>&>);
static_assert(is_invocable_v<ambiguating_expected_copy_constructor_caller<void, int>, const expected<void, int>&>);
static_assert(
!is_invocable_v<ambiguating_expected_copy_constructor_caller<move_only, char>, const expected<move_only, char>&>);
static_assert(
!is_invocable_v<ambiguating_expected_copy_constructor_caller<void, move_only>, const expected<void, move_only>&>);

#ifndef __EDG__ // TRANSITION, VSO-1601179
static_assert(!is_assignable_v<expected<int, char>&, ambiguating_expected_assignment_source<int, char>>);
static_assert(!is_assignable_v<expected<void, int>&, ambiguating_expected_assignment_source<void, int>>);
#endif // ^^^ no workaround ^^^
#ifndef __EDG__ // TRANSITION, VSO-2188364
static_assert(!is_assignable_v<expected<move_only, char>&, ambiguating_expected_assignment_source<move_only, char>>);
static_assert(!is_assignable_v<expected<void, move_only>&, ambiguating_expected_assignment_source<void, move_only>>);
#endif // ^^^ no workaround ^^^

int main() {
test_unexpected::test_all();
static_assert(test_unexpected::test_all());
Expand Down