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// { dg-options "-std=gnu++23" }
// { dg-do compile { target c++23 } }
#include <expected>
#include <type_traits>
// Default construction
template<typename T, typename E>
constexpr bool default_constructible
= std::is_default_constructible_v<std::expected<T, E>>;
struct A { A(int); };
static_assert( default_constructible< int, int > );
static_assert( default_constructible< A, int > == false );
static_assert( default_constructible< int, A > );
static_assert( default_constructible< A, A > == false );
static_assert( default_constructible< int, A > );
static_assert( default_constructible< void, int > );
// Destruction
template<typename T, typename E>
constexpr bool trivially_destructible
= std::is_trivially_destructible_v<std::expected<T, E>>;
struct B { ~B(); };
static_assert( trivially_destructible< int, int > );
static_assert( trivially_destructible< B, int > == false );
static_assert( trivially_destructible< int, B > == false );
static_assert( trivially_destructible< B, B > == false );
static_assert( trivially_destructible< void, int > );
static_assert( trivially_destructible< void, B > == false );
enum Result { No, Yes, NoThrow, Trivial };
// Copy construction
template<typename T, typename E>
constexpr Result copy_constructible
= std::is_trivially_copy_constructible_v<std::expected<T, E>> ? Trivial
: std::is_copy_constructible_v<std::expected<T, E>> ? Yes
: No;
struct C { C(const C&); };
struct D { D(D&&); };
static_assert( copy_constructible< int, int > == Trivial );
static_assert( copy_constructible< C, C > == Yes );
static_assert( copy_constructible< C, int > == Yes );
static_assert( copy_constructible< int, C > == Yes );
static_assert( copy_constructible< int, D > == No );
static_assert( copy_constructible< D, int > == No );
static_assert( copy_constructible< D, D > == No );
static_assert( copy_constructible< void, int > == Trivial );
static_assert( copy_constructible< void, C > == Yes );
static_assert( copy_constructible< void, D > == No );
// Move construction
template<typename T, typename E>
constexpr Result move_constructible
= std::is_trivially_move_constructible_v<std::expected<T, E>> ? Trivial
: std::is_nothrow_move_constructible_v<std::expected<T, E>> ? NoThrow
: std::is_move_constructible_v<std::expected<T, E>> ? Yes
: No;
struct E { E(E&&) noexcept; };
static_assert( move_constructible< int, int > == Trivial );
static_assert( move_constructible< C, C > == Yes );
static_assert( move_constructible< C, int > == Yes );
static_assert( move_constructible< int, C > == Yes );
static_assert( move_constructible< D, D > == Yes );
static_assert( move_constructible< D, int > == Yes );
static_assert( move_constructible< int, D > == Yes );
static_assert( move_constructible< E, E > == NoThrow );
static_assert( move_constructible< E, int > == NoThrow );
static_assert( move_constructible< int, E > == NoThrow );
static_assert( move_constructible< void, int > == Trivial );
static_assert( move_constructible< void, C > == Yes );
static_assert( move_constructible< void, D > == Yes );
static_assert( move_constructible< void, E > == NoThrow );
// Copy assignment
template<typename T, typename E>
constexpr bool copy_assignable
= std::is_copy_assignable_v<std::expected<T, E>>;
struct F { F(F&&); F& operator=(const F&); }; // not copy-constructible
struct G { G(const G&); G(G&&); G& operator=(const G&); }; // throwing move
static_assert( copy_assignable< int, int > );
static_assert( copy_assignable< F, int > == false );
static_assert( copy_assignable< int, F > == false );
static_assert( copy_assignable< F, F > == false );
static_assert( copy_assignable< G, int > );
static_assert( copy_assignable< int, G > );
static_assert( copy_assignable< G, G > == false );
static_assert( copy_assignable< void, int > );
static_assert( copy_assignable< void, F > == false );
static_assert( copy_assignable< void, G > );
// Move assignment
template<typename T, typename E>
constexpr bool move_assignable
= std::is_move_assignable_v<std::expected<T, E>>;
static_assert( move_assignable< int, int > );
static_assert( move_assignable< F, int > );
static_assert( move_assignable< int, F > );
static_assert( move_assignable< F, F > == false );
static_assert( move_assignable< G, int > );
static_assert( move_assignable< int, G > );
static_assert( move_assignable< G, G > == false );
static_assert( move_assignable< void, int > );
static_assert( move_assignable< void, F > );
static_assert( move_assignable< void, G > );
// QoI properties
static_assert( sizeof(std::expected<char, unsigned char>) == 2 );
static_assert( sizeof(std::expected<void, char>) == 2 );
static_assert( sizeof(std::expected<void*, char>) == 2 * __alignof(void*) );
static_assert( alignof(std::expected<void, char>) == 1 );
static_assert( alignof(std::expected<void*, char>) == alignof(void*) );
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