A type carrying one of (i) a successful T (ii) a disappointment EC (iii) a failure EP (iv) both a disappointment EC and a failure EP, with NoValuePolicy specifying what to do if one tries to read state which isn’t there.

1. basic_outcome() = delete

   The default constructor (disabled).

2. basic_outcome(basic_outcome &&)

   Move constructor. Constexpr, triviality and noexcept propagating.

3. basic_outcome(const basic_outcome &)

   Copy constructor. Constexpr, triviality and noexcept propagating.

4. basic_outcome &operator=(basic_outcome &&)

   Move assignment. Constexpr, triviality and noexcept propagating.

5. basic_outcome &operator=(const basic_outcome &)

   Copy assignment. Constexpr, triviality and noexcept propagating.

6. ~basic_outcome()

   Destructor. Constexpr, triviality and noexcept propagating.

7. basic_outcome(Args...) = delete

   Disabling catchall constructor used to give useful diagnostic error when trying to use non-inplace constructors when predicate::constructors_enabled is false.

8. basic_outcome(X &&) = delete

   Disabling implicit constructor used to give useful diagnostic error when trying to use implicit constructors when predicate::implicit_constructors_enabled is false.

9. basic_outcome(R &&)

   Implicit value_type constructor. Available if predicate::enable_value_converting_constructor<R> is true. Constexpr, triviality and noexcept propagating.

10. basic_outcome(S &&)

    Implicit error_type constructor. Available if predicate::enable_error_converting_constructor<S> is true. Constexpr, triviality and noexcept propagating.

11. basic_outcome(ErrorCondEnum &&)

    Implicit error_type from ErrorCondEnum constructor. Available if predicate::enable_error_condition_converting_constructor<ErrorCondEnum> is true. Constexpr, triviality and noexcept propagating.

12. basic_outcome(P &&)

    Implicit exception_type constructor. Available if predicate::enable_exception_converting_constructor<P> is true. Constexpr, triviality and noexcept propagating.

13. basic_outcome(S &&, P &&)

    Implicit error_type + exception_type constructor. Available if predicate::enable_error_exception_converting_constructor<S, P> is true. Constexpr, triviality and noexcept propagating.

14. explicit basic_outcome(concepts::value_or_error<T, E> &&)

    Explicit converting constructor from concepts::value_or_error<T, E> concept matching types. Available if convert::value_or_error<> permits it. Constexpr, triviality and noexcept propagating.

15. explicit basic_outcome(const basic_outcome<A, B, C, D> &)

    Explicit converting copy constructor from compatible basic_outcome. Available if predicate::enable_compatible_conversion<A, B, C, D> is true. Constexpr, triviality and noexcept propagating.

16. explicit basic_outcome(basic_outcome<A, B, C, D> &&)

    Explicit converting move constructor from compatible basic_outcome. Available if predicate::enable_compatible_conversion<A, B, C, D> is true. Constexpr, triviality and noexcept propagating.

17. explicit basic_outcome(const basic_result<A, B, C> &)

    Explicit converting copy constructor from compatible basic_result. Available if predicate::enable_compatible_conversion<A, B, void, C> is true. Constexpr, triviality and noexcept propagating.

18. explicit basic_outcome(basic_result<A, B, C> &&)

    Explicit converting move constructor from compatible basic_result. Available if predicate::enable_compatible_conversion<A, B, void, C> is true. Constexpr, triviality and noexcept propagating.

19. explicit basic_outcome(const basic_result<A, B, C> &)

    Explicit converting copy constructor from compatible basic_result. Available if predicate::enable_make_error_code_compatible_conversion<A, B, void, C> is true. Constexpr, triviality and noexcept propagating.

20. explicit basic_outcome(basic_result<A, B, C> &&)

    Explicit converting move constructor from compatible basic_result. Available if predicate::enable_make_error_code_compatible_conversion<A, B, void, C> is true. Constexpr, triviality and noexcept propagating.

21. explicit basic_outcome(in_place_type_t<value_type_if_enabled>, Args ...)

    Explicit inplace value constructor. Available if predicate::enable_inplace_value_constructor<Args ...> is true. Constexpr, triviality and noexcept propagating.

22. explicit basic_outcome(in_place_type_t<value_type_if_enabled>, std::initializer_list<U>, Args ...)

    Explicit inplace value constructor. Available if predicate::enable_inplace_value_constructor<std::initializer_list<U>, Args ...> is true. Constexpr, triviality and noexcept propagating.

23. explicit basic_outcome(in_place_type_t<error_type_if_enabled>, Args ...)

    Explicit inplace error constructor. Available if predicate::enable_inplace_error_constructor<Args ...> is true. Constexpr, triviality and noexcept propagating.

24. explicit basic_outcome(in_place_type_t<error_type_if_enabled>, std::initializer_list<U>, Args ...)

    Explicit inplace error constructor. Available if predicate::enable_inplace_error_constructor<std::initializer_list<U>, Args ...> is true. Constexpr, triviality and noexcept propagating.

25. explicit basic_outcome(in_place_type_t<exception_type_if_enabled>, Args ...)

    Explicit inplace exception constructor. Available if predicate::enable_inplace_exception_constructor<Args ...> is true. Constexpr, triviality and noexcept propagating.

26. explicit basic_outcome(in_place_type_t<exception_type_if_enabled>, std::initializer_list<U>, Args ...)

    Explicit inplace exception constructor. Available if predicate::enable_inplace_exception_constructor<std::initializer_list<U>, Args ...> is true. Constexpr, triviality and noexcept propagating.

27. basic_outcome(A1 &&, A2 &&, Args ...)

    Implicit inplace value or error or exception constructor. Available if predicate::enable_inplace_value_error_exception_constructor<A1, A2, Args ...> is true. Constexpr, triviality and noexcept propagating.

28. basic_outcome(const success_type<T> &)

    Implicit value-from-success-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<T, void, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

29. basic_outcome(success_type<T> &&)

    Implicit value-from-success-type-sugar move constructor. Available if predicate::enable_compatible_conversion<T, void, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

30. basic_outcome(const failure_type<EC> &)

    Implicit error-from-failure-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<void, EC, void, void> is true. Constexpr, triviality and noexcept propagating.

31. basic_outcome(failure_type<EC> &&)

    Implicit error-from-failure-type-sugar move constructor. Available if predicate::enable_compatible_conversion<void, EC, void, void> is true. Constexpr, triviality and noexcept propagating.

32. basic_outcome(const failure_type<EC> &)

    Implicit error-from-failure-type-sugar copy constructor. Available if predicate::enable_make_error_code_compatible_conversion<void, EC, void, void> is true. Constexpr, triviality and noexcept propagating.

33. basic_outcome(failure_type<EC> &&)

    Implicit error-from-failure-type-sugar move constructor. Available if predicate::enable_make_error_code_compatible_conversion<void, EC, void, void> is true. Constexpr, triviality and noexcept propagating.

34. basic_outcome(const failure_type<EP> &)

    Implicit exception-from-failure-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<void, void, EP, void> is true. Constexpr, triviality and noexcept propagating.

35. basic_outcome(failure_type<EP> &&)

    Implicit exception-from-failure-type-sugar move constructor. Available if predicate::enable_compatible_conversion<void, void, EP, void> is true. Constexpr, triviality and noexcept propagating.

36. basic_outcome(const failure_type<EC, EP> &)

    Implicit error-and-exception-from-failure-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<void, EC, EP, void> is true. Constexpr, triviality and noexcept propagating.

37. basic_outcome(failure_type<EC, EP> &&)

    Implicit error-and-exception-from-failure-type-sugar move constructor. Available if predicate::enable_compatible_conversion<void, EC, EP, void> is true. Constexpr, triviality and noexcept propagating.

38. explicit operator bool() const noexcept

    Returns true if a value is present. Constexpr, never throws.

39. bool has_value() const noexcept

    Returns true if a value is present. Constexpr, never throws.

40. bool has_error() const noexcept

    Returns true if an error is present. Constexpr, never throws.

41. bool has_exception() const noexcept

    Returns true if an exception is present. Constexpr, never throws.

42. bool has_failure() const noexcept

    Returns true if there is either an error or an exception. Constexpr, never throws.

43. value_type &assume_value() & noexcept

    Narrow contract lvalue reference observer of any value present. Constexpr propagating, never throws.

44. const value_type &assume_value() const & noexcept

    Narrow contract const lvalue reference observer of any value present. Constexpr propagating, never throws.

45. value_type &&assume_value() && noexcept

    Narrow contract rvalue reference observer of any value present. Constexpr propagating, never throws.

46. const value_type &&assume_value() const && noexcept

    Narrow contract const rvalue reference observer of any value present. Constexpr propagating, never throws.

47. value_type &value() &

    Wide contract lvalue reference observer of any value present. Constexpr propagating.

48. const value_type &value() const &

    Wide contract const lvalue reference observer of any value present. Constexpr propagating.

49. value_type &&value() &&

    Wide contract rvalue reference observer of any value present. Constexpr propagating.

50. const value_type &&value() const &&

    Wide contract const rvalue reference observer of any value present. Constexpr propagating.

51. error_type &assume_error() & noexcept

    Narrow contract lvalue reference observer of the stored error. Constexpr propagating, never throws.

52. const error_type &assume_error() const & noexcept

    Narrow contract const lvalue reference observer of the stored error. Constexpr propagating, never throws.

53. error_type &&assume_error() && noexcept

    Narrow contract rvalue reference observer of the stored error. Constexpr propagating, never throws.

54. const error_type &&assume_error() const && noexcept

    Narrow contract const rvalue reference observer of the stored error. Constexpr propagating, never throws.

55. error_type &error() &

    Wide contract lvalue reference observer of the stored error. Constexpr propagating.

56. const error_type &error() const &

    Wide contract const lvalue reference observer of the stored error. Constexpr propagating.

57. error_type &&error() &&

    Wide contract rvalue reference observer of the stored error. Constexpr propagating.

58. const error_type &&error() const &&

    Wide contract const rvalue reference observer of the stored error. Constexpr propagating.

59. exception_type &assume_exception() & noexcept

    Narrow contract lvalue reference observer of the stored exception. Constexpr propagating, never throws.

60. const exception_type &assume_exception() const & noexcept

    Narrow contract const lvalue reference observer of the stored exception. Constexpr propagating, never throws.

61. const exception_type &&assume_exception() const && noexcept

    Narrow contract const rvalue reference observer of the stored exception. Constexpr propagating, never throws.

62. exception_type &&assume_exception() && noexcept

    Narrow contract rvalue reference observer of the stored exception. Constexpr propagating, never throws.

63. exception_type &exception() &

    Wide contract lvalue reference observer of the stored exception. Constexpr propagating.

64. const exception_type &exception() const &

    Wide contract const lvalue reference observer of the stored exception. Constexpr propagating.

65. exception_type &&exception() &&

    Wide contract rvalue reference observer of the stored exception. Constexpr propagating.

66. const exception_type &&exception() const &&

    Wide contract const rvalue reference observer of the stored exception. Constexpr propagating.

67. exception_type failure() const noexcept

    Synthesising observer of the stored exception or error. Available if the traits is_error_code_available<T> and is_exception_ptr_available<T> are both true. Never throws.

68. bool operator==(const basic_result<A, B, C> &) const

    Returns true if this outcome compares equal to the other result. Constexpr and noexcept propagating.

69. bool operator==(const basic_outcome<A, B, C, D> &) const

    Returns true if this outcome compares equal to the other outcome. Constexpr and noexcept propagating.

70. bool operator==(const success_type<A> &) const

    Returns true if this result compares equal to the success type sugar. Constexpr and noexcept propagating.

71. bool operator==(const failure_type<A, B> &) const

    Returns true if this outcome compares equal to the failure type sugar. Constexpr and noexcept propagating.

72. bool operator!=(const basic_result<A, B, C> &) const

    Returns true if this outcome does not compare equal to the other result. Constexpr and noexcept propagating.

73. bool operator!=(const basic_outcome<A, B, C, D> &) const

    Returns true if this outcome does not compare equal to the other outcome. Constexpr and noexcept propagating.

74. bool operator!=(const success_type<A> &) const

    Returns true if this outcome does not compare equal to the success type sugar. Constexpr and noexcept propagating.

75. bool operator!=(const failure_type<A, B> &) const

    Returns true if this outcome does not compare equal to the failure type sugar. Constexpr and noexcept propagating.

76. void swap(basic_outcome &)

    Swap one basic_outcome with another, with the strong guarantee. Noexcept propagating.

77. failure_type<error_type, exception_type> as_failure() const &

    Return the output from free function failure() containing a copy of any errored and/or excepted state.

78. failure_type<error_type, exception_type> as_failure() &&

    Return the output from free function failure() containing a move of any errored and/or excepted state.

A sum type carrying either a successful T, or a disappointment E, with NoValuePolicy specifying what to do if one tries to read state which isn’t there.

1. basic_result() = delete

   The default constructor (disabled).

2. basic_result(basic_result &&)

   Move constructor. Constexpr, triviality and noexcept propagating.

3. basic_result(const basic_result &)

   Copy constructor. Constexpr, triviality and noexcept propagating.

4. basic_result &operator=(basic_result &&)

   Move assignment. Constexpr, triviality and noexcept propagating.

5. basic_result &operator=(const basic_result &)

   Copy assignment. Constexpr, triviality and noexcept propagating.

6. ~basic_result()

   Destructor. Constexpr, triviality and noexcept propagating.

7. basic_result(Args...) = delete

   Disabling catchall constructor used to give useful diagnostic error when trying to use non-inplace constructors when predicate::constructors_enabled is false.

8. basic_result(X &&) = delete

   Disabling implicit constructor used to give useful diagnostic error when trying to use implicit constructors when predicate::implicit_constructors_enabled is false.

9. basic_result(R &&)

   Implicit value_type constructor. Available if predicate::enable_value_converting_constructor<R> is true. Constexpr, triviality and noexcept propagating.

10. basic_result(S &&)

    Implicit error_type constructor. Available if predicate::enable_error_converting_constructor<S> is true. Constexpr, triviality and noexcept propagating.

11. basic_result(ErrorCondEnum &&)

    Implicit error_type from ErrorCondEnum constructor. Available if predicate::enable_error_condition_converting_constructor<ErrorCondEnum> is true. Constexpr, triviality and noexcept propagating.

12. explicit basic_result(concepts::value_or_error<T, E> &&)

    Explicit converting constructor from concepts::value_or_error<T, E> concept matching types. Available if convert::value_or_error<> permits it. Constexpr, triviality and noexcept propagating.

13. explicit basic_result(const basic_result<R, S, P> &)

    Explicit converting copy constructor from compatible basic_result. Available if predicate::enable_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

14. explicit basic_result(basic_result<R, S, P> &&)

    Explicit converting move constructor from compatible basic_result. Available if predicate::enable_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

15. explicit basic_result(const basic_result<R, S, P> &)

    Explicit converting copy constructor from compatible basic_result. Available if predicate::enable_make_error_code_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

16. explicit basic_result(basic_result<R, S, P> &&)

    Explicit converting move constructor from compatible basic_result. Available if predicate::enable_make_error_code_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

17. explicit basic_result(const basic_result<R, S, P> &)

    Explicit converting copy constructor from compatible basic_result. Available if predicate::enable_make_exception_ptr_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

18. explicit basic_result(basic_result<R, S, P> &&)

    Explicit converting move constructor from compatible basic_result. Available if predicate::enable_make_exception_ptr_compatible_conversion<R, S, P> is true. Constexpr, triviality and noexcept propagating.

19. explicit basic_result(in_place_type_t<value_type_if_enabled>, Args ...)

    Explicit inplace value constructor. Available if predicate::enable_inplace_value_constructor<Args ...> is true. Constexpr, triviality and noexcept propagating.

20. explicit basic_result(in_place_type_t<value_type_if_enabled>, std::initializer_list<U>, Args ...)

    Explicit inplace value constructor. Available if predicate::enable_inplace_value_constructor<std::initializer_list<U>, Args ...> is true. Constexpr, triviality and noexcept propagating.

21. explicit basic_result(in_place_type_t<error_type_if_enabled>, Args ...)

    Explicit inplace error constructor. Available if predicate::enable_inplace_error_constructor<Args ...> is true. Constexpr, triviality and noexcept propagating.

22. explicit basic_result(in_place_type_t<error_type_if_enabled>, std::initializer_list<U>, Args ...)

    Explicit inplace error constructor. Available if predicate::enable_inplace_error_constructor<std::initializer_list<U>, Args ...> is true. Constexpr, triviality and noexcept propagating.

23. basic_result(A1 &&, A2 &&, Args ...)

    Implicit inplace value or error constructor. Available if predicate::enable_inplace_value_error_constructor<A1, A2, Args ...> is true. Constexpr, triviality and noexcept propagating.

24. basic_result(const success_type<T> &)

    Implicit value-from-success-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<T, void, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

25. basic_result(success_type<T> &&)

    Implicit value-from-success-type-sugar move constructor. Available if predicate::enable_compatible_conversion<T, void, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

26. basic_result(const failure_type<T> &)

    Implicit error-from-failure-type-sugar copy constructor. Available if predicate::enable_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

27. basic_result(failure_type<T> &&)

    Implicit error-from-failure-type-sugar move constructor. Available if predicate::enable_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

28. basic_result(const failure_type<T> &)

    Implicit error-from-failure-type-sugar copy constructor. Available if predicate::enable_make_error_code_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

29. basic_result(failure_type<T> &&)

    Implicit error-from-failure-type-sugar move constructor. Available if predicate::enable_make_error_code_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

30. basic_result(const failure_type<T> &)

    Implicit error-from-failure-type-sugar copy constructor. Available if predicate::enable_make_exception_ptr_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

31. basic_result(failure_type<T> &&)

    Implicit error-from-failure-type-sugar move constructor. Available if predicate::enable_make_exception_ptr_compatible_conversion<void, T, void> is true, or T is void. Constexpr, triviality and noexcept propagating.

32. explicit operator bool() const noexcept

    Returns true if a value is present. Constexpr, never throws.

33. bool has_value() const noexcept

    Returns true if a value is present. Constexpr, never throws.

34. bool has_error() const noexcept

    Returns true if an error is present. Constexpr, never throws.

35. bool has_exception() const noexcept

    Always returns false for basic_result. Constexpr, never throws.

36. bool has_failure() const noexcept

    Returns true if there is either an error or an exception. Constexpr, never throws.

37. bool has_lost_consistency() const noexcept

    Returns true if a preceding swap involving this object failed to preserve the strong guarantee. Constexpr, never throws.

38. value_type &assume_value() & noexcept

    Narrow contract lvalue reference observer of any value present. Constexpr propagating, never throws.

39. const value_type &assume_value() const & noexcept

    Narrow contract const lvalue reference observer of any value present. Constexpr propagating, never throws.

40. value_type &&assume_value() && noexcept

    Narrow contract rvalue reference observer of any value present. Constexpr propagating, never throws.

41. const value_type &&assume_value() const && noexcept

    Narrow contract const rvalue reference observer of any value present. Constexpr propagating, never throws.

42. value_type &value() &

    Wide contract lvalue reference observer of any value present. Constexpr propagating.

43. const value_type &value() const &

    Wide contract const lvalue reference observer of any value present. Constexpr propagating.

44. value_type &&value() &&

    Wide contract rvalue reference observer of any value present. Constexpr propagating.

45. const value_type &&value() const &&

    Wide contract const rvalue reference observer of any value present. Constexpr propagating.

46. error_type &assume_error() & noexcept

    Narrow contract lvalue reference observer of the stored error. Constexpr propagating, never throws.

47. const error_type &assume_error() const & noexcept

    Narrow contract const lvalue reference observer of the stored error. Constexpr propagating, never throws.

48. error_type &&assume_error() && noexcept

    Narrow contract rvalue reference observer of the stored error. Constexpr propagating, never throws.

49. const error_type &&assume_error() const && noexcept

    Narrow contract const rvalue reference observer of the stored error. Constexpr propagating, never throws.

50. error_type &error() &

    Wide contract lvalue reference observer of the stored error. Constexpr propagating.

51. const error_type &error() const &

    Wide contract const lvalue reference observer of the stored error. Constexpr propagating.

52. error_type &&error() &&

    Wide contract rvalue reference observer of the stored error. Constexpr propagating.

53. const error_type &&error() const &&

    Wide contract const rvalue reference observer of the stored error. Constexpr propagating.

54. bool operator==(const basic_result<A, B, C> &) const

    Returns true if this result compares equal to the other result. Constexpr and noexcept propagating.

55. bool operator==(const success_type<A> &) const

    Returns true if this result compares equal to the success type sugar. Constexpr and noexcept propagating.

56. bool operator==(const failure_type<A, void> &) const

    Returns true if this result compares equal to the failure type sugar. Constexpr and noexcept propagating.

57. bool operator!=(const basic_result<A, B, C> &) const

    Returns true if this result does not compare equal to the other result. Constexpr and noexcept propagating.

58. bool operator!=(const success_type<A> &) const

    Returns true if this result does not compare equal to the success type sugar. Constexpr and noexcept propagating.

59. bool operator!=(const failure_type<A, void> &) const

    Returns true if this result does not compare equal to the failure type sugar. Constexpr and noexcept propagating.

60. void swap(basic_result &)

    Swap one basic_result with another, with the strong guarantee. Noexcept propagating.

61. auto as_failure() const &

    Return the output from free function failure() containing a copy of any errored state.

62. auto as_failure() &&

    Return the output from free function failure() containing a move of any errored state.

Exception type publicly inheriting from std::logic_error indicating an incorrect observation of value or error or exception occurred.

Exception type publicly inheriting from bad_result_access indicating an incorrect observation of value occurred, supplying the error value.

Exception type publicly inheriting from std::logic_error indicating an incorrect observation of value or error occurred.

An eagerly evaluated coroutine awaitable with Outcome customisation.

Type sugar for constructing an unsuccessful result or outcome.

A lazily evaluated coroutine generator with Outcome customisation.

Either std::in_place_type_t<T> or a local emulation, depending on the BOOST_OUTCOME_USE_STD_IN_PLACE_TYPE macro.

A lazily evaluated coroutine awaitable with Outcome customisation.

Type sugar for constructing a successful result or outcome.