expected::error() is inconsistently noexcept

[StephanTLavavej]

WG21-N4910 [expected.object.general] class definition:

constexpr const E& error() const &;
constexpr E& error() &;
constexpr const E&& error() const &&;
constexpr E&& error() &&;

[expected.object.obs]/12, /14:

constexpr const E& error() const & noexcept;
constexpr E& error() & noexcept;
constexpr E&& error() && noexcept;
constexpr const E&& error() const && noexcept;

This appears to be an editorial issue - if [expected.object.obs] has decided that they should be noexcept regardless of Preconditions, then the class definition should match.

---

[expected.void.general] class definition:

constexpr const E& error() const &;
constexpr E& error() &;
constexpr const E&& error() const &&;
constexpr E&& error() &&;

[expected.void.obs]/5, /7:

constexpr const E& error() const &;
constexpr E& error() &;
constexpr E&& error() &&;
constexpr const E&& error() const &&;

These consistently omit noexcept, but it makes no sense that the partial specialization would differ from the primary template here. This appears to be worthy of an LWG issue.

I did a quick search and didn't see existing issues covering this.

[frederick-vs-ja]

This has been fixed editorially (cplusplus/draft#5381).

[StephanTLavavej]

Oh, awesome! I'll go patch the <expected> PR to not mark expected<void, E>::error() as having been strengthened.