'optional<T&>::and_then(F&& f) &&' calls f with lvalue reference

This makes sense. The 'optional' is an rvalue, but its contained type
remains an lvalue reference. I.e.

int i = 3;
optional<int&>{i}.and_then([](int& r){return optional<int&>{++r});

The optional r-value still refers to 'i', which is not an r-value.
This commit is contained in:
Bj?rn Fahller committed 2018-06-03 12:09:17 +02:00
1 parent f82f78b5b6
commit 5143f9577a
2 files changed
+11 -6

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@@ -1702,11 +1702,11 @@ public:
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template <class F> TL_OPTIONAL_11_CONSTEXPR auto and_then(F &&f) && {
using result = detail::invoke_result_t<F, T &&>;
using result = detail::invoke_result_t<F, T &>;
static_assert(detail::is_optional<result>::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(nullopt);
}
@@ -1725,11 +1725,11 @@ public:
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template <class F> constexpr auto and_then(F &&f) const && {
using result = detail::invoke_result_t<F, const T &&>;
using result = detail::invoke_result_t<F, const T &>;
static_assert(detail::is_optional<result>::value,
"F must return an optional");
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
return has_value() ? detail::invoke(std::forward<F>(f), **this)
: result(nullopt);
}
#endif