Is the documentation description outdated?

[heisen-li]

The description here is：

Composite types such as structs, tuples, and enums are always captured entirely, not by individual fields. It may be necessary to borrow into a local variable in order to capture a single field:

But it should have been done in RFC 2229。

[ehuss]

Yes, the information still needs to be updated. There is some work in #1059, but it is incomplete.
Closing as a duplicate of #1066.