RUSTSEC-2020-0091: arc-swap: Dangling reference in `access::Map` with Constant

Description

Using the arc_swap::access::Map with the Constant test helper (or with user-provided implementation of the Access trait) could sometimes lead to the map returning dangling references.

Replaced by implementation without unsafe, at the cost of added Clone bound on the closure and small penalty on performance.

More Info

https://github.com/vorner/arc-swap/issues/45

Patched Versions