Make ConnectionEnd::versions method non-allocating

[seanchen1991]

Crate

ibc-relayer

Summary

The ConnectionEnd::versions getter method clones the versions vector. I think it would make more sense to have this method not allocate and return a &’a [Versions] instead.

Problem Definition

Getter methods in Rust typically return a reference. It’s not explicit in the ConnectionEnd::versions method that it is allocating, so these calls are more expensive than they might seem.

Proposal

It looks like it would be pretty straightforward to change the method to return a slice, as well as convert any downstream calls to the method to accept a &'a [Version] instead. Some call sites will require a .to_vec to get back an owned vector, but I think it makes more sense to do that than to have the versions getter method return an owned vector.

Acceptance Criteria

ConnectionEnd::versions returns a &’a [Versions] and any code calling this method is revised to accept this type as input.

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