Was this fixed by #128?

The idea with this issue, although not clear in the OP, is to have special methods as an optimization that are variations on this, but possibly also for other constructors:

function FixedSizeArray(a::FixedSizeArray)
    copy(a)
end

That said, now the constructors forward to collect_as, so it would be more general to add such methods to the Collect callable, after #123 is done.

Turns out this doesn't help performance directly, it just helps by allowing effect inference to infer nothrow. Making a PR.