smallvec! macro requires T to be Copy

[samnardoni]

The smallvec! macro, when using the smallvec![a,b,c] form, requires that T: Copy.

This is because the macro expands to use SmallVec::from_slice.

    ($($x:expr),*) => ({
        SmallVec::from_slice(&[$($x),*])
    });

Perhaps it could instead expand into something like...

let s = SmallVec::new();
s.push(a);
s.push(b);
s.push(c);
s

... and remove the need for T: Copy?

[jdm]

That seems like a reasonable change. The macro would probably require something like $(s.push($x);*) if you'd like to make a pull request for this.

[RReverser]

@samnardoni @jdm I made a PR to fix this issue in a relatively performant manner.