env::Args and env::ArgsOs should implement ExactSizedIterator

[nagisa]

And possibly RandomAccessIterator too.

If there is no issues with implementing it, I will gladly fix up a patch for it.

cc @aturon

[nagisa]

By the way, motivation for this is the fact that we have a bunch of os::args().len() inside our codebase and without ExactSizeIterator there’s no good replacement for this.

[alexcrichton]

I'd love to have this! (hurray adding impls backwards compatibly!).

Only catch is to ensure that this is implemented for both windows and unix, otherwise it should be pretty straightforward.