std.range.chain bug?

[Jesse Phillips]

On Monday, 25 November 2013 at 19:38:44 UTC, Jack Applegame wrote:
> This isn't compiles. Bug?
>
> import std.range;
> class Foo {}
> void main() {
> 	immutable(Foo)[] a;
> 	immutable(Foo)[] b;
> 	auto c = chain(a, b).length;
> }
>
> http://dpaste.dzfl.pl/71272a10

Seems like a bug to me. If Foo where a string I'd expect it to 
fail, but what you have looks reasonable.