std.range.chain bug?

[monarch_dodra]

On Monday, 25 November 2013 at 21:04:43 UTC, Jesse Phillips wrote:
> 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.

Really? Why? As a matter of fact, it *works* with string...