static if and early exit from function doesn't seem to work?

[aliak via Digitalmars-d-learn]

Alo! I'm making a recursive concat function that is similar to 
chain. The following code works:

import std.range: isInputRange;
auto concat(R, V...)(R range, V values) if (isInputRange!R) {
    import std.range: chain, ElementType;
    static if (V.length) {
        static if (isInputRange!(V[0])) {
            return range.chain(values[0]).concat(values[1..$]);
        } else static if (is(V[0] == ElementType!R)) {
            return range.chain([values[0]]).concat(values[1..$]);
        } // add an else assert here.
    } else {
        return range;
    }
}

But the following does not:

auto concat(R, V...)(R range, V values) if (isInputRange!R) {
    import std.range: chain, ElementType;
    static if (!V.length) {
        return range;
    }
    static if (isInputRange!(V[0])) {
        return range.chain(values[0]).concat(values[1..$]);
    }
    static if (is(V[0] == ElementType!R)) {
        return range.chain([values[0]]).concat(values[1..$]);
    }
}

You get a:

Error: tuple index 0 exceeds 0
Error: template instance range.concat.concat!(Result) error 
instantiating

So it seems it tries to compile the statements below the check on 
V.length even though it's guaranteed to be true and there's a 
return statement inside the if.

Is it a current limitation of static if? or a bug? or is 
something like this just not possible because of something I'm 
not seeing?

Cheers