typesafe variadic with default args

[Steven Schveighoffer via Digitalmars-d]

https://issues.dlang.org/show_bug.cgi?id=14651

This doesn't make a whole lot of sense:

void foo(int arg1 = 0, int[] arg2...)
{
}

Error: default argument expected for arg2

The default argument is nothing, like normal, no? I'll note that 
non-typesafe variadic works.

In any case, there is something that *does* work, but it's hideous, and 
doesn't seem to be supported by the grammar:

void foo(int arg1 = 0, int[] arg2 = null...)

Questions:

1. why is original not accepted? This seems like a no-brainer rejects-valid.
2. What is the second one? Is it accepts-invalid, or just not properly 
documented?
3. If 2 is accepts-invalid, will we break code by disabling it? Is it 
worth disabling?

A bizarre consequence of the accepted version is you could have a 
default argument that's larger than a specified argument:

void foo(int[] arg = [1,2,3]...)
{
}

void main()
{
    foo(); // equivalent to foo(1,2,3)
    foo(1); // less args than foo() !
}

-Steve