Extend the call site default argument expansion mechanism?

[Seb]

On Thursday, 10 May 2018 at 14:15:18 UTC, Yuxuan Shui wrote:
> So in D I can use default argument like this:
>
> int f(int line=__LINE__) {}
>
> [...]

Why not define a TLS or global variable like theAllocator?
Or if you know it at compile-time as an alias?