[Pre-pre-RFC] "splatting" for named arguments and function overloading

Nadrieril:

You can only splat a generic that implements Tuple, which is only implemented for built-in tuples, so only the crate that defines the trait can define impls for it, unless I'm forgetting some piece of orphan rules magic.

I… somehow overlooked that restriction when writing that section of my post. So yes, the orphan rules for impl ForeiegnTrait for (…) are at least as restrictive as impl ForeiegnTrait<(…)> for ForeiegnType, which is what I suggested as an alternative.